JP2011222572A - Solid-state imaging element, method of manufacturing the same and electronic information apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form an insulator film in a gap between transfer electrodes without causing the deterioration of pixel characteristics.SOLUTION: During a thermal oxidation treatment, a silicon nitride film is embedded in a gap G between charge transfer electrodes as a thermal oxidation barrier film. The gap G between charge transfer electrodes and an opening 8b on the upper side of a light receiving portion 5 that is a photoelectric conversion portion are formed at the same time. In addition, a third insulator film 11 that is thinner and stable is formed as a result of thermal oxidation of a surface of the light receiving portion 5, a p-type impurity ion is injected in a surface portion of the light receiving portion 5 of an n-type semiconductor substrate 1 through this third insulator film 11 that is thin and stable, and a high-concentration surface p+ layer is formed. Furthermore, a second insulator film 10 is removed from within the gap G and a fourth insulator film 12 is embedded in the gap G again. The insulator film to be embedded in the gap G between charge transfer electrodes (the fourth insulator film 12) and a reflection suppression film on the light receiving portion 5 (the fourth insulator film 12) are manufactured in the same process with the same materials.

Description

  The present invention relates to a solid-state imaging device composed of a semiconductor element that images image light from a subject by photoelectric conversion, and a method for manufacturing the solid-state imaging device. Regarding a solid-state imaging device manufactured by a manufacturing method, for example, a digital camera such as a digital video camera and a digital still camera using the solid-state imaging device as an image input device in an imaging unit, an image input camera such as a surveillance camera, a scanner device, The present invention relates to an electronic information device such as a facsimile apparatus, a television telephone apparatus, and a camera-equipped mobile telephone apparatus.

  In recent years, solid-state imaging devices have been increasing in number of pixels, and as the number of pixels increases, it is necessary to transfer signal charges at a high speed. In particular, the resistance of the charge transfer electrodes is reduced and the gap between the charge transfer electrodes is miniaturized. Has become important.

  The gap between the charge transfer electrodes needs to be narrowed to make the potential in the transfer channel uniform. Conventionally, after forming a gap between charge transfer electrodes, a conductive film such as polysilicon which is a charge transfer electrode is oxidized to form an insulating film between the charge transfer electrodes. In this thermal oxide film forming method, The surface of the transfer channel and the conductive film such as polysilicon are eroded by thermal oxidation to form a smiley shape and the gap between the charge transfer electrodes widens, which not only hinders device miniaturization, but also the width of the charge transfer electrode. As a result, the potential in the transfer channel cannot be made uniform, thereby forming a region where the transfer pulse to the transfer channel is difficult to be applied locally. There was a problem.

  Therefore, Patent Document 1 discloses a method of forming an insulating film without expanding the gap between charge transfer electrodes by filling the gap between charge transfer electrodes with an insulating film by LPCVD without performing thermal oxidation. It is disclosed.

  The manufacturing method in Patent Document 1 will be briefly described. First, a gate insulating film and polysilicon as a gate electrode are formed on a silicon substrate, and a resist pattern having an opening in a gap between charge transfer electrodes is formed. Then, using this as a mask, the polysilicon is etched to form a gap between the charge transfer electrodes. Thereafter, an insulating film is formed in the gap between the charge transfer electrodes so as to fill the gap portion by forming a silicon oxide film (HTO) or a silicon nitride film by LPCVD.

  12 (a) to 12 (c), FIG. 13 (a), and FIG. 13 (b) are main parts showing respective manufacturing steps of the conventional method for manufacturing a solid-state imaging device disclosed in Patent Document 1. It is a longitudinal cross-sectional view.

As shown in FIG. 12A, as a conventional method for manufacturing a solid-state imaging device, a low-pressure CVD method using SiH ₄ diluted with He as a reactive gas on a gate oxide film 102 on the silicon substrate 101 is used. Then, a polycrystalline silicon film having a thickness of 0.4 μm is formed. The substrate temperature at this time is 600 to 700 degrees Celsius. Thereafter, heat treatment is performed at 900 degrees Celsius in a mixed gas atmosphere of POCl ₃ , N _2, and O ₂ to dope the polycrystalline silicon film 103 (phosphoric acid treatment).

  Subsequently, a positive resist is applied to the upper layer so as to have a thickness of 0.5 to 1.4 μm. As shown in FIG. 12B, exposure is performed by photolithography using a desired mask, development and washing are performed to form a resist pattern R1 having an opening width g = 0.2 μm.

Thereafter, as shown in FIG. 12C, silicon nitride of the gate oxide film 102 is formed by reactive ion etching using a mixed gas of HBr and O ₂ or HBr and Cl ₂ using the resist pattern R1 as a mask. Using the film 102b as an etching stopper, the polycrystalline silicon film 103 is selectively removed by etching to form an electrode pattern. Here, it is desirable to use an etching apparatus such as ECR or ICP. Here, the resist pattern R1 is removed by ashing.

Further, as shown in FIG. 13A, the interelectrode insulating film 104 made of a silicon oxide film (HTO) having a thickness of 80 nm is formed on the surface of the pattern of this electrode by a low pressure CVD method using monosilane and N ₂ O. Form. Here, the substrate temperature was maintained at 750 degrees Celsius, and the pressure in the film formation chamber was 1.2 Torr.

Thereafter, as shown in FIG. 13B, an insulating film 105 made of a silicon nitride film is formed so as to cover the entire interelectrode insulating film 104 by a low pressure CVD method using NH ₃ and DCS (SiH ₂ Cl ₂ ). Form.

Next, a resist is applied, a resist pattern having an opening is formed in a photodiode formation region which is a photoelectric conversion portion by photolithography, and a mixed gas of HBr and O ₂ or HBr and Cl ₂ using the resist pattern as a mask An opening is formed on the photodiode formation region by reactive ion etching using.

  Thereafter, the resist pattern is left as it is, and ion implantation for forming a pn junction of the photodiode is performed using the resist pattern as a mask, thereby forming a diffusion region for forming a pn junction with the silicon substrate 101. The pn junction forms a photoelectric conversion unit as a light receiving unit.

  Thus, an electrode pattern is formed so as to have a narrow gap interelectrode region, and an interelectrode insulating film made of a silicon oxide film is formed between the electrode patterns by a low pressure CVD method. Here, the width g of the interelectrode region is 0.2 μm, and the interelectrode insulating film 104 made of a silicon oxide film having a good film quality is formed in this narrow interelectrode region by low pressure CVD. Here, in order to form an opening having a fine width, an opening is formed in the resist film by photolithography, an organic material is applied, and thermosetting is performed by heat treatment, whereby a thermosetting layer is formed on the surface of the resist film. The size of the opening is reduced, and the fine opening is formed to form a fine opening with a fine width exceeding the resolution limit. A charge transfer electrode having a fine gap can be formed with high accuracy.

