HK40012097A - Metal-dielectric optical filter, sensor device, and fabrication method - Google Patents

Description

Metal-dielectric filter, sensor device and manufacturing method

The present application is a divisional application of the application entitled "metal-dielectric filter, sensor device, and manufacturing method" having an application date of 2014, 6/18/201480079828.9.

Technical Field

The present invention relates to a metal-dielectric filter, a sensor device comprising such a filter and a method of manufacturing such a filter.

Background

Optical sensors are used in optical sensor devices, such as image sensors, ambient light sensors, proximity sensors, color sensors, and UV sensors, to convert optical signals into electrical signals, allowing detection of optical signals or image acquisition. An optical sensor typically includes one or more sensor elements and one or more optical filters disposed on the one or more sensor elements.

For example, color image sensors include a plurality of color filters arranged in an array, i.e., a Color Filter Array (CFA). The CFA includes different types of color filters, e.g., red, green, blue (RGB) filters, having different color pass bands.

Conventionally, an absorption filter formed using a dye is used as a color filter. Unfortunately, such dye-based color filters have a relatively wide color pass band, which results in less vivid colors. Alternatively, a dichroic filter (i.e., an interference filter) formed of stacked dielectric layers may be used as the color filter. Such all-dielectric filters have a higher transmission level and a narrower color passband, which results in brighter and more vivid colors. However, as the angle of incidence changes, the color passband of the all-dielectric color filter experiences a relatively large center wavelength shift, which causes an undesirable shift in color.

Furthermore, all-dielectric color filters typically include a large number of stacked dielectric layers, and are relatively thick. As a result, all-dielectric color filters are expensive and difficult to manufacture. In particular, all-dielectric color filters are difficult to chemically etch. Therefore, a lift-off process is preferably used for patterning. Examples of lift-off processes for patterning all-dielectric color filters in CFAs are disclosed in U.S. patent No.5,120,622 to Hanrahan, issued 6-9.1992, in U.S. patent No.5,711,889 to Buchsbaum, issued 1-27.1998, in U.S. patent No.6,238,583 to Edlinger et al, issued 5-29.2001, in U.S. patent No.6,638,668 to Buchsbaum et al, issued 10-28.2003, and in U.S. patent No.7,648,808 to Buchsbaum et al, issued 1-19.2010. However, the lift-off process is typically limited to filter spacings that are about twice the height of the filter layer, which makes it difficult to achieve an all-dielectric CFA suitable for smaller color image sensors.

In addition to transmitting visible light in the color pass band, both dye-based color filters and all-dielectric color filters also transmit Infrared (IR) light that contributes to noise. Accordingly, color image sensors typically also include an IR blocking filter disposed over the CFA. IR blocking filters are also used in other optical sensor devices operating in the visible spectral range. Conventionally, an absorption filter formed of colored glass or a dichroic filter formed of stacked dielectric layers is used as an IR blocking filter. Alternatively, an induced transmission filter formed by stacking metal and dielectric layers may be used as the IR blocking filter. Examples of metal-dielectric IR blocking filters are disclosed in U.S. patent No.5,648,653 to Sakamoto et al, issued 7, 15, 1997 and in U.S. patent No.7,133,197 to okenfuss et al, issued 11, 7, 2006.

To avoid the use of an IR blocking filter, an induced transmission filter formed by stacking metal and dielectric layers may be used as a color filter. Metal-dielectric filters, such as metal-dielectric color filters, are inherently IR-blocking. Typically, metal-dielectric color filters have a relatively narrow color passband that does not shift significantly in wavelength with changes in angle of incidence. Furthermore, metal-dielectric color filters are typically much thinner than all-dielectric color filters. Examples of metal-dielectric color filters are disclosed in U.S. patent No.4,979,803 to McGuckin et al, published 12-25 of 1990, in U.S. patent No.6,031,653 to Wang, published 2-29 of 2000, in U.S. patent application No.2009/0302407 to gidn et al, published 12-10 of 2009, in U.S. patent application No.2011/0204463 to Grand, published 8-25 of 2011, and in U.S. patent application No.2012/0085944 to gidn et al, published 12-4 of 2012.

Typically, the metal layer in metal-dielectric filters (such as metal-dielectric color filters) is a silver or aluminum layer, which is environmentally unstable and degrades when exposed to even small amounts of water or sulfur. Chemically etching the silver layer exposes the edges of the silver layer to the environment, which causes deterioration. Thus, in most instances, the metal-dielectric color filters in the CFA are patterned by adjusting the thickness of only the dielectric layer to select different color pass bands of the metal-dielectric color filters. In other words, different types of metal-dielectric color filters, which are required to have different color pass bands, have the same number of silver layers as each other and the same thickness of silver layers as each other. Unfortunately, these requirements severely limit the possible optical designs of metal-dielectric color filters.

The present invention provides metal-dielectric filters that are not limited to these requirements, which are particularly suitable for use in image sensors and other sensor devices, such as ambient light sensors, proximity sensors, color sensors, and UV sensors.

Summary of The Invention

Accordingly, the present invention relates to an optical filter, disposed on a substrate, comprising: one or more dielectric layers; and one or more metal layers alternately stacked with one or more dielectric layers on the substrate, wherein each of the one or more metal layers has a chamfered edge extending along an entire periphery of the metal layer at a periphery of the optical filter, protectively covered by at least one of the one or more dielectric layers along the entire periphery of the metal layer.

The invention also relates to a sensor device comprising: one or more sensor elements; and one or more optical filters disposed on the one or more sensor elements, wherein each of the one or more optical filters comprises: one or more dielectric layers; and one or more metal layers alternately stacked with the one or more dielectric layers, wherein each of the one or more metal layers has a chamfered edge extending along an entire periphery of the metal layer at a periphery of the optical filter, protectively covered by at least one of the one or more dielectric layers along the entire periphery of the metal layer.

The invention also relates to a method of manufacturing an optical filter, the method comprising: providing a substrate; applying a photoresist layer to a substrate; patterning the photoresist layer to expose a filter region of the substrate, thereby forming an overhang in the patterned photoresist layer around the filter region; depositing a multi-layer stack comprising one or more metal layers alternately stacked with one or more dielectric layers onto the patterned photoresist layer and the filter region of the substrate; removing the patterned photoresist layer and a portion of the multilayer stack on the patterned photoresist layer such that the portion of the multilayer stack remaining on the filter region of the substrate forms a filter, wherein each of the one or more metal layers in the filter has a chamfered edge extending along an entire periphery of the metal layer at a periphery of the filter, which is protectively covered by at least one of the one or more dielectric layers along the entire periphery of the metal layer.

The invention also includes the following embodiments:

1) an optical filter disposed on a substrate, the optical filter comprising:

one or more dielectric layers; and

one or more metal layers alternately stacked with the one or more dielectric layers on the substrate, wherein each of the one or more metal layers has a chamfered edge extending along an entire periphery of the metal layer at a periphery of the optical filter, protectively covered by at least one of the one or more dielectric layers along an entire periphery of the metal layer.

2) The optical filter of 1), wherein the one or more dielectric layers consist of a plurality of dielectric layers, and wherein the one or more metal layers consist of a plurality of metal layers.

3) The optical filter of claim 2), wherein the optical filter has a substantially flat top and sloped sides, and wherein the sides of the optical filter are sloped at an angle of less than about 45 ° relative to horizontal.

4) The filter of claim 3), wherein the sides of the filter are inclined to the horizontal at an angle of less than about 20 °.

