Sensor device comprising one or more metal-dielectric filters

Abstract

The present application relates to a sensor device comprising one or more metal-dielectric optical filters. The invention provides a sensor device comprising one or more sensor elements and one or more optical filters. Each of the one or more optical filters comprises a plurality of dielectric layers and a plurality of metal layers alternately stacked. The metal layers are inherently protected by the dielectric layers. In particular, the metal layers have tapered edges which are protectively covered by one or more dielectric layers.

Description

[0001] This application is a divisional application of the application filed on December 19, 2013, with application number 201310704361.X and invention title "Sensor Device Including One or More Metal-Dielectric Filters". Technical Field

[0002] The present invention relates to sensor devices comprising one or more filters, and more specifically, to one or more metal-dielectric filters. Background Technology

[0003] An image sensor is a sensor device used in imaging devices (such as cameras, scanners, and copiers) to convert light signals into electrical signals to allow image capture. An image sensor typically includes multiple sensor elements and multiple filters arranged on these sensor elements. A color image sensor includes multiple color filters arranged in an array (i.e., a color filter array (CFA)). A CFA includes different types of color filters with different color passbands, such as red, green, and blue (RGB) filters.

[0004] Conventionally, absorption filters formed using dyes are used as color filters. Unfortunately, such dye-based color filters have relatively wide color bands, resulting in less vibrant colors. Alternatively, dichroic filters (i.e., interference filters) formed from stacked dielectric layers can be used as color filters. Such all-dielectric color filters have higher transmittance levels and narrower color bands, resulting in brighter and more vibrant colors. However, the color band of all-dielectric color filters experiences a relatively large center wavelength shift with changes in the angle of incidence, leading to an undesirable shift in color.

[0005] Furthermore, all-dielectric color filters typically consist of a large number of stacked dielectric layers and are relatively thick. Therefore, all-dielectric color filters are expensive and difficult to manufacture. In particular, all-dielectric color filters are difficult to etch using chemical methods. Therefore, stripping processes are preferred for patterning. Examples of stripping processes for patterned all-dielectric CFAs are disclosed in U.S. Patent No. 5,120,622 to Hanrahan, issued June 9, 1992; U.S. Patent No. 5,711,889 to Buchsbaum, issued January 27, 1998; U.S. Patent No. 6,238,583 to Edlinger et al., issued May 29, 2001; U.S. Patent No. 6,638,668 to Buchsbaum et al., issued October 28, 2003; and U.S. Patent No. 7,648,808 to Buchsbaum et al., issued January 19, 2010, all of which are incorporated herein by reference. However, stripping processes are generally limited to a filter spacing approximately twice the filter height, making it difficult to implement all-dielectric CFAs suitable for smaller color image sensors.

[0006] In addition to transmitting visible light in the color passband, dye-based color filters and all-dielectric color filters also transmit infrared (IR) light, which contributes to noise. Therefore, color image sensors generally also include IR blocking filters arranged on the CFA. Conventionally, absorption filters formed of colored glass or dichroic filters formed of stacked dielectric layers are used as IR blocking filters. Alternatively, induced transmission filters formed of stacked metal and dielectric layers can be used as IR blocking filters. Examples of metal-dielectric IR blocking filters are disclosed in U.S. Patent No. 5,648,653 to Sakamoto et al., issued July 15, 1997, and in U.S. Patent No. 7,133,197 to Ockenfuss et al., issued November 7, 2006, both of which are incorporated herein by reference.

[0007] To avoid the use of IR-blocking filters, induced transmission filters formed by stacked metal and dielectric layers can be used as color filters. Such metal-dielectric color filters are inherently IR-blocking. Generally, metal-dielectric color filters have relatively narrow color passbands, and their wavelengths do not shift significantly with changes in the angle of incidence. Furthermore, metal-dielectric color filters are typically much thinner than all-dielectric color filters. Metal-dielectric color filters are disclosed in U.S. Patent No. 4,979,803 to McGuckin et al., issued December 25, 1990; U.S. Patent No. 6,031,653 to Wang, issued February 29, 2000; U.S. Patent Application No. 2009 / 0302407 to Gidon et al., published December 10, 2009; U.S. Patent Application No. 2011 / 0204463 to Grand, published August 25, 2011; and U.S. Patent Application No. 2012 / 0085944 to Gidon et al., published April 12, 2012. These patents / patent applications are incorporated herein by reference.