JP 2004-335804 A

  In the conventional method for manufacturing a solid-state imaging device, only the gap between the charge transfer electrodes (the width g of the interelectrode region) is formed, an insulating film is embedded therein, and then the opening above the photoelectric conversion unit that is the light receiving unit is formed. Processing. If the gap between the charge transfer electrodes and the opening above the photoelectric conversion part are formed simultaneously, an insulating film for filling the gap is attached to the side wall of the opening above the photoelectric conversion part, and the opening width becomes narrow. For this reason, the formation of the gap between the charge transfer electrodes and the opening above the photoelectric conversion portion is performed in separate steps. As described above, since the alignment accuracy varies when forming the opening above the photoelectric conversion portion because of a separate process, the opening for forming the photoelectric conversion portion overlaps to the gap between the charge transfer electrodes. In this case, the insulating film in the gap portion between the charge transfer electrodes is removed during the polysilicon etching, the silicon substrate itself is etched, unnecessary ion implantation is performed, and a leak occurs. As a result, there is a problem that pixel characteristics such as light receiving sensitivity deteriorate.

  Further, in the conventional method for manufacturing a solid-state imaging device, the resist pattern used for the opening of the photoelectric conversion portion is left as it is, and this is used as a mask to perform the surface P + implantation of the photodiode. Since this ion implantation is performed over the base residual film after etching of the gate electrode, the depth and concentration of impurity ion implantation in the silicon substrate fluctuate when the etching residual film varies. There is a problem in that stable light receiving sensitivity cannot be obtained and pixel characteristics deteriorate.

  Furthermore, in the conventional general solid-state imaging device manufacturing method, in order to suppress the generation of reflected light in the light receiving unit (photoelectric conversion unit) and prevent image quality disturbance due to re-incidence of the reflected light, An antireflection film (low reflection film) made of a silicon nitride film is provided. When this is applied to the above-described conventional manufacturing method, it is necessary to form the buried insulating film in the gap portion between the charge transfer electrodes and the antireflection film on the light receiving portion in separate steps. For this reason, the cost increases, an interlayer film is formed on the gate electrode more than necessary, and the distance between the lens and the substrate increases due to an increase in the surface of the light shielding film. There is a problem that the light receiving sensitivity deteriorates.

  The present invention solves the above-mentioned conventional problems, and does not cause deterioration of various pixel characteristics such as charge transfer failure, reduction of light receiving area, and deterioration of light receiving sensitivity, and an insulating film is formed in the gap between transfer electrodes. It is an object to provide a method for manufacturing a solid-state image pickup device capable of performing image processing, and an electronic information device such as a camera-equipped mobile phone device using the solid-state image pickup device manufactured by the method for manufacturing a solid-state image pickup device as an image input device in an image pickup unit. And

  In the method for manufacturing a solid-state imaging device according to the present invention, a conductive film formed on a semiconductor substrate via a gate insulating film is patterned to form a gap portion on the charge transfer portion, and to pick up incident light. A charge transfer electrode forming step of forming charge transfer electrodes each having an opening above the light receiving portion, and a first insulating film is formed on the charge transfer electrode and on the gate insulating film including the gap portion. A first insulating film forming step; a second insulating film forming step of forming a second insulating film on the first insulating film; and the second insulating film in the gap portion is left. An etch-back process for removing each insulating film until the upper surface of the substrate and the upper surface of the charge transfer electrode are exposed, and the upper surface of the substrate and the upper surface of the charge transfer electrode. A third insulating film is formed by thermal oxidation on the third insulating film. And a fourth insulating film forming step of forming a fourth insulating film on the entire surface of the substrate after removing the second insulating film in the gap portion. Achieved.

Preferably, the first insulating film forming step in the method for manufacturing a solid-state imaging device according to the present invention is a silicon oxide film having a predetermined thickness at a predetermined temperature using SiH ₄ gas and N ₂ O by LPCVD. Is formed as the first insulating film.

Further preferably, the second insulating film forming step in the method for manufacturing a solid-state imaging device of the present invention is performed by using a SiH ₂ CL ₂ gas and an NH ₃ gas by LPCVD, and silicon having a predetermined film thickness at a predetermined temperature. A nitride film is formed as the second insulating film.

  Further preferably, in the method of manufacturing a solid-state imaging device according to the present invention, in the etch back step, the entire surface of the light receiving unit is etched back until the first insulating film is exposed to the second insulating film. And a second insulating film removing step of leaving the second insulating film in the gap while removing the second insulating film on the surface side of the charge transfer electrode, and a substrate surface above the surface of the light receiving portion Removing the first insulating film and the gate insulating film until the upper surface of the charge transfer electrode is exposed, and removing the first insulating film until the upper surface of the charge transfer electrode is exposed. .

  Further preferably, the surface reverse is performed by ion-implanting impurities having a conductivity type opposite to the impurity conductivity type of the light receiving portion into the surface side of the light receiving portion through the third insulating film in the method for manufacturing a solid-state imaging device of the present invention. The method further includes a surface reverse conductivity type layer forming step of forming the conductivity type layer.

Further preferably, the second insulating film in the gap portion is removed by etching using phosphoric acid (H ₃ PO ₄ ) before the formation of the fourth insulating film in the method for manufacturing a solid-state imaging device of the present invention. To do.

  Still preferably, in a method for manufacturing a solid-state imaging device according to the present invention, the fourth insulating film forming step includes filling the gap in the fourth insulating film and reflecting the surface of the light receiving unit upward. The fourth insulating film as a prevention film is formed at the same time.

  Further preferably, in the method for manufacturing a solid-state imaging device of the present invention, a predetermined impurity is ion-implanted into the semiconductor substrate before the charge transfer electrode forming step, and the light receiving unit and a signal from the light receiving unit The semiconductor device further includes an impurity diffusion region forming step for forming charge transfer portions for transferring charges.

  Further preferably, in the method for manufacturing a solid-state imaging device according to the present invention, a light shielding film is formed on the fourth insulating film after the fourth insulating film forming step, and the light shielding film above the light receiving unit. A light-shielding film forming step for opening the opening.

  Further preferably, in the method for manufacturing a solid-state imaging device of the present invention, both the second insulating film and the fourth insulating film are silicon nitride films.

  Still preferably, in a method for manufacturing a solid-state imaging device according to the present invention, the first insulating film is a CVD oxide film, and the third insulating film is a thermal oxide film.

  Still preferably, in a method for manufacturing a solid-state imaging device according to the present invention, the gap portion is a gap between charge transfer electrodes.

