JP2013033864A - Solid state imaging device manufacturing method, solid state imaging element and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve high reliability and reproducibility at low cost without damaging a semiconductor substrate when forming a fine convexoconcave structure for each pixel for antireflection of incident light.SOLUTION: A solid state imaging element manufacturing method comprises: a first step of forming a protection film having an etching selection ratio to a monocrystalline semiconductor substrate on a surface of the semiconductor substrate; a second step of forming a resist pattern of dots arranged with a predetermined pitch on the protection film; a third step of selectively removing the protection film by wet etching using the resist pattern formed in the second step as a mask; a fourth step of forming a structure of convexoconcave arranged with a predetermined pitch on the surface of the semiconductor substrate by etching the semiconductor substrate by wet etching using as a mask the protection film remaining after selectively removed in the third step; and a fifth step of removing the protection film remaining on the semiconductor substrate after forming the structure of convexoconcave in the fourth step.

Description

  The present technology relates to a method for manufacturing a solid-state imaging device, a solid-state imaging device, and an electronic apparatus.

  The solid-state imaging device includes, for example, a plurality of pixels arranged in a matrix, and includes a color filter and a lens provided corresponding to each pixel. Each pixel constituting the solid-state imaging device has a light receiving portion such as a photodiode having a photoelectric conversion function. The color filter provided corresponding to each pixel transmits light of any color component such as red, green, and blue. The lens provided corresponding to each pixel is provided corresponding to the light receiving part of each pixel, and condenses incident light from the outside to the corresponding light receiving part.

  In such a solid-state imaging device, in order to increase the conversion efficiency of the light-receiving unit, it is desirable that light incident on the solid-state imaging device is converted into an electrical signal by the photoelectric conversion function in the light-receiving unit without reflection. For this reason, it is desired to reduce the light reflection component at each interface of the laminated structure constituting the solid-state imaging device as much as possible.

  In addition, the reduction of light reflection at the interface of the laminated structure leads to a reduction in phenomena such as flare, ghost, and blooming that occur in the solid-state imaging device. Flare, ghost, and blooming occur when reflected light at the interface is reflected again by another member such as protective glass provided on the light incident side of the solid-state imaging device, and the reflected light enters as noise light.

  Regarding the reflection of light at such an interface, the difference in refractive index between the silicon substrate and the film formed on the surface of the silicon substrate is relatively large particularly at the interface due to the surface of the silicon substrate as the semiconductor substrate of the solid-state imaging device. Therefore, the loss of light generated by the reflection of light is large. A large loss due to light reflection leads to a decrease in sensitivity in the solid-state imaging device. For this reason, it is effective to provide a low reflection structure that suppresses the reflection of light at the interface by the semiconductor substrate from the viewpoint of suppressing the decrease in sensitivity due to the reflection of light.

  In recent years, for the purpose of improving the sensitivity of a solid-state imaging device and reducing the optical height, a so-called back-illuminated solid-state imaging device that receives light from the side opposite to the side on which a wiring layer is provided with respect to a semiconductor substrate has been developed. Proposed. In a back-illuminated solid-state imaging device, there is no wiring layer or circuit element on the light irradiation side, so the aperture ratio of the light receiving portion formed on the semiconductor substrate is increased and incident light is transmitted by the wiring layer or the like. Since the light is incident on the light receiving portion without being reflected, the sensitivity can be improved. Similarly, since there is no wiring layer or the like on the side where the semiconductor substrate is irradiated with light, the optical height can be reduced.

  According to the back-illuminated solid-state imaging device, although the sensitivity is improved as described above, there is no wiring layer on the side where the light is incident on the semiconductor substrate. There is concern about optical noise. For such optical noise, a light-shielding part such as a light-shielding film is provided between the light-receiving parts on the back side of the semiconductor substrate on the light irradiation side as in the technique described in Patent Document 1, for example. It is valid. In Patent Document 1, a light shielding portion formed between adjacent light receiving portions on the back surface side of a semiconductor substrate includes a trench portion formed at a desired depth from the back surface side of the semiconductor substrate, and a light shielding film embedded in the trench portion. There has been proposed a solid-state imaging device characterized by comprising:

  On the other hand, as a method for preventing reflection of incident light in a solid-state imaging device, it is known to coat an antireflection film using a single-layer or multilayer interference film. That is, in this method, the light incident side of the semiconductor substrate is coated with the antireflection film, and reflection of light at the interface by the semiconductor substrate is prevented. However, the method of coating the antireflection film has the following problems.

  First, the method of coating an antireflection film has excellent antireflection characteristics in a specific wavelength range with respect to incident light, but it is extremely difficult to form an excellent antireflection film in the entire wavelength range of visible light as incident light. Have difficulty. In addition, incident light in various directions exists for the solid-state imaging device, but it is difficult to provide the antireflection film with an antireflection function for all incident light in various directions.

  Furthermore, the antireflection ability of the antireflection film is sensitive to the film thickness of each film, and it is difficult to manage the production in order to maintain stable antireflection characteristics. Specifically, the wavelength range in which the antireflection film functions effectively changes depending on the film thickness. For example, when the film thickness of the antireflection film is optimized to function effectively for red light, sufficient antireflection function may not be obtained for blue or green light other than red. is there. As described above, the method of coating the antireflection film has many problems.

  Moreover, as a method using an antireflection film, for example, there is one described in Patent Document 2. In Patent Document 2, a film that lowers the interface state, such as a silicon oxide film, is formed on a semiconductor substrate on which a light receiving portion is formed, and a negative fixed charge, such as a hafnium oxide film, is formed on this film. There is disclosed a technique for obtaining an effect of suppressing dark current and preventing reflection by forming a film having the above. However, the method of forming a film for preventing reflection on a semiconductor substrate as in Patent Document 2 is difficult to cope with various wavelengths and directions of incident light as described above.

  In view of this, there has been proposed a method for preventing reflection of incident light by providing a so-called moth-eye structure with a fine protrusion at the interface between substances having different refractive indexes in a solid-state imaging device (for example, patents). Reference 3 and Patent Document 4). In the moth-eye structure, a large number of fine projection patterns are two-dimensionally arranged in the plane direction of the interface between substances.

  The principle of antireflection by the moth-eye structure is roughly as follows. Usually, the reflection of light is caused by a sudden change in refractive index. Therefore, by forming a large number of fine projection patterns as a moth-eye structure, the refractive index distribution at the interface between different substances becomes smooth in the light incident direction, that is, the height direction of the fine projections, and light reflection Is reduced. In order to obtain such an antireflection effect by the moth-eye structure, a pyramid shape or a cone shape is preferably used as the shape of the fine protrusions constituting the moth-eye structure.

  In addition, regarding the moth-eye structure, when the pitch, which is the spacing in the surface direction of the fine protrusion pattern, is smaller than the wavelength of light, the space occupancy of both substances forming the interface in the height direction of the fine protrusion gradually changes. The effective refractive index also changes smoothly when the material having the larger space occupancy is replaced with the change in the position of the fine protrusion in the height direction. In this way, the effective refractive index gradually changes, so that reflection of light is suppressed. Therefore, in the moth-eye structure, it is desirable that the pitch of the concavo-convex structure (fine concavo-convex structure) formed by fine protrusions is equal to or less than the wavelength of visible light.

  In the technique described in Patent Document 3, fine protrusions are provided on the surface of a passivation film formed on a semiconductor substrate. In Patent Document 3, an island-shaped resist pattern with 100 nm increments is formed by electron beam exposure, and reactive ion etching, which is dry etching, is performed using this resist pattern as a mask to form a pattern of fine protrusions.

  However, according to the method using reactive ion etching as described in Patent Document 3, when a fine protrusion is formed on a silicon substrate as a semiconductor substrate, the silicon substrate is damaged by plasma or the like used for etching. Is concerned. Since the silicon substrate is provided with a photodiode as a light receiving portion and a transistor, damage to the silicon substrate due to plasma or the like causes a white spot or an increase in dark current.

  Patent Document 4 proposes a method of forming a fine concavo-convex structure with silicon or the like on a silicon substrate via a gate oxide film made of a silicon oxide film. However, according to the technique of forming a fine concavo-convex structure on a silicon substrate through a thin film such as a gate oxide film as in Patent Document 4, absorption of incident light occurs due to the fine concavo-convex structure formed on the thin film, In some cases, the sensitivity may decrease. In addition, since the gate oxide film is interposed on the silicon substrate, the total thickness of the layer structure increases and there is a concern about color mixing.

  In the moth-eye structure, the higher the height of the fine concavo-convex structure, the lower the refractive index change in the height direction, and the higher the antireflection effect. However, as the height of the fine concavo-convex structure increases, the distance through which the incident light passes through the substance before reaching the light-receiving portion where the photoelectric conversion is performed becomes longer. From the point of view, it is not desirable. In this regard, there is no problem as long as a substance having a light absorption factor of 0 can be adopted as a substance through which incident light is transmitted, but it is difficult to realize a substance having a light absorption factor of zero with a material constituting a solid-state imaging device. It is.

  In order to solve the problem about the relationship between the height and sensitivity of such a fine concavo-convex structure, it is conceivable to use, for example, the technique disclosed in Patent Document 5. Patent Document 5 proposes a structure in which a layer made of a material having a refractive index smaller than that of the base material is laminated on the protrusions of the base material with respect to the fine concavo-convex structure. However, the technique of Patent Document 5 is a technique as an antireflection structure in a display device or the like, and is difficult to apply to a solid-state imaging device.

  On the other hand, in the technical field of solar cells, since reducing the reflectance increases the generated power per unit area, it is necessary to introduce an antireflection structure. Patent Document 6 proposes a method of forming an antireflection structure called an inverted pyramid texture on the surface of a silicon substrate. Specifically, Patent Document 6 discloses a technique using a photomask pattern capable of reducing a flat portion of a silicon surface and alkali selective etching as wet etching in order to form an antireflection structure. ing.

  However, the anti-reflection structure used for the solid-state imaging device is a forward pyramid type, that is, on the silicon substrate side, rather than the inverted pyramid type texture as described in Patent Document 6, because of the principle of the moth-eye structure as described above. A pyramidal structure with an upward convex shape is desirable. In addition, as described above, the moth-eye structure of the solid-state image sensor preferably has a pitch of the fine concavo-convex structure equal to or less than the wavelength of visible light. However, the stable formation of such a fine concavo-convex structure is merely an exposure machine. And it is difficult to improve the accuracy of the photomask pattern.

Japanese Unexamined Patent Publication No. 2011-3860 JP 2008-306154 A JP 2004-47682 A JP 2006-147991 A JP 2008-203473 A JP-A-7-142755

  As a feature of the fine concavo-convex structure, it is known that the reflectance dependency due to the wavelength of incident light is small. On the other hand, the structure of the solid-state imaging device is basically a multilayer structure. For this reason, for example, even if a fine concavo-convex structure is formed on the surface of a silicon substrate, a film having a refractive index different from that of the silicon substrate is usually formed on the fine concavo-convex structure.

  Therefore, by forming a fine relief structure on the surface of the silicon substrate, even if the wavelength dependence of the reflection characteristics with respect to incident light on the surface of the silicon substrate is reduced, due to the interference phenomenon with the upper layer provided on the silicon substrate, As a whole solid-state imaging device, the reflectance has wavelength dependency. In other words, when the moth-eye structure provided on the silicon substrate is viewed as a single unit, the wavelength dependency of the reflectance is low, but the moth-eye structure is applied to the solid-state image sensor, which is caused by interference due to the stacked structure of the upper layer of the silicon substrate. Thus, the wavelength dependence of the reflectance occurs.

  In addition, the wavelength dependency of the reflectance in the moth-eye structure changes depending on the moth-eye structure itself, such as the height of the fine uneven structure. That is, for example, when the height of the fine concavo-convex structure is different, the wavelength dependency of the reflectance is also different. Therefore, for the moth-eye structure provided on the silicon substrate, it is possible to create a fine concavo-convex structure suitable for each pixel of the solid-state imaging device, specifically for each color of the color filter formed on the upper layer side that is the light incident side. desirable.

  In this regard, Japanese Patent Application Laid-Open No. H10-228707 discloses that a fine concavo-convex structure is created for each pixel. However, Patent Document 4 does not describe in detail the manufacturing method of the fine concavo-convex structure. It is not easy in terms of manufacturing method to create a sub-wavelength concavo-convex structure whose pitch is shorter than the wavelength of light at the same interface, and a manufacturing method for forming a fine concavo-convex structure for each pixel is an important technique.

  Further, in Patent Document 1, as described above, a technique for providing a light shielding portion such as a light shielding film between light receiving portions on the back surface side of a semiconductor substrate has been proposed. In the manufacturing method for providing a light shielding portion, the light shielding portion is configured. The trench portion to be formed is formed using a dry etching method. Thus, according to the manufacturing method using dry etching, as in the case of Patent Document 3, damage such as crystal defects occurs on the silicon substrate, and the processing method itself may cause noise such as white spots. .

  The purpose of this technology is solid-state imaging that can obtain high reliability and reproducibility at low cost without damaging the semiconductor substrate when creating a fine concavo-convex structure for preventing reflection of incident light for each pixel. It is providing the manufacturing method of an element.