[0008] Typically, the metal layer in a metal-dielectric color filter is a silver layer, which is unstable in the environment and deteriorates when exposed to even small amounts of water or sulfur. Etching the silver layer chemically exposes its edges to the environment, allowing it to deteriorate further. Therefore, in most cases, metal-dielectric color filters (CFAs) are patterned by adjusting only the thickness of the dielectric layer to select different color passes. In other words, different types of metal-dielectric color filters with different color passes require the same amount and thickness of silver layers. Unfortunately, these requirements severely limit the possible optical designs of metal-dielectric color filters. Summary of the Invention

[0009] This invention provides metal-dielectric optical filters that are not subject to these requirements, and are particularly suitable for use in image sensors and other sensor devices.

[0010] Therefore, this application also includes the following:

[0011] 1) The present invention relates to a sensor device comprising: one or more sensor elements; and one or more filters disposed on the one or more sensor elements, wherein each of the one or more filters comprises: a plurality of dielectric layers; and a plurality of metal layers stacked alternately with the plurality of dielectric layers, wherein each of the plurality of metal layers has a tapered edge at the periphery of the filter being protectively covered by one or more of the plurality of dielectric layers.

[0012] 2) The sensor device as described in 1), wherein the one or more filters are disposed directly on the one or more sensor elements.

[0013] 3) The sensor device as described in 2), wherein the one or more filters are formed on the one or more sensor elements by a stripping process.

[0014] 4) The sensor device as described in 1), wherein the one or more filters have a substantially flat top and sloping sides.

[0015] 5) The sensor device as described in 1), wherein each of the plurality of metal layers is substantially encapsulated by the two closest dielectric layers of the plurality of dielectric layers.

[0016] 6) The sensor device as described in 1), wherein each of the plurality of metal layers is composed of silver.

[0017] 7) The sensor device as described in 1), wherein each of the plurality of dielectric layers is composed of a high refractive index dielectric material having a refractive index greater than about 2.0 at 550 nm.

[0018] 8) The sensor device as described in 7), wherein the high refractive index dielectric material is ultraviolet-absorbing, and wherein each of the one or more filters has an average out-of-band transmittance of less than about 2% between about 300 nm and about 400 nm.

[0019] 9) The sensor device as described in 1), wherein each of the plurality of dielectric layers is composed of titanium dioxide, zirconium dioxide, niobium pentoxide, tantalum pentoxide, or a mixture thereof.

[0020] 10) The sensor device as described in 1), wherein each of the one or more filters further comprises a plurality of corrosion-inhibiting layers disposed between the plurality of dielectric layers and the plurality of metal layers.

[0021] 11) The sensor device as described in 10), wherein the dielectric layer D, the plurality of corrosion-inhibiting layers C, and the plurality of metal layers M are arranged in a manner of D (C / M / C / D). n The order of the stacked numbers is such that n ≥ 2.

[0022] 12) The sensor device as described in 10), wherein each of the plurality of corrosion inhibition layers is composed of ZnO.

[0023] 13) The sensor device as described in 1) further includes a dielectric coating that protectively covers the one or more filters.

[0024] 14) The sensor device as described in 1), wherein the one or more filters are one or more color filters, photosensitive filters, infrared blocking filters, or combinations thereof.

[0025] 15) The sensor device as described in 1), wherein the one or more sensor elements are composed of a plurality of sensor elements, and wherein the one or more filters are composed of a plurality of filters.

[0026] 16) The sensor device as described in 15), wherein one or more sensor elements are arranged in a two-dimensional array, and wherein the plurality of filters are arranged in a corresponding two-dimensional array.

[0027] 17) The sensor device as described in 15), wherein the plurality of filters are substantially separate from each other.

[0028] 18) The sensor device as described in 15), wherein the plurality of filters include filters of different types having different passbands.

[0029] 19) The sensor device as described in 18), wherein at least two of the different types of filters comprise different numbers of metal layers.

[0030] 20) The sensor device as described in 18), wherein at least two of the different types of filters have metal layer thicknesses that differ from each other. Attached Figure Description

[0031] The invention will be described in more detail with reference to the accompanying drawings, in which:

[0032] Figure 1A This is a schematic cross-sectional view of the first embodiment of the filter of the present invention;

[0033] Figures 1B to 1G Manufacturing process is shown Figure 1A The various steps in the method of making a filter;

[0034] Figure 2 This is a schematic cross-sectional view of a second embodiment of the filter of the present invention;

[0035] Figure 3 This is a schematic diagram of the cross-sections of multiple filters;

[0036] Figure 4A This is a table showing the number of layers, materials, and thickness of an exemplary red filter;

[0037] Figure 4B This is a table showing the number of layers, materials, and thickness of an exemplary green filter;

