WO2017130682A1 - Solid-state image capture device - Google Patents

Solid-state image capture device Download PDF

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WO2017130682A1
WO2017130682A1 PCT/JP2017/000435 JP2017000435W WO2017130682A1 WO 2017130682 A1 WO2017130682 A1 WO 2017130682A1 JP 2017000435 W JP2017000435 W JP 2017000435W WO 2017130682 A1 WO2017130682 A1 WO 2017130682A1
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solid
microlens
imaging device
state imaging
substrate
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PCT/JP2017/000435
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French (fr)
Japanese (ja)
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横山　敏史
嘉昭 西
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パナソニック・タワージャズセミコンダクター株式会社
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B3/00—Simple or compound lenses
    • H01L27/14627—
    • H01L27/14—

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  • the present invention relates to a solid-state imaging device, and more particularly to a technique for suppressing the occurrence of flare.
  • Patent Document 1 flare is suppressed by a structure in which a light shielding film is inserted between pixels.
  • Patent Document 2 a technique of forming an antireflection film on the surface of a microlens is also known.
  • An object of the present invention is to suppress the occurrence of flare in a solid-state imaging device by devising the outer shape of a microlens.
  • the present invention provides a solid-state imaging device including a substrate having a plurality of pixels formed on the main surface and a plurality of microlenses for guiding incident light to corresponding pixels among the plurality of pixels.
  • each of the plurality of microlenses does not have an outer surface whose angle with the main surface of the substrate is 20 ° or more and 40 ° or less.
  • the present invention even if a glass plate is arranged in front of a plurality of microlenses, the light reflected by the surface of the outer surface of the microlens whose angle with the main surface of the substrate is smaller than 20 °. Even if the light is re-reflected, the light does not enter the microlenses at a distant position, and enters the adjacent microlenses in a very narrow range. Further, the light reflected by the surface of the outer surface of the microlens whose angle with the main surface of the substrate is larger than 40 ° is incident on the nearest adjacent microlens. Therefore, flare caused by reflection on the outer surface of the microlens and entering the microlens at a distant position is suppressed by the present invention.
  • each of the plurality of microlenses has a first outer surface located on the apex side and a second outer surface located on the base side, and an angle formed between the first outer surface and the main surface of the substrate is The angle between the second outer surface and the main surface of the substrate is smaller than 20 ° and larger than 40 °.
  • each of the plurality of microlenses has an antireflection film formed on the surface.
  • flare generation in the solid-state imaging device can be suppressed by devising the outer shape of the microlens.
  • FIG. 1 is a cross-sectional view of a solid-state imaging device according to a first embodiment of the present invention.
  • FIG. 4 is a plan view of the microlens in FIG. 3.
  • FIG. 5 is a VV cross-sectional view of FIG. 4. It is a top view of the micro lens which shows the modification of FIG.
  • FIG. 7 is a sectional view taken along line VII-VII in FIG. 6. It is sectional drawing of the solid-state imaging device which concerns on the 2nd Embodiment of this invention.
  • FIG. 1 is a diagram showing the occurrence of flare in a conventional solid-state imaging device, and shows a photograph taken of a high-intensity light source in a dark room.
  • flares are radially generated around the image of the high-intensity light source.
  • magenta flare is a big problem because it is easily visible.
  • FIG. 2 is a cross-sectional view of a conventional solid-state imaging device.
  • the solid-state imaging device of FIG. 2 includes a semiconductor layer 7 provided on the main surface of a silicon substrate (not shown).
  • the semiconductor layer 7 has a plurality of photodiodes (not shown) each constituting a pixel.
  • an RGB color filter 6 is formed on a semiconductor layer 7, and a microlens 8 for each pixel is provided thereon via a planarizing film 9, which is sealed with a sealing glass 12. Further, an IR cut filter 13 is provided.
  • the shape of the conventional microlens 8 is generally a hemispherical shape as shown in FIG.
  • FIG. 2 is also a diagram for explaining the cause of flare in a conventional solid-state imaging device.
  • Incident light that has passed through the IR cut filter 13 and the seal glass 12 reaches the microlens 8, most of which is condensed by the microlens 8, passes through the color filter 6, and enters the pixels in the semiconductor layer 7. .
  • the light reflected on the surface of the microlens 8 (reflectance is about 4.5%) proceeds obliquely, and part of the light is reflected on the outer surface of the seal glass 12, while the other part is the inner surface of the IR cut filter 13. Reflected by.
