JP2007335694A - Solid-state image pickup device, method of manufacturing same, and electronic information equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a light-reception sensitivity characteristic in the light-receiving opening of a light-blocking film and reduce and suppress a smear without impeding a hydrogen annealing effect to a photoelectric converter. <P>SOLUTION: A light-blocking film 12 is formed on a photoelectric converter 2 and a charge transfer electrode 7, via a first silicon oxide film 8a and a second silicon oxide film 11. Further, a third silicon oxide film 13 is formed on it. A light-receiving opening 14 is formed in the light-blocking film 12 and the third silicon oxide film 13 at one time. Since there is only a silicon oxide film 14a between the light-blocking film 12 and the photoelectric converter 2, a level difference is alleviated and a smear can be reduced. A reflection-preventing film 15 is deposited on it. Patterning is carried out such that the reflection-preventing film covers a part of the charge transfer electrode 7 from the light-receiving opening 14 on the photoelectric converter 2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a solid-state imaging device in which a plurality of light-receiving units that receive subject light and generate respective signal charges are two-dimensionally arranged, a manufacturing method thereof, and an imaging unit using the solid-state imaging device as an image input device. The present invention relates to an electronic information device such as a digital video camera and a digital still camera, and an image input camera, a scanner, a facsimile, a camera-equipped mobile phone device, and the like.

  In this type of conventional solid-state imaging device, a plurality of light receiving portions are arranged in a two-dimensional manner as a plurality of pixel portions, and subject light from a subject incident through each microlens is each light receiving portion. Each photoelectric conversion unit (photodiode) receives the light and converts it to each signal charge, and each image charge is output by sequentially detecting each signal charge. For example, in a solid-state imaging device in which a charge coupled device (Charge Coupled Device, hereinafter referred to as “CCD”) is arranged, each signal charge obtained by photoelectrically converting subject light in each photoelectric conversion unit is converted into a vertical charge via each readout unit. Each signal charge is read out from the vertical charge transfer unit to the horizontal charge transfer unit by the charge transfer driving by the charge transfer pulse of the vertical charge transfer unit. The detection unit outputs the image pickup signals to the outside.

  As a method for improving the signal charge detection sensitivity of such a solid-state imaging device, for example, Patent Literature 1 and Patent Literature 2 describe that subject light incident on each photoelectric conversion unit is prevented from being reflected by the substrate surface. In order to do this, the following solid-state imaging device has been proposed.

  First, a conventional solid-state imaging device disclosed in Patent Document 1 among Patent Document 1 and Patent Document 2 will be described in detail with reference to FIG.

  FIG. 4 is a longitudinal sectional view of a main part of a conventional solid-state imaging device disclosed in Patent Document 1. FIG. 4 shows a vertical cross-sectional configuration for each pixel unit including the photoelectric conversion unit and the vertical transfer unit.

  In FIG. 4, a conventional solid-state imaging device 20 includes a photoelectric conversion unit 22 constituting a pixel unit as a light receiving unit that converts incident light into a signal charge on a semiconductor substrate 21, and a signal charge from the photoelectric conversion unit 22. A charge readout unit 23 for reading out a signal, a vertical charge transfer region 24 for transferring a signal charge read out by the charge readout unit 23 in the vertical direction, and an electrical separation from an adjacent pixel unit. And a channel stop unit 25.

  In the solid-state imaging device 20, a charge transfer electrode 27 is formed on the vertical charge transfer region 24 via a gate insulating film 26. By driving the charge transfer electrode 27 with a charge transfer drive pulse, The signal charges read from the photoelectric conversion unit 22 to the vertical charge transfer region 24 via the charge reading unit 23 are sequentially transferred in the vertical direction.

  Further, in the solid-state imaging device 20, the first silicon oxide films 28 a and 28 b are formed on the charge transfer electrode 27 and the photoelectric conversion unit 22 by thermal oxidation, and the first silicon oxide films 28 a and 28 b on the light receiving portion of the photoelectric conversion unit 22 are formed. An antireflection film 29 is formed on the one silicon oxide film 28b. A second silicon oxide film 31 and a light shielding film 32 are formed in this order so as to cover the substrate portion. The light-shielding film 32 is formed with light receiving openings 32a so as to expose the tops of the respective photoelectric conversion portions 22. The second silicon oxide film 31 on the antireflection film 29 is formed by exposing the antireflection film 29 when the light shielding film 32 is formed and the light receiving opening 32a is formed by dry etching. It is provided in order to prevent the decrease and to maintain the insulation between the charge transfer electrode 27 and the light shielding film 32.

  Below, the manufacturing method of the conventional solid-state image sensor 20 proposed by patent document 1 is demonstrated.

  5 (a) to 5 (c) and FIGS. 6 (d) to 6 (f) are main part longitudinal sectional views for explaining each step of the method of manufacturing the solid-state imaging device 20 of FIG. is there.

  First, as shown in FIG. 5A, the photoelectric conversion unit 22, the charge reading unit 23, the charge transfer region 24, and the channel stop unit 25 are formed in this order in the horizontal direction by impurity ion implantation processing into the semiconductor substrate 21. To do. A gate insulating film 26 made of an ONO film or the like is formed on the substrate portion. Further, a charge transfer electrode 27 is formed on the charge transfer region 24 through a gate insulating film 26. First silicon oxide films 28a and 28b are formed on these charge transfer electrodes 27 and photoelectric conversion portion 22 as a protective film for ion implantation by a thermal oxidation process.

  Next, as shown in the resist pattern forming step for forming the antireflection film in FIG. 5B, a silicon nitride film 29a (SiN film) as a film material to be the antireflection film 29 is formed on this substrate portion by LPCVD. Alternatively, the resist pattern 30 is deposited by the plasma CVD method, and a resist pattern 30 for forming the antireflection film 29 is patterned on the corresponding silicon nitride film (SiN film) on the light receiving portion of the photoelectric conversion unit 22 by using a photolithography technique. To do.