5) The optical filter of claim 2), wherein the optical filter has a filter layer height of less than about 1 μm.

6) The optical filter of claim 2), wherein each of the plurality of metal layers is substantially uniform in thickness throughout a central portion of the optical filter.

7) The optical filter of 2), wherein each of the plurality of metal layers is composed of silver, a silver alloy, or aluminum.

8) The optical filter of claim 7), wherein the optical filter is a color filter, a photopic filter, an infrared blocking filter, or an ultraviolet filter.

9) The optical filter of 2), wherein the plurality of dielectric layers includes a top dielectric layer protectively covering the chamfered edges of the plurality of metal layers.

10) The sensor device of 9), wherein the top dielectric layer has a physical thickness greater than about 40 nm.

11) A sensor apparatus, comprising:

one or more first sensor elements; and

one or more first optical filters disposed on the one or more first sensor elements, wherein each of the one or more first optical filters comprises:

one or more dielectric layers; and

one or more metal layers alternately stacked with the one or more dielectric layers, wherein each of the one or more metal layers has a chamfered edge extending along an entire periphery of the metal layer at a periphery of the optical filter, protectively covered by at least one of the one or more dielectric layers along the entire periphery of the metal layer.

12) The sensor device of claim 11), wherein the one or more dielectric layers consists of a plurality of dielectric layers, and wherein the one or more metal layers consists of a plurality of metal layers.

13) The sensor device of 12), wherein the one or more first optical filters are disposed on the passivation layer of the one or more first sensor elements.

14) The sensor device of 13), further comprising an encapsulation layer disposed over the one or more first optical filters and the one or more first sensor elements.

15) The sensor device of 12), wherein the sensor device is an image sensor, an ambient light sensor, a proximity sensor, a color sensor, an ultraviolet sensor, or a combination thereof.

16) The sensor device of claim 12), further comprising:

one or more second sensor elements; and

one or more second filters disposed on the one or more second sensor elements, wherein the one or more second filters are more environmentally durable than the one or more first filters, and wherein the one or more second filters partially overlap the one or more first filters to protectively cover a periphery of the one or more first filters.

17) The sensor device of 16), wherein the one or more first filters have a substantially flat top and sloped sides, and wherein the one or more second filters extend over the sloped sides of the one or more first filters.

18) The sensor device of 16), wherein each of the plurality of metal layers is comprised of silver or a silver alloy.

19) The sensor device of 18), wherein the one or more first optical filters are one or more color filters, photopic filters, infrared blocking filters, or a combination thereof.

20) The sensor device of 18), wherein the one or more second filters are one or more all-dielectric filters, aluminum-dielectric filters, silicon-dielectric filters, hydrogenated silicon-dielectric filters, or a combination thereof.

21) The sensor device of 20), wherein the one or more second filters are one or more ultraviolet filters, near-infrared filters, or a combination thereof.

22) A method of manufacturing an optical filter, the method comprising:

providing a substrate;

applying a photoresist layer to the substrate;

patterning the photoresist layer to expose a filter region of the substrate, thereby forming an overhang in the patterned photoresist layer surrounding the filter region;

depositing a multi-layer stack comprising one or more metal layers alternately stacked with one or more dielectric layers onto the patterned photoresist layer and the filter region of the substrate;

removing the patterned photoresist layer and a portion of the multilayer stack over the patterned photoresist layer such that a portion of the multilayer stack remaining on the filter region of the substrate forms the filter, wherein each of the one or more metal layers in the filter has a chamfered edge extending along an entire periphery of the metal layer at a periphery of the filter and protectively covered by at least one of the one or more dielectric layers along an entire periphery of the metal layer.

23) The method of 22), wherein the one or more metal layers consists of a plurality of metal layers, and wherein the one or more dielectric layers consists of a plurality of dielectric layers.

24) The method of 23), wherein the substrate is a sensor element.

25) The method of 23), wherein the overhang is at least 2 μ ι η.

26) The method of 25), wherein the overhang is at least 4 μ ι η.

27) The method of 23), wherein the photoresist layer comprises a bottom release layer and a top photosensitive layer.

28) The method of 27), wherein the multi-layer stack is deposited to a thickness of less than about 70% of the thickness of the bottom release layer.

29) The method of 28), wherein the multi-layer stack is deposited to a thickness of less than about 30% of the thickness of the bottom release layer.

30) The method of 23), further comprising:

forming a second filter on the substrate that is more environmentally durable than the first filter such that the second filter partially overlaps the first filter to protectively cover a periphery of the first filter.

Drawings

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

FIG. 1A is a schematic diagram of a cross-section of a first embodiment of an optical filter;

FIGS. 1B-1G are schematic diagrams of steps of a method of making the optical filter of FIG. 1A;

FIG. 2 is a schematic diagram of a cross-section of a second embodiment of an optical filter;

FIG. 3 is a schematic diagram of a cross-section of a plurality of filters;

FIG. 4A is a table of layer numbers, materials, and thicknesses for an exemplary red filter;

FIG. 4B is a table of the number of layers, materials, and thicknesses of an exemplary green filter;

FIG. 4C is a table of the number of layers, materials, and thicknesses of an exemplary blue filter;

FIG. 4D is a table of the number of layers, materials, and thicknesses of an exemplary photopic Filter;

FIGS. 5A and 5B are plots of the transmission spectra of the exemplary red, green, and blue filters of FIGS. 4A-4C;

FIG. 5C is a plot of the transmission spectra of the exemplary photopic vision filter of FIG. 4D at incident angles of 0 to 60;

FIG. 6A is a plot of the color gamut of the exemplary red, green, and blue (RGB) filter sets and conventional dye-based RGB filter sets of FIGS. 4A-4C;

FIG. 6B is a plot of the color locus for the exemplary red filter of FIG. 4A and a conventional all-dielectric red filter at an angle of incidence of 0 to 60;

FIG. 6C is a plot of color trajectories for the exemplary photopic filter of FIG. 4D at incident angles of 0 to 60;

FIG. 7 is a schematic diagram of a cross-section of a first embodiment of a sensor device;

FIG. 8 is a schematic illustration of a cross-section of a second embodiment of a sensor device;

FIGS. 9A and 9B are scanning electron micrographs of cross sections of a continuous coating deposited on a patterned photoresist layer and a substrate;

FIG. 9C is an optical micrograph of a top view of a filter formed from the continuous coating in FIGS. 9A and 9B showing corrosion after exposure to high humidity and temperature;

FIG. 10 is a scanning electron micrograph of a cross-section of a non-continuous coating deposited on a patterned photoresist layer and a substrate;

11A and 11B are scanning electron micrographs of cross sections of a non-continuous coating deposited on a patterned photoresist layer and substrate having a thicker bottom release layer and larger overhang portions;

FIG. 12 is a table of layer numbers, materials, and thicknesses for exemplary ultraviolet A (UVA), ultraviolet B (UVB), and 220nm center wavelength filters;

fig. 13A is a plot of the transmission spectrum of the exemplary UVA filter of fig. 12 at incident angles from 0 ° to 60 °;

fig. 13B is a plot of the transmission spectrum of the exemplary UVB filter of fig. 12 at an incident angle of 0 ° to 60 °;

FIG. 13C is a plot of transmission spectra for the exemplary 220nm center wavelength filter of FIG. 12 at incident angles of 0 to 60;

FIG. 14 is a plot of transmission spectra of an exemplary photopic filter at incident angles from 0 to 60;

FIG. 15A is a schematic illustration of a cross-section of a third embodiment of a sensor apparatus;

FIG. 15B is a schematic diagram of a top view of the sensor apparatus of FIG. 15A;

FIG. 15C is a schematic diagram of a top view of an alternative layout of the sensor apparatus of FIG. 15A; and

fig. 16 is a schematic diagram of a top view of a fourth embodiment of a sensor device.

