JP2008091771A - Solid-state image pickup device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid-state image pickup device with a high reliability, in which a condensing efficiency to a photoelectric conversion device is high and a smear component and a color mixing between adjoining photoelectric conversion devices are few. <P>SOLUTION: There is provided an optical waveguide 18 constituted by a first transparent film 19 and a second transparent film 20 by inserting an insulating film 13 and an etching stopper film 17 to an upper part of a photoelectric conversion device 12. A refractive index of the first transparent film 19 is lower than that of the second transparent film 20. Further, there is provided a condenser lens 21 integrated with the second transparent film 20. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a CCD type solid-state imaging device including a photoelectric conversion element and a method for manufacturing the same.

  In recent years, solid-state imaging devices have been widely used in digital cameras, mobile phones with a photographic function, and the like. As these devices become smaller and more functional, solid-state imaging devices used in the devices are also required to have more pixels and improve sensitivity. In particular, as the number of pixels is increased, the size of one element (pixel pitch) is reduced, so that the area of the opening of the photoelectric conversion element is reduced and the amount of light incident on the photoelectric conversion element is reduced. Has become a problem, and the S / N (signal / noise) ratio has deteriorated, and a technique for efficiently incorporating incident light into a photoelectric conversion element is required.

  In order to realize this, a solid-state imaging device has been proposed in which an on-chip microlens or a condensing lens is provided above the photoelectric conversion element to improve the condensing efficiency (see, for example, Patent Document 1).

  A specific structure of a conventional solid-state imaging device having two lenses such as an on-chip microlens and a condenser lens will be described with reference to FIG. FIG. 15 is a cross-sectional view showing the structure of a conventional solid-state imaging device.

  In the figure, a photoelectric conversion element 107 and a charge transfer unit 106 which are light receiving units are provided on a surface layer portion of a semiconductor substrate 105. A transfer electrode 104 and a light shielding film 103 covering the transfer electrode 104 are provided on the charge transfer unit 106. The photoelectric conversion element 107 and the light-shielding film 103 are covered with the first planarization layer 109, and the first light condensing portion is located above the photoelectric conversion element 107 on the first planarization layer 109. A condensing lens 108 is provided. A second flattening layer 102 is provided on the first flattening layer 109 and the condensing lens 108, and the second condensing portion is turned on on the second flattening layer 102. A chip microlens 101 is provided.

  In this structure, the refractive index of the on-chip microlens 101 is n1, the refractive index of the second planarizing layer 102 is n2, the refractive index of the condenser lens 108 is n3, and the refractive index of the first planarizing layer 109 is n4. Then, n1≈n2 <n3≈n4.

  However, in the conventional solid-state imaging device thus obtained, when the incident light refracted by the condenser lens 101 is vertically incident, it is condensed on the photoelectric conversion element 107 as shown by the solid line in FIG. However, when incident light is incident obliquely, the light may not be condensed on the photoelectric conversion element 107 as indicated by the dotted line in FIG. In this case, since the efficiency of condensing on the photoelectric conversion element is reduced, the image becomes dark. Further, when obliquely incident light is reflected on the light shielding film 103 and a part thereof enters the adjacent photoelectric conversion element 107, color mixing (crosstalk) is caused and image quality is deteriorated.

  Therefore, a solid-state imaging device having a condensing function instead of a condensing lens has been proposed as a solid-state imaging device with improved condensing efficiency. A specific structure of such a solid-state imaging device will be described with reference to FIG.

  FIG. 16 is a cross-sectional view showing a solid-state imaging device according to a second conventional example. In this solid-state imaging device, the surface layer portion of the silicon substrate 202 includes a photoelectric conversion element 203 that is a light receiving portion, a read gate 204 adjacent to one end of the photoelectric conversion element 203, and a charge transfer unit 205 adjacent to the read gate 204. A channel stop 206 adjacent to the other end of the photoelectric conversion element 203 is provided. The silicon substrate 202 is covered with an insulating film 207, and a transfer electrode 208 is provided on the charge transfer unit 205 with the insulating film 207 interposed therebetween. An interlayer insulating film 209 is provided on a part of the upper surface of the insulating film 207 and on the upper surface and side surfaces of the transfer electrode 208, and a portion of the interlayer insulating film 209 located above the transfer electrode 208 is covered with the light shielding film 210. It has been broken. A planarization layer 212 is provided on the light shielding film 210.

  An opening 211 formed by removing the planarization layer 212 and the light shielding film 210 is provided on the photoelectric conversion element 203. Inside the opening 211, there are a first transparent film 214 that covers the bottom and side surfaces of the opening 211, a second transparent film 215 that covers the inner surface of the first transparent film 214, and a second transparent film. A third transparent film 216 that covers the inner surface of 215 and fills the opening 211 is provided. A passivation film 217 and a color filter layer 218 are provided in this order on the planarizing layer 212 and on the top surfaces of the first transparent film 214, the second transparent film 215, and the third transparent film 216, and the color filter layer 218. On-chip microlens 219 is provided on the top.

  In this structure, the refractive index of the first transparent film 214 is n1, the refractive index of the second transparent film 215 is n2, the refractive index of the third transparent film 216 is n3, and the refractive index of the planarizing layer 212 is n4. Then, n1> n2> n3> n4. With this configuration, the light collection efficiency to the light receiving unit is enhanced (for example, see Patent Document 2).

  Further, there has been proposed an optical waveguide having an improved embedding property by combining an inorganic material such as a silicon nitride film and an organic material such as polyimide in the above optical waveguide. FIG. 17 is a cross-sectional view showing the structure of a solid-state imaging device according to a third conventional example using an optical waveguide in which such an inorganic material and an organic material are combined (see, for example, Patent Document 3).

In FIG. 17, a photoelectric conversion element 250 and a transfer gate 251 are formed in the surface layer portion of the semiconductor silicon substrate. A transfer electrode 253 for controlling the transfer gate 251 is formed on the upper surface of the semiconductor substrate via a gate insulating film 252, and an etching stopper film made of silicon nitride is formed on the transfer electrode 253 via an insulating film 254. 255 is provided. Further, a plurality of layers of wirings 256 and an interlayer insulating film 257 are provided on the etching stopper film 255. A conductive plug 258 is provided between each wiring 256 and the contact region of the semiconductor substrate, and the wiring 256 in each layer is connected. Further, a passivation film 260 is provided on the uppermost insulating film 259, and a color filter 262 and a microlens 263 are provided on the passivation film 260 via a planarizing film 261. A hole is formed in the insulating film 259 from the uppermost surface to the insulating film on the light receiving region of the photoelectric conversion element 250, and an optical waveguide 264 is provided so as to be embedded in the hole. The optical waveguide 264 is composed of a first optical waveguide 264a made of plasma silicon nitride on the outside and a second optical waveguide 264b made of polyimide resin embedded in a cavity in the first optical waveguide 264a. ing.
Japanese Patent No. 2956132 Japanese Patent Laid-Open No. 11-121725 JP 2004-207433 A JP 2000-150845 A

  However, in the solid-state imaging device according to the second conventional example shown in FIG. 16, the first transparent film 214, the second transparent film 215, and the third transparent film are formed in the hole provided above the photoelectric conversion element 203. When the transparent films 216 are sequentially formed, the cross-sectional area of the upper part of the hole serving as the gas inlet gradually decreases. Therefore, it is difficult for the raw material gas to enter the hole 213, and voids (voids) are easily generated. Since the inside of the void is vacuum or air, scattered light is generated due to the void and the sensitivity is lowered.

  Furthermore, since the optical waveguides from the first transparent film 214 to the third transparent film 216 are composed of laminated films formed of different materials, due to differences in linear expansion coefficient, internal stress generated during film formation, and the like In some cases, a large stress is generated in the solid-state imaging device, causing cracks or peeling.

  Further, stress is also applied to the photoelectric conversion element, and white scratches, which are noise components when an image is displayed, are generated. Furthermore, there has been a problem such as an increase in the number of steps for forming the laminated film, resulting in a decrease in manufacturing yield.

  Further, in the solid-state imaging device shown in FIG. 17, in order to prevent the generation of voids, a first optical waveguide portion made of outer plasma silicon nitride and a cavity in the first optical waveguide portion are embedded in the hole portion. An optical waveguide composed of a second optical waveguide portion made of polyimide resin embedded in the portion is formed. However, when the pixel pitch is smaller than 2 μm, for example, the diameter of the portion where the optical waveguide can be formed is greatly estimated. Even if it becomes 1 micrometer or less. Therefore, the film thickness of the first optical waveguide portion made of plasma silicon nitride having a high refractive index outside the optical waveguide is as thin as about 250 nm, for example. As a result, the film thickness of the first optical waveguide portion becomes smaller than the wavelength of light, light does not enter the waveguide, and the light collection efficiency of incident light on the photoelectric conversion element may be reduced.

  Further, in the first and second solid-state imaging devices shown in FIGS. 16 and 17, a silicon oxide thin film as an insulating film is provided on the upper surface of the photoelectric conversion element, and the outermost layer of the optical waveguide is formed thereon. Therefore, the silicon substrate (refractive index = 4.2) / silicon oxide thin film (refractive index = 1.45) / silicon nitride film (refractive index = 2.0) is used. Therefore, no matter how the thickness of the silicon oxide thin film is changed, it is difficult to reduce the reflectance of incident light on the silicon substrate surface, and a part of the light collected by the optical waveguide is reflected on the substrate surface. As a result, the light collection efficiency to the photoelectric conversion element may be reduced.