  Another object of the present technology is to obtain an antireflection function without depending on the wavelength of incident light, and to suppress a phenomenon caused by reflection of incident light such as flare, ghost, and blooming. It is an object to provide a solid-state imaging device and an electronic device that can be used.

  A method for manufacturing a solid-state imaging device according to the present technology includes a first step of forming a protective film having an etching selectivity with respect to the semiconductor substrate on a surface of a semiconductor substrate made of a single crystal, and the protective film on the protective film. A second step of forming a dot-shaped resist pattern arranged at a predetermined pitch, and a wet etching using the resist pattern formed in the second step as a mask selectively removes the protective film. 3 and by etching the semiconductor substrate by wet etching using the protective film remaining after being selectively removed in the third step as a mask, the predetermined surface is formed on the surface of the semiconductor substrate. A fourth step of forming a concavo-convex structure arranged at a pitch; and after the formation of the concavo-convex structure by the fourth step, before remaining on the semiconductor substrate A fifth step of removing the protective film, is intended to include.

  In the method for manufacturing a solid-state imaging device according to the present technology, preferably, in the second step, the dot-shaped resist pattern is arranged at a predetermined pitch for each pixel arranged in the pixel region on the semiconductor substrate. Place with.

  In the method for manufacturing a solid-state imaging device according to the present technology, it is preferable that the second step includes arranging the pixels together with the dot-shaped resist pattern at a predetermined interval between the pixels adjacent to each other. A linear resist pattern arranged along the line is formed, and the fourth step is performed at a position corresponding to the linear resist pattern facing each other between the adjacent pixels together with the concavo-convex structure. A linear groove is formed.

  In the method for manufacturing a solid-state imaging device according to the present technology, preferably, after the fifth step, the surface of the semiconductor substrate on the side where the uneven structure is formed is lower than the refractive index of the semiconductor substrate. And forming an intermediate film having a refractive index higher than the refractive index of the film on the semiconductor substrate side among the films constituting the laminated structure provided on the side where the uneven structure is formed with respect to the semiconductor substrate. The process is further included.

  A solid-state imaging device according to an embodiment of the present technology includes a semiconductor substrate having a pixel region in which a plurality of pixels including a light receiving unit having a photoelectric conversion function is arranged, and light received by the light receiving unit of the semiconductor substrate. A color filter provided for each pixel on the incident side, and the semiconductor substrate has fine pyramid-shaped projections arranged on the surface on the light incident side at a predetermined pitch for each pixel. It has a concavo-convex structure.

  Moreover, in the solid-state imaging device according to the present technology, it is preferable that the semiconductor substrate has a linear groove formed between surfaces adjacent to each other and a surface parallel to a surface on which the pyramidal projection is formed.

  Moreover, the solid-state imaging device according to the present technology is preferably configured such that the semiconductor substrate and the film on the semiconductor substrate side of the semiconductor substrate and the film constituting the stacked structure provided on the side where the uneven structure is present with respect to the semiconductor substrate. And an intermediate film having a refractive index lower than the refractive index of the semiconductor substrate and higher than the refractive index of the film closest to the semiconductor substrate.

  An electronic apparatus according to the present technology includes a solid-state imaging device, an optical system that guides incident light to a light receiving unit of the solid-state imaging device, a drive circuit that generates a drive signal for driving the solid-state imaging device, and the solid-state imaging A signal processing circuit for processing an output signal of the element, and the solid-state imaging device is made of a single crystal, and a semiconductor substrate having a pixel region in which a plurality of pixels including a light receiving unit having a photoelectric conversion function are arranged; A color filter provided for each of the pixels on the side on which light received by the light receiving portion of the semiconductor substrate is incident, and the semiconductor substrate has a surface on the side on which the light is incident for each pixel. It has a concavo-convex structure with fine pyramidal projections arranged at a predetermined pitch.

  According to the present technology, it is possible to obtain high reliability and reproducibility at low cost without damaging the semiconductor substrate when forming a fine concavo-convex structure for preventing reflection of incident light for each pixel. In addition, an antireflection function can be obtained without depending on the wavelength of incident light, and a phenomenon caused by reflection of incident light such as flare, ghost, and blooming can be suppressed.

FIG. 3 is a cross-sectional view illustrating a configuration of a solid-state imaging element according to an embodiment of the present technology. FIG. 3 is a plan view showing an antireflection structure and an interpixel separation structure included in a solid-state imaging device according to an embodiment of the present technology. FIG. 3 is a cross-sectional view taken along the line ABCD in FIG. 2. FIG. 3 is a cross-sectional view taken along the line E-F-G-H in FIG. 2. The figure which shows an example of the uneven | corrugated structure dependence of the reflection spectrum in the solid-state image sensor which concerns on one Embodiment of this technique. Sectional drawing which shows the modification of the solid-state image sensor which concerns on one Embodiment of this technique. Explanatory drawing about the manufacturing method of the solid-state image sensor which concerns on one Embodiment of this technique. Explanatory drawing about the manufacturing method of the solid-state image sensor which concerns on one Embodiment of this technique. Explanatory drawing about the manufacturing method of the solid-state image sensor which concerns on one Embodiment of this technique. Explanatory drawing about the manufacturing method of the solid-state image sensor which concerns on one Embodiment of this technique. Explanatory drawing about the manufacturing method of the solid-state image sensor which concerns on one Embodiment of this technique. Sectional drawing which shows the structure of the solid-state image sensor which concerns on other embodiment of this technique. Explanatory drawing about the manufacturing method of the solid-state image sensor which concerns on other embodiment of this technique. The figure which shows the simulation result about the effect of the solid-state image sensor concerning other embodiment of this art. Explanatory drawing about the simulation result about the effect of the solid-state image sensing device concerning other embodiments of this art. The figure which shows the simulation result about the wavelength dependence of the antireflection structure which the solid-state image sensor which concerns on one Embodiment of this technique has. The figure which shows the structural example of the electronic device which concerns on one Embodiment of this technique.

  The present technology focuses on the fact that in a solid-state imaging device, the difference in refractive index is relatively large at the interface of a semiconductor substrate made of a single crystal, and the loss of light generated by the reflection of light is large. By using etching characteristics along the crystal plane orientation of the semiconductor substrate, a concavo-convex structure composed of fine projection groups having different sizes for each pixel is formed. Hereinafter, embodiments of the present technology will be described.

[Configuration of solid-state image sensor]
The configuration of the solid-state imaging device 1 according to the first embodiment of the present technology will be described with reference to FIG. The solid-state imaging device 1 according to the present embodiment is a CMOS (Complementary Metal Oxide Semiconductor) type solid-state imaging device. The solid-state imaging device 1 has a semiconductor substrate 2 made of single crystal silicon. The solid-state imaging device 1 has a pixel region 3 and a peripheral circuit region provided around the pixel region 3 in a plan view of the semiconductor substrate 2.

  The pixel area 3 is an imaging area provided on the semiconductor substrate 2 and includes a plurality of pixels 5 provided in a predetermined arrangement. The pixel 5 is formed on the semiconductor substrate 2. In the present embodiment, a general square lattice arrangement in which the plurality of pixels 5 are arranged in a matrix in a planar manner in the pixel region 3 is employed as the arrangement of the plurality of pixels 5. In this case, the plurality of pixels 5 are arranged in a two-dimensional matrix in the vertical direction (vertical direction) and the horizontal direction (horizontal direction), for example, along the rectangular pixel region 3.

  The pixel region 3 has an effective pixel region that generates, amplifies, and reads out signal charges by photoelectric conversion in each pixel 5, and an optical black level region that outputs optical black serving as a black level reference. Usually, the optical black level region is formed on the outer periphery of the effective pixel region.

  The pixel 5 includes a photodiode 6 as a light receiving portion having a photoelectric conversion function, and a plurality of MOS transistors 7. The photodiode 6 has a light receiving surface, and generates a signal charge in an amount corresponding to the amount of light (intensity) of light incident on the light receiving surface. The photodiode 6 is formed so as to cover the entire area of the semiconductor substrate 2 in the thickness direction.

  In the present embodiment, the photodiode 6 has an n-type semiconductor region 8 as the first conductivity type and a p-type semiconductor region 9 as the second conductivity type formed so as to face both the front and back surfaces of the semiconductor substrate 2. And a pn junction type photodiode. The p-type semiconductor region 9 included in the photodiode 6 also serves as a hole charge accumulation region for dark current suppression. The pixel 5 includes, as the plurality of MOS transistors 7, transistors that respectively handle amplification, transfer, selection, and resetting of signal charges generated by the photodiode 6, for example.

  The MOS transistor 7 has a source / drain region (not shown) and a gate electrode 10. The source / drain regions of the MOS transistor 7 are formed as n-type regions in the p-type semiconductor well region 11 formed on the surface 2 a side, which is one plate surface side of the semiconductor substrate 2. The gate electrode 10 is formed on the surface 2a of the semiconductor substrate 2 between the source and drain regions of the MOS transistor 7 via a gate insulating film. As described above, each pixel 5 including the photodiode 6 and the MOS transistor 7 is separated by the element isolation region 12. The element isolation region 12 is formed as a p-type semiconductor region and is grounded.

  As described above, in the solid-state imaging device 1 according to the present embodiment, the semiconductor substrate 2 is made of single crystal silicon, and is a pixel region in which a plurality of pixels 5 including the photodiodes 6 as light receiving units having a photoelectric conversion function are arranged. 3. Note that the material of the semiconductor substrate 2 is not limited to single crystal silicon, and may be any single crystal semiconductor material that can be applied as a material of the semiconductor substrate constituting the solid-state imaging device.

  Further, in the solid-state imaging device 1, various circuits for operating the solid-state imaging device 1 are arranged in the peripheral circuit region provided around the pixel region 3 as described above. The circuits arranged in the peripheral circuit area include a vertical scanning circuit and a horizontal scanning circuit for selecting pixels in the vertical direction and the horizontal direction, a signal processing circuit for processing an output signal from each pixel 5, and a signal Includes an output circuit that performs predetermined signal processing on the signals that are sequentially supplied from the processing circuit and outputs them, a control circuit that generates clock signals and control signals that serve as a reference for the operation of these circuits, and controls each circuit. It is.

The solid-state image sensor 1 of this embodiment is a so-called back-illuminated CMOS solid-state image sensor. For this reason, the laminated wiring layer 13 is provided on the surface 2 a of the semiconductor substrate 2. The stacked wiring layer 13 has a plurality of wirings 15 stacked via an interlayer insulating film 14. The interlayer insulating film 14 is composed of, for example, a silicon oxide film formed of silicon dioxide (SiO ₂ ). The plurality of wirings 15 are formed of different metals, for example, and are connected to each other through plugs formed between layers. In the present embodiment, the wiring layer provided on one plate surface side of the semiconductor substrate 2 is the laminated wiring layer 13 having a plurality of wirings, but is not limited thereto, and is a wiring layer having a single-layer structure. Also good.

On the other hand, an antireflection film 20 is provided on the back surface 2 b which is the other plate surface of the semiconductor substrate 2. The antireflection film 20 is formed as an inorganic film such as a silicon nitride film (SiN film). A protective passivation film 16 is provided on the antireflection film 20. The passivation film 16 is a flattened film and has optical transparency. The passivation film 16 is formed as an inorganic film such as a silicon oxide film (SiO ₂ film). Note that an insulating film or the like that functions as an antireflection film is appropriately provided between the semiconductor substrate 2 and the passivation film 16.

  A color filter layer 17 is provided on the passivation film 16. The color filter layer 17 is divided into color filters 18 provided corresponding to the respective pixels 5 arranged in the pixel region 3. That is, the color filter layer 17 is divided into a plurality of color filters 18 for each photodiode 6 constituting each pixel 5. In the solid-state imaging device 1 of the present embodiment, each color filter 18 is a filter portion of any color of red (R), green (G), and blue (B), and transmits light of each color component. . Each color filter 18 is a so-called on-chip color filter, and is formed according to the arrangement of the plurality of pixels 5. As described above, the solid-state imaging device 1 of the present embodiment includes the color filter 18 provided for each pixel 5 on the side where the light received by the photodiode 6 of the semiconductor substrate 2 is incident, that is, on the surface side.

  A plurality of microlenses 19 are provided on the color filter layer 17. The microlens 19 is a so-called on-chip microlens and is formed for each pixel 5 corresponding to the photodiode 6 constituting the pixel 5. Therefore, the plurality of microlenses 19 are arranged in a matrix on a plane, for example, like the pixels 5. The microlens 19 collects incident light from the outside on the photodiode 6 of the corresponding pixel 5. The microlens 19 is made of an inorganic material such as SiN (silicon nitride), for example.

  As described above, the solid-state imaging device 1 of the present embodiment has the color filter layer 17 and the microlens 19 on the back surface 2b side opposite to the front surface 2a side on which the laminated wiring layer 13 is provided. Has a back-illuminated structure. That is, in the solid-state imaging device 1, the laminated wiring layer 13 and the color filter layer 17 are provided on different plate surface sides with respect to the semiconductor substrate 2, and the back surface 2 b on which light is incident on the semiconductor substrate 2. A laminated wiring layer 13 is provided on the surface 2a side opposite to the side.

