Image sensor with improved color accuracy

Abstract

The invention relates to an image sensor with improved color accuracy. An imaging device includes a plurality of optical sensors and a plurality of sets of interference filters disposed on an integrated circuit, where one of the plurality of sets of interference filters includes a plurality of interference filters constituting an array, where each interference filter is configured to allow light of a different wavelength range to pass through. The invention further comprises a plurality of groups of absorption optical filters, one group of absorption optical filters in the plurality of groups of absorption optical filters comprises a plurality of absorption optical filters forming a certain array, and each absorption optical filter is associated with one or more interference optical filters to form an absorption optical filter and interference optical filter pair. Each absorption filter and interference filter pair is associated with one or more optical sensors configured to allow passage of light having a narrower wavelength range than the individual absorption filter.

Description

[0001] This application is a divisional application of Chinese invention patent application filed on October 8, 2021, with application number 202111170589.6 and invention title "Image Sensor with Improved Color Accuracy". Technical Field

[0002] This invention generally relates to imaging, and more specifically to digital imaging with improved color accuracy. Background Technology

[0003] Most digital image sensors use color filters arranged on a grid of photoelectric sensors to reproduce a wide range of colors. For example, RGB color sensors use filters superimposed on the three main "channels" of red, green, and blue to represent the full spectrum. The filters used in RGB color sensors often include organic "absorbing" filters, which may have undesirable filtering properties. Filters with better filtering properties (such as interference filters) can be used; however, interference filters are more complex to manufacture, and light outside the passband can be adversely reflected, causing ghosting. Furthermore, while adding additional filters provides more channels and improves color accuracy, adding too many additional channels can reduce the resolution of the image sensor. Summary of the Invention

[0004] In one embodiment, an imaging apparatus is provided, comprising: a plurality of optical sensors disposed on an integrated circuit; a plurality of interference filters, wherein one of the plurality of interference filters comprises a plurality of interference filters forming an array, wherein each interference filter is configured to allow light of a different wavelength range to pass through; and a plurality of absorption filters, wherein one of the plurality of absorption filters comprises a plurality of absorption filters forming an array, wherein each absorption filter is associated with one or more interference filters to form an absorption filter and interference filter pair, wherein each absorption filter and interference filter pair is configured to allow light of a narrower wavelength range than a single absorption filter to pass through, wherein each absorption filter and interference filter is associated with one or more of the plurality of optical sensors. Attached Figure Description

[0005] Figure 1A An example of the passband response of an interference filter is shown; Figure 1B An example of the reflectivity response of an interference filter is shown; Figure 2A A side view of the image sensor system is provided, showing the characteristic reflectivity of the interference filter; Figure 2B An example of the response of a long-pass filter is shown; Figure 3A An example of the passband response of an RGB absorption filter is provided; Figure 3B A top view of an RGGB filter mosaic array conforming to the requirements of this invention is provided; Figure 4A The present invention provides characteristic passband responses of selected short-pass and long-pass interference filters that are covered on the selected absorption filter response, in accordance with the requirements of the present invention. Figure 4B A combined passband response of selected short-pass interference filters and long-pass interference filters with a matched RGB absorption filter, conforming to the requirements of this invention, is provided. Figure 5 A top view of an example of a 6-channel color filter array conforming to the requirements of this invention is provided; Figure 6 A side view of an image sensor with an absorption filter covering an interference filter, conforming to the requirements of this invention, is provided; Figure 7 A side view of an image sensor with microlenses covering absorption filters and interference filters, conforming to the requirements of this invention, is provided; Figure 8 It provides the characteristic passband response of a multi-band interference filter overlaid on each absorption filter in an RGB filter configuration.

[0006] Figure 9 Examples of spectral results for the combined passband response of characteristic RGB absorption filter and interference filter pairs that meet the requirements of this invention are provided; Figure 10 A side view of an image sensor with an absorption filter covering an interference filter, conforming to the requirements of this invention, is provided; Figure 11 A flowchart illustrating an example of a sensor manufacturing method conforming to the requirements of this invention. Detailed Implementation

[0007] In various embodiments, the digital image sensor combines an absorptive color filter with an interference filter to expand the available color channels, providing additional color channels. In other embodiments, the absorptive color filter and interference filter are combined to provide additional channels for ultraviolet (UV), near-infrared (NIR), and infrared (IR) wavelengths. In some embodiments, the interference filter and absorptive filter are arranged in a stack above the photoelectric sensor array. In other embodiments, one or more interference filter passbands are selected and used in conjunction with individual absorptive filters to provide additional color banding for each pixel of the image sensor. In other example embodiments, multiple absorptive filters are selected to reduce ghosting artifacts in the sensor system.

[0008] Figure 1AAn example of the passband response of an interference filter is shown. In this example, the peak transmittance of the interference filter is centered on the target wavelength within the passband, which is the range of wavelengths that can pass through the interference filter. In this example, light in the passband passes through the interference filter and reaches the pixel. Light with wavelengths outside the range that can pass through the interference filter is reflected at the interference filter. Figure 1B Showing Figure 1B An example of the reflectivity of an interference filter is shown. In this example, the interference filter acts as a mirror for light outside the passband.

