(en)Embodiments of a hybrid imaging sensor that optimizes a pixel array area on a substrate using a stacking scheme for placement of related circuitry with minimal vertical interconnects between stacked substrates and associated features are disclosed. Embodiments of maximized pixel array size/die size (area optimization) are disclosed, and an optimized imaging sensor providing improved image quality, improved functionality, and improved form factors for specific applications common to the industry of digital imaging are also disclosed.

1.ApplicationNumber: US-201514841340-A
1.PublishNumber: US-2016190197-A1
2.Date Publish: 20160630
3.Inventor: BLANQUART LAURENT

4.Inventor Harmonized: BLANQUART LAURENT(US)

5.Country: US
6.Claims:
(en)Embodiments of a hybrid imaging sensor that optimizes a pixel array area on a substrate using a stacking scheme for placement of related circuitry with minimal vertical interconnects between stacked substrates and associated features are disclosed. Embodiments of maximized pixel array size/die size (area optimization) are disclosed, and an optimized imaging sensor providing improved image quality, improved functionality, and improved form factors for specific applications common to the industry of digital imaging are also disclosed.

7.Description:
(en)CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation of co-pending U.S. patent application Ser. No. 13/471,267, filed May 14, 2012, entitled “PIXEL ARRAY AREA OPTIMIZATION USING STACKING SCHEME FOR HYBRID IMAGE SENSOR WITH MINIMAL VERTICAL INTERCONNECTS,” now U.S. Pat. No. 9,123,602, which claims the benefit of: (1) U.S. Provisional Application No. 61/485,426, filed May 12, 2011; (2) U.S. Provisional Application No. 61/485,432, filed May 12, 2011; (3) U.S. Provisional Application No. 61/485,435, filed May 12, 2011; and, (4) U.S. Provisional Application No. 61/485,440, filed May 12, 2011, which are all hereby incorporated by reference herein in their entireties, including but not limited to those portions that specifically appear hereinafter, the incorporation by reference being made with the following exception: In the event that any portion of the above-referenced applications are inconsistent with this application, this application supersedes said above-referenced applications.


STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable.
BACKGROUND
The disclosure relates generally to electromagnetic sensing and sensors and also relates to low energy electromagnetic input conditions as well as low energy electromagnetic throughput conditions. The disclosure relates more particularly, but not necessarily entirely, to optimizing the pixel array area and using a stacking scheme for a hybrid image sensor with minimal vertical interconnects between substrates and associated systems, methods and features, which may also include maximizing pixel array size/die size (area optimization).
There has been a popularization of the number of electronic devices that utilize and include the use of imaging/camera technology in general. For example, smartphones, tablet computers, and other handheld computing devices all include and utilize imaging/camera technology. The use of imaging/camera technology is not limited to the consumer electronics industry. Various other fields of use also utilize imaging/camera technology, including various industrial applications, medical applications, home and business security/surveillance applications, and many more. In fact, imaging/camera technology is utilized in nearly all industries.
Due to such popularization, the demand for smaller and smaller high definition imaging sensors has increased dramatically in the marketplace. The device, system and methods of the disclosure may be utilized in any imaging application where size and form factor are considerations. Several different types of imaging sensors may be utilized by the disclosure, such as a charged-couple device (CCD), or a complementary metal-oxide semiconductor (CMOS), or any other image sensor currently known or that may become known in the future.
CMOS image sensors typically mount the entire pixel array and related circuitry, such as analog-digital converters and/or amplifiers, on a single chip. Because of the physical constraints of the chip size itself and the physical space occupied by related circuitry involved in a conventional CMOS image sensor, the area that the pixel array may occupy on the chip is often limited. Thus, even if the pixel array were maximized on a substrate that also contains the related circuitry, the pixel array is physically limited in area due to the amount of physical area and space that the related circuitry for signal processing and other functions occupies on the chip.
Further, the application or field of use in which the CMOS image sensor may be used often requires the CMOS image sensor to be limited to a certain size also limiting the physical area in which the pixel array may occupy. The size limitations of a CMOS image sensor often require trade-offs between image quality and other important functions, such as signal processing, due to the number of considerations that must be accounted for in the design and manufacture of a CMOS image sensor. Thus, for example, increasing the pixel array area may come with a trade-off in other areas, such as A/D conversion or other signal processing functions, because of the decreased area in which the related circuitry may occupy.
The disclosure optimizes and maximizes the pixel array without sacrificing quality of the signal processing by optimizing and maximizing the pixel array on a first substrate and stacking related circuitry on subsequent substrates. The disclosure utilizes advancements in back-side illumination and other areas to take advantage of optimizing the area of the pixel array on a substrate. The stacking scheme and structure allow highly functional, large-scale circuits to be utilized while maintaining a small chip size.
The features and advantages of the disclosure will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by the practice of the disclosure without undue experimentation. The features and advantages of the disclosure may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims.



