JP2001044401A - Solid-state image pickup element and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve sensitivity by improving the rate that incident light reaches a photoelectric conversion part, and particularly, to decrease the number of smears in a CCD slid-state image pickup element. SOLUTION: A tapered reflection film 5 having a light reflecting characteristic is formed on a light receiving part of a photoelectric conversion part 2. Transparent films 18, 19 and 20, whose refractive indexes are higher in the center than in the vicinity of the light receiving part, are formed on the light receiving part of the photoelectric conversion part 2 which is surrounded by the reflection film 5. An light b which was incident to a solid-state image pickup device can be effectively guided in the direction to the light receiving part of the photoelectric conversion part 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state imaging device and a method for manufacturing the same, and more particularly, to a solid-state imaging device with improved sensitivity and a method for manufacturing the same.

[0002]

2. Description of the Related Art A plan view of a conventional solid-state imaging device is shown in FIG.
FIG. 18A is a cross-sectional view taken along a line AA ′ in FIG. 18A. As shown in FIG. 18A, the conventional solid-state imaging device has an on-chip lens 27 for collecting incident light on a photoelectric conversion unit 23. Also,
As shown in FIG. 18B, the photoelectric conversion unit 23 is formed in the surface region of the substrate 22, and the substrate 22 and the photoelectric conversion unit 2 are formed.
3 is covered with an insulating film 24. Then, a light-shielding film 25 having an opening on the light-receiving part of the photoelectric conversion part 23 is formed on the insulating film 24, and a transparent flat film 26 is formed on the entire surface of the insulating film 24 on the light-receiving part of the photoelectric conversion part and the light-shielding film 25. Then, an on-chip lens 27 is further formed thereon. Although an actual solid-state imaging device has electrodes, wirings, and the like on the substrate 22, it is not directly related to the solid-state imaging device of the present invention, and a description thereof is omitted here.

Generally, the sensitivity of a solid-state imaging device is defined by the magnitude of the output current of the photoelectric conversion unit with respect to the amount of incident light. Therefore, in this type of solid-state imaging device, it is one of the important factors for improving the sensitivity to reliably introduce the incident light into the photoelectric conversion unit 23. For this purpose, an on-chip lens 27 is usually formed on the photoelectric conversion unit 23, thereby collecting light at the photoelectric conversion unit 23.

[0004]

Since the above-mentioned on-chip lens 27 is formed by removing the solvent by deforming the photoresist and baking it, the on-chip lens 27 is soft and easily scratched.
Further, since the on-chip lens has a high moisture absorption property, a high humidity resistance is required for a package for housing the solid-state imaging device chip, and an expensive lens is required.

In addition, since the on-chip lens is formed by applying heat to the photoresist and deforming the photoresist, if it comes too close to the adjacent on-chip lens, the on-chip lens comes in contact with the lens and the light-collecting performance is reduced. Also had to be spaced so that they did not come into contact. For this reason, a portion that cannot be condensed occurs between the on-chip lenses, and the sensitivity is reduced accordingly. Further, in the case of a solid-state imaging device in which the vertical and horizontal lengths of the pixels are different, since the curvature of the on-chip lens is different between the vertical direction and the horizontal direction, the focus is not fixed at one place and the sensitivity is lowered.

In a conventional CCD solid-state imaging device,
When a bright subject is imaged, a phenomenon called smear may occur in which a white tail is formed in the vertical direction of the image. FIG. 19 is a diagram for explaining the occurrence of smear. In FIG. 19, the charge transfer unit 28 which is omitted in FIG. 18B is added in order to easily explain the occurrence of smear. In FIG. 19, the vertically incident light c contributes to the photoelectric conversion. However, the obliquely incident light d is reflected multiple times between the substrate 22 and the light-shielding film 25 and leaks into the charge transfer unit 28, and the light e obliquely incident on the light-shielding film 25 is When the light-shielding property is deteriorated, it leaks into the charge transfer section 28, and they generate smear.

Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art. The object of the present invention is to firstly make it possible for light incident on a solid-state image pickup device without using an on-chip lens. The second object is to improve the rate of entering the photoelectric conversion unit, and secondly, to suppress the occurrence of smear.

