JP2022038288A - Manufacturing method of solid state imaging device filter and manufacturing method of solid state imaging device - Google Patents

Abstract

To provide a manufacturing method of a solid state imaging device filter and a manufacturing method of a solid state imaging device, capable of preventing a functional deterioration caused by a partial elution of an infrared light absorption pigment included in an infrared light cut filter.SOLUTION: A manufacturing method of a solid state imaging device filter 10F includes: a step of forming at least one color filter from among color filters 12R,12G and 12B of red, green and blue, respectively, and an infrared light pass filter 12P, on a semiconductor substrate; a step of forming an infrared light cut precursor layer on the semiconductor substrate with the at least one color filter from among the respective color filters 12R,12G and 12B of red, green and blue and the infrared light pass filter 12P formed thereon; and a step of dry-etching the infrared light cut precursor layer to form an infrared light cut filter 14 on the color filters 12R, 12G, and 12B.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for manufacturing a filter for a solid-state image sensor and a method for manufacturing a solid-state image sensor.

A solid-state image sensor such as a CMOS image sensor or a CCD image sensor includes a photoelectric conversion element that converts light intensity into an electric signal. The solid-state image sensor can detect light corresponding to a plurality of colors, for example. Some solid-state image pickup devices include a color filter for each color and a photoelectric conversion element for each color, and the photoelectric conversion element for each color detects light for each color (see, for example, Patent Document 1). In addition, the solid-state image pickup device includes an organic photoelectric conversion element and an inorganic photoelectric conversion element, and detects light of each color by each photoelectric conversion element without using a color filter (see, for example, Patent Document 2). ).

Some solid-state image sensors are provided with an infrared light cut filter on a photoelectric conversion element. In this type of solid-state image sensor, the infrared light absorbing dye of the infrared light cut filter absorbs infrared light, thereby cutting the infrared light that can be detected by each photoelectric conversion element with respect to the photoelectric conversion element. .. As a result, the detection accuracy of visible light in each photoelectric conversion element is improved. Some infrared light cut filters contain, for example, a cyanine dye which is an infrared light absorbing dye (see, for example, Patent Document 3).

Japanese Patent Application Laid-Open No. 2003-060176 Japanese Unexamined Patent Publication No. 2018-060910 Japanese Unexamined Patent Publication No. 2007-219114

By the way, with the miniaturization of the pixel size in the solid-state image sensor, the miniaturization of the infrared light cut filter is required. Miniaturization of the infrared light cut filter is realized by dry etching using a resist pattern formed on the infrared light cut filter. In the patterning of the infrared light cut filter using dry etching, first, a resist pattern is formed on the infrared light cut filter. Then, the infrared light cut filter is etched using the resist pattern, and then the resist pattern is peeled off from the infrared light cut filter. The stripping solution used to strip the resist pattern from the infrared light cut filter cuts part of the infrared light absorbing dye contained in the infrared light cut filter by contacting the infrared light cut filter. It may elute to the outside of the filter. This may reduce the function of the solid-state image sensor.

The present invention provides a method for manufacturing a filter for a solid-state image sensor capable of suppressing functional deterioration caused by partial elution of an infrared light absorbing dye contained in an infrared light cut filter, and a method for manufacturing a solid-state image sensor. The purpose is.

One aspect of the method for manufacturing a filter for a solid-state imaging device for solving the above problems is to use a color filter of at least one color among the red (R), green (G), and blue (B) color filters. A step of forming an infrared light path filter on a semiconductor substrate, a color filter of at least one color among the red (R), green (G), and blue (B) color filters, and infrared light. An infrared light cut filter is formed on the color filter by a step of forming an infrared light cut precursor layer on the semiconductor substrate on which the pass filter is formed and by dry etching the infrared light cut precursor layer. Including the process.

Further, in the step of forming the infrared light cut precursor layer, at least one color filter among the red (R), green (G), and blue (B) color filters and an infrared light path are used. The infrared light cut precursor layer is formed on the semiconductor substrate on which the filter is formed so as to cover the surfaces of the color filter and the infrared light path filter, and the infrared light cut filter is formed. In the step, the infrared light cut precursor layer is dry-etched to form the infrared light cut filter so as to cover the surface of the color filter while exposing the surface of the infrared light pass filter. May be good.

Further, the infrared light path filter has a thicker film thickness than the red (R), green (G), and blue (B) color filters, and the red (R), green (G), and so on. Among the blue (B) color filters, the height difference from the uppermost color filter is within the range of 0.5 μm or more and 1.0 μm or less, and the dry etching amount of the infrared light cut precursor layer is 1. It may be 0.0 μm or less.

Further, among the red (R), green (G), and blue (B) color filters, the thickness of the uppermost color filter is within the range of 0.5 μm or more and 1.0 μm or less. The thickness of the infrared light cut precursor layer may be in the range of 0.5 μm or more and 1.1 μm or less.

Further, before forming the infrared light cut precursor layer, on the surface of the infrared light path filter and on the surface of each of the red (R), green (G), and blue (B) color filters. , A step of forming an etching stopper layer made of polysiloxane, and the like may be further included.

Further, a step of forming an oxygen blocking layer covering the surface of the infrared light cut filter and the surface of the infrared light pass filter, and a step of forming a plurality of microlenses on the oxygen blocking layer are further performed. It may be included.

Further, a step of forming a plurality of microlenses on a surface including the surface of the infrared light cut filter and the surface of the infrared light pass filter, and an oxygen blocking layer covering the surfaces of the plurality of microlenses are provided. It may further include a step of forming.

Further, one aspect of the method for manufacturing a solid-state image sensor for solving the above problems is a step of preparing a semiconductor substrate and a filter for a solid-state image sensor on the semiconductor substrate by the above-mentioned method of manufacturing a filter for a solid-state image sensor. And the steps of forming.

According to the present invention, it is possible to suppress the functional deterioration of the solid-state image sensor due to the partial elution of the infrared light absorbing dye contained in the infrared light cut filter.