  Thereafter, as shown in the antireflection film forming step of FIG. 5C, the silicon nitride film 29a (SiN film) not covered with the resist pattern 30 is etched away by dry etching, and each photoelectric conversion unit 22 is removed. An antireflection film 29 is formed at a corresponding position on the light receiving portion.

  Further, as shown in the light shielding film material deposition step of FIG. 6D, a second silicon oxide film 31 is deposited on the entire surface of the substrate portion by LPCVD, and then tungsten (on the second silicon oxide film 31 is deposited). A light shielding film material 32b made of W) or the like is deposited.

  Subsequently, as shown in the resist pattern forming step for forming the light shielding film in FIG. 6E, a resist pattern material is deposited on the light shielding film material 32b made of tungsten (W) or the like, and using a photolithography technique, The resist pattern 33 is patterned so as to have an opening 33a opened above the light receiving portion of each photoelectric conversion unit 22.

  Further, as shown in the light shielding film forming step of FIG. 6F, the light shielding film material 32b corresponding to the opening 33a of the resist pattern 33 is etched away by a dry etching method, so that a light receiving opening is formed in the light shielding film material 32b. A portion 32a is formed. Thereby, the light shielding film 32 opened above the light receiving part of each photoelectric conversion unit 22 is formed. Thereafter, the resist pattern 33 on the light shielding film 32 is removed.

  Although the illustration of subsequent steps is omitted, the solid-state imaging device 20 is manufactured by a general method and a manufacturing method according to the steps.

  In the solid-state imaging device 20 having a structure as proposed in Patent Document 1, the laminated structure of the film in the light receiving opening 32a on the semiconductor substrate 21 includes a first silicon oxide film 28b, an antireflection film 29, and a second film. A silicon oxide film 31 is formed. The antireflection film 29 has low reflectivity, and can prevent the subject light collected by the microlens and incident from being reflected from the surface of the semiconductor substrate 21 (photoelectric conversion unit 22). Therefore, there is an advantage that the light receiving sensitivity in the photoelectric conversion unit 22 can be improved.

  Next, a conventional solid-state imaging device disclosed in Patent Document 2 will be described in detail with reference to FIG.

  FIG. 7 is a longitudinal sectional view of an essential part of a conventional solid-state imaging device disclosed in Patent Document 2. FIG. 7 also shows a vertical cross-sectional configuration for each pixel unit including the photoelectric conversion unit and the vertical transfer unit.

  In FIG. 7, a conventional solid-state imaging device 40 includes a photoelectric conversion unit 42 constituting a pixel unit as a light receiving unit that converts incident light into a signal charge on a semiconductor substrate 41, and a signal charge from the photoelectric conversion unit 42. A charge readout unit 43 for reading out a signal, a vertical charge transfer region 44 for transferring a signal charge read out by the charge readout unit 43 in the vertical direction, and an electrical separation from an adjacent pixel unit. And a channel stop 45.

  In the solid-state imaging device 40, a charge transfer electrode 47 is formed on the vertical charge transfer region 44 through a gate insulating film 46. By driving the charge transfer electrode 47 with a charge transfer drive pulse, The signal charges read from the photoelectric conversion unit 42 to the vertical charge transfer region 44 via the charge reading unit 43 are sequentially transferred in the vertical direction.

  Further, in the solid-state imaging device 40, first silicon oxide films 48a and 48b are formed on the charge transfer electrode 47 and the photoelectric conversion unit 42 by thermal oxidation treatment. A second silicon oxide film 51 and a light shielding film 52 are formed in this order so as to cover the entire surface of the substrate portion. In the second silicon oxide film 51 and the light shielding film 52, a light receiving opening 53 is formed so as to expose the top of each photoelectric conversion unit 42. The second silicon oxide film 51 is provided to insulate the interlayer wiring between the charge transfer electrode 47 and the light shielding film 52 thereabove. Further, an antireflection film 54 is provided on the entire surface of the substrate portion including the light receiving opening 53.

  Below, the manufacturing method of the conventional solid-state image sensor 40 proposed by patent document 2 is demonstrated.

  FIG. 8A to FIG. 8D are vertical cross-sectional views of relevant parts for explaining the respective steps of the method for manufacturing the solid-state imaging device 40 of FIG.

  First, as shown in FIG. 8A, the photoelectric conversion unit 42, the charge readout unit 43, the charge transfer region 44, and the channel stop unit 45 are formed in this order in the horizontal direction by impurity ion implantation processing on the semiconductor substrate 41. To do. A gate insulating film 46 made of an ONO film or the like is formed on the substrate portion. Further, a charge transfer electrode 47 is formed on the charge transfer region 44 through a gate insulating film 46. First silicon oxide films 28a and 28b are formed on these charge transfer electrodes 47 and photoelectric conversion portion 42 as a protective film for ion implantation by a thermal oxidation process.

  Next, as shown in the resist pattern forming step for forming the light shielding film in FIG. 8B, a second silicon oxide film 51 is deposited on the entire surface of the substrate portion with a film thickness of, for example, 40 nm to 50 nm by the LPCVD method. Subsequently, a light shielding film material 52a made of tungsten (W) or the like is deposited on the second silicon oxide film 51 with a film thickness of, for example, 100 nm to 150 nm. Using the photolithography technique, the resist pattern 50 is patterned so as to have a light receiving opening 50a on the light shielding film material 52a corresponding to the light receiving portion of each photoelectric conversion portion 42.

  Further, as shown in the light shielding film forming step of FIG. 8C, the second silicon oxide film 51 and the light shielding film material 52a corresponding to the openings 50a of the resist pattern 50 are etched away by a dry etching method. A light receiving opening 53 is formed in the silicon oxide film 51 and the light shielding film material 52a. Thereby, the light shielding film 52 opened on the light receiving portion of the photoelectric conversion unit 42 is formed in a predetermined pattern. Thereafter, the resist pattern 50 on the light shielding film 52 is removed.