  The present invention is intended to solve the above-mentioned conventional problems, has high light collection efficiency to the photoelectric conversion element, has little smear component, and less color mixture (crosstalk) between adjacent photoelectric conversion elements, and the surface of the photoelectric conversion element An object of the present invention is to provide a solid-state imaging device that has a low reflectance of incident light and can suppress the occurrence of white scratches, which are noise components when an image is displayed, and a manufacturing method thereof.

  A solid-state imaging device of the present invention includes a plurality of photoelectric conversion elements provided in a semiconductor substrate, an insulating film provided on the semiconductor substrate, an etching stopper film provided on the insulating film, A transfer electrode provided on the insulating film and on a side of the photoelectric conversion element, a hole provided on the etching stopper film and above the transfer electrode, and above each of the plurality of photoelectric conversion elements Formed between the interlayer insulating film, the first transparent film provided above the photoelectric conversion elements along the inner wall of the hole, and the hole provided on the first transparent film. An optical waveguide having a second transparent film that fills, and a condensing lens that is formed of the same material as the second transparent film and is disposed from above the optical waveguide to above the interlayer insulating film. The first transparent film and the second transparent film Any spare refractive index of the condenser lens is higher than the interlayer insulating film, and the refractive index of the first transparent film is lower than the refractive index of the second transparent film and the condenser lens.

With this configuration, light incident at an angle perpendicular to the substrate surface is refracted by the condenser lens, enters the optical waveguide, is condensed on the photoelectric conversion element below, and is inclined with respect to the substrate surface. Light incident at an angle (obliquely incident light) is also refracted by the condensing lens and then totally reflected by the side surface of the optical waveguide, thereby confining in the optical waveguide and condensing on the photoelectric conversion element below.
As described above, since it is possible to condense even the oblique incident light having a large angle, which cannot be collected with the configuration without the conventional optical waveguide, on the photoelectric conversion element, the light collection efficiency is improved. Furthermore, the light confinement effect of the optical waveguide makes it difficult for obliquely incident light to leak out to the transfer electrode and the like, so that smear components can be reduced and incident light does not easily propagate to adjacent pixels. Talk) can be prevented.

  The first transparent film of the optical waveguide has a refractive index larger than the refractive index of the interlayer insulating film and smaller than the refractive index of the second transparent film of the optical waveguide; It is preferably at least one of magnesium oxide and silicon oxynitride. Further, in the first transparent film of the optical waveguide, it is preferable that the film thickness of the portion on the side wall of the hole portion of the interlayer insulating film is smaller than the film thickness of the bottom surface portion of the hole portion in contact with the etching stopper film. . With this configuration, the film configuration from the silicon substrate on which the photoelectric conversion element is formed to the optical waveguide is, for example, a silicon substrate (refractive index = 4.2) / silicon oxide thin film (refractive index = 1.45) / silicon nitride film. (Refractive index = 2.0) / silicon oxynitride film (refractive index = 1.6) / silicon nitride film (refractive index = 2.0). In addition, by appropriately optimizing the thickness of each thin film, an antireflection laminated film can be formed as a whole, and the reflectance of incident light on the silicon substrate can be set to a low value. As a result, the light collection efficiency of light incident on the photoelectric conversion element can be increased. Furthermore, by making the film thickness of the hole side wall portion in contact with the interlayer insulating film in the first transparent layer smaller than the film thickness of the hole bottom surface portion in contact with the etching stopper film, Since the cross-sectional area of the transparent film can be increased, even when the pixel pitch is reduced, incident light can be taken into the high refractive index portion inside the optical waveguide, and the incident light is efficiently guided to the photoelectric conversion element. be able to. At the same time, since the cross-sectional area of the second transparent film is large, it is possible to prevent the generation of voids (voids) during the formation of the second transparent film, and to prevent the sensitivity of incident light from decreasing. Furthermore, since the optical waveguide has a two-layer structure of the first transparent film and the second transparent film, the number of manufacturing steps can be reduced and the yield can be improved as compared with the example shown in Patent Document 2.

  The second transparent film of the optical waveguide and the condenser lens have a higher refractive index than that of the first transparent film of the optical waveguide, and contain titanium oxide containing hydrogen (refractive index of 2.2 to 2.5). ), Tantalum oxide (refractive index 2.0-2.3), niobium oxide (refractive index 2.0-2.3), tungsten oxide (refractive index 2.2), zirconium oxide (refractive index 2.05), Among zinc oxide (refractive index 2.0), indium oxide (refractive index 2.0), hafnium oxide (refractive index 2.0 to 2.1), and silicon nitride (refractive index 1.8 to 2.0) Preferably, the interlayer insulating film is made of a material having a refractive index of 1.5 or less and having silicon oxide as a main component. Thus, by using a material having a high refractive index for the second transparent film and the condenser lens of the optical waveguide and using a material having a low refractive index for the interlayer insulating film, the second transparent film of the optical waveguide and the interlayer insulation are used. It is possible to increase the amount of light totally reflected at the interface by concentrating the difference in the refractive indexes of the films and efficiently condense on the photoelectric conversion element.

  Moreover, it is preferable that the said condensing lens consists of the same material as the 2nd transparent film of the said optical waveguide, and is integral with the said 2nd transparent film. In this case, the number of manufacturing steps can be reduced, yield can be improved, and there is no interface between the condensing lens and the second transparent film of the optical waveguide. Therefore, the light incident on the condenser lens can be efficiently propagated to the second transparent film of the optical waveguide.

  Moreover, it is preferable that the said condensing lens is an upward convex lens shape, and it is more preferable that both upper and lower surfaces are convex shapes. In the case of an upward convex lens shape, the incident light can be bent efficiently in the direction of the optical waveguide. In the case where the upper and lower surfaces are convex, the incident light is bent more efficiently than in the upward convex case. I can do things.

  The etching stopper film is preferably made of aluminum oxide, aluminum nitride, or silicon nitride.

  In addition, since the thickness of the etching stopper film is a multiple of 1/4 of the incident light wavelength, the amount of reflection at the entrance of the etching stopper film can be reduced, leading to a photoelectric conversion element. It is possible to increase the output of the incident light entrance and increase the sensitivity. If the film thickness of the etching stopper film is in the vicinity of the above value, there is an effect of increasing the sensitivity. In addition, since the blue light with the shortest incident light wavelength is about 450 nm, the film thickness of the etching stopper is 112 nm or more. Therefore, damage to the photoelectric conversion element is caused during dry etching before forming the optical waveguide. As a result, it is possible to prevent the occurrence of white scratches, which are noises when an image is displayed.

  The insulating film on the semiconductor substrate and the first transparent film of the optical waveguide may be in direct contact with each other by opening a part of the etching stopper film. In this case, hydrogen is effectively supplied from the first transparent film containing hydrogen and the second transparent film through the insulating film having a high hydrogen permeability to the silicon substrate on which the photoelectric conversion element is formed. Therefore, by eliminating crystal defects in the silicon substrate on which the photoelectric conversion element is formed, it is possible to prevent white scratches, which are noises when displaying an image.

  The method for manufacturing a solid-state imaging device according to the present invention includes: a step (a) of forming an insulating film on a semiconductor substrate provided with a plurality of photoelectric conversion elements; and a step of forming the plurality of photoelectric conversion elements on the insulating film. A step (b) of forming a transfer electrode in a region located on each side, a step (c) of forming an etching stopper film on a portion of the insulating film located on the photoelectric conversion elements, A step (d) of forming an interlayer insulating film provided with a hole above each photoelectric conversion element above the transfer electrode and on the etching stopper film; and at least an inner surface of the hole of the interlayer insulating film A step (e) of forming a first transparent film having a refractive index higher than that of the interlayer insulating film, filling a hole in the interlayer insulating film on the first transparent film, and forming the interlayer insulating film And a refractive index higher than that of the first transparent film. Forming the transparent film (f), and etching back the second transparent film using a resist, and in the hole of the interlayer insulating film of the first transparent film and the second transparent film (G) forming an optical waveguide constituted by the formed portion and a condensing lens constituted by a portion of the second transparent film located on the optical waveguide and above the interlayer insulating film And.

  In the solid-state imaging device manufactured by this method, the light incident with the incident light perpendicular to the substrate surface is refracted by the condenser lens, enters the optical waveguide, and is condensed on the photoelectric conversion element. Light that is incident at an angle with respect to the light (obliquely incident light) is also refracted by the condensing lens, enters the optical waveguide, is totally reflected by its side surface and is confined in the optical waveguide, and is efficiently contained in the photoelectric conversion element. Focused. As described above, since it is possible to condense even oblique incident light having a large incident angle, which cannot be collected with the configuration without the conventional optical waveguide, the condensing efficiency is improved and the oblique incident light is Therefore, it is difficult to enter the transfer electrode and the like, reducing the smear component, and preventing incident light from propagating to the adjacent pixel, thereby preventing color mixing (crosstalk). Further, when the condensing lens has a convex lens shape in the vertical direction, the diameter of the material gas forming opening of the material forming the optical waveguide is increased in the process of forming the optical waveguide. Even if the inflow is facilitated, the pixel pitch of the solid-state imaging device is reduced, and the diameter of the optical waveguide is reduced, embedded film formation can be performed without gaps. Furthermore, hydrogen can be effectively supplied to the silicon substrate by performing heat treatment in a hydrogen atmosphere after forming the first transparent film and the second transparent film of the optical waveguide containing hydrogen. By eliminating crystal defects in the silicon substrate on which the photoelectric conversion element is formed, it is possible to prevent the occurrence of white scratches, which are noises when displaying images.