BRIEF DESCRIPTION OF THE DRAWINGS
The features and advantages of the disclosure will become apparent from a consideration of the subsequent detailed description presented in connection with the accompanying drawings in which:
FIG. 1 a is a schematic view of an embodiment of an imaging sensor constructed on a single substrate;
FIG. 1 b is a schematic view of an embodiment of an imaging sensor, demonstrating the remote placement of processing circuits relative to a pixel array in accordance with the teachings and principles of the disclosure;
FIG. 2 illustrates a schematic view of an embodiment of an imaging sensor built on a plurality of substrates in accordance with the teachings and principles of the disclosure;
FIG. 3 a illustrates a perspective view of an embodiment of an imaging sensor made on a monolithic and illustrating a plurality of columns comprising pixels and supporting circuitry, where the supporting circuitry is one pixel in width;
FIG. 3 b illustrates a top view of an embodiment of an imaging sensor made on a monolithic and illustrating a plurality of columns comprising pixels and supporting circuitry, where the supporting circuitry is one pixel in width;
FIG. 3 c illustrates a perspective view of a single column comprising pixels and supporting circuitry taken from FIG. 3 a;
FIG. 3 d illustrates a top view of a single column comprising pixels and supporting circuitry taken from FIG. 3 b;
FIG. 3 e illustrates a perspective view of an embodiment of an imaging sensor made on a monolithic and illustrating a plurality of columns comprising pixels and supporting circuitry, where the supporting circuitry is two pixels in width;
FIG. 3 f illustrates a top view of an embodiment of an imaging sensor made on a monolithic and illustrating a plurality of columns comprising pixels and supporting circuitry, where the supporting circuitry is two pixels in width;
FIG. 3 g illustrates a perspective view of an embodiment of an imaging sensor built on a plurality of substrates with a pixel array on the first substrate and supporting circuitry located on a second or subsequent substrate with interconnects and vias being shown connecting the plurality of substrates in accordance with the teachings and principles of the disclosure;
FIG. 3 h illustrates a front view of the embodiment of an imaging sensor built on a plurality of substrates of FIG. 3 g;
FIG. 3 i illustrates a perspective view of an embodiment of an imaging sensor built on a plurality of substrates wherein a plurality of pixel columns forming the pixel array are located on the first substrate and a plurality of circuit columns are located on a second substrate and showing an electrical connection and communication between one column of pixels to its associated or corresponding column of circuitry;
FIG. 3 j illustrates a perspective view of a single column of pixels and a single column of circuitry taken from FIG. 3 i showing an electrical connection therebetween;
FIG. 3 k illustrates a front view of the single column of pixels and the single column of circuitry taken from FIGS. 3 i and 3 j showing an electrical connection therebetween;
FIG. 3 l illustrates a side view of the single column of pixels and the single column of circuitry taken from FIGS. 3 i and 3 j showing an electrical connection therebetween;
FIG. 3 m illustrates a perspective view of an embodiment of an imaging sensor built on a plurality of substrates wherein a plurality of pixel columns forming the pixel array are located on the first substrate and a plurality of circuit columns are located on a second substrate and showing a plurality of electrical connections and communication between the plurality of pixel columns and associated or corresponding columns of circuitry;
FIG. 3 n illustrates a perspective view of an embodiment of an imaging sensor built on a plurality of substrates wherein a plurality of pixel columns forming the pixel array are located on the first substrate and a plurality of circuit columns are located on a second substrate, wherein the circuit columns are two pixels in width and half of the length of the pixel column, and showing a plurality of electrical connections and communication between the plurality of pixel columns and associated or corresponding columns of circuitry;
FIG. 3 o illustrates a perspective view of a single column of pixels and a single column of circuitry taken from the right most column of FIG. 3 n showing an electrical connection therebetween;
FIG. 3 p illustrates a front view of the single column of pixels and the single column of circuitry taken from FIGS. 3 n and 3 o showing an electrical connection therebetween;
FIG. 3 q illustrates a side view of the single column of pixels and the single column of circuitry taken from FIGS. 3 n and 3 o showing an electrical connection therebetween;
FIG. 3 r illustrates a perspective view of a single column of pixels and a single column of circuitry taken from the left most column of FIG. 3 n showing an electrical connection therebetween;
FIG. 3 s illustrates a front view of the single column of pixels and the single column of circuitry taken from FIGS. 3 n and 3 r showing an electrical connection therebetween;
FIG. 3 t illustrates a side view of the single column of pixels and the single column of circuitry taken from FIGS. 3 n and 3 r showing an electrical connection therebetween;
FIG. 3 u illustrates a perspective view of an embodiment of an imaging sensor built on a plurality of substrates wherein a plurality of pixel columns forming the pixel array are located on the first substrate and a plurality of circuit columns are located on a second substrate, wherein the circuit columns are four pixels in width, and showing a plurality of electrical connections and communication between the plurality of pixel columns and associated or corresponding columns of circuitry;
FIG. 3 v illustrates a perspective view of a single column of pixels and a single column of circuitry taken from the right most column of FIG. 3 u showing an electrical connection therebetween;
FIG. 3 w illustrates a front view of the single column of pixels and the single column of circuitry taken from FIGS. 3 u and 3 v showing an electrical connection therebetween;
FIG. 3 x illustrates a side view of the single column of pixels and the single column of circuitry taken from FIGS. 3 u and 3 v showing an electrical connection therebetween;
FIG. 3 y illustrates a perspective view of a single column of pixels and a single column of circuitry taken from the column to the left of adjacent to the right most column of FIG. 3 u showing an electrical connection therebetween;
FIG. 3 z illustrates a front view of the single column of pixels and the single column of circuitry taken from FIGS. 3 u and 3 y showing an electrical connection therebetween;
FIG. 3 aa illustrates a side view of the single column of pixels and the single column of circuitry taken from FIGS. 3 u and 3 y showing an electrical connection therebetween;
FIG. 4 illustrates an embodiment of an imaging sensor built on a plurality of substrates and also illustrating an embodiment of the specific placement of support circuits in accordance with the teachings and principles of the disclosure;
FIG. 5 illustrates an embodiment of an imaging sensor built on a plurality of substrates and also illustrating an embodiment of the specific placement of support circuits wherein some of the circuits are relatively remotely placed in accordance with the teachings and principles of the disclosure;
FIG. 6 illustrates an embodiment of a first substrate having various percentages of coverage by differing pixel arrays in accordance with the teachings and principles of the disclosure;
FIG. 7 illustrates an embodiment having a plurality of pixel arrays in accordance with the teachings and principles of the disclosure;
FIG. 8 illustrates an embodiment of an image sensor with an optimized pixel array and related or supporting circuitry being stacked and illustrating a light source in accordance with the teachings and principles of the disclosure;
FIG. 9 illustrates a backside illuminated embodiment of an image sensor with an optimized pixel array and related or supporting circuitry being stacked in accordance with the teachings and principles of the disclosure;
FIG. 10 illustrates an embodiment of an image sensor wherein the pixel array is more remotely located from all said supporting circuits in accordance with the teachings and principles of the disclosure;
FIG. 11 illustrates an embodiment of an image sensor having stacked substrates of differing size in accordance with the teachings and principles of the disclosure;
FIG. 12 illustrates an embodiment of pixel architecture, where each pixel column does not share a read bus with another pixel column; and
FIG. 13 illustrates an embodiment of pixel architecture, where there is a horizontal 2-way share of pixel columns with respect to a read bus, such that there is one read bus per two pixel columns.



DETAILED DESCRIPTION
For the purposes of promoting an understanding of the principles in accordance with the disclosure, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended. Any alterations and further modifications of the inventive features illustrated herein, and any additional applications of the principles of the disclosure as illustrated herein, which would normally occur to one skilled in the relevant art and having possession of this disclosure, are to be considered within the scope of the disclosure claimed.