[0009] Figure 2A A side view of the image sensor system 10 is provided, showing the characteristic reflectivity of an interference filter. In this example, incident light received by the sensor system passes through one or more lens elements 44, which pass through the passband of an interference filter (such as interference filters 42A-42F), reach a pixel element (such as pixel element 52), and / or are reflected back as reflected light 62. Other elements of the image sensor system (such as a housing glass 40) can reflect this reflected light again, passing through the passband of another interference filter. In one example, the sensor system 10 may include additional elements such as the housing glass 40 of the image sensor, lens elements 44, encapsulation boundaries, or bonding lines (not shown), each of which can reflect light reflected by the interference filter outside the passband of the interference filter. For example, the image sensor 10 may employ a metal, plastic, glass, or ceramic housing (not shown), any of which can reflect unwanted light back. Multiple reflections or "bouncing" of light in the image sensor system 10 can produce ghosting and / or blur the image sensor because the reflected light will be canceled out by the incident light received at the interference filter. In one example, one or more band-stop filters may be disposed on the top surface of the protective glass 40 or on the top surface of the interference filters 42A–42F.

[0010] Typical absorptive color filters in RGB (or RGGB) image sensors (such as red-green-blue (RGB) filters) absorb light outside the passband of a given filter, thus minimizing reflections. Therefore, absorptive filters rarely exhibit ghosting. However, absorptive filters are composed of materials such as colored organic photoresists (e.g., crosslinkable acrylic polymers containing photoinitiators), whose filtering properties are not ideal. On the other hand, compared to absorptive filters, interference filters offer useful filtering characteristics in addition to providing flexible filter response designs. However, besides ghosting, the manufacturing process of interference filters is relatively complex and may result in thick layers (pixels) on the photoelectric sensor.

[0011] Besides RGB (red, green, blue) filters, other image sensor configurations in RGB (or RGGB) based image sensors use absorption filters, each exhibiting similar performance issues. Examples include: cyan, magenta, and yellow filters in CMY imagers; red, green, blue, and white filters in RGBW imagers; and cyan, yellow, green, and magenta filters in CYGM imagers, etc.

[0012] Figure 2B An example of the response of an interference long-pass filter is shown. Interference filter arrays used to provide a wider spectral response require additional manufacturing layers to suppress unwanted out-of-band light. Figure 2B In the response example, long-pass response of light with wavelengths exceeding approximately 700 nm should also exhibit multiple harmonics and other undesirable transmission anomalies below approximately 500 nm, all of which require additional filter layers for removal. Therefore, a given interference filter for an image sensor may include a thick filter layer, which, when implemented as a pixelated array on the sensor, can introduce undesirable crosstalk between filter elements. Furthermore, the thick filter layers required to provide a broad spectral response for interference filters can increase substrate stress during manufacturing, complicating the fabrication process for small-outline pixels in high-resolution imagers. For example, during manufacturing, a thick filter layer may increase stress on one side of the semiconductor wafer, causing "wafer bending," leading to tooling problems and other issues.

[0013] Figure 3A Examples of passband responses for each red-green-blue (RGB) absorption filter are provided. RGB filters are typically implemented by repeatedly arranging three or four filters in an array on a grid or array of photoelectric sensor elements or pixels. When four filters are used in the array, the green filter is typically repeated, resulting in an RGGB filter array. Figure 3B A top view of a repeating RGGB filter array is provided, wherein filter 22A is a green filter, and filters 22B and 22C are a red filter and a blue filter, respectively.

[0014] Figure 4A Characteristic passband responses 72 and 74 of the selected short-pass and long-pass interference filters are provided, covering the selected absorption filter response 76. In this example, the first interference filter is configured to allow wavelength 72 to pass through when the desired wavelength is below the peak absorption wavelength of the selected absorption filter response. The second interference filter is configured to allow wavelength 74 to pass through when the desired wavelength is above the peak absorption wavelength of the selected absorption filter response 76. In one example, the first and second interference filters are combined with a matched absorption filter to produce two transmission peaks in the absorption filter, one slightly below the transmission peak of the absorption filter and one slightly above the transmission peak of the absorption filter.

[0015] In one example, the matched absorption filter absorbs out-of-band wavelengths from both the first and second interference filters, thus preventing these out-of-band wavelengths from being reflected back and creating ghosting. Furthermore, since no additional filter layer is needed to compensate for unfavorable transmission wavelengths, the filter stack complexity of the first and second interference filters can be reduced. In one example, Figure 4A As shown, reducing the number of filter layers reduces the thickness and complexity of the filter stack, thereby reducing filter costs and optical crosstalk.

