Photosensitive imaging devices and associated methods

(Cross-reference to related applications) This application is based on U.S. Provisional Patent Application No. 61/243,434 (filed September 17, 2009), U.S. Provisional Patent Application No. 61/311,004 (filed March 5, 2010), and U.S. Claims the benefit of Provisional Patent Application No. 61/311,107 (filed March 5, 2010), each of which is incorporated herein by reference.

(Background) The interaction of light and semiconductor materials has become an important innovation. Silicon image sensors are used in a variety of technologies such as digital cameras, optical mice, video cameras, and mobile phones. Charge-coupled devices (CCDs) are widely used in digital imaging and were later improved by complementary metal-oxide-semiconductor (CMOS) imagers with improved performance. CMOS sensors are typically manufactured from silicon and convert visible incident light into a photocurrent that can ultimately be converted into a digital image. However, silicon-based techniques for detecting infrared incident electromagnetic radiation are problematic because silicon is an indirect bandgap semiconductor with a bandgap of approximately 1.1 eV. Therefore, the absorption of electromagnetic radiation with wavelengths above about 1100 nm is very low in silicon.

<p>The present disclosure provides photosensitive devices and related methods. In one aspect, for example, a photosensitive imaging device includes a plurality of doped regions forming at least one junction, a textured region coupled to a semiconductor substrate and positioned to interact with electromagnetic radiation, and a semiconductor substrate. and an electrically conductive element coupled to and operable to conduct an electrical signal from the at least one junction. In one aspect, the textured region is operable to facilitate generation of an electrical signal from detection of infrared electromagnetic radiation. In another aspect, interacting with the electromagnetic radiation further includes increasing an effective absorption length of the semiconductor substrate as compared to a semiconductor substrate lacking the textured region. In one specific aspect, the conductive element is selected from the group consisting of a transistor, a sensing node, a conductive gate, and combinations thereof.</p><p>The textured region can be placed at various locations relative to the doped region. In one aspect, for example, a textured region is disposed on a surface of a semiconductor substrate opposite the plurality of doped regions. In one particular aspect, the textured region has a surface morphology operable to direct electromagnetic radiation into or from the semiconductor substrate. The surface morphology of the textured region for a semiconductor substrate can include a variety of configurations including, but not limited to, sloped, pyramidal, inverted pyramid, spherical, parabolic, asymmetric, symmetric, etc., including combinations thereof.</p><p>In another aspect, a textured region can be disposed on a surface of a semiconductor substrate adjacent to a plurality of doped regions. In a more specific aspect, additional textured regions can be disposed on a surface of the semiconductor substrate opposite the plurality of doped regions. Thus, in this manner, the textured region can be located adjacent to and opposite the plurality of doped regions.</p><p>Various aspects of the textured region may be variable depending on the desired configuration of the device. However, in one aspect, the textured region includes surface features having a size selected from the group consisting of micron-sized, nano-sized, and combinations thereof. Numerous surface feature forms are envisioned, non-limiting examples of which include cones, pillars, pyramids, microlenses, quantum dots, inverted features, and combinations thereof. Additionally, textured regions can be formed by various processes. Non-limiting examples of such texturing processes can include lasing, chemical etching (eg, anisotropic etching, isotropic etching), nanoimprinting, material deposition, and combinations thereof.</p><p>Additional layers and/or structures can be included within various devices according to aspects of the present disclosure. In one aspect, for example, a reflective layer can be coupled to a semiconductor substrate and positioned to retain electromagnetic radiation within the semiconductor substrate. In another aspect, a lens can be optically coupled to the semiconductor substrate and positioned to focus incident electromagnetic radiation into the semiconductor substrate.</p><p>In another aspect of the disclosure, a method of making a photosensitive imaging device is provided. Such a method includes forming a textured region on a semiconductor substrate having a plurality of doped regions forming at least one junction, the textured region being formed at a location to interact with electromagnetic radiation. and coupling the electrically conductive element to the semiconductor substrate such that the electrically conductive element is operable to conduct an electrical signal from the at least one junction.</p><p>In one aspect, the photosensitive imaging device can be tuned to select specific electromagnetic radiation wavelengths to filter. In one specific aspect, the tuning step includes forming a surface feature with dimensions that selectively diffuse or selectively absorb electromagnetic radiation of a desired wavelength. In another aspect, the tuning step includes emplacement of the textured region, material type and/or thickness of the textured region, dopant type of the textured region, doping profile of the textured region, dopant profile of the semiconductor substrate, semiconductor substrate material type and/or thickness, and combinations thereof.</p><p>In another aspect of the present disclosure, a photosensitive imaging device is provided. Such a device includes: a semiconductor substrate having a plurality of doped regions forming at least one junction; a textured region coupled to the semiconductor substrate and arranged to interact with electromagnetic radiation; and at least four transistors coupled to the at least one junction, at least one of the transistors being electrically coupled to the at least one junction.</p>

<figref num="1">FIG. 1 is a schematic diagram of a photosensitive element according to one aspect of the present disclosure.</figref><figref num="2">FIG. 2 is a schematic diagram of a photosensitive element according to another aspect of the present disclosure.</figref><figref num="3">FIG. 3 is a schematic diagram of a photosensitive element according to yet another aspect of the present disclosure.</figref><figref num="4">FIG. 4 is a schematic diagram of a photosensitive element according to a further aspect of the present disclosure.</figref><figref num="5">FIG. 5 is a schematic illustration of a photosensitive element, according to yet a further aspect of the present disclosure.</figref><figref num="6">FIG. 6 is a schematic diagram of a photosensitive element according to another aspect of the present disclosure.</figref><figref num="7">FIG. 7 is a schematic diagram of a photosensitive pixel element according to yet another aspect of the present disclosure.</figref><figref num="8">FIG. 8 is a schematic diagram of a photosensitive pixel element according to a further aspect of the present disclosure.</figref><figref num="9">FIG. 9 is a schematic illustration of a photosensitive pixel element, according to still further aspects of the present disclosure.</figref><figref num="10">FIG. 10 is a schematic diagram of a photosensitive pixel element according to another aspect of the present disclosure.</figref><figref num="11">FIG. 11 is a schematic diagram of a photosensitive pixel element according to yet another aspect of the present disclosure.</figref><figref num="12">FIG. 12 is a schematic diagram of a photosensitive pixel element according to a further aspect of the present disclosure.</figref><figref num="13">FIG. 13 is a schematic diagram of a photosensitive pixel element according to another aspect of the present disclosure.</figref><figref num="14">FIG. 14 is a schematic diagram of a photosensitive imaging device according to yet another aspect of the present disclosure.</figref><figref num="15">FIG. 15 is a schematic diagram of a photosensitive pixel element according to a further aspect of the present disclosure.</figref><figref num="16">FIG. 16 is a schematic diagram of a photosensitive pixel element according to another aspect of the present disclosure.</figref><figref num="17">FIG. 17 is a depiction of a method of making a photosensitive imaging device, according to yet another aspect of the present disclosure.</figref>

Before this disclosure is described herein, it is understood that this disclosure is not limited to the particular structures, process steps, or materials disclosed herein, and that equivalents thereof will be recognized by those skilled in the art. Please understand that it also extends to things. It should also be understood that the terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting.