Detailed Description

The present invention provides a metal-dielectric filter with a protective metal layer that is particularly suitable for use in sensor devices such as image sensors, ambient light sensors, proximity sensors, color sensors, or Ultraviolet (UV) sensors. The optical filter includes one or more dielectric layers and one or more metal layers that are alternately stacked. The metal layer is inherently protected by the dielectric layer. In particular, the metal layer has a chamfered edge that is protectively covered by one or more of the dielectric layers. Thus, the metal layer has increased resistance to environmental degradation, resulting in an environmentally more durable filter.

In some embodiments, the one or more dielectric layers and the one or more metal layers are stacked without any intermediate layers. Referring to fig. 1A, a first embodiment of an optical filter 100 disposed on a substrate 110 includes three dielectric layers 120 and two metal layers 130 alternately stacked. Each metal layer 130 is disposed between and adjacent to two dielectric layers 120 and is thereby protected from the environment. Dielectric layer 120 and metal layer 130 are continuous layers that do not have any microstructures formed therein.

The metal layer 130 has a chamfered edge 131 at the periphery 101 of the optical filter 100. In other words, the metal layer 130 is substantially uniform in thickness throughout the central portion 102 of the optical filter 100, but gradually decreases in thickness at the periphery 101 of the optical filter 100. The chamfered edge 131 extends along the entire edge of the metal layer 130 at the periphery 101 of the optical filter 100. Likewise, the dielectric layer 120 is substantially uniform in thickness throughout the central portion 102 of the optical filter 100, but gradually decreases in thickness at the periphery 101 of the optical filter 100. Thus, the central portion 102 of the filter 100 is substantially uniform in height, whereas the periphery 101 of the filter 100 is slanted. In other words, the filter 100 has a substantially flat top and sloped sides. Typically, the sides of the filter 100 are inclined from the horizontal at an angle of less than about 45 °. Preferably, the sides of the filter 100 are inclined from the horizontal at an angle of less than about 20 °, and more preferably, at an angle of less than about 10 °.

Advantageously, the beveled edge 131 of the metal layer 130 is not exposed to the environment. Instead, the chamfered edge 131 of the metal layer 130 is protectively covered by one or more of the dielectric layers 120 along the entire periphery of the metal layer 130. The one or more dielectric layers 120 inhibit environmental deterioration (e.g., corrosion) of the metal layer 130 (e.g., by inhibiting diffusion of sulfur and water into the metal layer 130). Preferably, the metal layer 130 is substantially encapsulated by the dielectric layer 120. More preferably, the beveled edges 131 of the metal layer 130 are protectively covered by the adjacent dielectric layer 120, and the metal layer 130 is substantially encapsulated by the adjacent dielectric layer 120. In some examples, the top dielectric layer 120 (i.e., the dielectric layer 120 on top of the optical filter 100) protectively covers the beveled edges 131 of all of the underlying metal layers 130.

Referring to fig. 1B through 1G, the first embodiment of the optical filter 100 may be manufactured through a lift-off process. Referring specifically to fig. 1B, in a first step, a substrate 110 is provided. Referring specifically to FIG. 1C, in a second step, a photoresist layer 140 is applied to the substrate 110. Typically, the photoresist layer 140 is applied by spin coating or spray coating.

Referring specifically to fig. 1D, in a third step, the photoresist layer 140 is patterned to expose an area of the substrate 110 where the filter 100 is to be disposed, i.e., a filter area. Other areas of the substrate 110 remain covered by the patterned photoresist layer 140. Typically, the photoresist layer 140 is patterned by first exposing regions of the photoresist layer 140 overlying the filter regions of the substrate 110 to UV light through a mask, and then developing (i.e., etching) the exposed regions of the photoresist layer 140 using a suitable developer or solvent.

The photoresist layer 140 is patterned in such a manner that an overhang 141 (i.e., an undercut) surrounding the filter region is formed in the patterned photoresist layer 140. Typically, overhang 141 is formed by chemically (e.g., by using a suitable solvent) modifying the top portion of photoresist layer 140 such that the top portion of photoresist layer 140 develops more slowly than the bottom portion. Alternatively, the overhang 141 may be formed by applying a double photoresist layer 140 consisting of a top layer that is developed more slowly and a bottom layer that is developed more quickly to the substrate 110.

As shown in fig. 1E, overhang 141 should be large enough to ensure that the coating (i.e., multilayer stack 103) is substantially deposited on patterned photoresist layer 140 and that substrate 110 is not continuous from substrate 110 to patterned photoresist layer 140. Overhang 141 is typically greater than 2 μm, preferably greater than 4 μm. Generally, the coating should not cover the sides of the patterned photoresist layer 140.

Referring to fig. 9A and 9B, when the coating 903 is continuous over the substrate 910 and the patterned photoresist layer 940, the coating 903 is damaged at the bottom edge of the patterned photoresist layer 940 during subsequent stripping of the photoresist layer 940 and the portion of the coating 903 over the photoresist layer 940, exposing the edge of the optical filter formed by the coating 903 (specifically the edge of the metal layer of the optical filter) to the environment. Unfortunately, as shown in fig. 9C for a filter 900 comprising silver, the exposed edges are susceptible to environmental attack, e.g., when exposed to high humidity and temperature, which results in corrosion.

Referring to fig. 10, in an embodiment where a non-continuous coating 1003 is provided, the photoresist layer has a bilayer structure and includes a top layer 1042 and a bottom layer 1043. The top layer 1042 is photosensitive and can be patterned by selective exposure to UV light. The bottom layer 1043 is typically not photosensitive and acts as a release layer. Suitable examples of resists include AZ electronic material nlofs 2020 for top photoresist layer 1042 and LOR 10B from Microchem for bottom release layer 1043.

When the photoresist layer is developed, the length of the overhang 1041 is constrained by the development time. In fig. 10, the development time is selected to provide overhang 1041 of about 3 μm. Preferably, the thickness of the bottom release layer 1043 is greater than about 500nm and the overhang 1041 is greater than about 2 μm. To ensure clean lift-off (i.e., lift-off without damaging the deposited coating 1003), the thickness of the coating 1003 should generally be less than about 70% of the thickness of the bottom release layer 1043. In fig. 10, the thickness of the bottom release layer 1043 is about 800nm, the thickness of the top photosensitive layer 1042 is about 2 μm, and the thickness of the coating is about 500 nm. The side of the optical filter 1000 below the overhang 1041 is inclined at an angle of about 10 °.

Referring to fig. 11A and 11B, in some examples, using a thicker bottom release layer 1143, larger overhang 1141 is created by using a longer development time (e.g., about 80s to about 100s for some processes). These features improve edge durability by reducing the slope of the sides of the filter 1100 and increasing the thickness of the top dielectric layer 1121 at the periphery of the filter 1100. In FIG. 11A, the development time is selected to provide overhang 1141 of about 6 μm. Preferably, the thickness of bottom release layer 1143 is greater than about 2 μm and overhang 1141 is greater than about 4 μm. The thickness of the coating 1103 should generally be less than about 30% of the thickness of the underlying release layer 1143. In fig. 11B, the thickness of the bottom release layer 1143 is about 2.6 μm, the thickness of the top photosensitive layer 1142 is about 2 μm, and the thickness of the coating 1103 is about 500 nm. The side of filter 1100 below overhang 1141 is tilted at an angle of about 5 °.