  In the back-illuminated solid-state imaging device 1, the light incident from the microlens 19 side passes through the color filter layer 17 and then is received by the photodiode 6 of the pixel 5 without passing through the laminated wiring layer 13. . For this reason, in the solid-state imaging device 1, light incident from the microlens 19 side is received by the photodiode 6 of the pixel 5 without being blocked by the laminated wiring layer 13, so that a so-called surface irradiation type structure is obtained. On the other hand, it is easy to secure a substantial light receiving area of the photodiode 6 and relatively high sensitivity can be obtained. Further, since the laminated wiring layer 13 is provided on the surface 2a side opposite to the light incident side (the back surface 2b side) with respect to the semiconductor substrate 2, the layout of the wiring 15 constituting the laminated wiring layer 13 is high. A degree of freedom can be obtained.

  Note that the solid-state imaging device 1 of the present embodiment is a backside illumination type, but may be a frontside illumination type in which the laminated wiring layer 13 is provided on the front surface 2a side where light is incident on the semiconductor substrate 2. In the case of the surface irradiation type structure, the color filter layer 17 and the microlens 19 are disposed on the same side as the laminated wiring layer 13 with respect to the semiconductor substrate 2 via the laminated wiring layer 13 provided on one side of the semiconductor substrate 2. It is formed.

[Antireflection structure]
The solid-state imaging device 1 of the present embodiment having the above-described configuration has a fine antireflection structure for preventing reflection of incident light on the surface (plate surface) on the side where light enters in the semiconductor substrate 2. It has an antireflection structure by protrusions, a so-called moth-eye structure. In the solid-state imaging device 1, the difference in refractive index is relatively large at the interface of the semiconductor substrate 2 made of single crystal silicon, and the loss of light generated by the reflection of light is large. Therefore, in the solid-state imaging device 1 of the present embodiment, an antireflection structure composed of fine protrusion groups is provided on the surface of the semiconductor substrate 2 on the light incident side.

  As shown in FIGS. 1 and 2, in the solid-state imaging device 1 of the present embodiment, the semiconductor substrate 2 is arranged at a predetermined pitch for each pixel 5 on the back surface 2 b that is the surface on the light incident side. The concavo-convex structure 30 is formed by a fine pyramidal projection 31. As shown in FIG. 2, in the present embodiment, the protrusion 31 constituting the concavo-convex structure 30 has a quadrangular pyramid shape. That is, the protrusions 31 constituting the concavo-convex structure 30 have a forward pyramid shape, that is, a convex pyramid shape on the light incident side (upper side in FIG. 1).

  FIG. 2 is a partially enlarged plan view of the semiconductor substrate 2 showing a part of the back surface 2 b of the semiconductor substrate 2. Since the uneven structure 30 is provided on the back surface 2 b of the semiconductor substrate 2, FIG. 2 shows a plan view of the uneven structure 30. FIG. 2 shows a boundary portion between four pixels 5 in 2 rows and 2 columns in an array of a plurality of pixels 5 arranged in a matrix.

  As shown in FIG. 2, the quadrangular pyramidal protrusions 31 have a square shape or a rectangular shape in plan view (a shape corresponding to the shape of the bottom surface in the quadrangular pyramid shape), and a plurality of the plan view shapes arranged in a matrix. Provided in a state of being arranged along the arrangement of the pixels 5. In other words, the protrusions 31 constituting the concavo-convex structure 30 have a vertical direction (vertical direction) and a horizontal direction (horizontal direction) in the arrangement of the plurality of pixels 5 in which the sides forming the outer shape of the planar view are arranged in a two-dimensional matrix. ).

  The concavo-convex structure 30 constituted by the group of protrusions 31 is provided for each pixel 5 arranged in the pixel region 3. As shown in FIG. 2, the plurality of protrusions 31 constituting the concavo-convex structure 30 are provided in the concavo-convex area 32 partitioned in a rectangular shape in each pixel 5 arranged in the pixel area 3. The uneven area 32 in each pixel 5 is an area including a range where the photodiode 6 of the corresponding pixel 5 exists in a plan view. The projections 31 are arranged in a matrix along the arrangement of the pixels 5 without a gap in the uneven region 32 of each pixel 5 in a state of being adjacent in the vertical direction and the horizontal direction.

  As described above, the protrusion 31 constituting the concavo-convex structure 30 provided for each pixel 5 has a different size for each pixel 5. Specifically, the size of the protrusion 31 constituting the concavo-convex structure 30 differs for each color of the color filter 18 provided for each pixel 5 as described above, that is, for each wavelength of incident light. In the solid-state imaging device 1 of the present embodiment, a so-called Bayer array is employed as the color array of the color filter 18 mounted on the photodiode 6 of each pixel 5. In the Bayer array, green (G) filters are arranged in a checkered pattern, and four pixels in 2 rows and 2 columns are used as structural units. An (R) filter and a blue (B) filter are arranged. For convenience, FIG. 1 shows a cross-sectional view in which green (G), red (R), and blue (B) are arranged as colors of the color filter 18.

  Of the four pixels 5 in 2 rows and 2 columns shown in FIG. 2, the upper right pixel 5 is a red (R) pixel 5 having a red color filter 18 (18R) (hereinafter referred to as “red pixel 5R”). The upper left and lower right pixels 5 are green (G) pixels 5 (hereinafter referred to as “green pixels 5G”) having a green color filter 18 (18G), and the lower left pixels 5 are blue. This is a blue (B) pixel 5 (hereinafter referred to as “blue pixel 5B”) having the color filter 18 (18B).

  In the present embodiment, the size of the protrusion 31 constituting the concavo-convex structure 30 is the red pixel 5R, the green pixel 5G, and the blue pixel 5B in order from the largest. That is, with respect to the size of the protrusion 31 that is different for each color of the color filter 18, the protrusion 31 (hereinafter referred to as “red protrusion 31R”) provided in the uneven region 32 of the red pixel 5R is the largest, and then the green color. The protrusion 31 provided in the uneven area 32 of the pixel 5G (hereinafter referred to as “green protrusion 31G”) is large, and the protrusion 31 provided in the uneven area 32 of the blue pixel 5B (hereinafter referred to as “blue protrusion 31B”). Is the smallest. The shape of the protrusion 31 is similar between the red protrusion 31R, the green protrusion 31G, and the blue protrusion 31B regardless of the color of the color filter 18.

  Since the protrusions 31 arranged in the uneven region 32 of each pixel 5 are arranged without gaps in the vertical direction and the horizontal direction as described above, the size of the protrusion 31 is the size of the array of the protrusions 31 in each uneven region 32. Corresponds to the pitch. That is, the size relationship between the protrusions 31 corresponds to the relationship between the pitches of the protrusions 31 in the concavo-convex region 32. The larger the pitch, the larger the size, and the smaller the pitch, the smaller the size.

The size of the projection 31 includes the height of the projection 31 and the size (area) of the projection 31 in plan view. Here, the height of the projection 31 is quadrangular pyramid protruding dimension in shape (e.g. FIG. 3, reference numeral h see _R, etc.) of the projection 31 is, the size of the plan view shape of the protrusion 31, as the four- This corresponds to the size (area) of a plan view shape that is square or rectangular in the pyramid shape.

As shown in FIGS. 3 and 4, in the solid-state imaging device 1 of the present embodiment, the size of the red protrusion 31R, the green protrusion 31G, and the blue protrusion 31B depends on the size of the color filter 18 as described above. As for the pitch in the arrangement of the protrusions 31 of each color, the magnitude relationship of p _R > p _G > p _B is established. Here, _{p R} is the pitch of the red projection 31R, _{p G} is the pitch of the green projection 31G, _{p B} is the pitch of the blue projection 31B. Further, the pitch in the arrangement of the protrusions 31 group is a dimension corresponding to one period in the periodically formed protrusions 31 group, for example, a dimension between vertices between adjacent protrusions 31. In the present embodiment, it is assumed that the pitches in the vertical direction and the horizontal direction in the protrusions 31 of each concavo-convex structure 30 provided for each pixel 5 are equal.

Further, as shown in FIGS. 3 and 4, with respect to the height of the protrusion 31 corresponding to each color pixel 5, the heights of the red protrusion 31R, the green protrusion 31G, and the blue protrusion 31B are set to h _R , Assuming h _G and h _B , a magnitude relationship of h _R > h _G > h _B is established. Similarly, the size (area) of the projection 31 corresponding to the pixel 5 of each color in plan view is a red projection 31R, a green projection 31G, and a blue projection 31B in order from the largest.

  The magnitude relationship between the protrusions 31 in the solid-state imaging device 1 according to the present embodiment corresponds to the wavelength of light of each color filter 18. That is, the wavelength of the light of the color of each color filter 18 becomes shorter in the order of red, green, and blue, and the size of the protrusion 31 is smaller as the wavelength is shorter. However, the relationship between the size of the protrusion 31 corresponding to each color and the wavelength of light of each color is not limited to this embodiment. For example, the longer the light wavelength, the smaller the size of the protrusion 31 may be. In addition, the size of the protrusion 31 corresponding to each color and the wavelength of light of each color are not limited to those having a unique relationship as in the present embodiment, for example.

  According to the solid-state imaging device 1 of the present embodiment having the antireflection structure as described above, an antireflection function can be obtained without depending on the wavelength of incident light, and incident light such as flare, ghost, and blooming is reflected. It is possible to suppress the phenomenon caused by The fact that such an effect can be obtained will be specifically described.

  As described above, by forming the concavo-convex structure 30 as the fine concavo-convex structure on the semiconductor substrate 2, the wavelength dependence of the reflection characteristic with respect to incident light on the surface of the semiconductor substrate 2 is reduced, but the solid-state imaging device 1 as a whole The reflectance depends on the wavelength due to the interference caused by the laminated structure of the upper layer of the semiconductor substrate 2. The wavelength dependency of the reflectance by forming the concavo-convex structure 30 on the semiconductor substrate 2 depends on the structure of the concavo-convex structure 30 such as the height of the concavo-convex structure 30 (the height of the protrusion 31, hereinafter the same). And change.

  FIG. 5 shows an example of a simulation result of the change in the wavelength dependency of the reflectance due to the structure of the uneven structure 30, that is, the dependency of the reflection spectrum on the uneven structure 30. In the graph shown in FIG. 5, a graph G1 shows a reflection spectrum when the height of the concavo-convex structure 30 is 100 nm, a graph G2 shows a reflection spectrum when the height of the concavo-convex structure 30 is 300 nm, and a graph G3 shows The reflection spectrum in case the height of the uneven structure 30 is 500 nm is shown. Graph G4 shows a reflection spectrum when a silicon nitride film (SiN film) having a thickness of 58 nm is formed on the surface of the semiconductor substrate 2 as a single-layer antireflection film instead of the concavo-convex structure 30, and the graph G5 shows 2 shows a reflection spectrum by the surface of the semiconductor substrate 2 itself made of single crystal silicon (where the concavo-convex structure 30 and the antireflection film are not present).

  As can be seen from the graphs G1, G2, and G3 in FIG. 5, the reflectance value periodically changes as the wavelength changes. That is, it can be seen from the graphs G1, G2, and G3 that the wavelength dependency of the reflectance occurs in the configuration in which the semiconductor substrate 2 has the concavo-convex structure 30. Similarly, in the case of the single-layer antireflection film shown in the graph G4, the reflectance is also wavelength-dependent. On the other hand, in the case of the surface of the single crystal silicon semiconductor substrate 2 shown by the graph G5, the reflectance is wavelength-dependent, but the spectrum shape is generally gentle.

  Thus, also from the simulation results, the reflectance of incident light has wavelength dependency, and the wavelength dependency also depends on the structure of the concavo-convex structure 30 itself such as the height of the concavo-convex structure 30. Recognize. Therefore, as in the solid-state imaging device 1 of the present embodiment, by forming the concavo-convex structure 30 for each color of the pixel 5, an optimal antireflection function can be obtained for each pixel 5 from the viewpoint of reducing the reflectance. Can do.

  With respect to the uneven structure 30 created for each pixel 5, the optimal size of the protrusion 31 corresponding to each color of the pixel 5 is a factor on the semiconductor substrate 2 that causes the reflectance to be wavelength-dependent in the solid-state imaging device 1. It is determined based on the thickness, material, refractive index, etc. of each layer in the laminated structure. That is, in the solid-state imaging device 1 according to the present embodiment, the color of each pixel 5 is set so that the reflectance is as small as possible based on the thickness of each layer of the stacked structure on the semiconductor substrate 2. By determining the optimum size of the protrusion 31, a high antireflection function can be obtained without depending on the wavelength of incident light. Thereby, problems such as flare, ghost and blooming caused by reflected light in the solid-state imaging device 1 can be suppressed.

  Further, the concavo-convex structure 30 formed on the surface of the semiconductor substrate 2 can also be used as an alignment mark for alignment of the semiconductor substrate 2 in the manufacturing process of the solid-state imaging device 1. Thereby, when the alignment mark is required for the semiconductor substrate 2, the step of forming the alignment mark can be omitted.