[0038] Figure 4CThis is a table showing the number of layers, materials, and thickness of an exemplary blue filter;

[0039] Figure 4D This is a table showing the number of layers, materials, and thickness of an exemplary photopic filter;

[0040] Figure 5A and 5B yes Figures 4A to 4C Transmission spectrum curves of exemplary red, green, and blue filters;

[0041] Figure 5C yes Figure 4D Transmission spectrum curves of an exemplary visible filter at incident angles from 0° to 60°;

[0042] Figure 6A yes Figures 4A to 4C Color gamut curves for exemplary red, green, and blue (RGB) filter groups and conventional dye-based RGB filter groups;

[0043] Figure 6B yes Figure 4A The color trajectory curves of an exemplary red filter and a conventional all-dielectric red filter at incident angles from 0° to 60°;

[0044] Figure 6C yes Figure 4D The curves of the color trajectory of an exemplary visible filter at incident angles from 0° to 60°;

[0045] Figure 7 This is a schematic cross-sectional view of a first embodiment of the sensor device of the present invention; and

[0046] Figure 8 This is a schematic cross-sectional view of a second embodiment of the sensor device of the present invention.

[0047] Detailed description of the invention

[0048] This invention provides a metal-dielectric filter with a protected metal layer, which is particularly suitable for use in sensor devices. The filter comprises multiple dielectric layers and multiple metal layers stacked alternately. The metal layers are intrinsically protected by the dielectric layers. In particular, the metal layers have tapered edges protectively covered by one or more dielectric layers. Therefore, the metal layers increase resistance to environmental degradation, resulting in a more durable filter.

[0049] In some embodiments, dielectric and metal layers are stacked without any intermediate layers. (Reference) Figure 1AA first embodiment of the filter 100 disposed on the substrate 110 includes three dielectric layers 120 and two metal layers 130 stacked alternately. Each metal layer 130 is disposed between and adjacent to the two dielectric layers 120, and is thus protected from environmental influences.

[0050] The metal layer 130 has a tapered edge 131 at the periphery 101 of the filter 100. In other words, the thickness of the metal layer 130 is substantially uniform throughout the central portion 102 of the filter 100, but gradually decreases at the periphery 101. Similarly, the dielectric layer 120 is substantially uniform in thickness throughout the central portion 102 of the filter 100, but gradually decreases at the periphery 101. Therefore, the central portion 102 of the filter 100 is substantially uniform in height, while the periphery 101 of the filter 100 is sloping. In other words, the filter 100 has a substantially flat top and sloping sides.

[0051] Advantageously, the tapered edge 131 of the metal layer 130 is not exposed to the environment. Instead, the tapered edge 131 of the metal layer 130 is covered by one or more dielectric layers 120. The one or more dielectric layers 120 inhibit environmental degradation (e.g., corrosion) of the metal layer 130, for example, by preventing sulfur and water from diffusing into the metal layer 130. Preferably, the metal layer 130 is substantially encapsulated by the dielectric layers 120. More preferably, the tapered edge of the metal layer 130 is protectively covered by adjacent dielectric layers 120, and the metal layer 130 is substantially encapsulated by adjacent dielectric layers 120.

[0052] refer to Figures 1B to 1G The first embodiment of filter 100 can be manufactured by a stripping process. See details. Figure 1B In the first step, substrate 110 is provided. See details... Figure 1C In the second step, a photoresist layer 140 is applied to the substrate 110. Generally, the photoresist layer 140 is applied by spin coating or spray coating.

[0053] For details, please refer to the following: Figure 1D In the third step, the photoresist layer 140 is patterned to expose the area of ​​the substrate 110 where the filter 100 will be disposed, i.e., the filter area. The other areas of the substrate 110 remain covered by the patterned photoresist layer 140. Generally, the photoresist layer 140 is patterned by first exposing the area of ​​the photoresist layer 140 covering the filter area of ​​the substrate 110 to ultraviolet (UV) light using a mask, and then developing (i.e., etching) the exposed area of ​​the photoresist layer 140 using a suitable developer or solvent.

[0054] The photoresist layer 140 is patterned such that overhangs 141 (i.e., undercuts) are formed around the patterned photoresist layer 140 surrounding the filter region. Generally, the overhangs 141 are formed by chemically modifying the top of the photoresist layer 140, for example, using a suitable solvent, such that the top develops more slowly than the bottom of the photoresist layer 140. Alternatively, the overhangs 141 can be formed by applying a double-layer photoresist layer 140 to the substrate 110, the double-layer photoresist layer 140 consisting of a top layer that develops more slowly and a bottom layer that develops more quickly.