(Definitions) The following terms will be used in accordance with the definitions set forth below.

Note that as used in this specification and the appended claims, the singular forms "a" and "the" include plural references unless the context clearly dictates otherwise. . Thus, for example, reference to a "dopant" includes one or more such dopants, and reference to a "layer" includes reference to one or more such layers.

As used herein, the term "low oxygen content" refers to any material that has an interstitial oxygen content of about 60 ppm atoms or less.

As used herein, the terms "irregular surface" and "textured surface" can be used interchangeably and refer to nano- to micron-sized surface variations formed by irradiation with laser pulses. refers to a surface that has a topology. The characteristics of such surfaces can be variable depending on the materials and techniques employed, but in one aspect such surfaces can be hundreds of nanometers thick and contain nanocrystals (e.g. , about 10 to about 50 nanometers) and nanopores. In another aspect, such a surface can include micron-sized structures (eg, about 2 μm to about 60 μm). In yet another aspect, the surface can include nano- and/or micron-sized structures from about 5 nm to about 500 μm.

As used herein, the term "fluence" refers to the amount of energy from a single pulse of laser radiation that passes through a unit area. In other words, "fluence" can be described as the energy density of one laser pulse.

As used herein, the terms "surface modification step" and "surface modification" refer to the modification of the surface of a semiconductor material using laser radiation. In one specific aspect, surface modification may primarily include a process using laser radiation or a combination of laser radiation and a dopant, whereby the laser radiation causes incorporation of the dopant into the surface of the semiconductor material. Facilitate. Thus, in one aspect, surface modification includes doping of the semiconductor material.

As used herein, the term "target region" refers to the area of semiconductor material that is intended to be doped or modified using laser radiation. The target area of the semiconductor material may be variable as the surface modification process progresses. For example, after a first target region is doped or surface modified, a second target region may be selected on the same semiconductor material.

As used herein, the term "detection" refers to sensing, absorbing, and/or collecting electromagnetic radiation.

As used herein, the term "substantially" refers to the complete or nearly complete extent or degree of an action, feature, property, condition, structure, article, or result. For example, an object that is "substantially" encapsulated would mean that the object is either completely encapsulated or nearly completely encapsulated. The precise degree of permissible deviation from absolute perfection may depend, in some cases, on the specific circumstances. However, in general, a completeness analogy will have the same overall result as if absolute and total completeness were obtained. The use of "substantially" is equally applicable when used in a negative sense, referring to the completeness or near-completeness of an action, feature, property, condition, structure, article, or result. be. For example, ``A composition that is substantially particle-free is completely devoid of particles, or is almost completely devoid of particles, so that the result is the same as if it were completely devoid of particles.'' In other words, a composition that is "substantially free" of an ingredient or element may still contain such an article unless there is, in fact, a measurable effect thereof. good.

As used herein, the term "about" refers to the endpoints of a numerical range by assuming that a given value may be "slightly above" or "slightly below" the endpoints. used to provide flexibility.

As used herein, multiple articles, structural elements, compositional elements, and/or materials may be presented as a common list for convenience. However, these lists should be construed such that each member of the list is individually identified as a separate and unique member. Thus, any individual member of such a list is effectively equivalent to any other member of the same list based solely on their presentation in a common group, without any indication to the contrary. should not be construed as such.

Concentrations, amounts, and other numerical data may be expressed or presented herein in range format. Such a range format is used solely for convenience and brevity, and therefore, not only the numbers explicitly listed as limits of the range, but also each number and subrange explicitly listed. It is to be understood that the range should be interpreted flexibly to include all individual numerical values and subranges subsumed within the same range. By way of illustration, a numerical range of "about 1 to about 5" includes not only the explicitly recited values of about 1 to about 5, but also includes individual values and subranges within the recited range. should be interpreted. Therefore, this numerical range includes 2, 3, and 4, subranges such as 1-3, 2-4, and 3-5, and individual values such as 1, 2, 3, 4, and 5. Included separately.

This same principle applies to ranges that recite only one numerical value as a minimum or maximum value. Moreover, such interpretations should apply regardless of the full breadth of the scope or features described.

DISCLOSURE Electromagnetic radiation can exist over a wide range of wavelengths, including visible wavelengths (about 350 nm to 800 nm) and non-visible wavelengths (greater than about 800 nm or shorter than 350 nm). The infrared spectrum often includes a near-infrared portion of the spectrum, which includes wavelengths from about 800 to 1300 nm, a short-wave infrared portion of the spectrum, which includes wavelengths from about 1300 nm to 3 micrometers, and a near-infrared portion of the spectrum, which includes wavelengths from about 1300 nm to 3 micrometers, and from greater than about 3 micrometers to about 30 micrometers. It is described to include the medium to longwave infrared (also thermal infrared) portion of the spectrum, including wavelengths of meters. These are generally and collectively referred to herein, unless indicated otherwise, as the "infrared" portion of the electromagnetic spectrum.

Conventional silicon photodetection imaging devices have limited light absorption/detection characteristics. For example, infrared light is nearly transparent to such silicon-based detectors. Although other materials (e.g., InGaAs) can be used to detect infrared electromagnetic radiation with wavelengths greater than about 1000 nm, silicon is relatively inexpensive to manufacture and is suitable for use in the visible spectrum (i.e., It is still commonly used because it can be used to detect wavelengths within visible light (350nm-800nm). Conventional silicon materials require substantial absorption depth to detect photons with wavelengths greater than about 700 nm. Although visible light can be absorbed at relatively shallow depths within silicon, there is no absorption at longer wavelengths (e.g., 900 nm) in silicon at standard wafer depths (e.g., approximately 750 μm). However, it is defective. The devices of the present disclosure increase the absorption of semiconductor materials by shortening the effective absorption length to longer wavelengths compared to conventional materials. For example, the absorption depth of silicon can be reduced such that these longer wavelengths can be absorbed at depths of about 850 μm or less. In other words, by reducing the effective absorption length, these devices are able to absorb longer wavelengths (eg, &gt;1000 nm for silicon) in thin semiconductor materials. In addition to increasing the effective absorption length , the response rate or speed can also be increased by using thinner semiconductor materials.

