JP6587581B2 - Solid-state imaging device - Google Patents
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Description
本発明は、固体撮像装置に関する。 The present invention relates to a solid-state imaging device.
特許文献１には、裏面照射型の固体撮像装置において、裏面に入射した光をフォトセンサによって検出し易くするために、基板の厚さが薄くされうることが記載されている。本明細書に添付された図８には、特許文献１の図１Ｃに記載された裏面照射型の固体撮像装置が引用されている。特許文献１に記載された撮像装置は、半導体装置基板（１０４）の裏面に入射しそれを透過した光子を該半導体装置基板に形成されたフォトセンサ（１１０）に向けて反射する反射部（１２８）が設けられている。 Patent Document 1 describes that in a back-illuminated solid-state imaging device, the thickness of the substrate can be reduced in order to easily detect light incident on the back surface by a photosensor. In FIG. 8 attached to this specification, the back-illuminated solid-state imaging device described in FIG. 1C of Patent Document 1 is cited. The imaging device described in Patent Document 1 includes a reflection unit (128) that reflects photons incident on and transmitted through the back surface of a semiconductor device substrate (104) toward a photosensor (110) formed on the semiconductor device substrate. ) Is provided.
しかしながら、特許文献１に記載された構成では、反射部（１２８）によってフォトセンサ（１１０）に向けて反射された光子は、半導体装置基板（１０４）と絶縁層１１８との界面（１０６ｆ）によって反射部（１２８）に向けて反射される。したがって、界面（１０６ｆ）と反射部（１２８）との間で多重反射が起こる。また、界面（１０６ｆ）と反射部（１２８）との距離が撮像面にわたって均一でない場合には、フォトセンサ（１１０）に戻る光子の量がばらつくので、感度ばらつきが生じうる。
本発明は、上記の課題認識を契機としてなされたものであり、感度の向上と感度のばらつきの低減のために有利な技術を提供することを目的とする。
However, in the configuration described in Patent Document 1, the photons reflected toward the photosensor (110) by the reflecting portion (128) are reflected by the interface (106f) between the semiconductor device substrate (104) and the insulating layer 118. Reflected toward the portion (128). Therefore, multiple reflection occurs between the interface (106f) and the reflecting portion (128). In addition, when the distance between the interface (106f) and the reflecting portion (128) is not uniform across the imaging surface, the amount of photons returning to the photosensor (110) varies, and thus sensitivity variations may occur.
The present invention has been made with the above problem recognition as an opportunity, and an object thereof is to provide an advantageous technique for improving sensitivity and reducing variation in sensitivity.
本発明の１つの側面は、複数の光電変換部を有する半導体層と、前記半導体層の第１面の側に配置された配線構造と、前記半導体層の第２面の側に配置された複数のマイクロレンズと、前記複数のマイクロレンズと前記半導体層の間に配された、緑色のカラーフィルタおよび青色のカラーフィルタを含むカラーフィルタ層と、を有する固体撮像装置に関し、前記配線構造は、第１配線層と、前記第１配線層よりも前記半導体層から離れて配された第２配線層と、前記第１配線層と前記半導体層との間、および、前記第１配線層と前記第２配線層との間に位置する絶縁膜と、を含み、前記複数の光電変換部の各々の間には素子分離部が設けられており、前記複数の光電変換部のうち前記緑色のカラーフィルタに対応する光電変換部が配置された複数の緑色の画素領域の各々と、前記複数の光電変換部のうち青色のカラーフィルタに対応する光電変換部が配置された複数の青色の画素領域の各々と、において、前記絶縁膜と前記半導体層との間には、トランジスタのゲート電極が設けられており、前記第１配線層は、前記光電変換部に重なり前記ゲート電極および前記第２配線層に重ならない第１部分と、前記ゲート電極に重なる第４部分とを有し、前記第１部分と前記第４部分とは連続していて、かつ、前記第２配線層は、前記ゲート電極に重なる第２部分と、前記ゲート電極に重ならない第３部分を有し、かつ、前記第２面に垂直で前記第１部分、前記第２部分および前記第３部分を含む断面において、前記第１部分の幅が前記第２部分の幅および前記第３部分の幅よりも大きく、前記第１部分のうち前記半導体層に対向する面は前記第１面に平行であり、かつ、前記第１部分と前記光電変換部との間には前記第１面に接触して配置された第１の誘電体膜と、前記絶縁膜と前記第１の誘電体膜との間に配置された、前記第１の誘電体膜および前記絶縁膜とは屈折率の異なる第２の誘電体膜と、が設けられていて、かつ、前記第１の誘電体膜および前記第２の誘電体膜は前記ゲート電極と前記絶縁膜との間に位置する部分を有し、前記複数の緑色の画素領域の間において、前記第１部分と前記光電変換部との間における前記絶縁膜の厚さが、不均一性を有しており、前記複数の緑色の画素領域の各々において、前記第１部分は前記半導体層を透過した光を前記半導体層に向けて反射する反射面を含み、前記第１の誘電体膜および前記第２の誘電体膜は、前記半導体層を透過して前記反射面で前記半導体層に向けて反射された光が、前記半導体層の前記第１面で反射することを抑制するように構成されており、前記絶縁膜は、前記半導体層からの距離が前記第１配線層より小さい位置において、前記複数の緑色の画素領域の各々の前記第１部分と前記光電変換部との間から、前記複数の青色の画素領域の各々の前記第１部分と前記光電変換部との間まで延在しており、前記絶縁膜の一部が、前記複数の緑色の画素領域の各々の前記第１部分と前記複数の青色の画素領域の各々の前記第１部分と、の間に位置し、前記絶縁膜の前記一部が前記素子分離部に重なる。 One aspect of the present invention includes a semiconductor layer having a plurality of photoelectric conversion units, a wiring structure disposed on the first surface side of the semiconductor layer, and a plurality of layers disposed on the second surface side of the semiconductor layer. And a color filter layer including a green color filter and a blue color filter disposed between the plurality of microlenses and the semiconductor layer, and the wiring structure includes: A first wiring layer, a second wiring layer disposed farther from the semiconductor layer than the first wiring layer, between the first wiring layer and the semiconductor layer, and between the first wiring layer and the first wiring layer. And an insulating film positioned between the two wiring layers, and an element isolation unit is provided between each of the plurality of photoelectric conversion units, and the green color filter among the