[0008]

According to the present invention, there is provided a solid-state imaging device comprising: a plurality of photoelectric conversion portions regularly formed in a surface region of a semiconductor substrate; and each of the photoelectric conversion portions surrounds the photoelectric conversion portion. Partition, and a solid-state imaging device having a transparent film formed in a region defined by the partition, wherein the transparent film is stepwise or at least partially cross-sectional as it separates from the partition. It is characterized in that the refractive index increases continuously. Further, the method for manufacturing a solid-state imaging device according to the present invention includes: (1) a step of forming a large number of photoelectric conversion units on a substrate; (3) a step of forming a first partition wall forming film on the insulating film; and (4) a step of partially removing the first partition wall forming film on the photoelectric conversion unit and forming a taper on the photoelectric conversion unit. Forming a shaped opening;
(5) a step of forming a reflective film on the insulating film and the first partition wall forming film; (6) a step of removing at least the reflective film on the photoelectric conversion unit; (7) the reflective film Forming a transparent film having a higher refractive index continuously or stepwise toward the center in at least a part of the cross-section on the photoelectric conversion portion surrounded by It is characterized by.

[0009]

Next, an embodiment of a solid-state imaging device according to the present invention will be described with reference to the drawings. FIG. 1A is a plan view of the solid-state imaging device according to the first embodiment, and FIG. 1B is a cross-sectional view taken along a line AA ′ in FIG. As shown in FIGS. 1A and 1B, in the solid-state imaging device according to the first embodiment of the present invention, a photoelectric conversion unit 2 is formed in a surface region of a silicon substrate 1,
An insulating film 3 is formed on the entire surface of the silicon substrate 1 and the photoelectric conversion unit 2. Although not shown, it should be understood that necessary electrodes and wires are formed on the insulating film 3 and are covered with the insulating film. A partition forming film 4 having an inclined structure is formed on the insulating film 3 excluding the light receiving portion of the photoelectric conversion portion 2. An opening is formed on the light receiving portion of the photoelectric conversion portion 2 on the partition forming film 4. And a reflective film 5 having an inclined portion 7 around the opening. Then, a cover film 6 is formed on the insulating film 3 and the reflective film 5 on the light receiving unit of the photoelectric conversion unit 2. The cover film 6 is formed such that its refractive index gradually increases as the cover film 6 moves away from the reflection film 5.

Next, a method of manufacturing the solid-state imaging device according to the first embodiment will be described with reference to FIGS. 2 (a) to 4 (b). First, as shown in FIG. 2A, the second conductivity type impurity is introduced into the surface of the first conductivity type silicon substrate 1 to form the second conductivity type photoelectric conversion unit 2. Next, an insulating film 3 is formed on the entire surface. In an actual solid-state imaging device, the silicon substrate 1
Various kinds of diffusion layers are formed in the surface region, and various kinds of electrodes and wirings are formed on the insulating film 3. For example, in a CCD type solid-state imaging device which is currently most widely used, a charge transfer portion, an element isolation region, an insulating film 3
Although a charge transfer electrode and the like are formed thereon, they have no special features in the present invention, so that illustration and description thereof are omitted.

Next, as shown in FIG.
A partition forming film 4 of 10 to 10 μm is deposited. Since the partition wall forming film 4 is formed to be considerably thick as a film of a semiconductor device, when the stress is large, there is a possibility that the film may crack or a stress may be applied to the surface of the underlying silicon substrate 1 to deteriorate the electrical characteristics. It is better to avoid such materials. Further, in an etching step performed in a later step, it is preferable that the etching step be large in selectivity with respect to a photoresist or an underlying insulating film 3 and be easy to process. In this embodiment, amorphous silicon is used. However, if the material satisfies the above conditions, instead of amorphous silicon,
It can be adopted as appropriate. Next, a photoresist film 8 having an opening 9 is formed on the portion where the opening is to be formed on the photoelectric conversion unit 2 by a photolithography technique.

Next, as shown in FIG. 3A, using the photoresist film 8 as a mask, the partition wall forming film 4 in a portion below the opening 9 is formed.
Is etched. At this time, side etching is performed by controlling the gas flow rate, energy, and the like of the etcher, and the opening 10 having a tapered shape is formed in the side wall portion. At this time, the inclination angle of the tapered side surface with respect to the silicon substrate surface is preferably about 45 ° to 80 °.