In addition, the present disclosure provides broadband photosensitive diodes, pixels, and imaging devices capable of detecting visible and infrared electromagnetic radiation, and includes related methods of making such devices. The photosensitive diode includes a semiconductor substrate having a plurality of doped regions forming at least one junction and at least one textured region coupled to the semiconductor substrate and positioned to interact with electromagnetic radiation. be able to. In one aspect, the plurality of doped regions can include at least one cathode region and at least one anode region. In some aspects, the doped region can include n-type dopants and/or p-type dopants, as described below, thereby creating a p-n junction. In another aspect, the photosensitive element can include an i-type region to form a pin junction.

The photosensitive pixel includes: a semiconductor substrate having a plurality of doped regions forming at least one junction; a textured region coupled to the at least one semiconductor substrate and positioned to interact with electromagnetic radiation; and an electrically conductive element coupled to the substrate and operable to conduct an electrical signal from the at least one junction. A photosensitive image sensor can include multiple photosensitive pixels. Additionally, electrically conductive elements can include a variety of devices including, but not limited to, transistors, sensing nodes, conducting gates, conducting electrodes, and the like.

A photosensitive or photosensitive imager includes a photodiode or pixel capable of absorbing electromagnetic radiation within a given wavelength range. Such image sensors may be passive pixel sensors (PPS), active pixel sensors (APS), digital pixel sensor imagers (DPS), etc., but one difference is that the image sensor It is to read out the structure. For example, a semiconductor photosensitive imager can be a three or four transistor active pixel sensor (3T APS or 4T APS). Various additional components are also contemplated and will, of course, be variable depending on the particular configuration and intended results. As an example, the 4T configuration may additionally include a conduction gate, reset, source follower, and row select transistor, among others. Additionally, devices with more than four transistors are also within the scope.

Photosensitive imaging devices can be front-illuminated (FSI) or back-illuminated (BSI) devices, and there are advantages and disadvantages to both construction types. In a typical FSI imager, incident light first enters the semiconductor device by passing through transistors and metal circuitry. However, the light can scatter from the transistors and circuitry before entering the light sensing portion of the imager, thus creating optical losses and noise. A lens is placed above the FSI pixel to direct and focus the incident light onto the light sensitive active area of the element, thus allowing it to partially bypass the circuitry. In one aspect, the lens can be a U-shaped lens. BSI imagers, on the other hand, are configured with a junction depletion region extending on opposite sides of the device. In one aspect, for example, incident light enters the element via the light-sensing portion and is mostly absorbed before reaching the circuit. The BSI design allows for smaller pixel structures and high fill factors for imagers. As mentioned above, the present disclosure can be adapted to either configuration. It should also be appreciated that devices according to aspects of the present disclosure can be incorporated within complementary metal oxide semiconductor (CMOS) or charge coupled device (CCD) imager structures.

In one aspect, as shown in FIG. 1, a photosensitive diode 10 includes a semiconductor substrate 12 having a plurality of doped regions 14, 16 forming at least one junction and coupled to the semiconductor substrate to transmit and interact with electromagnetic radiation. and at least one textured area 18 operatively arranged. Different doped regions can have the same doping profile or different doping profiles depending on the device. Such a structure is an FSI design, where light enters the semiconductor substrate from the direction of multiple doped regions. Note that although the device shown in FIG. 1 contains three doped regions, aspects containing more than one doped region are also contemplated within the present scope. Additionally, in some aspects, a semiconductor substrate can be doped and therefore be considered a doped region. It should also be noted that the photosensitive diode can be configured with the BSI structure, so the electromagnetic radiation will enter the semiconductor substrate from the direction of the textured area.

Various devices according to aspects of the present disclosure can exhibit increased quantum efficiency over conventional photosensitive devices. Any increase in quantum efficiency makes a large difference in signal-to-noise ratio. More complex structures can provide not only increased quantum efficiency but also better pixel-to-pixel uniformity. Additionally, the devices of the present disclosure exhibit increased responsivity compared to conventional photosensitive devices. For example, in one aspect, the responsivity can be greater than or equal to 0.8 A/W for wavelengths greater than 1000 nm for semiconductor substrates less than 100 μm thick.

The photosensitive imaging element can be held under constant conditions (fixed voltage or current) to provide improved linearity and uniformity. Connections between the imager and the underlying device layers can be achieved using vias fabricated from refractory metals such as tungsten or tantalum. Various light effects may be provided by placing a storage element below the imaging element. For example, the entire pixel array may be dedicated to signal processing. This may enable higher performance by allowing access to low level pixel signals. Additionally, massively parallel operations can be performed by the pixel processor. For example, analog-to-digital conversion, noise reduction (ie, true correlated double sampling), power adjustment, nearest-neighbor pixel processing, compression, fusion, and color multiplexing operations can be performed.

A variety of semiconductor materials are envisioned for use in conjunction with devices and methods according to aspects of the present disclosure. Non-limiting examples of such semiconductor materials include Group IV materials, compounds and alloys of materials from Groups II and VI, compounds and alloys of materials from Groups III and V, and Can include combinations thereof. More specifically, exemplary Group IV materials can include silicon, carbon (eg, diamond), germanium, and combinations thereof. Various exemplary combinations of Group IV materials may include silicon carbide (SiC) and silicon germanium (SiGe). In one specific aspect, the semiconductor material can be or include silicon. Exemplary silicon materials can include amorphous silicon (a-Si), microcrystalline silicon, polycrystalline silicon, and nanocrystalline silicon, as well as other crystal types. In another aspect, the semiconductor material can include at least one of silicon, carbon, germanium, aluminum nitride, gallium nitride, indium gallium arsenide, aluminum gallium arsenide, and combinations thereof.

Exemplary combinations of Group II-VI materials include cadmium selenide (CdSe), cadmium sulfide (CdS), cadmium telluride (CdTe), zinc oxide (ZnO), zinc selenide (ZnSe), zinc sulfide (ZnS). , zinc telluride (ZnTe), cadmium zinc telluride (CdZnTe, CZT), mercury cadmium telluride (HgCdTe), mercury zinc telluride (HgZnTe), mercury zinc selenide (HgZnSe), and combinations thereof. can.