  The solid-state imaging device of the present invention is a solid-state imaging device manufactured by the above-described method for manufacturing a solid-state imaging device of the present invention, and has a predetermined interval on the charge transfer portion via the gate insulating film on the semiconductor substrate. A charge transfer electrode made of a conductive film having an opening is provided above the gap portion and the light receiving portion, the conductive film is not eroded by thermal oxidation in the gap portion, and the gap portion has a substrate surface. The first insulating film and the fourth insulating film are embedded through the gate insulating film, and the fourth insulating film is formed on the substrate surface above the light receiving portion through the third insulating film. This achieves the above object.

  Preferably, in the solid-state imaging device of the present invention, a step is formed on the surface of the semiconductor substrate by the thermal oxide film which is the third insulating film.

  Further preferably, in the solid-state imaging device of the present invention, a buried insulating film in the gap portion between the charge transfer electrodes is constituted by the fourth insulating film, and the fourth insulating film is reflected on the light receiving portion. Also serves as a prevention film.

  The electronic information device of the present invention uses the solid-state imaging device of the present invention as an image input device in an imaging unit, and thereby achieves the above object.

  With the above configuration, the operation of the present invention will be described below.

  In the present invention, a conductive film formed on a semiconductor substrate through a gate insulating film is patterned to form a gap portion on the charge transfer portion, and above a plurality of light receiving portions for imaging incident light. Charge transfer electrode forming step for forming charge transfer electrodes each having an opening, and first insulating film forming step for forming a first insulating film on the charge transfer electrode and on the gate insulating film including the gap portion And a second insulating film forming step for forming a second insulating film on the first insulating film, and a substrate surface above the light receiving portion in a state where the second insulating film in the gap portion is left. And an etch back step of removing each insulating film until the upper surface of the charge transfer electrode is exposed, and a third insulating film is formed by thermal oxidation on the substrate surface above the light receiving portion and the upper surface of the charge transfer electrode. A third insulating film forming step and a second in the gap After removal of the Enmaku, and a fourth insulating film forming step of forming a fourth insulating film on the entire surface of the substrate. A surface reverse conductivity type layer forming step of forming a surface reverse conductivity type layer by injecting an impurity having a conductivity type opposite to the impurity conductivity type of the light receiving portion into the light receiving portion surface side through the third insulating film is further provided. Yes.

  Thereby, when the third insulating film is formed, the gap between the charge transfer electrodes is filled with the second insulating film as a thermal oxidation suppressing film, so that the surface of the transfer channel below the gap and the side wall of the charge transfer electrode Is not oxidized, and expansion of the gap between the charge transfer electrodes due to thermal oxidation as in the past is suppressed, and pixel characteristics such as charge transfer failure and reduction of the light receiving area do not deteriorate.

  In addition, since the gap between the charge transfer electrodes and the opening above the photoelectric conversion unit are simultaneously formed in one step, the process can be simplified and the gap between the charge transfer electrode and the opening above the photoelectric conversion unit can be aligned. The accuracy does not vary, and pixel characteristics such as light receiving sensitivity are not deteriorated.

  Further, since the third insulating film is thermally oxidized on the surface of the light receiving portion and the film thickness is stable, the third insulating film is opposite to the light receiving portion on the surface side in the silicon substrate through the third insulating film having a stable film thickness. Since the conductivity type impurity ions are implanted, the depth and concentration of the impurity ions do not fluctuate and the pixel characteristics such as the light receiving sensitivity are not deteriorated.

  Since the second insulating film is removed from the gap and the fourth insulating film is backfilled in the gap, the second insulating film on the gate electrode and the side wall is also removed, and the height of the gate electrode The width of the insulating film on the side wall can be minimized. In addition, since the buried insulating film in the gap between the charge transfer electrodes and the antireflection film on the light receiving part are formed in the same process, the process is simplified and an interlayer film is formed on the gate electrode more than necessary. The surface of the light shielding film is not increased. As a result, for example, the problem that the light can not be collected obliquely and the sensitivity is deteriorated as in the conventional case is solved.

  Therefore, there is no deterioration of various pixel characteristics such as charge transfer failure, reduction of the light receiving area, and deterioration of light receiving sensitivity, and an insulating film can be formed between the transfer electrodes.

  As described above, according to the present invention, when the third insulating film to be thermally oxidized is formed, the gap between the charge transfer electrodes is filled with the second insulating film as the thermal oxidation suppressing film. The surface of the transfer channel and the side wall of the charge transfer electrode are not oxidized, and expansion of the gap between the charge transfer electrodes due to conventional thermal oxidation can be suppressed, resulting in deterioration of pixel characteristics such as charge transfer failure and light receiving area reduction There is no. In addition, since the gap between the charge transfer electrodes and the opening above the photoelectric conversion unit are formed at the same time, the alignment accuracy between the gap between the charge transfer electrodes and the opening above the photoelectric conversion unit does not vary as in the past, As a result, pixel characteristics such as charge transfer failure are not deteriorated. Furthermore, the surface of the light receiving portion is thermally oxidized to form a thin and stable third insulating film, and this thin and stable third insulating film is passed through the semiconductor substrate into the semiconductor substrate opposite to the light receiving portion. Since the conductivity type impurity ions are implanted, the implantation depth and concentration of the impurity ions do not fluctuate or vary, and pixel characteristics such as light receiving sensitivity are not deteriorated. Further, since the second insulating film is removed from the gap and the fourth insulating film is backfilled in the gap, the second insulating film on the side wall of the charge transfer electrode is also removed, and the insulating film on the side wall of the gate electrode is removed. The width can be minimized. Also, if the insulating film embedded in the gap portion between the charge transfer electrodes and the antireflection film on the light receiving portion are made of the same material in the same process, an interlayer film is not formed more than necessary on the charge transfer electrode, The height of the surface of the light-shielding film is not increased as in the prior art, and the problem that sensitivity is deteriorated due to the fact that, for example, oblique condensing cannot be performed is eliminated. Therefore, there is no deterioration of various pixel characteristics such as charge transfer failure, reduction of the light receiving area, and deterioration of light receiving sensitivity, and the insulating film can be stably formed in the gap between the transfer electrodes.