  Subsequently, as shown in the antireflection film forming step in FIG. 8D, the antireflection film 54 is formed on the entire surface of the substrate including the light receiving opening 53 by, for example, 30 nm to 30 nm by the LPCVD method or the plasma CVD method. A silicon nitride film having a thickness of 50 nm is deposited.

  Although the illustration of subsequent steps is omitted, the solid-state imaging device 40 is manufactured by a manufacturing method according to a general technique and steps.

In the solid-state imaging device 40 having the conventional structure as proposed in Patent Document 2, the laminated structure of the film in the light receiving opening 53 on the photoelectric conversion unit 42 is the first silicon oxide film 48b and the antireflection film 54. It has a two-layer structure. The antireflection film 54 has low reflectivity, and can prevent the subject light collected by the microlens and incident from being reflected from the surface of the semiconductor substrate 41 (photoelectric conversion unit 42). Therefore, there is an advantage that the light receiving sensitivity in the photoelectric conversion unit 42 can be improved.
Japanese Patent Laid-Open No. 10-256518 JP 2001-352051 A

  In the conventional solid-state imaging device 20, as shown in FIG. 4, in order to improve the light receiving sensitivity to the photoelectric conversion unit 22, the first silicon oxide film 28b, the antireflection film 29, and the second on the photoelectric conversion unit 22. A laminated structure composed of the silicon oxide film 31 is provided, and reflection of subject light from the semiconductor substrate 21 (photoelectric conversion unit 22) is suppressed.

  However, the photoelectric conversion unit 22 and the light-shielding film 32 are caused by the thickness of the film in the laminated structure or the submergence of the light-shielding film 32 below the inner peripheral edge of the light-receiving opening 32a due to misalignment during patterning of the antireflection film 29. The gap becomes larger. For this reason, when a large amount of light is incident, there is a problem that light incident between the photoelectric conversion unit 22 and the light shielding film 32 is reflected between the light and leaks to the vertical charge transfer unit 24 side. was there. This phenomenon is called smear, which is an important item in the characteristics of the solid-state imaging device 20, and it is required to suppress this smear. Further, in the patterning of the antireflection film 29 by the photolithography technique, when the resist pattern 33 is formed on the bottom of the step between the adjacent charge transfer electrodes 27, the resist pattern 33 is formed by reflection from the side surface of the charge transfer electrode 27. There is also the problem of causing problems.

  In the conventional solid-state imaging device 40, although the problem of the conventional solid-state imaging device 20 is solved, a silicon nitride film is formed as an antireflection film 54 on the entire surface of the substrate portion including the light receiving opening 53. In this case, since the silicon nitride film does not have hydrogen permeability, if the entire surface of the substrate portion is covered with the silicon nitride film, the effect of hydrogen annealing on each photoelectric conversion portion 42 cannot be exhibited. There is a problem.

  The present invention solves the above-described conventional problems, improves the light receiving sensitivity characteristics by the antireflection film in the light receiving opening of the light shielding film without hindering the hydrogen annealing effect on each photoelectric conversion unit, and A solid-state imaging device capable of reducing and suppressing smear, a manufacturing method thereof, 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, and an image input camera An object of the present invention is to provide electronic information equipment such as a scanner, a facsimile, and a camera-equipped mobile phone.

  In the solid-state imaging device of the present invention, a photoelectric conversion unit for each pixel unit that converts incident light into a signal charge on a semiconductor substrate, and a charge transfer region that reads the signal charge from the photoelectric conversion unit and transfers the charge. In a solid-state imaging device which is provided adjacently and has a charge transfer electrode provided on the charge transfer region via a gate insulating film, on the photoelectric conversion unit and on the charge transfer electrode via a second insulating film A light-shielding film having a light-receiving opening that opens on the photoelectric conversion part is provided, and a patterned antireflection film is provided on the light-shielding film and the light-receiving opening. The above objective is achieved.

  Preferably, the antireflection film in the solid-state imaging device of the present invention is patterned into a predetermined pattern for hydrogen annealing.

  Further preferably, the antireflection film in the solid-state imaging device of the present invention covers an opening on at least a part of the charge transfer electrode from the light receiving opening on the photoelectric conversion part and covers a part of the charge transfer electrode. It is patterned to have

  Further preferably, the antireflection film in the solid-state imaging device of the present invention is patterned so as to open at least a part on the charge transfer electrode.

  Further preferably, the antireflection film in the solid-state imaging device of the present invention is a silicon nitride film.

  Further preferably, in the solid-state imaging device of the present invention, a first insulating film and the second insulating film formed on the photoelectric conversion unit are provided between the photoelectric conversion unit and the light shielding film. Yes.

  Further preferably, the first insulating film in the solid-state imaging device of the present invention is a silicon oxide film.

  Further preferably, in the solid-state imaging device of the present invention, a silicon oxide film is provided as the second insulating film between the charge transfer electrode and the light shielding film.

  Further preferably, in the solid-state imaging device of the present invention, a third insulating film is provided between the light shielding film and the antireflection film.

  Further preferably, the third insulating film in the solid-state imaging device of the present invention is a silicon oxide film.

  More preferably, the light receiving opening on the photoelectric conversion unit in the solid-state imaging device of the present invention is provided so as to penetrate at least the third insulating film and the light shielding film.

  Further preferably, in the solid-state imaging device according to the present invention, a film thickness of at least the first insulating film of the first insulating film and the second insulating film on the photoelectric conversion unit in the light receiving opening is 10 nm or more. 40 nm or less.