[0016] Figure 4B The combined passband response of the selected short-pass and long-pass interference filters with a matched RGB absorption filter is shown. In one example, based on a reference... Figure 4A The explanation is that when each RGB (red, green, blue) absorption filter is used in combination with two matched interference filters, two transmission peaks appear as shown in the figure. In one example, these two transmission peaks may cause each filter mosaic to generate three additional color channels, for a total of six color channels: b'λ, bλ (blue), g'λ, gλ (green), r'λ, and rλ (red). In other examples, different filter configurations can be used to add additional channels to RGB filters and other filter configurations, including but not limited to cyan, magenta, and yellow (CMY) filters, red, green, blue, and white (RGBW) filters, and cyan, yellow, green, and magenta (CYGM) filters.

[0017] Figure 5 A top view of an example 6-channel color filter array is provided. In this example, each red, green, and blue filter in a typical RGGB filter array includes an additional filter response. In the example shown, the filter array includes filters b'λ, bλ (blue), g'λ, gλ (green), r'λ, and rλ (red). Other examples (not shown) include absorption filters matched with interference filters, providing additional channels for ultraviolet (UV), visible (VIS), near-infrared (NIR), and infrared (IR) wavelengths. In one example, an absorption filter (such as an organic filter) may be matched with a selected interference filter to provide additional channels in the UV, VIS, NIR, and IR bands. In another example, the interference filter may be a Fabry-Perot filter and / or a plasma interference filter. In yet another example, Figure 4B and Figure 5 The absorption filter and / or interference filter mentioned herein may include one or more short-pass filters, long-pass filters, band-pass filters or band-stop filters.

[0018] In a specific implementation and operational example, an image sensor (such as...) can be used... Figure 2AThe output of the image sensor 10 is processed to apply a specific filter array (such as...) Figure 5 The image generated during the processing of the 6-channel filter array example described above is subjected to a demosaic operation. In one example, a demosaic process can be employed to extract the spectral bandpass response from a set of filters. The demosaic process can be performed using one or more processors that use an algorithm or digital imaging procedure to reconstruct the bandpass response of the optical sensor associated with a single filter in the set of filters. In one example, if two sets of optical sensors are scattered, a demosaic process can be used to retrieve spectral information from a subset of filters in the scattered group or array.

[0019] In a specific relevant example, an optimized color filter configuration can be used to improve the demosaic algorithm. In another specific example, a multi-channel filter array can be appropriately configured so that each channel is separated from the nearest wavelength channel as much as possible, thereby preventing interference from adjacent filters from propagating to other channels in the filter array.

[0020] In another example, an image sensor example (such as...) Figure 2A The image sensor 10 in the image is processed in whole or in part to perform spectral correction and / or provide white balance correction on the image and / or discrete portions of the image generated by the image sensor. In another example, an optimized color filter configuration may be used to enhance the spectral correction of a white balance-specific algorithm.

[0021] Figure 6 Image sensors (such as) that provide absorption filters 64A, 64B, 66A, 66B, 68A, and 68B covering interference filters 42A-42F are available. Figure 2A A side view of the image sensor 10. In one example, each absorption filter 64A, 64B, 66A, 66B, 68A, and 68B is matched with one interference filter in a filter pair. In this example, absorption filters 64A and 64B are configured to allow wavelengths with the same center wavelength as the red absorption filter in a typical red-green-green-blue (RGGB) filter array to pass through. In one example, each absorption filter 64A, 64B, 66A, 66B, 68A, and 68B is matched with a different interference filter, combining the filter responses of the filter pair to produce two color channels that can be sensed by sensor 62. In one example, although illustrated as separate filters, absorption filters 64A and 64B could be made into a single filter. In another example, an interference filter could be added below two different absorption filters 64A and 64B to allow different portions of the interference band to pass through.

[0022] Figure 7A side view of an image sensor with microlenses covering absorption and interference filters is provided, employing the arrangement shown in Figures 4-6. In one example, microlens 90 may be positioned above one or more absorption filters 64A, 64B, 66A, 66B, 68A, and 68B, and above the pair of interference filters containing interference filters 42A-42F. In another example (not shown), a light-blocking plate or hood is used instead. Figure 7 The microlens 90, or additional light-blocking plates or shields, can be added to prevent stray light from affecting sensor performance. Examples of light-blocking plates or shields include one or more metals, a pseudo-metal, an opaque deposited material, and / or any other light-absorbing material. In other examples, light guides and / or deep trench isolation (DTI) techniques can be used to guide light and prevent crosstalk from degrading system performance. In another example, the absorption and interference filters in Figures 4-7 can be implemented in a back-illuminated sensor (BSI or BI). BSI-based imagers can use imaging elements arranged on the back of an integrated circuit containing an image sensor. In another example, planarization layers (such as organic spin-coated materials), oxide deposited layers, and other planarization layers can be used to compensate for the non-planarity of the filter layers.