It is a top view which shows the principal part structural example of the unit pixel part of the solid-state image sensor in Embodiment 1 of this invention. 1A is a cross-sectional view taken along the line AA ′ in FIG. 1, and FIG. 2B is a cross-sectional view taken along the line BB ′ in the horizontal direction in FIG. 1. FIG. 2 is a longitudinal sectional view showing an impurity diffusion region formation / gate insulating film and gate electrode material deposition step in the method for manufacturing the solid-state imaging device of FIG. 1, wherein (a) is a longitudinal sectional view taken along line AA ′ of FIG. ) Is a longitudinal sectional view taken along line BB ′ of FIG. 2A and 2B are longitudinal sectional views showing a gate electrode forming step in the method for manufacturing the solid-state imaging device in FIG. 1, wherein FIG. 1A is a longitudinal sectional view taken along line AA ′ in FIG. 1, and FIG. It is. FIG. 2 is a longitudinal sectional view showing a silicon oxide film (first insulating film) and silicon nitride film (second insulating film) film forming step in the method of manufacturing the solid-state imaging device of FIG. AA 'line longitudinal cross-sectional view, (b) is a BB' line longitudinal cross-sectional view of FIG. FIG. 2 is a longitudinal sectional view showing a silicon nitride film (second insulating film) etch-back process in the method for manufacturing the solid-state imaging device of FIG. 1, wherein (a) is a longitudinal sectional view taken along the line AA ′ of FIG. It is a BB 'line longitudinal cross-sectional view of FIG. It is a longitudinal cross-sectional view which shows the silicon oxide film (1st insulating film) and gate insulating film etching removal process in the manufacturing method of the solid-state image sensor of FIG. 1, Comprising: (a) is the AA 'line longitudinal cross-sectional view of FIG. (B) is the BB 'line longitudinal cross-sectional view of FIG. It is a longitudinal cross-sectional view which shows the silicon thermal oxide film (3rd insulating film) formation process in the manufacturing method of the solid-state image sensor of FIG. 1, Comprising: (a) is the AA 'line longitudinal cross-sectional view of FIG. It is a BB 'line longitudinal cross-sectional view of FIG. FIG. 2 is a longitudinal sectional view showing a photodiode surface P + implantation and a second insulating film removal step in the gap G in the method for manufacturing the solid-state imaging device of FIG. 1, wherein FIG. ) Is a longitudinal sectional view taken along line BB ′ of FIG. FIG. 2 is a longitudinal sectional view showing a silicon nitride film (fourth insulating film) forming step in the method for manufacturing the solid-state imaging device of FIG. 1, wherein (a) is a longitudinal sectional view taken along line AA ′ of FIG. 1, and (b) is a diagram. 1 is a longitudinal sectional view taken along line BB ′ of FIG. As Embodiment 2 of the present invention, an outline of an electronic information device using a solid-state imaging device that obtains a color image signal by performing predetermined signal processing on an imaging signal from the solid-state imaging device 20 of Embodiment 1 of the present invention as an imaging unit. It is a block diagram which shows the example of a structure. (A)-(c) is a principal part longitudinal cross-sectional view which shows each manufacturing process (the 1) of the manufacturing method of the conventional solid-state image sensor currently disclosed by patent document 1, respectively. (A) And (b) is a principal part longitudinal cross-sectional view which shows each manufacturing process (the 2) of the manufacturing method of the conventional solid-state image sensor currently disclosed by patent document 1, respectively.

  Embodiment 1 of the solid-state imaging device and manufacturing method thereof according to the present invention, and a mobile phone device with a camera, for example, using a solid-state imaging device manufactured by the manufacturing method of the solid-state imaging device as an image input device in an imaging unit Embodiment 2 of the electronic information device will be described in detail with reference to the drawings. In addition, each thickness, length, etc. of the structural member in each figure are not limited to the structure to illustrate from a viewpoint on drawing preparation.

(Embodiment 1)
FIG. 1 is a plan view illustrating a configuration example of a main part of a unit pixel unit of a solid-state imaging device according to Embodiment 1 of the present invention.

  In FIG. 1, the solid-state imaging device 20 according to the first embodiment includes a plurality of light receiving units 5 that photoelectrically convert image light from a subject and image it in a matrix form in the vertical and horizontal directions. Between the plurality of light receiving portions 5 arranged in the vertical direction and the plurality of light receiving portions 5 arranged in the vertical direction adjacent to the plurality of light receiving portions 5, a gate electrode 8 which is a charge transfer electrode in the vertical direction. The vertical CCD charge transfer unit 3 is disposed below it. A signal charge read from the light receiving unit 5 to the vertical CCD charge transfer unit 3 below either the left or right transfer gate electrode 8 is applied to the transfer gate electrode 8 by applying a predetermined transfer pulse (here, in FIG. 1). Charges are transferred along the vertical CCD charge transfer unit 3 (downward).

  2A is a cross-sectional view taken along line AA ′ in FIG. 1, and FIG. 2B is a cross-sectional view taken along line BB ′ in FIG.

  As shown in FIG. 2A, a low-concentration p-type well 2 is formed on an n-type semiconductor substrate 1 which is a silicon substrate, and a vertical CCD transfer unit 3 made of n-type impurities is formed on the p-type well 2. ing.

  A transfer gate electrode 8 having a gap portion G is formed on the surface of the n-type semiconductor substrate 1 via a gate insulating film 7. A silicon oxide film formed by CVD is used as a first insulating film 9 between the gap portions G. A silicon oxide film formed by thermal oxidation is formed on the transfer gate electrode 8 as the third insulating film 11. A light shielding film 13 such as a tungsten (W) film is provided through a fourth insulating film 12 made of a silicon nitride film formed on the upper surfaces of the first insulating film 9 and the third insulating film 11. Yes.

  A gap between the gap portions G is filled with a silicon oxide film and a silicon nitride film formed by CVD, and the gate electrode material between the gap portions G and the substrate surface under the gap G are conventionally oxidized by thermal oxidation other than the gate insulating film. There is no erosion part.

  On the other hand, as shown in FIG. 2B, a low-concentration p-type well 2 is formed in an n-type semiconductor substrate 1. Further, in the p-type well 2, there are a vertical CCD charge transfer unit 3 that is a region for electrically transferring signal charges, a channel stop region 4 that is an element isolation region for each pixel, and a light receiving unit for each pixel. A photodiode portion 5 and a charge read region 6 for reading signal charges generated in the photodiode portion 5 to the vertical CCD charge transfer portion 3 are formed.

  The gate electrode 8 is formed on the substrate via the gate insulating film 7. In this case, the transfer gate electrode 8 is used for both charge transfer and signal charge reading. A first insulating film 9 or a third insulating film 11 made of a silicon oxide film is formed on the upper surface and the side wall of the gate electrode 8, and at least via a fourth insulating film 12 made of a silicon nitride film, for example A light shielding film 13 such as a tungsten (W) film is provided. Since the third insulating film 11 formed with a uniform film thickness by thermal oxidation is provided on the surface of the light receiving portion 5, the photodiode surface P + implantation is performed with little variation, so that deterioration of read characteristics is suppressed. it can.

