JP2010080648A - Solid-state imaging device and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure sensitivity required for a pixel having low sensitivity while reliably forming a pixel having higher sensitivity than the pixel having low sensitivity. <P>SOLUTION: In this solid-state imaging device, a high sensitivity pixel (green pixel 11) which is sensitive to brightness, a low sensitivity pixel (blue pixel 14) which is less sensitive than the green pixel 11, and the like are cyclically and two-dimensionally disposed in accordance with a predetermined arrangement, and respective signal electric charges stored in each high sensitivity pixel and each low sensitivity pixel by a subject light are output as an image signal. A first flatting film 31 (embedding part 31a) made of a material having a high refractive index is formed on each light-receiving part in a plurality of high sensitivity pixels, and an interlayer dielectric made of a material having a lower refractive index than the first flatting film is formed on each light-receiving part in a plurality of low sensitivity pixels. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a solid-state imaging device and a manufacturing method thereof.

  In a general solid-state imaging device, incident light from a subject is photoelectrically converted by a photodiode formed in each pixel and accumulated as a signal charge in a plurality of pixels arranged two-dimensionally.

  On the other hand, in a pixel where the amount of incident light is so large that the signal charge overflows from the photodiode, the signal charge cannot increase while maintaining linearity as the amount of incident light increases. Therefore, the output signal based on this signal charge maintains linearity. Therefore, the luminance in the optical wavelength band cannot be resolved with respect to an incident light amount equal to or higher than the saturation level of the photodiode.

  In particular, in recent solid-state imaging devices in which the pixel size is reduced in order to reduce the chip size and increase the number of pixels, the size of the photodiode itself is also reduced. Some dynamic range has dropped.

  As a technique for expanding this dynamic range, a set of high-sensitivity pixels with high sensitivity and low-sensitivity pixels with low sensitivity are arranged two-dimensionally, and each photodiode of the high-sensitivity pixel and low-sensitivity pixel is used. A technique has been proposed in which a wide dynamic range is obtained by mixing each obtained charge with each set of pixels, and then converting and outputting it to a photographing signal (see, for example, Patent Document 1).

  Hereinafter, the conventional method described in Patent Document 1 will be specifically described with reference to the drawings.

  FIG. 6 shows a plan configuration of a main part of a conventional solid-state imaging device. As shown in FIG. 6, the conventional solid-state imaging device has a first photodiode 1 that is two-dimensionally arranged on a semiconductor substrate and has high sensitivity, and a low-sensitivity second photodiode 2 that has low sensitivity. A plurality of vertical transfer units 3 provided along the vertical array direction of the photodiodes 1 and 2, a horizontal transfer unit 4 provided adjacent to an end of the vertical transfer unit 3, and the horizontal transfer And an output amplifier section 5 provided at the end of the section 4.

  The signal charges photoelectrically converted by the photodiodes 1 and 2 are output by the output amplifier 5 through the vertical transfer unit 3 and the horizontal transfer unit 4.

  Here, the first photodiode 1 and the second photodiode 2 adjacent thereto are taken as one set, and the sizes of the photodiodes 1 and 2 or the opening areas of the respective light shielding films on the photodiodes 1 and 2 are made different. Thus, the sensitivity characteristics of the photodiodes 1 and 2 in each group are changed. The signal charges of the photodiodes 1 and 2 of each set are added and output at the time of reading.

According to such a configuration, the first photodiode 1 with high sensitivity is saturated immediately with the incidence of high-intensity light, but the second photodiode 2 with low sensitivity is not saturated immediately. Further, when the luminance of the incident light is low, the second photodiode 2 with low sensitivity can hardly be detected, but the first photodiode 1 with high sensitivity can be sufficiently detected. Therefore, according to the conventional solid-state imaging device, a wide dynamic range can be realized.
Japanese Patent Laid-Open No. 3-117281

  However, in recent solid-state imaging devices, the pixel size has been reduced, and in order to realize a high-sensitivity pixel in the prior art, it has become difficult to form a photodiode having a wide opening region or a wide storage region. ing. In particular, in a cell structure having one side of 2.0 μm or less, when the sensitivity is increased and decreased along with the reduction of the opening area, the extremely low sensitivity of the low-sensitivity pixel is low in S / N such as dark current and optical shot noise. This is a problem in terms of deteriorating the ratio, and is not an effective means for increasing the overall dynamic range.