Next, after removing the photoresist film 8, as shown in FIG. 3B, a reflection film 5 is formed on the entire surface. When the light-shielding property of the reflection film 5 is reduced, various elements formed in the silicon substrate 1, in the case of a CCD type solid-state image pickup element, light leaks directly to the charge transfer section to cause smear and the like, leading to deterioration of characteristics. When the reflectance decreases, the amount of light incident on the photoelectric conversion unit 2 decreases, and the sensitivity decreases. For this reason, the material of the reflection film 5 is preferably a material having a large light-shielding property, such as aluminum or tungsten, and a high reflectance. In addition, it is better that the side wall portion has good coverage,
A low pressure CVD (chemical vapor deposition) method or the like may be used as appropriate. In addition, the thickness is set so as to obtain a sufficient light-shielding property. For example, in the case of aluminum, at least about 100 nm is required.

Next, an opening is formed in the reflective film 5 formed on the entire surface at a position corresponding to the light receiving section of the photoelectric conversion section 2.
First, as shown in FIG. 4A, a photoresist film 11 is applied and an opening 12 slightly wider than the opening forming portion 13 is formed in the opening. Next, the reflection film 5 is etched by an anisotropic etching method. Thereby, the reflection film 5 on the insulating film 3 is removed, and the reflection film 5 on the tapered surface is removed.
Remains slightly etched. The film thickness of the reflection film 5 may be selected so that the film thickness after the etching has a sufficient light-shielding property.

Next, after removing the photoresist film 11, a cover film 6 whose refractive index gradually increases is deposited and the surface is flattened (FIG. 4B). The planarization may be performed by, for example, a CMP method (chemical mechanical polishing method) or a coating film. The cover film 6 is formed by gradually increasing the refractive index while adding a dopant. The large section defined by the dotted line in FIG.
The middle and small parts are large in refractive index schematically shown,
These are the middle and small cover films. As shown in FIG. 4B, the cover film 6 not only protects the surface of the element, but also has a function of the refractive index of the light of the cover film.
Can be refracted downward, and can be incident on the photoelectric conversion unit 2 at an angle closer to the vertical, and the sensitivity can be improved. Thus, the solid-state imaging device according to the first embodiment shown in FIGS. 1A and 1B is completed. Of course, the condensing property may be further improved by using a conventionally used on-chip lens. Further, the partition wall forming film 4 may be made reflective and the reflective film 5 may be omitted.

FIG. 5A is a plan view of a solid-state imaging device according to a second embodiment of the present invention, and FIG.
FIG. 5B is a cross-sectional view taken along line -A ′, and FIG.
(A) to FIG. 8 show. As shown in FIG. 5A, in the solid-state imaging device according to the second embodiment of the present invention, the photoelectric conversion unit 2
Is formed so as to surround the second partition wall forming film 16 indicated by the dotted line. Further, as shown in FIG. 5B, the second partition wall forming film 16 is formed vertically on the insulating film 3. The reflective film 5 covers the upper part of the second partition wall forming film 16, and the reflective film 5 is formed on the light receiving part of the photoelectric conversion part so as to cover the tapered part of the partition wall forming film 4.

A method for manufacturing a solid-state imaging device according to a second embodiment of the present invention will be described with reference to FIGS. In the manufacturing method according to the second embodiment, the steps up to depositing the partition wall forming film 4 are the same as those described in the manufacturing method according to the first embodiment, and a description thereof will be omitted.

After depositing the partition wall forming film 4, the film 4 is etched using a photoresist or the like as a mask to form a groove 15 (FIG. 6A). Next, the second partition wall forming film 1 is formed on the entire surface.
6 are buried and the groove 15 is buried [FIG. 6 (b)]. The second partition wall forming film 16 is required to have resistance to the etching of the partition wall forming film 4 to be performed next, and to be able to embed the narrow and deep groove 15 without voids. For example, silicon oxide or silicon nitride may be deposited by a low pressure CVD method.