plurality of photoelectric conversion units The photoelectric conversion unit corresponding to Each of a plurality of green pixel regions and each of a plurality of blue pixel regions where a photoelectric conversion unit corresponding to a blue color filter among the plurality of photoelectric conversion units is disposed, and the insulating film and the semiconductor A gate electrode of a transistor is provided between the first wiring layer, the first wiring layer overlapping the photoelectric conversion portion, a first portion not overlapping the gate electrode and the second wiring layer, and the gate electrode A fourth portion overlapping the gate electrode, the first portion and the fourth portion are continuous, and the second wiring layer overlaps the second portion overlapping the gate electrode and the gate electrode. A cross section including the first portion, the second portion, and the third portion perpendicular to the second surface and including the first portion, the width of the second portion, and the width of the second portion; Larger than the width of the third part, Of the first portion, a surface facing the semiconductor layer is parallel to the first surface, and is disposed between the first portion and the photoelectric conversion unit in contact with the first surface. A first dielectric film and a second dielectric film disposed between the insulating film and the first dielectric film and having a refractive index different from that of the first dielectric film and the insulating film; And the first dielectric film and the second dielectric film have a portion located between the gate electrode and the insulating film, and the plurality of green pixels Between the regions, the thickness of the insulating film between the first portion and the photoelectric conversion unit has non-uniformity, and in each of the plurality of green pixel regions, the first portion Includes a reflective surface that reflects light transmitted through the semiconductor layer toward the semiconductor layer, and includes the first dielectric film and the first dielectric film. Fine said second dielectric film suppresses so that the semiconductor layer a transmittance to light reflected toward the semiconductor layer in the reflective surface, reflected by the first surface of the front Symbol semiconductor layer The insulating film is formed between the first portion of each of the plurality of green pixel regions and the photoelectric conversion unit at a position where the distance from the semiconductor layer is smaller than the first wiring layer. To a portion between the first portion of each of the plurality of blue pixel regions and the photoelectric conversion unit, and a part of the insulating film is formed on the plurality of green pixel regions. The insulating film is located between the first portion and the first portion of each of the plurality of blue pixel regions, and the part of the insulating film overlaps the element isolation portion.
本発明は、感度の向上と感度のばらつきの低減のために有利な技術が提供される。 The present invention provides an advantageous technique for improving sensitivity and reducing variation in sensitivity.
図１Ａ、１Ｂ〜図６を参照しながら本発明の第１実施形態の固体撮像装置１００について説明する。図１Ａは、固体撮像装置１００をその撮像面に垂直な面で切断した模式的な断面図であり、簡単化のために２つの画素のみが示されている。ここで、撮像面とは、複数の画素が配列されて構成された画素アレイが配置された面である。図１Ｂは、固体撮像装置１００の反射防止層１１４をその撮像面に垂直な面（図１Ａとは異なる面）で切断した模式的な断面の拡大図である。図２は、固体撮像装置１００をその撮像面に平行な面である図１ＡのＡ−Ａ’面で切断した模式的な断面図である。固体撮像装置１００は、例えば、ＭＯＳ型イメージセンサとして、又は、ＣＣＤイメージセンサとして構成されうる。 A solid-state imaging device 100 according to a first embodiment of the present invention will be described with reference to FIGS. 1A and 1B to FIG. FIG. 1A is a schematic cross-sectional view of the solid-state imaging device 100 cut along a plane perpendicular to the imaging plane, and only two pixels are shown for simplicity. Here, the imaging surface is a surface on which a pixel array configured by arranging a plurality of pixels is arranged. FIG. 1B is an enlarged view of a schematic cross section in which the antireflection layer 114 of the solid-state imaging device 100 is cut along a plane perpendicular to the imaging plane (a plane different from FIG. 1A). FIG. 2 is a schematic cross-sectional view of the solid-state imaging device 100 cut along an A-A ′ plane in FIG. 1A that is a plane parallel to the imaging plane. The solid-state imaging device 100 can be configured as, for example, a MOS image sensor or a CCD image sensor.