  For this reason, it is necessary to form an antireflection film or the like on the upper part of the opening region even for pixels with low sensitivity. Therefore, in contrast to a low-sensitivity pixel structure in which such an antireflection film or the like is formed to increase sensitivity, a pixel with higher sensitivity requires a structure that can obtain higher sensitivity.

  In view of the above, it is an object of the present invention to reliably form a pixel having a higher sensitivity than a pixel having a low sensitivity while ensuring a necessary sensitivity for a pixel having a low sensitivity.

  In order to achieve the above object, the present invention provides a solid-state imaging device in which a high refractive index film is provided on a light receiving part of a pixel having high sensitivity and a low refractive index is provided on the light receiving part of a pixel having low sensitivity. A film is provided.

  Specifically, the solid-state imaging device according to the present invention includes a plurality of high-sensitivity pixels having high sensitivity to luminance and a plurality of low-sensitivity pixels having lower sensitivity than the high-sensitivity pixels periodically according to a predetermined arrangement. Targeting a solid-state imaging device that is two-dimensionally arranged and outputs, as an image signal, signal charges accumulated in each high-sensitivity pixel and each low-sensitivity pixel by subject light, each light-receiving unit in a plurality of high-sensitivity pixels A high refractive index film made of a material having a high refractive index and a low refractive index film made of a material having a refractive index lower than that of the high refractive index film formed on each light receiving portion in a plurality of low sensitivity pixels. It is characterized by having.

  According to the solid-state imaging device of the present invention, the high refractive index film is formed on the light receiving portion of the high sensitivity pixel, while the low refractive index film is formed on the light receiving portion of the low sensitivity pixel. For this reason, when the high-sensitivity pixels and the low-sensitivity pixels are alternately arranged adjacent to each other, it functions as an optical waveguide that collects incident light on the light-receiving portion of the high-sensitivity pixels. Can be increased. On the other hand, a low-sensitivity pixel having a low refractive index film can have a lower sensitivity than a high-sensitivity pixel without making the area different from that of the high-sensitivity pixel. Therefore, it is possible to reduce the color mixture that occurs due to the wide opening area of the high sensitivity pixel. Further, since the low-sensitivity pixel does not need to have a smaller area than the high-sensitivity pixel, the sensitivity of the low-sensitivity pixel does not become extremely low, and the S / N ratio is deteriorated due to dark current, light shot noise, and the like. There is nothing. Thereby, a wide dynamic range can be realized.

  In the solid-state imaging device of the present invention, it is preferable that the high refractive index film is surrounded by the low refractive index film to form an optical waveguide.

  In the solid-state imaging device of the present invention, each low-sensitivity pixel includes a first photoelectric conversion region formed on a semiconductor substrate, a first insulating film formed on the first photoelectric conversion region, and the first And a second insulating film having a refractive index higher than that of the first insulating film, and the low refractive index film is formed on the second insulating film. The high-sensitivity pixel is formed on the second photoelectric conversion region formed on the semiconductor substrate, the first insulating film formed on the second photoelectric conversion region, and the first insulating film. And a third insulating film made of the same material as the second insulating film, and the high refractive index film is preferably formed on the third insulating film.

  Thus, since the low refractive index film is formed on the second insulating film having a higher refractive index than the first insulating film in each low-sensitivity pixel, the second insulating film serves as a high reflection film. Since it functions, the reflection component of incident light can be reduced. For this reason, the sensitivity does not extremely decrease in the low-sensitivity pixel, and the S / N ratio does not deteriorate. In the high-sensitivity pixel, the high refractive index film is formed on the third insulating film made of the same material as the second insulating film. In the case where it is formed on the entire upper surface and then only the upper part of the light receiving portion of the high sensitivity pixel in the low refractive index film is selectively removed, the third insulating film is formed when the optical waveguide structure is formed. Since it can be used as an etching stopper, the manufacturing process can be simplified.