Exemplary combinations of III-V materials include aluminum antimonide (AlSb), aluminum arsenide (AlAs), aluminum nitride (ΑlΝ), aluminum phosphide (AlP), boron nitride (BN), boron phosphide (BP). ), boron arsenide (BAs), gallium antimonide (GaSb), gallium arsenide (GaAs), gallium nitride (GaN), gallium phosphide (GaP), indium antimonide (InSb), indium arsenide (InAs), nitride Indium (InN), Indium phosphide (InP), Aluminum gallium arsenide (AlGaAs, AlxGa1-xAs), Indium gallium arsenide (InGaAs, InxGa1-xAs), Indium gallium phosphide (InGaP), Aluminum gallium arsenide (AlInAs) ), aluminum indium antimonide (AllnSb), gallium arsenide nitride (GaAsN), gallium arsenide phosphide (GaAsP), aluminum gallium nitride (AlGaN), aluminum gallium phosphide (AlGaP), indium gallium nitride (InGaN), Indium antimonide arsenide (InAsSb), Indium gallium antimonide (InGaSb), Indium aluminum gallium phosphide (AlGalnP), Aluminum gallium arsenide phosphide (AlGaAsP), Indium gallium arsenide phosphide (InGaAsP), Phosphide arsenide Aluminum indium (AlInAsP), aluminum gallium arsenide nitride (AlGaAsN), indium gallium arsenide nitride (InGaAsN), indium aluminum arsenide nitride (InAlAsN), gallium antimony arsenide nitride (GaAsSbN), gallium indium arsenide antimonide nitride (GalnNAsSb), gallium indium arsenide antimonide phosphide (GalnAsSbP), and combinations thereof.

The semiconductor material can be any thickness that allows electromagnetic radiation detection and conversion functionality, and therefore any such thickness of semiconductor material is considered to be within this range. In some aspects, the laser treated regions of the semiconductor increase the efficiency of the device so that the semiconductor material can be thinner than previously possible. Reducing semiconductor thickness reduces the amount of semiconductor material required to fabricate such devices. In one aspect, for example, the semiconductor material has a thickness of about 500 nm to about 50 μm. In another aspect, the semiconductor material has a thickness of about 500 μm or less. In yet another aspect, the semiconductor material has a thickness of about 1 μm to about 10 μm. In a further aspect, the semiconductor material can have a thickness of about 5 μm to about 750 μm. In yet a further aspect, the semiconductor material can have a thickness of about 5 μm to about 100 μm.

Additionally, various types of semiconductor materials are contemplated, and any such material that can be incorporated into an electromagnetic radiation detection element is considered within the present scope. In one aspect, for example, the semiconductor material is single crystalline. In another aspect, the semiconductor material is polycrystalline. In yet another aspect, the semiconductor material is microcrystalline. It is also assumed that the semiconductor material may be amorphous. Specific non-limiting examples include amorphous silicon or amorphous selenium.

The semiconductor materials of the present disclosure can also be made using a variety of manufacturing processes. In some cases, manufacturing procedures can affect the efficiency of the device and may be considered to achieve desired results. Exemplary manufacturing processes may include a Czochralski (Cz) process, a magnetic Czochralski (mCz) process, a floating zone (FZ) process, an epitaxial growth or evaporation process, and the like. Whether a low oxygen content is desired within the device can also influence the selection of a manufacturing process for the semiconductor material. Various processes produce semiconductor materials containing variable amounts of oxygen, and therefore some applications with tighter tolerances to oxygen levels benefit more from specific manufacturing procedures compared to others. may be enjoyed. For example, during CZ crystal growth, oxygen from a containment vessel (usually a quartz crucible) can be incorporated into the crystal as it is drawn. In addition, other sources of oxygen contamination are also possible with the CZ process. However, such contamination may be reduced through the use of non-oxygen-containing crucible materials as well as the development of other crystal growth methods that do not utilize crucibles. One such process is the FZ process.

Material growth by the CZ method can also be performed with low oxygen concentrations through modifications to the crystal growth process, such as growing crystals in the presence of a magnetic field (ie, the mCz process). Also, gettering techniques can be employed to reduce the effect of oxygen or other impurities on the finished device. These gettering techniques can include thermal cycling to liberate or nucleate impurities, or selective ion implantation of species that serve as gettering sites for impurities. For example, oxygen concentrated in the semiconductor can be removed by performing furnace cycling and forming a depletion zone. During heating with an inert gas, oxygen near the surface of the semiconductor diffuses out of the material. During furnace cycling, however, a nucleation and growth step may be performed after the depletion step. Nucleation sites for the precipitate are formed during the nucleation step, and precipitates are grown from the nucleation sites during the growth step. Precipitates are formed from interstitial oxygen within the bulk of the semiconductor material and below the depletion zone. Precipitation of oxygen within the bulk of the semiconductor material may be desired because such precipitates can act as gettering sites. Such precipitate formation can also be performed to "trap" interstitial oxygen within the precipitate, reducing the possibility that such oxygen will migrate from the bulk of the semiconductor material into the depletion zone. .

In those aspects where low oxygen content of the device is desired, further processing of the semiconductor material can be performed to minimize the introduction of oxygen. Oxygen may be present in different states or at different sites (eg, interstitial or substitutive) within a semiconductor, such as silicon, depending on the heat treatment the semiconductor has undergone. When a semiconductor is exposed to temperatures above about 1000° C., for example, oxygen can form aggregates or aggregates that act as defect sites within the crystal lattice. These sites can lead to trapped conditions, which can result in shortened carrier lifetimes within semiconductor materials and devices. At lower temperatures (eg, about 400°C to 700°C), oxygen can behave as an electrically active heat donor. Therefore, oxygen can have a negative impact on carrier lifetime and carrier mobility. In devices fabricated to have photoconductive gain, the presence of oxygen, which causes a reduction in carrier lifetime, may result in a reduction in the level of photoconductive gain.

Therefore, it may be beneficial to produce semiconductor devices such that low oxygen content is obtained or maintained. This begins with processing the material to minimize the absorption of oxygen into the semiconductor lattice, the use of semiconductors that have low levels of oxygen contained within them, and the use of semiconductors that This can be accomplished in a variety of ways, including the use of oxygen exclusion or reduction techniques. Such processes and techniques can include, for example, annealing the semiconductor material and any laser-processed regions to a lower temperature compared to previous annealing procedures. The annealing process is discussed more fully below.