固体撮像装置１００は、第１面１２０および第２面１２１を有する半導体層１０１を有する。半導体層１０１は、例えば、シリコン基板で構成されうる。固体撮像装置１００は、更に、半導体層１０１の第１面１２０の側に配置された配線構造ＷＳと、半導体層１０１の第２面１２１の側に配置されたカラーフィルタ層１０７とを有する。カラーフィルタ層１０７は、第１カラーフィルタ１０７ａ、第２カラーフィルタ１０７ｂ、第３カラーフィルタ１０７ｃ（不図示）を含みうる。ここで、第１カラーフィルタ１０７ａは青色のカラーフィルタ、第２カラーフィルタ１０７ｂは緑色のカラーフィルタ、第３カラーフィルタ１０７ｃは赤色のカラーフィルタでありうる。第１カラーフィルタ１０７ａ、第２カラーフィルタ１０７ｂおよび第３カラーフィルタ１０７ｃの配列は、例えば、ベイヤー配列に従いうる。 The solid-state imaging device 100 includes a semiconductor layer 101 having a first surface 120 and a second surface 121. The semiconductor layer 101 can be composed of, for example, a silicon substrate. The solid-state imaging device 100 further includes a wiring structure WS disposed on the first surface 120 side of the semiconductor layer 101 and a color filter layer 107 disposed on the second surface 121 side of the semiconductor layer 101. The color filter layer 107 may include a first color filter 107a, a second color filter 107b, and a third color filter 107c (not shown). Here, the first color filter 107a may be a blue color filter, the second color filter 107b may be a green color filter, and the third color filter 107c may be a red color filter. The arrangement of the first color filter 107a, the second color filter 107b, and the third color filter 107c can follow a Bayer arrangement, for example.
固体撮像装置１００は、更に、カラーフィルタ層１０７の上にアレイ状に配列された複数のマイクロレンズ１０８を有しうる。固体撮像装置１００は、更に、半導体層１０１の第２面１２１とカラーフィルタ層１０７との間に平坦化層１０６を有しうる。平坦化層１０６は、例えば、カラーフィルタ層１０７の下地膜として機能させることができる。撮像時に、光は、マイクロレンズ１０８を通して光電変換部１０２に入射する。ここで、マイクロレンズ１０８は、半導体層１０１の第２面１２１の側に配置され、配線構造ＷＳは、半導体層１０１の第１面１２０の側に配置されている。このように、配線構造が設けられた第１面の側とは反対側の第２面の側から光を入射させる固体撮像装置は、裏面照射型の固体撮像装置と呼ばれうる。 The solid-state imaging device 100 can further include a plurality of microlenses 108 arranged in an array on the color filter layer 107. The solid-state imaging device 100 can further include a planarization layer 106 between the second surface 121 of the semiconductor layer 101 and the color filter layer 107. The planarization layer 106 can function as a base film of the color filter layer 107, for example. At the time of imaging, light enters the photoelectric conversion unit 102 through the microlens 108. Here, the microlens 108 is disposed on the second surface 121 side of the semiconductor layer 101, and the wiring structure WS is disposed on the first surface 120 side of the semiconductor layer 101. As described above, the solid-state imaging device in which light is incident from the second surface side opposite to the first surface side where the wiring structure is provided can be referred to as a back-illuminated solid-state imaging device.
半導体層１０１には、複数の光電変換部１０２が形成されている。半導体層１０１と光電変換部１０２とは、互いに反対導電型の不純物半導体領域で構成され、半導体層１０１と光電変換部１０２とによってＰＮ接合（フォトダイオード）が形成されている。光電変換部１０２は、信号として読み出される電荷の極性と同一の極性を有するキャリアを多数キャリアとする領域である。半導体層１０１には、隣接する光電変換部１０２を相互に分離する素子分離部１０３が形成されうる。素子分離部１０３は、光電変換部１０２の導電型とは反対の導電型を有する不純物半導体領域、および／または、絶縁体を有しうる。ここで、絶縁体は、ＬＯＣＯＳ分離またはＳＴＩ分離等でありうる。 A plurality of photoelectric conversion units 102 are formed in the semiconductor layer 101. The semiconductor layer 101 and the photoelectric conversion unit 102 are configured by impurity semiconductor regions having opposite conductivity types, and the semiconductor layer 101 and the photoelectric conversion unit 102 form a PN junction (photodiode). The photoelectric conversion unit 102 is a region in which carriers having the same polarity as the polarity of charges read as a signal are majority carriers. In the semiconductor layer 101, an element isolation part 103 that isolates adjacent photoelectric conversion parts 102 from each other can be formed. The element isolation portion 103 can include an impurity semiconductor region having a conductivity type opposite to that of the photoelectric conversion portion 102 and / or an insulator. Here, the insulator may be LOCOS isolation or STI isolation.
固体撮像装置１００の撮像領域は、格子状に隙間なく配列された複数の画素領域ＰＲによって構成され、複数の光電変換部１０２のそれぞれは、複数の画素領域ＰＲのうち対応する画素領域ＰＲに配置されている。画素領域ＰＲの面積は、撮像領域の面積を画素数（光電変換部１０２の数）で割った値である。 The imaging region of the solid-state imaging device 100 is configured by a plurality of pixel regions PR arranged in a lattice shape without gaps, and each of the plurality of photoelectric conversion units 102 is arranged in a corresponding pixel region PR among the plurality of pixel regions PR. Has been. The area of the pixel region PR is a value obtained by dividing the area of the imaging region by the number of pixels (the number of photoelectric conversion units 102).