  • FIG. 1 is also a diagram for explaining the cause of flare in a conventional solid-state imaging device.
  • the reflection angle on the outer surface of the seal glass 12 is ⁇ 1
  • the reflection angle on the inner surface of the IR cut filter 13 is ⁇ 2.
  • the light reflected by the seal glass 12 and the IR cut filter 13 is incident on a pixel at a distant position. This is the cause of flare.
  • the inventor of the present application analyzes the flare generation state of FIG. 1, and the reflected light in the range where the angles ⁇ 1 and ⁇ 2 in FIG. 2 are 40 ° or more and 80 ° or less is stray light causing flare, It has been found that flare generation can be suppressed by eliminating the reflected light on the microlens surface in this range.
  • the present invention devises the outer shape of the microlens based on this knowledge.
  • FIG. 3 is a cross-sectional view of the solid-state imaging device according to the first embodiment of the present invention.
  • the solid-state imaging device of FIG. 3 forms a gate 3, a wiring layer 4, and a buried layer 5 on a main surface of a silicon substrate 1 in addition to a plurality of photodiodes 2 each constituting a pixel.
  • a plurality of photodiodes 2 each constituting a pixel.
  • the silicon substrate 1 is a 35 mm full size standard substrate, and the size of each pixel viewed from above is 6 ⁇ m ⁇ 6 ⁇ m.
  • Each of the plurality of microlenses 14 is formed in a convex shape having a pentagonal cross section so as to guide incident light to the corresponding pixel, and is located on the first outer surface 21 located on the apex side and on the base side. It has only two outer surfaces with the second outer surface 22.
  • the solid-state imaging device of FIG. 3 has the same structure and size as the conventional solid-state imaging device shown in FIG. 2 except that the external shape of the microlens is different. In FIG. The illustration is omitted.
  • silicon nitride which is a high refractive index material is used. Since silicon nitride, which is a high refractive index material, can confine light and functions like an optical waveguide, an extremely sensitive device is realized.
  • the electrical signal of each pixel obtained by photoelectric conversion by the photodiode 2 is read by the gate 3 formed on the silicon substrate 1.
  • FIG. 4 is a plan view of the microlens 14 in FIG. 3, and FIG. 5 is a VV cross-sectional view along a cut surface extending in a diagonal direction in FIG.
  • the microlens 14 when viewed from above, has a substantially rectangular outer shape corresponding to the planar shape of the photodiode 2 constituting the pixel.
  • the first outer surface 21 is in the form of a conical side.
  • reference numeral 20 represents a reference plane parallel to the main surface of the silicon substrate 1. If the angle formed by the first outer surface 21 and the reference surface 20 is ⁇ , ⁇ ⁇ 20 °. If the angle formed between the second outer surface 22 and the reference surface 20 is ⁇ , ⁇ > 40 °. Since the outer surface of the microlens 14 is only the first and second outer surfaces 21 and 22, the microlens 14 does not have an outer surface whose angle with the reference surface 20 is 20 ° or more and 40 ° or less.
  • the shape of the microlens 14 shown in FIGS. 4 and 5 is realized, for example, by performing a lithography process on a resist that is a lens material.
  • the mask to be used is subjected to processing different from normal patterning and is developed with gradation. Since the microlens 14 is formed only by lithography and development processing, the cost is low. Further, sensitivity and incident angle characteristics equivalent to those of a conventional hemispherical microlens can be obtained.
  • FIG. 6 is a plan view of a microlens 14 showing a modification of FIG. 4, and FIG. 7 is a sectional view taken along line VII-VII in FIG.
  • the microlens 14 shown in FIGS. 6 and 7 includes a third outer surface that fills the diagonal gap of the pixels in addition to the first outer surface 21 located on the apex side and the second outer surface 22 located on the base side. It has an outer surface 23.
  • the angle formed between the first outer surface 21 and the substrate main surface is smaller than 20 °
  • the angle formed between the second outer surface 22 and the substrate main surface is larger than 40 °
  • the third outer surface is smaller than 20 °.
  • the microlens 14 can have various outer shapes on condition that the angle formed with the main surface of the substrate does not have an outer surface that is 20 ° or more and 40 ° or less.
  • at least one of the plurality of outer surfaces may have a curved outer shape in cross section.