  In this case, the thickness of the third insulating film may be smaller than the thickness of the second insulating film.

  In this case, it is preferable that the third insulating film is formed in a region including the light receiving portion in each high sensitivity pixel.

  In this way, it is possible to obtain a margin when performing mask alignment for a region where the low refractive index film is etched.

  In this case, the third insulating film is preferably formed of the same material as the high refractive index film.

  In this case, since the refractive indexes of the third insulating film and the high refractive index film are equal to each other, it is possible to reduce the reflection component of incident light at the interface between the high refractive index film and the third insulating film. it can.

  In this case, the high refractive index film, the second insulating film, and the third insulating film are preferably made of silicon nitride or silicon nitride oxide.

  In this way, it is possible to reliably obtain the high refractive index film, the second insulating film as the high reflective film, and the third insulating film as the etching stopper according to the present invention.

  The solid-state imaging device of the present invention preferably further includes a color filter that is formed on each high-sensitivity pixel and on each low-sensitivity pixel and collects light having the same wavelength band from the subject light. .

  In this case, the color filter is preferably a color filter that transmits green.

  In this way, a wide dynamic range can be realized for a wavelength having the highest specific visibility for human eyes.

  The method for manufacturing a solid-state imaging device according to the present invention includes a step (a) of forming a plurality of photoelectric conversion regions each of which a first conductivity type region and a second conductivity type region are stacked on a semiconductor substrate, A step (b) of forming a low refractive index film on the entire surface of the photoelectric conversion region, a step (c) of selectively removing the low refractive index film from a part of the plurality of photoelectric conversion regions, And (d) forming a high refractive index film having a higher refractive index than the low refractive index film on a part of the photoelectric conversion region from which the low refractive index film has been removed.

  According to the method for manufacturing a solid-state imaging device of the present invention, the high refractive index film is selectively formed on the light receiving portion of the high sensitivity pixel, and the low refractive index film is formed on the light receiving portion of the low sensitivity pixel. The For this reason, when the high-sensitivity pixels and the low-sensitivity pixels are alternately arranged adjacent to each other, it functions as an optical waveguide that collects incident light on the light-receiving portion of the high-sensitivity pixels. Can be increased. On the other hand, a low-sensitivity pixel having a low refractive index film can have a lower sensitivity than a high-sensitivity pixel without making the area different from that of the high-sensitivity pixel. Therefore, it is possible to reduce the color mixture that occurs due to the wide opening area of the high sensitivity pixel. In addition, since it is not necessary to make the low-sensitivity pixel smaller than the high-sensitivity pixel, the sensitivity of the low-sensitivity pixel does not become extremely low, and the S / N ratio may be deteriorated due to dark current, light shot noise, or the like. Absent. Thereby, a wide dynamic range can be realized.

  The manufacturing method of the solid-state imaging device of the present invention further includes a step (e) of forming an insulating film on the semiconductor substrate between the step (a) and the step (b). The film preferably functions as an etching stopper for the low refractive index film when the low refractive index film is removed.

  In this case, the manufacturing process can be simplified because the step of providing the etching stopper can be omitted.

  In this case, the insulating film preferably has a higher refractive index than the low refractive index film.

  In this case, since the insulating film functions as a high reflection film in the low sensitivity pixel, the reflection component of incident light can be reduced. Therefore, the sensitivity is extremely lowered in the low sensitivity pixel and the S / N ratio is deteriorated. There is nothing to do.

  In this case, the insulating film is preferably made of silicon nitride or silicon nitride oxide.

  In the method for manufacturing a solid-state imaging device of the present invention, the high refractive index film is preferably made of silicon nitride or silicon nitride oxide.

  According to the solid-state imaging device and the manufacturing method thereof according to the present invention, it is possible to reliably form a pixel having a higher sensitivity than a pixel having a low sensitivity while ensuring a necessary sensitivity for a pixel having a low sensitivity. A wide dynamic range can be realized.

(One embodiment)
An embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 schematically shows a planar configuration of a CCD (Charge Coupled Device) type solid-state imaging device according to an embodiment of the present invention.