[Separation structure between pixels]
Next, an inter-pixel separation structure included in the solid-state imaging device 1 of the present embodiment will be described. The solid-state imaging device 1 of the present embodiment has a shape portion that functions as an inter-pixel separation structure on the front surface (back surface 2b) on the light incident side of the semiconductor substrate 2.

  Specifically, as shown in FIGS. 1 to 4, in the solid-state imaging device 1 of the present embodiment, the semiconductor substrate 2 includes a surface on which the protrusions 31 of the concavo-convex structure 30 are formed between the pixels 5 adjacent to each other. It has the linear groove part 40 which consists of a parallel surface. In this semiconductor substrate 2, the groove part 40 provided between the pixels 5 functions as an inter-pixel separation structure.

  The groove portion 40 is provided in a lattice shape along the boundary between the pixels 5 arranged in a matrix at the back surface 2 b portion of the semiconductor substrate 2. The groove portion 40 has a lattice shape along the boundary between the pixels 5, and a main portion other than the intersection portion between the vertical groove portion 40 and the horizontal groove portion 40 is a V-shaped groove that is V-shaped in a cross-sectional view. (See FIGS. 3 and 4). The groove portion 40 is formed by a pair of inclined surfaces 41 inclined with respect to the direction along the plate surface of the semiconductor substrate 2, and has a common cross-sectional shape in each of the vertical direction and the horizontal direction.

  The inclined surface 41 that forms the groove 40 is formed as a surface parallel to the surface on which the protrusion 31 of the concavo-convex structure 30 is formed. Specifically, with reference to FIG. 3, one of the slopes 41 a (on the left side in FIG. 3) of the pair of slopes 41 forming the groove portion 40 has a quadrangular pyramid shape in the protrusion 31 constituting the concavo-convex structure 30. It is formed as a plane parallel to the right triangular slope 31a to be formed. Similarly, the other inclined surface 41 b (on the right side in FIG. 3) among the inclined surfaces forming the groove portion 40 is parallel to the right triangular inclined surface 31 b forming a quadrangular pyramid shape in the protrusion 31 constituting the concavo-convex structure 30. Formed as a surface. The slopes 41 (41a, 41b) forming the groove portions 40 and the slopes 31a, 31b forming the protrusions 31 are surfaces obtained according to the plane orientation of the semiconductor substrate 2 made of single crystal silicon.

  Further, the width dimension of the groove portion 40 (see FIG. 2, reference sign w <b> 1) is basically larger than the pitch in the arrangement of the protrusions 31 group constituting the uneven structure 30 in the pixel 5 of any color. However, the magnitude relationship between the width dimension of the groove 40 and the pitch in the arrangement of the projections 31 of the concavo-convex structure 30 is not limited to this embodiment. In the present embodiment, it is assumed that the width dimensions of the groove portions 40 arranged in the vertical direction (vertical direction) and the horizontal direction (horizontal direction) are equal to each other.

  According to the solid-state imaging device 1 of the present embodiment having the inter-pixel separation structure as described above, the groove portion 40 provided along the boundary between the pixels 5 becomes a digging portion between the adjacent pixels 5, and a certain pixel 5, the incidence of oblique light from the pixel 5 adjacent to the pixel 5 can be prevented, and color mixing can be suppressed.

  Here, the term “mixed color” refers to a part of light incident on the color filter 18 corresponding to the pixel 5 of one color at the boundary portion between adjacent pixels 5 where the pixels 5 of different colors are adjacent to each other as oblique light. This phenomenon is incident on the photodiode 6 of the color pixel 5. The mixed color also causes unevenness in sensitivity and image quality in the solid-state imaging device 1. Such a problem due to color mixing becomes conspicuous as the solid-state imaging device 1 is miniaturized or the number of pixels is increased.

  Therefore, according to the solid-state imaging device 1 of the present embodiment, the groove portion 40 provided between the pixels 5 can block oblique light from adjacent pixels 5 and suppress color mixing. In this way, from the viewpoint of suppressing color mixing, it is preferable that the depth of the groove 40, that is, the depth of digging of the semiconductor substrate 2 between the adjacent pixels 5 is deep. That is, as the depth of the groove portion 40 is increased, a higher color mixing prevention effect is obtained. On the other hand, when the depth of the groove portion 40 is increased, it becomes difficult to secure a region of a silicon layer that performs photoelectric conversion, that is, a layer portion as the photodiode 6, due to the plane orientation of the semiconductor substrate 2. For this reason, the depth of the groove 40, that is, the amount of digging of the semiconductor substrate 2 between adjacent pixels is appropriately determined based on the sensitivity required in the solid-state imaging device 1 and the color separation performance for obtaining the color mixing prevention effect. The amount is determined.

(Modification)
A modification of the solid-state imaging device 1 of the present embodiment is shown in FIG. As shown in FIG. 6, in this modification, the antireflection film 20 and the passivation film 16 provided on the semiconductor substrate 2 are omitted, and the color filter layer 17 is provided directly on the semiconductor substrate 2. That is, in the present modification, the color filter layer 17 divided into the plurality of color filters 18 is provided so as to cover the concavo-convex structure 30 and the groove 40 provided on the back surface 2 b side of the semiconductor substrate 2.

  As described above, the uneven structure 30 as the antireflection structure and the groove portion 40 as the inter-pixel separation structure provided on the back surface 2b side of the semiconductor substrate 2 are provided with the color filter layer 17 directly on the back surface 2b side of the semiconductor substrate 2. The present invention can also be applied to other configurations. The configuration of this modification example is preferable in that the layer structure of the solid-state imaging device 1 is simplified and the height of the solid-state imaging device 1 is reduced because the antireflection film 20 and the passivation film 16 are omitted.

[Method for Manufacturing Solid-State Imaging Device]
A method for manufacturing the solid-state imaging device 1 of the present embodiment (hereinafter referred to as “manufacturing method”) will be described with reference to FIGS. In the method for manufacturing the solid-state imaging device 1 described below, a process of forming the uneven structure 30 as an antireflection structure and the groove 40 as an inter-pixel separation structure will be mainly described.

  When performing the manufacturing method of this embodiment, as shown to Fig.7 (a), the process of preparing the semiconductor substrate 2 which consists of single crystal silicon is performed. As the semiconductor substrate 2, one having a (100) plane of single crystal silicon as the main surface (plate surface) is prepared. In other words, the semiconductor substrate 2 is cut out in parallel with the (100) plane, for example, to prevent defects on the surface. Therefore, in the semiconductor substrate 2 of the present embodiment, the flat surface 51 serving as the back surface 2b on which the uneven structure 30 is formed or the antireflection film 20 is provided corresponds to the (100) plane.

(About antireflection structure)
In the manufacturing method of this embodiment in which such a semiconductor substrate 2 is used, first, formation of the concavo-convex structure 30 as an antireflection structure will be described. In the manufacturing method of the present embodiment, first, as shown in FIG. 7B, a hard mask layer 52 is formed on the flat surface 51 of the semiconductor substrate 2. The hard mask layer 52 functions as a hard mask in a wet etching process performed on the semiconductor substrate 2 to be performed later by being selectively removed in a subsequent process. For this reason, the hard mask layer 52 is formed of a material having an etching selectivity with respect to the semiconductor substrate 2.

  In the present embodiment, the hard mask layer 52 is formed of a material having an etching selectivity with respect to single crystal silicon constituting the semiconductor substrate 2. As the material of the hard mask layer 52, for example, a material that is difficult to be etched by an alkaline solution is used.

The hard mask layer 52 is formed as a silicon oxide film (SiO ₂ film), for example. Specifically, the hard mask layer 52 is formed by, for example, a CVD method using TEOS (tetraethoxysilane) gas, or is formed as a SiO ₂ -based CVD film by a bias high density plasma CVD method.

  As described above, the manufacturing method according to the present embodiment includes the step of forming the hard mask layer 52 on the semiconductor substrate 2. This step corresponds to a first step of forming a protective film having an etching selectivity with respect to the semiconductor substrate 2 on the plane 51 which is the surface of the semiconductor substrate 2 made of single crystal silicon. That is, in the manufacturing method of the present embodiment, the hard mask layer 52 corresponds to a protective film having an etching selectivity with respect to the semiconductor substrate 2.

  Next, as shown in FIG. 7C, resist patterning is performed to form a dot-shaped resist mask 53 on the hard mask layer 52. As the material of the resist mask 53, a known resist material can be used. Microscopically, the dot-shaped resist mask 53 has a rectangular shape or a circular shape. The dot-shaped resist mask 53 is formed by, for example, photolithography.

The dot-shaped resist mask 53 is arranged at _a predetermined pitch pa. Specifically, as illustrated in FIGS. 2 and 9, the dot-shaped resist mask 53 includes each of the concavo-convex structures 30 in the concavo-convex area 32 of each pixel 5 that is an area including the photodiode 6 in a plan view. The protrusion 31 is formed at a position corresponding to the apex of the quadrangular pyramid shape. That is, the dot-shaped resist mask 53 is formed at a position corresponding to the center position of each protrusion 31 provided in the uneven region 32 in a plan view of the semiconductor substrate 2 as shown in FIG. Therefore, the dot-shaped resist mask 53 is arranged at _a predetermined pitch pa in the vertical direction and the horizontal direction in the concavo-convex region 32 of each pixel 5, and is arranged in a lattice point shape in a plane.

Further, as shown in FIG. 7 (c), the magnitude q _a resist mask 53 of dot shape affects the quadrangular pyramid shape of each protrusion 31 of the final relief structure 30. As the size q _a resist mask 53 is small, a shape in which the top portion is pointed in a quadrangular pyramid shape of the projection 31. And the anti-reflective effect by the uneven structure 30 as an anti-reflective structure becomes high, so that the top part of the processus | protrusion 31 is sharp. Therefore, the magnitude q _a resist mask 53 of dot shape is preferably as small as possible. Specifically, the magnitude _{q a} resist mask 53 of dot shape is preferably set in the range of 1 to 100 nm. The size q _a resist mask 53 of dot shape, the shape of the resist mask 53 is in the case of rectangular shape corresponds to the longitudinal or transverse dimension in the case of circular shape corresponding to the dimensions of the outer diameter.

Thus, the process of the present embodiment includes a step of forming a resist mask 53 of dot shape at a predetermined pitch p _a on the hard mask layer 52. This process corresponds to a second process of forming dot-shaped resist patterns arranged at a predetermined pitch on the hard mask layer 52.

  In the case of the solid-state imaging device 1 of the present embodiment, in the second step, dot-shaped resist patterns are arranged at a predetermined pitch for each pixel 5 arranged in the pixel region 3 on the semiconductor substrate 2.

Placement of the resist mask 53 of dot shape is because it corresponds to the position of the apex of each projection 31 constituting the as concavo-convex structure 30 described above, the pitch p _a in the sequence of the resist mask 53 of dot shape, eventually each pixel The pitch (p ₁ ) in the arrangement of the protrusions 31 of the concavo-convex structure 30 formed in the five concavo-convex regions 32. In other words, the concavo-convex structure 30 formed in the concavo-convex region 32 of each pixel 5 is formed in the concavo-convex region 32 of each pixel 5 so as to have the same size as the pitch of the array of projections 31 finally formed. that the pitch p _a sequence of resist mask 53 of dot shape are determined. That creates in the step of forming a resist mask 53 of the dot shape, the pitch p _a sequence of resist mask 53 by changing each pixel 5, in terms of the pitch of arrangement of the projections 31 group, a concavo-convex structure 30 Dividing is done.

Therefore, in this embodiment, with respect to the pitch of arrangement of the projections 31 groups, as shown in FIG. 9, the pitch p _a resist mask 53 of dot shape are formed in an uneven region 32 of the red pixel 5R is red projection it is the same size as the 31R of the pitch _{p R.} Similarly, the pitch p _a dot shape of the resist mask 53 formed on the green pixel 5G of irregular region 32 is the same size as the pitch p _G of the green projection 31G, the uneven region 32 of the blue pixel 5B pitch p _a resist mask 53 of dot shape is formed is the same size as the pitch p _B of the blue projection 31B.

Thus, in the step of forming the dot-shaped resist mask 53 on the hard mask layer 52, it is preferable to form the resist mask 53 at _a predetermined pitch pa for each pixel 5. Thereby, like the solid-state image sensor 1 of this embodiment, it can respond to the structure from which the pitch of the processus | protrusion 31 group of the uneven structure 30 differs for every pixel 5. FIG.

  Subsequently, as shown in FIG. 7D, the pattern of the dot-shaped resist mask 53 is transferred to the hard mask layer 52 by wet etching. That is, by using the dot-shaped resist mask 53 formed on the hard mask layer 52 as a mask, wet etching is performed on the hard mask layer 52, so that portions other than the portion corresponding to the resist mask 53 of the hard mask layer 52 are obtained. The portion is selectively removed, and a dot-shaped hard mask 54 is formed.