[0023] In one implementation and operational example, the imaging apparatus includes multiple optical sensors disposed on an integrated circuit and multiple sets of interference filters arranged on top of the optical sensors. In one example, the multiple sets of interference filters are separated from the multiple optical sensors by etching a stop layer. In an alternative example, the multiple sets of interference filters are also separated from the multiple optical sensors by an air gap or a substantially transparent material. In one example, such material includes one or more organic materials. In another example, such material may be optimized to limit reflection and / or may include an alloy gradient or layer stack. In one example, one set of interference filters in the multiple sets of interference filters includes multiple interference filters constituting an array, wherein each interference filter is configured to allow light of a different wavelength range to pass through. In a particular example, each interference filter is one or more short-pass filters, long-pass filters, band-pass filters, or band-stop filters, and each interference filter is configured to allow light of at least one of the ultraviolet spectral range, visible spectral range, near-infrared spectral range, and infrared spectral range to pass through. In another particular example, one or more interference filters in the multiple sets of interference filters include a Fabry-Perot filter. In another specific example, one or more of the multiple sets of interference filters include a plasma interference filter. In another specific example, some of the multiple sets of absorption filters are configured to allow infrared light to pass through or to block infrared light. Filter examples include IR bandpass filters and IR cutoff filters, respectively. In yet another specific example, only one or a set of interference filters may be arranged at certain locations within the image sensor array, with some pixels associated with one or more absorption filters, and no underlying interference filter.

[0024] In one example, multiple sets of absorption filters are arranged on top of multiple sets of interference filters. Each absorption filter is one or more short-pass, long-pass, band-pass, or band-stop filters. Each interference filter is configured to allow light from at least one of the ultraviolet, visible, near-infrared, and infrared spectral ranges to pass through. The absorption filters may include organic filters and / or plasma filters. In one example, the multiple sets of absorption filters are separated from the multiple interference filters by etching a stop layer. In an alternative example, the multiple sets of absorption filters are also separated from the multiple interference filters by an air gap or a substantially transparent material. In one example, the transparent material may also be optimized to limit reflection and / or may include an alloy gradient and / or a stack of layers.

[0025] In one particular example, one set of absorption filters, comprising an array of absorption filters, includes each absorption filter in the set associated with one or more interference filters, forming an absorption filter and interference filter pair. In another particular example, at least one absorption filter and interference filter pair includes multiple interference filters. In one example, the response of each absorption filter and interference filter pair is configured to allow light with a narrower wavelength range than a single absorption filter to pass through. In another example, each absorption filter and interference filter pair is optically aligned with at least one of a plurality of optical sensors. In one example, a microlens assembly may include absorption filter and interference filter pairs, each arranged remotely from the respective optical sensors in the image sensor plane, such that light passing through a specific principal ray associated with a microlens passes sufficiently through the associated absorption filter and interference filter, respectively. In one example, microlens 90 may reduce crosstalk when matched with an absorption filter and interference filter pair.

[0026] In another example, the imaging device includes a plurality of microlenses arranged on top of multiple sets of absorption filters, each microlens being associated with at least one absorption filter. In yet another example, one or more light-blocking plates, light guides, and / or deep trench isolation techniques are employed to reduce the influence of stray light on one or more absorption and interference effects on the mid-light.

[0027] In one implementation and operational example, compared to image sensors and image sensor systems that use absorption filters alone, in addition to improved color accuracy, reference... Figure 4A , Figure 4B , Figure 5 and Figure 6 The additional color channels described can also be used to improve white balance. In a particular related example, a first image sensor with improved spectral resolution is configured to operate simultaneously with a second image sensor in an imaging system, the second image sensor being configured to image the same scene. In this example, the first image sensor provides information to improve color accuracy to correct the image from the second image sensor. In a related example, the second image sensor can improve spatial resolution while reducing spectral information compared to the first image sensor.

[0028] In a relevant implementation and operational example, an image sensor may be configured to include some absorption filters not paired with an interference filter, and other absorption filters paired with the interference filter. In a particular example, the green absorption filter G of the image sensor is not configured with an underlying paired interference filter, while another absorption filter Ga is configured with an underlying paired interference filter. In this example, the missing spectral filter response can be calculated as Gb = G – Ga. An implementation of paired and unpaired interference filters (such as...) Figure 4A , Figure 4B , Figure 5 and Figure 6 An image sensor with the filter shown can provide good performance in low-light conditions. The filter G in the relationship Gb = G – Ga will provide a wider optical bandwidth, thus being more sensitive in low-light conditions including one or more additional color channels. In a specific implementation and operational example, a filter without an underlying absorption filter is configured for use in low-light conditions. In another specific related example, interference filters sparsely distributed across the sensor array can be used to improve color accuracy while limiting the overall impact of additional color channels on photosensitivity. In a related implementation and operational example, the image sensor is configured to include some interference filters not paired with the absorption filter, as well as other interference filters paired with the absorption filter.

[0029] In another implementation and operational example, one or more cavity layers in any interference filter 42A–42F may be composed of a material or composite material that absorbs at least some unwanted wavelengths while allowing desired wavelengths to pass through. In one example, the material may comprise a porous optical material with a refractive index close to 1.0 (low-n material) and / or a high-refractive-index optical material. In one example, the cavity material may have a refractive index of 2.5. Semiconductors with a wavelength of 3.5 nm exhibit light propagation differently than cavities containing air (n = 1.0). In a particular example, the cavity may comprise an amorphous or semi-crystalline direct bandgap III-V material, wherein the absorption characteristics of the cavity material can be altered by changing the alloying ratio of the III-V material or by replacing different alloys. In one example, the cavity material may absorb photons with energies above the bandgap while allowing lower-energy photons to pass through.

