JP5231288B2 - Semiconductor device manufacturing method, solid-state image sensor manufacturing method, solid-state image sensor, and electronic information device - Google Patents

Description

  The present invention relates to a method for forming a resist pattern used in a photolithography process, a method for manufacturing a semiconductor device using the resist pattern, and a method for manufacturing the semiconductor device, including, for example, a semiconductor element that photoelectrically converts image light from a subject and images it Manufacturing method of the solid-state imaging device, a solid-state imaging device manufactured by the manufacturing method of the solid-state imaging device, and a digital 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 The present invention relates to an electronic information device such as a camera, an image input camera such as a surveillance camera, a scanner device, a facsimile device, a television telephone device, and a camera-equipped mobile phone device.

  A case where a resist pattern forming method in a lithography process in a conventional method for manufacturing a semiconductor device is applied to a method for manufacturing a solid-state imaging device will be described.

  FIG. 9A to FIG. 9D are main part longitudinal cross-sectional views showing a first gate electrode forming step for explaining a method of manufacturing a solid-state imaging device using a conventional resist pattern forming method. 10 (a) to 10 (c) show the steps up to the second gate electrode forming step for explaining the manufacturing method of the solid-state imaging device using the conventional resist pattern forming method following FIG. 9 (d). 11 (a) to 11 (c) are nitride film formations for explaining a method of manufacturing a solid-state imaging device using a conventional resist pattern forming method following FIG. 10 (c). FIG. 12A to FIG. 12C are diagrams for explaining a method for manufacturing a solid-state imaging device using a conventional resist pattern forming method subsequent to FIG. 11C. It is a principal part longitudinal cross-sectional view which shows to the nitride film formation process of this.

First, as shown in FIG. 9A, a gate oxide film 102 which is a SiO ₂ film is formed on a silicon substrate 101 as a semiconductor substrate, and a gate nitride film 103 is further formed on the gate oxide film 102. A gate HTO film 104 is formed on the gate nitride film 103, and a first polysilicon film 105 is further formed on the gate HTO film 104. Since this first polysilicon film 105 becomes the first gate electrode, it is doped to have conductivity.

  Further, as shown in FIG. 9B, a photoresist pattern 106 serving as a mask for processing the first gate electrode is formed on the doped first polysilicon film 105. That is, a photoresist film material is formed on the first polysilicon film 105, and exposed and developed so that the photoresist film remains at a position on the first polysilicon film 105 where the first gate electrode is formed. By patterning into a shape, a photoresist pattern 106 for processing the first gate electrode is formed on the first polysilicon film 105.

  Subsequently, as shown in FIG. 9C, the pre-doped first polysilicon film 105 is etched by using the photoresist pattern 106 on the first polysilicon film 105 as a mask, and each of the first polysilicon film 105 is in a predetermined position. A gate electrode 105A is formed.

  In this manner, the first gate electrode 105A can be formed on the gate HTO film 104 by the steps of FIGS. 9A to 9C. At this time, the first gate electrode 105A can be doped with impurity ions in a self-aligned manner, and an impurity diffusion region of the photodiode PD can be formed on the surface side of the silicon substrate 101 between the adjacent first gate electrodes 105A.

  Thereafter, as shown in FIG. 9D, the first gate electrode 105A formed in a predetermined shape from the pre-doped first polysilicon film 105 is subjected to surface thermal oxidation so that the upper surface and side surfaces of the first gate electrode 105A are obtained. A first interlayer insulating film 107 is formed to cover the substrate.

  Next, as shown in FIG. 10A, a second polysilicon film 108 is formed on the first interlayer insulating film 107 and the gate HTO film 104, and the formed second polysilicon film 108 is a second gate. Since it becomes an electrode, it is doped to provide conductivity.

  Subsequently, as shown in FIG. 10B, a photoresist pattern 109 is formed on the doped second polysilicon film 108 for processing the second gate electrode. That is, a photoresist film is formed on the second polysilicon film 108, and exposed and developed so that the photoresist film remains above the first gate electrode 105A where the second gate electrode is formed. By patterning, a photoresist pattern 109 is formed on the second polysilicon film 108.

  Thereafter, as shown in FIG. 10C, the pre-doped second polysilicon film 108 is etched using the photoresist pattern 109 on the second polysilicon film 108 as a mask, and the gate HTO film 104 is gated. The nitride film 103 is further etched away to the middle of the gate oxide film 102 to form second gate electrodes 108A at predetermined positions on the first interlayer insulating film 107 corresponding to the positions of the first gate electrodes 105A.

  In this manner, the second gate electrode 108A can be formed on the first interlayer insulating film 107 by the steps of FIGS. 10A to 10C. Thus, in order to match the peripheral height of the phototransistor PD, a two-stage first gate electrode 105A and second gate electrode 108A are formed.

  Next, as shown in FIG. 11A, after removing the photoresist pattern 109 remaining on the second gate electrode 108A, as shown in FIG. 11B, a pre-doped second polysilicon film is formed. The second gate electrode 108A formed in an island shape from the surface 108 is thermally oxidized to form the second interlayer insulating film 110 that covers the upper surface and the side surface of the second gate electrode 108A, and the remaining gate oxidation between the gate electrodes The film 102 is also thermally oxidized to form the second interlayer insulating film 110.

  Subsequently, as shown in FIG. 11C, a nitride film 111 of a SiN film is formed to a predetermined thickness on the entire surface of the substrate on the second interlayer insulating film 110.