  A necessary characteristic for the chemical used in this wet etching step is that the hard mask layer 52 formed as a silicon oxide film can be etched, for example. Further, as a chemical solution used in this wet etching process, the resist mask 53 is a resistant chemical solution, and the resist mask 53 is less likely to be etched than the hard mask layer 52. A material having an etching selectivity (for example, 10 or more) with the hard mask layer 52 is used. Specifically, examples of the chemical liquid used in the wet etching process of the hard mask layer 52 include DHF (Diluted Hydrogen Fluoride) and BHF (Buffered Hydrogen Fluoride). Moreover, generally used conditions can be used as the temperature and concentration of the chemical solution in this wet etching step.

By selectively removing the hard mask layer 52 by wet etching using the dot-shaped resist mask 53 as a mask, the pattern of the dot-shaped resist mask 53 is transferred to the hard mask layer 52, and the hard mask layer A hard mask 54 is formed as a remaining portion of 52. That is, the hard mask 54 is a dot-shaped mask pattern arranged at _a predetermined pitch pa for each pixel 5, similarly to the resist mask 53.

  As described above, the manufacturing method of this embodiment includes a step of forming the dot-shaped hard mask 54 by transferring the pattern of the dot-shaped resist mask 53 to the hard mask layer 52 by wet etching. This step corresponds to a third step of selectively removing the hard mask layer 52 by wet etching using the dot-shaped resist mask 53 that is the resist pattern formed in the second step as a mask.

  Next, as shown in FIGS. 8A and 8B, the concavo-convex structure 30 is formed by processing the semiconductor substrate 2 by wet etching using the dot-shaped hard mask 54 as a mask. That is, the exposed portion other than the portion covered by the hard mask 54 on the flat surface 51 of the semiconductor substrate 2 is exposed to a chemical solution for wet etching, so that the back surface 2b portion of the semiconductor substrate 2 is etched and the plurality of protrusions 31 are exposed. The uneven structure 30 is formed.

An alkaline solution is used as a chemical solution used in the wet etching process. Specifically, NH ₄ OH (ammonium hydroxide), KOH (potassium hydroxide), tetramethylammonium hydroxide (TMAH: Tetramethyl Ammonium Hydroxide), NaOH ( Sodium hydroxide) and the like. In addition, the etching selectivity of the hard mask 54 to the semiconductor substrate 2 can be obtained by using generally used conditions as the temperature and concentration of the chemical solution in the wet etching process.

In the etching process of the semiconductor substrate 2 according to the alkaline solution, by utilizing the plane orientation dependence of the single crystal silicon constituting the semiconductor substrate 2, the opening width of the pattern of the hard mask 54 of dot shape of (pitch p _a) Self-stop etching controlled by size can be realized. As described above, the semiconductor substrate 2 having the (100) plane of the single crystal silicon as the main surface has a crystal plane that is difficult to be etched by the alkaline solution because of the plane orientation of the single crystal silicon. For this reason, when the semiconductor substrate 2 is etched from the (100) plane with the alkaline solution, a crystal plane that is difficult to be etched due to the plane orientation is precipitated, and the surface that receives the alkaline solution in the semiconductor substrate 2 is etched. Etching is automatically stopped when only difficult crystal planes are obtained.

  Specifically, as shown in FIG. 8A, etching with an alkaline solution using a dot-shaped hard mask 54 as a mask is started from a plane 51 which is a (100) plane in a semiconductor substrate 2 made of single crystal silicon. Then, as described above, etching of the semiconductor substrate 2 proceeds while the precipitation surface 2x as a crystal surface that is difficult to be etched due to the plane orientation relationship of the semiconductor substrate 2 is precipitated. For this reason, as shown in FIG. 8A, in the process of etching the semiconductor substrate 2 with an alkaline solution, etching is performed in parallel with the deposition surface 2x and the (100) plane (plane 51), which is the etching progress surface. Surface 55 exists. That is, the etching of the semiconductor substrate 2 with the alkaline solution proceeds while the etching surface 55 moves in a direction perpendicular to the (100) plane of the semiconductor substrate 2 (downward in FIG. 8), and the deposition surface 2x is deposited.

  Here, the precipitation surface 2x as a crystal plane that is difficult to be etched in the semiconductor substrate 2 is a slope defined as a (111) plane with respect to the (100) plane defining the plane 51. The (111) plane as the deposition plane 2x is difficult to etch into the alkaline solution because of the plane orientation of the semiconductor substrate 2. That is, the alkaline solution as described above is a solution that has an extremely small etching amount on the (111) plane as the deposition plane 2x. Further, the hard mask 54 having an etching selectivity with respect to the semiconductor substrate 2 is also difficult to be etched by the alkaline solution. For this reason, in the etching of the semiconductor substrate 2 with an alkaline solution, the position of the hard mask 54 is the apex, and between the deposited surfaces 2x facing each other in the vertical direction or the horizontal direction between the hard masks 54 adjacent to each other in the vertical direction or the horizontal direction. Then, the etching surface 55 is formed and the etching proceeds in parallel with the (100) surface, and at the same time, the precipitation surface 2x which is a (111) surface which is difficult to be etched is deposited.

  Then, as shown in FIG. 8B, when the etching progresses until the deposition surfaces 2x deposited between the adjacent hard masks 54 cross each other, the etching is substantially stopped. That is, as the etching of the semiconductor substrate 2 proceeds, the etching surface 55 existing between the adjacent precipitation surfaces 2x as shown in FIG. 8A gradually decreases, and finally the etching surface 55 disappears. The precipitation surfaces 2x facing each other intersect at the back side in the plate thickness direction of the semiconductor substrate 2 (lower side in FIG. 8), and the back surface 2b of the semiconductor substrate 2 is formed only by the precipitation surface 2x.

  By being in such a state, as shown in FIG. 8B and FIG. 2, on the back surface 2b side of the semiconductor substrate 2, an uneven shape by the precipitation surface 2x, that is, a quadrangular pyramid-shaped projection 31 group is formed, An uneven structure 30 is formed. Thus, wet etching with an alkaline solution using the dot-shaped hard mask 54 as a mask is performed on the semiconductor substrate 2 from the (100) plane side, thereby depending on the plane orientation dependence of the semiconductor substrate 2 (111). A large number of quadrangular pyramid shapes (pyramid shapes) formed by the precipitation surface 2x, which is a surface, are deposited as reliefs 31 so as to be embossed, and the concavo-convex structure 30 is formed. In other words, in the manufacturing method of the present embodiment, the semiconductor substrate 2 made of single crystal silicon cut parallel to the (100) plane is processed along the plane orientation of the (111) plane, thereby obtaining a quadrangular pyramid. The concavo-convex structure 30 composed of a group of protrusions 31 having a shape is formed.

  As described above, the manufacturing method according to the present embodiment includes the step of forming the concavo-convex structure 30 by depositing the protrusions 31 by wet etching using the surface orientation dependency of the semiconductor substrate 2. In this step, the semiconductor substrate 2 is etched by wet etching using the hard mask 54 remaining after being selectively removed in the third step as a mask, thereby arranging the semiconductor substrate 2 on the surface of the semiconductor substrate 2 at a predetermined pitch. This corresponds to the fourth step of forming the uneven structure 30 to be performed.

  Then, as shown in FIG. 8C, the hard mask 54 remaining on the semiconductor substrate 2 is removed. In the manufacturing method of the present embodiment, the hard mask 54 is removed by wet etching.

  The necessary characteristics of the chemical used in this wet etching process include, for example, that the hard mask 54 formed as a silicon oxide film can be etched and that there is no etching rate for the single crystal silicon constituting the semiconductor substrate 2. And so on. Specifically, examples of the chemical liquid used in the wet etching process of the hard mask 54 include DHF. Moreover, generally used conditions can be used as the temperature and concentration of the chemical solution in this wet etching step.

By removing the dot-shaped hard mask 54, the concavo-convex structure 30 composed of a group of fine protrusions 31 appears on the back surface 2 b side of the semiconductor substrate 2. Then, the pitch _{p 1} of the sequence of the projections 31 that constitute the uneven structure 30 is equal to the pitch _{p a} resist mask 53 and the hard mask 54.

  Thus, the manufacturing method of this embodiment includes the step of removing the hard mask 54 by wet etching. This step corresponds to a fifth step of removing the hard mask 54 remaining on the semiconductor substrate 2 after forming the concavo-convex structure 30 by the fourth step. After the hard mask 54 is removed in this way, the antireflection film 20 is formed on the back surface 2b of the semiconductor substrate 2 on which the concavo-convex structure 30 is formed.

In the solid-state imaging device 1 obtained by the manufacturing method of the present embodiment as described above, the digging amount of the semiconductor substrate 2 for forming the uneven structure 30, that is, the height h of the uneven structure 30 (see FIG. 8C). ) Is defined by the following equation (1) in relation to the pitch p ₁ (see FIG. 8C) in the arrangement of the protrusions 31 group.
h = (1 / √2) p ₁ (≈0.71 p ₁ ) (1)

The relational expression expressed by the above formula (1) is based on the relationship of the plane orientation of the semiconductor substrate 2 and is derived from the relationship between the (100) plane and the (111) plane in the semiconductor substrate 2. In the concavo-convex structure 30 as the antireflection structure, the value of the pitch p ₁ of the array of the protrusions 31 is preferably such that the incident light is not diffracted, specifically, the wavelength of the incident light or less. Therefore, the value of the pitch p _R of the red projection 31R, the red less desirable wavelengths of light, the value of the pitch p _G of the green projection 31G, the green following desirable wavelength of light, the pitch of the blue projection 31B the value of p _B, the following is desirable wavelength of blue light.

  Thus, by setting the pitch of the array of the protrusions 31 to be equal to or less than the wavelength of the incident light, a desirable requirement for the moth-eye structure in the concavo-convex structure 30 is satisfied, and a light reflection suppressing function can be effectively obtained. The angle formed between the plane 51 as the (100) plane that satisfies the relationship of the above formula (1) and the precipitation surface 2x as the (111) plane is about 54.7 °.

Then, based on the relationship of the equation (1) becomes equal to the value of the pitch p ₁ of the sequence of the projections 31 group, by the pitch p _a between the resist mask 53 in the step of forming a resist mask 53 of dot shape, irregular structure The digging amount of the semiconductor substrate 2 for forming 30, that is, the height h of the concavo-convex structure 30 is determined. That is, by adjusting the pitch p _a between the resist mask 53 can be adjusted final relief structure 30 of the projection 31 group arrangement pitch p size of _1, and the concavo-convex structure 30 height h.

In addition, as described above, for the concavo-convex structure 30 formed using the surface orientation dependency of the semiconductor substrate 2, the height h is determined, and the size (area) of the projection 31 in plan view is also determined. It corresponds to. That is, in the process of the present embodiment, the pitch p _a between the resist mask 53 is determined, the projection including the pitch p ₁ of the sequence of the projections 31 groups, the height and size of the plan view shape of the concavo-convex structure 30 The size of 31 is automatically determined.

  According to the manufacturing method of the present embodiment, when the fine concavo-convex structure 30 for preventing the reflection of incident light is made for each pixel 5, the semiconductor substrate 2 is not damaged, and the reliability and reproducibility are low and low. Can be obtained. The fact that such an effect can be obtained will be specifically described.

  According to the manufacturing method of the present embodiment, the etching for removing the layer structure partially or entirely can be handled only by wet etching. For this reason, it is possible to avoid damage such as crystal defects to the semiconductor substrate 2 that occurs when dry etching using plasma or the like is performed, and a damageless manufacturing method can be realized. As a result, it is possible to prevent a phenomenon that the characteristics of the solid-state imaging device 1 such as white spots and dark current increase due to damage of the semiconductor substrate 2 are deteriorated.

  In the manufacturing method of the present embodiment, the concavo-convex structure 30 is formed by wet etching utilizing the surface orientation dependency of the semiconductor substrate 2 made of single crystal silicon. Therefore, the dot-shaped structure formed in the initial stage of the manufacturing method is used. The height and the like of the concavo-convex structure 30 can be precisely controlled by the resist pattern pitch, and high reliability and reproducibility can be obtained with low cost. Further, the shape of the concavo-convex structure 30 can be accurately reproduced with high reliability without incurring high costs depending on the selection of the chemical used for wet etching and the conditions such as the temperature and concentration of the chemical.

  Furthermore, in the manufacturing method according to the present embodiment, the pitch of the protrusions 31 of the concavo-convex structure 30 is determined by the pitch of the dot-shaped resist pattern. The uneven structure 30 for each pixel 5 can be easily created. For this reason, in the manufacturing method of this embodiment, the reflectance reduction effect is as great as possible for each pixel 5 based on the number of protrusions 31 arranged according to the pitch of the pixels 5 and the combination of the pitches of the protrusions 31 in the concavo-convex structure 30 of each pixel 5. Thus, the pitch of the dot-shaped resist pattern is designed. That is, according to the manufacturing method of the present embodiment, the optimum size of the protrusion 31 corresponding to each color of the pixel 5 is determined so that the reflectance of each pixel 5 is as small as possible, thereby depending on the wavelength of incident light. Thus, the solid-state imaging device 1 having a high antireflection function can be obtained. Thereby, problems such as flare, ghost and blooming caused by reflected light in the solid-state imaging device 1 can be suppressed.