  According to the solid-state imaging device and the method for manufacturing the same of the present invention, by providing an optical waveguide made of a material having a high refractive index above the photoelectric conversion element, the light that has reached the condenser lens is efficiently converted into the photoelectric conversion element. In addition, the smear component can be reduced and color mixing (crosstalk) can be prevented. Further, by providing the optical waveguide, more incident light can be condensed on the photoelectric conversion element, and thus the incident angle can be widened. For this reason, the whole camera module using the solid-state imaging device of the present invention can be made thinner than when a conventional solid-state imaging device is used. In addition, since the incident angle can be widened, it has been necessary to optimize the shrink rate of the condenser lens and on-chip lens for each type of camera module. The apparatus can be used for various camera modules. Furthermore, the film structure on the surface of the photoelectric conversion element has a structure in which the refractive index is alternately increased and decreased, for example, silicon substrate / silicon oxide film / silicon nitride film / silicon oxynitride film / high refractive index material, By optimizing the refractive index and film thickness of the thin film, the reflectance of the incident light on the silicon substrate surface can be kept low, and the incident light condensed by the optical waveguide can be efficiently incident on the photoelectric conversion element. Furthermore, by supplying hydrogen to the photoelectric conversion element by heat treatment in hydrogen from the first transparent film containing hydrogen and the second transparent film constituting the optical waveguide, lattice defects in the silicon substrate are reduced, White scratches, which are noise components when an image is displayed, can be reduced.

(First embodiment)
A solid-state imaging device and a method for manufacturing the same according to the first embodiment of the present invention will be described below with reference to first and second examples.

-First embodiment-
FIG. 1 is a cross-sectional view showing the structure of a solid-state imaging device according to the first embodiment of the present invention.

  In the solid-state imaging device shown in FIG. 1, a photoelectric conversion element 12 is provided on a surface portion of a semiconductor substrate such as a silicon substrate, and a gate insulating film 13 made of silicon oxide is provided on the semiconductor substrate.

  A transfer electrode 14 made of polysilicon is provided on the side of the photoelectric conversion element 12 on the gate insulating film 13, and the upper surface and upper side surfaces of the transfer electrode 14 are covered with a light shielding film 16 made of tungsten. Yes. A first interlayer insulating film 15 a made of silicon oxide having a refractive index of 1.45 is provided immediately above the transfer electrode 14. The first interlayer insulating film 15 a is interposed between the transfer electrode 14 and the light shielding film 16 to insulate the transfer electrode 14 and the light shielding film 16 from each other.

  On the other hand, an etching stopper film 17 made of silicon nitride is provided on the photoelectric conversion element 12 with the gate insulating film 13 interposed therebetween, and an optical waveguide 18 is formed on the etching stopper film 17. The optical waveguide 18 is provided with a concave portion of the first transparent film 19 made of silicon oxynitride having a refractive index of 1.6 and a second portion made of silicon nitride having a refractive index of 2.0 provided inside the concave portion. And a transparent film 20. Around the optical waveguide 18, a second interlayer insulating film 15 b made of BPSG (BoroPhosphorous Silicate Glass) having a refractive index of 1.45 is formed so as to be in contact with the first transparent film 19. In addition, the planar shape when the optical waveguide 18 is viewed from above is circular, but may have a polygonal shape or the like.

  Above the optical waveguide 18, a condenser lens 21 made of silicon nitride having a refractive index of 2.0, which is the same material as the second transparent film 20 constituting the optical waveguide 18, is integrated with the second transparent film 20. Is provided. The condensing lens 21 is a condensing lens having an upwardly convex shape and is characterized in that its diameter is larger than the diameter of the optical waveguide 18. Above the condenser lens 21, the second interlayer insulating film 15 b, and the first transparent film 19, a planarizing film 22 made of a transparent polymer resin having a refractive index of 1.50, and a refractive index of 1.55 A color filter 23 made of a transparent polymer resin is sequentially laminated, and an on-chip lens 24 made of a transparent polymer resin having a refractive index of 1.60 is provided on the color filter 23.

  In addition, the portion of the first transparent film 19 that forms the side surface portion of the optical waveguide 18 is thinner than the portion of the first transparent film 19 that forms the bottom surface portion of the optical waveguide 18.

  Next, details of the solid-state imaging device according to the first embodiment will be described using the solid-state imaging device according to the first comparative example in which a part of the configuration is replaced with the prior art as a comparison target.

  FIG. 2 is a cross-sectional view illustrating a configuration of the solid-state imaging device according to the first comparative example. The solid-state imaging device of this comparative example is set to be the same as the solid-state imaging device of this embodiment shown in FIG. 1 except that it does not include an optical waveguide.

  3A and 3B show the results of measuring the sensitivity to obliquely incident light, the smear and the F value for the solid-state imaging device according to the first example and the solid-state imaging device according to the first comparative example. It is a figure which shows the result of having measured the relationship, respectively.

  Specifically, FIG. 3A shows the result of evaluating the sensitivity by measuring the output voltage from the photodiode when white parallel light is irradiated as the incident light. Here, the incident angle of light when irradiated perpendicularly to the main surface of the element (substrate) is 0 °, the incident angle is gradually increased, and incident light from 0 ° to 30 ° is irradiated. The sensitivity was measured and the sensitivity to obliquely incident light was evaluated. As a result, as shown in FIG. 3A, when the output at an incident angle of 0 ° is 100%, the incident angle at which the output is 80% has no optical waveguide. It was found that the solid-state image pickup device having the optical waveguide has an angle of 26 ° compared to 17 ° in the solid-state image pickup device of FIG. Thus, in the solid-state imaging device according to the present example, it was confirmed that the incident characteristics of light from an oblique direction are greatly improved by providing the optical waveguide.

  Subsequently, smear components of the solid-state imaging device were measured when irradiation was performed while changing the F value of the white light incident from a random direction under conditions close to the usage conditions in the actual camera module. As a result, as shown in FIG. 3B, for example, when the F value of the incident light is 4.0, the solid-state imaging device of the first comparative example having no optical waveguide is -84.7 dB. On the other hand, the solid-state imaging device of the first embodiment having an optical waveguide is −90.5 dB. When the F value of incident light is 2.0, the solid-state imaging device of the first comparative example is -80.4 dB, whereas the solid-state imaging device of the first embodiment is -88.6 dB. It can be seen that the solid-state imaging device of the first embodiment having an optical waveguide over the entire F value evaluated has a larger absolute value of dB, which is an indicator of smear characteristics, and better smear characteristics. It was. That is, in the solid-state imaging device of this example, the effect that the smear characteristic is improved by providing the optical waveguide was recognized.

  Next, in the solid-state imaging device according to the first embodiment, the film configuration on the photoelectric conversion element 12 includes a gate insulating film 13, an etching stopper film 17 made of silicon nitride, and an oxide having a refractive index of 1.6 in order from the bottom. A first transparent film 19 made of silicon nitride and a second transparent film 20 made of silicon nitride having a refractive index of 2.0 are formed. The respective film thicknesses are 20 nm for the gate insulating film 13, 130 nm for the etching stopper film 17, and 30 nm for the first transparent film 19 in order to minimize the reflectance on the photoelectric conversion element. The reflectance of light is 5%.

  That is, since the film thickness of the etching stopper film 17 is 130 nm (in the case of a green element) that is ¼ (multiple of the incident light wavelength), the reflectance when viewed alone is suppressed. Further, the film on the photoelectric conversion element 12 has a structure of gate insulating film / silicon nitride film / silicon oxynitride film / silicon nitride, and the respective film thicknesses are optimized, so that the antireflection laminated film 25 as a whole is obtained. The reflectance can be kept low.

  Therefore, in order to verify the effect of the antireflection multilayer film 25, the inventors of the present application eliminated the first transparent film 19 from the solid-state imaging device of the first embodiment, and directly nitrided the etching stopper film 17. A solid-state imaging device according to the second comparative example in which the optical waveguide 18 constituted only by the second transparent film 20 made of silicon was formed.

  FIG. 4 is a cross-sectional view illustrating a configuration of a solid-state imaging device according to a second comparative example. When the reflectance of the light incident on the optical waveguide in the solid-state imaging device having such a configuration was measured, the film on the photoelectric conversion element 12 had a gate insulating film / silicon nitride film / silicon nitride structure, Regardless of how the thickness of the insulating film is changed, the reflectivity is 20% or more, and the output of light incident on the photoelectric conversion element is reduced due to the increase in reflectivity. Therefore, it has been found that the sensitivity of the solid-state imaging device according to the second comparative example is significantly lower than that of the solid-state imaging device according to the first example.

  FIG. 9A shows the result of evaluating the sensitivity of each solid-state imaging device of the first example, the first comparative example, and the second comparative example, including this result. The figure shows the converted value of each measured value when the output voltage indicating the sensitivity (condensing efficiency) when the incident angle is 0 ° in the configuration of the first embodiment is 100.

  From this result, the sensitivity when the incident angle is 0 ° in the solid-state imaging device of the first comparative example (without the waveguide) is about 5 compared with the sensitivity of the solid-state imaging device of the first embodiment. It can be seen that the solid-state imaging device of the second comparative example (having an optical waveguide structure having a large surface reflection) decreases by about 18%. However, the sensitivity when the incident angle is 15 ° is about 65% when the incident angle is 0 ° in the first and second comparative examples having the optical waveguide structure. Thus, in the first comparative example, it is reduced to about 40%, and it has been clarified that in the configuration without the optical waveguide, the sensitivity becomes lower as the incident angle increases. From the above results, it was confirmed that the light collection efficiency can be improved by providing the optical waveguide and the antireflection laminated film. In particular, it has been found that the optical waveguide structure is effective in improving the oblique incidence characteristics of the solid-state imaging device.