[0030] Figure 8The characteristic passband response of a multi-band interference filter overlaid on each absorption filter in an RGB filter configuration is shown. In one implementation and operational example, the interference filter is configured as a multi-band filter, and when the interference filter is combined with an absorption filter, one spectral band of the multi-band filter can be selected to define a small portion of the absorption filter. In one example, fewer interference filters are required when manufacturing an image sensor, thus reducing complexity. (See reference...) Figure 8 The first interference filter is configured to provide a wavelength response of 140A within a narrow band below the peak absorption wavelength of each red, green, and blue absorption filter. In one implementation example, the second interference filter is configured to provide a wavelength response of 140B within a narrow band above the peak absorption wavelength of each absorption filter associated with response peaks 164A (blue), 164B (green), and 164C (red). In one example, the first and second multi-band interference filters are combined with a matched absorption filter to produce two transmission peaks for each absorption filter, one slightly below and one slightly above the transmission peak of the absorption filter. In one implementation example, a supplementary interference filter is configured to allow wavelengths within the narrow bands of each blue and green filter to pass through in a similar manner. In a related example, Figure 8 One embodiment is shown where one or more absorption filters can be selected for the target harmonics of the selected interference filter. In another example, only one interference filter or a set of interference filters can be arranged at specific locations in an image sensor array, such that the image sensor array includes both unmodified and modified RGB or RGGB filter structures, wherein the responses of the unmodified and modified RGB or RGGB filter structures can be used to calculate compensated RGB values.

[0031] In one example, a matched absorption filter (such as the absorption filter associated with response peaks 164A, 164B, and 164C) absorbs the out-of-band wavelengths of each of the first and second interference filters, thus preventing the out-of-band wavelengths from being reflected back and causing ghosting. In one example, because the unfavorable transmission wavelengths are significantly reduced, additional filter layers are no longer needed to compensate for them, potentially reducing the filter stack complexity of the first and second interference filters. In another example, this reduction in filter layers reduces the filter stack thickness and / or complexity, thereby reducing filter costs and crosstalk.

[0032] Figure 9 An example of spectral results for a combined passband response using characteristic RGB absorption and interference filter pairs is provided. In this example, a 6-filter array yields spectral results with double the number of color channels. Figure 9In a specific example, one absorption filter and interference filter pair provides two color channel responses 364A and 364B related to the blue channel, while another absorption filter and interference filter pair provides two color channel responses 366A and 366B related to the green channel, and a third absorption filter and interference filter pair provides two color channel responses 366A and 366B related to the green channel.

[0033] In one implementation example, an RGB-IR sensor can be formed using an interference infrared (IR) cutoff filter paired with R, G, and B absorption filters on an optical sensor array. In another example, the optical sensor is not covered by an IR cutoff filter and is configured to allow IR light to pass through. In yet another example, the optical sensor is covered by an absorbing IR bandpass filter (such as an IR bandpass filter), forming an IR optical sensor. In yet another example, the relevant optical sensor is not covered by a filter and allows all wavelengths to pass through, forming a substantially white optical sensor. In yet another example, the optical sensor is covered by an interference filter configured to allow selected wavelengths to pass through. In yet another example, the optical sensor is covered by both an interference filter and an absorption filter. In yet another example, the filters utilize a Bayer mosaic array, forming an RGB-IR sensor. In yet another example, a reference... Figure 9 Any of the examples described form an RGB-UV sensor (instead of an RGB-IR sensor or an additional one).

[0034] In one implementation and operational example, several Fabry-Perot filters can be arranged in an array on an image sensor, enabling different optical sensors within the image sensor to be paired with different Fabry-Perot passband filters. In one example, the filters are formed as a Bayer mosaic array on the sensor. In this example, multiple Fabry-Perot filters may belong to a predefined filter group, each filter group being formed using common mirror layers and alternative cavities. In one example, the cavity thickness of the Fabry-Perot filters in this group will determine the center wavelength of the Fabry-Perot filters. In one example, the mirror layer can be implemented using a reflective material and / or a Bragg stack. In another example, the cavities can be arranged in an array (e.g., through a stripping or etching process) instead of the thickness covering different optical sensors, such that each filter group contains Fabry-Perot filters with different cavity thicknesses, wherein each Fabry-Perot filter is substantially matched to at least one optical sensor. In one example, several optical sensors are adjusted to collect a portion of the incident wavelength, depending on a specific Fabry-Perot filter on the optical sensor.