  • the portion of the first outer surface located on the apex side among the plurality of outer surfaces may be semicircular in cross section.
  • FIG. 8 is a cross-sectional view of a solid-state imaging device according to the second embodiment of the present invention.
  • the antireflection film 15 is formed by depositing SiO 2 with a thickness of 95 nm by CVD.
  • the size of the microlens 14 is prepared in advance in consideration of the amount of film formation.
  • the reflectance of the surface of the microlens 14 is reduced from 4.5% to 2.9%, for example, and flare can be more reliably suppressed. Further, since the antireflection film 15 is made of an inorganic material, the surface can be easily cleaned, and it becomes very easy to handle in the subsequent assembly process.
  • the present invention is useful because it can realize a solid-state imaging device capable of outputting an image in which the occurrence of flare is suppressed.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Solid State Image Pick-Up Elements (AREA)
  • Transforming Light Signals Into Electric Signals (AREA)

Abstract

On a substrate (1) comprising a plurality of photodiodes (2) respectively formed as pixels on a major surface, a plurality of microlenses (14) for respectively guiding incident light to corresponding pixels are provided. Each of the plurality of microlenses (14) includes a first outer surface (21) positioned on an apex side, and a second outer surface (22) positioned on a proximal side. In order to suppress the generation of a flare, the first outer surface (21) and the major surface of the substrate (1) form an angle smaller than 20°, and the second outer surface (22) and the major surface of the substrate (1) form an angle greater than 40°.

Description

固体撮像装置Solid-state imaging device
　本発明は、固体撮像装置に関し、特にフレアの発生を抑制する技術に関するものである。 The present invention relates to a solid-state imaging device, and more particularly to a technique for suppressing the occurrence of flare.
　近年、チップサイズの大きなイメージセンサを適用した高級カメラの開発が盛んとなっている。ところが、センササイズが大きくなることで迷光がセンサへ再入射しやすくなり、フレアとして撮像されるケースが発生しやすくなっている。特に夜間に高輝度光源を撮影した際はフレアが顕著に認識され、画質の低下が大きくなる。 In recent years, development of high-end cameras using image sensors with a large chip size has become active. However, as the sensor size increases, stray light easily re-enters the sensor, and a case where the image is captured as flare is likely to occur. In particular, when a high-intensity light source is photographed at night, flare is recognized remarkably, and image quality is greatly deteriorated.
　特許文献１では、画素間に遮光膜を挿入した構造でフレアを抑制している。特許文献２のように、マイクロレンズの表面に反射防止膜を形成する技術も知られている。 In Patent Document 1, flare is suppressed by a structure in which a light shielding film is inserted between pixels. As in Patent Document 2, a technique of forming an antireflection film on the surface of a microlens is also known.
特開２０１０－１８６８１８号公報JP 2010-186818 A 特開２００２－２８０５３３号公報JP 2002-280533 A
　しかしながら、特許文献１の構造では、遮光膜に当たらない光がフレアの原因となる混色成分として残る。また、特許文献２の技術では、反射防止膜で反射光を低減してもフレアが薄くなるだけで、フレアを完全には除去できない。 However, in the structure of Patent Document 1, light that does not strike the light shielding film remains as a color mixture component that causes flare. Further, in the technique of Patent Document 2, even if the reflected light is reduced by the antireflection film, the flare is only thinned and the flare cannot be completely removed.
　本発明の目的は、マイクロレンズの外形を工夫することにより、固体撮像装置におけるフレアの発生を抑制することにある。 An object of the present invention is to suppress the occurrence of flare in a solid-state imaging device by devising the outer shape of a microlens.
　上記課題に対し、本発明は、主面に複数の画素が形成されてなる基板と、各々入射光を複数の画素のうちの対応する画素へ導くための複数のマイクロレンズとを備えた固体撮像装置において、複数のマイクロレンズの各々は、基板の主面となす角度が２０°以上かつ４０°以下となる外面を有しないこととしたものである。 In order to solve the above problems, the present invention provides a solid-state imaging device including a substrate having a plurality of pixels formed on the main surface and a plurality of microlenses for guiding incident light to corresponding pixels among the plurality of pixels. In the apparatus, each of the plurality of microlenses does not have an outer surface whose angle with the main surface of the substrate is 20 ° or more and 40 ° or less.