Referring specifically to FIG. 1E, in a fourth step, the multi-layer stack 103 is deposited as a non-continuous coating onto the patterned photoresist layer 140 and the filter regions of the substrate 110. A portion of the multilayer stack 103 disposed on the filter area of the substrate 110 forms the filter 100. The layers of the multi-layer stack 103 corresponding to the layers in the optical filter 100 may be deposited by using various deposition techniques, such as: evaporation, e.g., thermal evaporation, electron beam evaporation, plasma assisted evaporation, or reactive ion evaporation; sputtering, for example, 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 may be deposited by using different deposition techniques. For example, the metal layer 130 may be deposited by sputtering of a metal target, and the dielectric layer 120 may be deposited by reactive sputtering of a metal target in the presence of oxygen.

Since the overhang 141 shields the periphery of the filter area of the substrate 110, the deposition layer gradually decreases in thickness toward the periphery 101 of the filter 100. Overhang 141 creates a soft roll-off of the coating towards the periphery 101 of the filter 100. When the dielectric layer 120 is deposited onto the metal layer 130, the dielectric layer 120 covers not only the top surface of the metal layer 130, but also the chamfered edge 131 of the metal layer 130, thereby protecting the metal layer 130 from the environment. In addition, the top dielectric layer 120 generally acts as a protective layer for the underlying metal layer 130. For example, as shown in fig. 11A, in the embodiment of fig. 11A, a top dielectric layer 1121 having a thickness of approximately 100nm extends over and protectively covers the underlying less durable metal layer (specifically, the beveled edges of the metal layer).

Referring specifically to fig. 1F, in a fifth step, a portion of the multi-layer stack 103 on the patterned photoresist layer 140 is removed, i.e., stripped, along with the photoresist layer 140. Typically, the photoresist layer 140 is stripped using a suitable stripper or solvent. A part of the multilayer stack 103 remaining on the filter region of the substrate 110 forms the filter 100. The substrate 110 may for example be a conventional sensor element.

It should be noted that the lift-off process of fig. 1B-1F may also be used to form a plurality of filters 100 of the same type on the substrate 110 simultaneously, i.e., with the same optical design. Furthermore, the lift-off process may be repeated to subsequently form one or more different types of filters on the same substrate 110, i.e., having different optical designs. In some examples, one or more environmentally more durable optical filters may be subsequently formed on the substrate 110 such that they partially overlap one or more environmentally less durable optical filters 100 by using a lift-off process, or in some examples by using a dry or wet etch process, as will be explained in further detail below. Thus, a filter array may be formed on the substrate 110. The substrate 110 may be, for example, a conventional sensor array.

Referring specifically to fig. 1G, in an optional sixth step, an additional protective coating 150 is deposited on the optical filter 100. The protective coating 150 may be deposited by using one of the deposition techniques mentioned so far. The protective coating 150 covers both the central portion 102 and the periphery 101 of the optical filter 100 (i.e., all exposed portions of the optical filter 100), thereby protecting the optical filter 100 from the environment.

In other embodiments, the optical filter includes a plurality of corrosion inhibiting layers disposed between the dielectric layer and the metal layer to further protect the metal layer. Referring to fig. 2, a second embodiment of an optical filter 200 disposed on a substrate 210 is similar to the first embodiment of the optical filter 100, but further includes four corrosion-inhibiting layers 260 interposed between three dielectric layers 220 and two metal layers 230.

Each of the metal layers 230 is disposed between two corrosion inhibiting layers 260 and adjacent to the two corrosion inhibiting layers 260 and is thereby further protected from the environment. The corrosion inhibiting layer 260 primarily inhibits corrosion of the metal layer 230 during the deposition process. Specifically, the corrosion inhibiting layer 260 protects portions of the metal layer 230 in the optical path, inhibiting attenuation of the optical properties of the metal layer 230. Preferably, the beveled edge 231 of the metal layer 230 is protectively covered by the adjacent corrosion-inhibiting layer 260 and by the proximate dielectric layer 220. As such, the metal layer 230 is preferably substantially encapsulated by the adjacent corrosion-inhibiting layer 260 and by the proximate dielectric layer 220.

The second embodiment of the optical filter 200 may be manufactured by a lift-off process similar to that used to manufacture the first embodiment of the optical filter 100. However, the layers in the multilayer stack deposited in the fourth step correspond to the layers in the optical filter 200. Specifically, corrosion inhibiting layers 260 are deposited before and after each metal layer 230. Advantageously, the corrosion-inhibiting layer 260 inhibits corrosion (i.e., oxidation) of the metal layer 230 during deposition of the dielectric layer 220. The corrosion-inhibiting layer 260 is particularly useful when the metal layer 230 comprises silver or aluminum. In such an embodiment, the corrosion-inhibiting layer 260 inhibits the reaction between silver or aluminum in the metal layer 230 and oxygen in the dielectric layer 220 to form silver oxide or aluminum oxide.

The corrosion-inhibiting layer 260 may be deposited as a metal compound (e.g., metal nitride or metal oxide) layer by using one of the deposition techniques mentioned so far (e.g., reactive sputtering). Alternatively, the corrosion-inhibiting layer 260 may be formed by first depositing a suitable metal layer using one of the deposition techniques mentioned so far, and then oxidizing the metal layer. Each corrosion-inhibiting layer 260 on top of the metal layer 230 is preferably formed by first depositing a suitable metal layer, oxidizing the metal layer, and then depositing a metal oxide layer. For example, these corrosion-inhibiting layers 260 can be formed by sputtering of a suitable metal target in the presence of oxygen, followed by oxidation of the suitable metal target, followed by reactive sputtering of the suitable metal target. Additional details of methods of forming corrosion inhibiting layers are provided below and disclosed in U.S. patent No.7,133,197.

The optical filter of the present invention may have various optical designs. The optical design of an exemplary optical filter will be described in further detail below. In general, the optical design of the filter is optimized for a particular passband by selecting the appropriate number of layers, materials, and/or thicknesses.

The optical filter includes at least one metal layer and at least one dielectric layer. Optical filters often include multiple metal layers and multiple dielectric layers. Typically, the optical filter comprises 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 gives a steeper edge to the passband, but lower in-band transmission.

The first layer or underlayer in the optical design (i.e., the first layer deposited on the substrate) may be a metal layer or a dielectric layer. The last or top layer in the optical design (i.e., the last layer deposited on the substrate) is often a dielectric layer. When the bottom layer is a metal layer, the filter can be made of a material according to (M/D)_nN metal layers (M) and n dielectric layers (D) stacked in this order (where n.gtoreq.1). Alternatively, the filter may be made of a material in accordance with (C/M/C/D)_nN metal layers (M), n dielectric layers (D), and 2n corrosion-inhibiting layers (C), wherein n is 1 or more. When the bottom layer is a dielectric layer, the filter can be made in accordance with D (M/D)_nN metal layers (M) and n +1 dielectric layers (D), wherein n is more than or equal to 1. Alternatively, the filter may be made of a material in accordance with D (C/M/C/D)_nN metal layers (M), n +1 dielectric layers (D), and 2n corrosion-inhibiting layers (C), wherein n is 1 or more.