It is an exploded perspective view which shows the structure of the solid-state image sensor which concerns on embodiment of this invention. It is a process drawing for demonstrating the manufacturing method of the solid-state image sensor which concerns on embodiment of this invention. It is a process drawing for demonstrating the manufacturing method of the solid-state image sensor which concerns on embodiment of this invention. It is a process drawing for demonstrating the manufacturing method of the solid-state image sensor which concerns on embodiment of this invention. It is a process drawing for demonstrating the manufacturing method of the solid-state image sensor which concerns on embodiment of this invention. It is a process drawing for demonstrating the manufacturing method of the solid-state image sensor which concerns on embodiment of this invention. It is a process drawing for demonstrating the manufacturing method of the solid-state image sensor which concerns on embodiment of this invention. It is a process drawing for demonstrating the manufacturing method of the solid-state image sensor which concerns on the modification of embodiment of this invention. It is a process drawing for demonstrating the manufacturing method of the solid-state image sensor which concerns on the modification of embodiment of this invention. It is a process drawing for demonstrating the manufacturing method of the solid-state image sensor which concerns on the modification of embodiment of this invention.

An embodiment of a method for manufacturing a filter for a solid-state image sensor and a method for manufacturing a solid-state image sensor according to the present invention will be described with reference to FIGS. 1 to 10. Hereinafter, the structure of the solid-state image sensor and the method of manufacturing the solid-state image sensor will be described in order. In the present embodiment, the infrared light is light having a wavelength included in the range of 0.7 μm or more and 1 mm or less, and the near infrared light is particularly in the range of 700 nm or more and 1100 nm or less among the infrared light. It is light having a wavelength contained in.

[Solid image sensor]
The structure of the solid-state image pickup device according to the present embodiment will be described with reference to FIG. FIG. 1 is a schematic configuration diagram (disassembled perspective view) showing each layer of a part of a solid-state image sensor separated.

As shown in FIG. 1, the solid-state image sensor 10 includes a filter 10F for a solid-state image sensor and a plurality of photoelectric conversion elements 11.
The plurality of photoelectric conversion elements 11 include a red photoelectric conversion element 11R, a green photoelectric conversion element 11G, a blue photoelectric conversion element 11B, and an infrared light photoelectric conversion element 11P.

The solid-state image pickup device 10 includes a plurality of red photoelectric conversion elements 11R, a plurality of green photoelectric conversion elements 11G, a plurality of blue photoelectric conversion elements 11B, and a plurality of infrared light photoelectric conversion elements 11P. The plurality of infrared light photoelectric conversion elements 11P measure the intensity of infrared light. Note that FIG. 1 shows the repeating unit of the photoelectric conversion element 11 in the solid-state image sensor 10 for convenience of illustration.

The solid-state image sensor filter 10F includes a plurality of visible light filters, an infrared light path filter 12P, an etching stopper layer 13, an infrared light cut filter 14, an oxygen blocking layer 15, a plurality of visible light microlenses, and red. A microlens 16P for external light is provided.

The visible light color filter is composed of a red filter 12R, a green filter 12G, and a blue filter 12B. The red filter 12R is located on the incident side of light with respect to the red photoelectric conversion element 11R. The green filter 12G is located on the incident side of light with respect to the green photoelectric conversion element 11G. The blue filter 12B is located on the incident side of light with respect to the blue photoelectric conversion element 11B.

The infrared light path filter 12P is located on the incident side of the light with respect to the infrared light photoelectric conversion element 11P. The infrared light path filter 12P cuts visible light that can be detected by the infrared light photoelectric conversion element 11P with respect to the infrared light photoelectric conversion element 11P. As a result, the detection accuracy of infrared light by the infrared light photoelectric conversion element 11P is improved. The infrared light that can be detected by the infrared light photoelectric conversion element 11P is, for example, near-infrared light.

The etching stopper layer 13 is located on the incident side of light with respect to the respective color filters (color filters) 12R, 12G, 12B, and the infrared optical pass filter 12P. More specifically, when viewed from the viewpoint facing the plane on which the etching stopper layer 13 spreads, the etching stopper layer 13 is placed on the red filter 12R, the green filter 12G, the blue filter 12B, and the infrared light path filter 12P. To position.

The infrared light cut filter 14 is located on the incident side of the light with respect to the etching stopper layer 13. The infrared light cut filter 14 includes a through hole 14H. The infrared light pass filter 12P is located in the region defined by the through hole 14H when viewed from the viewpoint facing the plane on which the infrared light cut filter 14 spreads. On the other hand, when viewed from the viewpoint facing the plane on which the infrared light cut filter 14 spreads, the infrared light cut filter 14 is on the red filter 12R, the green filter 12G, the blue filter 12B, and the etching stopper layer 13. Located in.

The oxygen blocking layer 15 is located on the incident side of the light with respect to the infrared light cut filter 14. The oxygen blocking layer 15 is a layer common to the red filter 12R, the green filter 12G, the blue filter 12B, and the infrared optical pass filter 12P. The oxygen blocking layer 15 suppresses the transmission of the oxidation source toward the infrared light cut filter 14. Oxidation sources are, for example, oxygen and water.

The oxygen permeability of the oxygen blocking layer 15 is preferably 5.0 cc / m ² / day / atom or less, for example. This oxygen permeability is a value measured by a method according to JIS K7126: 2006. When the oxygen permeability of the oxygen blocking layer 15 is 5.0 cc / m ² / day / atom or less, the oxygen blocking layer 15 suppresses the arrival of the oxidation source at the infrared light cut filter 14. Therefore, the infrared light cut filter 14 is less likely to be oxidized by the oxidation source. This makes it possible to improve the light resistance of the infrared light cut filter 14.

The microlens is composed of a red microlens 16R, a green microlens 16G, a blue microlens 16B, and an infrared light microlens 16P. The red microlens 16R is located on the incident side of the light with respect to the red filter 12R. The green microlens 16G is located on the incident side of the light with respect to the green filter 12G. The blue microlens 16B is located on the incident side of the light with respect to the blue filter 12B. The infrared light microlens 16P is located on the incident side of the light with respect to the infrared light path filter 12P.