[0055] For details, please refer to the following: Figure 1E In the fourth step, a multilayer stack 103 is deposited on the patterned photoresist layer 140 and the filter region of the substrate 110. A portion of the multilayer stack 103 disposed on the filter region of the substrate 110 forms the filter 100. Layers of the multilayer stack 103 corresponding to the layers of the filter 100 can be deposited using various deposition techniques, such as: evaporation (e.g., thermal evaporation, electron beam evaporation, plasma-assisted evaporation, or reactive ion evaporation); sputtering (e.g., magnetron sputtering, reactive sputtering, alternating current (AC) sputtering, direct current (DC) sputtering, pulsed DC sputtering, or ion beam sputtering); chemical vapor deposition (e.g., plasma-enhanced chemical vapor deposition); and atomic layer deposition. Furthermore, different layers can be deposited using different deposition techniques. For example, a metal layer 130 can be deposited by sputtering with a metal target, and a dielectric layer 120 can be deposited by reactive sputtering with a metal target in the presence of oxygen.

[0056] Because the protrusion 141 shields the periphery of the filter region of the substrate 110, the deposited layer gradually decreases in thickness towards the periphery 101 of the filter 100. When the dielectric layer 120 is deposited on the metal layer 130, the dielectric layer 120 not only covers the top surface of the metal layer 130, but also covers the tapered edge 131 of the metal layer 130, thereby protecting the metal layer 130 from environmental influences.

[0057] For details, please refer to the following: Figure 1F In the fifth step, a portion of the multilayer stack 103 on the patterned photoresist layer 140 is removed along with the photoresist layer 140, i.e., stripped. Generally, the photoresist layer 140 is stripped using a suitable stripping agent or solvent. The filter 100 remains on the filter region of the substrate 110. The substrate 110 may be, for example, a conventional sensor element.

[0058] It should be noted that Figures 1B to 1FThe stripping process can also be used to simultaneously form multiple filters 100 of the same type (i.e., with the same optical design) on substrate 110. Furthermore, the stripping process is repeatable so that one or more filters of different types (i.e., with different optical designs) can subsequently be formed on the same substrate 110. Therefore, a filter array can be formed on substrate 110. Substrate 110 can be, for example, a conventional sensor array.

[0059] refer to Figure 1G In an optional sixth step, an additional dielectric coating 150 is deposited on the filter 100. The dielectric coating 150 can be deposited using one of the previously mentioned deposition techniques. The dielectric coating 150 covers the central portion 102 and the periphery 101 of the filter 100, that is, all exposed portions of the filter 100, thereby protecting the filter 100 from environmental influences.

[0060] In other embodiments, the filter includes multiple corrosion-inhibiting layers disposed between a dielectric layer and a metal layer, which further protect the metal layer. (See reference...) Figure 2 The second embodiment of the filter 200 arranged on the substrate 210 is similar to the first embodiment of the filter 100, but also includes four corrosion inhibition layers 260 inserted between three dielectric layers 220 and two metal layers 230.

[0061] Each of the metal layers 230 is disposed between and adjacent to two corrosion-inhibiting layers 260, and is thus further protected from environmental influences. The corrosion-inhibiting layers 260 primarily inhibit corrosion of the metal layer 230 during the deposition process. In particular, the corrosion-inhibiting layers 260 protect the portion of the metal layer 230 in the optical path, preventing deterioration of the optical properties of the metal layer 230. Preferably, the tapered edge 231 of the metal layer 230 is protectively covered by the adjacent corrosion-inhibiting layer 260 and by the nearest dielectric layer 220. Therefore, the metal layer 230 is preferably substantially encapsulated by the adjacent corrosion-inhibiting layers 260 and by the nearest dielectric layer 220.

[0062] The second embodiment of filter 200 can be manufactured by a stripping process similar to that used in the first embodiment of filter 100. However, the multilayer stacked layers deposited in the fourth step correspond to the layers of filter 200. In particular, a corrosion inhibition layer 260 is deposited before and after each metal layer 230. Advantageously, the corrosion inhibition layer 260 inhibits corrosion, i.e., oxidation, of the metal layer 230 during the deposition of the dielectric layer 220.