Additionally, the texturing and/or optional annealing process of the semiconductor material can be performed in a substantially oxygen-deficient environment to minimize the introduction of oxygen into the semiconductor. An oxygen-deficient or substantially oxygen-deficient environment can include a variety of environments. In one aspect, for example, an oxygen-deficient environment may be an environment in which oxygen from air or other sources is replaced with a gas or other fluid containing little or no oxygen. In another aspect, the processing can occur in a vacuum environment and thus contain little or no oxygen. In addition, oxygen-containing materials or materials that introduce oxygen into semiconductors, such as quartz crucibles, may be avoided. Indeed, the term "oxygen-deficient environment" can be used to describe an environment with low levels of oxygen, provided that the semiconductor material is processed within the desired tolerances. It is assumed that you can. Thus, an environment with low oxygen, or with little or no oxygen, is one in which a semiconductor can be treated as a low oxygen content semiconductor while retaining oxygen levels within the tolerances of the present disclosure. . In one aspect, an anoxic environment can be an anoxic environment. Further details regarding low oxygen content semiconductor materials can be found in US patent application Ser. No. 12/771,848, filed April 30, 2010, which is incorporated herein by reference.

The semiconductor material can have variable levels of interstitial oxygen depending on the desired effectiveness of the device. In some aspects, oxygen content may not matter, so any level of oxygen within the lattice is acceptable. In other aspects, low oxygen content is desired. In one aspect, the semiconductor material can have an oxygen content of about 50 ppm atoms or less. In another aspect, the semiconductor material can have an oxygen content of about 30 ppm atoms or less. In yet another aspect, the semiconductor material can have an oxygen content of about 10 ppm atoms or less. In another aspect, the semiconductor can have an oxygen content of less than about 5 ppm atoms. In yet another aspect, the semiconductor can have an oxygen content of less than about 1 ppm atoms.

As mentioned above, the textured regions can function to diffuse electromagnetic radiation, redirect electromagnetic radiation, absorb electromagnetic radiation, and thus increase the quantum efficiency of the device. The textured region can include surface features that increase the effective absorption length of the photosensitive pixel. Surface features can be cones, pyramids, pillars, protrusions, microlenses, quantum dots, inverted features, etc. Factors such as manipulation of feature size, dimensions, material type, dopant profile, texture location, etc. allow the diffusive region to be tuned to specific wavelengths. In one aspect, tuning the device enables absorption at a specific wavelength or range of wavelengths. In another aspect, tuning the element allows specific wavelengths or ranges of wavelengths to be reduced or eliminated through filtering.

Tuning can also be achieved through the location of textured regions within the device, modification of the dopant profile of regions within the device, dopant selection, and the like. Additionally, the material composition near the textured region can produce wavelength-specific light-sensitive pixel elements. Note that the wavelength-specific light sensitive pixels can be different from one pixel to the next and can be incorporated within the imaging array. For example, a 4x4 array can include a blue pixel, a green pixel, a red pixel, and an infrared light absorbing pixel, or a blue pixel, two green pixels, and a red pixel.

Textured regions according to aspects of the present disclosure allow the photosensitive element to be exposed to multiple passes of incident electromagnetic radiation within the element, particularly at longer wavelengths (ie, infrared). Such internal reflection increases the effective absorption length over the thickness of the semiconductor substrate. This increase in absorption length increases the quantum efficiency of the device, leading to improved signal-to-noise ratio.

Textured regions can be formed by a variety of techniques, including lasing, chemical etching (eg, anisotropic etching, isotropic etching), nanoimprinting, additive material deposition, and the like. For example, pillar features can be incorporated into pixels by thinning or removing material from the back side of the FSI semiconductor substrate by using deep trench isolation and etching techniques. In one aspect, material can be removed to a thickness of about 20 μm. Anisotropic etching can be used to produce sloped back pyramid structures, spherical structures, parabolic structures, lens structures with reflectors, etc. Such features on the back of the pillars would also serve to diffuse and reflect electromagnetic radiation.

In one aspect, the texturing process can be performed during fabrication of the photosensitive element. In another aspect, the texturing process can be performed on a prefabricated photosensitive element. For example, CMOS, CCD, or other photosensitive elements can be textured after manufacture. In this case, the material layer may be removed from the photosensitive element to expose the semiconductor substrate or bulk material on which the textured region may be formed.

One effective method of producing textured areas is through laser processing. Such laser processing allows texturing of discrete locations on the semiconductor substrate. Various techniques of laser processing to form textured regions are contemplated, and any technique capable of forming such regions should be considered within the present scope. Laser treatment or processing makes it possible, inter alia, to improve absorption properties and thus increase electromagnetic radiation focusing and detection. The laser treated area can be associated with the surface closest to the impinging electromagnetic radiation, or the laser treated surface can be associated with the opposite surface to the impinging electromagnetic radiation, whereby the laser treated area can be associated with the surface opposite to the impinging electromagnetic radiation. allows the radiation to pass through the semiconductor material before impinging on the exposed area.

In one aspect, for example, a target area of semiconductor material can be irradiated with laser radiation to form a textured area. Examples of such processing are described in further detail in US Pat. In summary, a surface of a semiconductor material is irradiated with laser radiation to form a textured or surface modified region. Such laser processing can occur with or without dopant materials. In those aspects where dopants are used, the laser can be directed through the dopant carrier and onto the semiconductor surface. In this way, dopants from the dopant carrier are introduced into the target region of the semiconductor material. Such regions incorporated within the semiconductor material may have various effects according to aspects of the present disclosure. For example, the target area typically has a textured surface that increases the surface area of the laser treated area and increases the probability of radiation absorption through the mechanisms described herein. In one aspect, such target area is a substantially textured surface that includes micron-sized and/or nano-sized surface features produced by laser texturing. In another aspect, irradiating the surface of the semiconductor material includes exposing the dopant to laser radiation such that the irradiation incorporates the dopant into the semiconductor. Various dopant materials are well known in the art and are discussed in more detail herein.

Thus, the surface of a semiconductor material is chemically and/or structurally modified by laser treatment, including in some aspects the formation of surface features as microstructures or patterned areas on the surface, and dopants. If used, it may result in the incorporation of such dopants into the semiconductor material. In some aspects, the features or microstructures can be about 50 nm to 20 μm in size and can assist in absorbing electromagnetic radiation. In other words, a textured surface can increase the probability of incident radiation being absorbed by the semiconductor material.