Each microlens 16R, 16G, 16B, 16P includes an incident surface 16S which is an outer surface. Each of the microlenses 16R, 16G, 16B, 16P has a refractive index difference with the outside air for collecting the light entering the incident surface 16S toward the respective photoelectric conversion elements 11R, 11G, 11B, 11P. Each microlens 16R, 16G, 16B, 16P may be configured to contain a transparent resin.

The thickness (layer thickness) of each of the color filters 12R, 12G, and 12B is thinner than the thickness (layer thickness) of the infrared optical path filter 12P. That is, the height of each color filter 12R, 12G, 12B is lower than the height of the infrared optical path filter 12P. The sum of the thickness of the etching stopper layer 13 and the thickness of the infrared light cut filter 14 corresponds to the difference between the thickness of the filters 12R, 12G, 12B for each color and the thickness of the infrared light pass filter 12P. As described above, the thickness of the infrared pass filter 12P is larger (thicker) than the thickness of the filters 12R, 12G, and 12B for each color. On the other hand, the step TP (see FIG. 2) between the infrared light path filter 12P and the filters 12R, 12G, 12B for each color is filled with the etching stopper layer 13 and the infrared light cut filter 14. Therefore, it is easy to obtain flatness in the lower layer of the microlenses 16R, 16G, 16B for each color and the microlens 16P for infrared light. The step TP is preferably in the range of 0.5 μm or more and 1.0 μm or less. If the step TP exceeds 1.0 μm, the flatness in the lower layer of the infrared light microlens 16P cannot be obtained, and the heights of the microlenses 16R, 16G, 16B for each color become non-uniform in the wafer surface, and solid-state imaging is performed. The possibility of causing functional deterioration of the element 10 increases. If the step TP is less than 0.5 μm, the performance of the infrared light cut filter 14 cannot be fully exhibited.

[Manufacturing method of solid-state image sensor]
A method for manufacturing a solid-state image sensor including a filter for a solid-state image sensor will be described with reference to FIGS. 2 to 10.

The method for manufacturing a filter for a solid-state image sensor according to the present embodiment includes a step of forming a color filter and an infrared light path filter, a step of forming an etching stopper layer, a step of forming an infrared light cut precursor layer, and red. It includes at least a step of forming an external light cut filter. In the step of forming the color filter and the infrared light pass filter, the color filter and the infrared light pass filter are formed on the semiconductor substrate. In the step of forming the etching stopper layer, the etching stopper layer is formed on the semiconductor substrate on which the color filter and the infrared light pass filter are formed. In the step of forming the infrared light cut precursor layer, an infrared light cut precursor layer having an etching rate different from that of the etching stopper layer in dry etching is formed on the etching stopper layer. In the step of forming the infrared light cut filter, the infrared light cut precursor layer is dry-etched to form the infrared light cut filter.

Hereinafter, a method for manufacturing a filter for a solid-state image sensor and a method for manufacturing a solid-state image sensor according to the present embodiment will be described in more detail with reference to the drawings. 2 to 10 schematically show a cross section when the solid-state image sensor is cut along the direction in which the layers constituting the solid-state image sensor are laminated.

As shown in FIG. 2, in the method for manufacturing a filter for a solid-state image sensor according to the present embodiment, first, a semiconductor substrate 21 is prepared. A plurality of photoelectric conversion elements 11 are two-dimensionally arranged on the semiconductor substrate 21 so that one photoelectric conversion element 11 corresponds to one pixel. In addition, in FIGS. 2 to 10, two blue photoelectric conversion elements 11B and three infrared light photoelectric conversion elements 11P are shown. The material forming the semiconductor substrate 21 may be, for example, an oxide such as Si and SiO ₂ , a nitride such as SiN, or a mixture thereof.

As shown in FIG. 2, in the semiconductor substrate 21, the blue filter 12B is formed at the position corresponding to the blue photoelectric conversion element 11B of the semiconductor substrate 21, and the position corresponding to the infrared light photoelectric conversion element 11P. Infrared light path filter 12P is formed. At this time, the thickness of the infrared light pass filter 12P is formed to be thicker than the thickness of the blue filter 12B. The step between the surface of the infrared light path filter 12P and the surface of the blue filter 12B formed in this way is represented as "step TP" in FIG.

In FIG. 2, the red filter 12R, the green photoelectric conversion element 11G, and the green photoelectric conversion element 11G are located at the positions corresponding to the red photoelectric conversion element 11R and the red photoelectric conversion element 11R. Each description of the green filter 12G is omitted.

The blue filter 12B is formed, for example, by forming a coating film containing a blue photosensitive resin and patterning the coating film using a photolithography method. The coating film containing the blue photosensitive resin is formed, for example, by applying a coating liquid containing the blue photosensitive resin and drying the coating film. The blue filter 12B is formed, for example, by exposing and developing a coating film containing a blue photosensitive resin, which corresponds to a region of the blue filter 12B.

The infrared light pass filter 12P is formed, for example, by forming a coating film containing a colored photosensitive resin and patterning the coating film using a photolithography method. The coating film containing the colored photosensitive resin is formed, for example, by applying a coating liquid containing a photosensitive resin for infrared light and drying the coating film.

The green filter 12G and the red filter 12R are formed on the semiconductor substrate 21 by the same method as the blue filter 12B.
The film thicknesses of the blue filter 12B, the green filter 12G, and the red filter 12R are preferably formed within the range of 0.5 μm or more and 1.0 μm or less in order to secure the desired spectroscopy.