[0063] The corrosion inhibition layer 260 can be deposited as a metal compound, such as a metal nitride or metal oxide layer, using one of the previously mentioned deposition techniques. Alternatively, the corrosion inhibition layer 260 can be formed by first depositing a suitable metal layer using one of the previously mentioned deposition techniques and then oxidizing the metal layer. Preferably, each corrosion inhibition layer 260 is formed by first depositing a suitable metal layer, oxidizing the metal layer, and then depositing a metal oxide layer. For example, the corrosion inhibition layer 260 can be formed by sputtering a suitable metal target, followed by oxidation, and then reactive sputtering of the suitable metal target in the presence of oxygen. Further details of the method for forming a corrosion inhibition layer are disclosed in U.S. Patent No. 7,133,197.

[0064] The filters of the present invention can have various optical designs. The optical designs of exemplary filters will be described in more detail thereafter. Generally, the optical design of a filter is optimized by selecting an appropriate number of layers, materials, and / or thickness for a particular passband.

[0065] Typically, filters comprise 2 to 6 metal layers, 3 to 7 dielectric layers, and optionally 4 to 12 corrosion-inhibiting layers. Generally, increasing the number of metal layers provides a passband with steeper edges but lower in-band transmittance.

[0066] The first layer in an optical design (i.e., the first layer deposited on the substrate) can be a metal layer or a dielectric layer. The last layer in an optical design (i.e., the last layer deposited on the substrate) is typically a dielectric layer. When the first layer is a metal layer, the filter can consist of n metal layers (M) and n dielectric layers (D) stacked in the order (M / D)n, where n ≥ 2. Alternatively, the filter can consist of n metal layers (M), n dielectric layers (D), and 2n corrosion inhibition layers (C) stacked in the order (C / M / C / D)n, where n ≥ 2. When the first layer is a dielectric layer, the filter can consist of n metal layers (M) and n+1 dielectric layers (D) stacked in the order D(M / D)n, where n ≥ 2. Alternatively, the filter may consist of n metal layers (M), n+1 dielectric layers (D), and 2n corrosion-inhibiting layers (C) stacked in the order D(C / M / C / D)n, where n≥2.

[0067] Each metal layer consists of a metal or alloy. Typically, each metal layer is composed of silver. Alternatively, each metal layer may be composed of a silver alloy. For example, a silver alloy consisting essentially of about 0.5 wt% gold, about 0.5 wt% tin, and the balance of silver can provide improved corrosion resistance. Typically, but not necessarily, the metal layers are composed of the same metal or alloy, but with different thicknesses. Generally, each metal layer has a physical thickness between about 5 nm and about 50 nm, preferably between about 10 nm and about 35 nm.

[0068] Each dielectric layer is composed of a dielectric material. Generally, each dielectric layer is composed of a high-refractive-index dielectric material that is transparent in the visible light spectral region (i.e., a dielectric material having a refractive index greater than about 1.65 at 550 nm). Suitable examples of high-refractive-index dielectric materials include titanium dioxide (TiO2), zirconium dioxide (ZrO2), niobium pentoxide (Nb2O5), tantalum pentoxide (Ta2O5), and mixtures thereof. Preferably, the high-refractive-index dielectric material is also UV-absorbing, i.e., absorbs in the near-UV spectral region. For example, a high-refractive-index dielectric material comprising TiO2 and / or Nb2O5, or composed of TiO2 and / or Nb2O5, can provide enhanced UV blocking, i.e., lower out-of-band transmittance in the near-UV spectral region. Preferably, the high-refractive-index dielectric material has a refractive index greater than about 2.0 at 550 nm, more preferably greater than about 2.35 at 550 nm. A higher refractive index is generally desirable. However, currently available transparent high-refractive-index dielectric materials typically have a refractive index of less than about 2.7 at 550 nm.

[0069] Typically, but not necessarily, the dielectric layers consist of the same dielectric material but have different thicknesses. Generally, each dielectric layer has a thickness between approximately 20 nm and approximately 300 nm. This physical thickness is chosen to correspond to the quarter-wavelength optical thickness (QWOT) required for the optical design. QWOT is defined as 4nt, where n is the refractive index of the dielectric material and t is the physical thickness. Generally, each dielectric layer has a QWOT between approximately 200 nm and approximately 2400 nm.

[0070] Each optional corrosion-inhibiting layer consists of a corrosion-inhibiting material. Generally, the corrosion-inhibiting layer consists of a corrosion-inhibiting dielectric material. Examples of suitable corrosion-inhibiting dielectric materials include silicon nitride (Si3N4), TiO2, Nb2O5, zinc oxide (ZnO), and mixtures thereof. Preferably, the corrosion-inhibiting dielectric material is a compound of a metal, such as a nitride or oxide, that has a higher galvanic potential than the metal or alloy of the metal layer.