  In the CCD (Charged Coupled Device) type solid-state imaging device according to the first embodiment, as shown in FIG. 1, the case where the diameter of the condenser lens is larger than the diameter of the optical waveguide has been described. In order to confirm the effect, the inventors of the present application manufactured a solid-state imaging device in which the diameter of the condensing lens is substantially the same as the diameter of the optical waveguide. The optical characteristics of the solid-state imaging device and the solid-state imaging device of this example were measured and compared.

  FIG. 5 is a cross-sectional view illustrating a configuration of a solid-state imaging device according to a third comparative example. In the solid-state imaging device shown in the figure, a photoelectric conversion element 12 is provided on a surface portion of a silicon substrate, and a gate insulating film 13 made of silicon oxide is provided on the silicon substrate.

  A transfer electrode 14 made of polysilicon is provided on the gate insulating film 13, and a light shielding film 16 made of tungsten is provided above the transfer electrode 14. A first interlayer insulating film 15 a made of silicon oxide having a refractive index of 1.45 is provided immediately above the transfer electrode 14. The first interlayer insulating film 15 a is interposed between the transfer electrode 14 and the light shielding film 16 to insulate the transfer electrode 14 and the light shielding film 16 from each other.

  On the other hand, an etching stopper film 17 made of silicon nitride is provided on the photoelectric conversion element 12 with a gate insulating film 13 interposed therebetween, and an optical waveguide 18 is formed thereon. The optical waveguide 18 includes a concave portion of the first transparent film 19 made of silicon oxynitride having a refractive index of 1.6, and a second portion made of silicon nitride having a refractive index of 2.0 provided on the concave portion. And a transparent film 20. A second interlayer insulating film 15 b made of BPSG having a refractive index of 1.45 is formed around the optical waveguide 18 so as to be in contact with the first transparent film 19.

  Above the optical waveguide 18, a condenser lens 21 made of silicon nitride having a refractive index of 2.0, which is the same material as the second transparent film 20 constituting the optical waveguide 18, is integrated with the second transparent film 20. Is provided. The condensing lens 21 is a condensing lens having an upwardly convex shape, and its diameter is the same as the diameter of the optical waveguide. Above the condenser lens 21, the second interlayer insulating film 15 b, and the first transparent film 19, a planarizing film 22 made of a transparent polymer resin having a refractive index of 1.50, and a refractive index of 1.55 A color filter 23 made of a transparent polymer resin is sequentially laminated, and an on-chip lens 24 made of a transparent polymer resin having a refractive index of 1.60 is provided on the color filter 23.

  In the solid-state imaging devices of the first embodiment and the third comparative example, the inventors of the present application measured the output voltage from the photodiode when irradiated with white parallel light as incident light, and evaluated the sensitivity. went. Here, the incident angle of light when irradiated perpendicularly to the main surface of the element is 0 °, the incident angle is gradually increased, and incident light from 0 ° to 30 ° is irradiated. Sensitivity was measured and the incident angle dependence of obliquely incident light was evaluated. As a result, as shown in FIG. 8, when the output at an incident angle of 0 ° is 100%, the incident angle at which the output is 80% is the condensing lens diameter> the optical waveguide diameter. It was 26 ° in the solid-state imaging device of the third example, whereas it was 20 ° in the solid-state imaging device of the third comparative example. From this result, it was confirmed that the solid-state imaging device in which the diameter of the condensing lens 21 is larger than the diameter of the optical waveguide can condense oblique incident light with a wide angle on the photodiode. Thus, it has been found that increasing the incident angle is effective when the diameter of the condenser lens is larger than the diameter of the optical waveguide.

  Further, FIG. 9B shows the result of evaluating the absolute value of the sensitivity of the solid-state imaging devices of the first embodiment and the third comparative example. The values shown in the table are values converted respectively with the output voltage of sensitivity when the incident angle is 0 ° as 100 in the configuration of the first embodiment.

  From this result, it was found that the sensitivity of the solid-state imaging device of the third comparative example when the incident angle is 0 ° is about 25% lower than that of the solid-state imaging device of the first example. Furthermore, the sensitivity when the incident angle is 15 ° is about 65% of the case where the incident angle is 0 ° in the solid-state imaging device of the first embodiment, whereas the solid state of the third comparative example. In the imaging apparatus, the incident angle was about 41% when the incident angle was 0 °. From this, it has been clarified that in the configuration in which the diameter of the condensing lens is the same as the diameter of the optical waveguide, the sensitivity becomes lower as the incident angle of light increases. From the above results, in the solid-state imaging device according to the first embodiment having the optical waveguide, the sensitivity and the incident characteristic of light from an oblique direction are further improved when the diameter of the condenser lens is larger than the diameter of the optical waveguide. It was confirmed that

  Next, a method for manufacturing the solid-state imaging device according to the first embodiment of the present invention will be described with reference to FIG.

  6A to 6F are cross-sectional views illustrating the manufacturing process of the solid-state imaging device according to the first embodiment of the present invention. Here, the process after the photoelectric conversion element 12, the charge transfer unit, the readout gate, and the channel stop (not shown) are formed in the surface layer portion of the silicon substrate will be described.

  In the manufacturing method of the solid-state imaging device of this embodiment, first, in the step shown in FIG. 6A, the gate insulating film 13 made of silicon oxide having a thickness of 20 nm is formed on the silicon substrate by thermal oxidation treatment. An etching stopper film 17 made of silicon nitride having a thickness of 40 nm is formed on the portion of the gate insulating film 13 formed on the photoelectric conversion element 12 by a CVD method or a sputtering method. Next, a transfer electrode 14 made of polysilicon, a first interlayer insulating film 15a covering the upper side of the transfer electrode 14, and a light shielding film 16 made of tungsten are sequentially formed on the gate insulating film 13 by CVD and patterning. Form. Here, the transfer electrode 14 is formed so as not to overlap the photoelectric conversion element 12 when seen in a plan view. Thereafter, on the etching stopper film 17 and the light shielding film 16, a second interlayer insulating film 15b made of a material mainly composed of silicon oxide such as BPSG (boron phosphorus silicate glass) is formed. At this time, since the transfer electrode 14 and the like exist, the second interlayer insulating film 15b is high on the transfer electrode 14 and low on the photoelectric conversion element 12, and the photoelectric conversion element 12 has a concave shape. After forming the BPSG, annealing is performed to flow and planarize the second interlayer insulating film 15b.

  Next, in the step shown in FIG. 6B, a resist (not shown) opening above the photoelectric conversion element 12 is formed on the second interlayer insulating film 15b, and anisotropic dry etching is performed. By performing, the part located above the photoelectric conversion element 12 among the 2nd interlayer insulation films 15b is removed, and the hole part 26 is formed. Thereafter, the resist (not shown) is removed.

  Next, in the step shown in FIG. 6C, the side surface of the hole 26, the upper surface of the etching stopper film 17 exposed at the bottom of the hole 26, and the second surface are formed by CVD such as high-density plasma CVD. A first transparent film 19 made of a silicon oxynitride film is formed so as to cover the upper surface of the interlayer insulating film 15b. At this time, the film thickness of the portion formed on the inner side surface of the hole 26 in the first transparent film 19 is that of the portion formed on the etching stopper film 17 and the second interlayer insulating film 15b. Make it thinner than the film thickness. Therefore, even if the thickness of the etching stopper film 17 is 1/4 (multiple of the incident light wavelength), for example, about 130 nm, the film thickness of the portion formed on the inner surface of the hole 26 is 1 / 2 or less, which is about 50 nm, even if the diameter of the hole 26 is about 500 nm, the diameter of the second transparent film 20 formed in the subsequent process is about 400 nm. Therefore, the second transparent film can be satisfactorily embedded without a gap, and the cross-sectional area of the second transparent film having a high refractive index through which incident light can be transmitted can be made as large as possible. Note that since this silicon oxynitride film uses silane as a raw material, the resulting film contains hydrogen richly.

  Next, in the step shown in FIG. 6D, a high-density plasma CVD film in which the silicon nitride film is embedded in the hole 26 so as to completely fill the hole 26 on the silicon oxynitride film. Form by the method. The portion embedded in the hole portion 26 of the silicon nitride film becomes the second transparent film 20, and the portion of the first transparent film 19 provided in the hole portion 26 and the second transparent film 20 are an optical waveguide. Configure. At this time, since there is a hole 26, unevenness occurs on the upper surface of the silicon nitride film. Therefore, a resist (not shown) is applied over the entire surface of the silicon nitride film, and dry etching is performed under the condition that the etching rates of the silicon nitride film and the resist are the same (etching the entire resist surface). The upper surface of the silicon nitride film is planarized by performing a back method) or a CMP method. Since this silicon nitride film uses silane as a raw material, hydrogen is richly contained immediately after formation. Subsequently, heat treatment is performed in a hydrogen atmosphere. Thus, hydrogen is supplied from the silicon oxynitride film that is the first transparent film 19 and the silicon nitride film that is the base material of the second transparent film 20 to the silicon substrate on which the photoelectric conversion element 12 is formed. can do. The photoelectric conversion element 12 is damaged during dry etching in the step shown in FIG. This damage causes image defects such as white spots and white lines in the output image. This is called white scratch, and this is caused by a crystal defect of the photoelectric conversion element. In the manufacturing method according to this example, by supplying hydrogen to the photoelectric conversion element 12, crystal defects (dangling bonds) generated by dry etching are terminated, and white scratches are reduced.