Before the structure, systems and methods for optimizing pixel array area using a stacking scheme for a hybrid image sensor with minimal vertical interconnects between substrates are disclosed and described, it is to be understood that this disclosure is not limited to the particular structures, configurations, process steps, and materials disclosed herein as such structures, configurations, process steps, and materials may vary somewhat. It is also to be understood that the terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting since the scope of the disclosure will be limited only by the appended claims and equivalents thereof.
It must be noted that, as used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.
In describing and claiming the subject matter of the disclosure, the following terminology will be used in accordance with the definitions set out below.
As used herein, the terms “comprising,” “including,” “containing,” “characterized by,” and grammatical equivalents thereof are inclusive or open-ended terms that do not exclude additional, unrecited elements or method steps.
As used herein, the phrase “consisting of” and grammatical equivalents thereof exclude any element or step not specified in the claim.
As used herein, the phrase “consisting essentially of” and grammatical equivalents thereof limit the scope of a claim to the specified materials or steps and those that do not materially affect the basic and novel characteristic or characteristics of the claimed disclosure.
As used herein, the term “proximal” shall refer broadly to the concept of a portion nearest an origin.
As used herein, the term “distal” shall generally refer to the opposite of proximal, and thus to the concept of a portion farther from an origin, or a furthest portion, depending upon the context.
Digital imaging, whether still or movie, has many constraints placed upon it with regard to the devices used to record the image data. As discussed herein, an imaging sensor may include a pixel array and supporting circuits that are disposed on at least one substrate. Devices usually have practical and optimal constraints on the form factor of the imaging sensor depending upon the application. With most applications, especially for commercial use, size is usually a constraint. Even in outer space applications where size would seemingly be the least constrained, size is still an issue because the imaging device needs to be orbitally launched and overcome the force of gravity. Additionally, and especially in consumer electronics, any bulk added by the imaging device/camera takes away from possible other functional hardware or battery capacity/life. Thus, size is nearly always a constraint that must be addressed in any application using an imaging sensor.
In many cases, the form factor of an imaging device is constrained. There may be unlimited area or real estate laterally, relative to the pixel array, or there may be an abundance of space directly behind a pixel array. Often it is not the pixel array that is the only consideration for fitment, but it is the supporting circuitry that needs to be accommodated. The supporting circuits may be, but are not necessarily limited to, analog to digital converters, power circuits, power harvesters, amplifier circuits, dedicated signal processors and filters, serializers for data transmission, etc. In addition to circuits, physical property elements may be required, such as light filters and lenses. All of the above must be considered when deciding on and designing the form factor of an imaging device and traditionally the industry has chosen lateral placement of supporting circuits when designing the image sensors of the day. Yet, there are many applications that would benefit from a more vertical rather than lateral form factor.
An example of an application that would benefit from an imaging device having a relatively vertical (relative to the pixel array) form factor would be in the fields of use requiring the use of a scope. For example, industrial scopes and medical endoscopes would benefit from an image sensor that could be housed within a lumen of the device. In such a scope application, an image sensor that could be disposed in the lumen of the scope may be advantageous. The inside diameter (if round) of the lumen would then define maximum diameter (round) of the image sensor. With a popular lumen size range of 3 mm to 15 mm, it will be appreciated that the image sensor will be greatly limited in form factor considerations in the lateral direction due to the inside diameter constraints. Accordingly, a more vertical configuration may be advantageous.
Although size is an issue as stated above, pixel count numbers continue to climb industry wide, and often eclipse the mediums that are used to actually view the images after they have been recorded, such as a computer monitor or television. However, it should be understood that all pixels are not created equal. In the example above, a scope configuration may be used in a limited light application. As such, a scope based image sensor that functions well in low light situations may be advantageous. Large pixels have the ability to collect more light than small pixels simply because of their different sizes. However, the trend in the marketplace has been to increase the number of pixels in a given form factor. Logically, more pixels in a given area generally mean smaller pixel size. Smaller pixels have the shortfalls of not working well in lower light and creating noise because of the electronic crowding. Additionally, more pixels equates to more boundary space relative to light gathering space. Larger pixels tend to produce better images and higher image quality because they simply have a larger ratio of light sensing portion to border portion. Both of those issues lend to the poor image quality of today small image sensors.
The issues stated above describe the current state of the art relative to a few needs within the industry. What is needed is an image sensor having adequate resolution by way of pixel count, a vertical architecture and form factor, and as large as possible pixel size, all while constrained in a limited space. The disclosure below will discuss embodiments and methods of design that address these issues by optimizing the size of the pixel array and remotely locating supporting circuits in a generally vertical configuration.
The disclosure contemplates an image sensor that might otherwise be manufactured with its pixel array and supporting circuitry on a single, monolithic substrate/chip and separating the pixel array from all or a majority of the supporting circuitry. The disclosure may use at least two substrates/chips, which will be stacked together using three-dimensional stacking technology. The first of the two substrates/chips may be processed using an image CMOS process. The first substrate/chip may be comprised either of a pixel array exclusively or a pixel array surrounded by limited circuitry when compared to typical monolithically designed image sensors. The second substrate/chip may be, but is not limited to, a highly dense digital process in order to integrate a variety and number of functions in a very limited space or area on the substrate/chip, or a mixed-mode or analog process in order to integrate for example precise analog functions, or a RF process in order to implement wireless capability, or MEMS (Micro-Electro-Mechanical Systems) in order to integrate MEMS devices. The image CMOS substrate/chip may be stacked with the second or subsequent substrate/chip using any three-dimensional design technique. The second substrate/chip may support most, or a majority, of the circuitry that would have otherwise been implemented in the first image CMOS chip (if implemented on a monolithic substrate/chip) as peripheral circuits and therefore have increased the overall system area while keeping the pixel array size constant and optimized to the fullest extent possible on the first substrate. The electrical connection between the two substrates/chips may be accomplished through interconnects, which may be wirebonds, ubumps and/or TSVs (Through Silicon Via).