The type of laser radiation used to surface modify semiconductor materials can be variable, depending on the material and the intended modification. Any laser radiation known in the art can be used in conjunction with the devices and methods of the present disclosure. However, it is possible to influence the surface modification process and/or the resulting products, including, but not limited to, the wavelength of the laser radiation, pulse width, pulse fluence, pulse frequency, polarization, direction of laser propagation relative to the semiconductor material, etc. There are several unique laser characteristics. In one aspect, a laser can be configured to provide pulsed lasing of a semiconductor material. Short pulse lasers are those capable of producing femtosecond, picosecond, and/or nanosecond pulse durations. The laser pulse can have a center wavelength within the range of about 10 nm to about 8 μm, and more specifically, about 200 nm to about 1200 nm. The pulse width of the laser radiation can range from about ten femtoseconds to about several hundred nanoseconds. In one aspect, the laser pulse width can be in the range of about 50 femtoseconds to about 50 picoseconds. In another aspect, the laser pulse width can range from about 50 picoseconds to 100 nanoseconds. In another aspect, the laser pulse width can range from about 50 to 500 femtoseconds.

The number of laser pulses that irradiate the target area can range from about 1 to about 2000. In one aspect, the number of laser pulses irradiating the semiconductor target area can be from about 2 to about 1000. Additionally, the repetition rate or frequency of the pulses can be selected to be in the range of about 10 Hz to about 10 μHz, or in the range of about 1 kHz to about 1 MHz, or in the range of about 10 Hz to about 1 kHz. Additionally, the fluence of each laser pulse can range from about 1 kJ/m2 to about 20 kJ/m2, or from about 3 kJ/m2 to about 8 kJ/m2.

A variety of dopant materials are envisioned, and any such material that can be used in a laser treatment process to surface modify a semiconductor material in accordance with aspects of the present disclosure is considered within the present scope. Note that the particular dopants utilized can vary depending on the laser treated semiconductor material as well as the intended use of the resulting semiconductor material. For example, the selection of potential dopants may vary depending on whether tuning of the photosensitive element is desired.

Dopants can be either electron donating or hole donating. In one aspect, non-limiting examples of dopant materials can include S, F, B, P, N, As, Se, Te, Ge, Ar, Ga, In, Sb, and combinations thereof. Note that the scope of dopant materials should include not only the dopant materials themselves, but also the materials in the form that deliver such dopants (ie, the dopant carrier). For example, the S dopant material includes not only S, but also any material that can be used to dope the target region with S, such as H2S, SF6, SO2, etc., including combinations thereof, for example. In one specific aspect, the dopant can be S. Sulfur can be present at an ionic dosage level between about 5x1014 and about 1x1016 ions/cm2. Non-limiting examples of fluorine-containing compounds include ClF3, PF5, F2SF6, BF3, GeF4, WF6, SiF4, HF, CF4, CHF3, CH2F2, CH3F, C2F6, C2HF5, C3F8, C4F8, NF3, including combinations thereof. etc. can be included. Non-limiting examples of boron-containing compounds can include B(CH3)3, BF3, BCl3, BN, C2B10H12, borosilicate, B2H6, etc., including combinations thereof. Non-limiting examples of phosphorus-containing compounds can include PF5, PH3, etc., including combinations thereof. Non-limiting examples of chlorine-containing compounds can include Cl2, SiH2Cl2, HCl, SiCl4, etc., including combinations thereof. Dopants can also include arsenic-containing compounds such as AsH3, antimony-containing compounds, and the like. Additionally, the dopant materials can include mixtures or combinations across the group of dopants, ie, sulfur-containing mixtures mixed with chlorine-containing compounds. In one aspect, the dopant material can have a density greater than that of air. In one specific aspect, the dopant material can include Se, H2S, SF6, or mixtures thereof. In yet another specific aspect, the dopant can be SF6 and can have a predetermined concentration range of about 5.0x10-8 mol/cm3 to about 5.0x10-4 mol/cm3. SF6 gas is a good carrier for incorporating sulfur into semiconductor materials via laser processes without significant negative effects on the semiconductor materials. Additionally, it is noted that the dopant can also be a liquid solution of n-type or p-type dopant material dissolved in a solution such as water, alcohol, or an acidic or basic solution. The dopant can also be a solid material applied as a dried powder or suspension onto the wafer.

Semiconductor substrates can be annealed for a variety of reasons, including dopant activation, damage repair of semiconductor materials, and the like. In those aspects involving laser textured regions, the semiconductor material can be annealed prior to laser treatment, after laser treatment, during laser treatment, or both before and after laser treatment. Annealing can improve the semiconductor properties of the device, including increasing the photoresponsive properties of the semiconductor material. Additionally, annealing can reduce damage caused by the lasing process. Although any known annealing may be useful and is considered within this scope, annealing at lower temperatures may be particularly useful. Such "cold" annealing can significantly enhance the photoconductive gain and external quantum efficiency of devices utilizing such materials. In one aspect, for example, the semiconductor material can be annealed to a temperature of about 300°C to about 1100°C. In another aspect, the semiconductor material can be annealed to a temperature of about 500°C to about 900°C. In yet another aspect, the semiconductor material can be annealed to a temperature of about 700°C to about 800°C. In a further aspect, the semiconductor material can be annealed to a temperature of about 850°C or less.

The duration of the annealing procedure can vary according to the specific type of annealing being performed, as well as according to the materials used. For example, a fast annealing process can be used and therefore the duration of annealing may be shorter compared to other techniques. A variety of rapid thermal annealing techniques are well known, all of which should be considered within the scope of this invention. In one aspect, the semiconductor material can be annealed by a fast annealing process for a duration of about 1 μs or more. In another aspect, the duration of the fast annealing process can be about 1 μs to about 1 ms. As another example, a calcination or furnace annealing process can be used, which has a duration that can be longer compared to fast annealing. In one aspect, for example, the semiconductor material can be annealed by a firing annealing process for a duration of about 1 ms to several hours or more. As previously mentioned, when low oxygen content semiconductor materials are used, it may be beneficial to anneal such materials in a substantially oxygen-deficient environment.

As mentioned above, annealing can be useful in reducing defects inherent in the semiconductor substrate and, alternatively, in reducing electron/hole recombination. In other words, annealing can be useful in creating electronic states that effectively reduce unwanted recombination processes. Annealing the semiconductor material may also improve the responsivity or photoconductive gain of the device. Photoconductive elements can have dopants, impurities, or defects that can introduce energy levels that can trap carriers. Trapping carriers and reducing optical carrier recombination can lead to increasing the photoconductive gain of the device. The relationship between photoconductive gain and capture time can be expressed by equation (I).