固体撮像装置１００は、光電変換部１０２の信号を読み出すために半導体層１０１の第１面１２０に形成された複数のトランジスタＴｒを更に含む。トランジスタＴｒは、例えばポリシリコンで構成されるゲート電極１０４を含む。図１Ａ、図３では、トランジスタＴｒを構成するソース、ドレイン、ゲート酸化膜などは省略されている。固体撮像装置１００がＭＯＳ型イメージセンサとして構成される場合において、複数のトランジスタＴｒは、例えば、光電変換部１０２に蓄積された電荷を不図示のフローティングディフュージョンに転送するための転送トランジスタを含みうる。 The solid-state imaging device 100 further includes a plurality of transistors Tr formed on the first surface 120 of the semiconductor layer 101 in order to read signals from the photoelectric conversion unit 102. The transistor Tr includes a gate electrode 104 made of, for example, polysilicon. In FIG. 1A and FIG. 3, the source, drain, gate oxide film, etc. constituting the transistor Tr are omitted. In the case where the solid-state imaging device 100 is configured as a MOS image sensor, the plurality of transistors Tr may include, for example, transfer transistors for transferring charges accumulated in the photoelectric conversion unit 102 to a floating diffusion (not shown).
配線構造ＷＳは、積層配線部１０９と、層間絶縁膜１０５とを含む。積層配線部１０９は、例えば、反射面１４０を有する反射部１１３を含む第１配線層と、第２配線層１１０と、第３配線層１１１と、第４配線層１１２とを含みうる。層間絶縁膜１０５は、例えば、シリコン酸化物膜で形成されうる。層間絶縁膜１０５は、反射面１４０と第１面１２０との間の部分を含む。反射面１４０は、カラーフィルタ１０７ａ、１０７ｂ、１０７ｃを透過して光電変換部１０２に入射し光電変換部１０２を透過し更に第１面１２０を通過した光を光電変換部１０２に向けて反射する。積層配線部１０９を構成する反射部(第１配線層）１１３、第２配線層１１０、第３配線層１１１および第４配線層１１２は、例えば、アルミニウム、銅およびタングステンのいずれか１つを主成分として構成されうる。 The wiring structure WS includes a laminated wiring part 109 and an interlayer insulating film 105. The laminated wiring portion 109 can include, for example, a first wiring layer including a reflecting portion 113 having a reflecting surface 140, a second wiring layer 110, a third wiring layer 111, and a fourth wiring layer 112. The interlayer insulating film 105 can be formed of, for example, a silicon oxide film. The interlayer insulating film 105 includes a portion between the reflective surface 140 and the first surface 120. The reflection surface 140 reflects the light that has passed through the color filters 107 a, 107 b, and 107 c, entered the photoelectric conversion unit 102, transmitted through the photoelectric conversion unit 102, and passed through the first surface 120 toward the photoelectric conversion unit 102. The reflective portion (first wiring layer) 113, the second wiring layer 110, the third wiring layer 111, and the fourth wiring layer 112 that constitute the laminated wiring portion 109 are mainly made of, for example, aluminum, copper, or tungsten. It can be configured as an ingredient.
積層配線部１０９を構成する配線層の一部を反射部１１３として利用することにより、配線部を形成するための付加的な層が不要となる。また、積層配線部１０９を構成する複数の配線層のうち半導体層１０１の第１面１２０に最も近い第１配線層によって反射部１１３を形成することにより、反射面１４０と光電変換部１０２との距離が短くなり、迷光を低減することができる。その結果、感度が向上し、混色が低減される。 By using a part of the wiring layer constituting the laminated wiring part 109 as the reflection part 113, an additional layer for forming the wiring part becomes unnecessary. In addition, by forming the reflective portion 113 with the first wiring layer that is closest to the first surface 120 of the semiconductor layer 101 among the plurality of wiring layers constituting the multilayer wiring portion 109, the reflective surface 140 and the photoelectric conversion portion 102 are The distance is shortened and stray light can be reduced. As a result, sensitivity is improved and color mixing is reduced.
固体撮像装置１００は、第１面１２０における光の反射を低減するように第１面１２０に接触して配置された反射防止層１１４を備えている。反射防止層１１４は、例えば、複数の誘電体膜で形成されうる。反射防止層１１４を備えることにより、反射部１１３によって光電変換部１０２に向けて反射された光が第１面１２０で再び反射されることが抑制される。これにより、反射防止層１１４がない場合に比べて、より多くの光を反射部１１３により光電変換部１０２に戻すことができる。 The solid-state imaging device 100 includes an antireflection layer 114 disposed in contact with the first surface 120 so as to reduce light reflection on the first surface 120. The antireflection layer 114 can be formed of a plurality of dielectric films, for example. By providing the antireflection layer 114, the light reflected toward the photoelectric conversion unit 102 by the reflection unit 113 is prevented from being reflected again by the first surface 120. Accordingly, more light can be returned to the photoelectric conversion unit 102 by the reflection unit 113 than when the antireflection layer 114 is not provided.