　本発明によれば、複数のマイクロレンズの前方にガラス板が配置されても、マイクロレンズの外面のうち基板の主面となす角度が２０°より小である面で反射した光が当該ガラス板で再反射しても、離れた位置のマイクロレンズへ入射することはなく、極めて狭い範囲の隣接マイクロレンズへ入射することになる。また、マイクロレンズの外面のうち基板の主面となす角度が４０°より大である面で反射した光は、直近の隣接マイクロレンズへ入射することになる。したがって、マイクロレンズの外面で反射して、離れた位置のマイクロレンズへ入射することにより生じるフレアは、本発明により抑制される。 According to the present invention, even if a glass plate is arranged in front of a plurality of microlenses, the light reflected by the surface of the outer surface of the microlens whose angle with the main surface of the substrate is smaller than 20 °. Even if the light is re-reflected, the light does not enter the microlenses at a distant position, and enters the adjacent microlenses in a very narrow range. Further, the light reflected by the surface of the outer surface of the microlens whose angle with the main surface of the substrate is larger than 40 ° is incident on the nearest adjacent microlens. Therefore, flare caused by reflection on the outer surface of the microlens and entering the microlens at a distant position is suppressed by the present invention.
　好ましくは、複数のマイクロレンズの各々は、頂点側に位置する第１の外面と、基部側に位置する第２の外面とを有し、第１の外面と基板の主面とのなす角度は２０°より小であり、かつ第２の外面と基板の主面とのなす角度は４０°より大であることとする。 Preferably, each of the plurality of microlenses has a first outer surface located on the apex side and a second outer surface located on the base side, and an angle formed between the first outer surface and the main surface of the substrate is The angle between the second outer surface and the main surface of the substrate is smaller than 20 ° and larger than 40 °.
　更に好ましくは、複数のマイクロレンズの各々は、表面に形成された反射防止膜を有する。 More preferably, each of the plurality of microlenses has an antireflection film formed on the surface.
　本発明によれば、マイクロレンズの外形を工夫することにより、固体撮像装置におけるフレアの発生を抑制することができる。 According to the present invention, flare generation in the solid-state imaging device can be suppressed by devising the outer shape of the microlens.
従来の固体撮像装置におけるフレアの発生状況を示す図である。It is a figure which shows the generation | occurrence | production state of the flare in the conventional solid-state imaging device. フレアの発生要因を説明するための従来の固体撮像装置の断面図である。It is sectional drawing of the conventional solid-state imaging device for demonstrating the generation | occurrence | production factor of flare. 本発明の第１の実施形態に係る固体撮像装置の断面図である。1 is a cross-sectional view of a solid-state imaging device according to a first embodiment of the present invention. 図３中のマイクロレンズの平面図である。FIG. 4 is a plan view of the microlens in FIG. 3. 図４のＶ－Ｖ断面図である。FIG. 5 is a VV cross-sectional view of FIG. 4. 図４の変形例を示すマイクロレンズの平面図である。It is a top view of the micro lens which shows the modification of FIG. 図６のＶII－ＶII断面図である。FIG. 7 is a sectional view taken along line VII-VII in FIG. 6. 本発明の第２の実施形態に係る固体撮像装置の断面図である。It is sectional drawing of the solid-state imaging device which concerns on the 2nd Embodiment of this invention.
　以下に、好ましい実施形態を挙げて説明する。 Hereinafter, a preferred embodiment will be described.
　（第１の実施形態）
　図１は、従来の固体撮像装置におけるフレアの発生状況を示す図であって、暗室にて高輝度光源を撮影した写真を示している。図１の写真では、高輝度光源の画像の周辺に放射状にフレアが発生しているのが判る。特に、マゼンダ色のフレアは視認されやすく大きな課題となる。 (First embodiment)
FIG. 1 is a diagram showing the occurrence of flare in a conventional solid-state imaging device, and shows a photograph taken of a high-intensity light source in a dark room. In the photograph of FIG. 1, it can be seen that flares are radially generated around the image of the high-intensity light source. In particular, magenta flare is a big problem because it is easily visible.