  As shown in FIG. 1, pixels 11, 12, 13, and 14 that are insulated and separated by an element isolation region are arranged on a main surface of a semiconductor substrate 10 so as to have, for example, a Bayer array.

  Here, reference numeral 11 represents a high-sensitivity pixel of green (G), reference numeral 12 represents a low-sensitivity pixel of green (G), reference numeral 13 represents a red (R) pixel, and reference numeral Reference numeral 14 denotes a blue (B) pixel.

  Specifically, the high-sensitivity pixel 11 has high sensitivity to luminance, that is, high sensitivity to the optical wavelength band, and the low-sensitivity pixel 12 has low sensitivity compared to the high-sensitivity pixel 11. That is, the sensitivity is lower than that of the high sensitivity pixel 11 with respect to the optical wavelength band. The red pixel 13 and the blue pixel 14 have the same configuration as the red low-sensitivity pixel 12.

  Note that the arrangement method of each pixel is not limited to the Bayer arrangement. In the case of the Bayer array, as in the present embodiment, in addition to the configuration in which the high-sensitivity pixel 11 and the low-sensitivity pixel 12 are respectively provided in two green pixels, red, green, and blue (RGB ) May be divided into high-sensitivity pixels and low-sensitivity pixels, respectively.

  In FIG. 1, the vertical transfer unit, the horizontal transfer unit, the output amplifier unit, and the like are not shown, but also in this embodiment, the vertical transfer unit, the horizontal transfer unit, and the same as the conventional example shown in FIG. The configuration may include an output amplifier unit, or another configuration. That is, the present invention is not limited to a CCD solid-state imaging device as a solid-state imaging device, but can be applied to a MIS (Metal Insulator Semiconductor) solid-state imaging device, and can also be applied to a back-illuminated imaging device. .

  FIG. 2 schematically shows a cross-sectional configuration taken along line II-II in FIG.

  First, the configuration of the blue pixel 14 having the same configuration as that of the green pixel 12 that is a low-sensitivity pixel will be described with reference to FIG.

As shown in FIG. 2, for example, a p ⁻⁻ type region 10a is formed on an upper portion of a semiconductor substrate 10 made of n ⁻ type silicon, and an n type region 10b is selectively formed on the p ⁻⁻ type region 10a. As a result, a first photodiode region 21L, which is a photoelectric conversion region, is formed. A p ⁺ type region 10 c is formed between the n type region 10 b and the surface of the semiconductor substrate 10.

  A first charge transfer region 23L is formed on one side of the first photodiode region 21L in the semiconductor substrate 10 via a first readout region 22L. The first photodiode region 21L, the first The blue pixel 14 is configured by the readout region 22L and the first charge transfer region 23L.

Here, the first read area 22L is ^{p -} becomes a part of the mold region 10a, a first charge transfer region 23L is ^{p -} -type region ^- type in the upper region 10a selectively formed p It consists of an n-type region thereon.

A gate insulating film 25 made of silicon oxide (SiO ₂ ) is formed on the main surface of the semiconductor substrate 10, and the gate insulating film 25 has a gate above the light receiving portion of the first photodiode region 21L. An antireflection film 26 made of silicon nitride (SiN) having a refractive index higher than that of the insulating film 25 is formed. The antireflection film 26 is not necessarily provided.

  Further, an electrode 27 made of, for example, polysilicon is formed on the upper portion of the gate insulating film 25 above the first charge transfer region 23L and the first readout region 22L. The electrode 27 has an upper surface and side surfaces covered with an insulating film 28 made of silicon oxide. On the insulating film 28, for example, tungsten (having an opening above the light receiving portion of the first photodiode region 21L). A light-shielding film 29 made of W) is formed.

  A transparent interlayer insulating film 30 made of, for example, BPSG (Boro-phospho Silicate Glass) doped with boron and phosphorus is formed on the first photodiode region 21L including the antireflection film 26 and on the light shielding film 29. Has been. On the interlayer insulating film 30, a first planarizing film 31 made of a material having a higher refractive index than the interlayer insulating film 30, for example, silicon nitride, for planarizing the unevenness of the surface of the interlayer insulating film 30 is provided. Is formed. Therefore, the interlayer insulating film 30 is a low refractive index film, while the first planarization film 31 is a high refractive index film.