[0071] Corrosion inhibition layers are typically thin enough to substantially avoid contributing to the optical design of the filter, especially when they absorb in the visible light spectral region. Generally, each corrosion inhibition layer has a physical thickness between about 0.1 nm and about 10 nm, preferably between about 1 nm and about 5 nm. Further details of suitable corrosion inhibition layers are disclosed in U.S. Patent No. 7,133,197.

[0072] The optional dielectric coating is composed of a dielectric material. The dielectric coating may be composed of the same dielectric material and may have the same thickness as the dielectric layer. Generally, the dielectric coating is composed of the same dielectric material as the last dielectric layer and has a thickness that is a portion of the designed thickness of the last dielectric layer (i.e., the thickness required for the optical design). In other words, the final dielectric layer of the optical design is distributed between the dielectric layer and the dielectric coating. For example, if the last dielectric layer has a designed thickness td and the dielectric coating has a coating thickness tc, such as 250 QWOT, then the actual thickness ta of the last dielectric layer is given by ta = td - tc.

[0073] refer to Figure 3 The filter 300 generally has a filter height h (i.e., the height of the center portion of the filter 300 from the substrate 310), said height being less than 1 μm, preferably less than 0.6 μm. Furthermore, the filter 300 generally has a filter width w (i.e., the width of the center portion of the filter 300), said width being less than 2 μm, preferably less than 1 μm. Advantageously, when multiple filters 300 are formed by a stripping process, the relatively small filter height allows for a smaller filter spacing. Generally, the filter 300 has a filter spacing d (i.e., the spacing between the center portions of the closest filters 300), said spacing being less than 2 μm, preferably less than 1 μm.

[0074] The filter is a metal-dielectric bandpass filter with high in-band transmittance and low out-of-band transmittance, i.e., an induced transmission filter. Generally, the filter has a maximum in-band transmittance greater than about 50%, an average out-of-band transmittance of less than about 2% in the near-UV spectral region, and an average out-of-band transmittance of less than about 0.3% in the infrared (IR) spectral region, between about 750 nm and about 1100 nm. Typically, the filter also has a low angular offset, i.e., a center wavelength shift when the incident angle changes from 0°. Generally, for a filter centered at 600 nm, the filter has an angular offset of less than about 5% or less than about 30 nm in amplitude at a 60° incident angle.

[0075] In some embodiments, the filter is a color filter having a relatively narrow color passband in the visible light spectrum. For example, the filter may be a red, green, blue, cyan, yellow, or magenta filter. In other embodiments, the filter is a photopic filter having a photopic passband in the visible light spectrum, i.e., a passband that simulates the spectral response of the human eye to relatively bright light. In still other embodiments, the filter is an IR blocking filter having a relatively wide passband in the visible light spectrum.

[0076] Exemplary red, green, and blue filters, i.e., exemplary RGB filter groups, have optical designs (i.e., number of layers, materials, and thicknesses) respectively in... Figure 4A , 4B And 4C are made into a table. An exemplary optical design of a visible filter is in Figure 4D The layers are arranged in a table. Each optical design is numbered starting from the first layer deposited on the substrate.

[0077] Each metal layer is composed of silver and has a physical thickness between approximately 13 nm and approximately 34 nm. Each dielectric layer is composed of a high-refractive-index dielectric material (H) and has a QWOT between approximately 240 nm and approximately 2090 nm. For example, the high-refractive-index dielectric material can be a mixture of Nb₂O₅ and TiO₂ with a refractive index of approximately 2.43 at 550 nm. Each corrosion-inhibiting layer is composed of ZnO and each layer has a physical thickness of approximately 2 nm.

[0078] When a high-refractive-index dielectric material has a refractive index of approximately 2.43 at 550 nm, the filter height for a red filter is 606 nm, for a green filter it is 531 nm, for a blue filter it is 252 nm, and for a clear-view filter it is 522 nm. These filter heights are significantly smaller than those of conventional all-dielectric filters.

[0079] exist Figure 5A and 5B The transmission spectra 570, 571, and 572 of exemplary red, green, and blue filters are plotted. The transmission spectrum 570 of the exemplary red filter includes a red passband centered at approximately 620 nm, the transmission spectrum 571 of the exemplary green filter includes a green passband centered at approximately 530 nm, and the transmission spectrum 572 of the exemplary blue filter includes a blue passband centered at approximately 445 nm.

[0080] exist Figure 5C The transmission spectra 573 and 574 of an exemplary photopic filter at incident angles from 0° to 60° are plotted. The transmission spectrum 573 of the exemplary photopic filter at a 0° incident angle includes a photopic passband centered at approximately 555 nm. In the transmission spectrum 574 of the exemplary photopic filter at a 60° incident angle, the photopic passband is centered at approximately 520 nm. In other words, the angular offset of the exemplary photopic filter at a 60° incident angle is approximately -25 nm.