  The method for manufacturing a solid-state imaging device according to the present invention includes a photoelectric conversion unit for each pixel unit that converts incident light into a signal charge on a semiconductor substrate, and a charge transfer that reads the signal charge from the photoelectric conversion unit and transfers the charge. In the method for manufacturing a solid-state imaging device in which a region is formed adjacent to each other and a charge transfer electrode is formed on the charge transfer region via a gate insulating film, a second insulation is formed on the photoelectric conversion unit and the charge transfer electrode. A light-shielding film forming step of depositing a material to be a light-shielding film through the film and forming a light-receiving opening that opens on the photoelectric conversion portion in the material to be the light-shielding film; and a substrate portion after the light-shielding film forming step An antireflection film forming step of depositing a material to be an antireflection film thereon and patterning the material to be the antireflection film into a predetermined pattern to form an antireflection film. Achieved.

  Preferably, in the antireflection film forming step in the method for manufacturing a solid-state imaging device according to the present invention, the material to be the antireflection film is patterned into a predetermined pattern for performing hydrogen annealing in the subsequent step.

  Further preferably, the antireflection film forming step in the method for manufacturing a solid-state imaging device of the present invention covers a part of the charge transfer electrode from the light receiving opening on the photoelectric conversion unit, and the other part. The material to be the antireflection film is patterned so as to have an opening in at least a part of the film.

  Further preferably, in the antireflection film forming step in the method for manufacturing a solid-state imaging device of the present invention, the material to be the antireflection film is patterned so as to open at least a part on the charge transfer electrode.

  Further preferably, in the antireflection film forming step in the method for producing a solid-state imaging device of the present invention, a silicon nitride film is formed as the antireflection film by LPCVD or plasma CVD.

  Further preferably, as a pre-process of the light-shielding film forming step in the method for manufacturing a solid-state imaging device of the present invention, a silicon oxide film is formed as a first insulating film on the photoelectric conversion unit and the charge transfer electrode by a thermal oxidation process. A first insulating film forming step to be formed;

  Further preferably, in the method for manufacturing a solid-state imaging device of the present invention, a silicon oxide film is formed as the second insulating film on the first insulating film by LPCVD or plasma CVD.

  Further preferably, a third insulating film is formed on the light shielding film in order to prevent the light shielding film from being scraped during patterning of the antireflection film in the method for manufacturing a solid-state imaging device of the present invention.

  More preferably, a silicon oxide film is formed by LPCVD or plasma CVD as the third insulating film in the method for manufacturing a solid-state imaging device of the present invention.

  Further preferably, in the solid-state imaging device manufacturing method according to the present invention, in the light shielding film forming step, when the light receiving opening is formed, the openings are collectively formed in at least the third insulating film and the light shielding film. To do.

  Still preferably, in a method for manufacturing a solid-state imaging device according to the present invention, the light shielding film forming step includes the steps of forming the first insulating film and the second insulating film on the photoelectric conversion unit when forming the light receiving opening. At least the remaining film of the first insulating film is reduced to 10 nm or more and 40 nm or less.

  Furthermore, it is preferable that the method further includes a hydrogen annealing treatment step for performing a hydrogen annealing treatment of the photoelectric conversion portion after the antireflection film forming step in the method for manufacturing a solid-state imaging device of the present invention.

  The solid-state imaging device of the present invention is manufactured by the above-described method for manufacturing a solid-state imaging device of the present invention, and thereby the above object is achieved.

  An electronic information device according to the present invention uses the solid-state imaging device according to the present invention for an imaging unit, and thereby achieves the object.

  The operation of the present invention will be described below with the above configuration.

  In the present invention, a solid-state imaging device in which a photoelectric conversion portion and a charge transfer region are formed adjacent to each other on a semiconductor substrate, and a charge transfer electrode is selectively formed on the charge transfer region via a gate insulating film In this case, for example, a silicon oxide film as a first insulating film formed by, for example, a thermal oxidation process of an ion implantation prevention film on the charge transfer electrode and the photoelectric conversion unit, and insulation between the charge transfer electrode and the light shielding film For this purpose, an insulating film such as a silicon oxide film is formed as a second insulating film formed by the LPCVD method or the plasma CVD method, and a light shielding film is formed on the insulating film.

  In the vicinity of the light receiving opening on the photoelectric conversion unit, a first insulating film and a second insulating film are provided between the photoelectric conversion unit and the light-shielding film. Since no antireflection film is provided between them, the step can be reduced accordingly. In addition, when the light receiving opening is formed, it is not necessary to prevent the antireflection film from being exposed by etching, and the second insulating film can be made thinner. Accordingly, it is possible to further reduce smear by narrowing the interval between the photoelectric conversion unit and the light shielding film.

  A third insulating film is formed on the light shielding film by LPCVD or plasma CVD in order to prevent the light shielding film from being scraped during patterning of the antireflection film, and the third insulating film and the light shielding film are collectively processed. Thus, a light receiving opening is formed. At this time, by reducing the silicon oxide film on the photoelectric conversion portion to, for example, 10 nm or more and 40 nm or less, the interval between the light shielding film and the semiconductor substrate (photoelectric conversion portion) can be further reduced, and smear can be further suppressed. Become.

  A material to be an antireflection film such as a silicon nitride film is deposited on the substrate portion by LPCVD or plasma CVD, and the material to be the antireflection film is patterned with a predetermined pattern. This predetermined pattern is a predetermined pattern for hydrogen annealing. That is, the antireflection film is patterned so as to cover a part of the charge transfer electrode from the light receiving opening on the photoelectric conversion part and to have an opening in at least a part of the other part. Further, the antireflection film is patterned so as to open at least a part on the charge transfer electrode.

  Since the thinned silicon oxide film and the silicon nitride film as the antireflection film are provided on the photoelectric conversion unit, the subject light collected and incident by the microlens is incident on the semiconductor substrate (photoelectric conversion unit). It is possible to improve the light receiving sensitivity in the photoelectric conversion unit. In addition, a silicon nitride film as an antireflection film is not formed on the entire surface of the substrate including the light receiving opening as in the prior art, but the antireflection film is patterned to form an opening for each pixel. Therefore, the effect of hydrogen annealing on each photoelectric conversion unit can be sufficiently exerted through each patterned opening.