Next, as shown in FIG. 7A, the second partition wall forming film 16 on the upper surface is removed. Subsequently, a photoresist film 8 having an opening 9 is formed in a portion of the partition wall forming film 4 above the light receiving portion of the photoelectric conversion portion 2. Next, etching is performed while adjusting the anisotropy of the partition wall forming film 4 using the photoresist film 8 as a mask. At this time, since the second partition wall forming film 16 is not etched, the lower part of the second partition wall forming film 16 is covered by the tapered partition wall forming film 4 as shown in FIG. On the light receiving portion, the partition wall forming film 4 is entirely etched and exposed.

Subsequently, after removing the photoresist film 8, the reflection film 5 is deposited. Then, after forming the opening 12 in the photoresist film 11 as in the first embodiment, etching is performed to remove the reflective film on the light receiving portion of the photoelectric conversion portion 2 (FIG. 8). Next, after removing the photoresist film 11, a cover film 6 whose refractive index is gradually increased is deposited, and FIG.
5A and 5B, the solid-state imaging device according to the second embodiment is completed. The second manufactured by the above manufacturing method
In the solid-state imaging device according to the embodiment, the area of the reflection film 5 formed on the flat portion can be reduced, whereby the amount of light incident on the light receiving unit of the photoelectric conversion unit 2 can be increased. The sensitivity of the device can be improved.

FIG. 9A is a plan view of a solid-state imaging device according to a third embodiment of the present invention, and FIG.
FIG. 9B is a cross-sectional view taken along line -A '. FIG. 9 (a)
As shown in FIG. 2, in the present embodiment, the second partition wall forming film 1 indicated by a dotted line is surrounded by each photoelectric conversion unit 2.
6. A third partition wall forming film 17 is formed. The structural difference of the present embodiment from the second embodiment appears in the cross-sectional view, and as shown in FIG. The head is not covered with the reflective film 5. In the second embodiment, as described with reference to FIG. 8, the opening of the reflection film 5 on the light receiving portion of the photoelectric conversion unit 2 is formed by masking the reflection film 5 with the photoresist film 11. It was done by etching, but the third
In the solid-state imaging device according to the embodiment, anisotropic etching is performed without using a photoresist.

Thus, an opening can be formed on the light receiving portion of the photoelectric conversion portion 2 in a self-aligned manner, and it is not necessary to form a photoresist patterned on a portion having a large base step, thereby reducing the number of steps. . However, since the reflective film 5 is etched not only on the photoelectric conversion unit 2 but also on the upper part of the partition, when a film having a low light-shielding property is used for the partition, light leaks into the silicon substrate 1 and the CCD solid-state imaging device is used. Generates noise such as smear. For this reason, when low noise is required, it is necessary to separately provide a light-blocking film (not shown) under the partition or to provide the partition with light-blocking. The partition may be formed by burying a film having a light-shielding property such as a metal in the groove. However, since the groove has a large aspect ratio, a void may be generated without filling the bottom.
In this case, a silicon oxide film or the like may be buried in the lower part of the partition wall by using a low-pressure CVD method having good burying property, and may be buried in the upper part of the partition wall by a film having a light shielding property.

An example of a method for manufacturing a solid-state imaging device according to the third embodiment will be described with reference to FIGS. 10 (a) to 11 (b). In the first step, as described in the second embodiment, after forming the groove 15 in the partition wall forming film 4 formed on the silicon substrate 1 and the insulating film 3 on the photoelectric conversion unit 2, the second partition wall forming The groove 15 is buried with the film 16 [FIG.
(A)]. Next, the second partition wall forming film 16 is etched. At this time, the second partition wall forming film 16 on the partition wall forming film 4 is removed, and the second partition wall forming film 16 in the groove is also removed to some extent.
For example, etching is performed up to about 1 to 3 μm from the surface of the insulating film 3. Next, as shown in FIG.
A third partition wall forming film 17 having a light shielding property is deposited on the entire surface of the partition wall forming film 4 and the second partition wall forming film 16. The third partition wall forming film is preferably made of, for example, aluminum or tungsten.

Next, the third partition wall forming film is removed by anisotropic etching except for the groove portion surrounded by the partition wall forming film 4 shown in FIG. Next, as in the second embodiment, a mask pattern using the photoresist film 8 is formed, and the partition wall forming film 4 is etched to obtain the structure shown in FIG. Next, as shown in FIG. 11B, after removing the photoresist film 8, a reflection film 5 is deposited. Next, etching is performed until the portion of the reflection film 5 on the light receiving unit of the photoelectric conversion unit 2 is removed, and then the cover film 6 is formed as shown in the first embodiment. The solid-state imaging device according to the third embodiment shown in FIGS. 9A and 9B is obtained.