　図２は、従来の固体撮像装置の断面図である。図２の固体撮像装置は、不図示のシリコン基板の主面上に設けられた半導体層７を備えている。半導体層７は、各々画素を構成する複数のフォトダイオード（不図示）を有している。図２の固体撮像装置は、半導体層７の上にＲＧＢのカラーフィルタ６を形成し、その上に平坦化膜９を介して画素毎のマイクロレンズ８を設け、これをシールガラス１２で封止し、更にＩＲカットフィルタ１３を設けたものである。従来のマイクロレンズ８の形状は、図２に示すような半球型、すなわち断面半円型に近いものが一般的であった。 FIG. 2 is a cross-sectional view of a conventional solid-state imaging device. The solid-state imaging device of FIG. 2 includes a semiconductor layer 7 provided on the main surface of a silicon substrate (not shown). The semiconductor layer 7 has a plurality of photodiodes (not shown) each constituting a pixel. In the solid-state imaging device of FIG. 2, an RGB color filter 6 is formed on a semiconductor layer 7, and a microlens 8 for each pixel is provided thereon via a planarizing film 9, which is sealed with a sealing glass 12. Further, an IR cut filter 13 is provided. The shape of the conventional microlens 8 is generally a hemispherical shape as shown in FIG.
　図２は、従来の固体撮像装置にてフレアが発生する要因を説明する図でもある。ＩＲカットフィルタ１３及びシールガラス１２を透過した入射光はマイクロレンズ８へ到達し、その大部分はマイクロレンズ８で集光されてカラーフィルタ６を透過し、半導体層７の中の画素へ入射する。一方、マイクロレンズ８の表面で反射した光（反射率は４．５％程度）は、斜めに進んで一部がシールガラス１２の外面で反射され、他の一部がＩＲカットフィルタ１３の内面で反射される。図２では、シールガラス１２の外面における反射角をθ１とし、ＩＲカットフィルタ１３の内面における反射角をθ２としている。シールガラス１２及びＩＲカットフィルタ１３でそれぞれ反射した光は、離れた位置にある画素へ入射する。これがフレアの発生要因である。 FIG. 2 is also a diagram for explaining the cause of flare in a conventional solid-state imaging device. Incident light that has passed through the IR cut filter 13 and the seal glass 12 reaches the microlens 8, most of which is condensed by the microlens 8, passes through the color filter 6, and enters the pixels in the semiconductor layer 7. . On the other hand, the light reflected on the surface of the microlens 8 (reflectance is about 4.5%) proceeds obliquely, and part of the light is reflected on the outer surface of the seal glass 12, while the other part is the inner surface of the IR cut filter 13. Reflected by. In FIG. 2, the reflection angle on the outer surface of the seal glass 12 is θ1, and the reflection angle on the inner surface of the IR cut filter 13 is θ2. The light reflected by the seal glass 12 and the IR cut filter 13 is incident on a pixel at a distant position. This is the cause of flare.
　本願発明者は、図１のフレアの発生状況を解析することにより、図２中の角度θ１及びθ２が４０°以上かつ８０°以下の範囲にある反射光がフレアの原因たる迷光であって、この範囲におけるマイクロレンズ表面での反射光を無くせば、フレアの発生を抑制できることを見出した。本発明は、この知見をもとにマイクロレンズの外形を工夫したものである。 The inventor of the present application analyzes the flare generation state of FIG. 1, and the reflected light in the range where the angles θ1 and θ2 in FIG. 2 are 40 ° or more and 80 ° or less is stray light causing flare, It has been found that flare generation can be suppressed by eliminating the reflected light on the microlens surface in this range. The present invention devises the outer shape of the microlens based on this knowledge.