[0081] Each exemplary filter has a maximum in-band transmittance greater than approximately 60%. Advantageously, the exemplary filters provide improved IR blocking relative to conventional dye-based and all-dielectric filters, reducing noise caused by IR leakage. Specifically, each exemplary filter has an average out-of-band transmittance of less than approximately 0.3% between approximately 750 nm and approximately 1100 nm (i.e., in the IR spectral region). The exemplary filters, particularly the exemplary red filter, also provide improved UV blocking relative to some conventional metal-dielectric color filters, reducing noise caused by UV leakage. Specifically, each exemplary filter has an average out-of-band transmittance of less than approximately 2% between approximately 300 nm and approximately 400 nm (i.e., in the near-UV spectral region).

[0082] The color gamut 680 of the exemplary RGB filter group is drawn together with the color gamut 681 of a conventional dye-based RGB filter group. Figure 6A The CIE xy chromaticity diagram is used for comparison. Advantageously, the color gamut 680 of the exemplary RGB filter group is significantly larger than the color gamut 681 of a conventional dye-based RGB filter group.

[0083] The color trajectory 682 of an exemplary red filter at incident angles from 0° to 60° is plotted together with the color trajectory 683 of a conventional all-dielectric red filter at incident angles from 0° to 60°. Figure 6B The color trajectory 684 of an exemplary photopic filter at incident angles from 0° to 60° is plotted in the CIE xy chromaticity diagram. Figure 6CIn the CIE xy chromaticity diagram. Advantageously, the angular offset of the exemplary filter is significantly smaller than that of a conventional all-dielectric filter.

[0084] The filters of this invention are particularly useful when incorporated as part of a sensor device. The sensor device can be any type of sensor device that includes one or more sensor elements in addition to the one or more filters of this invention. For example, the sensor device can be an ambient light sensor, a proximity sensor, or an image sensor. The one or more sensor elements can be any type of conventional sensor element. Generally, the one or more sensor elements are photoelectric sensors, such as photodiodes, charge-coupled device (CCD) sensor elements, or complementary metal-oxide-semiconductor (CMOS) sensor elements. The one or more sensor elements can be front-illuminated or back-illuminated.

[0085] The one or more filters are disposed on one or more sensor elements such that the filters filter the light supplied to the one or more sensor elements. Generally, each filter is disposed on one sensor element. In other words, each pixel of the sensor device generally includes a filter and a sensor element. Preferably, the one or more filters are disposed directly on the one or more sensor elements. For example, the one or more filters can be formed on the one or more sensor elements by a stripping process. However, in some instances, one or more coatings may be disposed between the one or more filters and the one or more sensor elements.

[0086] In some embodiments, the sensor device includes a single sensor element and a single filter disposed on the sensor element. (Reference) Figure 7 A first embodiment of the sensor device 790 includes a sensor element 711 and a filter 700 disposed on the sensor element 711. For example, the sensor device 790 may be an ambient light sensor, the sensor 711 may be a photodiode, and the filter 700 may be a daylight filter, for example... Figure 4D Examples of visible light filters or IR blocking filters.

[0087] In other embodiments, the sensor device includes a plurality of sensor elements and a plurality of filters arranged on the plurality of sensor elements. Generally, the sensor elements are arranged in an array. In other words, the sensor elements form a sensor array, such as a photodiode array, CCD array, CMOS array, or any other type of conventional sensor array. Furthermore, the filters are generally arranged in an array. In other words, the filters form a filter array, such as a color filter array (CFA). Preferably, the sensor array and the filter array are corresponding two-dimensional arrays, i.e., mosaic patterns. For example, the array may be a rectangular array with rows and columns.

[0088] Typically, these filters are substantially separate from each other. In other words, the peripheries of the filters usually do not touch each other. However, in some instances, the dielectric layers of the filters may inadvertently come into contact, while the metal layers, particularly the tapered edges, remain separate from each other.

[0089] Generally, multiple filters include filters of different types having passbands different from each other. For example, multiple filters may include color filters, such as red, green, blue, cyan, yellow, and / or magenta filters, bright-view filters, IR blocking filters, or combinations thereof. In some embodiments, multiple filters include color filters of different types forming a CFA. For example, multiple filters may include red, green, and blue filters forming an RGB filter array (e.g., a Bayer filter array), such as... Figures 4A to 4C Examples of red, green, and blue filters.