  Next, as shown in FIG. 12A, a photoresist pattern 112 is formed on the central region of the nitride film 111 between the gate electrodes for the shape processing of the nitride film 111. That is, a photoresist film material is formed on the nitride film 111, and is exposed and developed into a predetermined shape so that the photoresist film remains in the central region between the gate electrodes and above the central region of the photodiode PD. By patterning, a photoresist pattern 112 for nitride film processing is formed on the nitride film 111. At this time, constriction B (halation) occurs on the side surface of the photoresist film 112 in response to exposure reflected light from the nitride film 111 and the polysilicon film.

  Subsequently, as shown in FIG. 12B, the nitride film 111 and the second interlayer insulating film 110 are dry-etched using the photoresist pattern 112 on the nitride film 111 in the central region between the gate electrodes as a mask. The nitride film 111 is further etched away to the middle of the second interlayer insulating film 110 to leave a predetermined thickness as the second interlayer insulating film 110A, and is a central region between the gate electrodes, above the central region of the photodiode PD. An island-shaped nitride film 111A having a tapered corner is formed. Thus, the line width control of the island-shaped nitride film 111A is deteriorated.

  Further, as shown in FIG. 12C, the photoresist pattern 112 remaining on the nitride film 111A having a predetermined shape is peeled off and removed.

JP-A-6-20943

  In recent years, with the high integration and miniaturization of LSI, the demand for dimensional accuracy has become strict.

  In the above-described conventional configuration, when a film serving as a reflective film is formed on a semiconductor substrate having a stepped portion, the multiple interference effect due to the resist film thickness variation and the stepped side surface as shown in FIG. Constriction B (halation) tends to occur on the side surface of the photoresist film 112 due to the reflected light A of ultraviolet rays. Thus, when the constriction B (halation) occurs on the side surface of the photoresist film 112, the dimensional accuracy of the line width control of the nitride film 111A by the subsequent etching is adversely affected. There is a possibility that the light receiving efficiency in the photodiode PD of the solid-state imaging device is deteriorated due to the deterioration of the line width dimensional accuracy of the nitride film 111A that acts as an antireflection film in the visible light region. The nitride film 111A is an organic antireflection film and is an antireflection film in the visible light region. However, since the ultraviolet rays at the time of ultraviolet exposure are reflected, the side surface of the photoresist film 112 is constricted B. (Halation) will occur.

  In order to reduce the influence of reflection from such a stepped portion, an antireflection film method of applying a photoresist film after forming an antireflection film that absorbs exposure light on a reflective substrate is used after a resist pattern is formed. Problems arise when removing the antireflection film. This resist pattern forming method is described in FIGS. 13A and 13B of Patent Document 1. FIG.

  FIG. 13A and FIG. 13B are longitudinal sectional views of main parts for explaining the problems of the conventional resist pattern forming method described in Patent Document 1. FIG.

  First, as shown in FIG. 13A, after forming a gate oxide film 202 on the surface of a silicon substrate 201, a polysilicon film 203 is deposited on the entire surface of the substrate, and particularly ultraviolet rays are absorbed on the polysilicon film 203. A possible antireflection film material is formed. Further, a positive resist film is applied to the entire surface of the formed antireflection film material.

  Further, a positive resist pattern 205 is obtained by exposure and development. Subsequently, when the antireflection film material in a region other than the region immediately below the positive resist pattern 205 is removed by wet etching, an antireflection film 204 having an undercut state is formed or a tapered scum is formed. Occurs and the dimensional accuracy deteriorates significantly.

  On the other hand, as shown in FIG. 13B, when the removal of the antireflection film material in the above-described unnecessary area is performed by dry (plasma) etching processing in order to improve the dimensional accuracy, the antireflection film 204A that remains is formed. Although there is no undercut, the positive resist pattern 205 is deformed into a positive resist pattern 205A. This is because the dry etching process is anisotropic plasma etching mainly composed of oxygen, so that the upper part of the positive resist film is also etched away, resulting in a corner drop. In the positive resist film 205A having such a shape, there is a possibility that the dimensions of the positive resist film 205A may fluctuate during the subsequent dry etching of the underlying polysilicon film 203. In particular, this phenomenon becomes a serious problem when the resist film is thinned to improve the resolution and the depth of focus.

  In any case, in the case of FIG. 13B, the target for dry (plasma) etching using the positive resist pattern 205A as a mask is the polysilicon film 203 under the antireflection film, and the remaining antireflection film 204A is formed. Since it is buried under the positive resist pattern 205A, the antireflection film 204A must be separately removed by etching in a separate process.

  The present invention solves the above-described conventional problems, and it is not necessary to provide a separate process, and the film pattern immediately below the resist pattern can be formed as a film pattern having the same shape as the resist pattern with high dimensional accuracy. Resist pattern forming method, semiconductor device manufacturing method using the same, solid-state image sensor manufacturing method as the semiconductor device, solid-state image sensor manufactured by the solid-state image sensor manufacturing method, and solid-state image sensor An object of the present invention is to provide an electronic information device such as a camera-equipped mobile phone device used as an image input device in an imaging unit.

  According to the method of forming a resist pattern of the present invention, a second antireflection film is formed on the entire surface of a semiconductor substrate on which a semiconductor device is formed to prevent exposure from being reflected and to dissolve in a developer. A resist pattern having a shape is formed, whereby the above object is achieved.

  Preferably, in the resist pattern forming method of the present invention, a first antireflection film forming step of forming a first antireflection film for preventing reflection of visible light on the entire surface of the semiconductor substrate on which the semiconductor device is formed; A second antireflection film forming step of forming the second antireflection film on the first antireflection film, and a central region of a predetermined surface region of the semiconductor substrate adjacent to the gate electrode constituting the semiconductor device And a photoresist pattern forming step of forming a photoresist pattern for shape processing of the first antireflection film.

  Further preferably, in the photoresist pattern forming step in the resist pattern forming method of the present invention, exposure is absorbed by the second antireflection film to suppress the reflected light of the exposure, and the side surface of the photoresist film by the reflected light is suppressed. Prevent constriction.