Referring now to FIGS. 1 a and 1 b , FIG. 1 a an example of an imaging sensor of monolithic design wherein a single substrate is used as the basis of chip construction. As can be seen in FIG. 1 a , a substrate 102 a may comprise a pixel array 150 a that is configured to receive electromagnetic energy, convert it to data, and then pass that data on to supporting circuits 110 a , 120 a , 130 a for processing that will ultimately result in a digital image or video. The supporting circuits may include signal processing circuits such analog to digital converters 110 a , amplifier circuits 130 a , filter circuits, power supplying and harvesting circuits 120 a , and serial processors to name only a few. Some of the supporting circuits may be located nearer to the pixel array than other circuits and connected to each pixel of the pixel array via buses. For example, amplification circuits and digital conversion circuits may be preferred to be located closer to the pixel array because that architecture may increase the clarity of the data stream and introduce minimal noise to the system. As can be seen in FIG. 1 a , image sensor 100 a is a schematic illustration of what is typically available in the marketplace with regard to image sensors. FIG. 1 a illustrates a generally lateral placement of the supporting circuits relative to the pixel array 150 a , which dominates the marketplace today because of cost and manufacture limitations. Lateral placement of the supporting circuits on the same substrate as, and with respect to, the pixel array 150 a simplifies the architecture and reduces the cost of production. However, the use of a single substrate has some drawbacks and limitations, such as form factor issues, because not all applications lend themselves to a lateral or horizontal circuit placement as discussed above.
As is illustrated in FIG. 1 b , when the support circuits, such as 110 a , 120 a , 130 a , are removed from the first substrate 160 there remains considerable room for a larger pixel array 150 a to be located on the first substrate 160 , which means more or larger pixels can be used. Given the same physical limitations in an electronic device using an imaging sensor, using the techniques and combination of features disclosed herein allows either increased pixel resolution or increased pixel size to be used. In such cases, the image sensor substrates can be reduced in size and used in more devices where size is of primary concern and yet a high quality image is desired. Specifically, the FIG. ( 1 b ) illustrates the design concept of remotely locating support circuits 110 b , 120 b and 130 b relative to the pixel array.
Referring primarily to FIG. 2 , the use of supporting substrates to carry supporting circuits will be discussed. In an embodiment of an exemplary image sensor 200 , a pixel array 205 , which may comprise a plurality of pixels that are formed into a plurality of pixel columns, are positioned on a surface of a first substrate 210 . Each of the plurality of pixel columns located on the first substrate 210 may be electrically connected to a read bus 240 . Signal processing and image enhancement may be performed by supporting circuits located on a second substrate 220 . The circuits may include signal processing circuits, such as analog to digital converters 228 , amplifier circuits 226 , filter circuits 224 , power supplying and harvesting circuits 222 , which may be formed into a plurality of circuit columns that correspond with the plurality of pixel columns on the first substrate 210 . Each circuit column may be comprised of a plurality of supporting circuits that is in electronic communication with a read bus 230 or plurality of read buses corresponding to each circuit column. In other words, the signal processing circuits may be located on a second substrate or supporting substrate 220 . Each of the plurality of circuit columns on the second substrate 220 may then be electronically connected to a corresponding pixel column located on the first substrate 210 through an interconnect, such as a solder bump, solder ball or via, which may be located anywhere along the physical path where the read buses 230 , 240 are superimposed or overlap. It is also within the scope of this disclosure to contemplate the use of a plurality of secondary substrates, each substrate housing any needed circuits for an image sensor and in any order or combination of supporting circuits depending upon the desired function of the image sensor.
As illustrated in FIGS. 3 a through 3 f , an image sensor 300 a may generally comprise a pixel array 350 a and supporting circuitry 370 a , which may comprise an analog to digital converter 317 a , an amplifier 315 a , a filter 314 a and a clock 316 a all of which may be disposed on a monolithic substrate 310 a . In FIGS. 3 a and 3 b , a monolithic image sensor is illustrated in a perspective view and a top view, respectively. The pixel array 350 a may be comprised of a plurality of pixel columns, wherein each of the plurality of pixel columns 352 a comprises a plurality of individual pixels. The supporting circuitry 370 a may comprise a plurality of circuit columns 356 a , wherein each of the circuit columns 356 a comprises circuitry to support a corresponding pixel column 352 a . As illustrated in the figures, the monolithic circuit columns 356 a are each one pixel in width and are locally located relative to a pixel column to which they correspond. The figures illustrate a pixel array of unshared pixels with one read bus per pixel column electrically connected to the corresponding column circuitry on one side of the image sensor only. It will be appreciated that the corresponding circuitry is one pixel wide in the embodiment, however, other configurations of support circuitry as discussed below are contemplated within the scope of this disclosure and may be used to increase the image sensor design options.
Referring now to FIGS. 3 c and 3 d , a single pixel column 352 a comprising a plurality of pixels and a single circuit column 356 a are illustrated in a perspective view and a top view, respectively. It will be appreciated that the single pixel column 352 a and the corresponding circuit column 356 a illustrated in the figures are taken from the image sensor 300 a illustrated in FIGS. 3 a and 3 b and simply denote a single pixel column 352 a electrically connected to a single circuit column 356 a.
FIGS. 3 e and 3 f illustrate a perspective view and a top view of an embodiment of an imaging sensor 300 a made on a monolithic substrate and illustrating a plurality of columns comprising pixels and supporting circuitry. In contrast to FIGS. 3 a and 3 b , FIGS. 3 e and 3 f illustrate the supporting circuitry as being two pixels in width. In the figures it can be seen that alternating pixel columns 352 a read to corresponding circuitry located at opposing ends of the pixel columns 352 a . Such a configuration offers variations in aspect ratios of corresponding circuit column 356 a areas. Because the buses 330 a read to alternating ends of the pixel array 350 a , the circuit column 356 a can be two pixels wide. Contrasting the sensors illustrated in FIGS. 3 b and 3 f , the pixel column 352 a illustrated in FIG. 3 b has an aspect ratio of six pixels (units) long by one pixel wide (6/1) and the circuit column 356 a has a similar aspect ratio. Conversely, the image sensor illustrated in FIG. 3 f has a pixel column 352 a that has an aspect ratio of six pixels (units) long by one pixel wide (6/1) and the circuit column 356 a has an aspect ratio of two pixels wide and three pixels long (2/3). In contrast, the same functionality of an imaging sensor 300 a built on a monolithic substrate (shown in FIGS. 3 a -3 f ) can be provided and supplied in an imaging sensor 300 that has a much smaller dimension (in at least the lateral direction and having a much smaller area and form factor) than a monolithic substrate or chip. Referring now to FIGS. 3 g through 3 aa , an imaging sensor 300 will be discussed that may comprise a pixel array 350 that may be disposed on a first substrate 310 , while all of the supporting circuits 370 may be remotely located (with respect to the pixel array 350 and first substrate 310 ) to one or more supporting substrates, such as a second substrate 311 and a third substrate 312 .