　図３は、本発明の第１の実施形態に係る固体撮像装置の断面図である。図３の固体撮像装置は、シリコン基板１の主面上に、各々画素を構成する複数のフォトダイオード２に加えて、ゲート３と、配線層４と、埋め込み層５とを形成し、その上にＲＧＢのカラーフィルタ６を設け、更に平坦化膜９を介して画素毎のマイクロレンズ１４を設けたものである。シリコン基板１は３５ｍｍフルサイズ規格の基板であって、上から見た各画素のサイズは６μｍ×６μｍである。複数のマイクロレンズ１４の各々は、入射光を対応する画素へ導くように断面五角形の凸形状に形成されたものであって、頂点側に位置する第１の外面２１と、基部側に位置する第２の外面２２との２外面のみを有する。なお、図３の固体撮像装置は、マイクロレンズの外形が異なる点を除いて図２に示した従来の固体撮像装置と同一の構造及びサイズを有するが、図３ではシールガラス及びＩＲカットフィルタの図示を省略している。 FIG. 3 is a cross-sectional view of the solid-state imaging device according to the first embodiment of the present invention. The solid-state imaging device of FIG. 3 forms a gate 3, a wiring layer 4, and a buried layer 5 on a main surface of a silicon substrate 1 in addition to a plurality of photodiodes 2 each constituting a pixel. Are provided with an RGB color filter 6 and a micro lens 14 for each pixel via a planarizing film 9. The silicon substrate 1 is a 35 mm full size standard substrate, and the size of each pixel viewed from above is 6 μm × 6 μm. Each of the plurality of microlenses 14 is formed in a convex shape having a pentagonal cross section so as to guide incident light to the corresponding pixel, and is located on the first outer surface 21 located on the apex side and on the base side. It has only two outer surfaces with the second outer surface 22. The solid-state imaging device of FIG. 3 has the same structure and size as the conventional solid-state imaging device shown in FIG. 2 except that the external shape of the microlens is different. In FIG. The illustration is omitted.
　図３の固体撮像装置への入射光は、マイクロレンズ１４を透過した後、カラーフィルタ６を透過し、配線層４の間に形成された埋め込み層５を通過してフォトダイオード２へ入射する。埋め込み層５には、高屈折率材料である窒化シリコンを用いる。高屈折率材料である窒化シリコンにより光の閉じ込めができ光導波路のような働きが得られるので、非常に高感度なデバイスが実現される。また、フォトダイオード２で光電変換により得られた各画素の電気信号は、シリコン基板１上に形成されたゲート３により読み出される。 3 is incident on the photodiode 2 after passing through the color filter 6 and passing through the buried layer 5 formed between the wiring layers 4 after passing through the microlens 14. For the buried layer 5, silicon nitride which is a high refractive index material is used. Since silicon nitride, which is a high refractive index material, can confine light and functions like an optical waveguide, an extremely sensitive device is realized. In addition, the electrical signal of each pixel obtained by photoelectric conversion by the photodiode 2 is read by the gate 3 formed on the silicon substrate 1.
　図４は図３中のマイクロレンズ１４の平面図であり、図５は図４にて対角線方向に延びる切断面に沿ったＶ－Ｖ断面図である。図４のように、マイクロレンズ１４は、上から見ると、画素を構成するフォトダイオード２の平面形状に対応して、ほぼ矩形の外形を有している。第１の外面２１は、円錐の側面の形をなす。図５にて、符号２０は、シリコン基板１の主面に対して平行な基準面を表す。第１の外面２１と基準面２０とのなす角度をαとすると、α＜２０°である。また、第２の外面２２と基準面２０とのなす角度をβとすると、β＞４０°である。マイクロレンズ１４の外面は第１及び第２の外面２１，２２のみであるので、マイクロレンズ１４は、基準面２０となす角度が２０°以上かつ４０°以下となる外面を有しない。 4 is a plan view of the microlens 14 in FIG. 3, and FIG. 5 is a VV cross-sectional view along a cut surface extending in a diagonal direction in FIG. As shown in FIG. 4, when viewed from above, the microlens 14 has a substantially rectangular outer shape corresponding to the planar shape of the photodiode 2 constituting the pixel. The first outer surface 21 is in the form of a conical side. In FIG. 5, reference numeral 20 represents a reference plane parallel to the main surface of the silicon substrate 1. If the angle formed by the first outer surface 21 and the reference surface 20 is α, α <20 °. If the angle formed between the second outer surface 22 and the reference surface 20 is β, β> 40 °. Since the outer surface of the microlens 14 is only the first and second outer surfaces 21 and 22, the microlens 14 does not have an outer surface whose angle with the reference surface 20 is 20 ° or more and 40 ° or less.