Each of the metal layers is composed of a metal or an alloy. In some embodiments, each of the metal layers is comprised of silver. Alternatively, each of the metal layers 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 silver may provide improved corrosion resistance. In other embodiments, each of the metal layers is comprised of aluminum. The choice of metal or alloy depends on the application. Silver is often preferred for filters having a passband in the visible spectral region and aluminum is often preferred for filters having a passband in the UV spectral region, but silver may sometimes be used when the center of the passband is at a wavelength greater than about 350 nm.

Typically, but not necessarily, the metal layers are composed of the same metal or alloy, but the metal layers have different thicknesses. Typically, each of the metal layers has a physical thickness of between about 5nm and about 50nm (preferably, between about 10nm and about 35 nm).

Each of the dielectric layers is composed of a dielectric material that is transparent in a pass band of the optical filter.

For filters having a passband in the visible region, typically each of the dielectric layers is composed of a high index dielectric material transparent in the visible region having a refractive index greater than about 1.65 at 550 nm. Suitable examples of high refractive index dielectric materials for such filters include titanium dioxide (TiO)₂) Zirconium dioxide (ZrO)₂) Hafnium oxide (HfO)₂) Niobium pentoxide (Nb)₂O₅) Tantalum pentoxide (Ta)₂O₅) And mixtures thereof. Preferably, the high index dielectric materials used for such filters are also UV-absorbing, i.e., absorbing in the near UV spectral region. For example, including TiO₂And/or Nb₂O₅Or from TiO₂And/or Nb₂O₅The constituent high index dielectric materials may provide enhanced UV blocking, i.e., lower out-of-band transmission in the near UV spectral region. Preferably, the high index dielectric material has a refractive index greater than about 2.0 at 550nm, and more preferably, greater than about 2.35 at 550 nm. Higher refractive indices are generally desirable. However, currently available transparent high index dielectric materials typically have a refractive index of less than about 2.7 at 550 nm.

For filters having a passband in the UV spectral region, each of the dielectric layers is typically composed of an intermediate index dielectric material having a refractive index between about 1.4 and 1.65 at 300nm, or preferably a high index dielectric material having a refractive index greater than 1.65 at 300nm (or more preferably a refractive index greater than about 2.2 at 300nm that is transparent in the UV spectral region). For having a UV lightSuitable examples of medium and high index dielectric materials for the filter in the passband of the spectral region include: ta₂O₅Hafnium oxide (HfO)₂) Aluminum oxide (Al)₂O₃) Silicon dioxide (SiO)₂) Sc, Sc trioxide₂O₃Yttrium oxide (Y)₂O₃)、ZrO₂Magnesium dioxide (MgO2), magnesium fluoride (MgF)₂) Other fluorides, and mixtures thereof. For example, Ta may be used₂O₅A high refractive index dielectric material used as a pass band having a center wavelength at a wavelength higher than about 340nm, and HfO may be used₂A high refractive index dielectric material for use as a passband centered at a wavelength below about 400 nm.

Typically, but not necessarily, the dielectric layers are composed of the same dielectric material, but the dielectric layers have different thicknesses. Typically, each of the dielectric layers has a physical thickness between about 20nm and about 300 nm. Preferably, the top dielectric layer has a physical thickness greater than about 40nm (more preferably, greater than about 100nm) to enable the top dielectric layer to act as a protective layer for the underlying metal layer. The physical thickness of each dielectric layer is selected to correspond to a quarter-wave 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. Typically, each of the dielectric layers has a QWOT between about 200nm and about 2400 nm.

Each of the optional corrosion inhibiting layers is comprised of a corrosion inhibiting material. Typically, the corrosion-inhibiting layer is composed of a corrosion-inhibiting dielectric material. Examples of suitable corrosion inhibiting dielectric materials include: silicon nitride (Si)₃N₄)、TiO₂、Nb₂O₅Zinc oxide (ZnO), and mixtures thereof. Preferably, the corrosion-inhibiting dielectric material is a compound, such as a nitride or oxide of a metal having a higher galvanic potential than the metal or alloy of the metal layer.

In some examples, the corrosion-inhibiting layer below the metal layer is comprised of ZnO, while the corrosion-inhibiting layer above the metal layer includes a very thin layer comprised of zinc (e.g., having a thickness of less than 1 nm) and a thin layer comprised of ZnO. A zinc layer is deposited on the metal layer and then post-oxidized to prevent optical absorption. The ZnO layers below and above the metal layer are typically deposited by reactive sputtering. Advantageously, depositing the zinc layer on the metal layer prior to depositing the ZnO layer prevents the metal layer from being exposed to reactive ionized oxygen species generated during reactive sputtering. The zinc layer preferentially absorbs oxygen, which inhibits oxidation of the metal layer.

The corrosion-inhibiting layer is typically suitably thin to substantially avoid affecting the optical design of the filter (particularly when the corrosion-inhibiting layer is absorbing in the visible region of the spectrum). Typically, each of the corrosion-inhibiting layers has a physical thickness between about 0.1nm and about 10nm (preferably, between about 1nm and about 5 nm). Additional details of suitable corrosion inhibiting layers are disclosed in U.S. patent No.7,133,197.

The optional protective coating is typically comprised of a dielectric material. The protective coating may be composed of the same dielectric material, and the protective coating may have the same thickness range as the dielectric layer. The protective coating layer is often composed of the same dielectric material as the top dielectric layer, and has a thickness that is a fraction of the design thickness of the top dielectric layer (i.e., the thickness required for the optical design). In other words, the top dielectric layer of the optical design is divided between the dielectric layer and the dielectric protective coating. Alternatively, the protective coating may be composed of an organic material (e.g., epoxy).

Referring to fig. 3, the optical filter 300 generally has a filter layer height h of less than 1 μm (preferably, less than 0.6 μm), i.e., a height of a central portion of the optical filter 300 from the substrate 310. It should be noted that the filter height generally corresponds to the thickness of the deposited coating mentioned so far. When used in an image sensor, the filter 300 typically has a filter width w of less than 2 μm (preferably, less than 1 μm), i.e., the width of the central portion of the filter 300. Advantageously, the relatively small filter layer height allows for smaller filter spacing when multiple filters 300 are formed by a lift-off process. In general, the filters 300 in the image sensor have a filter interval d of less than 2 μm (preferably, less than 1 μm), that is, an interval between central portions of the nearest filters 300. When used in other sensor devices having larger pixel sizes, the filter width may be from about 50 μm to about 100 μm.

The filter is a metal dielectric bandpass filter (i.e., an induced transmission filter) that has a high in-band transmission and a low out-of-band transmission. In some embodiments, the filter is a color filter having a relatively narrow color passband in the visible spectral region. 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 pass band (i.e., a pass band that matches a photopic luminance efficiency function that models the spectral response of the human eye to relatively bright light in the visible spectral region). In still other embodiments, the filter is an IR blocking filter having a relatively wide passband in the visible spectral region.

In such embodiments, the optical filter typically has a maximum in-band transmission of greater than about 50%, an average out-of-band transmission of less than about 2% between about 300nm and about 400nm (i.e., in the near UV spectral region), and an average out-of-band transmission of less than about 0.3% between about 750nm and about 1100nm (i.e., in the Infrared (IR) spectral region). In contrast, conventional all-dielectric color filters and photopic filters typically do not inherently block IR. Typically, in such embodiments, the filter also has a low angular shift, i.e., a shift in the center wavelength as the angle of incidence changes from 0 °. Typically, the filter has an angular offset of less than about 5% at an angle of incidence of 60 °, or an offset of about 30nm in size for a filter centered at 600nm wavelength. In contrast, conventional all-dielectric color filters and photopic filters are typically very angle sensitive.