図１Ｂには反射防止層１１４の構成例が示されている。反射防止層１１４を構成する複数の誘電体膜は、第１面１２０に接触して配置された第１の誘電体膜１１４１と、第１の誘電体膜１１４１とは屈折率の異なる第２の誘電体膜１１４２を含みうる。ここでは、第１の誘電体膜１１４１と第２の誘電体膜１１４２とが接触しているが、第１の誘電体膜１１４１と第２の誘電体膜１１４２との間に他の誘電体膜を配置してもよい。第１の誘電体膜１１４１および第２の誘電体膜１１４２は半導体層１０１より低い屈折率を有しうる。第２の誘電体膜１１４２は第１の誘電体膜１１４１よりも高い屈折率を有しうる。また、第２の誘電体膜１１４２は層間絶縁膜１０５よりも高い屈折率を有しうる。第１の誘電体膜１１４２は層間絶縁膜１０５と等しい屈折率を有しうる。第１の誘電体膜１１４２と層間絶縁膜１０５とで屈折率が等しくてもよいし、異なっていてもよい。 FIG. 1B shows a configuration example of the antireflection layer 114. The plurality of dielectric films constituting the antireflection layer 114 include a first dielectric film 1141 disposed in contact with the first surface 120, and a second dielectric film 1141 having a refractive index different from that of the first dielectric film 1141. A dielectric film 1142 may be included. Here, the first dielectric film 1141 and the second dielectric film 1142 are in contact with each other, but another dielectric film is interposed between the first dielectric film 1141 and the second dielectric film 1142. May be arranged. The first dielectric film 1141 and the second dielectric film 1142 may have a lower refractive index than the semiconductor layer 101. The second dielectric film 1142 can have a higher refractive index than the first dielectric film 1141. In addition, the second dielectric film 1142 can have a higher refractive index than the interlayer insulating film 105. The first dielectric film 1142 may have a refractive index equal to that of the interlayer insulating film 105. The first dielectric film 1142 and the interlayer insulating film 105 may have the same or different refractive indexes.
第１の誘電体膜１１４１および第２の誘電体膜１１４２の少なくとも一方、好ましくは両方が、層間絶縁膜１０５よりも薄くされうる。第１の誘電体膜１１４１の厚みと第２の誘電体膜１１４２の厚みの和以上である反射防止層１１４の厚みは層間絶縁膜１０５よりも薄くされうる。なお、ここでいう層間絶縁膜１０５の厚みは、層間絶縁膜１０５のうち、第１面１２０と反射面１４０との間に位置する部分の厚みを指している。第１の誘電体膜１１４１と第２の誘電体膜１１４２は互いに厚みが等しくてもよいし、異なっていてもよい。第２の誘電体膜１１４２と第１の誘電体膜１１４１との厚みが異なる場合、反射防止機能の性能は主に厚い方の誘電体膜の屈折率に依存しうる。第２の誘電体膜１１４２を第１の誘電体膜１１４１よりも厚くし、第２の誘電体膜１１４２が第１の誘電体膜１１４１よりも高い屈折率を有することで、反射防止の効果が向上する。 At least one of the first dielectric film 1141 and the second dielectric film 1142, preferably both, can be made thinner than the interlayer insulating film 105. The thickness of the antireflection layer 114 that is equal to or greater than the sum of the thickness of the first dielectric film 1141 and the thickness of the second dielectric film 1142 can be made thinner than the interlayer insulating film 105. Here, the thickness of the interlayer insulating film 105 refers to the thickness of the portion of the interlayer insulating film 105 located between the first surface 120 and the reflecting surface 140. The first dielectric film 1141 and the second dielectric film 1142 may have the same thickness or may be different from each other. When the thicknesses of the second dielectric film 1142 and the first dielectric film 1141 are different, the performance of the antireflection function can mainly depend on the refractive index of the thicker dielectric film. By making the second dielectric film 1142 thicker than the first dielectric film 1141 and the second dielectric film 1142 has a higher refractive index than the first dielectric film 1141, an antireflection effect is obtained. improves.