　図５に示すように、第１の面２１における光の反射角をθａとすると、θａ＝２αであるから、θａ＜４０°である。このため、第１の面２１からの反射光がシールガラスやＩＲカットフィルタで再反射しても、離れた位置のマイクロレンズへ入射することはなく、極めて狭い範囲の隣接マイクロレンズへ入射することになる。一方、第２の面２２における光の反射角をθｂとすると、θｂ＝２βであるから、θｂ＞８０°である。このため、第２の面２２からの反射光は、直近の隣接マイクロレンズへ入射することになる。したがって、マイクロレンズ１４の外面で反射して、離れた位置のマイクロレンズへ入射することにより生じるフレアは、本発明により抑制される。 As shown in FIG. 5, assuming that the reflection angle of light on the first surface 21 is θa, θa = 2α, and θa <40 °. For this reason, even if the reflected light from the first surface 21 is re-reflected by the seal glass or the IR cut filter, it does not enter the micro lens at a distant position, but enters the adjacent micro lens in a very narrow range. become. On the other hand, when the reflection angle of light on the second surface 22 is θb, θb = 2β, and θb> 80 °. For this reason, the reflected light from the second surface 22 enters the nearest adjacent microlens. Therefore, flare caused by reflection on the outer surface of the microlens 14 and entering the microlens at a distant position is suppressed by the present invention.
　図４及び図５に示したマイクロレンズ１４の形状は、例えば、レンズ材料であるレジストに対してリソグラフィ処理を施すことにより実現される。使用するマスクには通常のパターニングとは異なる処理が施され、諧調をもって現像される仕組みとする。リソグラフィと現像処理だけでマイクロレンズ１４が形成されるため、コストも安い。また、従来の半球型のマイクロレンズと同等の感度や入射角特性を得ることができる。 The shape of the microlens 14 shown in FIGS. 4 and 5 is realized, for example, by performing a lithography process on a resist that is a lens material. The mask to be used is subjected to processing different from normal patterning and is developed with gradation. Since the microlens 14 is formed only by lithography and development processing, the cost is low. Further, sensitivity and incident angle characteristics equivalent to those of a conventional hemispherical microlens can be obtained.
　図６は図４の変形例を示すマイクロレンズ１４の平面図であり、図７は図６のＶII－ＶII断面図である。図６及び図７のマイクロレンズ１４は、頂点側に位置する第１の外面２１と、基部側に位置する第２の外面２２とに加えて、画素の対角方向のギャップを埋める第３の外面２３を有する。しかも、第１の外面２１と基板主面とのなす角度は２０°より小であり、かつ第２の外面２２と基板主面とのなす角度は４０°より大であり、かつ第３の外面２３と基板主面とのなす角度は２０°より小である。 6 is a plan view of a microlens 14 showing a modification of FIG. 4, and FIG. 7 is a sectional view taken along line VII-VII in FIG. The microlens 14 shown in FIGS. 6 and 7 includes a third outer surface that fills the diagonal gap of the pixels in addition to the first outer surface 21 located on the apex side and the second outer surface 22 located on the base side. It has an outer surface 23. Moreover, the angle formed between the first outer surface 21 and the substrate main surface is smaller than 20 °, and the angle formed between the second outer surface 22 and the substrate main surface is larger than 40 °, and the third outer surface. The angle formed between 23 and the main surface of the substrate is smaller than 20 °.
　図６及び図７の構成によれば、第１及び第２の外面２１，２２を透過した光だけでなく第３の外面２３を透過した光も同じ画素へ導かれるので、図４及び図５の構成に比べて入射光の利用効率が向上する。 6 and 7, not only the light transmitted through the first and second outer surfaces 21 and 22 but also the light transmitted through the third outer surface 23 are guided to the same pixel. The utilization efficiency of incident light is improved as compared with the above configuration.
　なお、マイクロレンズ１４は、基板主面となす角度が２０°以上かつ４０°以下となる外面を有しないことを条件に、種々の外形をとり得る。例えば、複数の外面のうち少なくとも１つは、断面外形が直線状でなく曲線状であってもよい。また、複数の外面のうち頂点側に位置する第１の外面の部分は、断面半円型であってもよい。 Note that the microlens 14 can have various outer shapes on condition that the angle formed with the main surface of the substrate does not have an outer surface that is 20 ° or more and 40 ° or less. For example, at least one of the plurality of outer surfaces may have a curved outer shape in cross section. Further, the portion of the first outer surface located on the apex side among the plurality of outer surfaces may be semicircular in cross section.