  Next, in the step shown in FIG. 6E, the condenser lens 21 that covers the hole 26 is formed on the first transparent film 19. First, after forming a resist on the upper surface of the substrate (the solid-state imaging device under fabrication), patterning and reflow are performed, so that a desired region of the planarized silicon nitride film is formed on the region located above the optical waveguide 18. A resist 27 having the same shape as the condenser lens is formed. At this time, the resist 27 is formed to have a diameter larger than that of the optical waveguide 18. Thereafter, dry etching is performed under the condition that the etching rates of the silicon nitride film and the resist are the same, and the shape of the resist 27 is transferred to the silicon nitride film, thereby having a diameter larger than the diameter of the optical waveguide 18; A condensing lens 21 having a convex shape is formed.

  Thereafter, in the process shown in FIG. 6F, the flattening film 22, the color filter 24, and the on-chip lens 25 are formed according to the normal manufacturing process of the imaging device, and the series of manufacturing processes is completed.

  According to the series of manufacturing methods described above, as described in the first embodiment, the second light source includes the condensing lens 21 having an upwardly convex shape and the optical waveguide 18 and constitutes the optical waveguide 18. The solid-state imaging device in which the transparent film 20 is integrally formed of the same material as that of the condenser lens 21 can be easily manufactured.

  In summary, the solid-state imaging device according to the first embodiment of the present invention has the following device configuration features.

First, the first device configuration has a first transparent film on the outer side and a second transparent film on the inner side, the refractive index of which is higher than that of the interlayer insulating film, and higher than that of the first transparent film. The optical waveguide of the second transparent film is higher from the upper side of the photoelectric conversion element to the condenser lens made of the same material as the second transparent film. Due to the characteristics of the apparatus configuration, it is possible to obtain an effect that sensitivity to obliquely incident light is improved and an incident angle is enlarged. Further, this feature of the device configuration can provide a further effect that smear characteristics are greatly improved.
Also, normally, in order to increase the sensitivity to obliquely incident light, it is necessary to shift (shrink) the position of the condensing lens and microlens provided on the periphery of the pixel array. The amount of shrink is strictly controlled. However, the characteristic of the first apparatus configuration greatly improves the sensitivity of oblique incident light and increases the incident angle, thereby reducing the need to strictly control the amount of shrinkage. For this reason, there is no need to finely change the amount of shrink according to each use application, and an increase in cost due to an increase in variety can be suppressed.

  Further, the second device configuration is characterized in that the film on the photoelectric conversion element has a gate insulating film / silicon nitride film (antireflection film) / silicon oxynitride film / silicon nitride in order from the bottom. The film thickness of the antireflection film is set to ¼ of the incident light wavelength, and the other film thicknesses are optimized. Due to the characteristics of the device configuration, an effect of suppressing the reflectance of incident light on the photoelectric conversion element can be obtained. In addition, due to the characteristics of the apparatus configuration, it is possible to obtain further effects of suppressing the occurrence of damage due to dry etching and preventing an increase in white flaws in the output image.

  In summary, the solid-state imaging device according to the present embodiment has the following characteristics of the device manufacturing method.

  First, the first device manufacturing method is characterized in that the film thickness of the portion formed on the inner side surface of the hole portion of the first transparent film constituting the optical waveguide is the same as that of the portion formed on the bottom surface of the hole portion. It is to be formed so as to be thinner than the film thickness. Due to the characteristics of the device manufacturing method, in the solid-state imaging device of the present embodiment, the cross-sectional area of the second transparent film having a large refractive index formed inside the first transparent film can be increased. For this reason, voids are less likely to be generated in the second transparent film, and a decrease in sensitivity due to voids can be prevented.

  Further, the second device manufacturing method is characterized in that there are two types of films constituting the optical waveguide, and the second transparent film and the condenser lens constituting the optical waveguide are continuously formed of the same material. It is that. For this reason, compared with the case where there are three or more types of films constituting the optical waveguide, the internal stress generated at the time of film formation can be suppressed to be small, so that cracks and peeling are less likely to occur in the optical waveguide. In addition, since the types of films constituting the optical waveguide are relatively small, the number of manufacturing steps can be reduced as compared with the solid-state imaging device according to the second conventional example. In addition, because of the above-described features, it is possible to eliminate the reflection of light between the condensing lens and the second transparent film, so that the reflectance of light between the condensing lens and the optical waveguide is reduced, and the light is collected. Light efficiency can be improved.

  Furthermore, in the manufacturing method of this example, since the hydrogen contained in the first transparent film and the second transparent film can be effectively supplied to the photoelectric conversion element during the manufacturing process, crystal defects of the photoelectric conversion element are recovered. The occurrence of white scratches in the output image can be suppressed. The etching stopper film 17 is preferably partially removed so that hydrogen can easily diffuse into the photoelectric conversion element. Furthermore, due to the characteristics of the manufacturing method of the present embodiment, by stopping dry etching with an etching stopper, the occurrence of damage to the photodiode due to dry etching is suppressed, and an increase in white scratches on the output image is prevented. Further effects can be obtained.

  Although the example in which the etching stopper film 17 is made of silicon nitride has been described above in the solid-state imaging device according to the first embodiment, the same effect can be obtained even if it is made of aluminum oxide or aluminum nitride. . Even in this case, the etching stopper film 17 is preferably formed by a method in which hydrogen remains after the film formation. Also in this case, the photoelectric conversion element 12 is refracted in the film configuration from the silicon substrate to the optical waveguide 18, that is, in the silicon substrate / gate insulating film 13 / etching stopper film 17 / first transparent film 19 / second transparent film 20. If the rate repeats increasing and decreasing, reflection of light incident on the optical waveguide 18 can be prevented. Furthermore, by optimizing the film thickness of each film, reflection of light incident on the optical waveguide 18 can be further suppressed. The same applies to the other embodiments.

  In the above description, the first transparent film 19 forming the optical waveguide 18 is made of silicon oxynitride, and the second transparent film 20 and the condenser lens are made of silicon nitride. However, in the solid-state imaging device of the present invention, The material constituting the optical waveguide is not limited to this material. The constituent material of the first transparent film 19 may be any material that has a refractive index higher than that of the second interlayer insulating film 15b and lower than that of the second transparent film 20 and that contains hydrogen after film formation. For example, even when aluminum oxide, magnesium oxide or the like is used, the same effect as that of the first embodiment can be obtained.

  The second transparent film 20 and the condenser lens 21 are made of a material that has a refractive index higher than that of the first transparent film 19 and is 2.0 or more, and is made of a material containing hydrogen after film formation. For example, even if it is composed of titanium oxide, tantalum oxide, niobium oxide, tungsten oxide, zirconium oxide, zinc oxide, indium oxide, hafnium oxide, etc., the same effect as in the first embodiment can be obtained.

  If the on-chip lens 24 is provided in addition to the condenser lens 21, the condenser lens 21 may not function as a so-called convex lens. In other words, the light collected by the condenser lens 21 by the on-chip lens 24 may be converted into parallel light by the condenser lens 21. In this case, the refractive indexes of the condenser lens 21 and the flattening film 22 are reversed from those of the present embodiment. In this case, since incident light can be made parallel to the side wall of the optical waveguide 18, attenuation of incident light due to reflection can be prevented.

  In the CCD (Charged Coupled Device) type solid-state imaging device according to the first embodiment, as shown in FIG. 1, the shape of the optical waveguide is the same from the position directly above the photoelectric conversion element to the lower surface position of the condenser lens. Although the case of the area has been described, the shape of the optical waveguide is not limited to this shape, and its cross-sectional area increases continuously or stepwise as it goes from directly above the photoelectric conversion element to the condenser lens. It may be a shape. The case where the cross-sectional area of the optical waveguide continuously increases as it is closer to the condenser lens will be described below.

-Second embodiment-
FIG. 7 is a sectional view showing the structure of a solid-state imaging device according to the second embodiment of the present invention. In the solid-state imaging device shown in the figure, a photoelectric conversion element 12 is provided on a surface portion of a silicon substrate, and a gate insulating film 13 made of silicon oxide is provided on the silicon substrate.

  A transfer electrode 14 made of polysilicon is provided on the gate insulating film 13, and an upper surface and a side surface of the transfer electrode 14 are covered with a light shielding film 16 made of tungsten with a first interlayer insulating film 15 a interposed therebetween. . The first interlayer insulating film 15a is made of silicon oxide having a refractive index of 1.45, and is interposed between the transfer electrode 14 and the light shielding film 16, thereby insulating the transfer electrode 14 and the light shielding film 16 from each other. Yes.

  On the other hand, an etching stopper film 17 made of silicon nitride is provided on the photoelectric conversion element 12 with the gate insulating film 13 interposed therebetween, and an optical waveguide 18 is formed on the etching stopper film 17. The optical waveguide 18 includes a concave portion of the first transparent film 19 made of silicon oxynitride having a refractive index of 1.6, and silicon nitride having a refractive index of 2.0 provided on the concave portion. And a second transparent film 20 made of The optical waveguide 18 has such a shape that its cross-sectional area increases as it goes from the photoelectric conversion element 12 (lower side) to the upper condenser lens. This is the difference between the solid-state imaging device of the present embodiment and the solid-state imaging device of the first embodiment.

  A second interlayer insulating film 15 b made of BPSG having a refractive index of 1.45 is formed around the optical waveguide 18 so as to be in contact with the first transparent film 19. In other words, the first transparent film 19 is formed along the upper surface of the second interlayer insulating film 15b and the inner surface of the hole.