FIG. 12A is a plan view of a solid-state imaging device according to the fourth embodiment, and FIG.
FIG. 12B shows a cross section at A ′, and FIGS. 13A to 13B show cross-sectional views in the order of steps of the manufacturing method. 4th
As shown in FIG. 12A, the solid-state imaging device according to the embodiment has a transparent film 1 having a different refractive index on a light receiving portion of the photoelectric conversion portion 2.
8, 19, and 20. In addition, as shown in FIG. 12B, the light receiving section of the photoelectric conversion section 2 is surrounded by the partition formed by the partition forming films 16 and 17. And on the photoelectric conversion unit,
The transparent films 18, 19, and 20 are embedded such that the refractive index gradually increases from the end of the light receiving unit of the photoelectric conversion unit toward the center,
Further, the upper part is flattened.

Next, a manufacturing method according to a fourth embodiment will be described. The method for forming a transparent film having a different refractive index according to the fourth embodiment can be applied to any of the first to third embodiments described above, but is applied to the third embodiment here. An example is shown below. The manufacturing method of the fourth embodiment up to the formation of the reflection film 5 shown in FIG. 13A is the same as the manufacturing method of the solid-state imaging device of the third embodiment shown in FIG. Therefore, the description is omitted. After forming the reflection film 5 shown in FIG. 13A and removing the reflection film on the light receiving portion of the photoelectric conversion unit 2 and the third partition wall forming film by etching in the same manner as in the third embodiment, the transparent film is formed. 18, 19, and 20 are sequentially deposited. The refractive indices of the transparent films 18 to 20 are made higher as later. Here, three films with clearly defined boundaries are shown, but any number of two or more films may be used, and a larger number of films is preferable. FIG. 13B shows a cross-sectional view at this time.
Next, the upper portion is polished by a CMP method or the like to flatten the upper portion.
Thus, the solid-state imaging device according to the fourth embodiment shown in FIGS. 12A and 12B is completed.

The transparent films 18 to 20 are arranged so that the refractive index becomes higher toward the center of the tapered inverted cone. The light b obliquely incident from the film having a high refractive index to the film having a low refractive index is refracted in the direction of the light receiving unit of the photoelectric conversion unit 2 as shown in FIG. As a result, the light is incident on the photoelectric conversion unit at an angle close to the vertical, and the sensitivity is improved. In the case of a CCD solid-state imaging device, there is an effect that smear is reduced.

FIG. 14A is a plan view of the solid-state imaging device according to the fifth embodiment, and FIG.
FIG. 14B shows a cross section at A ′, and FIGS. 15A to 16 show cross-sectional views in the order of steps of the manufacturing method. FIG.
In the structure of the solid-state imaging device according to the fifth embodiment shown in (a) and (b), a transparent film 1 having a different refractive index is formed on a photoelectric conversion unit 2.
8, 19, and 20. A characteristic difference from the fourth embodiment is that, as shown in the cross-sectional view of FIG.
The upper part of the third partition wall forming film 17 and the reflective film 5 sandwiching the film 17 is sharpened. With this structure, light is not reflected upward at this portion, the amount of incident light is increased, and the sensitivity is improved.

This embodiment in which the upper part of the partition is sharpened can be applied to any of the second to fourth embodiments described above.
Here, an example applied to the fourth embodiment is shown. First, as shown in FIG. 13A of the fourth embodiment,
The partition wall forming films 16 and 17 are formed (the previous step is the same as the step described in the fourth embodiment, and thus the description is omitted). At this time, as shown in FIG. The portion of the third partition wall forming film that is not covered by the partition wall forming film 4 is increased (that is, the third partition wall forming film 17 of FIG. 15A is longer in the vertical direction than that of FIG. 13A). Long). Next, the transparent films 18, 19 and 20 are formed after removing the photoelectric conversion portion and the reflective film 5 above the partition walls by etching in the same manner as in the fourth embodiment (FIG. 15B).