  Therefore, in the solid-state imaging device 20 according to the first embodiment, the gate is formed of the gate insulating film 7 on the substrate surface, the conductive film (gate electrode material 8a) having the gap G in the vertical transfer portion and the opening in the light receiving portion 5. The electrode 8 is formed, and the gap G has at least a region in which the conductive film is not eroded by thermal oxidation as in the prior art. In the gap G, a fourth insulating film 12 (silicon nitride film) is buried from the substrate surface side through the gate insulating film 7 and the first insulating film 9 (silicon oxide film). On the other hand, a fourth insulating film 12 is formed on the surface side of the light receiving portion 5 via a third insulating film 11 (thermal oxide film) having a stable film thickness. The insulating film 9 is a CVD oxide film, and the third insulating film 11 thereon is a thermal oxide film. According to the solid-state imaging device 20 according to the present invention described above, the gap G between the charge transfer electrodes does not expand due to thermal oxidation of the conductive film as in the conventional case, and the surface of the transfer channel below the gap G also has the first insulation. Since the film 9 is not oxidized, there is no deterioration in charge transfer. Further, on the surface side of the light receiving portion 5, an insulating film having a uniform thickness is formed by the third insulating film 11 which is a thermal oxide film, so that impurity ion implantation of the photodiode surface P + is performed with little variation. Deterioration of read characteristics can be suppressed. Further, since the buried insulating film of the gap G and the antireflection film on the light receiving portion 5 are formed simultaneously by the fourth insulating film 12 of the silicon nitride film, an interlayer film is formed on the gate electrode 8 more than necessary. As a result, the surface height of the light shielding film 13 does not become higher, so that it is possible to suppress the deterioration of the light receiving sensitivity with respect to the oblique light.

  A method for manufacturing the solid-state imaging device 20 of the first embodiment having the above-described configuration will be described in detail with reference to FIGS.

  3 to 10 are longitudinal sectional views showing respective manufacturing steps in the method for manufacturing the solid-state imaging device 20 of FIG. 1, and FIGS. 3A to 10A are taken along line AA ′ of FIG. FIG. 3B to FIG. 10B are longitudinal sectional views taken along the line BB ′ of FIG.

  As shown in the impurity diffusion region forming step in FIG. 3A and FIG. 3B, first, a p-type well 2 is formed in an n-type semiconductor substrate 1 made of, for example, n-type silicon, As each impurity diffusion region, an n-type impurity is introduced and a photodiode portion 5 and a vertical CCD charge transfer portion 3 are selectively introduced. A p-type impurity is selectively introduced and a channel stop pixel separation portion 4 is vertically directed. A charge reading region 6 for reading to the charge transfer unit 3 is formed.

  Further, in the gate insulating film and gate electrode material film forming step, on the surface of the semiconductor substrate 1 on which each impurity diffusion region is formed, a gate insulating film 7 made of, for example, a 30 nm-thickness silicon oxide film, For example, a gate electrode material film 8a made of phosphorus-doped polysilicon having a thickness of 200 nm is formed.

  Next, as shown in the gate electrode formation step in FIGS. 4A and 4B, the remaining film of the gate insulating film 7 is, for example, about 10 nm using a photoresist (not shown) as a mask. Then, the gate electrode material film 8a is dry-etched to form a gate electrode 8 having a gap G having a space width of, for example, 100 nm and an opening 8b above the light receiving portion 5.

Thereafter, as shown in the steps of forming the silicon oxide film (first insulating film) and the silicon nitride film (second insulating film) in FIGS. 5A and 5B, the gate insulating film 7 and the gate electrode A first insulating film 9 made of a silicon oxide film (HTO) having a thickness of 20 nm, for example, is formed at a temperature of 800 degrees Celsius on the entire surface of the substrate 8 using LPH or the like using SiH ₄ gas and N ₂ O. Film. Subsequently, a second insulation made of a silicon nitride film having a thickness of 70 nm, for example, at a temperature of 800 degrees Celsius is formed on the first insulation film 9 by using an LPH method or the like using SiH ₂ CL ₂ gas and NH ₃ gas. A film 10 (sacrificial film) is formed. In this case, the film thickness is appropriately set so that the gap G is completely filled with the first insulating film 9 and the second insulating film 10 thereon.

  As described above, the first insulating film 9 and the second insulating film 10 formed thereon are separately formed because the second electrode made of silicon nitride film is formed on the gate electrode material film 8a made of phosphorus-doped polysilicon. Therefore, the second insulating film 10 is formed in the polysilicon gap G through the first insulating film 9 having good adhesion to the polysilicon.

  Subsequently, as shown in the silicon nitride film (second insulating film) etch back step in FIGS. 6A and 6B, the silicon nitride film of the second insulating film 10 is replaced with the first insulating film 9. The entire surface is etched back until the silicon oxide film is exposed to remove the silicon nitride film of the second insulating film 10 above the surface of the light receiving portion 5 while leaving the second insulating film 10 in the gap G remaining. Then, the second insulating film 10 is formed as a sidewall on the side wall of the gate electrode 8. Note that this entire surface etch back may be performed until the first insulating film 9 on the gate electrode 8 is completely removed. However, for example, when the etching amount is too large, the first insulating film 9 and the second insulating film 10 filled in the gap G recede and function as an oxidation suppression film in the thermal oxidation performed later. Therefore, it may be adjusted as appropriate so that the gap G is protected by the second insulating film 10 after the entire surface is etched back.

  Further, as shown in the silicon oxide film (first insulating film) and gate insulating film etching removal step in FIGS. 7A and 7B, the first insulating film 9 above the surface of the light receiving portion 5 and Then, the gate insulating film 7 is removed by etching using, for example, hydrofluoric acid (HF) so that the silicon substrate is exposed.

  The wet etching at this time is adjusted so that the second insulating film 10 on the side wall of the gate electrode 8 is not lifted off. In the overall etch back process shown in FIGS. 6A and 6B, this wet etching can be minimized as much as possible by thinning the remaining film after etching the gate insulating film 7 to 10 nm or less. In addition, the horizontal penetration of the first insulating film 7 below the end of the gate electrode 8 can be reduced.

  Thereafter, as shown in the silicon thermal oxide film (third insulating film) formation step in FIGS. 8A and 8B, for example, thermal oxidation at 850 degrees Celsius is performed, and the surface of the light receiving unit 5 and the gate A silicon oxide film as a third insulating film 11 is formed with a thickness of 10 nm on the surface of the electrode 8. A step is formed on the silicon surface of the n-type semiconductor substrate 1 above the light receiving portion 5 by the thermal oxide film as the third insulating film 11. Since the third insulating film 11 on the surface of the light receiving portion 5 is formed with a uniform film thickness by thermal oxidation, the photodiode surface P + implantation is performed with little variation when performed after this (not shown). Deterioration of characteristics can be suppressed.