以下、具体的な例を提供するために、半導体層１０１の厚さが３μｍであるものとして、半導体層１０１による光の吸収、ならびに、反射部（第１配線層）１１３および反射防止層１１４の効果を説明する。第２面１２１に入射した光が第２面１２１と第１面１２０との間の半導体領域において吸収される割合（第２面１２１に入射した光に対する割合）は、光の波長によって異なる。光が第２面１２１に対して垂直に入射する場合を考える。この場合、第２面１２１を通過して第１面１２０に到達するまでの間に、青色のカラーフィルタ１０７ａを透過した波長４５０ｎｍの光はその殆どが吸収される。一方、緑色のカラーフィルタ１０７ｂを透過した波長５５０ｎｍの光はその約８７％が吸収され、赤色のカラーフィルタ１０７ｃを透過した波長６２０ｎｍの光はその約７０％が吸収される。このとき、図３に模式的に示すように、吸収されなかった光１１６は、反射部１１３によって第１面１２０に向けて反射される。反射防止層１１４は、例えば、第１面１２０の上に第１の誘電体膜１１４１として１０ｎｍ厚のシリコン酸化物膜と第２の誘電体膜１１４２として５０ｎｍ厚のシリコン窒化物膜とを順に配置した構成を有しうる。図４には、第１面１２０に反射防止層１１４を設けた場合（実線）と、反射防止層１１４を設けない場合（破線）とにおける第１面１２０の反射率の波長依存性が例示されている。図４において、横軸は光の波長、縦軸は第１面１２０の反射率である。
反射防止層１１４がない場合、反射部１１３の反射面１４０で反射された光は、第１面１２０に到達すると、第１面１２０で反射され、更に反射面１４０で反射される。これが繰り返されることによって反射面１４０と第１面１２０との間で多重反射が起こる。ここで、光の波長をλ、層間絶縁膜１０５の上面１３０と反射面１４０との距離（媒質の厚さ）をｄ、上面１３０と反射面１４０との間の媒質である層間絶縁膜１０５の屈折率をｎとする。また、第１面１２０における反射率をＲ１、反射面１４０を含み第１面１２０に平行な面の反射率をＲ２、第１面１２０および反射面１４０を含む反射構造部ＲＳの反射率をＲとする。反射面１４０と第１面１２０との間で光の多重反射が起こるため、反射率Ｒは、λ、ｄ、ｎ、Ｒ１、Ｒ２に依存する。反射率Ｒは、式（１）によって表すことができる。
Hereinafter, in order to provide a specific example, it is assumed that the thickness of the semiconductor layer 101 is 3 μm, the light absorption by the semiconductor layer 101, and the reflection part (first wiring layer) 113 and the antireflection layer 114. Explain the effect. The rate at which light incident on the second surface 121 is absorbed in the semiconductor region between the second surface 121 and the first surface 120 (ratio with respect to the light incident on the second surface 121) varies depending on the wavelength of the light. Consider a case where light is incident on the second surface 121 perpendicularly. In this case, most of the light having a wavelength of 450 nm that has passed through the blue color filter 107a is absorbed before passing through the second surface 121 and reaching the first surface 120. On the other hand, about 87% of the light having a wavelength of 550 nm transmitted through the green color filter 107b is absorbed, and about 70% of the light having a wavelength of 620 nm transmitted through the red color filter 107c is absorbed. At this time, as schematically shown in FIG. 3, the light 116 that has not been absorbed is reflected toward the first surface 120 by the reflecting portion 113. In the antireflection layer 114, for example, a 10 nm thick silicon oxide film as the first dielectric film 1141 and a 50 nm thick silicon nitride film as the second dielectric film 1142 are sequentially arranged on the first surface 120. The configuration can be as follows. FIG. 4 illustrates the wavelength dependence of the reflectance of the first surface 120 when the antireflection layer 114 is provided on the first surface 120 (solid line) and when the antireflection layer 114 is not provided (broken line). ing. In FIG. 4, the horizontal axis represents the wavelength of light, and the vertical axis represents the reflectance of the first surface 120.
When the antireflection layer 114 is not provided, the light reflected by the reflecting surface 140 of the reflecting portion 113 is reflected by the first surface 120 and further reflected by the reflecting surface 140 when reaching the first surface 120. By repeating this, multiple reflection occurs between the reflecting surface 140 and the first surface 120. Here, the wavelength of light is λ, the distance between the upper surface 130 of the interlayer insulating film 105 and the reflecting surface 140 (the thickness of the medium) is d, and the interlayer insulating film 105 that is a medium between the upper surface 130 and the reflecting surface 140 Let n be the refractive index. Further, the reflectance of the first surface 120 is R 1 , the reflectance of the surface including the reflective surface 140 and parallel to the first surface 120 is R 2 , and the reflectance of the reflective structure portion RS including the first surface 120 and the reflective surface 140. Is R. Since multiple reflection of light occurs between the reflection surface 140 and the first surface 120, the reflectance R depends on λ, d, n, R 1 , and R 2 . The reflectance R can be expressed by the formula (1).
・・・式（１）
図５には、反射構造部ＲＳの反射率Ｒが例示されている。横軸は媒質の厚さｄ、縦軸は反射率Ｒである。また、実線は、反射防止層１１４を有する場合の反射率Ｒであり、破線は、反射防止層１１４を有しない場合の反射率Ｒである。この例では、反射率Ｒ２を９０％、光の波長λを５５０ｎｍとしている。図５より、第１面１２０に反射防止層１１４を設けない場合に比べ、反射防止層１１４を設けた場合の方が、媒質の厚さｄの変化による反射率Ｒの変化が小さいことが分かる。したがって、反射防止層１１４を設けることにより、反射構造部ＲＳによって光電変換部１０２に戻される光の量の変化を低減することができる。これにより、媒質の厚さｄの不均一性、即ち、第１面１２０と反射部１１３との距離の不均一性による感度のばらつきを低減することができる。
きる。
... Formula (1)
FIG. 5 illustrates the reflectance R of the reflective structure RS. The horizontal axis represents the thickness d of the medium, and the vertical axis represents the reflectance R. The solid line represents the reflectance R when the antireflection layer 114 is provided, and the broken line represents the reflectance R when the antireflection layer 114 is not provided. In this example, the reflectance R 2 is 90%, and the light wavelength λ is 550 nm. FIG. 5 shows that the change in reflectance R due to the change in the thickness d of the medium is smaller when the antireflection layer 114 is provided than when the antireflection layer 114 is not provided on the first surface 120. . Therefore, by providing the antireflection layer 114, it is possible to reduce a change in the amount of light returned to the photoelectric conversion unit 102 by the reflection structure unit RS. Thereby, it is possible to reduce variation in sensitivity due to non-uniformity of the thickness d of the medium, that is, non-uniformity of the distance between the first surface 120 and the reflecting portion 113.
wear.