Next, polishing is performed by the CMP method (FIG. 1).
6). Next, the exposed transparent films 18, 19, 20, the third partition wall forming film, and the reflective film 5 are etched. At this time, by changing the ratio of the etching rates of the transparent films 18, 19, and 20, the third partition wall forming film 17, and the reflective film 5, the third
The inclination of the upper part of the partition wall formed by the partition wall forming film 17 and the reflection film 5 can be changed. For example, (Transparent film 1
If the etching rate of 8, 19, and 20) (the etching rate of the third partition wall forming film and the reflective film 5) is set to 5: 1, the inclination of the partition wall with respect to the horizontal plane (tangent of the angle between the sharp partition wall and the horizontal plane) is 5 Can be Thus, the solid-state imaging device according to the fifth embodiment of the present invention shown in FIGS. 14A and 14B can be obtained.

Next, FIG. 17A is a plan view of a solid-state imaging device according to the sixth embodiment, and FIG. 17B is a cross-sectional view taken along a line AA ′ in FIG. Show. FIG.
As shown in FIG. 17A and FIG. 17B, the sixth embodiment uses a transparent film having a different refractive index and an on-chip lens 21 instead of using a reflective film. According to the manufacturing method of the sixth embodiment, after forming a partition wall using a third partition wall forming film having a light shielding property, transparent films 18, 19, and 20 are deposited in order from a lower refractive index to a higher refractive index.
Polishing by MP method. Next, an on-chip lens 21 is formed to complete the solid-state imaging device according to the sixth embodiment shown in FIGS. 17A and 17B. According to the solid-state imaging device of the sixth embodiment formed in this way, the light-collecting effects of the transparent films 18, 19, and 20 and the on-chip lens 21 having different refractive indexes are added, and the solid-state imaging device with higher sensitivity Is obtained.

Although the preferred embodiments have been described above, the present invention is not limited to these embodiments, and can be appropriately modified within the scope described in the claims. For example, in the step of depositing the transparent film (a), it has been described that the film is deposited continuously, but the refractive index of the film may be increased while repeating deposition and etchback. Thereby, a film having a high refractive index can be concentrated on the central portion of the photoelectric conversion portion, and the light collecting property can be further improved. The present invention also relates to the CC
The present invention can be applied to all solid-state imaging devices having a photoelectric conversion unit including a D-type solid-state imaging device, a MOS-type solid-state imaging device, and the like.

[0033]

As described above, in the solid-state imaging device of the present invention, the transparent film (cover film) whose refractive index gradually or stepwise decreases from the center of each photoelectric conversion portion toward the outside. Since it is formed, according to the present invention, it is possible to obtain a solid-state imaging device with improved sensitivity by increasing the rate at which light incident on the solid-state imaging device enters the photoelectric conversion unit. Also,
In the embodiment in which the on-chip lens is not used, since the element surface is covered with the hard cover film, the case can be simplified and the cost can be reduced. Also, C
In the CD-type solid-state imaging device, the occurrence of smear can be suppressed by reducing the light incident on the charge transfer unit.

[Brief description of the drawings]

FIG. 1 is a plan view and a cross-sectional view of a first embodiment.

FIG. 2 is a cross-sectional view of a first embodiment in the order of steps (part 1).

FIG. 3 is a step-by-step cross-sectional view of the first embodiment (part 2).

FIG. 4 is a step-by-step sectional view of the first embodiment (part 3).

FIG. 5 is a plan view and a cross-sectional view of a second embodiment.

FIG. 6 is a step-by-step cross-sectional view of the second embodiment (No. 1).

FIG. 7 is a step-by-step cross-sectional view of the second embodiment (No. 2).

FIG. 8 is a step-by-step sectional view of the second embodiment (No. 3).

FIG. 9 is a plan view and a cross-sectional view of a third embodiment.

FIG. 10 is a step-by-step sectional view of the third embodiment (No. 1).

FIG. 11 is a step-by-step cross-sectional view of the third embodiment (No. 2).

FIG. 12 is a plan view and a cross-sectional view of a fourth embodiment.

FIG. 13 is a sectional view of a fourth embodiment in the order of steps.

14A and 14B are a plan view and a cross-sectional view of the fifth embodiment.

FIG. 15 is a step-by-step cross-sectional view of the fifth embodiment (No. 1).

FIG. 16 is a step-by-step cross-sectional view of the fifth embodiment (No. 2).