The photosensitive resin for infrared light includes a black dye or a black dye and a photosensitive resin. The black dye is a single dye having a black color, or a mixture having a black color due to two or more kinds of dyes. The black dye may be, for example, an azo dye, an anthraquinone dye, azine dye, quinoline dye, perinone dye, perylene dye, methine dye or the like. The transparent resin which is a photosensitive resin is, for example, an acrylic resin, a polyamide resin, a polyimide resin, a polyurethane resin, a polyester resin, a polyether resin, a polyolefin resin, a polycarbonate resin, a polystyrene resin, and a transparent resin. It may be a norbornene-based resin.

The material forming the infrared light pass filter 12P can contain particles of an inorganic oxide for adjusting the refractive index. The inorganic oxide is, for example, aluminum oxide, silicon oxide, zirconium oxide, and titanium oxide. The infrared optical pass filter 12P can contain additives for having other functions such as a light stabilizer, an antioxidant, a heat stabilizer, and an antistatic agent.

The filter for each color including the blue filter 12B may be formed before the infrared light pass filter 12P, or the infrared light pass filter 12P may be formed before the filter for each color. Since the thickness of the infrared light pass filter 12P is formed to be thicker than the thickness of the filter for each color, it is preferable to form the filter for each color before the infrared light pass filter 12P from the viewpoint of manufacturing.

In the present embodiment, the film thicknesses (each height) of the green filter 12G, the red filter 12R, and the blue filter 12B may be different from each other or may be the same. Here, when the film thicknesses (each height) of the green filter 12G, the red filter 12R, and the blue filter 12B are different from each other, the filter having the thickest film thickness (highest) is the "highest". It is defined as "upper surface color filter". If the green filter 12G, the red filter 12R, and the blue filter 12B have the same film thickness (each height), each color filter is defined as the "top color filter". do.
In the present embodiment, the blue filter 12B shown in FIG. 2 will be described below as a “top color filter”.

As shown in FIG. 3, the etching stopper layer 13 is formed on the semiconductor substrate 21 on which the blue filter 12B and the infrared light pass filter 12P are formed. When forming the etching stopper layer 13, first, a coating liquid is prepared using a resin containing silicon. The resin containing silicon may be, for example, polysiloxane. Polysiloxane is formed from a repeating structure of siloxane bonds. The polysiloxane may be silicone. Silicone is a polysiloxane and contains organic groups such as alkyl and aryl groups.

Next, the above-mentioned coating liquid is applied onto the semiconductor substrate 21 on which the blue filter 12B and the infrared light pass filter 12P are formed, and the coating film is dried. Then, the dried coating film is cured by heating. As a result, the etching stopper layer 13 is formed on the filters 12R, 12G, 12B for each color and on the infrared light path filter 12P.

Next, as shown in FIG. 4, an infrared light cut precursor layer 24 is formed on the etching stopper layer 13. When forming the infrared light cut precursor layer 24, first, a coating liquid containing an infrared light absorbing dye, a transparent resin, and an organic solvent is applied onto the etching stopper layer 13 to dry the coating film. The dried coating is then cured by heating. As a result, the infrared light cut precursor layer 24 is formed on the etching stopper layer 13.

The infrared light absorbing dye for forming the infrared light cut precursor layer 24 is, for example, an anthraquinone dye, a cyanine dye, a phthalocyanine dye, a dithiol dye, a diimonium dye, a squarylium dye, and a croconium dye. It may be at least one selected from the above. The infrared light absorbing dye is preferably at least one of these dyes, a cyanine-based dye and a phthalocyanine-based dye.

The transparent resin for forming the infrared light cut precursor layer 24 is, for example, an acrylic resin, a polyamide resin, a polyimide resin, a polyurethane resin, a polyester resin, a polyether resin, a polyolefin resin, or a polycarbonate resin. , And at least one selected from a polystyrene-based resin and a norbornene-based resin. Of these resins, the transparent resin is preferably an acrylic resin. By using acrylic resin, a flattened and uniform infrared light cut precursor layer is not affected by the step TP between the infrared light pass filter 12P and the filters 12R, 12G, 12B for each color. 24 can be formed.

Next, as shown in FIG. 5, the infrared light cut filter 14 is formed by dry etching over the entire etching surface of the semiconductor substrate 21 having the infrared light cut precursor layer 24. The etching stopper layer 13 formed in the above-mentioned step functions as an etching stopper in this dry etching. The film thickness of the infrared light cut filter 14 is preferably in the range of 0.5 μm or more and 1.0 μm or less in order to exhibit the infrared light cut function of the infrared light cut filter 14, and is preferably 0.8 μm or more. It is more preferably in the range of 1.0 μm or less. If the film thickness of the infrared light cut filter 14 is less than 0.5 μm, the infrared light cut filter function cannot be fully exhibited. When the thickness of the infrared light cut filter 14 exceeds 1.0 μm (for example, when the thickness of the infrared light cut filter 14 is 1.01 μm), the flatness in the lower layer of the infrared light microlens 16P becomes low. Therefore, the heights of the microlenses 16R, 16G, and 16B for each color become non-uniform in the wafer surface, which increases the possibility of causing functional deterioration of the solid-state image sensor 10.

The dry etching of the infrared light cut precursor layer 24 may be, for example, plasma etching. In this dry etching, it is possible to use a reactive gas and a rare gas as the etching gas. The reactive gas may be, for example, oxygen gas. Further, the noble gas may be, for example, argon gas. In the dry etching of the infrared light cut precursor layer 24, it is possible to apply a bias to the infrared light cut precursor layer 24.

Here, the dry etching amount ET (see FIG. 4) of the infrared light cut precursor layer 24 is determined from the thickness of the infrared light cut precursor layer 24 (for example, within the range of 0.5 μm or more and 1.1 μm or less). It corresponds to the thickness obtained by subtracting the step TP between the infrared light path filter 12P and the filters 12R, 12G, 12B for each color. The upper limit of the dry etching amount ET of the infrared light cut precursor layer 24 is 1.0 μm. If the dry etching amount ET of the infrared light cut precursor layer 24 is larger than this, an altered layer may be formed on the etching surface by etching, and the unevenness of the etching surface may become large. As a result, the flatness in the wafer surface may not be ensured.