図５に示す例では反射率Ｒ２が９０％であるが、反射率Ｒ２の値は、反射構造部ＲＳの反射率Ｒがゼロより大きくなる値であればよい。ここで、反射率Ｒがゼロであると、光電変換部１０２へ戻る光がなくなり、感度を向上させることができない。 In the example illustrated in FIG. 5, the reflectance R 2 is 90%, but the value of the reflectance R 2 may be a value that makes the reflectance R of the reflective structure RS greater than zero. Here, when the reflectance R is zero, there is no light returning to the photoelectric conversion unit 102, and the sensitivity cannot be improved.
以下、反射率Ｒと反射率Ｒ２との関係について説明する。図６には、反射率Ｒと反射率Ｒ２との関係が例示されている。ここでは、光の波長λは５５０ｎｍ、層間絶縁膜１０５の屈折率ｎは１．４６とされている。また、第１面１２０の反射率Ｒ１は、反射防止層１１４を有しない場合におけるλ＝５５０ｎｍでの反射率である２２％とされている（図４参照）。 The following describes the relationship between the reflectance R and the reflectance R 2. Figure 6 shows the relationship between reflectance R and the reflectance R 2 are illustrated. Here, the wavelength λ of light is 550 nm, and the refractive index n of the interlayer insulating film 105 is 1.46. The reflectance R 1 of the first surface 120 is 22%, which is the reflectance at λ = 550 nm when the antireflection layer 114 is not provided (see FIG. 4).
式（１）より、媒質の厚さｄがλ／４ｎ（＝９４．２ｎｍ）の偶数倍であるときに反射構造部ＲＳの反射率Ｒは最小値となり、厚さｄがλ／４ｎの奇数倍であるときに反射率Ｒは最大値となる。図６には、厚さｄがλ／４ｎの偶数倍である５６５ｎｍであるときの反射率Ｒが実線で示され、厚さｄがλ／４ｎの奇数倍である４７１ｎｍであるときの反射率Ｒを破線で示されている。図６に示すように、媒質の厚さｄが５６５ｎｍであるときは、反射構造部ＲＳの反射率Ｒがゼロになる反射率Ｒ２の値が存在する。これは、第１面１２０で反射された光と反射部１１３で反射された光とが打ち消しあっていることを意味する。反射率Ｒ１は、反射防止層１１４の構成によって様々な値をとりうる。 From the equation (1), when the thickness d of the medium is an even multiple of λ / 4n (= 94.2 nm), the reflectance R of the reflective structure RS becomes the minimum value, and the thickness d is an odd number of λ / 4n. When it is doubled, the reflectance R becomes the maximum value. In FIG. 6, the reflectance R when the thickness d is 565 nm which is an even multiple of λ / 4n is indicated by a solid line, and the reflectance when the thickness d is 471 nm which is an odd multiple of λ / 4n. R is indicated by a broken line. As shown in FIG. 6, when the thickness d of the medium is 565nm, the reflectance values R 2 which reflectance R becomes zero reflecting structure portion RS is present. This means that the light reflected by the first surface 120 and the light reflected by the reflecting portion 113 cancel each other. The reflectance R 1 can take various values depending on the configuration of the antireflection layer 114.
図６および式（１）から、反射率Ｒ１と反射率Ｒ２とがＲ２＞Ｒ１を満たす場合には、反射率Ｒ＞０とすることができるといえる。これは、波長λおよび層間絶縁膜１０５の屈折率ｎには依存しない。つまり、反射率Ｒ２が反射率Ｒ１の最大値より大きければ、Ｒ＞０となって感度が向上する。ここで、反射率Ｒ１が最大値をとるのは、第１面１２０に反射防止層１１４を設けない場合である。図４の破線は、第１面１２０に反射防止層１１４を設けない場合の反射率を示している。図４より、短波長（青色）における反射率が高いことが分かる。また、青色のカラーフィルタ１０７ａを透過した青色域の光は、第１面１２０までは殆ど届かず、光電変換部１０２で光電変換されるので、緑色のカラーフィルタ１０７ｂおよび赤色のカラーフィルタ１０７ｃを透過した光を考慮すれば十分である。そこで、考慮すべき波長λは４８０ｎｍ程度以上と考えてよい。λ＝４８０ｎｍであるとき、第１面１２０に反射防止層１１４を設けない場合の反射率Ｒ１は２５％である（図４参照）。 From FIG. 6 and formula (1), it can be said that the reflectance R> 0 can be achieved when the reflectance R 1 and the reflectance R 2 satisfy R 2 > R 1 . This does not depend on the wavelength λ and the refractive index n of the interlayer insulating film 105. That is, reflectance R 2 is larger than the maximum value of the reflectance R 1, sensitivity is improved becomes R> 0. Here, the reflectance R 1 takes the maximum value when the antireflection layer 114 is not provided on the first surface 120. The broken line in FIG. 4 indicates the reflectance when the antireflection layer 114 is not provided on the first surface 120. FIG. 4 shows that the reflectance at a short wavelength (blue) is high. Also, the light in the blue region that has passed through the blue color filter 107a hardly reaches the first surface 120, and is photoelectrically converted by the photoelectric conversion unit 102, so that it passes through the green color filter 107b and the red color filter 107c. It is sufficient to take into account the light that has been removed. Therefore, the wavelength λ to be considered may be considered to be about 480 nm or more. When λ = 480 nm, the reflectance R 1 when the antireflection layer 114 is not provided on the first surface 120 is 25% (see FIG. 4).