  An in-layer convex lens 32 made of, for example, silicon nitride is formed on an upper portion of the light receiving portion of the first photodiode region 21L on the first planarizing film 31. Further, a second flattening film 33 made of, for example, NSG (Non-doped Silicate Glass) is formed on the in-layer convex lens 32 to flatten the unevenness caused by the in-layer convex lens 32.

  A color filter 34 is formed on the upper portion of the in-layer convex lens 32 on the second planarizing film 33. A blue color filter 34 is formed above the first photodiode region 21L in the blue pixel 14. A micro lens 35 is formed on the color filter 34. As described above, the in-layer convex lens 32 and the microlens 35 are configured at positions where incident light can be condensed on the first photodiode region 21L.

  Next, the configuration of the green pixel 11 which is a high sensitivity pixel will be described.

In the green pixel 11, an n-type region 10 b is formed above the p ⁻⁻ type region 10 a of the semiconductor substrate 10 with a channel stop region 24 made of a p ⁺ -type region interposed between the green pixel 11 and the blue pixel 14. ing. Also here, a p ⁺ -type region 10 c is formed between the n-type region 10 b and the surface of the semiconductor substrate 10, and the second photodiode as a photoelectric conversion region is formed by the p ⁻ -type region 10 a and the n-type region 10 b. Region 21H is formed.

  A charge transfer region 23H is formed in the region opposite to the blue pixel 14 with respect to the second photodiode region 21H in the semiconductor substrate 10 via the readout region 22H. The green pixel 11 is configured by the read region 22H and the second charge transfer region 23H.

  The difference from the blue pixel 14 that is not a high-sensitivity pixel is that, in the green pixel 11, an opening 30a is formed in the upper portion of the light receiving portion of the second photodiode region 21H in the interlayer insulating film 30, and the formed opening 30a has a buried portion 31a in which the first planarizing film 31 is buried. As described above, the opening 30a in the upper portion of the light receiving portion of the second photodiode region 21H in the interlayer insulating film 30 has the first refractive index higher than that of the silicon oxide constituting the interlayer insulating film 30. By embedding the planarizing film 31, the embedded part 31a on the light receiving part of the second photodiode region 21H in the first planarizing film 31 functions as an optical waveguide. A green color filter 34 is formed above the second photodiode region 21H in the green pixel 11.

  That is, in the present embodiment, incident light incident on the green pixel 11 is collected and diffracted by the microlens 35 and the in-layer convex lens 32. Furthermore, since the buried portion 31a on the light receiving portion of the second photodiode region 21H in the first planarization film 31 has a higher refractive index than the surrounding interlayer insulating film 30, the second photodiode region 21H has a higher refractive index. Incident light incident on the embedded portion 31a on the light receiving portion is confined in the embedded portion 31a. Since the light confinement effect by the embedded portion 31a is larger than the light diffraction effect, it greatly contributes to the improvement of the sensitivity of the light receiving portion of the second photodiode region 21H.

  Note that an etching stopper film 26 a made of silicon nitride, which is the same material as the antireflection film 26 constituting the blue pixel 14, is formed between the bottom of the buried portion 31 a and the gate insulating film 25 in the first planarization film 31. Is formed.

  Note that the etching stopper film 26a is not necessarily made of the same material as that of the antireflection film 26. For example, the same material as that of the interlayer insulating film 31 may be used. However, as will be described later, when the etching stopper film 26a is formed of the same material as the antireflection film 26, the step of forming the etching stopper film 26a independently can be omitted.

  The etching stopper film 26a is preferably formed in the light receiving portion of the second photodiode region 21H or a region including the light receiving portion.

  Hereinafter, a method for manufacturing a solid-state imaging device according to the present embodiment will be described with reference to the drawings.