(About the separation structure between pixels)
Next, the formation of the groove 40 as the inter-pixel separation structure in the manufacturing method of the present embodiment will be described. In the manufacturing method of this embodiment, the groove 40 is formed simultaneously with the concavo-convex structure 30 in the process of forming the concavo-convex structure 30 as described above. For this reason, the description overlapping with the content already described will be omitted as appropriate.

  As described above, in the manufacturing method of the present embodiment, first, as shown in FIG. 10A, the hard mask layer 52 is formed on the flat surface 51 of the semiconductor substrate 2. That is, a first step of forming a protective film having an etching selectivity with respect to the semiconductor substrate 2 on the flat surface 51 that is the surface of the semiconductor substrate 2 made of single crystal silicon is performed.

  Next, as shown in FIG. 10B, resist patterning is performed to form a dot-shaped resist mask 53 on the hard mask layer 52. That is, the second step of forming dot-shaped resist patterns arranged at a predetermined pitch on the hard mask layer 52 is performed.

  When forming the groove 40 as the inter-pixel separation structure, in the step of forming this resist pattern, in addition to the dot-shaped resist mask 53 for forming the concavo-convex structure 30 as the antireflection structure, a linear resist is formed. A mask 63 is formed. That is, resist patterning for forming a dot-shaped resist mask 53 and a linear resist mask 63 on the hard mask layer 52 is performed.

  Specifically, as shown in FIG. 9, the linear resist mask 63 is formed in a frame shape along the outer edge of the uneven region 32 of each pixel 5 in parallel with the flat surface 51 of the semiconductor substrate 2. That is, the linear resist mask 63 is formed so as to surround the portion where the concavo-convex structure 30 is provided in each pixel 5 and to border the concavo-convex region 32 partitioned in a rectangular shape. Therefore, as shown in FIG. 9, the linear resist mask 63 includes a pair of horizontal portions 62a arranged in the horizontal direction (horizontal direction) and opposed in the vertical direction (vertical direction) in each pixel 5, and in the vertical direction. It has a pair of vertical portions 62b that are arranged and face each other in the horizontal direction, and these horizontal portions 62a and vertical portions 62b form a rectangular frame shape.

  In this way, the linear resist mask 63 formed in a rectangular shape along the outer edge of the uneven region 32 is arranged along the array of the pixels 5 with a predetermined interval between the adjacent pixels 5. That is, the linear resist mask 63 is arranged along the vertical direction and the horizontal direction in which the plurality of pixels 5 are arranged, and between the pixels 5 adjacent to each other in the vertical direction, between the horizontal portions 62a facing each other in the vertical direction. The pixels 5 that are adjacent to each other in the horizontal direction are arranged at a predetermined interval between the vertical portions 62b that face each other in the horizontal direction.

The interval p _b between the linear resist masks 63 between the pixels 5 adjacent to each other in the vertical direction and the horizontal direction is finally the width (p ₂ ) of the groove 40 as the inter-pixel separation structure formed between the pixels 5. . In other words, the interval p _b between the linear resist masks 63 between the pixels 5 is determined so as to have the same size as the width of the groove 40 formed between the pixels 5. In the solid-state imaging device 1 of the present embodiment, the width dimensions of the groove portions 40 arranged in the vertical direction and the horizontal direction are equal to each other as described above. the spacing between the horizontal portions 62a between the adjacent pixels 5, and the spacing between the vertical portion 62b are both formed of a predetermined interval p _b.

  As described above, in the manufacturing method according to the present embodiment, when forming the groove portion 40 as the inter-pixel separation structure, the second step of forming a resist pattern on the hard mask layer 52 is performed using a dot-shaped resist as the resist pattern. Along with the mask 53, a linear resist mask 63 is formed which is arranged along the array of the pixels 5 with a predetermined interval between the adjacent pixels 5.

  Subsequently, as shown in FIG. 10C, the pattern of the dot-shaped resist mask 53 and the pattern of the linear resist mask 63 are transferred to the hard mask layer 52 by wet etching. That is, in the process of transferring the pattern of the dot-shaped resist mask 53 to the hard mask layer 52 by wet etching as described above, the pattern of the linear resist mask 63 is added to the hard mask layer in addition to the pattern of the dot-shaped resist mask 53. Transferred to layer 52.

  Therefore, in this step, wet etching is performed on the hard mask layer 52 using the dot-shaped resist mask 53 and the linear resist mask 63 formed on the hard mask layer 52 as a mask. As a result, the portion of the hard mask layer 52 corresponding to the dot-shaped resist mask 53 and the portion other than the portion facing the linear resist mask 63 are selectively removed, and the dot-shaped hard mask 54 and the linear The hard mask 64 is formed.

  As described above, in the manufacturing method of the present embodiment, when forming the groove 40 as the inter-pixel isolation structure, the wet etching performed in the third step of selectively removing the hard mask layer 52 is performed in the second step. The dot-shaped resist mask 53 and the linear resist mask 63 which are resist patterns formed by the above are used as masks.

  Next, as shown in FIG. 11A, the semiconductor substrate 2 is processed by wet etching using the dot-shaped hard mask 54 and the linear hard mask 64 as masks, so that the grooves 40 are formed together with the concavo-convex structure 30. Form. That is, on the flat surface 51 of the semiconductor substrate 2, the exposed portion other than the portion covered with the dot-shaped hard mask 54 and the linear hard mask 64 is exposed to a chemical solution for wet etching, whereby the back surface 2 b portion of the semiconductor substrate 2. Is etched to form the concavo-convex structure 30 including the plurality of protrusions 31 and the groove 40 at the same time.

  In the etching process of the semiconductor substrate 2 with the alkaline solution, the concavo-convex structure 30 and the groove 40 are formed in the same process by using the plane orientation dependency of the single crystal silicon constituting the semiconductor substrate 2 as described above. The Therefore, as shown in FIG. 11A, an alkaline solution using a dot-shaped hard mask 54 and a linear hard mask 64 as a mask from a plane 51 which is a (100) plane in a semiconductor substrate 2 made of single crystal silicon. As described above, the etching of the semiconductor substrate 2 proceeds while the precipitation surface 2x as a crystal surface that is difficult to be etched due to the relationship of the plane orientation of the semiconductor substrate 2 is precipitated.

  And when the groove part 40 is formed with the uneven structure 30, in addition to the etching surface 55 which exists in the part in which the uneven structure 30 is formed as an etching progress surface, in the part in which the groove part 40 is formed, the etching surface 55 Similarly, there is an etching surface 65 parallel to the (100) plane (plane 51). The etching surface 65 is formed between the precipitation masks 2x facing in the vertical direction or the horizontal direction between the hard masks 64 opposed in the vertical direction or the horizontal direction between the pixels 5 adjacent in the vertical direction or the horizontal direction.

  Then, as shown in FIG. 11B, when the etching progresses until the deposited surfaces 2x that are deposited between the adjacent hard masks 64 intersect each other, the etching is substantially stopped. That is, as the etching of the semiconductor substrate 2 proceeds, the etching surface 55 and the etching surface 65 existing between the adjacent precipitation surfaces 2x as shown in FIG. 55 and the etching surface 65 disappear and the deposition surfaces 2x facing each other intersect at the back side in the plate thickness direction of the semiconductor substrate 2 (lower side in FIG. 11), and the back surface 2b of the semiconductor substrate 2 is formed only by the deposition surface 2x. It becomes a state.

  In such a state, as shown in FIG. 11B and FIG. 2, as shown in FIG. 11B and FIG. 30 and a groove 40 composed of a pair of inclined surfaces 41 are formed. That is, in the groove portion 40, the slope 41 is formed by the precipitation surface 2x formed by etching with an alkaline solution as described above. As described above, in the manufacturing method of the present embodiment, the semiconductor substrate 2 made of single crystal silicon cut out in parallel to the (100) plane is processed along the plane orientation of the (111) plane, An uneven structure 30 composed of a group of quadrangular pyramidal protrusions 31 and a groove portion 40 formed as a V-shaped groove by a pair of inclined surfaces 41 are simultaneously formed.

  As described above, in the manufacturing method according to the present embodiment, when forming the groove portion 40 as the inter-pixel separation structure, the fourth step of forming the concavo-convex structure 30 by wet etching includes the concavo-convex structure 30 and the adjacent pixels 5. A linear groove 40 is formed at a position corresponding to between the linear resist masks 63 facing each other.

Then, as shown in FIG. 11C, the dot-shaped hard mask 54 and the linear hard mask 64 remaining on the semiconductor substrate 2 are removed by wet etching. By removing these hard masks 54, 64, the concavo-convex structure 30 composed of a group of fine protrusions 31 and the groove 40 formed between the pixels 5 appear on the back surface 2 b side of the semiconductor substrate 2. . The width p _{2 of the} groove 40 is equal to the interval p _b between the resist mask 63 and the hard mask 64 between the adjacent pixels 5.

As described above, the width p _{2 of the} groove portion 40 is basically larger than the pitch p ₁ in the arrangement of the group of protrusions 31 constituting the concavo-convex structure 30. The width p ₂ of the groove 40 is not preferably the same as the wavelength p ₁ of the incident light as in the pitch p ₁ of the projection 31 group of the concavo-convex structure 30, and is set to an appropriate dimension as an inter-pixel separation structure. Is done.

  In addition, as described above, in the solid-state imaging device 1 of the present embodiment, the slope 41 forming the groove 40 is formed as a plane parallel to the surface on which the protrusion 31 of the concavo-convex structure 30 is formed. Is formed by the precipitation surface 2x existing as a crystal plane in the semiconductor substrate 2 made of single crystal silicon, like the protrusion 31 of the concavo-convex structure 30.

As described above, according to the manufacturing method of the present embodiment, the uneven structure 30 serving as the antireflection structure and the inter-pixel separation for suppressing color mixing are performed by one resist patterning such as photolithography and the wet etching process. The groove portion 40 as a structure can be collectively formed on the semiconductor substrate 2 without damage. Further, in the manufacturing method of the present embodiment, the depth d ₁ of the groove 40, that is, the dug of the semiconductor substrate 2 between adjacent pixels, from the viewpoint of suppressing color mixing as described above and the relationship of the plane orientation of the semiconductor substrate 2. The amount is determined to be an appropriate amount based on the sensitivity required in the solid-state imaging device 1 and the color separation performance for obtaining the color mixing prevention effect.

  In the manufacturing method of the present embodiment, the concavo-convex structure 30 as the antireflection structure and the groove portion 40 as the inter-pixel separation structure are simultaneously formed by a common process. However, the process and the groove portion for forming the concavo-convex structure 30 The process for forming 40 may be performed as a different process.

  In addition, the solid-state imaging device 1 of the present embodiment has any one of red (R), green (G), and blue (B) as the color of the pixel 5, that is, the color of the color filter 18. It is not limited to. The solid-state imaging device according to the present technology may include color filters other than RGB including white pixels and the like.

[Second Embodiment]
A second embodiment of the present technology will be described. In addition, about the part which is common in 1st Embodiment including application of a modification, the description is abbreviate | omitted suitably using the same code | symbol. The solid-state imaging device according to this embodiment is different from the solid-state imaging device 1 of the first embodiment in that the uneven structure 30 provided on the back surface 2b side of the semiconductor substrate 2 has a two-layer structure. That is, the concavo-convex structure 30 as the moth-eye structure included in the solid-state image sensor 1 of the first embodiment is a single-layer structure, whereas the moth-eye structure of the solid-state image sensor of the present embodiment is multilayered (double-layered). ing

  As shown in FIG. 12, in the solid-state imaging device 1A of the present embodiment, the antireflection film 20 provided on the back surface 2b of the semiconductor substrate 2 is omitted, and the passivation film 16 is formed on the back surface 2b of the semiconductor substrate 2. Is provided. The solid-state imaging device 1 </ b> A according to the present embodiment includes an intermediate film 50 between the semiconductor substrate 2 and the passivation film 16 provided on the back surface 2 b where the uneven structure 30 is formed on the semiconductor substrate 2. The intermediate film 50 is formed with a uniform film thickness so that the concavo-convex structure 30 formed on the semiconductor substrate 2 has a two-layer structure. Therefore, the intermediate film 50 is uniformly formed following the concave and convex shape formed by the precipitation surface 2x so as to cover the back surface 2b side of the semiconductor substrate 2 as described above.

  In the present embodiment, as shown in FIG. 12, the intermediate film 50 is entirely formed on the back surface 2 b side of the semiconductor substrate 2 including the concavo-convex structure 30 and the groove 40. However, the intermediate film 50 may be provided at least on the portion where the concavo-convex structure 30 is formed on the back surface 2 b side of the semiconductor substrate 2. That is, the intermediate film 50 may be formed so as to cover at least the concavo-convex structure 30 and to form the concavo-convex structure 30 in a two-layer structure with respect to the back surface 2b side of the semiconductor substrate 2.