Gain = "τL/τt" (I) where "τL" is the excess carrier lifetime and "τt" is the carrier transit time across the device. It should be appreciated that the lifetime of excess carrier can be extended by trapping the carrier species and reducing the rate of recombination. Increased gain can be achieved by trapping semiconductor centers with millisecond capture times at room temperature and short transition times in thin, lightly doped wafers. These trapping locations can improve or increase the photoconductive gain of the device by reducing carrier recombination and thus allowing more electrons to traverse to different regions without recombination.

Referring to FIG. 2, reflective layer 20 may be coupled to semiconductor substrate 12. Referring to FIG. A reflective layer can be coupled to any side or portion of the semiconductor substrate to reflect electromagnetic radiation back into the device. Thus, in one aspect, the reflective layer can be located on the semiconductor substrate on the opposite side of the incident electromagnetic radiation. Thus, as shown in FIG. 2, electromagnetic radiation passing through the semiconductor substrate and textured region 16 can be reflected back into the semiconductor substrate. Additionally, protective layer 22 can be coupled to the semiconductor substrate. Although the protective layer is shown coupled to the side of the semiconductor substrate facing the incident electromagnetic radiation, however, the protective layer can be located anywhere on the device and still be within the present scope.

As previously discussed, the location of the textured region can be used to provide enhancement and/or filtering of incident electromagnetic radiation. For example, textured regions located at the entry point of electromagnetic radiation into the photosensitive element tend to bend the electromagnetic radiation, particularly blue wavelengths. Thus, a level of tuning can be achieved by positioning a textured region on the surface adjacent to the incident electromagnetic radiation and intentionally causing filtering of blue wavelengths. Additionally, absorption of specific wavelengths of electromagnetic radiation occurs at different depths within the semiconductor layer and/or textured region. For example, by increasing absorption for green wavelengths, the resulting electrical signal for green wavelengths can be increased in diodes or pixels. A conventional 4-pixel image sensor has one red, one blue, and two green pixels, and it is believed that a larger number of green pixels improves the sensitivity of the human eye to green. Considering. Thus, in one aspect, a four-pixel image sensor can have one blue, one red, and one green pixel with enhanced green wavelength absorption. The fourth pixel can be used for IR or other wavelength selective pixel depending on the desired use of the imaging device.

FIG. 3 shows a photosensitive element having textured regions 30 located on both sides of semiconductor substrate 12. FIG. Such a configuration typically allows electromagnetic radiation exiting through both sides of the device to be further diffused and absorbed within the semiconductor substrate. A textured region can be located on one or more sides to facilitate improved absorption.

FIG. 4 shows a photosensitive element having a textured region 40 with a non-parallel surface to the semiconductor substrate 12. FIG. Therefore, the overall configuration of the textured region can be designed to further enhance absorption and/or optionally tune the element. As previously mentioned, non-parallel surfaces can have a variety of configurations, including, but not limited to, non-parallel slopes, pyramids, inverted pyramids, concave shapes, convex shapes, and the like. In some cases, the configuration of the textured region can function to direct or focus electromagnetic radiation into the semiconductor substrate; in other cases, the configuration of the textured region can serve to direct or focus electromagnetic radiation away from the semiconductor substrate. It can serve the function of directing or focusing radiation.

As shown in FIG. 5, the lens 50 can be coupled to the semiconductor substrate 12 on the side facing the incident electromagnetic radiation. The lens can therefore focus electromagnetic radiation into the semiconductor substrate. On those sides that have circuits or other structures placed on the incident electromagnetic radiation surface, the lens can further focus the light around such structures, thereby reducing optical scattering and noise. .

As shown in FIG. 6, a textured region 60 is located on the semiconductor substrate 12 adjacent to the plurality of doped regions 14,16. The textured region can be associated with at least one of the doped regions, as shown, or the textured region can also be distinguished from the doped region (not shown). Electromagnetic radiation may enter the photosensitive element on a side adjacent to the doped region, or alternatively, on an opposite side of the doped region.

7-11 illustrate various steps in manufacturing a photosensitive pixel according to aspects of the present disclosure. FIG. 7 shows a cross-section of a front-illuminated (FSI) photosensitive pixel element. The photosensitive pixel element may include a semiconductor substrate 72, which may be referred to as bulk semiconductor material. The semiconductor substrate includes at least one doped region 74 that can be doped with an electron-donating or hole-donating species to make the region more positive or negative polarity compared to the semiconductor substrate. In one aspect, for example, the doped region can be p-doped. In another aspect, the doped region can be n-doped. A heavily doped region 76 can be formed on or near the doped region to create a pin diode. In one example, the semiconductor substrate can be negative in polarity and the doped regions and heavily doped regions can be doped with p+ and n- dopants, respectively. In some aspects, the region n(--), n(-), n(+), n(++), p(--), p(-), p(+), or p(+ +) type doping variations can be used. Note that in one aspect, the heavily doped region can be a textured region. In other words, textured surface features can be formed on or in the heavily doped region.

The device of FIG. 7 may further include various metal regions 78, at least one via 80, a protective layer 82, trench isolation 84, and electrically conductive elements 86. Trench isolation elements can preserve pixel-to-pixel uniformity by reducing optical and electrical crosstalk. Trench isolation can be shallow (Figure 7) or deep (Figure 12) trench isolation. Trench isolation can include a variety of materials including, but not limited to, dielectric materials, reflective materials, conductive materials, light diffusing features, and the like. These trench isolation regions can be configured to reflect incident light until it is absorbed, thereby increasing the effective absorption length of the device.

As shown in FIG. 8, a carrier substrate or carrier wafer 88 can be coupled to the light sensing pixels. In one aspect, a carrier substrate can be placed on the protective layer 82, but the carrier substrate can be placed on any surface of the device. In one aspect, for example, the carrier substrate can be disposed on a semiconductor substrate (not shown). The carrier substrate can be coupled to the light sensing pixel by a variety of techniques, and any such coupling mechanism is within the scope of the present invention. In one aspect, for example, the coupling can be performed by a bonding or adhesive layer disposed on the element, for example on a protective layer. The support substrate can provide support to the semiconductor device both during and after manufacturing, depending on whether the support is removed. The carrier substrate can consist of the same or similar semiconductor material as the bulk semiconductor material, or it can also consist of a different material.