  Further preferably, in the photoresist pattern forming step in the resist pattern forming method of the present invention, the second antireflection film other than just under the photoresist pattern is dissolved and removed by a developer.

  Further preferably, in the method for forming a resist pattern of the present invention, the first antireflection film is an organic film, and the second antireflection film is an inorganic film.

  Further preferably, the exposure in the method for forming a resist pattern of the present invention is ultraviolet light.

  According to another aspect of the present invention, there is provided a method for manufacturing a semiconductor device, comprising: etching the first antireflection film for preventing visible light reflection using the photoresist pattern formed by the resist pattern forming method of the present invention as a mask; Having a first antireflection film forming step of forming an island-shaped first antireflection film in which the edge portion is formed in a square shape without being tapered in a central region of a predetermined surface region of a semiconductor substrate adjacent to Thus, the above object is achieved.

  Preferably, the second antireflection film in the method for manufacturing a semiconductor device of the present invention is made of a material that is soluble in the photoresist pattern stripper in addition to the photoresist pattern developer.

  Further preferably, in the method of manufacturing a semiconductor device according to the present invention, the first antireflection film forming step may be performed when the photoresist pattern on the second antireflection film is peeled and removed after the etching process. The second antireflection film directly under the resist pattern is also dissolved and removed.

  Further preferably, in the method for manufacturing a semiconductor device of the present invention, a first gate electrode forming step of forming a first gate electrode constituting the semiconductor device on a gate oxide film formed on a semiconductor substrate; A first interlayer insulating film forming step of forming a first interlayer insulating film covering an upper surface and a side surface of the first gate electrode; and a second gate electrode on the first interlayer insulating film corresponding to the position of the first gate electrode. A second gate electrode forming step for forming, and a second interlayer insulating film forming step for forming a second interlayer insulating film covering the upper surface and the side surface of the second gate electrode, wherein the second interlayer insulating film is formed. A first antireflection film for preventing reflection of visible light is formed on the entire surface of the substrate, and the second antireflection film is formed on the first antireflection film.

  According to another aspect of the present invention, there is provided a method for manufacturing a solid-state imaging device, wherein the semiconductor device manufactured by the method for manufacturing a semiconductor device of the present invention photoelectrically converts incident light for each predetermined surface region of a semiconductor substrate adjacent to the first gate electrode. A light receiving portion for generating a signal charge is formed, and an island-shaped first antireflection film for preventing visible light reflection is formed on the central region of the light receiving portion. Achieved.

  The solid-state imaging device of the present invention is a solid-state imaging device manufactured by the above-described solid-state imaging device manufacturing method of the present invention, except for the central region of the predetermined surface region of the semiconductor substrate adjacent to the first gate electrode that operates as the charge transfer electrode. An interlayer insulating film is formed, and a central region of a predetermined surface region of the semiconductor substrate adjacent to the first gate electrode is an edge portion of an island-shaped antireflection film in a visible light region as the first antireflection film Is formed in a square shape without becoming a taper shape, thereby achieving the above object.

  Preferably, in the solid-state imaging device according to the present invention, a first interlayer insulating film is disposed on an upper surface and a side surface of the first gate electrode, and a first interlayer insulating film corresponding to the first gate electrode is formed on the first interlayer insulating film. Two gate electrodes are disposed, and a second interlayer insulating film is disposed on the top and side surfaces of the second gate electrode.

  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 second antireflection film is formed on the entire surface of the semiconductor substrate on which the semiconductor device is formed to prevent exposure from being reflected and to dissolve in a developer, and a resist pattern having a predetermined shape is formed on the second antireflection film. Form.

  Thereby, since the resist pattern having a predetermined shape is formed on the second antireflection film which prevents the reflection of the exposure and dissolves in the developer, the exposure is absorbed by the second antireflection film and the reflected light of the exposure is suppressed. It is possible to prevent constriction of the side surface of the photoresist film due to reflected light, and it is possible to easily dissolve and remove the second antireflection film other than directly under the photoresist pattern with a developer. The film pattern directly below can be formed as a film pattern having the same shape as the resist pattern with high dimensional accuracy.

  As described above, according to the present invention, since the resist pattern having a predetermined shape is formed on the second antireflection film that prevents exposure and reflects the developer, the second antireflection film absorbs the exposure and reflects the exposure. Light is suppressed, it is possible to prevent constriction of the side surface of the photoresist film due to reflected light, and it is possible to easily dissolve and remove the second antireflection film other than just under the photoresist pattern with a developer. Therefore, the film pattern immediately below the resist pattern can be formed as a film pattern having the same shape as the resist pattern with high dimensional accuracy.