The intermediate film 50 is made of an intermediate refractive index material between the semiconductor substrate 2 and the passivation film 16. The intermediate film 50 is a film having a refractive index lower than that of the semiconductor substrate 2 and higher than that of the passivation film 16. In the present embodiment, the refractive index of single crystal silicon constituting the semiconductor substrate 2 is about 4, and the refractive index of a silicon oxide film (SiO ₂ film) exemplified as the material of the passivation film 16 is about 1.5. Therefore, the intermediate film 50 is formed of a material having a refractive index that takes a value between these refractive indexes.

Examples of the material of the intermediate film 50 include hafnium oxide (HfO ₂ ), aluminum oxide (Al ₂ O ₃ ), tantalum oxide (Ta ₂ O ₅ ), zirconium oxide (ZrO ₂ ), and titanium oxide (TiO ₂ ). Can be mentioned. The intermediate film 50 may be, for example, a silicon nitride film (SiN film), a silicon oxynitride film (SiON film), a silicon carbonitride film (SiCN film), a carbon-containing silicon oxide film (SiOC film), or a silicon carbide film (SiC). Film) or the like. However, the intermediate film 50 is not limited to those exemplified here, and any known film type can be adopted as long as it is a film made of an intermediate refractive index material as described above. Further, the intermediate film 50 is formed by, for example, a CVD (Chemical Vapor Deposition) method, a sputtering method, an atomic layer deposition method, or the like.

  Thus, in the solid-state imaging device 1A of the present embodiment, the intermediate film 50 made of the intermediate refractive index material is provided between the semiconductor substrate 2 and the passivation film 16, and the concavo-convex structure 30 has a two-layer structure. Yes. In the present embodiment, since the passivation film 16 is provided on the back surface 2 b side where the uneven structure 30 is provided with respect to the semiconductor substrate 2, the intermediate film 50 is provided between the semiconductor substrate 2 and the passivation film 16. However, the layer in which the intermediate film 50 is interposed between the semiconductor substrate 2 and the semiconductor substrate 2 is different depending on the layer structure provided on the back surface 2 b side of the semiconductor substrate 2.

  That is, the intermediate film 50 is the semiconductor substrate 2 and the semiconductor substrate 2 among the films constituting the laminated structure provided on the side where the uneven structure 30 is present with respect to the semiconductor substrate 2, that is, in the case of this embodiment, the back surface 2b side. It is provided between the side films. In the case of the present embodiment, the passivation film 16 is the film closest to the semiconductor substrate 2 among the films constituting the laminated structure provided on the back surface 2 b side of the semiconductor substrate 2. In the case of the modification of the solid-state imaging device 1 (FIG. 6), the film closest to the semiconductor substrate 2 among the films constituting the laminated structure is the color filter layer 17, and the intermediate film 50 is the semiconductor substrate 2. And the color filter layer 17.

[Method for Manufacturing Solid-State Imaging Device]
A method for manufacturing the solid-state imaging device 1A of the present embodiment will be described with reference to FIG. The manufacturing method of the solid-state imaging device 1A of the present embodiment is common to the process of forming the concavo-convex structure 30 and the groove 40 in the semiconductor substrate 2 in the manufacturing method of the first embodiment described above.

  Therefore, as shown in FIG. 13A, in the method for manufacturing the solid-state imaging device 1A, after the step of forming the concavo-convex structure 30 as the antireflection structure and the groove 40 as the interpixel separation structure in the semiconductor substrate 2, A step of removing the hard masks 54 and 64 remaining on the semiconductor substrate 2 is performed. In FIG. 13, only the portion where the uneven structure 30 is provided in the semiconductor substrate 2 is shown.

In the manufacturing method of the solid-state imaging device 1A, after the hard masks 54 and 64 on the semiconductor substrate 2 are removed, as shown in FIG. 13B, the uneven structure 30 and the groove 40 of the semiconductor substrate 2 are formed. A step of forming the intermediate film 50 is performed. As described above, the intermediate film 50 is formed as a hafnium oxide (HfO ₂ ) film, a silicon nitride film (SiN film), or the like from the deposition surface 2x so as to cover the back surface 2b side of the semiconductor substrate 2 by a CVD method or the like. The film is formed with a uniform film thickness following the uneven shape. After the intermediate film 50 is formed on the semiconductor substrate 2, the passivation film 16 is formed on the intermediate film 50 (see FIG. 12).

  As described above, in the method of manufacturing the solid-state imaging device 1A according to the present embodiment, after removing the hard masks 54 and 64 by wet etching, the intermediate film 50 is formed at least on the uneven structure 30 portion on the back surface 2b side of the semiconductor substrate 2. The process of carrying out is included. That is, in the manufacturing method of the solid-state imaging device 1A of the present embodiment, the refractive index of the semiconductor substrate 2 is formed on the surface (back surface 2b) on the side where the uneven structure 30 of the semiconductor substrate 2 is formed after the above-described fifth step. And an intermediate film 50 having a refractive index higher than the refractive index of the passivation film 16 which is the film on the semiconductor substrate 2 side among the films constituting the laminated structure provided on the back surface 2b side with respect to the semiconductor substrate 2. A sixth step of forming is further included.

  According to the solid-state imaging device 1A of the present embodiment, the antireflection performance by the concavo-convex structure 30 can be improved. In other words, the same antireflection effect can be obtained even when the height of the concavo-convex structure 30 is low in comparison with the single-layer structure of the concavo-convex structure 30 that does not include the intermediate film 50. Thereby, according to 1 A of solid-state image sensors of this embodiment, the layer structure which has the uneven structure 30 can be reduced in height. Lowering the layer structure leads to suppression of color mixing in the solid-state imaging device 1A.

The intermediate film 50 formed on the back surface 2b side of the semiconductor substrate 2 can also be formed as a film having a negative fixed charge. Also in this case, the intermediate film 50 includes, for example, hafnium oxide (HfO ₂ ), aluminum oxide (Al ₂ O ₃ ), tantalum oxide (Ta ₂ O ₅ ), zirconium oxide (ZrO ₂ ), titanium oxide (TiO ₂ ), and the like. These materials are used, and a film is formed by a CVD method or the like. In this way, by forming the intermediate film 50 as a film having a negative fixed charge, the following effects can be obtained.

A natural oxide film may be formed on the surface of the semiconductor substrate 2 in the manufacturing process of the solid-state imaging device 1A. In this case, the natural oxide film formed on the surface of the semiconductor substrate 2 is formed by reacting single crystal silicon with oxygen in the atmosphere, and becomes a SiO ₂ film. Thus, when the SiO ₂ film as a natural oxide film is formed on the surface of the semiconductor substrate 2, the intermediate film 50 exists with respect to the semiconductor substrate 2 via the SiO ₂ film.

As described above, in the configuration in which the intermediate film 50 exists on the semiconductor substrate 2 through the natural oxide film, when the intermediate film 50 is a film having a negative fixed charge, it is between the semiconductor substrate 2 and the intermediate film 50. The natural oxide film functions as a film that lowers the interface state. Specifically, the photodiode 6 is configured in the semiconductor substrate 2 through the SiO ₂ film, which is a natural oxide film, by the negative fixed charge in the film of the intermediate film 50 as a film having a negative fixed charge. An electric field is applied to the surface of the light receiving portion. When an electric field is applied to the surface of the light receiving portion, holes (holes) are induced on the surface of the light receiving portion, and a pinning layer that accumulates holes is formed between the light receiving portion and the natural oxide film.

  As a result, dark current generated by the interface state at the interface between the light receiving portion formed on the semiconductor substrate 2 and the natural oxide film functioning as a film that lowers the interface state is suppressed. Specifically, electrons generated from the interface between the light receiving portion and the natural oxide film are suppressed, and the electrons generated from the interface disappear by flow in the pinning layer in which many holes exist. For this reason, since the dark current due to the electrons generated from the interface between the light receiving portion and the natural oxide film is prevented from being detected by the light receiving portion, the dark current due to the interface state is suppressed.

  Thus, in the solid-state imaging device 1A of the present embodiment, by forming the intermediate film 50 as a film having a negative fixed charge, an effect of suppressing dark current can be obtained in addition to the effect of antireflection. . Since the dark current causes a so-called white spot, the suppression of the dark current can suppress the white spot.

  Further, in the configuration in which the intermediate film 50 covering the concavo-convex structure 30 formed on the semiconductor substrate 2 is provided as in the solid-state imaging device 1A of the present embodiment and the moth-eye structure is doubled, the semiconductor substrate 2 and the passivation are provided. An antireflection effect can be obtained not only between the film 16 but also at the interface between the intermediate film 50 and the passivation film 16.

Also, when the SiO ₂ film is present as a natural oxide film on the surface of the semiconductor substrate 2 as described above, SiO ₂ film, uneven shape formed on the back surface 2b side of the semiconductor substrate 2, that is formed by the deposition surface 2x It is formed following the shape of the concavo-convex structure 30 and the groove 40. Accordingly, the intermediate film 50 is entirely formed on the surface on the back surface 2b side of the semiconductor substrate 2 by a CVD method or the like in the state where the SiO ₂ film exists as a natural oxide film on the surface of the semiconductor substrate 2, thereby forming the semiconductor. The shape of the laminated structure of the substrate 2 and the natural oxide film can be transferred to the laminated structure of the natural oxide film and the intermediate film 50.

[simulation result]
The following simulation results are obtained for the solid-state imaging device according to the above-described embodiment. FIG. 14 shows a simulation result about the effect of the solid-state imaging device 1A of the second embodiment. FIG. 14 shows a simulation result of a change in average reflectance (%) with respect to a change in pitch (nm) of the concavo-convex structure 30 and a height of the concavo-convex structure 30 (height of the protrusion 31) (nm).

  FIG. 14A shows the result when the concavo-convex structure 30 has a single-layer structure as in the solid-state imaging device 1 of the first embodiment. As shown in FIG. 15A, a semiconductor substrate made of single-crystal silicon. The reflectance between the two concavo-convex structures 30 and the air layer 57 is measured. FIG. 14B shows the result when the intermediate film 50 is provided as in the solid-state imaging device 1A of the second embodiment and the concavo-convex structure 30 has a two-layer structure. As shown in FIG. The reflectance between the air layer 57 in a structure in which a silicon nitride film (SiN film) is provided as the intermediate film 50 on the uneven structure 30 of the semiconductor substrate 2 made of crystalline silicon is measured. The refractive index in the air layer 57 is about 1. In the simulation results shown in FIGS. 14 (a) and 14 (b), the range of 0 to 30% is expressed in 15 stages from r1 to r15 with respect to the average reflectance (%).

  As can be seen from FIGS. 14A and 14B, regardless of whether the concavo-convex structure 30 is a single-layer structure or a two-layer structure, the average reflectance tends to decrease as the height of the concavo-convex structure 30 increases. On the other hand, regarding the pitch of the concavo-convex structure 30, as shown in FIG. 14A, when the concavo-convex structure 30 has a single layer structure, the average reflectance tends to increase as the pitch increases.

  According to the simulation result, the reflectance is greatly reduced by changing the concavo-convex structure 30 from a single-layer structure to a two-layer structure. Specifically, as shown in FIGS. 14A and 14B, in the height range (50 to 750 nm) of the concavo-convex structure 30 shown in FIG. Depending on the size, the average reflectance has increased to 30% (see FIG. 14A), but when the concavo-convex structure 30 has a two-layer structure, the average reflectance is 10% regardless of the pitch size. It is as follows (see FIG. 14B). As described above, as a simulation result, by adopting a two-layer structure for the concavo-convex structure 30, a result that the antireflection effect is significantly improved as compared with the case where the concavo-convex structure 30 is a single-layer structure is obtained. .

  FIG. 16 shows a simulation result on the wavelength dependence of the concavo-convex structure 30 included in the solid-state imaging device 1 of the above-described embodiment. FIG. 16 shows a simulation result on the wavelength dependence of the relationship between the pitch (nm) of the concavo-convex structure 30 and the reflectance.

  In this simulation, the blue spectrum (wavelength 450 ± 50 nm) in the blue pixel 5B, the green spectrum (wavelength 530 ± 50 nm) in the green pixel 5G, and the red spectrum (wavelength 620 ± 50 nm) in the red pixel 5R are used as the incident light. In the case where the concavo-convex structure 30 is formed on the semiconductor substrate 2 by determining the pitch (nm) of the concavo-convex structure 30 so that the height of the concavo-convex structure 30 becomes a value every 50 nm in the range of 50 to 450 nm for each wavelength. The behavior of the reflectance is shown. In this simulation, the pitch when the height of the concavo-convex structure 30 is 50 nm is 70 nm, and the pitch increases by 70 nm every time the height increases by 50 nm. In the graph shown in FIG. 16, the measurement point is a diamond-shaped solid line graph S1 indicates the case of the blue pixel 5B, the measurement point is a square dot-and-dash line graph S2 is the green pixel 5G, and the measurement point is a circle. A broken line graph S3 indicates the case of the red pixel 5R.