  In this case, even if thermal oxidation is performed, the gap G is protected by the second insulating film 10 functioning as an oxidation suppression film, so that the oxidation shift is 0. The expansion of the space width of the electrode 8 can be suppressed.

Subsequently, as shown in the photodiode surface P + implantation and the second insulating film removal step in the gap G in FIGS. 9A and 9B, the photodiode is passed through the third insulating film 11 which is a silicon thermal oxide film. The surface P + implantation is stably performed to form a surface P + layer (not shown), and the second insulating film 10 in the gap G is completely etched away using phosphoric acid (H ₃ PO ₄ ). Since the gate electrode 8 is covered with the first insulating film 9 or the third insulating film 11 formed of a silicon oxide film having a high selectivity with respect to the second insulating film 10 of phosphoric acid, the gate electrode The surface of the polysilicon as 8 is not roughened and does not cause a resistance abnormality.

  Further, as shown in the silicon nitride film (fourth insulating film) forming step in FIGS. 10A and 10B, a silicon nitride film having a thickness of, for example, 50 nm is formed as the fourth insulating film 12. Thus, the filling of the interlayer insulating film into the gap G and the formation of the antireflection film above the surface of the light receiving portion 5 are simultaneously performed.

The second insulating film 10 made of silicon nitride is removed from the gap G with phosphoric acid (H ₃ PO ₄ ), and the fourth insulating film 12 made of the same silicon nitride film is filled back into the gap G. For this reason, the second insulating film 10 on the side wall of the gate electrode 8 is also removed, and the width of the insulating film on the side wall of the gate electrode 8 can be minimized. In addition, since an interlayer film is not formed more than necessary on the gate electrode 8 and the surface height of the light shielding film 13 is not increased as in the prior art, it is possible to suppress deterioration of light receiving sensitivity to oblique light. can do.

  Through the above steps, it is possible to form both a uniform insulating film on the surface of the light-receiving portion 5 and an ideal shape of the interlayer insulating film in which the gap G is not widened.

  Thereafter, in the light shielding film forming step, a light shielding film 13 such as a tungsten (W) film having a thickness of 100 nm is formed on the entire surface of the substrate by, for example, CVD, and the light shielding film 10 corresponding to the photodiode 5 is opened. The solid-state imaging device 20 shown in FIGS. 2A and 2B is obtained. Although not shown, for example, a silicon oxide film having a thickness of 50 nm is formed between the light shielding film 13 and the light shielding film 13 on the fourth insulating film 12 for the purpose of ensuring the breakdown voltage between the light shielding film 13 and the gate electrode 8 and the semiconductor substrate 1. A titanium nitride film may be formed for the purpose of forming or improving adhesion.

  Thereafter, although not shown, a passivation film such as silicon nitride is formed by a plasma CVD method or the like, and a color filter and an on-chip lens or the like are further formed thereon, whereby the solid-state imaging device 20 can be obtained.

  Therefore, in the manufacturing method of the solid-state imaging device 20 according to the first embodiment, n-type impurities are injected into the p-type well of the semiconductor substrate 1 which is an n-type silicon substrate, and the light receiving unit 5 and the signal from the light receiving unit 5 Impurity diffusion region forming step for forming a vertical CCD charge transfer unit 3 for transferring charges, and an n-type semiconductor substrate 1 on which the light receiving unit 5 and the vertical CCD charge transfer unit 3 are formed as impurity diffusion regions The gate electrode material film 8a as a conductive film formed through the gate insulating film 7 is patterned to form gaps G (gap parts) at equal intervals in the vertical CCD charge transfer part 3 and image the incident light. A charge transfer electrode forming step of forming a gate electrode 8 having an opening 8b formed above each of the plurality of light receiving portions 5, and a first insulating film 9 formed on the gate electrode 8 and the gate insulating film 7. A first insulating film forming step for forming the first insulating film 9 also in the gap G, and a second insulating film 10 as a sacrificial film are formed on the first insulating film 9, and the gap Until the substrate surface above the light receiving portion 5 is exposed in the state in which the second insulating film 10 is embedded in the G and the second insulating film 10 in the gap G is left. The second insulating film 10, the first insulating film 9, and the gate insulating film above the light receiving portion 5 are removed, and the second surface on the gate electrode 8 is exposed until the upper surface (upper surface) of the gate electrode 8 is exposed. Etchback process for removing the insulating film 10 and the first insulating film 9, and a third insulating film whose thickness is stabilized thinly by thermal oxidation on the substrate surface above the light receiving portion 5 and the upper surface of the gate electrode 8 11 is formed on the surface side of the light receiving portion 5 (base) through the third insulating film 11. The surface p + layer is formed on the light receiving portion 5 by injecting a p-type impurity having a conductivity type opposite to the impurity conductivity type (n-type) of the light receiving portion 5 into the light receiving portion 5. A fourth insulating film forming step of forming a fourth insulating film 12 over the entire surface of the substrate and refilling the insulating film after removing the second insulating film 10 in the gap G; A light-shielding film 13 is formed on the insulating film 12, and the light-shielding film 13 above the light-receiving portion 5 includes a light-shielding film forming step of opening an opening for light incidence.

  In this case, during the thermal oxidation process, the gap G between the charge transfer electrodes is filled with a silicon nitride film as a thermal oxidation suppressing film. Further, the gap G between the charge transfer electrodes and the opening 8b above the light receiving portion 5 which is a photoelectric conversion portion are formed simultaneously. Further, the surface of the light receiving portion 5 is thermally oxidized to form a thin and stable third insulating film 11, and the n-type semiconductor substrate 1 receives light through the thin and stable third insulating film 11. A p-type impurity ion is implanted into the surface portion of the portion 5 to form a high concentration surface p + layer. Further, the second insulating film 10 is removed from the gap G, and the fourth insulating film 12 is backfilled in the gap G. In addition, the buried insulating film (fourth insulating film 12) in the gap G between the charge transfer electrodes and the antireflection film (fourth insulating film 12) on the light receiving portion 5 are manufactured using the same material in the same process.

  As described above, according to the method for manufacturing the solid-state imaging device 20 of Embodiment 1, the silicon nitride film as the thermal oxidation suppressing film is filled in the gap G between the charge transfer electrodes during the thermal oxidation process. The surface of the transfer channel under the gap G and the side wall of the gate electrode 8 are not oxidized, and expansion of the charge transfer interelectrode gap G due to thermal oxidation as in the related art can be suppressed. As described above, since there is no deterioration of the signal charge reading characteristics and the light receiving sensitivity in the light receiving section 5 and the expansion of the gap G between charge transfers in the thermal oxidation process can be suppressed, a fine and solid that can transfer charges at high speed. The image sensor 20 can be manufactured.