  As described above, according to the present invention, the antireflection film is not provided between the first insulating film and the second insulating film as in the prior art, but the patterned antireflection film is provided above the light shielding film. Therefore, the distance between the photoelectric conversion unit and the light shielding film is narrow in the vicinity of the light receiving opening on the photoelectric conversion unit with respect to the subject light incident on the photoelectric conversion unit through the antireflection film from the light receiving opening. By doing so, smear can be further suppressed. In addition, reflection on the surface of the semiconductor substrate (photoelectric conversion unit) can be suppressed by the antireflection film on the photoelectric conversion unit, and the light receiving sensitivity can be improved. Furthermore, since the opening is provided by patterning the antireflection film, the hydrogen annealing effect of each photoelectric conversion part can be sufficiently exhibited through each opening.

  Embodiments of a solid-state imaging device and a method for manufacturing the same according to the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a vertical cross-sectional view of a main part of a solid-state imaging device according to an embodiment of the present invention, and shows a vertical cross-sectional configuration for each pixel unit including a photoelectric conversion unit and a vertical transfer unit.

  In FIG. 1, a solid-state imaging device 10 according to the present embodiment includes a photoelectric conversion unit 2 constituting a pixel unit as a light receiving unit that converts incident light into a signal charge on a semiconductor substrate 1, and a photoelectric conversion unit 2. A charge readout unit 3 for reading out the signal charge, a vertical charge transfer region 4 for transferring the signal charge read out by the charge readout unit 3 in one vertical direction, and the adjacent pixel unit And a channel stop portion 5 for separation.

  In the solid-state imaging device 10, a charge transfer electrode 7 is formed on the vertical charge transfer region 4 via a gate insulating film 6. By driving the charge transfer electrode 7 with a charge transfer drive pulse, The signal charges read from the photoelectric conversion unit 2 to the vertical charge transfer region 4 via the charge reading unit 3 are sequentially transferred in the vertical direction.

  Further, in the solid-state imaging device 10, first silicon oxide films 8 a and 8 b as first insulating films are formed on the charge transfer electrode 7 and the photoelectric conversion unit 2. A second silicon oxide film 11 and a light shielding film 12 as a second insulating film are formed in this order so as to cover the substrate portion.

  A third silicon oxide film 13 as a third insulating film is formed on the light shielding film 12. In the second silicon oxide film 11, the light shielding film 12, and the third silicon silicon film 13, a light receiving opening 14 is formed so as to expose the light receiving portion of each photoelectric conversion unit 2.

  An antireflection film 15 is provided in a predetermined pattern on the third silicon oxide film 13. The antireflection film 15 is patterned with a predetermined pattern for hydrogen annealing in order to sufficiently exhibit the hydrogen annealing effect of the photoelectric conversion unit 2 in the subsequent process. For example, the antireflection film 15 is patterned so as to cover a part of the charge transfer electrode 7 from the light receiving opening 14 on the photoelectric conversion unit 2 and have an opening 15a in at least a part of the other part. ing. In this case, the antireflection film 15 is patterned so that at least a part (central part) on the charge transfer electrode 7 is opened by the opening 15a.

  The second silicon oxide film 11 is provided to insulate the interlayer wiring between the charge transfer electrode 7 and the light shielding film 12 thereabove. The third silicon oxide film 13 is provided on the light shielding film 12 in order to prevent the light shielding film 12 from being scraped when the antireflection film 15 is patterned in a later step.

  Below, the manufacturing method of the solid-state image sensor 10 of this embodiment is demonstrated in detail.

  2 (a) to 2 (c) and FIGS. 3 (d) to 3 (f) are main part longitudinal cross-sectional views for explaining each step of the manufacturing method of the solid-state imaging device 10 of FIG. is there.

  First, as shown in FIG. 2A, the semiconductor regions of the photoelectric conversion unit 2, the charge readout unit 3, the charge transfer region 4, and the channel stop unit 5 are laterally formed by impurity ion implantation processing on the semiconductor substrate 1, respectively. Form in this order in the direction. A gate insulating film 6 made of an ONO film or the like is formed on the substrate portion with a film thickness of, for example, about 50 nm to 70 nm. Further, a charge transfer electrode 7 made of a polysilicon film or the like with a film thickness of, for example, 150 nm to 250 nm is formed on the charge transfer region 4 via a gate insulating film 6 made of an ONO film or the like. First silicon oxide films 8a and 8b having a film thickness of, for example, 25 nm to 45 nm are formed as a protective film for ion implantation on the charge transfer electrode 7 and the photoelectric conversion unit 2 by a thermal oxidation process.

  Next, as shown in the resist pattern forming process for forming the light shielding film in FIG. 2B, the second silicon oxide film 11 is deposited on the substrate portion with a film thickness of, for example, 40 nm to 50 nm by the LPCVD method. Subsequently, a light shielding film material 12a made of tungsten (W) or the like is deposited on the second silicon oxide film 11 with a film thickness of, for example, 100 nm to 150 nm. Further, a third silicon oxide film 13 is deposited on the light shielding film material 12a with a film thickness of, for example, 40 nm to 50 nm by the LPCVD method. Using a photolithography technique, a resist pattern 16 having a light receiving opening 16a above each photoelectric conversion unit 2 is patterned.