[0035] In another implementation and operational example, multiple sets of Fabry-Perot filters can be produced, each filter set comprising at least one Fabry-Perot filter with a predetermined cavity thickness. In one example, when the spectral transmission of the Fabry-Perot filters outside the 500-600 nm wavelength range is rendered useless due to Bragg mirror leakage or due to multiple harmonics of the Fabry-Perot filters, a first filter set implements a group of four Fabry-Perot filters in the 500-600 nm range. In one example, when the spectral transmission of the Fabry-Perot filters outside the 600-700 nm wavelength range is rendered useless, a second filter set is configured to implement another group of four Fabry-Perot filters in the 600-700 nm range. In a particular example, the first set of filters is paired with one or more absorber filters configured to attenuate wavelengths outside the 500-600 nm passband. In this example, the absorption filter serves as a bandstop filter for the first set of Fabry-Perot filters. In another example, a second set of filters is paired with an absorption filter that attenuates wavelengths outside the 600-700 nm passband. In this example, one or more absorption filters may serve as bandstop filters for the second set of Fabry-Perot filters. In a related example, three or more sets paired with absorption filters can manage wavelength responses in both the visible and infrared spectra.

[0036] Figure 10 A side view of an image sensor 62 is provided, showing absorption filters 264A and 264B covering interference filter groups 242A and 242B. (Refer to...) Figure 6 , Figure 10 It can be considered as having an additional layer Figure 6 Such additional layers provide space for the fabrication of sensor systems. In one example, a stop layer 280 is deposited on the pixel layer of sensor 62 to prevent the pixel layer from being affected by subsequent photolithography processes. In one example, interference filter groups 242A and 242B are formed on the first stop layer, and a second stop layer is deposited on top of the interference filter groups 242A and 242B to prevent the interference filter groups 242A and 242B from being affected by subsequent fabrication processes. In one example, the fabrication of interference filters may result in non-uniform morphologies due to the different thicknesses of the filters. Therefore, one or more planarization layers can be provided to planarize the surface before forming the absorption filters.

[0037] In one implementation and operational example, one or more anti-reflective coatings or layers may be included between the functional elements of the image sensor. For example, stop layer 280 may include an anti-reflective coating. In one particular example, an anti-reflective coating may be applied to the pixel layer of image sensor 62; in another particular example, stop layer 280 includes an anti-reflective coating that may serve as a stop layer in subsequent photolithography steps. In another implementation and operational example, the anti-reflective coating or anti-reflective layer 282 may be located on top of absorption filters 264A and 264B. In one example, the anti-reflective coating may reduce light reflected from underlying structural elements such as the pixel layer or the surfaces of interference filter groups 242A and 242B.

[0038] In a relevant example, refer to Figure 6 and Figure 7 If necessary, anti-reflective coatings and / or materials can be added to reduce light reflected from any underlying structure. For example, this can be included on one or more top surfaces, bottom surfaces, or other surfaces of the absorbing filter. Figure 6 , Figure 7 or Figure 10 An anti-reflective coating is applied to the top surface of any sensor pixel layer to reduce light reflected from the underlying structure.

[0039] Figure 11 This is a flowchart illustrating an example of a sensor manufacturing method. The method begins at step 100, where a first set of thin film layers is deposited on a pre-fabricated semiconductor wafer substrate to provide the optical sensor (pixels) of an image sensor. In one implementation and operational example, prior to the deposition of the first set of thin film layers, a substrate (as shown in the reference) has been fabricated. Figure 10 The substrate mentioned may or may not have a passivation layer. In one example, the first set of thin film layers may begin at a first stop layer and / or end at a second stop layer. The method continues in step 102, wherein the first set of thin film layers is removed in areas where the first filter is not required. The first set of thin films may be removed first using a photolithography process, followed by dry and / or wet etching processes that stop at the stop layer or passivation layer.

[0040] The method continues in step 104, where a second set of thin film layers is deposited on the semiconductor wafer substrate, and then continues in step 106, where the second set of thin film layers is removed in areas where the second filter is not required. The second set of thin film layers can be removed first using a photolithography process, followed by dry and / or wet etching processes, which stop at a stop layer provided during the production of the first set of thin film layers. In step 108, the method repeats steps 104 to 106 as needed for additional filter layers. For example, if six different interference filters are required, step 108 would include repeating steps 104 to 106 (four times).

[0041] The method continues in step 110, where a planarization layer is added. This planarization is achieved by first using an oxide deposition step, followed by chemical mechanical planarization (CMP). Other planarization options include using spin coating (e.g., spin-coating glass) followed by etching of morphology peaks introduced during filter production, or selective etching of morphology peaks. In step 112, the method continues to coat the absorbing color filter layer. In one example, the absorbing color filter can be coated sequentially: using a spin-coated colored resist layer, then photocuring the resist in the areas where the filter is needed, and finally dissolving the uncured resist areas. For example, red-green-blue (RGB) filters can be applied in three separate photolithography processes, each using three different filters.

[0042] Please note that in all the embodiments described, one or more absorption filters may be replaced by plasma filters, which are typically implemented using arrayed metal layers to define the passband.

[0043] It should be noted that the terms that may be used in this article (such as bit stream, stream, signal sequence, etc. or their equivalents) are used interchangeably to describe data information whose content corresponds to the types of content described, such as data, video, language, text, graphics, audio, etc., any of which can generally be referred to as "data".