17A and 17B are a plan view and a cross-sectional view of the sixth embodiment.

FIG. 18 is a plan view and a cross-sectional view of a conventional example.

FIG. 19 is a diagram illustrating generation of smear.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Silicon substrate 2 Photoelectric conversion part 3 Insulating film 4 Partition formation film 5 Reflection film 6 Cover film 7 Inclined part 8 Photoresist film 9 Opening 10 Opening 11 Photoresist film 12 Opening 13 Opening formation part 15 Groove 16 Second partition formation film 17 Third partition wall forming film 18 Transparent film 19 Transparent film 20 Transparent film 21 On-chip lens 22 Substrate 23 Photoelectric conversion unit 24 Insulating film 25 Light-shielding film 26 Transparent flat film 27 On-chip lens 28 Charge transfer unit

Claims (12)

[Claims] 1. A large number of photoelectric conversion units regularly formed in a surface region of a semiconductor substrate; a partition wall surrounding the photoelectric conversion unit for each photoelectric conversion unit; and a partition defined by the partition wall. And a formed transparent film, wherein the transparent film has a refractive index that increases stepwise or continuously as the transparent film moves away from the partition wall in at least a part of the cross section. Solid-state imaging device. 2. The solid-state imaging device according to claim 1, wherein the partition has a reflection function, or a reflection film is formed on a surface of the partition. 3. The solid according to claim 1, wherein the partition wall is formed so that its cross-sectional shape becomes thicker as approaching the semiconductor substrate, and its side surface has an inclination. Imaging device. 4. The partition according to claim 1, wherein the partition is a first partition defining a light receiving region of a photoelectric conversion unit, and a second partition disposed at the first central portion.
The solid-state imaging device according to any one of claims 1 to 3, wherein the solid-state imaging device comprises: 5. The solid-state imaging device according to claim 4, wherein said second partition is formed by a two-layer film of a lower film having a good embedding property and an upper film having an excellent light-shielding property. 6. The solid-state imaging device according to claim 4, wherein an upper side surface of said second partition is not covered by said first partition. 7. The solid-state imaging device according to claim 4, wherein the head of the second partition is pointed. 8. The solid-state imaging device according to claim 1, further comprising an on-chip lens on the transparent film on the photoelectric conversion unit. 9. A process for forming a large number of photoelectric conversion units on a substrate, a process for forming an insulating film on the substrate and the photoelectric conversion unit, and a process for forming an insulating film on the substrate and the photoelectric conversion unit. Forming a first partition wall forming film; and (4) forming a tapered opening on the photoelectric conversion unit by partially removing the first partition wall forming film on the photoelectric conversion unit. (5) forming a reflective film on the insulating film and the first partition wall forming film; (6) removing the reflective film on at least the photoelectric conversion unit; Forming a transparent film having a higher refractive index continuously or stepwise toward the center in at least a part of the cross section on the photoelectric conversion portion surrounded by the film. A method for manufacturing a solid-state imaging device. 10. A process for forming a plurality of photoelectric conversion portions on a substrate, a process for forming an insulating film on the substrate and the photoelectric conversion portion, and a process for forming an insulating film on the substrate and the photoelectric conversion portion. Forming a first partition wall forming film on the film; (4 ') forming a groove having a shape surrounding each of the photoelectric conversion units by partially removing the first partition wall forming film; ′) Burying a second partition wall forming film in the groove to form a second partition wall; and (6 ′) removing the first partition wall forming film on the photoelectric conversion section and removing the photoelectric conversion section. (7 ') forming a reflective film on the entire surface; (8') removing the reflective film on the photoelectric conversion unit; (9 ') On the photoelectric conversion portion surrounded by the reflective film, the younger portion is continuously younger toward the center in at least a part of the cross section. Stepwise method for manufacturing a solid-state imaging device having a step of forming a transparent film having a refractive index is high. 11. In the step (6) or the step (8 ′), etching is performed using a photoresist film having an opening on the photoelectric conversion portion as a mask or without passing through a mask. The method for manufacturing a solid-state imaging device according to claim 9, wherein: 12. The method according to claim 9, wherein the step (7) or the step (9 ′) includes a step of repeating deposition of a transparent film and etching back. A method for manufacturing the solid-state imaging device according to the above.