As shown in FIG. 9, textured region 90 is coupled to semiconductor substrate 72 on the opposite side of doped regions 74, 76. Therefore, light entering from the direction of the doped region passes through the semiconductor substrate before contacting the textured region. The textured regions can be disposed across the entire surface of the semiconductor substrate, as shown in FIG. 9, or can be disposed on one or more discrete regions (not shown).

As shown in FIG. 10, an additional carrier support substrate 100 can be coupled to the device on the opposite side of the carrier support substrate 88. Additional carrier support substrates can be utilized for various purposes, such as providing additional support to the device, facilitating removal of the first carrier support substrate, etc. A reflective layer 102 may be disposed between the textured region 90 and the carrier support substrate. Accordingly, the reflective layer can reflect electromagnetic radiation passing through the textured region back towards the semiconductor substrate 72, thus reducing optical losses and backscattering. Thus, in some aspects, the reflective layer can increase the quantum efficiency of the device. The reflective layer material can be any reflective material that can be incorporated into such devices. Non-limiting examples may include materials such as silver, aluminum, etc.

As shown in FIG. 11, the carrier support substrate can be removed to expose the protective layer 82 or any other material layer previously covered by the carrier support substrate. The additional carrier substrate 100 can be retained within the device, removed from the device, or thinned to reduce the thickness of the substrate, depending on the intended use of the device. Removal of material from the device, including the carrier support substrate and additional carrier substrates, is accomplished by a variety of methods including, but not limited to, etching, chemical mechanical polishing, ion implantation (i.e., smart cuts), etc. be able to.

Various types of trench isolation are envisioned and any such isolation is considered within the present scope. As previously discussed, trench isolation can be shallow (FIG. 7, 84) or deep (FIG. 12, 120) trench isolation. Trench isolation can also include shallow to deep depths depending on the device design. Trench isolation can include dielectric materials, reflective materials, conductive materials, and combinations thereof, including textured regions and other light diffusing features. Accordingly, the trench isolation layer may be configured to reflect incident electromagnetic radiation until it is absorbed, in some cases, thereby increasing the effective absorption length of the device. Additionally, in some aspects, pillar features can be incorporated into pixels by thinning or removing material from the semiconductor substrate using deep trench isolation and etching techniques. As shown in FIG. 13, textured region 130 can have a non-parallel surface with respect to semiconductor substrate 72, as described above. This non-parallel configuration, when included with deep trench isolation 120, can effectively focus electromagnetic radiation into the semiconductor substrate from multiple sides.

It is also envisioned that the non-bulk material can be formed or placed adjacent to the doped region within the device. The addition of non-bulk material allows electromagnetic radiation spreading features to be formed on or in the non-bulk material. In one aspect of the disclosure, a metal layer that defines the opening can also be included. A metal layer can be formed adjacent the doped region and defines an opening.<u style="Single">light incidence</u>territory<u style="Single">area</u>can have<u style="Single">This light incident</u>territory<u style="Single">The area is</u>It can also include anti-reflective materials.

FIG. 14 shows a photosensitive imaging device comprising two photosensitive pixels 140. Each photosensitive pixel includes a border region 142, which can include metal circuitry, and a textured region 144. Each photosensitive pixel may include at least one transistor 146 or other electrically conductive element. Additional readout and circuitry 148 can be utilized and shared by both photosensitive pixels.

Referring to FIG. 15, a backside illumination (BSI) photosensitive pixel is provided according to one aspect of the present disclosure. Lens 150 and anti-reflection coating 152 are placed on the back side of the pixel after thinning and trench isolation. A color filter 154 is optically coupled to the lens and allows for specific wavelength filtering of electromagnetic radiation. Textured region 156 may be coupled to semiconductor substrate 72 on the opposite side of the lens to provide diffuse scattering and reflection of incident electromagnetic radiation passing through the front side of the pixel. Therefore, electromagnetic radiation can be focused within the semiconductor substrate to the combined effects of the textured region and trench isolation 120.

FIG. 16 illustrates a front-illuminated (FSI) imager according to another aspect of the present disclosure. The anti-reflection protective layer on lenses 160 and 62 is coupled to the front side of the pixel. Textured region 90 and reflective layer 102 are coupled to semiconductor substrate 72 on the opposite side of the lens to provide diffuse scattering and reflection of incident electromagnetic radiation passing through the semiconductor substrate. Apertures 164 formed in the metal or other reflective material layer 166 can increase the effectiveness of the optical cavity. The lens thus focuses electromagnetic radiation through the aperture.

Other aspects of this disclosure contemplate various methods of making photosensitive diodes, pixels, and imaging devices. In one aspect, as shown in FIG. 17, a method of making a photosensitive imaging device includes forming a textured region on a semiconductor substrate having a plurality of doped regions forming at least one junction. 170, and textured regions are formed at locations that interact with electromagnetic radiation. The method also includes coupling 172 the electrically conductive element to the semiconductor substrate such that the electrically conductive element is operable to conduct an electrical signal from the at least one junction. In one aspect, a plurality of pixels can be associated together to form an imaging element. A protective layer can also be placed on the photosensitive imaging device to protect the device and/or reduce dark current.

In another aspect of the disclosure, a method of making a photosensitive diode is provided. Such a method includes the steps of forming at least one cathode and at least one anode on a surface of a semiconductor substrate, coupling a textured region to the semiconductor substrate, and coupling a support substrate to the semiconductor substrate. can include. The textured region can be located adjacent to the anode and cathode, opposite the anode and cathode, or both adjacent to and opposite the anode and cathode. An electrical conductor can be electrically coupled to at least one of an anode and a cathode to form a photosensitive pixel. In another aspect, the semiconductor substrate can be thinned to improve the response rate and/or speed of the device. A protective layer can also be placed on the photosensitive diode to protect the device and/or reduce dark current. Additional support substrates can be attached to the device to provide additional support. In one aspect, the additional support substrate can be located on the opposite side of the photosensitive diode from the support substrate. Subsequently, the support substrate can be removed to allow further processing.

Of course, it is to be understood that the above-described arrangements are merely illustrative of applications of the principles of the present disclosure. Numerous modifications and alternative arrangements may be devised by those skilled in the art without departing from the spirit and scope of this disclosure, and the appended claims are intended to cover such modifications and arrangements. . Accordingly, while the present disclosure has been described with specificity and detail in connection with what is presently considered the most practical embodiments of the disclosure, those skilled in the art will appreciate that the size, materials, shape, form, operation, etc. It will be apparent that numerous modifications may be made without departing from the principles and concepts described herein, including, but not limited to, variations in function and aspect, construction, and use. Will.