  2C, the second silicon oxide film 11, the light shielding film material 12a and the third silicon oxide film 13 corresponding to the openings 16a of the resist pattern 16 are formed by dry etching. By etching away, a light receiving opening 14 is formed in the second silicon oxide film 11, the light shielding film material 12 a and the third silicon oxide film 13. At this time, the etching residual film of the silicon oxide film (first silicon oxide film 8b and second silicon oxide film 11) 14a on the photoelectric conversion unit 2 in the light receiving opening 14 has a thickness of, for example, 10 nm to 40 nm. (The film thickness is reduced from the second silicon oxide film 11 having a thickness of 40 nm to 50 nm and the first silicon oxide film 8b having a thickness of 25 nm to 45 nm). That is, in the light shielding film forming step, when the light receiving opening 14 is formed, the first silicon oxide film 8b as the first insulating film on the photoelectric conversion unit 2 and the second silicon oxide film as the second insulating film are formed. 11, the remaining film (silicon oxide film 14a) of at least the first silicon oxide film 8b is reduced from 10 nm to 40 nm. From the viewpoint of improving the light receiving sensitivity by preventing reflection, it is preferable to improve the antireflection effect by reducing the thickness of the silicon oxide film 14a, which is an etching residual film above the photoelectric conversion unit 2. In this manner, at least the second silicon oxide film 11, the light shielding film 12, and the third silicon oxide film 13 opened on the light receiving portion on the photoelectric conversion unit 2 are formed in a predetermined pattern. Thereafter, the resist pattern 16 on the third silicon oxide film 13 is removed.

  Thereafter, as shown in the antireflection film material deposition step in FIG. 3D, an LPCVD method or plasma CVD is performed as an antireflection film 15 on the entire surface of the substrate portion including each light receiving opening 14 for each photoelectric conversion portion 2. For example, a silicon nitride film (SiN film) is deposited with a film thickness of 30 nm to 50 nm by the method.

  Further, as shown in the resist pattern forming step for forming the antireflection film in FIG. 3E, the charge transfer electrode 7 is formed on the antireflection film 15 including the light receiving openings 14 by using a photolithography technique. A resist pattern 17 having an opening 17a that covers an upper part and opens another part (a central part on the charge transfer electrode 7) is patterned.

  Further, as shown in the antireflection film forming step in FIG. 3 (f), the portion that becomes the opening 15a of the antireflection film 15 corresponding to the opening 17a of the resist pattern 17 is etched away by a dry etching method to receive light. The antireflection film 15 having the opening 15a is patterned in a predetermined pattern so as to cover a part on the charge transfer electrode 7 from the opening 14 for use. This antireflection film 15 is patterned because the silicon nitride film does not have hydrogen permeability and the effect of hydrogen annealing cannot be exhibited if the entire surface of the substrate is covered. Thereafter, the resist pattern 17 on the antireflection film 15 is removed.

  Although the subsequent steps are not shown, the solid-state imaging device 10 of the present embodiment is manufactured by a manufacturing method according to a general technique and steps.

  The solid-state imaging device 10 of the present embodiment manufactured as described above has the first silicon oxide film 8a and the second silicon oxide between the photoelectric conversion unit 2 and the light shielding film 12 in the vicinity of the light receiving opening 14. Since an insulating film such as the film 11 is provided, and no antireflection film is provided between the first silicon oxide film and the second silicon oxide film as in the conventional solid-state imaging device 20 shown in FIG. The level difference can be reduced. Further, when the light receiving opening 14 is formed, it is not necessary to prevent the antireflection film from being exposed by etching, and the second silicon oxide film 11 can be made thinner. Accordingly, it is possible to reduce smear by narrowing the interval between the photoelectric conversion unit 2 and the light shielding film 12.

  Further, since the thinned silicon oxide film 14a and the silicon nitride film as the antireflection film 15 are provided on the photoelectric conversion unit 2, the subject light that is collected by the microlens and incident thereon is photoelectrically converted. Reflection on the surface of the unit 2 is suppressed, and the light receiving sensitivity in the photoelectric conversion unit 2 can be improved. Further, unlike the solid-state imaging device 40 shown in FIG. 7, the silicon nitride film is not formed on the entire surface of the substrate including the light receiving opening, but the antireflection film 15 is patterned to have the opening 15a. Therefore, the effect of hydrogen annealing on the photoelectric conversion unit 2 can be sufficiently exhibited.

  As described above, according to the present embodiment, the light shielding film 12 is formed on the photoelectric conversion unit 2 and the charge transfer electrode 7 via the first silicon oxide film 8a and the second silicon oxide film 11, and further thereon. Then, a third silicon oxide film 13 is formed, and a light receiving opening 14 is formed in the light shielding film 12 and the third silicon oxide film 13 at once. Since there is only a silicon oxide film 14a that is a remaining film after the formation of the light receiving opening 14 between the light shielding film 12 and the photoelectric conversion unit 2, the step is reduced by the amount of the antireflection film as compared with the conventional case. As a result, smear can be reduced. A material for forming the antireflection film 15 is deposited thereon to cover a part on the charge transfer electrode 7 from the light receiving opening 14 on the photoelectric conversion unit 2 and at least a part of the other part (here, Patterning is performed so as to have an opening 15a in the central portion on the charge transfer electrode 7). Reflection on the photoelectric conversion unit 2 is suppressed by the silicon oxide film 14a on the photoelectric conversion unit 2 and the silicon nitride film as the antireflection film 15, and the antireflection film 15 is patterned. The hydrogen annealing effect on the photoelectric conversion unit 2 can be sufficiently exhibited through 15a. Therefore, it is possible to improve the light receiving sensitivity characteristic in the light receiving opening 14 of the light shielding film 12 and to reduce and suppress smear without hindering the hydrogen annealing effect on the photoelectric conversion unit 2 as in the prior art.