  3A, FIG. 3B, FIG. 4A, FIG. 4B, and FIG. 5 show cross-sectional configurations in the order of steps of a method of manufacturing a solid-state imaging device according to an embodiment of the present invention. Yes.

First, as shown in FIG. 3A, a p ⁻ type region 10a having a junction depth of about 3 μm is formed on the semiconductor substrate 10 made of n ⁻ type silicon by ion implantation using a p type impurity. To do. Subsequently, as shown in FIG. 1, a plurality of n-type regions 10b are formed in an array on the p ⁻ -type region 10a by ion implantation using an n-type impurity. Subsequently, the first charge transfer region 23L and the second charge transfer region 23H in which the p ⁻ type region and the n type region are stacked are formed on one side of each column of each n type region 10b by ion implantation. Form. As a result, the first read region including the p ⁻⁻ type region 10a is formed between the first charge transfer region 23L and the n-type region 10b and between the second charge transfer region 23H and the n-type region 10b. 22L and the second readout region 22H are formed. Further, a channel stop region 24 made of a p ⁺ -type region is formed between the other side of each n-type region 10b and each readout region 22L, 22H by ion implantation. Further, ap ⁺ type region 10 c is formed between each n type region 10 b and the surface of the semiconductor substrate 10. Thereby, in the blue pixel 14, the first photodiode region 21L is formed by the p ⁻⁻ type region 10a and the n type region 10b, and in the green pixel 11, the p ⁻⁻ type region 10a and the n type region are formed. A second photodiode region 21H is formed by the region 10b.

  Next, as shown in FIG. 3B, a gate insulating film 25 made of silicon oxide having a thickness of 40 nm is formed on the main surface of the semiconductor substrate 10 by a thermal oxidation method or the like. Subsequently, for example, a silicon nitride film having a refractive index higher than that of silicon oxide constituting the gate insulating film 25 is formed on the entire surface of the gate insulating film 25 by chemical vapor deposition (CVD). Subsequently, the antireflection film 26 is formed from the silicon nitride film by patterning the silicon nitride film so as to remain in the regions including the light receiving portions of the photodiode regions 21L and 21H by lithography and etching. After that, for example, polysilicon is formed on the upper portion of the first charge transfer region 23L and the first read region 22L and the upper portion of the second charge transfer region 23H and the second read region 22H on the gate insulating film 25. Each of the electrodes 27 extending in the column direction is formed. Thereafter, an insulating film 28 made of silicon oxide is formed so as to cover each formed electrode 27, and subsequently, made of tungsten so as to cover the antireflection film 26 and the insulating film 28 by CVD or sputtering. A light shielding film 29 is formed. Further, the formed light shielding film 29 is selectively etched and removed so that the antireflection film 26 on the photodiode regions 21L and 21H is exposed.

  Next, as shown in FIG. 4A, an interlayer insulating film made of BPSG with a thickness of 400 nm so as to cover the light shielding film 29 and the antireflection film 26 on the entire surface of the semiconductor substrate 10 by CVD. Low refractive index film) 30 is formed. Thereafter, the interlayer insulating film 30 is heat treated to reflow the interlayer insulating film 30. As a result, the surface of the interlayer insulating film 30 has an uneven shape corresponding to the step formed by the electrode 27 and the light shielding film 29, and has an in-layer concave lens shape in which a recess is formed on each of the photodiode regions 21L and 21H. .

  Next, as shown in FIG. 4B, a resist film 40 is formed on the interlayer insulating film 30 by lithography, and then the upper portion of the light receiving portion of the second photodiode region 21H is exposed. An opening pattern is formed. Subsequently, using the resist film 40 with the opening pattern as a mask, the interlayer insulating film 30 is subjected to anisotropic etching to form an opening 30 a reaching the antireflection film 26 in the interlayer insulating film 30. At this time, in the green pixel 11 which is a high sensitivity pixel, the antireflection film 26 functions as an etching stopper film 26a. At this time, the upper portion of the etching stopper film 26a is etched and the film thickness thereof becomes thinner than that of the original antireflection film 26. As described above, in the present embodiment, the antireflection film 26 used in the blue pixel 14 that is not a high-sensitivity pixel is used as the etching stopper film in the green pixel 11 that is a high-sensitivity pixel in which it is not particularly necessary to provide the antireflection film 26. Since it is used as 26a, the step of forming the etching stopper film 26a can be omitted, so that the manufacturing process can be simplified.