[0044] In this document, the terms “generally” and “approximately” provide industry-recognized tolerances for the correlation between their respective terms and / or parts. For some industries, the recognized tolerance is less than 1%, while for others it is 10% or greater. Other examples of industry-recognized tolerances range from less than 1% to 50%. Industry-recognized tolerances correspond to, but are not limited to, component values, integrated circuit process variations, temperature variations, rise and fall times, thermal noise, dimensions, signal errors, packet loss, temperature, pressure, material composition, and / or performance indicators. Within an industry, the variation in recognized tolerances may be greater than or less than a percentage level (e.g., dimensional tolerances less than + / - 1%). The correlation between parts may range from a difference of less than a percentage level to several percentage points. Other correlations between parts may range from differences of several percentage points to differences of various orders of magnitude.

[0045] Furthermore, in this document, the terms "configured," "operably coupled to," "coupled to," and / or "coupled" include direct coupling and / or indirect coupling via intermediate components (e.g., parts including, but not limited to, components, elements, circuits, and / or modules), wherein, for indirect coupling, the intermediate component does not modify signal information but may adjust its current level, voltage level, and / or power level. In this document, inferred coupling (i.e., based on inference, one component is coupled to another) includes direct and indirect coupling between two parts in the same manner as "coupled to."

[0046] In this document, the terms “configured,” “operable,” “coupled to,” or “operably coupled to” indicate that a part includes one or more power connections, inputs, or outputs that, when activated, can perform one or more of their respective functions, and further include inferred coupling to one or more other parts. In this document, the term “related to” includes a part that is directly and / or indirectly coupled to an independent part and / or embedded in another part.

[0047] In this document, the term "favorable comparison" indicates that a comparison between two or more parts, signals, etc., provides the desired relationship. For example, if the desired relationship is that signal 1 is of a greater magnitude than signal 2, a favorable comparison is achieved when signal 1 is of a greater magnitude than signal 2 or signal 2 is of a smaller magnitude than signal 1. Conversely, the term "unfavorable comparison" indicates that a comparison between two or more parts, signals, etc., fails to provide the desired relationship.

[0048] In this document, one or more claims may include the phrase "at least one of a, b, and c" (a specific form of this general form) or "at least one of a, b, or c" (this general form), wherein the elements may be more or less than "a," "b," and "c." In either wording, the phrase should be interpreted identically. In particular, "at least one of a, b, and c" is equivalent to "at least one of a, b, or c" and should refer to a, b, and / or c. For example, it should refer to: only "a," only "b," only "c," "a" and "b," "a" and "c," "b" and "c," and / or "a," "b," and "c."

[0049] Furthermore, in this document, the terms "processing module," "processing circuit," "processor," and / or "processing unit" may refer to one or more processing devices. Such processing devices may include microphones, microcontrollers, digital signal processors, microcomputers, central processing units, field-programmable gate arrays, programmable logic devices, state machines, logic circuits, analog circuits, digital circuits, and / or any device that manipulates signals (analog and / or digital) according to circuit hard-coded and / or operational instructions. The processing module, module, processing circuit, and / or processing unit may be or further include memory and / or integrated storage elements, which may be one storage device, multiple storage devices, and / or embedded circuitry of another processing module, module, processing circuit, and / or processing unit. Such storage devices may include read-only memory, random access memory, volatile memory, non-volatile memory, static memory, dynamic memory, flash memory, cache memory, and / or any device storing digital information. Please note that if the processing module, module, processing circuit, and / or processing unit comprises more than one processing device, the processing device may be centrally located (e.g., directly coupled together via a wired and / or wireless bus structure) or may be distributed (e.g., cloud computing indirectly coupled via a local area network and / or wide area network). It should be further noted that if the processing module, module, processing circuit, and / or processing unit implements one or more of its functions through state machines, analog circuits, digital circuits, and / or logic circuits, the memory and / or storage element storing the corresponding operation instructions may be embedded within or outside the circuitry composed of state machines, analog circuits, digital circuits, and / or logic circuits. It should also be noted that the storage element may store, and the processing module, module, processing circuit, and / or processing unit may execute hard-coded and / or operation instructions corresponding to at least one or more steps and / or functions shown in the figures. Such a storage device or storage element may be included in a single product.

[0050] The foregoing has described one or more embodiments by means of method steps illustrating the performance of specific functions and their relationships. For ease of description, the boundaries and sequences of these functional building blocks and method steps have been arbitrarily defined herein. Alternative boundaries and sequences can be defined as long as specific functions and relationships are properly performed. Therefore, any such alternative boundaries or sequences are within the scope and spirit of the claims. Furthermore, for ease of description, the boundaries of these functional building blocks have been arbitrarily defined. Alternative boundaries can be defined as long as certain important functions are properly performed. Similarly, flowchart blocks can also be arbitrarily defined to illustrate certain important functions.