　（第２の実施形態）
　図８は、本発明の第２の実施形態に係る固体撮像装置の断面図である。図８の固体撮像装置は、図３中のマイクロレンズ１４の表面に、屈折率の低い（屈折率ｎ＝１．４～１．５程度）材料からなる反射防止膜１５を形成したものである。例えば、ＣＶＤ処理によりＳｉＯ２を９５ｎｍ成膜したものを、反射防止膜１５とする。このとき、マイクロレンズ１４のサイズは成膜分を見込んで予め小さく作成しておく。 (Second Embodiment)
FIG. 8 is a cross-sectional view of a solid-state imaging device according to the second embodiment of the present invention. The solid-state imaging device of FIG. 8 is obtained by forming an antireflection film 15 made of a material having a low refractive index (refractive index n = about 1.4 to 1.5) on the surface of the microlens 14 in FIG. . For example, the antireflection film 15 is formed by depositing SiO 2 with a thickness of 95 nm by CVD. At this time, the size of the microlens 14 is prepared in advance in consideration of the amount of film formation.
　本実施形態によれば、マイクロレンズ１４の表面の反射率が４．５％から例えば２．９％へ低減され、フレアの抑制がより確実となる。また、反射防止膜１５は無機物であるため表面洗浄が容易となり、後の組み立て工程で非常に扱いやすくなる。 According to the present embodiment, the reflectance of the surface of the microlens 14 is reduced from 4.5% to 2.9%, for example, and flare can be more reliably suppressed. Further, since the antireflection film 15 is made of an inorganic material, the surface can be easily cleaned, and it becomes very easy to handle in the subsequent assembly process.
　なお、以上の第１及び第２の実施形態にて、シリコン基板１に代えて、他の種類の半導体基板を用いてもよいし、半導体以外の基板を用いてもよい。 In the first and second embodiments described above, other types of semiconductor substrates may be used instead of the silicon substrate 1, or substrates other than semiconductors may be used.
　本発明は、フレアの発生が抑制された画像が出力可能な固体撮像装置を実現できて有用である。 The present invention is useful because it can realize a solid-state imaging device capable of outputting an image in which the occurrence of flare is suppressed.
１　シリコン基板
２　フォトダイオード（画素）
３　ゲート
４　配線層
５　埋め込み層
６　カラーフィルタ
７　半導体層
８　マイクロレンズ
９　平坦化膜
１２　シールガラス
１３　ＩＲカットフィルタ
１４　マイクロレンズ
１５　反射防止膜
２０　基準面
２１　第１の外面
２２　第２の外面
２３　第３の外面 1 Silicon substrate 2 Photodiode (pixel)
3 Gate 4 Wiring layer 5 Embedded layer 6 Color filter 7 Semiconductor layer 8 Micro lens 9 Flattening film 12 Seal glass 13 IR cut filter 14 Micro lens 15 Antireflection film 20 Reference surface 21 First outer surface 22 Second outer surface 23 First 3 exterior

Claims (3)

  1. 　主面に複数の画素が形成されてなる基板と、
    　各々入射光を前記複数の画素のうちの対応する画素へ導くための複数のマイクロレンズとを備えた固体撮像装置であって、
    　前記複数のマイクロレンズの各々は、前記基板の主面となす角度が２０°以上かつ４０°以下となる外面を有しないことを特徴とする固体撮像装置。     A substrate having a plurality of pixels formed on the main surface;
    A solid-state imaging device including a plurality of microlenses for guiding incident light to a corresponding pixel among the plurality of pixels,
    Each of the plurality of microlenses does not have an outer surface whose angle with the main surface of the substrate is 20 ° or more and 40 ° or less.
  2. 　請求項１記載の固体撮像装置において、
    　前記複数のマイクロレンズの各々は、頂点側に位置する第１の外面と、基部側に位置する第２の外面とを有し、
    　前記第１の外面と前記基板の主面とのなす角度は２０°より小であり、かつ前記第２の外面と前記基板の主面とのなす角度は４０°より大であることを特徴とする固体撮像装置。     The solid-state imaging device according to claim 1,
    Each of the plurality of microlenses has a first outer surface located on the apex side and a second outer surface located on the base side,
    The angle formed between the first outer surface and the main surface of the substrate is smaller than 20 °, and the angle formed between the second outer surface and the main surface of the substrate is larger than 40 °. Solid-state imaging device.
  3. 　請求項１又は２に記載の固体撮像装置において、
    　前記複数のマイクロレンズの各々は、表面に形成された反射防止膜を有することを特徴とする固体撮像装置。     The solid-state imaging device according to claim 1 or 2,
    Each of the plurality of microlenses has an antireflection film formed on a surface thereof.
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