It should be noted that the image sensor may be built and manufactured on a plurality of substrates. Each of the plurality of substrates may be located with respect to each other in a stacked configuration or formation, where all of the supporting substrates are stacked or aligned behind the first substrate 310 , which comprises the pixel array 350 , and relative to an object to be imaged. Each of the substrates in the stack may be electrically connected through interconnects 321 , such as solder bumps or solder balls, vias or other forms of electrical communication. It will be appreciated that the interconnects 321 may include any known means or method for conducting electrical signals to various circuits on the same or different substrates without departing from the scope of the disclosure.
In FIGS. 3 g , 3 i , 3 m , 3 n , and 3 u , each of the plurality of substrates comprising the pixel array 350 and the various supporting circuits 370 of the image sensor 300 may be of similar size in the stack, such that the plurality of substrates may be substantially aligned within the stack. In an embodiment, the first substrate 310 and the plurality of subsequent supporting substrates 311 may be stacked in substantial alignment so that a plurality of communication columns are formed in a multi-layer stack of substantially the same length and width.
It should be noted that in other embodiments, where the form factor will allow it, different sized substrates having different lengths and widths may be used and may be preferred in the stack. Considerations such as heat dissipation and noise, along with many more considerations, may be accounted for when designing a stacked configuration. For example, in an embodiment, a high heat circuit, such as an amplifying circuit, may be placed on a protruding portion of one of the supporting substrates within a stack (illustrated best in FIG. 11 ).
It should be noted that a pixel array 350 may be formed in a plurality of rows of pixels and a plurality of columns of pixels. Each pixel column 352 may comprise a plurality of pixels in a linear form factor, which is one pixel wide and “N” pixels long. It should be further noted that each pixel column 352 will have an area value that is generally as wide as the pixel pitch and as long as is predetermined by sensor design.
Conversely, a circuit column 356 , as referred to herein, is an allocated space on a substrate, other than a first substrate 310 comprising the pixel array 350 , which comprises at least one support circuit 370 that is dedicated and electrically connected to, or in electrical communication with, a corresponding pixel column 352 . It will be appreciated that the space occupied by the pixel column 352 may be the same as, or substantially the same as, the space occupied by the circuit column 356 that corresponds with that pixel column 352 . Thus, the second or supporting substrate 311 may comprise a plurality of circuit columns 356 , wherein each circuit column 356 comprises substantially the same or similar real estate area on the second substrate 311 as a corresponding pixel column 352 has area on the first substrate 310 .
Additionally, each pixel column 352 is or may be in electronic communication with a read bus 330 on the first substrate 310 , while the circuit column 356 is or may be in electronic communication with a read bus 340 on the second substrate 311 . The two aforementioned buses 330 , 340 may be electrically connected by at least one interconnect 321 that is located anywhere along the path created by, or within, the superimposition of or between the two buses 330 , 340 as illustrated in FIGS. 3 g through 3 aa . In an embodiment, a plurality of interconnects 321 may be used to connect a single pixel column 352 to a single corresponding circuit column 356 . In such an embodiment, the redundancy in the number of interconnects 321 used may provide for increased production yield or increased functionality.
As referred to herein, aspect ratio will be used to refer to the general shape of an area on a substrate. For example, an area defined as being 4 pixel units wide and 5 pixel units long will have an aspect ratio of 4/5 or 5/4. The term aspect ratio may be used generically to denote a situation where the shape of an area is considered important. For example, the concept of aspect ratio may be used to denote differences in the aspect ratios of two corresponding areas that are located on differing substrates. It should be noted that the aspect ratios of the pixel columns 352 and the circuit columns 356 illustrated in FIGS. 3 g - 3 aa may be the same or may be different, the area of the footprint of the pixel column 352 and its corresponding circuit column 356 may be substantially the same or equal. Several examples of different aspect ratios are illustrated in FIGS. 3 g through 3 aa , but it should be noted that the principles of this disclosure may be applied to any number of aspect ratio configurations. However, as illustrated in the figures, the area of the circuit column 356 footprint or real estate is substantially the same as or equal to the area of the footprint or real estate of the pixel column 352 . As manufacturing techniques improve or design parameters change more or less area may be needed for the supporting circuits 370 of the circuit column 356 .
Referring specifically to FIGS. 3 g and 3 h , the supporting circuitry 370 , which may include an amplifier, a filter, a clock or other circuitry needed to support an image sensor, may all be disposed on one or more supporting substrates, such as a second substrate 311 . However, it will be appreciated that such circuits may be dispersed on one or more substrates, such as the second substrate 311 , or a third substrate. Additionally, an analog to digital converter may be remotely located on one of the supporting substrates. It will be appreciated that the order and location of the supporting circuits 370 may be changed and may be located on any of the supporting substrates as desired.
As can be seen in the figures, each pixel column 352 may be associated and electrically connected to one read bus 330 on the first substrate 310 , while each of the circuit columns 356 may be associated and electrically connected to one read bus 340 on the supporting substrate 311 by one or more interconnects 321 , which may include both ubumps 321 a and vias 321 b (illustrated best in FIG. 3 h ). At least one interconnect 321 may be used to connect a pixel column bus 330 on the first substrate 310 to a circuit column bus 340 on the supporting substrate 311 as illustrated. The dashed arrows in FIGS. 3 i , 3 j , 31 , 3 o , 3 q , 3 r , 3 t , 3 v , 3 x , 3 y and 3 aa illustrate that the interconnects 321 may be located anywhere along the superimposition path of the two read buses 330 and 340 per corresponding pixel column 352 and circuit column 356 .
Referring now to FIGS. 3 i through 3 m , there is illustrated various views of an embodiment of an imaging sensor 300 built on a plurality of substrates. FIGS. 3 i and 3 m illustrate a plurality of pixel columns 352 forming the pixel array 350 on the first substrate 310 and a plurality of circuit columns 356 (that represent the supporting circuitry 370 ) on the second substrate 311 . As illustrated, the circuit columns 356 may be one pixel in width and “N” number of pixels long to correspond directly with the pixel column 352 to which the circuit column 356 is associated. The figures show an example of a connection between each pixel column 352 to its associated circuitry 370 in a circuit column 356 . The figures also show one read bus 330 per pixel column 352 and one read bus 340 per circuit column 356 , where the associated circuitry 370 in a circuit column 356 is one pixel column wide.