  In the above-described embodiment, the antireflection film 15 covers a part on the charge transfer electrode 7 from the light receiving opening 14 on the photoelectric conversion unit 2 and opens at the center part on the other charge transfer electrode 7. Although it patterned so that it may have 15a, it is not restricted to this, It covers an upper part of the charge transfer electrode 7 from the opening 14 for light reception on the photoelectric conversion part 2, and has an opening part in at least one part of the other part It may be patterned like this. Further, not only the central portion on the charge transfer electrode 7 but also a pattern may be formed so that at least a part on the charge transfer electrode 7 is opened. In short, the antireflection film 15 only needs to be patterned into a predetermined pattern for hydrogen annealing, and the antireflection film patterned in a predetermined pattern may be provided on the light shielding film 12 and the light receiving opening 14. .

  Further, the solid-state imaging device of the present invention is not limited to the configuration of the solid-state imaging device 10 of the above-described embodiment, but on the photoelectric conversion unit 2 on the photoelectric conversion unit 2 and the charge transfer electrode 7 via the second insulating film. The light-shielding film 12 having the light-receiving opening 14 for opening the light-receiving opening 14 is provided, and the patterned anti-reflection film 15 may be provided on the light-shielding film 12 and the light-receiving opening 14. Accordingly, the light receiving sensitivity characteristic is improved by the antireflection film 15 in the light receiving opening 14 of the light shielding film 12 and the smear is reduced and suppressed without hindering the hydrogen annealing effect on each photoelectric conversion unit 2. be able to.

  Similarly, the manufacturing method of the solid-state imaging device of the present invention is not limited to the configuration of the manufacturing method of the solid-state imaging device 10 of the above embodiment, and the second insulating film is formed on the photoelectric conversion unit 2 and the charge transfer electrode 7. A light-shielding film forming step of depositing a material to be the light-shielding film 12 and forming a light-receiving opening 14 that opens on the photoelectric conversion unit 2 in the material to be the light-shielding film 12, and a substrate after the light-shielding film forming step An antireflection film forming step of depositing a material to be the antireflection film 15 on the portion and patterning the material to be the antireflection film 15 into a predetermined pattern to form the antireflection film 15 is sufficient. Accordingly, the light receiving sensitivity characteristic is improved by the antireflection film 15 in the light receiving opening 14 of the light shielding film 12 and the smear is reduced and suppressed without hindering the hydrogen annealing effect on each photoelectric conversion unit 2. be able to.

  Although not specifically described in the above embodiment, for example, a digital camera such as a digital video camera or a digital still camera using the solid-state imaging device 10 of the above embodiment as an imaging unit, an image input camera, a scanner, a facsimile, An electronic information apparatus having an image input device such as a camera-equipped mobile phone device will be described. The electronic information device according to the present invention is a memory such as a recording medium for recording data after performing predetermined signal processing for recording high-quality image data obtained by using the solid-state imaging device 10 according to the embodiment of the present invention as an imaging unit. A display means such as a liquid crystal display device for displaying the image data on a display screen such as a liquid crystal display screen after the image data is subjected to predetermined signal processing for display; and after the image data is subjected to predetermined signal processing for communication It has at least one of communication means such as a transmission / reception device for performing communication processing and image output means for printing (printing) and outputting (printing out) the image data.

  As mentioned above, although this invention has been illustrated using preferable embodiment of this invention, this invention should not be limited and limited to this embodiment. 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 of the present invention. Patents, patent applications, and documents cited herein should be incorporated by reference as if the contents themselves were specifically described in the present specification. Is understood.

  The present invention relates to a solid-state imaging device in which a plurality of light-receiving units that receive subject light and generate respective signal charges are two-dimensionally arranged, a manufacturing method thereof, and an imaging unit using the solid-state imaging device as an image input device. For example, in the field of digital information cameras such as digital video cameras and digital still cameras, and electronic information equipment such as image input cameras, scanners, facsimiles, and camera-equipped mobile phone devices, the first insulating film and the second film are used as in the past. Since the antireflection film is not provided between the insulating films, but a patterned antireflection film is provided above the light shielding film, it enters the photoelectric conversion section from the light receiving opening through the antireflection film. Smear is reduced by narrowing the distance between the photoelectric conversion unit and the light shielding film in the vicinity of the light receiving opening on the photoelectric conversion unit for incoming subject light. Ri can be suppressed. In addition, reflection on the surface of the semiconductor substrate (photoelectric conversion unit) can be suppressed by the antireflection film on the photoelectric conversion unit, and the light receiving sensitivity can be improved. Furthermore, since the opening is provided by patterning the antireflection film, the hydrogen annealing effect of each photoelectric conversion part can be sufficiently exhibited through each opening.

It is a principal part longitudinal cross-sectional view of the solid-state image sensor which concerns on embodiment of this invention. (A)-(c) is a principal part longitudinal cross-sectional view for demonstrating each process (the 1) of the manufacturing method of the solid-state image sensor of FIG. 1, respectively. (D)-(f) is a principal part longitudinal cross-sectional view for demonstrating each process (the 2) of the manufacturing method of the solid-state image sensor of FIG. 1, respectively. It is a principal part longitudinal cross-sectional view of the conventional solid-state image sensor currently disclosed by patent document 1. FIG. (A)-(c) is a principal part longitudinal cross-sectional view for demonstrating each process (the 1) of the manufacturing method of the solid-state image sensor of FIG. 4, respectively. (D)-(f) is a principal part longitudinal cross-sectional view for demonstrating each process (the 2) of the manufacturing method of the solid-state image sensor of FIG. 4, respectively. It is a principal part longitudinal cross-sectional view of the conventional solid-state image sensor currently disclosed by patent document 2. FIG. (A)-(d) is a principal part longitudinal cross-sectional view for demonstrating each process of the manufacturing method of the solid-state image sensor of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2 Photoelectric conversion part 3 Charge read-out part 4 Charge transfer area | region,
5 Channel stop section,
6 Gate insulation film (ONO film)
7 Charge transfer electrodes 8a, 8b First silicon oxide film (first insulating film)
10 Solid-state imaging device 11 Second silicon oxide film (second insulating film)
12 Light-shielding film 12a Material (material layer) to be light-shielding film
13 Third silicon oxide film (third insulating film)
14 Light receiving opening (light receiving area)
14a Silicon oxide film (residual film) left during etching of light receiving opening
DESCRIPTION OF SYMBOLS 15 Antireflection film 15a Opening part of antireflection film 16, 17 Resist pattern 16a Opening part of resist pattern 16 17a Opening part of resist pattern 17