  Further, since the gap G between the charge transfer electrodes and the opening 8b above the light receiving portion 5 which is a photoelectric conversion portion are formed at the same time, the gap G between the charge transfer electrodes and the opening 8b above the light receiving portion 5 are conventionally formed. The alignment accuracy does not vary, and pixel characteristics are not deteriorated.

  Further, the surface of the light receiving portion 5 is thermally oxidized to form a thin and stable third insulating film 11, and the n-type semiconductor substrate 1 receives light through the thin and stable third insulating film 11. Since the p-type impurity ions are implanted into the surface portion of the portion 5 to form a high-concentration surface p + layer, the p-type impurity ion implantation depth and its concentration do not fluctuate or vary. Degradation does not occur.

  Furthermore, since the second insulating film 10 is removed from the gap G and the fourth insulating film 12 is backfilled in the gap G, the second insulating film 10 on the side wall of the gate electrode 8 is also removed, The insulating film width on the side wall of the gate electrode 8 can be minimized. In addition, the buried insulating film (fourth insulating film 12) in the gap G between the charge transfer electrodes and the antireflection film (fourth insulating film 12) on the light receiving portion 5 are manufactured with the same material in the same process. The interlayer film (only the third insulating film 11 and the fourth insulating film 12 here) is not formed on the gate electrode 8 more than necessary, and the surface height of the light shielding film 13 is not increased.

  Accordingly, an insulating film (here, only the first insulating film 9 and the fourth insulating film 12) can be formed in the gap G between the gate electrodes 8 without deterioration of the pixel characteristics.

(Embodiment 2)
FIG. 11 shows, as Embodiment 2 of the present invention, an electronic device using a solid-state imaging device that obtains a color image signal by performing predetermined signal processing on an imaging signal from the solid-state imaging device 20 according to Embodiment 1 of the present invention. It is a block diagram which shows the schematic structural example of an information apparatus.

  In FIG. 6, the electronic information device 90 of the third embodiment includes a solid-state imaging device 91 that obtains a color image signal by performing predetermined signal processing on the imaging signal from the solid-state imaging device 20 of the first embodiment, and the solid-state imaging. A memory unit 92 such as a recording medium that enables data recording after the color image signal from the device 91 is subjected to predetermined signal processing for recording, and the color image signal from the solid-state imaging device 91 is subjected to predetermined signal processing for display A display unit 93 such as a liquid crystal display device that can be displayed on a display screen such as a liquid crystal display screen later, and a color image signal from the solid-state imaging device 91 are subjected to predetermined signal processing for communication, and then communication processing is enabled. An image of a communication unit 94, such as a transmission / reception device, and a printer or the like that can perform print processing after performing predetermined print signal processing for color image signals from the solid-state imaging device 91 for printing. And a power unit 95. The electronic information device 90 is not limited to this, but in addition to the solid-state imaging device 91, at least one of a memory unit 92, a display unit 93, a communication unit 94, and an image output unit 95 such as a printer. You may have.

  As described above, the electronic information device 90 includes, for example, a digital camera such as a digital video camera and a digital still camera, an in-vehicle camera such as a surveillance camera, a door phone camera, and an in-vehicle rear surveillance camera, and a video phone camera. An electronic device having an image input device such as an image input camera, a scanner device, a facsimile device, a camera-equipped mobile phone device, and a portable terminal device (PDA) is conceivable.

  Therefore, according to the third embodiment, based on the color image signal from the solid-state imaging device 91, it can be displayed on the display screen, or can be printed out on the paper by the image output unit 95. (Printing), communicating this as communication data in a wired or wireless manner, performing a predetermined data compression process in the memory unit 92 and storing it in a good manner, or performing various data processings satisfactorily Can do.

  Although not described in detail in the first embodiment, the conductive film formed on the semiconductor substrate via the gate insulating film is patterned to form a gap portion on the charge transfer portion, and A charge transfer electrode forming step for forming charge transfer electrodes each having an opening formed above a plurality of light receiving portions for imaging incident light, and a first insulation on the charge transfer electrode and the gate insulating film including the gap portion A first insulating film forming step for forming a film; a second insulating film forming step for forming a second insulating film on the first insulating film; and a second insulating film in the gap portion. In the state of being left behind, the etch back process of removing each insulating film until the upper surface of the substrate and the charge transfer electrode above the light receiving portion is exposed, and the upper surface of the substrate and the upper surface of the charge transfer electrode above the light receiving portion. A third insulating film is formed by thermal oxidation to form a third insulating film. If there is a film forming step and a fourth insulating film forming step for forming a fourth insulating film on the entire surface of the substrate after removing the second insulating film in the gap, charge transfer failure and light reception It is possible to achieve the object of the present invention in which an insulating film can be formed in the gap between the transfer electrodes without deterioration of various pixel characteristics such as reduction of the area and deterioration of light receiving sensitivity.

  As mentioned above, although this invention was illustrated using preferable Embodiment 1, 2 of this invention, this invention should not be limited and limited to this Embodiment 1,2. It is understood that the scope of the present invention should be construed only by the claims. It is understood that those skilled in the art can implement an equivalent range based on the description of the present invention and the common general technical knowledge, from the description of specific preferred embodiments 1 and 2 of the present invention. Patents, patent applications, and documents cited herein should be incorporated by reference in their entirety, as if the contents themselves were specifically described herein. Understood.

  The present invention relates to a solid-state imaging device composed of a semiconductor element that images image light from a subject by photoelectric conversion, and a method for manufacturing the solid-state imaging device. Regarding a solid-state imaging device manufactured by a manufacturing method, for example, a digital camera such as a digital video camera and a digital still camera using the solid-state imaging device as an image input device in an imaging unit, an image input camera such as a surveillance camera, a scanner device, In the field of electronic information equipment such as a facsimile apparatus, a television telephone apparatus, and a camera-equipped mobile telephone apparatus, when a third insulating film to be thermally oxidized is formed, a second film serving as a thermal oxidation suppressing film is formed in the gap between the charge transfer electrodes. Since the insulating film is filled, the transfer channel surface under the gap and the side wall of the charge transfer electrode are not oxidized, It is possible to suppress the expansion by conventional such thermal oxidation of the gap between the charge transferring electrodes, no deterioration of the pixel characteristic, such as reduction of the charge transfer failure and the light-receiving region. In addition, since the gap between the charge transfer electrodes and the opening above the photoelectric conversion unit are formed at the same time, the alignment accuracy between the gap between the charge transfer electrodes and the opening above the photoelectric conversion unit does not vary as in the past, As a result, pixel characteristics such as charge transfer failure are not deteriorated. Furthermore, the surface of the light receiving portion is thermally oxidized to form a thin and stable third insulating film, and this thin and stable third insulating film is passed through the semiconductor substrate into the semiconductor substrate opposite to the light receiving portion. Since the conductivity type impurity ions are implanted, the implantation depth and concentration of the impurity ions do not fluctuate or vary, and pixel characteristics such as light receiving sensitivity are not deteriorated. Further, since the second insulating film is removed from the gap and the fourth insulating film is backfilled in the gap, the second insulating film on the side wall of the charge transfer electrode is also removed, and the insulating film on the side wall of the gate electrode is removed. The width can be minimized. Also, if the insulating film embedded in the gap portion between the charge transfer electrodes and the antireflection film on the light receiving portion are made of the same material in the same process, an interlayer film is not formed more than necessary on the charge transfer electrode, The height of the surface of the light-shielding film is not increased as in the prior art, and the problem that sensitivity is deteriorated due to the fact that, for example, oblique condensing cannot be performed is eliminated. Therefore, there is no deterioration of various pixel characteristics such as charge transfer failure, reduction of the light receiving area, and deterioration of light receiving sensitivity, and the insulating film can be stably formed in the gap between the transfer electrodes.