As noted herein above, each pixel column 352 may be electrically associated or connected to one pixel column bus 330 , and each circuit column 356 may be electrically associated or connected to one circuit column bus 340 . FIGS. 3 j through 3 l illustrate a perspective view, a front view and a side view, respectively, of a single pixel column 352 and a single circuit column 356 separated from the plurality of pixel columns 352 and plurality of circuit columns 356 illustrated in FIG. 3 i . FIGS. 3 j through 3 l further illustrate the electrical connection between the buses 330 and 340 of the pixel column 352 and the circuit column 356 using one or more interconnects 321 . While the buses 330 and 340 may be electrically connected using one or more interconnects 321 , the figures illustrate that the interconnect 321 may be located anywhere along the superimposed path of the buses 330 and 340 without departing from the spirit or scope of the disclosure.
Referring now to FIG. 3 n through 3 t , there is illustrated various views of an embodiment of an imaging sensor 300 built on a plurality of substrates, wherein a plurality of pixel columns 352 forming the pixel array 350 are located on the first substrate 310 and a plurality of circuit columns 356 are located on a second substrate 311 . In this embodiment, the circuit columns 356 may be two pixels or two pixel columns in width. In this example, the connection between each pixel column 352 to its associated circuitry 370 in a corresponding circuit column 356 may be one read bus 330 , 340 per pixel column 352 and circuit column 356 . As can be seen in the figure, the area consumed by the pixel column 352 on the first substrate 310 corresponds to an area consumed by a corresponding circuit column 356 . Such correspondence allows for direct overlay of the substrates, for example 310 and 311 , such that support circuits 370 in a circuit column 356 are directly stacked with the pixel column 352 they support.
It should also be noted that in such a configuration, the aspect ratio of the pixel column 352 will be substantially equal to the aspect ratio of the circuit column 356 , however such aspect ratio equality is not required as discussed further below. As can be seen in FIG. 3 m the pixel column is one pixel column wide and six pixels long, so the aspect ratio is 1/6. The circuit column also has the same aspect ratio of 1/6. In contrast, FIG. 3 n illustrates a design wherein the circuit column aspect ratio is twice as wide as the pixel column aspect ratio, but is only half as long, thereby providing a possibly more usable footprint in which to place supporting circuits. In both FIGS. 3 m and 3 n , the area of the footprint of both the pixel column 352 and the circuit column 356 is substantially equal to each other even though the aspect ratios are different.
FIG. 3 n also illustrates how differing aspect ratios between the substrates can allow for flexibility in bus contact points. In the embodiment, the column circuit bus 340 has been designed with a general “u” shape that so as to occupy the area of the circuit column 356 more evenly, thereby providing options for connecting the interconnect 321 throughout the entire circuit column 356 . Note that the pixel column bus 330 is not generally u-shaped, but the circuit column bus 340 may be generally u-shaped, so that the same column circuit 356 may be used with the two different pixel column configurations of FIGS. 3 o and 3 r . The first leg of the u-shaped circuit column bus 340 may be superimposed to the read bus 330 of the first pixel column 352 (as illustrated in FIG. 3 o ) and the second leg of the u-shaped circuit column bus 340 may be superimposed to the read bus 330 of the next, adjacent pixel column 352 (as illustrated in FIG. 3 r ). FIG. 3 o and FIG. 3 r illustrate pixel columns 352 taken from the pixel array 350 of FIG. 3 n . FIG. 3 o and FIG. 3 r illustrate three options for interconnect 321 positioning within the circuit column 356 footprint. In should be noted, as illustrated in FIG. 3 q , that because the aspect ratio of the circuit column 356 is illustrated as being twice as wide, but one half the length of the corresponding pixel column 352 , the interconnect 321 location options are only available for a portion of the pixel column 352 length. FIG. 3 p illustrates that for a complex bus shape there may be two interconnect location path options along a bus 340 in a circuit column 356 having twice the width of the pixel column 352 it supports. FIG. 3 p illustrates a front view of the superimposition of the first leg of the u-shaped circuit column bus 340 to the read bus 330 of the first pixel column 352 and uses the outer most portion of the bus 340 for locating the interconnect 321 as opposed to the innermost portion of the bus 340 as illustrated in FIGS. 3 r and 3 s for locating the interconnect 321 to the next, adjacent pixel column 352 . FIG. 3 r illustrates the next pixel column 352 located to the left of and relative to the first pixel column illustrated in FIGS. 3 n (right most pixel column) and 3 o . The bus 330 of the second pixel column 352 illustrated in FIG. 3 r may be electrically connected to the second leg of the bus 340 as illustrated. It should be noted that because the footprint of the circuit column 356 has an aspect ratio of 2/3, the superimposition of the pixel column bus 330 to the circuit column bus 340 requires the second leg of the circuit column bus 340 to be generally u-shaped to thereby allow a natural match or superimposition of the buses 330 and 340 with respect to the next pixel column 352 illustrated in FIGS. 3 r and 3 s.
FIG. 3 u illustrates a perspective view of an embodiment of an imaging sensor 300 built on a plurality of substrates wherein a plurality of pixel columns 352 forming the pixel array 350 are located on the first substrate 310 and a plurality of circuit columns 356 are located on a second substrate 311 , wherein the circuit columns 356 are four pixels in width, but are also one fourth the length. The figure also illustrates a plurality of electrical connections and communication paths between the plurality of pixel columns 352 and associated or corresponding columns 356 of circuitry.
FIG. 3 v illustrates a perspective view of a single column of pixels 352 and a single column of circuitry 356 taken from the right most column of FIG. 3 u showing an electrical connection therebetween and an illustrative bus configuration to accommodate the architecture. As can be seen in the figure, an embodiment may comprise a pixel column 352 (and associated bus 330 ) that has a minimal portion of overlay with a corresponding circuit column 356 (and associated bus 340 ). In other words, very little bus superimposition is required between substrates. However, as illustrated in FIG. 3 u , there may be superimposition on the substrate level.
FIG. 3 w illustrates a front view of the single column of pixels 352 and the single column of circuitry 356 taken from FIG. 3 v showing an electrical connection therebetween. As can be seen in the figure, only a small lateral portion of bus superimposition is needed to connect the pixel column 352 to the circuit column 356 .