It is a longitudinal cross-sectional view which shows typically the example of a principal part structure of the semiconductor device manufactured by the manufacturing method of the semiconductor device in Embodiment 1 of this invention. (A)-(d) is the principal part longitudinal section which shows typically to the 1st gate electrode formation process for demonstrating the manufacturing method of the semiconductor device using the formation method of the resist pattern which concerns on Embodiment 1 of this invention. FIG. (A)-(c) is to the 2nd gate electrode formation process following FIG.2 (d) for demonstrating the manufacturing method of the semiconductor device using the formation method of the resist pattern which concerns on Embodiment 1 of this invention. It is a principal part longitudinal cross-sectional view shown typically. (A)-(c) is a model until the nitride film formation process following FIG.3 (c) for demonstrating the manufacturing method of the semiconductor device using the formation method of the resist pattern which concerns on Embodiment 1 of this invention. It is a principal part longitudinal cross-sectional view shown in figure. FIGS. 4A to 4C are schematic diagrams up to a nitride film forming step subsequent to FIG. 4C for explaining a method for manufacturing a semiconductor device using the resist pattern forming method according to the first embodiment of the present invention. It is a principal part longitudinal cross-sectional view shown in FIG. It is a longitudinal cross-sectional view which shows typically the example of a principal part structure of the solid-state image sensor manufactured by the manufacturing method of the solid-state image sensor in Embodiment 2 of this invention. (A)-(c) is the principal part longitudinal cross-section which shows typically the anti-reflective film formation process for demonstrating the manufacturing method of the solid-state image sensor using the formation method of the resist pattern which concerns on Embodiment 2 of this invention. FIG. It is a block diagram which shows the example of schematic structure of the electronic information device which used the solid-state image sensor of Embodiment 2 of this invention for the imaging part as Embodiment 3 of this invention. (A)-(d) is a principal part longitudinal cross-sectional view which shows typically to the 1st gate electrode formation process for demonstrating the manufacturing method of the solid-state image sensor including the formation method of the conventional resist pattern. FIGS. 9A to 9C schematically show a process up to a second gate electrode formation step subsequent to FIG. 9D for explaining a method for manufacturing a solid-state imaging device using a conventional resist pattern formation method. FIG. (A)-(c) are the principal parts which show typically to the nitride film film-forming process following FIG.10 (c) for demonstrating the manufacturing method of the solid-state image sensor using the formation method of the conventional resist pattern. It is a longitudinal cross-sectional view. (A)-(c) is a principal part longitudinal section which shows typically to the nitride film formation process following FIG.11 (c) for demonstrating the manufacturing method of the solid-state image sensor using the formation method of the conventional resist pattern. FIG. (A) And (b) is a principal part longitudinal cross-sectional view for demonstrating the problem of the formation method of the conventional resist pattern described in patent document 1. FIG.

  Embodiment 1 of a semiconductor device manufacturing method using the resist pattern forming method of the present invention will be described in detail below with reference to the drawings, and a semiconductor device manufacturing method using the resist pattern forming method of the present invention will be described below. The second embodiment is applied to a method for manufacturing a solid-state image sensor, and is described in detail with reference to the drawings. Then, the solid-state image sensor manufactured by the method for manufacturing a solid-state image sensor is used as an image input device for an imaging unit. Embodiment 3 of an electronic information device such as a camera-equipped mobile phone device will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a longitudinal cross-sectional view schematically showing an exemplary configuration of a main part of a semiconductor device manufactured by the method for manufacturing a semiconductor device according to Embodiment 1 of the present invention.

  In FIG. 1, the semiconductor device 20 according to the first embodiment is formed on a silicon substrate 1 as a semiconductor substrate, and is formed by stacking a gate oxide film 2, a gate nitride film 3, and a gate HTO film 4 in this order. The first gate electrode 5A is disposed, the first interlayer insulating film 7 is disposed on the upper surface and the side surface of the first gate electrode 5A, and similarly, the second gate electrode 8A is disposed thereon. A second interlayer insulating film 10 is disposed on the top and side surfaces of the two-gate electrode 8A. Thus, the first gate electrode 5A and the second gate electrode 8A are stacked and formed in two upper and lower stages. Except for the central region between the adjacent first gate electrodes 5A, the second interlayer insulating film 10A is left with a predetermined thickness, and the central region between the adjacent first gate electrodes 5A is used as an antireflection film in the visible light region. The acting island-shaped nitride film 11A is formed with high dimensional accuracy without the corners being tapered.

  In this case, the first gate electrode 5A corresponds to the gate electrode of the transistor in the peripheral circuit section for performing signal processing and element control, and the second gate electrode 8A corresponds to each drive region of the transistor constituting the peripheral circuit section. And circuit wiring connected to the gate electrode. On the surface side of the silicon substrate 1 between the adjacent first gate electrodes 5A, a light receiving element that receives, for example, optical data from a pickup device is disposed as a part other than the light receiving portion (photodiode) of the solid-state imaging element. May be. In addition to this, the method for forming a resist pattern of the present invention can be applied to the formation of a capacitor such as a charge pump circuit having a stepped portion around it.

  Hereinafter, a method for manufacturing the semiconductor device 20 having the above configuration will be described in detail with reference to FIGS.

  2A to 2D schematically illustrate the first gate electrode formation process for explaining the method for manufacturing the semiconductor device 20 using the resist pattern forming method according to the first embodiment of the present invention. 3A to FIG. 3C are diagrams for explaining a method of manufacturing the semiconductor device 20 using the resist pattern forming method according to the first embodiment of the present invention. FIG. 4A to FIG. 4C schematically illustrate a main pattern longitudinal sectional view up to the second gate electrode forming step subsequent to (d), and FIGS. 4A to 4C illustrate a resist pattern forming method according to the first embodiment of the present invention. FIG. 5A to FIG. 5C are main part longitudinal sectional views schematically showing a nitride film forming process subsequent to FIG. 3C for explaining the manufacturing method of the semiconductor device 20 used. Manufacturing method of semiconductor device 20 using the resist pattern forming method according to Embodiment 1 of the present invention Until the nitride film forming process subsequent to FIG. 4 (c) for explaining to an essential part longitudinal cross sectional view schematically showing.

First, as shown in FIG. 2A, a gate oxide film 2 which is a SiO ₂ film is formed on a silicon substrate 1 as a semiconductor substrate, a gate nitride film 3 is further formed on the gate oxide film, and a gate is further formed. A gate HTO film 4 is formed on the nitride film 3, and a first polysilicon film 5 is formed on the gate HTO film 4. The first polysilicon film 5 is doped to provide conductivity because it becomes the first gate electrode.