  On the optical waveguide 18, a condenser lens 21 made of silicon nitride having a refractive index of 2.0, which is the same material as the second transparent film 20 constituting the optical waveguide 18, is integrated with the second transparent film 20. Is provided. The condensing lens 21 has an upwardly convex shape. Above the condenser lens 21, the second interlayer insulating film 15 b, and the first transparent film 19, a planarizing film 22 made of a transparent polymer resin having a refractive index of 1.50, and a refractive index of 1.55 A color filter 23 made of a transparent polymer resin is sequentially laminated, and an on-chip lens 24 made of a transparent polymer resin having a refractive index of 1.60 is provided on the color filter 23.

  As in the first embodiment, the solid-state imaging device of the second embodiment having the above configuration and the first embodiment described above is irradiated with white parallel light as incident light, and the photodiode The output voltage from was measured to evaluate the sensitivity. When incident light is irradiated perpendicularly to the main surface of the element, the incident angle is 0 °, and the sensitivity when the incident angle is continuously increased from 0 ° to 30 ° obliquely is measured. The oblique incident angle dependence of the imaging device was evaluated.

  As a result, the incident angle at which the output voltage was 80% when the output voltage when the incident angle was 0 ° was set to 100% was 26 ° in the solid-state imaging device of the first example. On the other hand, in the solid-state imaging device of the second embodiment, the angle is 27 °, and the solid-state imaging device of the second embodiment has good optical characteristics similar to those of the solid-state imaging device of the first embodiment. I understood.

  Further, the inventors of the present application evaluated the absolute value of sensitivity in the solid-state imaging devices according to the first and second examples. The result is shown in FIG. The values shown in the figure are values obtained by converting the detected output voltages with the output voltage when the incident angle is 0 ° as 100 in the solid-state imaging device of the first embodiment.

  From this result, it was found that the sensitivity when the incident angles of light are 0 ° and 15 ° is substantially the same in the solid-state imaging devices of the first embodiment and the second embodiment. In addition, according to the optical waveguide 18 according to the second embodiment, the cell size in the solid-state imaging device is reduced, and the sectional area of the opening for providing the optical waveguide 18 directly above the photoelectric conversion element is reduced. Even in this case, it is possible to improve the embedding property of the second transparent film without deteriorating the light incident characteristic. In addition, when the second interlayer insulating film 15b is thickened or the cell size is reduced, the aspect ratio of the opening is increased, and the cross-sectional area is inevitably reduced at the bottom of the opening. Even in this case, by providing the optical waveguide 18 having the second transparent film 20 integrated with the condenser lens 21 at the opening of the second interlayer insulating film 15b, excellent light incident characteristics and sensitivity can be exhibited. can do.

  In the present embodiment, only the CCD solid-state imaging device has been described. However, the optical waveguide of the present invention can also be applied to a MOS solid-state imaging device using a CMOS or the like.

(Second Embodiment)
Hereinafter, a solid-state imaging device and a manufacturing method thereof according to a second embodiment of the present invention will be described with reference to the drawings.

-Third embodiment-
FIG. 10 is a cross-sectional view illustrating a structure of a solid-state imaging device according to a third example which is an example of the second embodiment of the present invention. The solid-state imaging device of this embodiment is a CCD type solid-state imaging device.

  In the solid-state imaging device shown in FIG. 10, a photoelectric conversion element 12 is provided on the surface portion of a silicon substrate, and a gate insulating film 13 made of silicon oxide is provided on the silicon substrate.

  A transfer electrode 14 made of polysilicon is provided on the gate insulating film 13, and the upper surface and side surfaces of the transfer electrode 14 are covered with a light shielding film 16 made of tungsten with the first interlayer insulating film 15 a interposed therebetween. Yes. The first interlayer insulating film 15a is made of silicon oxide having a refractive index of 1.45, and is interposed between the transfer electrode 14 and the light shielding film 16, thereby insulating the transfer electrode 14 and the light shielding film 16 from each other. Yes.

  On the other hand, an etching stopper film 17 made of silicon nitride is provided on the photoelectric conversion element 12 with the gate insulating film 13 interposed therebetween, and an optical waveguide 18 is formed on the etching stopper film 17. The optical waveguide 18 includes a concave portion of the first transparent film 19 made of silicon oxynitride having a refractive index of 1.6, and silicon nitride having a refractive index of 2.0 provided on the concave portion. And a second transparent film 20 made of Around the optical waveguide 18, a second interlayer insulating film 15 b made of BPSG having a refractive index of 1.45 is formed so as to be in contact with the first transparent film 19.

  On the optical waveguide 18, a condenser lens 21 made of silicon nitride having a refractive index of 2.0, which is the same material as the second transparent film 20 constituting the optical waveguide 18, is integrated with the second transparent film 20. Is provided. The condensing lens 21 is characterized in that both upper and lower surfaces have a convex shape. Above the condenser lens 21 and above the second interlayer insulating film 15b, a planarizing film 22 made of a transparent polymer resin having a refractive index of 1.50 and a color made of a transparent polymer resin having a refractive index of 1.55. Filters 23 are sequentially laminated, and an on-chip lens 24 made of a transparent polymer resin having a refractive index of 1.60 is provided on the color filter 23.

  In order to describe the details of the solid-state imaging device according to the present embodiment, a solid-state imaging device according to a fourth comparative example, in which a part of the configuration was changed, was manufactured, and performance comparison was performed with the solid-state imaging device according to the present embodiment.

  FIG. 11 is a cross-sectional view illustrating a configuration of a solid-state imaging device according to a fourth comparative example. The solid-state imaging device shown in the figure has the same configuration as the solid-state imaging device of the third embodiment, except that no optical waveguide is provided.

  In the solid-state imaging devices of the third embodiment and the fourth comparative example, the inventors of the present application measured the output voltage from the photodiode when irradiated with white parallel light as incident light, and evaluated the sensitivity. went. Here, the incident angle of light when irradiated perpendicularly to the main surface of the element is 0 °, the incident angle is gradually increased, and incident light from 0 ° to 30 ° is irradiated. The sensitivity was measured, and the oblique incident angle dependency was evaluated.

  FIG. 12A is a diagram illustrating the results of measuring the relative sensitivity of obliquely incident light with the solid-state imaging devices of the third example and the fourth comparative example. From this result, when the output at an incident angle of 0 ° is 100%, the incident angle at which the output is 80% is 18 ° in the solid-state imaging device of the fourth comparative example having no optical waveguide. In contrast, the solid-state imaging device of the third example having an optical waveguide has an angle of 29 °, and the solid-state imaging device of the present example can collect obliquely incident light with a wider angle on the photodiode. As described above, it was confirmed that the light incident from the oblique direction can be effectively collected in the photoelectric conversion element by providing the optical waveguide.

  Subsequently, smear components of the solid-state imaging device were measured when irradiation was performed while changing the F value of the white light incident from a random direction under conditions close to the usage conditions in the actual camera module. As a result, as shown in FIG. 12B, for example, when the F value of the incident light is 4.0, the solid-state imaging device of the fourth comparative example having no optical waveguide is −85.2 dB. On the other hand, the solid-state imaging device of the third embodiment having an optical waveguide is −92.3 dB. When the F value of incident light is 2.0, the solid-state imaging device of the fourth comparative example is -81.3 dB, whereas the solid-state imaging device of the third embodiment is -90.2 dB. It was found that the solid-state imaging device of the third example showed better smear characteristics over the entire range of the evaluated F value. That is, in the solid-state imaging device of this example, the effect that smear characteristics are improved by providing the optical waveguide was recognized.

  Next, in the solid-state imaging device according to the third embodiment, the film configuration on the photoelectric conversion element 12 includes a gate insulating film 13, an etching stopper film 17 made of silicon nitride, and a refractive index of 1.6 in order from the bottom. A first transparent film 19 made of silicon oxynitride and a second transparent film 20 made of silicon nitride having a refractive index of 2.0. The respective film thicknesses are 20 nm for the gate insulating film 13, 130 nm for the etching stopper film 17, and 30 nm for the first transparent film 19 in order to minimize the reflectance on the photoelectric conversion element 12. The light reflectance at the time is 5%.

  That is, since the etching stopper film 17 is 130 nm (in the case of a green element) that is ¼ of the incident light wavelength, the reflectance when viewed alone is suppressed. Further, the film on the photoelectric conversion element 12 has a structure of gate insulating film / silicon nitride film / silicon oxynitride film / silicon nitride, and the respective film thicknesses are optimized, so that the antireflection laminated film 25 as a whole is obtained. The reflectance can be kept low.

  Next, in order to verify the effect of the antireflection laminated film 25, the inventors of the present application eliminate the first transparent film made of silicon oxynitride and remove the etching stopper film 17 made of silicon nitride as shown in FIG. A solid-state imaging device according to the fifth comparative example in which the second transparent film 20 made of silicon nitride was directly formed thereon was fabricated.

  FIG. 13 is a cross-sectional view illustrating a configuration of a solid-state imaging device according to a fifth comparative example. As a result of measuring the reflectance of the light in the solid-state imaging device shown in the figure, the film on the photoelectric conversion element 12 has a structure of gate insulating film / silicon nitride film / silicon nitride. Regardless of how it is changed, the reflectivity is 20% or more, and the increase in reflectivity reduces the output of light incident on the photoelectric conversion element, greatly reducing the sensitivity.

  FIG. 9C shows the result of evaluating the sensitivity of the solid-state imaging device according to the third example, the fourth comparative example, and the fifth comparative example described above. The figure shows the converted value of each measured value when the output voltage indicating the sensitivity (condensing efficiency) when the incident angle is 0 ° in the configuration of the first embodiment is 100.