FIG. 3 x illustrates a side view of the single column of pixels 352 and the single column of circuitry 356 taken from FIG. 3 v showing an electrical connection therebetween. As can be seen in the figure, one or more interconnects 321 can be used in some embodiments and the figure also illustrates that the placement of the interconnects 321 may be anywhere along the superimposition of the buses 330 and 340 .
FIG. 3 y illustrates a perspective view of a single column of pixels 352 and a single column of circuitry 356 taken from the column to the left of, and adjacent to, the right most column 356 of FIG. 3 u showing an electrical connection therebetween. FIG. 3 z illustrates a front view of the single column of pixels 352 and the single column of circuitry 356 taken from FIG. 3 y showing an electrical connection therebetween. FIG. 3 v and FIG. 3 y illustrate pixel columns 352 taken from the pixel array 350 of FIG. 3 u . FIG. 3 v and FIG. 3 y illustrate two options for interconnect 321 positioning within the circuit column 356 footprint. It should be noted, as illustrated in FIG. 3 aa , that because the aspect ratio of the circuit column is wider, but shorter than that of the corresponding pixel column 352 , the interconnect location options are only available for a portion of the pixel column 352 length. FIG. 3 z illustrates that for a complex bus shape there may be four interconnect location path options along a bus 340 in a circuit column 356 having four times the width and one fourth the length of the pixel column 352 it supports. Thus, it can be seen that while the aspect ratio of the circuit column 356 is different than the aspect ratio of the pixel column 352 , the areas of the respective footprints are substantially the same or equal. As manufacturing techniques improve or design parameters change more or less area may be needed for the supporting circuits of the circuit column 356 .
FIGS. 3 v and 3 w illustrate the superimposition of the first pixel column read bus 330 with the first leg of the circuit column read bus 340 . FIG. 3 y illustrates the next, adjacent pixel column relative to the pixel column illustrated in FIG. 3 v . It should be noted that because the footprint of the circuit column 356 has an aspect ratio of 4/2, the superimposition of the pixel column bus 330 to the circuit column bus 340 requires the second leg of the circuit column bus 340 to be shaped accordingly to thereby allow a natural match or superimposition of the buses 330 and 340 with respect to the next pixel column 352 illustrated in FIGS. 3 y and 3 z FIG. 3 aa illustrates a side view of the single column of pixels and the single column of circuitry taken from FIG. 3 y showing an electrical connection therebetween.
It will be appreciated that each of the pixel columns may be shared or unshared with respect to a read bus, depending upon the conditions present that may affect pixel design and architecture. Illustrated in FIGS. 12 and 13 are two examples of pixel architecture. FIG. 12 illustrates a pixel architecture where each pixel column does not share a read bus with another pixel column. This example, when there is only one read bus per pixel column, illustrates an unshared pixel architecture. Conversely, illustrated in FIG. 13 is a horizontal 2-way pixel share. In FIG. 13 , there is only one read bus per two pixel columns. Note that the number of read buses per pixel column may be an important consideration in embodiments where the pixel array 350 is optimized on a first substrate and separated from the majority of the supporting circuitry located on a second or supporting substrate in a three dimensional stacking embodiment as discussed herein.
It should be noted that it is within the scope of the disclosure to allow for a plurality of pixel columns to correspond to a set of support circuits in a circuit column. For example, because the processing power of some support circuits may be greater than what is required by the data generated by a pixel column, a plurality of pixel columns may correspond to a circuit column. The converse is also contemplated herein, wherein certain embodiments a plurality of circuit columns may correspond to a single pixel column in a pixel array.
In an embodiment of the specific process and implementation described above, the connection may be done though an interconnect, such as a ubump, located between the two substrates/chips. Both metal layers of the two substrates/chips may face each other, therefore back side illumination may be needed on the CMOS image sensor chip comprising the pixel array (front-side of the first chip may be bonded to front-side of the second chip). In an embodiment, there may be only one interconnect used per column 352 , 356 between the first substrate/chip and the second substrate/chip. In an embodiment, two or more interconnects may be used per column 352 , 356 and may be used for redundancy purposes (process yield). Compared to conventional technology (monolithic CMOS image sensor as shown in FIGS. 3 a through 3 f ), the read bus may be broken at the edge of the pixel array and may be replicated in the second substrate/chip. A bump may then connect the two buses anywhere within the column. It will be appreciated that more interconnects, such as ubumps, may be needed for power distribution between the two or more substrates/chips or for other signals (e.g., vertical decoder).
Referring now to FIG. 4 , an embodiment of an image sensor with its pixel array and supporting circuitry built on a plurality of substrates is illustrated using backside illumination. As can be seen in the figure, a pixel array 450 may be disposed on a first substrate 452 . The first substrate 452 may be made of silicone or of another material in order to control light transmission characteristics. Solder balls, bumps or vias 421 may be used to electrically connect one substrate to another. An embodiment of a stacked image sensor may comprise a pixel array 450 on a first substrate 452 . The pixel array 450 may cover at least forty percent of a first surface 451 of the first substrate 452 . In a backside illuminated configuration, a pixel array 950 may be disposed on the backside of said first substrate 952 as illustrated best in FIG. 9 . Further, in a back side illumination configuration the substrate 452 may be thinned for controlling light transmission therethough. In an embodiment utilizing backside illumination, the first substrate may be made of primarily silicon material, or the first substrate may be made of primarily of “High-Z” semiconductor material (Cadmium Telluride e.g.), or the first substrate may be made primarily of III-V semiconductor materials (Gallium Arsenide e.g.).
In an embodiment, a pixel array 450 may cover a majority of the first surface 451 of a first substrate 452 . In such an embodiment the pixel array 450 may be situated or located on any portion of said first surface 451 . The remaining space on the first surface 451 may be used for secondary circuit placement if desired. Situations may arise where a secondary circuit may be sized such that central placement of the pixel array is not practical.
Referring now to FIG. 5 , an embodiment will be discussed wherein at least some of the supporting circuitry and components are remotely located from other supporting circuitry and components in order to work for a predetermined purpose. For some applications, it may be desirous for certain secondary processors to be more remotely located from the pixel array. For example, in a medical scope such as an endoscope there may not be enough room around the pixel array to contain all of the needed support circuitry. In such cases, the pixel array containing substrate 510 may be remotely located a distance away from other supporting substrates within the image sensor 500 .