The optical designs (i.e., number of layers, materials, and thicknesses) for the exemplary red, green, and blue filters (i.e., the exemplary RGB filter set) are tabulated in fig. 4A, 4B, and 4C, respectively. The optical design of an exemplary photopic vision filter is tabulated in fig. 4D. The layers of each optical design are counted starting with the first or bottom layer deposited on the substrate.

Each of the metal layers is comprised of silver, and the metal layers have a physical thickness between about 13nm and about 34 nm. Each of the dielectric layers is composed of a high index dielectric material (H), and the dielectric layers have a QWOT between about 240nm and about 2090 nm. For example, the high index dielectric material may be Nb with a refractive index of about 2.43 at 550nm₂O₅And TiO₂A mixture of (a). Each of the corrosion-inhibiting layers is composed of ZnO, and each has a physical thickness of about 2 nm.

When the high refractive index dielectric material has a refractive index of about 2.43 at 550nm, the filter height of the red filter is 606nm, the filter height of the green filter is 531nm, the filter height of the blue filter is 252nm, and the filter height of the photopic filter is 522 nm. These filter heights are much smaller than those of conventional all-dielectric color filters and photopic filters.

Transmission spectra 570, 571, and 572 of exemplary red, green, and blue filters are depicted in fig. 5A and 5B, respectively. The transmission spectrum 570 of the exemplary red filter includes a red passband centered at about 620nm, the transmission spectrum 571 of the exemplary green filter includes a green passband centered at about 530nm, and the transmission spectrum 572 of the exemplary blue filter includes a blue passband centered at about 445 nm.

Transmission spectra 573(0 °) and 574(60 °) of the exemplary photopic filters at incidence angles of 0 ° to 60 ° are plotted in fig. 5C. The transmission spectrum 573 of the exemplary photopic filter at an angle of incidence of 0 ° includes a photopic pass band centered at about 555 nm. In the transmission spectrum 574 of the exemplary photopic filter at an angle of incidence of 60 °, the center wavelength of the photopic passband is at about 520 nm. In other words, the angular offset of the exemplary photopic filter at an angle of incidence of 60 ° is about 25 nm. Beneficially, the angular offset of the exemplary photopic vision filter is much smaller than that of conventional all-dielectric photopic vision filters.

Each of the exemplary color filters and photopic vision filters has a maximum in-band transmission greater than about 60%. Beneficially, the exemplary color filters and photopic filters provide improved IR blocking and reduced noise due to IR leakage compared to conventional dye-based filters and all-dielectric color filters and photopic filters. Specifically, each of the exemplary color filters and photopic filters has an average out-of-band transmission of less than about 0.3% between about 750nm and about 1100nm (i.e., in the IR spectral region). The exemplary color filter and photopic filter (specifically the exemplary red filter) also provide improved UV blocking relative to some conventional metal dielectric color filters, which reduces noise due to UV leakage. Specifically, each of the exemplary color filters and photopic filters has an average out-of-band transmission of less than about 2% between about 300nm and about 400nm (i.e., in the near UV spectral region).

The color gamut 680 of the exemplary RGB filter set is plotted in the CIE xy chromaticity diagram in fig. 6A, along with the color gamut 681 of the conventional dye-based RGB filter set for comparison. Beneficially, the color gamut 680 of the exemplary RGB filter set is much larger than the color gamut 681 of the conventional dye-based RGB filter set.

The color locus 682 of the exemplary red filter at 0 ° to 60 ° of incidence is plotted in the CIE xy chromaticity diagram in fig. 6B along with the color locus 683 of a conventional all-dielectric red filter at 0 ° to 60 ° of incidence. The color locus 684 of the exemplary photopic filter at angles of incidence of 0 ° to 60 ° is plotted in the CIE xy chromaticity diagram in fig. 6C. Beneficially, the angular offset of the exemplary red filter and photopic vision filter is much smaller than the angular offset of the conventional all-dielectric red filter and photopic vision filter.

In some embodiments, the filter is a UV filter having a relatively narrow passband in the UV spectral region (e.g., between about 180nm and about 420 nm). For example, the filter may be an ultraviolet a (uva) or ultraviolet b (uvb) filter. In such embodiments, the filter typically has a maximum in-band transmission of greater than about 5%, and preferably greater than about 15%, and an average out-of-band transmission between about 420nm and about 1100nm (i.e., in the visible and IR spectral regions) of less than about 0.3%. In contrast, fully conventional dielectric UV filters are typically not inherently IR blocking. Typically, in such embodiments, the filter also has a low angular shift, i.e., a shift in the center wavelength as the angle of incidence changes from 0 °. Typically, the filter has an angular offset of less than about 5% at an angle of incidence of 60 °, or an offset of about 15nm in size for a filter centered at 300 nm. In contrast, conventional all-dielectric UV filters are typically very angle sensitive.

The optical design (i.e., number of layers, materials, and thicknesses) of exemplary UVA, UVB, and filters centered at 220nm are summarized in fig. 12. Each of the metal layers is composed of aluminum, and the metal layers have a physical thickness between about 10nm and about 20 nm. Each of the dielectric layers is composed of a high refractive index dielectric material, i.e., Ta for UVA filters₂O₅And HfO for UVB filters and filters with a central wavelength of 220nm₂And the dielectric layer has a physical thickness between about 40nm and about 60 nm. The exemplary UV filter does not include a corrosion-inhibiting layer because the additional protection provided by the corrosion-inhibiting layer is generally not required when the metal layer is comprised of aluminum.

The filter height of the UVA filter is 350nm, the filter height of the UVB filter is 398nm, and the filter height of the filter having a center wavelength of 220nm is 277 nm. These filter heights are much smaller than those of conventional all-dielectric UV filters.

Transmission spectra 1370(0 °) and 1371(60 °) of the exemplary UVA filter at angles of incidence of 0 ° to 60 ° are plotted in fig. 13A, transmission spectra 1372(0 °) and 1373(60 °) of the exemplary UVB filter at angles of incidence of 0 ° to 60 ° are plotted in fig. 13B, and transmission spectra 1374(0 °) and 1375(60 °) of the exemplary filter with a center wavelength of 220nm at angles of incidence of 0 ° to 60 ° are plotted in fig. 13C. The transmission spectrum 1370 of the exemplary UVA filter at 0 ° of incidence includes a UVA passband centered at about 355nm, the transmission spectrum 1372 of the exemplary UVB filter at 0 ° of incidence includes a UVB passband centered at about 295nm, and the transmission spectrum 1374 of the filter at 0 ° of incidence with a center wavelength of 220nm includes a passband centered at about 220 nm. The angular offset of the exemplary UV filter at an angle of incidence of 60 ° is less than about 15nm in magnitude. Beneficially, the angular offset of the exemplary UV filter is much smaller compared to the angular offset of a conventional all-dielectric UV filter.

Each of the exemplary UV filters has a maximum in-band transmission of greater than about 10%. Specifically, the UVA filter and the UVB filter each have a maximum in-band transmittance of greater than about 20%. Beneficially, the exemplary UV filter provides improved IR blocking relative to conventional all-dielectric UV filters, which reduces noise due to IR leakage. Specifically, each of the exemplary UV filters has an average out-of-band transmission of less than about 0.3% between about 420nm and about 1100nm (i.e., in the visible and IR spectral regions).