  In FIG. 16, in the case of the blue pixel 5B shown in the graph S1 and the case of the green pixel 5G shown in the graph S2, the reflectance reduction effect tends to increase as the pitch of the uneven structure 30 increases. As described above, in the case where the effect of reducing the reflectance is greater as the pitch of the uneven structure 30 is larger, it is desirable to adopt a structure having a relatively large pitch as the uneven structure 30.

  Therefore, in the case of the blue pixel 5B and the green pixel 5G, for example, the largest value of 630 nm is adopted as the pitch of the concavo-convex structure 30 in this simulation. On the other hand, in each pixel 5, it is desirable to cover the protrusions 31 of the uneven structure 30 as much as possible. Therefore, when the pitch of the concavo-convex structure 30 is larger as in the case of the blue pixel 5B and the green pixel 5G, the effect of reducing the reflectance is larger, the concavo-convex structure 30 having the largest possible pitch is arranged, and as a result, the concavo-convex structure 30 When the flat portion remains between the region provided with the groove portion 40 as the inter-pixel separation structure, the uneven structure 30 with a reduced pitch is formed in the flat portion, thereby laying the uneven structure 30 in each pixel 5. It is desirable. By adopting such a method, it is possible to obtain a high reflectance reduction effect in the main part of the pixel 5 and also to obtain an antireflection effect by the uneven structure 30 in the peripheral part of the pixel 5. 5 can improve the overall antireflection function.

  In FIG. 16, in the case of the red pixel 5 </ b> R shown by the graph S <b> 3, the reflectance reduction effect is almost constant when the pitch of the concavo-convex structure 30 is 210 nm or more. As described above, when the effect of reducing the reflectance is almost constant regardless of the value of the concavo-convex structure 30, more protrusions are formed in the concavo-convex area 32 including the light receiving part which is the main part of the pixel 5 as the pitch of the concavo-convex structure 30. It is desirable to employ a pitch that can form 31. In this case, for example, the smallest value of 70 nm is adopted as the pitch of the uneven structure 30 in this simulation.

  As can be seen from the simulation results, at least in the reflectance range (0 to 0.1) in the simulation results shown in FIG. 16, the relationship between the pitch of the concavo-convex structure 30 and the reflectance has wavelength dependency. That is, the relationship between the pitch of the concavo-convex structure 30 and the reflectance is not unique regardless of the color of the incident light, that is, the wavelength, and varies depending on the wavelength of the incident light.

  The wavelength dependence of the relationship between the pitch and the reflectance of the concavo-convex structure 30 changes based on the thickness, material, refractive index, and the like of each layer in the stacked structure on the semiconductor substrate 2. Therefore, as in the solid-state imaging device 1 of the above-described embodiment, a configuration in which the pitch of the concavo-convex structure 30 is changed for each color of the pixel 5, and based on the thickness of each layer of the stacked structure on the semiconductor substrate 2, etc. By determining the optimum size of the protrusion 31 corresponding to each color of the pixel 5 so that the reflectance becomes as small as possible in each pixel 5, an antireflection effect independent of the wavelength of incident light can be obtained. .

[Configuration example of electronic equipment]
The solid-state imaging device according to each of the above-described embodiments is applied to various electronic devices such as a digital still camera called a digital camera, a digital video camera, a mobile device such as a mobile phone having an imaging function, and other devices. Applied. Below, the video camera 100 which is an example of an electronic device provided with the solid-state image sensor which concerns on embodiment mentioned above is demonstrated using FIG.

  The video camera 100 captures still images or moving images. The video camera 100 includes the solid-state imaging device 101 according to the above-described embodiment, an optical system 102, a shutter device 103, a drive circuit 104, and a signal processing circuit 105.

  The optical system 102 is configured as an optical lens system having, for example, one or a plurality of optical lenses, and guides incident light to the light receiving unit of the solid-state imaging device 101. The optical system 102 forms image light (incident light) from the subject on the imaging surface of the solid-state imaging device 101. As a result, signal charges are accumulated in the solid-state imaging device 101 for a certain period. The shutter device 103 is configured to control the light irradiation period and the light shielding period to the solid-state image sensor 101.

  The drive circuit 104 drives the solid-state image sensor 101 and the shutter device 103. The drive circuit 104 generates a drive signal (timing signal) for driving the solid-state image sensor 101 at a predetermined timing, and supplies the drive signal to the solid-state image sensor 101. The transfer operation of the signal electrodes of the solid-state image sensor 101 is controlled by a drive signal supplied from the drive circuit 104 to the solid-state image sensor 101. That is, the solid-state imaging device 101 performs a signal charge transfer operation or the like by the drive signal supplied from the drive circuit 104.

  The drive circuit 104 has a function of generating various pulse signals as drive signals for driving the solid-state image sensor 101, and a driver that converts the generated pulse signals into drive pulses for driving the solid-state image sensor 101. With functions. The drive circuit 104 also generates and supplies a drive signal for controlling the operation of the shutter device 103.

  The signal processing circuit 105 has a function of performing various signal processing, and processes an output signal of the solid-state imaging device 101. The signal processing circuit 105 processes the input signal to output a video signal. The video signal output from the signal processing circuit 105 is stored in a storage medium such as a memory or output to a monitor. Note that the video camera 100 includes a power supply unit such as a battery that supplies power to the drive circuit 104 and the like, a storage unit that stores a video signal generated by imaging, a control unit that controls the entire apparatus, and the like.

  Note that the video camera 100 according to the present embodiment includes a camera module in which a solid-state imaging device 101, an optical system 102, a shutter device 103, a drive circuit 104, and a signal processing circuit 105 are modularized for mobile devices or the like. The form of an imaging function module is also included.

  According to the video camera 100 having the solid-state imaging device 101 of the present embodiment having the above-described configuration, the anti-reflection function can be obtained in the solid-state imaging device 101 without depending on the wavelength of incident light. Since phenomena and color mixing caused by incident light reflection such as ghost and blooming can be suppressed, image quality can be improved.

In addition, this technique can take the following structures.
(1) A first step of forming a protective film having an etching selectivity with respect to the semiconductor substrate on the surface of a semiconductor substrate made of a single crystal, and a dot shape arranged on the protective film at a predetermined pitch A second step of forming the resist pattern, a third step of selectively removing the protective film by wet etching using the resist pattern formed in the second step as a mask, and the third step of By etching the semiconductor substrate by wet etching using the protective film remaining after being selectively removed in the process as a mask, a concavo-convex structure arranged at the predetermined pitch is formed on the surface of the semiconductor substrate. And a fifth step of removing the protective film remaining on the semiconductor substrate after forming the concavo-convex structure by the fourth step, Including, method of manufacturing a solid-state imaging device.

  (2) In the solid-state imaging device according to (1), in the second step, the dot-shaped resist pattern is arranged at a predetermined pitch for each pixel arranged in the pixel region on the semiconductor substrate. Production method.

(3) The second step forms, together with the dot-shaped resist pattern, a linear resist pattern arranged along the array of the pixels with a predetermined interval between the adjacent pixels,
In the fourth step, linear grooves are formed in the corresponding positions between the linear resist patterns facing each other between the adjacent pixels together with the concavo-convex structure, (1) or ( A method for producing a solid-state imaging device according to 2).

  (4) After the fifth step, the concavo-convex structure is formed on the surface of the semiconductor substrate on the side where the concavo-convex structure is formed, which is lower than the refractive index of the semiconductor substrate and the semiconductor substrate. (1) to (3), further including a sixth step of forming an intermediate film having a refractive index higher than a refractive index of the film on the semiconductor substrate side among the films constituting the laminated structure provided on the opposite side. The manufacturing method of the solid-state image sensor in any one of.

  (5) A semiconductor substrate made of a single crystal and having a pixel region in which a plurality of pixels including a light receiving portion having a photoelectric conversion function are arranged; and on the side where light received by the light receiving portion of the semiconductor substrate is incident A color filter provided for each pixel, and the semiconductor substrate has a concavo-convex structure with fine pyramidal protrusions arranged at a predetermined pitch for each pixel on the surface on which the light is incident. Solid-state image sensor.

  (6) The solid-state imaging device according to (5), wherein the semiconductor substrate has a linear groove portion having a surface parallel to a surface on which the pyramidal protrusion is formed, between the adjacent pixels.

  (7) The refraction of the semiconductor substrate is provided between the semiconductor substrate and a film on the most side of the semiconductor substrate among the films constituting the stacked structure provided on the side where the uneven structure exists with respect to the semiconductor substrate. The solid-state imaging device according to (5) or (6), further including an intermediate film having a refractive index lower than the refractive index and higher than the refractive index of the film closest to the semiconductor substrate.

  (8) A solid-state image sensor, an optical system that guides incident light to a light receiving unit of the solid-state image sensor, a drive circuit that generates a drive signal for driving the solid-state image sensor, and an output signal of the solid-state image sensor A signal processing circuit for processing, wherein the solid-state imaging device is made of a single crystal and has a pixel region in which a plurality of pixels including a light receiving unit having a photoelectric conversion function are arranged, and the semiconductor substrate A color filter provided for each of the pixels on the side on which light received by the light receiving unit is incident, and the semiconductor substrate is arranged on the surface on the side on which the light is incident at a predetermined pitch for each of the pixels. An electronic device having a concavo-convex structure formed by fine pyramidal protrusions.

DESCRIPTION OF SYMBOLS 1 Solid-state image sensor 1A Solid-state image sensor 2 Semiconductor substrate 2b Back surface 2x Precipitation surface 3 Pixel area 5 Pixel 6 Photodiode (light-receiving part)
16 Passivation film 18 Color filter 30 Concave and convex structure 31 Protrusion 40 Groove part 41 Slope 50 Intermediate film 51 Plane (surface of semiconductor substrate)
52 Hard mask layer (protective film)
53 Resist mask (dot-shaped resist pattern)
54 Hard mask 63 Resist mask (Linear resist pattern)
64 Hard mask 100 Video camera (electronic equipment)
102 optical system 104 drive circuit 105 signal processing circuit

Claims (8)

A first step of forming a protective film having an etching selectivity with respect to the semiconductor substrate on the surface of the semiconductor substrate made of a single crystal;
A second step of forming dot-shaped resist patterns arranged at a predetermined pitch on the protective film;
A third step of selectively removing the protective film by wet etching using the resist pattern formed in the second step as a mask;
The semiconductor substrate is etched by wet etching using the protective film remaining after being selectively removed in the third step as a mask, so that the semiconductor substrate is arranged on the surface of the semiconductor substrate at the predetermined pitch. A fourth step of forming an uneven structure;
A fifth step of removing the protective film remaining on the semiconductor substrate after forming the concavo-convex structure by the fourth step.
Manufacturing method of solid-state image sensor. In the second step, the dot-shaped resist pattern is arranged at a predetermined pitch for each pixel arranged in the pixel region on the semiconductor substrate.
The manufacturing method of the solid-state image sensor of Claim 1. The second step forms, together with the dot-shaped resist pattern, a linear resist pattern arranged along the pixel array with a predetermined interval between the pixels adjacent to each other.
In the fourth step, linear grooves are formed at positions corresponding to the linear resist patterns facing each other between the adjacent pixels together with the concavo-convex structure.
The manufacturing method of the solid-state image sensor of Claim 1. After the fifth step, the surface of the semiconductor substrate on the side where the uneven structure is formed is lower than the refractive index of the semiconductor substrate and on the side where the uneven structure is formed with respect to the semiconductor substrate. A sixth step of forming an intermediate film having a refractive index higher than the refractive index of the film on the semiconductor substrate side among the films constituting the laminated structure provided;
The manufacturing method of the solid-state image sensor of Claim 1. A semiconductor substrate made of a single crystal and having a pixel region in which a plurality of pixels including a light receiving portion having a photoelectric conversion function are arranged;
A color filter provided for each pixel on a side on which light received by the light receiving portion of the semiconductor substrate is incident;
The semiconductor substrate has a concavo-convex structure with fine pyramidal projections arranged at a predetermined pitch for each pixel on the surface on which the light is incident.
Solid-state image sensor. The semiconductor substrate has a linear groove formed of a surface parallel to a surface forming the pyramidal projection between the pixels adjacent to each other.
The solid-state imaging device according to claim 5. Provided between the semiconductor substrate and the film on the side of the semiconductor substrate that is closest to the semiconductor substrate among the films that constitute the stacked structure provided on the side where the uneven structure exists with respect to the semiconductor substrate, and more than the refractive index of the semiconductor substrate An intermediate film having a refractive index lower than that of the film closest to the semiconductor substrate;
The solid-state imaging device according to claim 5. A solid-state image sensor;
An optical system that guides incident light to the light receiving portion of the solid-state imaging device;
A drive circuit for generating a drive signal for driving the solid-state imaging device;
A signal processing circuit for processing an output signal of the solid-state imaging device,
The solid-state imaging device is
A semiconductor substrate made of a single crystal and having a pixel region in which a plurality of pixels including a light receiving portion having a photoelectric conversion function are arranged;
A color filter provided for each pixel on a side on which light received by the light receiving portion of the semiconductor substrate is incident;
The semiconductor substrate has a concavo-convex structure with fine pyramidal projections arranged at a predetermined pitch for each pixel on the surface on which the light is incident.
Electronics.

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