  From this result, the sensitivity when the incident angle is 0 ° in the solid-state imaging device of the fourth comparative example is reduced by about 2% compared to the solid-state imaging device of the third embodiment, and the sensitivity of the fifth comparative example is The sensitivity of the solid-state imaging device under the same conditions was reduced by about 15% compared to the third example. However, the sensitivity when the incident angle is 15 ° is reduced to about 67% of the output when the incident angle is 0 ° in the third and fifth comparative examples of the optical waveguide structure. On the other hand, in the 4th comparative example, it fell to about 42%, and it became clear that sensitivity becomes lower as the incident angle increases in the configuration without the optical waveguide. From the above results, the effect of the optical waveguide and the effect of the antireflection laminated film became clear.

  Next, a method for manufacturing a solid-state imaging device according to the second embodiment (third example) of the present invention will be described with reference to FIG.

14A to 14F are cross-sectional views illustrating the manufacturing process of the solid-state imaging device according to the third embodiment of the present invention. Here, the process after the photoelectric conversion element 12, the charge transfer unit, the readout gate, and the channel stop (not shown) are formed in the surface layer portion of the silicon substrate will be described.

In the method of manufacturing the solid-state imaging device of this embodiment, first, in the step shown in FIG. 14A, the gate insulating film 13 made of silicon oxide having a thickness of 20 nm is formed on the silicon substrate by thermal oxidation. An etching stopper film 17 made of silicon nitride having a thickness of 40 nm is formed on the portion of the gate insulating film 13 formed on the photoelectric conversion element 12 by a CVD method or a sputtering method. Next, a transfer electrode 14 made of polysilicon, a first interlayer insulating film 15a covering the upper side of the transfer electrode 14, and a light shielding film 16 made of tungsten are sequentially formed on the gate insulating film 13 by CVD and patterning. Form. Thereafter, on the etching stopper film 17 and the light shielding film 16, a second interlayer insulating film 15b made of a material mainly composed of silicon oxide such as BPSG (boron phosphorus silicate glass) is formed.

  At this time, since the transfer electrode 14 and the like exist, the second interlayer insulating film 15b is high on the transfer electrode 14 and low on the photoelectric conversion element 12, and the photoelectric conversion element 12 has a concave shape. This shape can be used as the shape of a downwardly convex lens. Alternatively, after planarization by a flow, the resist is patterned, and a portion of the second interlayer insulating film 15b located above the photoelectric conversion element 12 is isotropically etched by a wet etching process, thereby FIG. A shape as shown in a) can also be formed.

  Next, in the step shown in FIG. 14B, a resist (not shown) that opens above the photoelectric conversion element 12 is formed on the second interlayer insulating film 15b, and anisotropic dry etching is performed. By performing, the part located above the photoelectric conversion element 12 among the 2nd interlayer insulation films 15b is removed, and the hole part 26 is formed. Thereafter, the resist (not shown) is removed.

  Next, in the step shown in FIG. 14C, silicon oxynitride is formed on the second interlayer insulating film 15b including the inner surface of the hole 26 and the etching stopper film 17 exposed at the bottom of the hole 26 by CVD. A first transparent film 19 made of a film is formed. At this time, the film thickness of the first transparent film 19 formed on the inner surface of the hole 26 is the same as that of the first transparent film 19 formed on the etching stopper film 17 and on the second interlayer insulating film 15b in a region other than the hole 26. The first transparent film 19 is formed to be thinner than the film thickness. Accordingly, even if the film thickness of the etching stopper film 17 is 1/4 (multiple of the incident light wavelength), for example, about 130 nm, the film thickness formed on the inner surface of the hole 26 is ½ or less. Therefore, even if the diameter of the hole 26 is about 500 nm, the diameter of the second transparent film 20 formed in the subsequent process is secured to about 400 nm. For this reason, the second transparent film 20 can be satisfactorily embedded without a gap, and the cross-sectional area of the high-refractive-index second transparent film 20 through which incident light is transmitted can be made as large as possible. Note that since this silicon oxynitride film uses silane as a raw material, the resulting film contains hydrogen richly.

  Next, in the step shown in FIG. 14D, the second transparent film 20 made of a silicon nitride film is formed on the first transparent film 19 so as to completely fill the hole 26. It is formed by a high density plasma CVD method with good embeddability. At this time, since there is the hole 26, unevenness occurs on the upper surface of the silicon nitride film. Therefore, a resist (not shown) is applied over the entire silicon nitride film so that the upper surface is flat, and dry etching is performed under the condition that the etching rates of the silicon nitride film and the resist are the same (resist entire surface etch back). Or the CMP method is performed to planarize the upper surface of the silicon nitride film. Note that since this silicon nitride film uses silane as a raw material, the resulting film contains rich hydrogen.

  In the solid-state imaging device according to the present embodiment, the upper portion of the hole 26 has a lens shape that protrudes downward, so that it has a large opening. For this reason, since the inflow of the source gas becomes easier than the solid-state imaging device of the first embodiment, the embeddability is further improved. Therefore, even when the cell size of the solid-state imaging device is further reduced and the diameter of the hole is reduced, the second transparent film can be embedded without generating a void in the hole.

  Next, after planarizing the upper surface of the silicon nitride film, heat treatment is performed in a hydrogen atmosphere. Thus, hydrogen can be supplied from the silicon oxynitride film as the first transparent film 19 and the silicon nitride film as the second transparent film 20 to the silicon substrate on which the photoelectric conversion element 12 is provided. The photoelectric conversion element 12 is damaged at the time of dry etching in the step shown in FIG. 14B, and this appears as an image defect of an output image such as a white spot or a white line. This is called white scratch, and this is caused by a crystal defect of the photoelectric conversion element 12. By supplying hydrogen to the photoelectric conversion element 12, crystal defects (dangling bonds) generated by dry etching are terminated, and white scratches are reduced.

  Next, the condenser lens 21 is formed in the step shown in FIG. In this step, first, a resist 27 having the same shape as the upper side of a desired condensing lens is formed on a portion of the planarized silicon nitride film located above the optical waveguide by patterning and reflow. At this time, the diameter of the lens is formed to be larger than the diameter of the optical waveguide.

  Thereafter, dry etching is performed under the condition that the etching rates of the silicon nitride film and the resist are the same, and the shape of the resist 27 is transferred to the silicon nitride film, whereby the condensing lens 21 whose upper and lower surfaces are both convex is formed. Form.

  Thereafter, in the process shown in FIG. 14F, the planarization film 22, the color filter 23, and the on-chip lens 24 are sequentially formed in accordance with the normal manufacturing process of the image sensor, and the series of manufacturing processes is completed.

  According to the series of manufacturing methods described above, a solid-state imaging device composed of the same material that is continuous from the condensing lens 21 whose upper and lower surfaces are convex to the second transparent film 20 that forms the optical waveguide, It can be easily manufactured.

  In the above description, the etching stopper film 17 is set to ¼ (a multiple of) the incident light wavelength. For example, 130 nm for a green element, 110 nm for a blue element, and 160 nm for a red element. Thus, the reflectance of light at each wavelength can be lowered by changing the thickness of the etching stopper film for each wavelength of incident light. Specifically, after an etching stopper film having a thickness of 160 nm is formed, the portions provided on the green and blue pixels are patterned and etched so that the etching stopper film has a desired thickness. . In addition, since the thinnest film thickness of the etching stopper film is relatively as large as 110 nm, damage to the photoelectric conversion element when performing dry etching for forming the hole of the optical waveguide can be reduced.

  For comparison, as a result of evaluating white scratches when the film thickness of the etching stopper was formed at a thickness of 1/2 each of the above values, the number of white scratches increased by 10 times or more. . Therefore, by setting the thickness of the etching stopper film to 1/4 (multiple of the incident light wavelength), it is possible to reduce the number of white scratches as well as to reduce the reflectance of the incident light. Can have both.

  In summary, the solid-state imaging device according to the third embodiment of the present invention has the following features.

  First, the first device configuration is characterized by having a first transparent film 19 on the outside and a second transparent film 20 on the inside, the refractive index of which is higher than that of the second interlayer insulating film 15b, and An optical waveguide in which the second transparent film 20 is higher than the first transparent film 19 is provided between the photoelectric conversion element 12 and the condenser lens 21, and the condenser lens 21 is connected to the second transparent film 20. It is composed of the same material. With this configuration, the sensitivity to obliquely incident light is improved and the effect of increasing the incident angle of light is obtained. In addition, the smear characteristics are greatly improved due to the characteristics of the device configuration.

  Usually, in order to increase the sensitivity of obliquely incident light, it is necessary to shrink the condensing lens and the microlens in the periphery of the pixel, and the amount of shrinkage is strictly controlled according to each application. However, the characteristic of the first apparatus configuration greatly improves the sensitivity of oblique incident light and increases the incident angle, thereby reducing the need to strictly control the amount of shrinkage. For this reason, it is not necessary to finely change the amount of shrink according to each use application, and an increase in cost due to an increase in the types of solid-state imaging devices can be suppressed.

  Further, the second device configuration is characterized in that the film on the photoelectric conversion element 12 has the following structure: gate insulating film / silicon nitride film (antireflection film) / silicon oxynitride film / silicon nitride. The film thickness is set to 1/4 of the incident light wavelength, and other film thicknesses are optimized. Due to the characteristics of the apparatus configuration, the reflectance of incident light to the photoelectric conversion element 12 can be kept low. In addition, this feature of the apparatus configuration can reduce the occurrence of white scratches caused by damage caused by dry etching.

  Further, a third device configuration feature of the solid-state imaging device of the present embodiment is that the upper and lower surfaces of the condenser lens 21 have a convex shape. With this configuration, it is possible to collect light at a wider angle than when using a convex lens having a convex shape as described in the first embodiment. Smear characteristics are also improved.