The optical filter of the present invention is particularly useful when included as part of a sensor device or other active device. The sensor device may be any type of sensor device comprising one or more sensor elements in addition to one or more optical filters according to the invention. In some instances, the sensor device may also include one or more conventional optical filters. For example, the sensor device may be an image sensor, an ambient light sensor, a proximity sensor, a color sensor, a UV sensor, or a combination thereof. The one or more sensor elements may be any type of conventional sensor element. Typically, the one or more sensor elements are photodetectors such as photodiodes, charge-coupled device (CCD) sensor elements, Complementary Metal Oxide Semiconductor (CMOS) sensor elements, silicon detectors, or dedicated UV sensitiveA sensor is provided. The one or more sensor elements may be front-illuminated or back-illuminated. The sensor element may be made of any typical sensor material (such as silicon, indium gallium arsenide (In)_1-xGa_xAs), gallium arsenide (GaAs), germanium, lead sulfide (PbS), or gallium nitride (GaN)).

One or more filters are disposed over the one or more sensor elements such that the one or more filters filter light provided to the one or more sensor elements. Typically, one filter is provided on each sensor element. In other words, each pixel of the sensor device typically comprises one filter and one sensor element. Preferably, the one or more optical filters are arranged directly on the one or more sensor elements, e.g. on a passivation layer of the one or more sensor elements. For example, one or more filters may be formed on one or more sensor elements by a lift-off process. However, in some examples, one or more coatings may be disposed between the one or more filters and the one or more sensor elements. In some instances, one or more filters may be integrated with one or more sensor elements.

In some embodiments, the sensor device comprises a single sensor element and a single optical filter according to the invention arranged on the sensor element. Referring to fig. 7, a first embodiment of a sensor device 790 includes a sensor element 711 and an optical filter 700 disposed on the sensor element 711. For example, sensor device 790 may be an ambient light sensor, sensor element 711 may be a photodiode, and filter 700 may be a photopic filter (such as the exemplary photopic filter in fig. 4D) or an IR blocking filter. For another example, sensor device 790 may be a UV sensor, sensor element 711 may be a photodiode, and filter 700 may be a UV filter such as the exemplary UVA, UVB, or a filter centered at 220nm in fig. 12.

In an exemplary embodiment of the ambient light sensor, the photopic vision filter according to the invention is integrated with a photodiode. The photopic vision filter is setOn the photodiode, usually arranged thereon, e.g. of Si₃N₄On the planar passivation layer. An optional protective coating or encapsulation layer (e.g., comprised of epoxy) may be disposed over the photopic filter and the photodiode. The optical design of the photopic vision filter is optimized by taking into account the passivation layer and, if present, the encapsulation layer.

Transmission spectra 1470(0 °) and 1471(60 °) of exemplary photopic filters optimized for integration with photodiodes at incident angles of 0 ° to 60 ° are plotted in fig. 14 along with a normalized photopic response curve 1472. Transmission spectra 1470 and 1471 and Si₃N₄The passivation layer is matched with the epoxy resin packaging layer. The transmission spectrum 1470 of the exemplary photopic filter at an incidence angle of 0 ° includes a photopic pass band centered at about 555 nm. The transmission spectrum 1470 of the exemplary photopic filter fairly well follows the normalized photopic response curve 1472 at incident angles from 0 ° to 40 °. Further, the exemplary photopic filters block UV and IR light at incident angles of 0 ° to 60 ° and have low angular offset. Beneficially, the exemplary photopic vision filter is also environmentally durable, e.g., 96 hours at a temperature of 125 ℃ and 100% relative humidity.

In other embodiments, the sensor device comprises a plurality of sensor elements and a plurality of optical filters according to the invention arranged on the plurality of sensor elements. Typically, the sensor elements are arranged in an array. In other words, the sensor elements form a sensor array, such as a photodiode array, a CCD array, a CMOS array or an array of any other type of conventional sensors. It is also common to arrange the filters 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 (mosaics). For example, the array may be a rectangular array having rows and columns.

Typically in such embodiments, the filters are substantially separate from each other. In other words, the peripheries of the filters do not generally touch each other. However, in some instances, the dielectric layers of the optical filter may inadvertently contact while the metal layers (specifically the chamfered edges) remain separated from each other.

Typically, the plurality of filters includes different types of filters having mutually different pass bands. For example, the plurality of filters may include color filters (such as red, green, blue, cyan, yellow, and/or magenta filters), photopic filters, IR blocking filters, UV filters, or combinations thereof. In some embodiments, the plurality of filters includes different types of color filters that form the CFA. For example, the plurality of filters may include red, green, and blue filters forming an RGB filter array (such as a bayer filter array), such as the exemplary red, green, and blue filters in fig. 4A-4C. For another example, the plurality of filters may include cyan, magenta, or yellow filters forming a CMY filter array.

Advantageously, different types of filters may have different numbers of metal layers and/or different thicknesses of metal layers from each other. In some embodiments, at least two of the different types of filters include different numbers of metal layers from each other. In the same or other embodiments, at least two of the different types of filters have mutually different metal layer thicknesses. For example, the exemplary blue filter in fig. 4C has a different number of metal layers than the exemplary red and green filters in fig. 4A and 4B. In addition, all of the exemplary red, green, and blue color filters in fig. 4A through 4C have different metal layer thicknesses from each other.

Referring to fig. 8, a second embodiment of a sensor device 890 includes a plurality of sensor elements 811 and a plurality of filters 800 and 804 disposed over the plurality of sensor elements 811. The plurality of optical filters 800 and 804 includes a first type of optical filter 800 having a first passband and a second type of optical filter 804 having a second passband different from the first passband. For example, sensor device 890 may be an image sensor, plurality of sensor elements 811 may form a CCD array, and plurality of filters 800 and 804 may form a bayer filter array, only a portion of a row of which is shown. The first type of filter 800 may be a green filter (such as the exemplary green filter in fig. 4B) and the second type of filter 804 may be a red filter (such as the exemplary red filter in fig. 4A) or a blue filter (such as the exemplary blue filter in fig. 4C).

Any of the embodiments of the sensor device described so far may be combined with one or more additional filters and one or more additional sensor elements that are more environmentally durable.

Thus, in some embodiments, the sensor device comprises, in addition to the one or more first optical filters arranged on the one or more first sensor elements according to the invention, one or more second optical filters arranged on the one or more second sensor elements. The one or more second filters are more environmentally durable than the one or more first filters. For example, the one or more first filters may be silver-dielectric filters according to the present invention, wherein the metal layer is composed of silver or a silver alloy. The second one or more second filters may be aluminum-dielectric filters according to the present invention, wherein the metal layer is composed of aluminum. Alternatively, the one or more second filters may be conventional filters, such as all-dielectric, silicon-dielectric, or hydrogenated silicon-dielectric filters.

In such embodiments, the one or more second filters partially overlap the one or more first filters such that the environmentally more durable one or more second filters protectively cover the environmentally less durable periphery of the one or more first filters. Advantageously, this overlapping arrangement provides additional protection for the one or more first filters (in particular the chamfered edges of the metal layers) from environmental deterioration, such as corrosion. Due to the small slopes of the filter sides and the small filter layer height of the one or more first filters, the one or more second filters conform when deposited on the substrate and on the sloped sides at the periphery of the one or more first filters, which provides a continuous layer in the one or more second filters.