  Further, as shown in FIG. 2B, a photoresist pattern 6 serving as a mask for processing the first gate electrode is formed on the doped first polysilicon film 5. That is, a photoresist film material is formed on the first polysilicon film 5, and exposed and developed so that the photoresist film remains at a predetermined position on the first polysilicon film 5 where the first gate electrode is formed. By patterning into a predetermined shape, a photoresist pattern 6 for processing the first gate electrode is formed on the first polysilicon film 5.

  Subsequently, as shown in FIG. 2C, the pre-doped first polysilicon film 5 is etched by using the photoresist pattern 6 on the first polysilicon film 5 as a mask, and each of the first polysilicon film 5 is in a predetermined position. A gate electrode 5A is formed.

  In this way, the first gate electrode 5A can be formed on the gate HTO film 4 by the steps of FIGS. 2A to 2C, respectively.

  Thereafter, as shown in FIG. 2D, the first gate electrode 5A formed in a predetermined shape from the pre-doped first polysilicon film 5 is subjected to surface thermal oxidation so that the upper surface and side surfaces of the first gate electrode 5A are obtained. A first interlayer insulating film 7 is formed to cover.

  Next, as shown in FIG. 3A, a second polysilicon film 8 is formed on the first interlayer insulating film 7 and the gate HTO film 4, and the formed second polysilicon film 8 is a second gate. Since it becomes an electrode, it is doped to provide conductivity.

  Subsequently, as shown in FIG. 3B, a photoresist pattern 9 is formed on the doped second polysilicon film 8 for processing the second gate electrode. That is, a photoresist film material is formed on the second polysilicon film 8, and exposed and developed so that the photoresist film remains above the first gate electrode 5A where the second gate electrode is formed. A photoresist pattern 9 having a predetermined shape is formed on the second polysilicon film 8 by patterning.

  Thereafter, as shown in FIG. 3C, the pre-doped second polysilicon film 8 is etched using the photoresist pattern 109 on the second polysilicon film 8 as a mask, and the gate HTO film 4 is gated. The nitride film 3 is further etched away to the middle of the gate oxide film 2, and second gate electrodes 8A are formed at predetermined central positions on the first interlayer insulating film 7 corresponding to the positions of the first gate electrodes 5A.

  In this way, the second gate electrode 8A can be formed on the first interlayer insulating film 7 by the steps of FIGS. 3A to 3C. As a result, a step portion is formed by the upper and lower two-stage first gate electrode 105A and second gate electrode 108A.

  Next, as shown in FIG. 4A, after removing the photoresist pattern 9 remaining on the second gate electrode 8A formed in an island shape, as shown in FIG. The surface of the electrode 8A is thermally oxidized to form a second interlayer insulating film 10 that covers the top and side surfaces of the first gate electrode 8A, and the gate oxide film 2 remaining between the gate electrodes is also thermally oxidized to form a second interlayer insulating film. A film 10 is formed.

  Subsequently, as shown in FIG. 4C, a nitride film 11 in a visible light region of a SiN film, which is an inorganic film, is formed as a first antireflection film on the entire surface of the substrate on the second interlayer insulating film 10. Only the thickness is deposited. Further, an ultraviolet antireflection film 12 that is an organic film that absorbs ultraviolet light to prevent reflection and dissolves with a developing solution and a stripping solution is formed on the entire surface of the nitride film 11 as a second antireflection film. .

  The organic ultraviolet antireflection film 12 is an ultraviolet antireflection film (manufactured by Nissan Chemical Co., Ltd.) that dissolves in response to a developer (alkali).

  Next, as shown in FIG. 5A, the nitride film 11 is formed on the central region of the ultraviolet antireflection film 12 between the gate electrodes (or on the central region of the predetermined surface region of the silicon substrate 1 adjacent to the gate electrode). A photoresist pattern 13 is formed for the shape processing. That is, a photoresist film material is deposited on the entire surface of the substrate on the ultraviolet antireflection film 12, and the photo is formed above the central region between the gate electrodes (or on the central region of the predetermined surface region of the silicon substrate 1 adjacent to the gate electrode). A photoresist pattern 13 for processing a nitride film is formed on the ultraviolet antireflection film 12 by patterning into a predetermined shape by exposure and development so that the resist film remains. At this time, since the ultraviolet exposure is absorbed by the underlying ultraviolet antireflection film 12, the reflected light of the ultraviolet exposure is less likely to occur and the constriction B (halation) is constricted on the side surface of the photoresist film by the reflected light from the stepped portion as in the prior art. Will not occur. Further, the ultraviolet antireflection film 12 indicated by a broken line other than directly under the photoresist pattern 13 can be dissolved and removed by a subsequent developer.

  Subsequently, as shown in FIG. 5B, the second interlayer insulating film 10 is formed from the nitride film 11 using the nitride film 11 in the central region between the gate electrodes and the photoresist pattern 13 on the ultraviolet antireflection film 12 as a mask. A dry etching process is performed to remove the nitride film 11 and the second interlayer insulating film 10 in the middle to leave a predetermined thickness as the second interlayer insulating film 10A of the SiOn film, above the central region between the gate electrodes, It is possible to form an island-shaped nitride film 11 </ b> A that is a visible light region antireflection film formed with high dimensional accuracy by forming an edge portion (corner portion) without forming a taper shape. Thus, the line width of the island-shaped nitride film 11A can be accurately controlled.

  Further, as shown in FIG. 5C, the photoresist pattern 13 remaining on the ultraviolet reflection preventing film 12 having a predetermined shape is peeled off and removed. At this time, the ultraviolet antireflection film 12 directly under the photoresist pattern 13 is also easily dissolved and removed in the stripping solution. In this way, even when the pattern is a high step pattern, the ultraviolet antireflection film 12 can be removed after the resist pattern is formed during the resist peeling process.