In an embodiment, the pixel array containing substrate 510 may be adjacent to or near a support substrate 520 that is located remotely with respect to the pixel array containing substrate. The support substrate 520 may comprise an amplifier circuit thereon, while other supporting circuits may be more remotely located on another substrate 530 a distance that is farther away from the pixel array substrate 510 than the distance support substrate 520 is located away from the pixel array substrate 510 . In an embodiment the more remotely located substrate 530 may be connected to the other substrates in the image sensor 500 by wire vias 522 or may communicate wirelessly with the other substrates and circuits. Adjacent substrates may be connected to each other by way of bumps or solder balls 521 . As pixel arrays and other circuits become more efficient over time, it is within the scope of this disclosure to provide an image sensor wherein the pixel array containing substrate is more remote from all other support circuits. Such a circuit is pictured in FIG. 10 , wherein a pixel array containing substrate 1010 is more remotely located by way of vias 1022 from support substrates 1020 , 1030 , 1040 each comprising support circuits such as signal processing circuits and power circuits.
In an embodiment, the pixel array of an image sensor may dominate a large percentage of the available surface area of a first substrate 570 . As can be seen in FIG. 6 , various sized pixel arrays 572 , 574 , 576 (shown in dashed lines) are contemplated by the disclosure and fall within the scope of the design disclosed. Pixel array 576 schematically represents a configuration wherein the pixel array 576 covers a large percentage of a first substrate 570 , but yet may not cover a majority of the substrate 570 . Pixel array 576 may cover such a large percentage of the available area, even though not a majority of the area, such that at least some of the supporting circuitry may not be located on the first substrate 570 .
Pixel array 574 schematically illustrates a separate configuration from pixel array 576 and 572 , wherein the pixel array 574 covers approximately half of a first substrate 570 . Pixel array 572 schematically illustrates a separate configuration from pixel array 576 and 574 , wherein the pixel array covers a clear majority of the first substrate 570 . It should be apparent from the discussion above that the optimization process may allow for finding a pixel array size that provides the best possible image and image quality while working within constraints dictated by an application, function or purpose. Accordingly, even in an application having an imaging sensor with a fixed first substrate size, the percentage of the surface area occupied by the pixel array located on the first substrate may differ and cover many different percentages of the total surface area available on the first substrate.
Thus, it will be appreciated that the surface area that the pixel array may occupy may fall within a range that is about 25% to about 99% of the total surface area of one of the surfaces of the first substrate, or may be within a range of about 40% to about 99% of the total surface area of one of the surfaces of the first substrate, or may be within a range of about 50% to about 99% of the total surface area of one of the surfaces of the first substrate, or may be within a range of about 60% to about 99% of the total surface area of one of the surfaces of the first substrate, or may be within a range of about 70% to about 99% of the total surface area of one of the surfaces of the first substrate, or may be within a range of about 80% to about 99% of the total surface area of one of the surfaces of the first substrate, or may be within a range of about 90% to about 99% of the total surface area of one of the surfaces of the first substrate. It will be appreciated that all percentages that fall within the stated ranges are intended to fall within the scope of the disclosure. It will further be appreciated that all sub-ranges falling within the range of about 25% to about 99% of the total surface area of one of the surfaces of the first substrate are intended to fall within the scope of the disclosure.
Because of the nature of a backside illuminated pixel array, the substrate surfaces discussed above may be extraneous to an image sensor comprising a backside illuminated pixel array. Thus, in backside illuminated applications, the substrate surface may be eliminated or formed integrally with the pixel array.
Pixel array coverage or surface area may be within a range of about 40% to about 70% of the total surface area of the substrate upon which the pixel array resides, and in such cases it may be possible to place some support circuitry thereon without diminishing from the design of the image sensor. In an embodiment, a light emitting circuit may occupy some space on the first substrate to provide light during use. For many applications, where dimensions are extremely tight and are the most tightly constrained, an optimized imaging sensor may cover 90% or more, up to substantially all of a surface area of a first substrate. It should be noted that it is within the scope of this disclosure to contemplate a pixel array having an integrated substrate therein rather than being added to a substrate.
Illustrated in FIG. 7 is an embodiment of an imaging sensor having a plurality of pixel arrays. As can be seen in the figure, an image sensor 700 may comprise a first image sensor 710 and a second image sensor 711 , which are in electrical communication with a substrate 715 or a plurality of substrates that may be stacked vertically or otherwise with respect to an object to be imaged. In an embodiment, supporting circuits may be remotely located on subsequent or supporting substrates as discussed above. Such a configuration may be desirable for three dimensional image capture, wherein the two pixel arrays may be off set during use. In another embodiment, a first pixel array and a second pixel array may be dedicated to receiving a predetermined range of wave lengths of electromagnetic radiation, wherein the first pixel array is dedicated to a different range of wave length electromagnetic radiation than the second pixel array.
It will be appreciated that the structures and apparatuses disclosed herein are merely exemplary for optimizing an imaging sensor, and it should be appreciated that any structure, apparatus or system for optimizing an image sensor, which performs functions the same as, or equivalent to, those disclosed herein are intended to fall within the scope of this disclosure, including those structures, apparatuses or systems for imaging, which are presently known, or which may become available in the future. Anything which functions the same as, or equivalently to, a means for optimizing an imaging sensor falls within the scope of this disclosure.
Those having ordinary skill in the relevant art will appreciate the advantages provide by the features of the disclosure. For example, it is a potential feature of the disclosure to provide an optimized imaging sensor, which is simple in design and manufacture. Another potential feature of the disclosure is to provide such an imaging sensor with larger pixels relative to overall size.
In the foregoing Detailed Description, various features of the disclosure are either grouped together in a single embodiment for the purpose of streamlining the disclosure or are discussed in different embodiments. This method of disclosure is not to be interpreted as reflecting an intention that the claimed disclosure requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment and various inventive features disclosed in separate embodiments may be combined to form its own embodiment as claimed more fully below. Thus, the following claims are hereby incorporated into this Detailed Description by this reference, with each claim standing on its own as a separate embodiment of the disclosure.
It is to be understood that the above-described arrangements are only illustrative of the application of the principles of the disclosure. Numerous modifications and alternative arrangements may be devised by those skilled in the art without departing from the spirit and scope of the disclosure and the appended claims are intended to cover such modifications and arrangements. Thus, while the disclosure has been shown in the drawings and described above with particularity and detail, it will be apparent to those of ordinary skill in the art that numerous modifications, including, but not limited to, variations in size, materials, shape, form, function and manner of operation, assembly and use may be made without departing from the principles and concepts set forth herein.