The one or more second filters extend on the slanted sides (including the chamfered edges of the metal layer) at the periphery of the one or more first filters, preferably along the entire periphery of the one or more first filters. Preferably, the one or more second filters completely cover the slanted sides at the periphery of the one or more first filters. However, the one or more second filters do not cover or obscure the one or more first sensor elements.

Typically, the one or more first filters and the one or more second filters have mutually different pass bands. For example, the one or more first filters may be color filters (such as red, green, blue, cyan, yellow, or magenta filters), photopic filters, IR blocking filters, or a combination thereof. In particular, the one or more first filters may be silver-dielectric color filters (such as the exemplary red, green, and/or blue filters in fig. 4A-4C), silver-dielectric photopic filters (such as the exemplary photopic filters in fig. 4D), or IR blocking filters.

The one or more second filters may be, for example, UV filters or near IR filters or a combination thereof. In particular, the one or more second filters may be aluminum-dielectric UV filters (such as the exemplary UVA, UVB, and/or 220nm centered filters in fig. 12) or all-dielectric UV filters. Alternatively, the one or more second filters may be silicon-dielectric or hydrogenated silicon-dielectric near-IR filters, such as the filters described in U.S. patent application publication No.2014/0014838 to Hendrix et al, published on 16/1/2014.

Generally, in such embodiments, the sensor device is multifunctional and incorporates different types of optical sensors having different functions, determined primarily by the pass bands of the one or more first filters and the one or more second filters. The one or more first optical filters and the one or more first sensor elements form a first type of optical sensor, and the one or more second optical filters and the one or more second sensor elements form a second type of optical sensor. For example, the first type of optical sensor may be an ambient light sensor comprising a photopic filter or an IR blocking filter, a color sensor comprising one or more different types of color filters, or an image sensor comprising a plurality of different types of color filters. The second type of optical sensor may for example be a UV sensor comprising a UV filter or a proximity sensor comprising a near IR filter.

Referring to fig. 15A, a third embodiment of a sensor device 1590 comprises a first sensor element 1511 and a first optical filter 1500 according to the invention arranged on the first sensor element 1511, forming a first type of optical sensor. The sensor device 1590 further comprises a second sensor element 1512 and an environmentally more durable second filter 1505 disposed over the second sensor element 1512 forming a second type of optical sensor.

For example, the first type of optical sensor may be an ambient light sensor, and the first optical filter 1500 may be a silver-dielectric photopic filter (such as the exemplary photopic filter in fig. 4D) or a silver-dielectric IR blocking filter. The second type of optical sensor may be, for example, a UV sensor, and second filter 1505 may be an aluminum-dielectric UV filter (such as the exemplary UVA, UVB, or filter with a center wavelength of 220nm in fig. 12) or an all-dielectric UV filter. Alternatively, the second type of optical sensor may be a proximity sensor, and second filter 1505 may be a near-IR filter, such as an all-dielectric, silicon-dielectric, or hydrogenated silicon-dielectric near-IR filter. The first sensor element 1511 and the second sensor element 1512 may be photodiodes.

Referring specifically to fig. 15A, the second filter 1505 extends along the entire periphery of the first filter 1500 on the sloped side of the first filter 1500. Thus, second filter 1505 protectively covers the periphery of first filter 1500 including the beveled edges of the metal layer.

Referring specifically to fig. 15B and 15C, the first filter 1500 covers and filters the light provided to the first sensor element 1511. The second filter 1505 covers and filters the light provided to the second sensor element 1512 and surrounds but does not cover the first sensor element 1511. In the layout shown in fig. 15B, the first sensor elements 1511 and the second sensor elements 1512 are arranged in rows between the rows of bond pads 1513. In an alternative arrangement shown in fig. 15C, the second sensor element 1512 is annular and surrounds the first sensor element 1511.

Referring to FIG. 16, a fourth embodiment of a sensor device 1690 includes a plurality of first sensor elements 1611 and a plurality of first filters 1600, 1604, and 1606 arranged according to the invention on the plurality of first sensor elements 1611, which form a first type of optical sensor. Sensor device 1690 also includes a second sensor element 1612 and a second optical filter 1605 disposed on second sensor element 1612, forming a second type of optical sensor.

For example, the first type of optical sensor may be an image sensor or a color sensor, and the plurality of first filters 1600, 1604, and 1606 may be different types of color filters, such as the exemplary silver-dielectric red, green, and blue filters in fig. 4A through 4C. The second type of optical sensor may be, for example, a UV sensor, and the second filter 1605 may be a UV filter, such as the exemplary aluminum-dielectric UVA, UVB, or a filter with a center wavelength of 220nm in fig. 12. Alternatively, the second type of optical sensor may be a proximity sensor and the second filter 1605 may be a near-IR filter, such as an all dielectric, silicon-dielectric, or hydrogenated silicon-dielectric near-IR filter. The plurality of first and second sensor elements 1611, 1612 may form a photodiode array.

Claims (20)

1. A sensor apparatus, comprising:

a first sensor element;

a first filter disposed on the first sensor element;

a second sensor element; and

a second filter disposed on the second sensor element,

the second filter extends on the inclined side of the first filter in a manner that protectively covers the periphery of the first filter.

2. The sensor apparatus of claim 1, wherein the second filter is more environmentally durable than the first filter.

3. The sensor device of claim 1, wherein the second filter also extends on different sloped sides of the first filter.

4. The sensor device of claim 1, wherein the sensor device is a single-chip microprocessor,

wherein the first sensor element and the first filter form an optical sensor of a first type, an

Wherein the second sensor element and the second filter form a second type of optical sensor.

5. The sensor device of claim 1, wherein the first sensor element and the first filter form an ambient light sensor.

6. The sensor device of claim 1, wherein the first filter is a silver-dielectric photopic filter or a silver-dielectric Infrared (IR) blocking filter.

7. The sensor device of claim 1, wherein the second sensor element and the second filter form an Ultraviolet (UV) sensor.

8. The sensor device of claim 1, wherein the second filter is an aluminum-dielectric Ultraviolet (UV) filter, a filter with a center wavelength of 220nm, or an all-dielectric filter.

9. The sensor device of claim 1, wherein the second sensor element and the second filter form a proximity sensor.

10. The sensor device of claim 1, wherein the second filter is a near Infrared (IR) filter.

11. The sensor device of claim 1, wherein the first sensor element and the second sensor element are photodiodes.

12. The sensor device of claim 1, wherein a periphery of the first filter comprises a chamfered edge of the metal layer.

13. A sensor apparatus, comprising:

a first sensor element;

a first filter covering the first sensor element;

a second sensor element; and

a second filter covering the second sensor element and surrounding the first sensor element.

14. The sensor device of claim 13, wherein the second filter does not cover the first sensor element.

15. The sensor device of claim 13, wherein the sensor device is,

wherein the first filter filters light provided to the first sensor element, an

Wherein the second filter filters light provided to the second sensor element.

16. The sensor device of claim 13, further comprising:

a first row of bond pads; and

a second row of bond pads.

17. The sensor device of claim 16, wherein the first and second sensor elements are disposed between the first and second rows of bond pads.

18. The sensor device of claim 13, wherein the second sensor element is annular.

19. The sensor device of claim 13, wherein the second sensor element surrounds the first sensor element.

20. A sensor apparatus, comprising:

a plurality of first sensor elements;

a plurality of first filters for the first light,

the plurality of first sensor elements and the plurality of first filters form a first type of optical sensor; a second sensor element; and

a second filter disposed on the second sensor element,

the second sensor element and the second filter form a second type of optical sensor.