  As described above, in the method of manufacturing the semiconductor device 20 according to the first embodiment, the first gate electrode forming step of forming the first gate electrode 5A on the gate oxide film 2 formed on the silicon substrate 1, and the first gate electrode A first interlayer insulating film forming step for forming a first interlayer insulating film 7 covering the upper surface and side surfaces of 5A, and a second gate electrode 8A is formed on the first interlayer insulating film 7 corresponding to the position of the first gate electrode 5A A second gate electrode forming step, a second interlayer insulating film forming step for forming a second interlayer insulating film 10 covering the upper surface and side surfaces of the second gate electrode 8A, and the entire surface of the substrate on which the second interlayer insulating film 10 is formed. A nitride film forming step for forming a nitride film 11 on the substrate; and an ultraviolet reflection film for forming an ultraviolet antireflection film 12 that absorbs ultraviolet rays to prevent reflection and dissolves with a developing solution over the entire surface of the substrate on which the nitride film 11 is formed. A protective film forming step; A photoresist pattern forming step for forming a photoresist pattern 13 for processing the shape of the nitride film 11 on the central region of the ultraviolet antireflection film 12 between the gate electrodes, and the nitride film 11 using the photoresist pattern 13 as a mask. And a nitride film forming step of forming an island-shaped nitride film 11A formed with high dimensional accuracy without tapering the corners above the central region between the gate electrodes by etching. Yes.

  The method of forming the resist pattern 13 used in the method for manufacturing the semiconductor device 20 is to prevent the reflection of ultraviolet rays on the entire surface of the silicon substrate 1 on which the semiconductor device is formed as an antireflection film as a second antireflection film that is soluble in the developer. A film 12 is formed, and a resist pattern 13 having a predetermined shape is formed on the ultraviolet antireflection film 12. That is, a nitride film forming step for forming a nitride film 11 as a first antireflection film for preventing reflection of visible light on the entire surface of the silicon substrate 1, and exposing the exposure on the nitride film 11 and developing the developer The ultraviolet antireflection coating film forming step for forming the ultraviolet antireflection coating 12 that is soluble in the film and the shape of the ultraviolet antireflection coating 12 on the central region of the predetermined surface region of the silicon substrate 1 adjacent to the gate electrode constituting the semiconductor device A photoresist pattern forming step for forming a photoresist pattern 13 for processing. At this time, the ultraviolet ray antireflection film 12 absorbs the exposure, and the reflected light of the exposure is suppressed, so that the constriction of the side surface of the photoresist film due to the reflected light can be prevented. Further, the ultraviolet antireflection film 12 other than just below the photoresist pattern 13 can be dissolved and removed with a developer.

  Therefore, in the resist pattern forming method of the present invention, a photoresist film material is applied on the UV antireflection film 12 that is dissolved by WET, and is exposed and developed to a predetermined shape to form a photoresist pattern 13. The ultraviolet antireflection film 12 can also be dissolved and removed when the photoresist pattern 13 is removed after the etching. Accordingly, the film pattern of the ultraviolet antireflection film 12 and the nitride film 11 immediately below the resist pattern 13 can be formed as a film pattern having the same shape as the photoresist pattern 13 with high dimensional accuracy.

(Embodiment 2)
In the first embodiment, the semiconductor device manufacturing method using the resist pattern forming method of the present invention has been described. In the second embodiment, a solid-state imaging device manufacturing method using the resist pattern forming method of the present invention. Will be described.

  FIG. 6 is a vertical cross-sectional view schematically illustrating an exemplary configuration of a main part of a solid-state image sensor manufactured by the solid-state image sensor manufacturing method according to Embodiment 2 of the present invention.

  In FIG. 6, the solid-state imaging device 30 according to the second embodiment has a stacked structure in which a gate oxide film 2, a gate nitride film 3, and a gate HTO film 4 are stacked in this order on a silicon substrate 1 as a semiconductor substrate. The first gate electrode 5A is disposed on the upper surface and the side surface of the first gate electrode 5A. Similarly, the second gate electrode 8A is disposed on the first gate electrode 5A. The second interlayer insulating film 10 is disposed on the upper surface and the side surface of the second gate electrode 8A, and two step portions are disposed. Thus, the first gate electrode 5A and the second gate electrode 8A are stacked and formed in two upper and lower stages. On the surface side of the silicon substrate 1 between the adjacent first gate electrodes 5A, the first gate electrode 5A is doped with impurity ions in a self-aligning manner, and incident light is photoelectrically converted as a light receiving element to generate a signal charge. An impurity diffusion region of the photodiode PD is formed. Except for the central region on the photodiode PD, the second interlayer insulating film 10A is left to a predetermined thickness, and the central region on the photodiode PD has an island shape that acts as a first antireflection film in the visible light region. The nitride film 11A is formed in a square shape with a high dimensional accuracy without the edge portion (corner portion) being tapered as in the prior art.

  In this case, the first gate electrode 5A is a charge transfer electrode for reading the signal charge of the photodiode PD which is a light receiving portion and transferring the charge. The second gate electrode 8A on the first gate electrode 5A may constitute a wiring.

  A light shielding film 14 is formed on the second gate electrode 8A and the second interlayer insulating film 10A in order to prevent incident light from being reflected by the first gate electrode 5A and the second gate electrode 8A and generating noise. Yes. Further, an opening of the light shielding film 14 is formed above the photodiode PD. An interlayer insulating film is provided so as to fill a step portion between the adjacent light shielding films 14, and an inner lens 15 is disposed using a recess above the photodiode PD of the interlayer insulating film. Further, a color filter 17 is disposed via a planarizing film 16 on the in-layer lens 15. On the color filter 17, a microlens 19 for condensing incident light on the central portion of the photodiode PD in plan view (island-shaped nitride film 11 </ b> A) together with the intralayer lens 15 via the planarizing film 18. Is arranged. As described above, the solid-state imaging device 30 of the second embodiment is configured.