  Next, as shown in FIG. 5, a first planarizing film (high refractive index film) 31 made of silicon nitride and having a higher refractive index than the interlayer insulating film 30 is formed on the interlayer insulating film 30 by a CVD method. The openings 30a formed in the interlayer insulating film 30 are embedded. As a result, in the green pixel 11 that is a high-sensitivity pixel, the embedded portion 31a in the opening 30a in the first planarization film 31 is formed as an optical waveguide structure for incident light, while blue that is not a high-sensitivity pixel. In the pixel 14 and the green pixel 12 which is the low sensitivity pixel shown in FIG. 1, an in-layer concave lens shape is formed. Subsequently, the surface of the formed first planarization film 31 is planarized by reflow or chemical mechanical polishing (CMP). In this embodiment, silicon nitride (SiN) is used for the antireflection film 26, the etching stopper film 26a, and the first planarization film 31, but silicon nitride oxide (SiON) may be used.

  Subsequently, a silicon nitride film is formed on the first planarization film 31 by the CVD method, and the regions above the photodiode regions 21L and 21H in the silicon nitride film are formed by the lithography method and the etching method, respectively. An in-layer convex lens 32 having a convex cross section is formed from the silicon nitride film. Here, as a method of forming a plurality of in-layer convex lenses 32 having a convex cross section from a silicon nitride film having a flat surface, for example, after forming a resist film in an in-layer convex lens forming region on the silicon nitride film, the resist The film can be formed by reflowing to form a convex cross section and performing etch back of the silicon nitride film using a resist film having a convex cross section.

  Subsequently, a second planarizing film 33 made of NSG is formed on the first planarizing film 31 including the in-layer convex lens 32 by CVD, and then the second planarizing film 32 formed is formed. Flatten the surface.

  Subsequently, a color filter 34 made of an organic material and transmitting light corresponding to pixels of each color is formed in a region above the in-layer convex lens 32 in the second planarizing film 33, and then each color filter 34. A microlens 35 made of a transparent organic material is formed thereon.

  With the above manufacturing method, in the green pixel 11 which is a high-sensitivity pixel, the optical waveguide including the embedded portion 31a of the first planarization film 31 only in the interlayer insulating film 30 above the second photodiode region 21H. A solid-state imaging device of the present invention in which the structure is formed and the plane areas of the low-sensitivity pixels and the high-sensitivity pixels are equal can be obtained.

  Note that the solid-state imaging device and the method for manufacturing the same according to the present invention are not limited to the above-described embodiment. For example, the in-layer concave lens shape by the first planarization film 31 using the surface shape of the interlayer insulating film 30 and Various configurations can be adopted without departing from the gist of the present invention, such as a configuration in which the in-layer convex lens 32 is omitted.

  The solid-state imaging device and the manufacturing method thereof according to the present invention can reliably form pixels having higher sensitivity than pixels having low sensitivity while ensuring necessary sensitivity for pixels having low sensitivity. It is useful as a solid-state imaging device for a mobile phone or a medical camera, a manufacturing method thereof, and the like.

1 is a schematic plan view showing a solid-state imaging device according to an embodiment of the present invention. It is sectional drawing in the II-II line of FIG. (A) And (b) is sectional drawing of the order of a process which shows the manufacturing method of the solid-state imaging device which concerns on one Embodiment of this invention. (A) And (b) is sectional drawing of the order of a process which shows the manufacturing method of the solid-state imaging device which concerns on one Embodiment of this invention. It is sectional drawing which shows 1 process of the manufacturing method of the solid-state imaging device which concerns on one Embodiment of this invention. It is a typical top view which shows the conventional solid-state imaging device.