[0090] Advantageously, different types of filters may have different numbers of metal layers and / or different thicknesses of metal layers. In some embodiments, at least two of the different types of filters include different numbers of metal layers. In the same or other embodiments, at least two of the different types of filters have different metal layer thicknesses. For example, Figure 4C An example blue filter with Figure 4A and 4B The exemplary red and green filters have different numbers of metal layers. Furthermore, Figures 4A to 4C All the exemplary red, green and blue filters have different metal layer thicknesses than each other.

[0091] refer to Figure 8A second embodiment of the sensor device 890 includes a plurality of sensor elements 811 and a plurality of filters 800 and 804 arranged on the plurality of sensor elements 811. The plurality of filters 800 and 804 include a first type of filter 800 having a first passband and a second type of filter 804 having a second passband different from the first passband. For example, the sensor device 890 may be an image sensor, the plurality of sensor elements 811 may form a CCD array, and the plurality of filters 800 and 804 may form a Bayer filter array, only a portion of one row is shown in the figure. The first type of filter 800 may be a green filter, for example, by way of example. Figure 4B An exemplary green filter, while the second type of filter 804 can be a blue filter, such as the exemplary one. Figure 4C An example blue filter.

[0092] Of course, many other embodiments are conceivable without departing from the spirit and scope of the invention.

Claims

1. A bandpass filter, comprising: Multiple dielectric layers; Multiple metal layers stacked alternately with the plurality of dielectric layers, wherein Each of the plurality of metal layers has a tapered edge at the periphery of the filter that is protectively covered by one or more of the plurality of dielectric layers; Each of the plurality of metal layers is encapsulated by one or more of the plurality of dielectric layers, and Each of the plurality of metal layers is separated from the substrate of the bandpass filter using at least one of the plurality of dielectric layers; as well as Essentially, it encapsulates one or more corrosion-inhibiting layers of one of the plurality of metal layers.

2. The bandpass filter of claim 1, wherein the bandpass filter has a substantially flat top and sloping sides.

3. The bandpass filter of claim 1, wherein each of the plurality of metal layers has a tapered edge at the periphery of the bandpass filter, the tapered edge being encapsulated by one or more of the plurality of dielectric layers.

4. The bandpass filter according to claim 1, wherein the one or more corrosion inhibition layers comprise: A corrosion inhibition layer disposed between one of the plurality of dielectric layers and the metal layer.

5. The bandpass filter of claim 1, wherein each of the plurality of metal layers is encapsulated by the one or more corrosion-inhibiting layers.

6. The bandpass filter according to claim 1, further comprising: A dielectric coating deposited on the bandpass filter.

7. The bandpass filter of claim 1, wherein the bandpass filter is disposed on a sensor element.

8. The bandpass filter according to claim 7, wherein The sensor element is one of a plurality of sensor elements, and The bandpass filter is one of a plurality of filters.

9. The bandpass filter according to claim 8, wherein The plurality of sensor elements are arranged in a two-dimensional array, and The multiple filters are arranged in a corresponding two-dimensional array.

10. The bandpass filter of claim 8, wherein the plurality of filters comprises different types of filters having different passbands.

11. The bandpass filter of claim 10, wherein at least two of the different types of filters have at least one of the following: Different numbers of metal layers, or Different metal layer thicknesses.

12. The bandpass filter of claim 1, wherein the metal layer has a thickness different from at least one of the plurality of metal layers.

13. The bandpass filter of claim 1, wherein each of the plurality of metal layers is composed of silver or a silver alloy.

14. The bandpass filter of claim 1, wherein each of the plurality of dielectric layers is composed of a high refractive index dielectric material.

15. The bandpass filter of claim 14, wherein the high refractive index dielectric material is ultraviolet absorbing.

16. The bandpass filter of claim 1, wherein the bandpass filter is formed by a stripping process.

17. The bandpass filter of claim 16, wherein the stripping process comprises: A photoresist layer is applied to the substrate; Pattern the photoresist layer; Deposit multiple stacked layers on a patterned photoresist layer; A multilayer stack is deposited on the filter region of the substrate; Remove the photoresist layer; as well as Remove the multilayer stack deposited on the patterned photoresist layer.

18. The bandpass filter of claim 17, wherein patterning the photoresist layer includes forming overhangs in the photoresist layer.

19. The bandpass filter of claim 17, wherein the stripping process further comprises: A dielectric coating is deposited on the bandpass filter.

20. The bandpass filter of claim 1, wherein each of the one or more corrosion inhibition layers comprises ZnO.

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