The etching rate of the etching stopper layer 13 is different from the etching rate of the infrared light cut precursor layer 24. Etching rate is the thickness of each layer etched per unit time. The etching rate of the etching stopper layer 13 is preferably lower than the etching rate of the infrared light cut precursor layer 24. As a result, the etching time is reduced because the etchant is less likely to collide with the lower layer of the etching stopper layer 13 as compared with the case where the etching rate of the etching stopper layer 13 is higher than the etching rate of the infrared light cut precursor layer 24. It will be easy to adjust.

Next, as shown in FIG. 6, the oxygen blocking layer 15 covering the surface of the infrared light cut filter 14 and the surface of the infrared light path filter 12P is provided from a viewpoint facing the plane on which the semiconductor substrate 21 spreads. Form. The oxygen blocking layer 15 is formed by film formation using a vapor phase film forming method such as a sputtering method, a CVD method, or an ion plating method, or a liquid phase film forming method such as a coating method. The oxygen blocking layer 15 formed of silicon oxide may be formed, for example, by forming a film by a sputtering method using a target made of silicon oxide. Further, the oxygen blocking layer 15 formed from silicon oxide may be formed, for example, by forming a film by a CVD method using silane and oxygen. Further, the oxygen blocking layer 15 made of silicon oxide may be formed, for example, by applying a coating liquid containing polysilazane, modifying it, and drying the coating film.

Next, as shown in FIG. 7, a plurality of microlenses 16 are formed on the oxygen blocking layer 15. As a result, the solid-state image sensor 10 according to the present embodiment can be obtained. The plurality of microlenses 16 are formed at positions overlapping with the color filters 12R, 12G, 12B, and the infrared optical path filter 12P when viewed from a viewpoint facing the plane on which the oxygen blocking layer 15 spreads. Each microlens 16 is formed, for example, by using an etchback method. In the etchback method, first, a transparent resin layer for forming each microlens 16 is formed on the oxygen blocking layer 15. Next, a resist pattern having a shape (lens shape) in which a plurality of hemispheres are lined up is formed on the transparent resin layer. Then, a plurality of microlenses 16 are formed by transferring the shape (lens shape) of the resist pattern to the transparent resin layer by dry etching of the transparent resin layer provided with the resist pattern.

Thereby, a plurality of solid-state image pickup devices 10 described above with reference to FIG. 1 can be formed on one semiconductor substrate 21.
As described above, according to the method for manufacturing the filter 10F for a solid-state image sensor of the embodiment and the method for manufacturing the solid-state image sensor 10, the effects listed below can be obtained.

(1) The method for manufacturing the solid-state image pickup element filter 10F according to the present embodiment is a color filter of at least one color among the red filter 12R, the green filter 12G, and the blue filter 12B (for example, the blue filter 12B). ) And the process of forming the infrared light path filter 12P on the semiconductor substrate 21, and at least one color filter (for example, for blue) among the red filter 12R, the green filter 12G, and the blue filter 12B. Infrared light is formed by forming the infrared light cut precursor layer 24 on the semiconductor substrate 21 on which the filter 12B) and the infrared light pass filter 12P are formed, and by dry etching the infrared light cut precursor layer 24. It includes a step of forming the cut filter 14.

(2) Further, in the step of forming the infrared light cut precursor layer 24 in the method for manufacturing the filter 10F for a solid image pickup element according to the present embodiment, among the red filter 12R, the green filter 12G, and the blue filter 12B. A color filter (for example, a blue filter 12B) and an infrared light pass filter are placed on a semiconductor substrate 21 on which a color filter of at least one color (for example, a blue filter 12B) and an infrared light path filter 12P are formed. In the step of forming the infrared light cut precursor layer 24 so as to cover each surface of 12P and forming the infrared light cut filter 14, the infrared light path is passed by dry etching the infrared light cut precursor layer 24. The infrared light cut filter 14 may be formed so as to cover the surface of the color filter (for example, the blue filter 12B) while exposing the surface of the filter 12P.

With such a configuration, the infrared light cut precursor layer 24 can be fully etched (dry etched) to form the infrared light cut filter 14 without forming a resist pattern. That is, since the manufacturing method of the filter 10F for a solid-state image sensor according to the present embodiment is a manufacturing method that does not form a resist pattern, peeling of the resist pattern is a factor that deteriorates the spectral characteristics of the infrared light cut filter 14. Do not use liquid. As a result, the functional deterioration of the solid-state image pickup device 10 due to the partial elution of the infrared light absorbing dye contained in the infrared light cut filter 14 can be suppressed.

Further, with such a configuration, since the formation of the infrared light cut filter 14 does not depend on the pixel size, the formation of the infrared light cut filter 14 becomes easy. That is, with the above-described configuration, infrared light cut filters 14 having various pixel sizes can be easily formed.
In addition, in the method for manufacturing a filter for a solid-state image sensor according to the prior art, it is necessary to prepare a resist pattern (mask pattern) for each pixel by using, for example, a photolithography method. In that case, it is difficult to form an infrared light cut filter for various pixel sizes because the size of the resist pattern (mask pattern) has a manufacturing limit.

(3) Further, the method for manufacturing the filter 10F for a solid-state image sensor according to the present embodiment is a step of forming an oxygen blocking layer 15 that covers the surface of the infrared light cut filter 14 and the surface of the infrared light path filter 12P. And a step of forming a plurality of microlenses 16 on the oxygen blocking layer 15 may be further included.
With such a configuration, the oxygen blocking layer 15 suppresses the oxidation source from reaching the infrared pass filter 12P, so that the infrared pass filter 12P is less likely to be oxidized.

(4) Further, in the method for manufacturing the filter 10F for a solid-state imaging element according to the present embodiment, the infrared light path filter 12P is more than the color filters of the red filter 12R, the green filter 12G, and the blue filter 12B. The film thickness is thick, and the height difference from the top color filter (for example, blue filter 12B) among the red filter 12R, green filter 12G, and blue filter 12B is 0.5 μm or more and 1.0 μm. Within the following range, the amount of dry etching of the infrared light cut precursor layer 24 in the step of forming the infrared light cut filter 14 may be 1.0 μm or less.