Claims (26)

A photoelectric conversion unit for each pixel unit that converts incident light into signal charges and a charge transfer region that reads signal charges from the photoelectric conversion units and transfers charges are provided adjacent to each other on the semiconductor substrate. In the solid-state imaging device in which the charge transfer electrode is provided on the transfer region via the gate insulating film,
A light-shielding film having a light-receiving opening that opens on the photoelectric conversion part is provided on the photoelectric conversion part and the charge transfer electrode via a second insulating film, and the light-shielding film and the light-receiving opening part A solid-state imaging device having an antireflection film patterned thereon.   The solid-state imaging device according to claim 1, wherein the antireflection film is patterned into a predetermined pattern for hydrogen annealing.   2. The antireflection film is patterned so as to cover a part of the charge transfer electrode from a light receiving opening on the photoelectric conversion part and to have an opening in at least a part of the other part. Or the solid-state image sensor of 2.   The solid-state imaging device according to claim 1, wherein the antireflection film is patterned so as to open at least a part of the charge transfer electrode.   The solid-state imaging device according to claim 1, wherein the antireflection film is a silicon nitride film.   The solid-state imaging element according to claim 1, wherein a first insulating film and the second insulating film formed on the photoelectric conversion unit are provided between the photoelectric conversion unit and the light shielding film.   The solid-state imaging device according to claim 6, wherein the first insulating film is a silicon oxide film.   The solid-state imaging device according to claim 1, wherein a silicon oxide film is provided as the second insulating film between the charge transfer electrode and the light shielding film.   The solid-state imaging device according to claim 1, wherein a third insulating film is provided between the light shielding film and the antireflection film.   The solid-state imaging device according to claim 9, wherein the third insulating film is a silicon oxide film.   The solid-state imaging device according to claim 9, wherein the light receiving opening on the photoelectric conversion unit is provided so as to penetrate at least the third insulating film and the light shielding film.   7. The solid-state imaging device according to claim 6, wherein a film thickness of at least the first insulating film of the first insulating film and the second insulating film on the photoelectric conversion portion in the light receiving opening is not less than 10 nm and not more than 40 nm. . A photoelectric conversion unit for each pixel unit that converts incident light into signal charges and a charge transfer region that reads out signal charges from the photoelectric conversion units and transfers charges are formed adjacent to each other on the semiconductor substrate. In a method for manufacturing a solid-state imaging device in which a charge transfer electrode is formed on a transfer region via a gate insulating film,
A material that becomes a light shielding film is deposited on the photoelectric conversion portion and the charge transfer electrode via a second insulating film, and a light receiving opening that opens on the photoelectric conversion portion is formed in the material that becomes the light shielding film. A light shielding film forming step;
A solid having an antireflection film forming step of depositing a material to be an antireflection film on the substrate portion after the light shielding film forming step and patterning the material to be the antireflection film into a predetermined pattern to form an antireflection film; Manufacturing method of imaging device.   The solid-state imaging device manufacturing method according to claim 13, wherein in the antireflection film forming step, a material to be the antireflection film is patterned into a predetermined pattern for performing hydrogen annealing in a subsequent step.   The antireflection film forming step covers the antireflection so as to cover a part of the charge transfer electrode from the light receiving opening on the photoelectric conversion part and to have an opening in at least a part of the other part. The method for manufacturing a solid-state imaging device according to claim 13 or 14, wherein a material to be a film is patterned.   The method of manufacturing a solid-state imaging element according to claim 13, wherein in the antireflection film forming step, a material that becomes the antireflection film is patterned so as to open at least a part on the charge transfer electrode.   14. The method of manufacturing a solid-state imaging device according to claim 13, wherein in the antireflection film forming step, a silicon nitride film is formed as the antireflection film by an LPCVD method or a plasma CVD method.   14. The method according to claim 13, further comprising a first insulating film forming step of forming a silicon oxide film as a first insulating film on the photoelectric conversion unit and the charge transfer electrode by a thermal oxidation process as a pre-process of the light shielding film forming step. The manufacturing method of the solid-state image sensor of description.   19. The method for manufacturing a solid-state imaging element according to claim 18, wherein a silicon oxide film is formed as the second insulating film on the first insulating film by LPCVD or plasma CVD.   The method for manufacturing a solid-state imaging element according to claim 13, wherein a third insulating film is formed on the light shielding film in order to prevent the light shielding film from being scraped during patterning of the antireflection film.   21. The method of manufacturing a solid-state imaging element according to claim 20, wherein a silicon oxide film is formed as the third insulating film by an LPCVD method or a plasma CVD method.   The solid-state imaging device manufacturing method according to claim 20 or 21, wherein, in forming the light-receiving opening, the light-shielding film forming step collectively forms openings in at least the third insulating film and the light-shielding film. Method.   In the light shielding film forming step, when forming the light receiving opening, at least a remaining film of the first insulating film of the first insulating film and the second insulating film on the photoelectric conversion portion is 10 nm or more. The manufacturing method of the solid-state image sensor of Claim 18 or 19 reduced to 40 nm or less.   The method for manufacturing a solid-state imaging device according to claim 13, further comprising a hydrogen annealing treatment step of performing a hydrogen annealing treatment of the photoelectric conversion unit after the antireflection film forming step.   A solid-state imaging device manufactured by the method for manufacturing a solid-state imaging device according to claim 13.   The electronic information apparatus which used the solid-state image sensor in any one of Claims 1-12 for the imaging part.

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