  In the following, the manufacturing method of the solid-state imaging device 30 using the resist pattern forming method of the present invention is the same as in FIG. 2 to FIG. 5 except for the configuration of the phototransistor PD in the second embodiment. This will be described in detail with reference to FIG.

  FIG. 7A to FIG. 7C are views showing a nitride film formation subsequent to FIG. 4C for explaining a method for manufacturing a solid-state imaging device using the resist pattern forming method according to the second embodiment of the present invention. It is a principal part longitudinal cross-sectional view which shows to a process typically.

  As shown in FIG. 7A, the shape of the nitride film 11 is formed on the center region of the inorganic ultraviolet antireflection film 12 that absorbs ultraviolet rays to prevent reflection and dissolves in the developer above the photodiode PD. For this purpose, a photoresist pattern 13 is formed. That is, a photoresist film material is formed on the entire surface of the substrate on the ultraviolet antireflection film 12, and is formed on the central region of the ultraviolet antireflection film 12 between the gate electrodes (or a predetermined surface region of the silicon substrate 1 adjacent to the gate electrode (light receiving). A photoresist pattern 13 for processing a nitride film is formed on the ultraviolet antireflection film 12 by patterning into a predetermined shape by exposure and development so that the photoresist film remains in the central region of the region). At this time, since the UV exposure is absorbed by the underlying UV antireflection film 12, the reflected light from the UV exposure by the stepped portion is hardly generated, and the light reflected from the stepped portion is constricted on the side surface of the photoresist film. B (halation) does not occur. Further, the ultraviolet antireflection film 12 indicated by a broken line other than just below the photoresist pattern 13 is dissolved and removed by a developer at the time of subsequent pattern formation.

  Subsequently, as shown in FIG. 7B, the nitride film 11 in the central region above the photodiode PD and the photoresist pattern 13 on the ultraviolet antireflection film 12 are used as a mask from the nitride film 11 to the second interlayer insulating film 10. Is etched away to the middle of the nitride film 11 and the second interlayer insulating film 10 to leave a predetermined thickness as the second interlayer insulating film 10A of the SiOn film, and in the central region above the photodiode PD, The island-shaped nitride film 11A formed with high dimensional accuracy can be formed without the portion being tapered. Thus, the line width of the island-shaped nitride film 11A can be accurately controlled.

  Further, as shown in FIG. 7C, the photoresist pattern 13 remaining on the ultraviolet reflection preventing film 12 having a predetermined shape is peeled off and removed. At this time, the ultraviolet antireflection film 12 directly under the photoresist pattern 13 is also dissolved in the stripping solution and removed. As described above, even if the pattern is a high step pattern, the ultraviolet antireflection film 12 can be removed by removing the resist after etching after forming the resist pattern.

  Therefore, according to the second embodiment, as in the case of the first embodiment, the ultraviolet antireflection film 12 and the nitride film 11 immediately below the photoresist pattern 13 are formed with the same dimensional accuracy as the photoresist pattern. 13 can be formed as a film pattern having the same shape as 13.

(Embodiment 3)
In the third embodiment, an example of an electronic information device in which the solid-state imaging device manufactured by the solid-state imaging device manufacturing method of the second embodiment is used as an image input device for an imaging unit will be described in detail.

  FIG. 8 is a block diagram illustrating a schematic configuration example of an electronic information device using the solid-state imaging device 30 according to the second embodiment of the present invention as an imaging unit as the third embodiment of the present invention.

  In FIG. 8, an electronic information device 90 according to the third embodiment includes a solid-state imaging device 91 that obtains a color image signal by performing predetermined signal processing on an imaging signal from the solid-state imaging device 30 according to the second 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 means 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 image pickup device 91 are subjected to predetermined signal processing for communication, and then communication processing is enabled. A communication unit 94 such as a transmission / reception device, and a printer that can perform print processing after performing predetermined print signal processing on a color image signal from the solid-state imaging device 91 for printing. And an image output 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, on the basis of the color image signal from the solid-state imaging device 91, the image is displayed on the display screen, or the image is output by the image output means 95 on the paper. (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 and second embodiments, as a method of forming the resist pattern 13, exposure is prevented from being reflected on the entire surface of the silicon substrate 1 on which the semiconductor device is formed and is dissolved in a developer. An ultraviolet antireflection film 12 is formed, and a resist pattern 13 having a predetermined shape is formed on the ultraviolet antireflection film 12. That is, a nitride film forming step for forming a nitride film 11 for preventing visible light reflection on the entire surface of the silicon substrate 1 on which the semiconductor device is formed, and an ultraviolet ray for forming an ultraviolet antireflection film 12 on the nitride film 11. Antireflection film forming step and photoresist pattern forming step of forming a photoresist pattern 13 for shape processing of nitride film 11 on a central region of a predetermined surface region of a silicon substrate adjacent to a gate electrode constituting a semiconductor device And have. Thus, the object of the present invention is achieved, in which the film pattern of the nitride film 11 immediately below the resist pattern 13 can be accurately formed as the film pattern of the nitride film 11 having the same shape as the resist pattern 13 with high dimensional accuracy. can do.