With such a configuration, the infrared light cut filter 14 can be reliably imparted with the desired infrared light cut performance, and the flatness in the lower layer of the infrared light microlens 16P can be obtained, and the wafer surface can be obtained. Within, the heights of the microlenses 16R, 16G, and 16B for each color become uniform, and deterioration of the function of the solid-state image sensor 10 can be suppressed.
Further, with such a configuration, it is possible to suppress that an altered layer is formed on the etching surface by etching and the unevenness of the etching surface becomes large.

(5) Further, in the method for manufacturing the filter 10F for a solid-state image sensor according to the present embodiment, among the red filter 12R, the green filter 12G, and the blue filter 12B, the uppermost color filter (for example, the blue filter). The thickness of 12B) may be in the range of 0.5 μm or more and 1.0 μm or less, and the thickness of the infrared light cut precursor layer 24 may be in the range of 0.5 μm or more and 1.1 μm or less.
With such a configuration, the desired spectral performance can be reliably imparted to the color filters 12R, 12G, and 12B, and the desired infrared light cut performance can be reliably imparted to the infrared light cut filter 14. Can be done.

(6) Further, in the method for manufacturing the filter 10F for a solid-state image sensor according to the present embodiment, before forming the infrared light cut precursor layer 24, the surface of the infrared light path filter 12P and the red filter 12R are used. A step of forming an etching stopper layer 13 made of polysiloxane on the surface of each color filter of the green filter 12G and the blue filter 12B may be further included.

With such a configuration, even if a part of the infrared light cut precursor layer 24 is removed by overetching the infrared light cut precursor layer 24, the etching stopper layer 13 is formed under the infrared light cut precursor layer 24. Since it is located, the collision of the etchant with the lower layer of the etching stopper layer 13 is suppressed. As a result, deterioration of the function of the solid-state image pickup device 10 due to the change in the surface texture in the lower layer of the infrared light cut precursor layer 24 to be etched can be suppressed.

(7) Further, the method for manufacturing the filter 10F for a solid-state image sensor according to the present embodiment is a step of forming an oxygen blocking layer 15 that covers the surface of the infrared light cut filter 14 and the surface of the infrared light path filter 12P. And a step of forming a plurality of microlenses 16 on the oxygen blocking layer 15 may be further included.

With such a configuration, the oxygen blocking layer 15 suppresses the arrival of the oxidation source at the infrared light cut filter 14 and the infrared light path filter 12P, so that the infrared light cut filter 14 and the infrared light are prevented from reaching the infrared light cut filter 14 and the infrared light path filter 12P. The pass filter 12P is less likely to be oxidized.

(8) Further, in the method of manufacturing the filter 10F for a solid-state image sensor according to the present embodiment, each color filter of the red filter 12R, the green filter 12G, and the blue filter 12B, and a plurality of infrared light path filters 12P On the semiconductor substrate 21 in which the red filter 12R, the green filter 12G, and the blue filter 12B are formed, and a plurality of infrared light path filters 12P are formed. It may include a step of forming the infrared light cut precursor layer 24 and a step of forming the infrared light cut filter 14 by dry etching the infrared light cut precursor layer 24.

(9) Further, in the step of forming the infrared light cut precursor layer 24 in the method for manufacturing the filter 10F for a solid-state image pickup element according to the present embodiment, each of the red filter 12R, the green filter 12G, and the blue filter 12B. Infrared light so as to cover all the surfaces of the color filters 12R, 12G, 12B, and the infrared light pass filter 12P on the semiconductor substrate 21 on which the color filter and the plurality of infrared light pass filters 12P are formed. In the step of forming the cut precursor layer 24 and forming the infrared light cut filter 14, the infrared light cut precursor layer 24 is dry-etched to expose the surfaces of the plurality of infrared light pass filters 12P, and each of them is exposed. The infrared light cut filter 14 may be formed so as to cover all the surfaces of the color filters 12R, 12G, and 12B.

With such a configuration, since the infrared light cut precursor layer 24 is filled between the infrared light pass filters 12P and then dry etching is performed, it is not necessary to form a resist pattern. Therefore, the stripping solution of the resist pattern, which is a factor of deteriorating the spectral characteristics of the infrared light cut filter 14, is not used. As a result, the functional deterioration of the solid-state image pickup device 10 due to the partial elution of the infrared light absorbing dye contained in the infrared light cut filter 14 is surely suppressed.

[Modified example of the embodiment]
The above-described embodiment can be modified and implemented as follows.
[Oxygen blocking layer]
In the above-described embodiment, the case where the oxygen blocking layer 15 is formed between the infrared light cut filter 14, the infrared light path filter 12P, and each microlens 16 has been described, but the present invention describes the case. Not limited. The formation position of the oxygen blocking layer 15 is not limited to between the infrared light cut filter 14, the infrared light path filter 12P, and each microlens 16, but is on the outer surface (incident surface 16S) of each microlens 16. May be.

When forming the solid-state image sensor 10 according to this modification, first, as shown in FIG. 8, first, on the surface including the surface of the infrared light cut filter 14 and the surface of the infrared light pass filter 12P, the solid-state image sensor 10 is formed. A plurality of microlenses 26 are formed. Next, each microlens 26 is formed so as to cover at least one of the filters 12R, 12G, 12B for each color and the infrared light path filter 12P.

Next, as shown in FIG. 9, the oxygen blocking layer 25 is formed so as to cover the surfaces of the plurality of microlenses 26. The oxygen blocking layer 25 may have a function as an antireflection layer.