Explanation of symbols

10 Semiconductor substrate 10a p ⁻⁻ type region 10b n type region 10c p ⁺ type region 11 Green pixel (high sensitivity pixel)
12 Green pixels (low sensitivity pixels)
13 Red pixel 14 Blue pixel 21L First photodiode region (first photoelectric conversion region)
21H Second photodiode region (second photoelectric conversion region)
22L First read region 22H Second read region 23L First charge transfer region 23H Second charge transfer region 24 Channel stop region 25 Gate insulating film 26 Antireflection film 26a Etching stopper film 27 Electrode 28 Insulating film 29 Light shielding film 30 Interlayer insulation film (low refractive index film)
30a Opening 31 First planarization film (high refractive index film)
31a Embedded portion 32 In-layer convex lens 33 Second planarizing film 34 Color filter 35 Micro lens 40 Resist film

Claims (14)

A plurality of high-sensitivity pixels having high sensitivity to luminance and a plurality of low-sensitivity pixels having lower sensitivity than the high-sensitivity pixels are periodically and two-dimensionally arranged according to a predetermined arrangement, A solid-state imaging device that outputs each of signal charges accumulated in a sensitivity pixel and each of the low-sensitivity pixels as an image signal,
A high refractive index film formed on each light receiving portion in the plurality of high sensitivity pixels and made of a material having a high refractive index;
A solid-state imaging device comprising: a low refractive index film formed on each light receiving portion in the plurality of low sensitivity pixels and made of a material having a refractive index lower than that of the high refractive index film.   The solid-state imaging device according to claim 1, wherein the high refractive index film is surrounded by the low refractive index film to form an optical waveguide. Each of the low-sensitivity pixels includes a first photoelectric conversion region formed on a semiconductor substrate, a first insulating film formed on the first photoelectric conversion region, and on the first insulating film. And a second insulating film having a refractive index higher than that of the first insulating film, and the low refractive index film is formed on the second insulating film,
Each of the high-sensitivity pixels includes a second photoelectric conversion region formed on the semiconductor substrate, the first insulating film formed on the second photoelectric conversion region, and the first insulating film. And a third insulating film made of the same material as the second insulating film, and the high refractive index film is formed on the third insulating film. The solid-state imaging device according to claim 1 or 2.   The solid-state imaging device according to claim 3, wherein a film thickness of the third insulating film is smaller than a film thickness of the second insulating film.   5. The solid-state imaging device according to claim 3, wherein the third insulating film is formed in a region including the light receiving portion in each of the high sensitivity pixels.   The solid-state imaging device according to claim 3, wherein the third insulating film is made of the same material as that of the high refractive index film.   The solid-state imaging device according to claim 3, wherein the high refractive index film, the second insulating film, and the third insulating film are made of silicon nitride or silicon nitride oxide. .   2. A color filter that is formed on each of the high-sensitivity pixels and on each of the low-sensitivity pixels and collects light having the same wavelength band of the subject light. The solid-state imaging device of any one of -7.   The solid-state imaging device according to claim 8, wherein the color filter is a color filter that transmits green. A step (a) of forming a plurality of photoelectric conversion regions each of which a first conductivity type region and a second conductivity type region are stacked on a semiconductor substrate;
A step (b) of forming a low refractive index film on the entire surface of the plurality of photoelectric conversion regions;
A step (c) of selectively removing the low refractive index film with respect to a part of the plurality of photoelectric conversion regions;
And (d) forming a high refractive index film having a higher refractive index than the low refractive index film on the partial photoelectric conversion region from which the low refractive index film has been removed. A method for manufacturing a solid-state imaging device. Between the step (a) and the step (b),
A step (e) of forming an insulating film on the semiconductor substrate;
The method of manufacturing a solid-state imaging device according to claim 10, wherein, in the step (c), the insulating film functions as an etching stopper for the low refractive index film when the low refractive index film is removed. .   The method for manufacturing a solid-state imaging device according to claim 11, wherein the insulating film has a refractive index higher than that of the low refractive index film.   The method for manufacturing a solid-state imaging device according to claim 11, wherein the insulating film is made of silicon nitride or silicon nitride oxide.   The method for manufacturing a solid-state imaging device according to claim 10, wherein the high refractive index film is made of silicon nitride or silicon nitride oxide.

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