  In the solid-state imaging device according to the present embodiment, as in the solid-state imaging device according to the first embodiment, a partial film formed on the inner surface of the hole 26 in the first transparent film 19 forming the optical waveguide. The thickness is formed so as to be thinner than the thickness of the portion formed on the bottom surface of the hole 26. For this reason, the cross-sectional area of the 2nd transparent film | membrane 20 with a large refractive index formed inside the 1st transparent film | membrane 19 can be taken large. Further, hydrogen contained in the first transparent film 19 and the second transparent film 20 can be effectively supplied to the photoelectric conversion element 12 at the time of manufacturing, thereby reducing white scratches caused by crystal defects of the photoelectric conversion element 12. be able to.

  Furthermore, since the two films constituting the optical waveguide are two types, and the second transparent film 20 and the condenser lens 21 constituting the optical waveguide are integrally formed of the same material, the number of manufacturing steps is increased. Can be reduced. Further, since there is no light reflection between the condensing lens 21 and the second transparent film 20, it is possible to obtain a further effect that the reflectance is reduced and the light condensing rate is improved.

  The solid-state imaging device of the present invention is useful as an imaging device used for a digital video camera, a digital still camera, a mobile phone with a photographic function, or the like. It can also be applied to elements used in image acquisition devices such as digital scanners and medical / industrial image sensors.

It is sectional drawing which shows the structure of the solid-state imaging device concerning 1st Example of this invention. It is sectional drawing which shows the structure of the solid-state imaging device which concerns on a 1st comparative example. (A), (b) is the result of having measured the sensitivity with respect to diagonally incident light about the solid-state imaging device concerning a 1st Example, and the solid-state imaging device concerning a 1st comparative example, and the relationship between smear and F value. It is a figure which shows the result of having measured each. It is sectional drawing which shows the structure of the solid-state imaging device which concerns on a 2nd comparative example. It is sectional drawing which shows the structure of the solid-state imaging device which concerns on a 3rd comparative example. (A)-(f) is sectional drawing which shows the manufacturing process of the solid-state imaging device which concerns on the 1st Example of this invention. It is sectional drawing which shows the structure of the solid-state imaging device which concerns on the 2nd Example of this invention. It is a figure which shows the measurement result of the sensitivity with respect to diagonally incident light in the solid-state imaging device which concerns on a 1st Example and a 3rd comparative example. (A)-(c) is a figure which shows the result of having measured the condensing efficiency in the solid-state imaging device concerning the 1st-3rd Example and the 1st-5th comparative example. It is sectional drawing which shows the structure of the solid-state imaging device which concerns on the 3rd Example of this invention. It is sectional drawing which shows the structure of the solid-state imaging device which concerns on a 4th comparative example. (A) is a figure which shows the result of having measured the relative sensitivity of the obliquely incident light with the solid-state imaging device of the 3rd Example and the 4th comparative example, respectively, (b) is the case where there is a waveguide It is a figure which shows the relationship between the smear and F value in a case. It is sectional drawing which shows the structure of the solid-state imaging device which concerns on the 5th comparative example of this invention. (A)-(f) is sectional drawing which shows the manufacturing process of the solid-state imaging device which concerns on the 2nd Embodiment of this invention. It is sectional drawing which shows the structure of the solid-state imaging device which concerns on a 5th comparative example. It is sectional drawing which shows the solid-state imaging device which concerns on a 2nd prior art example. It is sectional drawing which shows the structure of the solid-state imaging device which concerns on a 3rd prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 12 Photoelectric conversion element 13 Gate insulating film 14 Transfer electrode 15a 1st interlayer insulating film 15b 2nd interlayer insulating film 16 Light shielding film 17 Etching stopper film 18 Optical waveguide 19 1st transparent film 20 2nd transparent film 21 Condensing Lens 22 Planarizing film 23 Color filter 24 On-chip lens 25 Antireflection laminated film 26 Hole 27 Resist

Claims (21)

A plurality of photoelectric conversion elements provided in a semiconductor substrate;
An insulating film provided on the semiconductor substrate;
An etching stopper film provided on the insulating film;
A transfer electrode provided on the insulating film and on a side of the photoelectric conversion element;
An interlayer insulating film provided on the etching stopper film and above the transfer electrode, and having a hole formed above each of the plurality of photoelectric conversion elements;
A first transparent film provided above each photoelectric conversion element along the inner wall of the hole, and a second transparent film provided on the first transparent film and filling the hole An optical waveguide having
A condenser lens formed of the same material as the second transparent film, and disposed over the optical waveguide from above the interlayer insulating film,
The first transparent film, the second transparent film, and the condensing lens all have a refractive index higher than that of the interlayer insulating film, and the refractive index of the first transparent film is the second transparent film. And a solid-state imaging device having a refractive index lower than that of the condenser lens.   The solid-state imaging device according to claim 1, wherein a diameter of the condensing lens is larger than a diameter of the optical waveguide.   3. The solid-state imaging device according to claim 1, wherein the optical waveguide has a shape in which a cross-sectional area increases from a lower side to an upper side. 4.   The film thickness of the part provided on the side wall of the said hole part among said 1st transparent films is thinner than the film thickness of the part provided in the bottom face of the said hole part. The solid-state imaging device according to any one of 3.   5. The solid-state imaging device according to claim 1, wherein an upper surface of the condenser lens is convex.   The solid-state imaging device according to claim 5, wherein at least a part of the lower surface of the condenser lens is convex.   The said insulating film, the said etching stopper film | membrane, the said 1st transparent film, and the said 2nd transparent film comprise the antireflection laminated film with respect to the light which injects into each said photoelectric conversion element, The 1st aspect characterized by the above-mentioned. 6. The solid-state imaging device according to claim 1. Above the plurality of photoelectric conversion elements and the condenser lens, color filters having different colors are provided,
8. The solid-state imaging device according to claim 1, wherein a thickness of the etching stopper film is a multiple of ¼ of a wavelength of light incident on each of the photoelectric conversion elements. .   9. The solid according to claim 1, wherein the first transparent film of the optical waveguide is made of one selected from aluminum oxide, magnesium oxide, and silicon oxynitride. Imaging device.   The second transparent film and the condenser lens are made of one selected from titanium oxide, tantalum oxide, niobium oxide, tungsten oxide, zirconium oxide, zinc oxide, indium oxide, hafnium oxide, and silicon nitride. The solid-state imaging device according to any one of claims 1 to 9.   The solid-state imaging device according to claim 1, wherein the etching stopper film is made of one selected from aluminum oxide, aluminum nitride, and silicon nitride.   The solid-state imaging device according to claim 1, wherein the interlayer insulating film is made of a material mainly composed of silicon oxide.   The solid-state imaging device according to claim 1, wherein the first transparent film and the second transparent film contain hydrogen. Further comprising a light-shielding film that covers an upper surface and a side surface of the transfer electrode, and an opening is formed above each photoelectric conversion element;
The area of the upper surface of the etching stopper film is larger than the cross-sectional area of the optical waveguide and smaller than the opening of the light shielding film,
The solid-state imaging device according to claim 1, wherein a part of the first transparent film is in contact with the insulating film. A step (a) of forming an insulating film on a semiconductor substrate provided with a plurality of photoelectric conversion elements;
A step (b) of forming a transfer electrode in a region located on a side of each of the plurality of photoelectric conversion elements on the insulating film;
A step (c) of forming an etching stopper film on a portion of the insulating film located on the photoelectric conversion elements;
A step (d) of forming an interlayer insulating film provided with a hole above each photoelectric conversion element above the transfer electrode and above the etching stopper film;
A step (e) of forming a first transparent film that covers at least the inner surface of the hole of the interlayer insulating film and has a higher refractive index than the interlayer insulating film;
A step (f) of filling a hole portion of the interlayer insulating film on the first transparent film and forming a second transparent film having a higher refractive index than the interlayer insulating film and the first transparent film;
Etching back the second transparent film using a resist, and an optical waveguide constituted by a portion of the first transparent film and the second transparent film formed in a hole of the interlayer insulating film; And (g) forming a condensing lens composed of a portion of the second transparent film located on the optical waveguide and above the interlayer insulating film. Hydrogen remains in the first transparent film and the second transparent film formed in the step (e) and the step (f),
The method of manufacturing a solid-state imaging device according to claim 15, further comprising a step (h) of performing a heat treatment in a hydrogen atmosphere after the step (e) and the step (f).   The film thickness of the portion of the first transparent film formed in the step (e) formed on the sidewall of the hole portion of the interlayer insulating film is formed on the etching stopper film on the bottom surface of the hole portion. The method of manufacturing a solid-state imaging device according to claim 15 or 16, wherein the thickness is smaller than the thickness of the portion.   18. The solid according to claim 15, wherein the hole of the interlayer insulating film and the optical waveguide have a shape in which a cross-sectional area increases from the bottom to the top. Manufacturing method of imaging apparatus. The step (d) includes a step (d1) of forming the interlayer insulating film in which a concave portion having a convex shape is formed on the upper portion, and a part of the portion of the interlayer insulating film in which the concave portion is formed. And (d2) forming a hole that reaches the etching stopper by removing the hole.
19. The method of manufacturing a solid-state imaging device according to claim 15, wherein a lower surface of the condensing lens has a downwardly convex shape along the concave portion.   20. The method according to claim 15, wherein, in the step (e) and the step (f), the first transparent film and the second transparent film are formed using a high-density plasma CVD method. A method for manufacturing the solid-state imaging device according to claim 1.   21. The step (g) includes performing heat treatment after patterning the resist, and forming the condensing lens by transferring an upward convex resist shape by an etch back method. Any one of them is a method for manufacturing a solid-state imaging device.

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