As described above, in the method for manufacturing the filter 10F for a solid-state image sensor according to the present embodiment, a plurality of microlenses are provided on a surface including the surface of the infrared light cut filter 14 and the surface of the infrared light path filter 12P. 26 may be further included, and a step of forming an oxygen blocking layer 25 covering the surface of the plurality of microlenses 26 may be further included.
With such a configuration, the oxygen blocking layer 25 suppresses the oxidation source from reaching the microlens 26, so that the microlens 26 is less likely to be oxidized.

Further, in the above-described embodiment, the case where the oxygen blocking layer 15 is formed has been described, but the present invention is not limited thereto. The filter 10F for a solid-state image sensor does not have to include the oxygen blocking layer 15. Even in this case, by forming the infrared light cut precursor layer 24 on the etching stopper layer 13 that covers the surface of the semiconductor substrate 21, the effect similar to the effect obtained in the form of forming the oxygen blocking layer 15 can be obtained. It is possible to get.

Further, the layer structure of the oxygen blocking layer 25 may be a single layer structure composed of a single compound, a laminated structure of layers composed of a single compound, or a laminated structure of layers composed of different compounds. But it may be.

Further, the surface of the infrared light cut filter 14 and the surface of the infrared light path filter 12P may have a step in the thickness direction of the semiconductor substrate 21. Specifically, the surface of the infrared light cut filter 14 and the surface of the infrared light pass filter 12P have a step of 5 μm or less, more preferably a step of 3 μm or less, still more preferably, in the thickness direction of the semiconductor substrate 21. May have a step of 1 μm or less. In this case, for example, the oxygen blocking layer 15 formed of SiO ₂ can function as a flattening layer that fills the step formed by the surface of the infrared light cut filter 14 and the surface of the infrared light pass filter 12P. .. The oxygen blocking layer 15 functions as a flattening layer by having a thickness capable of filling a step between the surface of the infrared light cut filter 14 and the surface of the infrared light pass filter 12P. Is possible.

[Etching stopper layer]
The portion of the etching stopper layer 13 formed on the surface of the semiconductor substrate 21 may not be completely removed. Even in this case, since the etching stopper layer 13 is formed of the transparent resin, the light incident on the solid-state image pickup device 10 can be incident on the photoelectric conversion element 11 via the etching stopper layer 13.

Further, in the above-described embodiment, the case where the etching stopper layer 13 is formed has been described, but the present invention is not limited thereto. As shown in FIG. 10, the solid-state image sensor filter 10F does not have to include the etching stopper layer 13. In this case, it is difficult to obtain the effect obtained in the form of forming the etching stopper layer 13, but even in this case, the etching time until the surface of the infrared light pass filter 12P appears is adjusted to the infrared ray. It is possible to form the optical cut filter 14.

[Example]
Hereinafter, an example of manufacturing a solid-state image sensor corresponding to the embodiment will be described. In the manufacturing example described below, a manufacturing example of the solid-state image pickup device in the case where the thickness of the infrared light path filter is thicker than the thickness of the filter for each color and the etching stopper layer is not provided will be described.

A green resist layer obtained by spin-coating a green resist containing a green pigment, a photosensitive curing resin, and a thermosetting resin at a rotation speed of 1000 rpm on a semiconductor substrate in which a plurality of photoelectric conversion elements are two-dimensionally arranged. Formed. For green pigments, C.I. I. PG58 was used. In the green resist, the concentration of the green pigment was set to 70% by mass. Next, the green resist layer was selectively exposed using the green mask, and then the exposed green resist layer was developed to form a green filter pattern. Then, the green filter pattern was cured by heating at 230 ° C. for 6 minutes using a hot plate. As a result, a green filter having a thickness of 600 nm was formed.

Next, a blue resist containing a pigment, a photosensitive curable resin, and a thermosetting resin is spun on the green filter and the portion of the semiconductor substrate that is not covered by the green filter at a rotation speed of 1000 rpm. A coated blue resist layer was formed. Pigments include C.I. I. PB156 and C.I. I. PV23 was used. In the blue resist, the concentration of the blue pigment was set to 50% by mass. Next, a blue resist layer was selectively exposed by photolithography using a blue mask, and then the exposed blue resist layer was developed to form a blue filter pattern. Then, the blue filter pattern was cured by heating at 230 ° C. for 6 minutes using a hot plate. As a result, a blue filter having a thickness of 600 nm was formed. At this time, the blue filter was formed on the surface of the semiconductor substrate at a position different from the position where the green filter was formed.

Next, a red resist containing a pigment, a photosensitive curing resin, and a thermosetting resin is applied at 1000 rpm on the green filter, the blue filter, and the portion of the semiconductor substrate that is not covered by these filters. A spin-coated red resist layer was formed at the number of rotations of. Pigments include C.I. I. PR254 and C.I. I. PY139 was used. In the red resist, the pigment concentration was set to 60% by mass. Next, the red resist layer was selectively exposed using the red mask, and then the exposed red resist layer was developed to form a red filter pattern. Then, the red filter pattern was cured by heating at 230 ° C. for 6 minutes using a hot plate. As a result, a red filter having a thickness of 600 nm was formed. At this time, the red filter was formed on the surface of the semiconductor substrate at a position different from the position where the blue filter and the green filter were formed.

Next, a photosensitive infrared light path resist containing a blue pigment, a purple pigment, and a yellow pigment is applied on the filter for each color and on the portion of the semiconductor substrate that is not covered by the color filter. did. As a result, a resist layer for an infrared light path was formed. For blue pigments, C.I. I. PB15: 6 is used, and C.I. I. PV23 is used, and C.I. I. PY139 was used. In the infrared light pass resist, the pigment concentration was set to 78% by mass.