  As mentioned above, although this invention has been illustrated using preferable Embodiment 1-3 of this invention, this invention should not be limited and limited to this Embodiment 1-3. 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 to 3 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 is a method for forming a resist pattern in a lithography process, a method for manufacturing a semiconductor device using the resist pattern, and a method for manufacturing the semiconductor device. The semiconductor device includes, for example, a semiconductor element that captures an image by photoelectrically converting image light from a subject. Manufacturing method of solid-state imaging device, solid-state imaging device manufactured by this manufacturing method of solid-state imaging device, and digital cameras such as digital video cameras and digital still cameras using this solid-state imaging device as an image input device in an imaging unit, In a field of electronic information equipment such as an image input camera such as a surveillance camera, a scanner device, a facsimile device, a television telephone device, a camera-equipped mobile phone device, etc., on the second antireflection film that prevents reflection from being reflected and dissolves in the developer. A resist pattern having a predetermined shape is formed on the second antireflection film. As a result, the exposure light is absorbed and the reflected light of the exposure is suppressed, so that the constriction of the side surface of the photoresist film due to the reflected light can be prevented. Since it can be dissolved and removed, the film pattern immediately below the resist pattern can be formed as a film pattern having the same shape as the resist pattern with high dimensional accuracy.

DESCRIPTION OF SYMBOLS 1 Silicon substrate 2 Gate oxide film 3 Gate nitride film 4 Gate HTO film 5 1st polysilicon film 5A 1st gate electrode 6, 9, 13 Photoresist pattern 7 1st interlayer insulation film 8 2nd polysilicon film 8A 2nd gate Electrode 10, 10A Second interlayer insulating film 11, 11A Nitride film 12 Ultraviolet antireflection film 14 Light shielding film 15 In-layer lens 16, 18 Planarization film 17 Color filter 19 Micro lens 20 Semiconductor device 30 Solid-state imaging device PD Photodiode 90 Electron Information equipment 91 Solid-state imaging device 92 Memory unit 93 Display means 94 Communication means 95 Image output means

Claims (12)

A second antireflection film is formed on the entire surface of the semiconductor substrate on which the semiconductor device is formed to prevent reflection of exposure and to dissolve in a developer, and a resist pattern having a predetermined shape is formed on the second antireflection film. Using the photoresist pattern formed by the forming method as a mask, the first antireflection film that prevents reflection of visible light is etched, and a central region of a predetermined surface region of the semiconductor substrate adjacent to the gate electrode constituting the semiconductor device , the edge portion have a first anti-reflection film forming step for forming a first antireflection film island shape became angular without tapers,
The method of manufacturing a semiconductor device, wherein the second antireflection film is made of a material that is soluble not only in the photoresist pattern developer but also in the photoresist pattern stripping solution . The resist pattern forming method includes: a first antireflection film forming step of forming a first antireflection film for preventing visible light reflection over the entire surface of the semiconductor substrate on which the semiconductor device is formed;
A second antireflection film forming step of forming the second antireflection film on the first antireflection film;
And a photoresist pattern forming step of forming a photoresist pattern for shape processing of the first antireflection film on a central region of a predetermined surface region of a semiconductor substrate adjacent to a gate electrode constituting the semiconductor device. 2. A method for manufacturing a semiconductor device according to 1. 3. The photoresist pattern forming step according to claim 1, wherein exposure is absorbed by the second antireflection film and reflected light of the exposure is suppressed to prevent constriction of a side surface of the photoresist film due to the reflected light. A method for manufacturing a semiconductor device . 3. The method of manufacturing a semiconductor device according to claim 1, wherein, in the photoresist pattern forming step, the second antireflection film other than immediately below the photoresist pattern is dissolved and removed with a developer. The method of manufacturing a semiconductor device according to claim 2, wherein the first antireflection film is an inorganic film, and the second antireflection film is an organic film. The method of manufacturing a semiconductor device according to claim 1, wherein the exposure is ultraviolet light. In the first antireflection film forming step, when the photoresist pattern on the second antireflection film is peeled and removed after the etching process, the second antireflection film immediately below the photoresist pattern is also dissolved. The method of manufacturing a semiconductor device according to claim 1 , wherein the semiconductor device is removed. A first gate electrode forming step of forming a first gate electrode constituting the semiconductor device on a gate oxide film formed on a semiconductor substrate;
A first interlayer insulating film forming step of forming a first interlayer insulating film covering the upper surface and side surfaces of the first gate electrode;
A second gate electrode forming step of forming a second gate electrode on the first interlayer insulating film corresponding to the position of the first gate electrode;
A second interlayer insulating film forming step of forming a second interlayer insulating film covering the upper surface and the side surface of the second gate electrode,
The first antireflection film for preventing reflection of visible light is formed on the entire surface of the substrate on which the second interlayer insulating film is formed, and the second antireflection film is formed on the first antireflection film. 2. A method for manufacturing a semiconductor device according to 1 . The semiconductor device manufactured by the method of manufacturing a semiconductor device according to any one of claims 1-8, wherein the predetermined surface region of the semiconductor substrate adjacent to the first gate electrode, the signal charges by photoelectric conversion of incident light A solid-state imaging device manufacturing method in which an island-shaped first antireflection film that prevents reflection of visible light is formed on a central region of the light receiving unit. 10. The solid-state imaging device manufactured by the method for manufacturing a solid-state imaging device according to claim 9 , wherein an interlayer insulating film is formed in a region other than a central region of a predetermined surface region of the semiconductor substrate adjacent to the first gate electrode that operates as a charge transfer electrode. In the central region of the predetermined surface region of the semiconductor substrate that is formed and adjacent to the first gate electrode, the edge portion of the island-shaped antireflection film in the visible light region is tapered as the first antireflection film. A solid-state image sensor formed in a square shape. A first interlayer insulating film is disposed on the top and side surfaces of the first gate electrode, a second gate electrode is disposed on the first interlayer insulating film corresponding to the first gate electrode, and the second gate electrode The solid-state imaging device according to claim 10 , wherein a second interlayer insulating film is disposed on the upper surface and side surfaces of the solid-state imaging device. An electronic information device using the solid-state imaging device according to claim 10 as an image input device in an imaging unit.

Images