[0051] In terms of usage, flowchart block boundaries and sequences can also be defined in other ways, while still performing certain important functions. Therefore, such alternative definitions of functional building blocks and flowchart blocks are all within the scope and spirit of the claims. Those skilled in the art will also recognize that the functional building blocks, as well as other illustrative blocks, modules, and components herein, can be implemented as illustrated or by discrete components, application of specific integrated circuits, processors executing appropriate software, or any combination thereof.

[0052] In addition, flowcharts may include "Start" and / or "Continue" instructions. "Start" and "Continue" instructions indicate that the steps shown can be incorporated into or used in conjunction with one or more other procedures. Furthermore, flowcharts may include "End" and / or "Continue" instructions. "End" and / or "Continue" instructions indicate that the steps shown can be concluded as illustrated, or incorporated into or used in conjunction with one or more other procedures. In this case, "Start" indicates that the first step shown begins, prior to which other activities not explicitly shown can be performed. Furthermore, "Continue" indicates that the steps shown can be performed multiple times, and / or after which other activities not explicitly shown can be performed. Moreover, although flowcharts indicate a specific order of steps, other orders can also be used as long as the principle of cause and effect is maintained.

[0053] In this document, the one or more embodiments are used to illustrate one or more aspects, features, concepts, and / or examples. A physical embodiment of an apparatus, product, machine, and / or process may include one or more aspects, features, concepts, examples, etc., described with reference to the one or more embodiments described herein. Furthermore, between the figures, the embodiments may include functions, steps, and modules with the same or similar names, which may use the same or different reference numerals; therefore, these functions, steps, and modules may be the same, similar, or different functions, steps, modules, etc.

[0054] Unless otherwise expressly stated to the contrary, in any of the figures shown herein, the signals entering and exiting elements and / or between elements may be analog or digital signals, continuous-time or discrete-time signals, and single-ended or differential signals. For example, if a signal path is shown as a single-ended path, it also represents a differential signal path. Similarly, if a signal path is shown as a differential path, it also represents a single-ended signal path. While one or more specific architectures are described herein, other architectures may be implemented, such as those using one or more data buses not explicitly stated, where elements can be directly connected, and / or indirectly coupled, as will be recognized by those skilled in the art.

[0055] The term "module" is used in the description of one or more embodiments. A module implements one or more functions through a device such as a processor or other processing device, or through a memory that may include a storage device for operation instructions, or other hardware that operates therewith. A module may operate independently and / or with software and / or firmware. In this document, a module may include one or more submodules, and each submodule may be one or more modules.

[0056] Furthermore, in this document, computer-readable storage includes one or more storage elements. A storage element can be a single storage device, multiple storage devices, or a set of storage locations within a storage device. Such storage devices include read-only memory, random access memory, volatile memory, non-volatile memory, static memory, dynamic memory, flash memory, cache memory, and / or any device for storing digital information. These storage devices include solid-state memory, hard disk storage, cloud storage, thumb drives, server storage, computing device storage, and / or other physical media used for storing digital information.

[0057] While specific combinations of functions and features of one or more embodiments have been explicitly described herein, other combinations of such functions and features may also be used. The invention is not limited to the specific examples disclosed herein, and such other combinations are expressly included.

Claims

1. An imaging device, comprising: Multiple optical sensors mounted on a single integrated circuit; Multiple sets of interference filters, wherein one set of interference filters comprises multiple interference filters forming an array, wherein each interference filter is configured to allow light of different wavelength ranges to pass through; and Multiple sets of absorption filters, wherein one set of absorption filters comprises multiple absorption filters forming an array, wherein each absorption filter is associated with one or more interference filters to form an absorption filter and interference filter pair, wherein each absorption filter and interference filter pair is configured to allow light with a narrower wavelength range than a single absorption filter to pass through, and wherein each absorption filter and interference filter is associated with one or more optical sensors among a plurality of optical sensors.

2. The imaging device according to claim 1, wherein, Multiple sets of interference filters are separated from multiple optical sensors by etching a stop layer.

3. The imaging device according to claim 1, wherein, Multiple sets of interference filters are separated from multiple optical sensors through an air gap or a substantially transparent material.

4. The imaging device according to claim 3, wherein, The basic transparent material includes one or more organic materials.

5. The imaging device according to claim 3, wherein, The transparent material is optimized to limit reflection and / or may include an alloy gradient or layer stack.

6. The imaging apparatus according to claim 1, wherein, Each interference filter is selected from a group of filters including a short-pass filter, a long-pass filter, a band-pass filter, or a band-stop filter, wherein each interference filter is configured to allow light from at least one of the ultraviolet, visible, near-infrared, and infrared spectral ranges to pass through.

7. The imaging apparatus according to claim 1, wherein, One or more of the multiple sets of interference filters include a Fabry-Perot filter.

8. The imaging apparatus according to claim 1, wherein, At least some of the multiple sets of absorption filters are configured to block light in the infrared wavelength range.

9. The imaging apparatus according to claim 1, wherein, Some of the multiple absorption filters include at least one organic filter or plasma filter.

10. The imaging apparatus according to claim 1, wherein, Multiple absorption filters are separated from multiple interference filters by etching a stop layer.

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