Next, after selectively exposing the resist layer for infrared light path using the mask for infrared light path, the resist layer for infrared light path after exposure is developed to obtain an infrared light path filter pattern. Formed. Then, the infrared light pass filter pattern was cured by heating at 230 ° C. for 6 minutes using a hot plate. As a result, an infrared light path filter having a thickness of 1300 nm was formed. At this time, the infrared light pass filter was formed on the surface of the semiconductor substrate at a position different from the position where the above-mentioned filters for each color were formed. In the infrared optical path filter, the maximum value of the transmittance for light having a wavelength of 400 nm or more and 650 nm or less is 4.8%, and the maximum value of the transmittance for light having a wavelength of 650 nm or more and 730 nm or less is 8. It was 6%. Further, in the infrared optical pass filter, the minimum value of the transmittance for light having a wavelength of 800 nm or more and 1000 nm or less was 92.1%. The step between the infrared light path filter and the filter for each color was 700 nm.

Next, a coating film was formed by spin-coating a coating liquid containing an infrared light absorbing dye and a thermosetting resin on a filter for each color and an infrared light path filter at a rotation speed of 1000 rpm. .. Then, the coating film was cured by heating at 200 ° C. for 20 minutes using a hot plate. As a result, an infrared light cut precursor layer having a thickness of 1000 nm was formed on the filters for each color and on the infrared light pass filter. In the infrared light cut precursor layer, the transmittance for light having a wavelength near 940 nm was 8%.

Next, the infrared light cut precursor layer was dry etched. At this time, an ICP type dry etching apparatus was used as the dry etching apparatus. As the etching gas, a mixed gas containing argon gas and oxygen gas was used, and by applying a bias to the etching target, anisotropic etching was performed on the infrared light cut precursor layer. The amount of dry etching of the infrared light cut precursor layer was 300 nm. As a result, an infrared light cut filter having a thickness of 700 nm was formed.

Next, an oxygen blocking layer formed from SiO ₂ and having a thickness of 100 nm was formed on the surface of the infrared light cut filter and the surface of the infrared light path filter by using a plasma CVD method.

Next, a plurality of microlenses having a height of 500 nm were formed on the oxygen blocking layer by an etchback method. As a result, the solid-state image sensor according to this embodiment was obtained.
As described above, in the method for manufacturing a solid-state image sensor according to the present embodiment, it is not necessary to form a resist pattern for forming an infrared light cut filter. Therefore, a stripping solution for stripping the resist pattern is also unnecessary. As a result, when the infrared light cut filter was formed, the elution of the infrared light absorbing dye contained in the infrared light cut filter was suppressed, and the functional deterioration of the solid-state image sensor could be suppressed. Specifically, the light receiving sensitivity of the solid-state image sensor according to the present embodiment is compared with the solid-state image sensor manufactured by the method for manufacturing a solid-state image sensor according to the prior art in which a resist pattern is formed for forming an infrared light cut filter. Was improved by 1.2 times to 1,5 times in each pixel (each color).

10 ... Solid-state image sensor 10F ... Solid-state image sensor filter 11 ... Photoelectric conversion element 12B ... Blue filter 12G ... Green filter 12R ... Red filter 12P ... Infrared light path filter 13 ... Etching stopper layer 14 ... Infrared light cut Filters 15, 25 ... Oxygen blocking layer 16, 26 ... Microlens 21 ... Semiconductor substrate 24 ... Infrared light cut precursor layer

Claims (8)

A process of forming at least one color filter and an infrared light path filter among the red (R), green (G), and blue (B) color filters on a semiconductor substrate.
Of the red (R), green (G), and blue (B) color filters, an infrared light cut precursor is formed on the semiconductor substrate on which at least one color filter and an infrared light path filter are formed. The process of forming the layer and
A method for manufacturing a filter for a solid-state image sensor, which comprises a step of forming an infrared light cut filter on the color filter by dry etching the infrared light cut precursor layer. In the step of forming the infrared light cut precursor layer, at least one color filter and an infrared light pass filter among the red (R), green (G), and blue (B) color filters are used. The infrared light cut precursor layer is formed on the semiconductor substrate on which the above is formed so as to cover the surfaces of the color filter and the infrared light path filter.
In the step of forming the infrared light cut filter, the infrared light cut precursor layer is dry-etched so as to cover the surface of the color filter while exposing the surface of the infrared light pass filter. The method for manufacturing a filter for a solid-state image sensor according to claim 1, wherein the infrared light cut filter is formed. The infrared light path filter has a thicker film thickness than the red (R), green (G), and blue (B) color filters, and has the red (R), green (G), and blue colors. Among the color filters of (B), the height difference from the color filter on the uppermost surface is within the range of 0.5 μm or more and 1.0 μm or less.
The method for manufacturing a filter for a solid-state image sensor according to claim 1 or 2, wherein the dry etching amount of the infrared light cut precursor layer is 1.0 μm or less. Among the red (R), green (G), and blue (B) color filters, the thickness of the uppermost color filter is within the range of 0.5 μm or more and 1.0 μm or less.
The method for manufacturing a filter for a solid-state image sensor according to any one of claims 1 to 3, wherein the thickness of the infrared light cut precursor layer is in the range of 0.5 μm or more and 1.1 μm or less. Prior to forming the infrared light cut precursor layer, poly is applied on the surface of the infrared light path filter and on the surface of each of the red (R), green (G), and blue (B) color filters. The method for manufacturing a filter for a solid-state image sensor according to any one of claims 1 to 4, further comprising a step of forming an etching stopper layer made of siloxane. A step of forming an oxygen blocking layer covering the surface of the infrared light cut filter and the surface of the infrared light pass filter, and
The method for manufacturing a filter for a solid-state image sensor according to any one of claims 1 to 5, further comprising a step of forming a plurality of microlenses on the oxygen blocking layer. A step of forming a plurality of microlenses on a surface including the surface of the infrared light cut filter and the surface of the infrared light pass filter.
The method for manufacturing a filter for a solid-state image sensor according to any one of claims 1 to 5, further comprising a step of forming an oxygen blocking layer covering the surfaces of the plurality of microlenses. The process of preparing the semiconductor substrate and
A method for manufacturing a solid-state image sensor, comprising a step of forming a filter for a solid-state image sensor on the semiconductor substrate by the method for manufacturing a filter for a solid-state image sensor according to any one of claims 1 to 7.

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