1 n-type semiconductor substrate (semiconductor substrate)
2 p-type well 3 vertical CCD charge transfer unit (charge transfer unit)
4 Channel stop area (pixel separation area)
5 Light receiver (photodiode or photoelectric converter)
6 Charge readout region 7 Gate insulating film 8 Gate electrode (charge transfer electrode)
8a Gate electrode material film (conductive film)
8b Opening 9 First insulating film (CVD silicon oxide film)
10 Second insulating film (silicon nitride film)
11 Third insulating film (silicon thermal oxide film)
12 Fourth insulating film (silicon nitride film)
13 Shading film (tungsten film)
G gap (gap part)
DESCRIPTION OF SYMBOLS 20 Solid-state image sensor 90 Electronic information equipment 91 Solid-state imaging device 92 Memory part 93 Display part 94 Communication part 95 Image output part

Claims (16)

  A conductive film formed on a semiconductor substrate through a gate insulating film is patterned to form a gap portion on the charge transfer portion, and an opening is formed above each of the plurality of light receiving portions that capture incident light. A charge transfer electrode forming step of forming the charge transfer electrode, a first insulating film forming step of forming a first insulating film on the charge transfer electrode and on the gate insulating film including the gap portion, A second insulating film forming step for forming a second insulating film on the first insulating film, and a substrate surface above the light receiving portion in a state in which the second insulating film in the gap is left. And an etch back step of removing each insulating film until the upper surface of the charge transfer electrode is exposed, and forming a third insulating film on the substrate surface above the light receiving portion and the upper surface of the charge transfer electrode by thermal oxidation. A third insulating film forming step for forming a film, and a second insulating film in the gap portion. After removing the film, a method for manufacturing a solid-state imaging device and a fourth insulating film forming step of forming a fourth insulating film on the entire surface of the substrate. 2. The first insulating film forming step forms a silicon oxide film having a predetermined film thickness as the first insulating film at a predetermined temperature using SiH ₄ gas and N ₂ O by LPCVD. The manufacturing method of the solid-state image sensor as described in 1 .. In the second insulating film forming step, a silicon nitride film having a predetermined film thickness is formed as the second insulating film at a predetermined temperature using SiH ₂ CL ₂ gas and NH ₃ gas by LPCVD. Item 2. A method for manufacturing a solid-state imaging device according to Item 1.   In the etch-back step, the second insulating film is etched back until the first insulating film is exposed, and the second insulation on the surface side of the light receiving portion and the surface side of the charge transfer electrode is performed. A second insulating film removing step of leaving the second insulating film in the gap portion while removing the film, and the first insulating film and the gate insulation until the substrate surface above the surface of the light receiving portion is exposed. The method for manufacturing a solid-state imaging device according to claim 1, further comprising a first insulating film removing step of removing the first insulating film until the upper surface of the charge transfer electrode is exposed while removing the film.   A surface reverse conductivity type layer forming step of forming a surface reverse conductivity type layer by ion-implanting an impurity having a conductivity type opposite to the impurity conductivity type of the light receiving portion into the surface side of the light receiving portion through the third insulating film; Furthermore, the manufacturing method of the solid-state image sensor of Claim 1 which has. 2. The method of manufacturing a solid-state imaging device according to claim 1, wherein the second insulating film in the gap portion is removed by etching using phosphoric acid (H ₃ PO ₄ ) before forming the fourth insulating film.   The fourth insulating film forming step simultaneously fills the gap portion with the fourth insulating film and forms the fourth insulating film as an antireflection film above the surface of the light receiving portion. Item 2. A method for manufacturing a solid-state imaging device according to Item 1.   Prior to the charge transfer electrode forming step, a predetermined impurity is ion-implanted into the semiconductor substrate to form the light receiving portion and a charge transfer portion for transferring a signal charge from the light receiving portion, respectively. The method for manufacturing a solid-state imaging device according to claim 1, further comprising a diffusion region forming step.   The light-shielding film forming step of forming a light-shielding film on the fourth insulating film and opening a light-shielding film above the light-receiving portion after the fourth insulating film-forming step. Manufacturing method of solid-state image sensor.   The method for manufacturing a solid-state imaging element according to claim 1, wherein both the second insulating film and the fourth insulating film are silicon nitride films.   The method for manufacturing a solid-state imaging element according to claim 1, wherein the first insulating film is a CVD oxide film, and the third insulating film is a thermal oxide film.   The method for manufacturing a solid-state imaging device according to claim 1, wherein the gap portion is a gap between charge transfer electrodes. A solid-state imaging device manufactured by the method for manufacturing a solid-state imaging device according to claim 1,
A charge transfer electrode made of a conductive film having an opening above the light receiving part and the gap part at a predetermined interval on the charge transfer part is provided on the semiconductor substrate via the gate insulating film. The conductive film is not eroded by thermal oxidation, and the first insulating film and the fourth insulating film are embedded in the gap portion from the substrate surface through the gate insulating film, and above the light receiving portion. A solid-state imaging device in which the fourth insulating film is formed on the surface of the substrate via the third insulating film.   The solid-state imaging device according to claim 13, wherein a step is formed on a surface of the semiconductor substrate by a thermal oxide film that is the third insulating film.   14. The solid according to claim 13, wherein a buried insulating film in a gap portion between the charge transfer electrodes is constituted by the fourth insulating film, and the fourth insulating film also serves as an antireflection film on the light receiving portion. Image sensor.   An electronic information device using the solid-state imaging device according to claim 13 as an image input device in an imaging unit.

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