反射部１１３の反射面１４０を含み第１面１２０に平行な面の反射率Ｒ２は、層間絶縁膜１０５の材料、反射部１１３の材料、画素領域ＰＲの面積に対する反射面１４０の面積の比率に依存する。ここで、反射面１４０の反射率（当該反射率は、反射部１１３の材料と層間絶縁膜１０５の材料とで決まる。）をＲ０とし、第１面１２０と平行な面における、１つの画素領域ＰＲの面積に対する１つの画素領域ＰＲにおける反射面１４０の面積の比率をＳとすると、反射率Ｒ２＝Ｒ０・Ｓがなりたつ。 Reflectivity R 2 of the plane parallel to the first face 120 includes a reflecting surface 140 of the reflecting section 113, the material of the interlayer insulating film 105, the material of the reflecting section 113, the ratio of the area of the reflecting surface 140 to the area of the pixel region PR Depends on. Here, the reflectance of the reflective surface 140 (the reflectance is determined by the material of the reflective portion 113 and the material of the interlayer insulating film 105) is R 0, and one pixel on a surface parallel to the first surface 120 is used. When the ratio of the area of the reflective surface 140 in one pixel region PR to the area of the region PR is S, the reflectance R 2 = R 0 · S is obtained.
したがって、式（２）を満たせば、反射構造部ＲＳの反射率Ｒをゼロより大きくすることができる。 Therefore, if Expression (2) is satisfied, the reflectance R of the reflective structure portion RS can be made larger than zero.
Ｒ２＝Ｒ０・Ｓ＞０．２５ ・・・式（２）
反射部１１３をアルミニウムで形成し、層間絶縁膜１０５をシリコン酸化物で形成する場合、反射部１１３と層間絶縁膜１０５との界面、即ち反射面１４０における反射率Ｒ０は約９０％である。この場合、第１面１２０に対して平行な面における、１つの画素領域ＰＲの面積に対する１つの画素領域ＰＲにおける反射面１４０の面積の比率を２７．８％以上とすれば、（式２）を満たすことができる。その結果、反射構造部ＲＳの反射率Ｒがゼロより大きくなり、感度を向上させることができる。
R 2 = R 0 · S> 0.25 Formula (2)
When the reflecting portion 113 is formed of aluminum and the interlayer insulating film 105 is formed of silicon oxide, the reflectivity R 0 at the interface between the reflecting portion 113 and the interlayer insulating film 105, that is, the reflecting surface 140 is about 90%. In this case, if the ratio of the area of the reflective surface 140 in one pixel region PR to the area of one pixel region PR in a plane parallel to the first surface 120 is 27.8% or more, (Expression 2) Can be met. As a result, the reflectance R of the reflective structure RS becomes larger than zero, and the sensitivity can be improved.
以上のように、第１面１２０に反射防止層１１４を設けることにより、第１面１２０と反射面１４０との間での多重反射を低減して感度を向上させることができる。また、多重反射の低減により感度の不均一性を低減することができる。 As described above, by providing the antireflection layer 114 on the first surface 120, it is possible to reduce the multiple reflection between the first surface 120 and the reflection surface 140 and improve the sensitivity. Also, sensitivity non-uniformity can be reduced by reducing multiple reflections.
上記の例では、半導体層１０１の厚さが３μｍであったが、半導体層１０１の厚さは、例えば２μｍ以上でありうる。反射部１１３の反射面１４０の形状は、それに対応する光電変換部１０２に光が集光されるように凹面形状にされうる。上記の例では、反射部１１３は、第１面１２０に最も近い第１配線層に設けられているが、反射部は、他の配線層に設けられてもよい。また、反射部は、配線を目的とする層以外の層に設けられてもよい。この場合、反射部を形成する材料を自由に選ぶことができるため、反射率を向上させるために有利である。反射部を形成する材料の主成分として、アルミニウム、銅およびタングステン以外の材料を用いてもよい。また、反射部を複数の誘電体膜で形成してもよい。また、反射部を真空または気体が充填された空間で形成してもよい。また、マイクロレンズの焦点位置を第１面１２０と反射部１１３との間にすることにより、反射部１１３によって反射された光の広がりを抑制することができる。これにより、反射部１１３によって反射された光が光電変換部１０２に戻される割合を高くすることができ、感度を向上させることができる。また、第２面１２１にも反射防止層を設けてもよく、これにより半導体層１０１に入射する光の量を増加させることができる。 In the above example, the thickness of the semiconductor layer 101 is 3 μm, but the thickness of the semiconductor layer 101 may be 2 μm or more, for example. The shape of the reflection surface 140 of the reflection unit 113 may be a concave shape so that light is condensed on the corresponding photoelectric conversion unit 102. In the above example, the reflection portion 113 is provided in the first wiring layer closest to the first surface 120, but the reflection portion may be provided in another wiring layer. Moreover, the reflection part may be provided in a layer other than the layer intended for wiring. In this case, since the material which forms a reflection part can be selected freely, it is advantageous in order to improve a reflectance. Materials other than aluminum, copper, and tungsten may be used as the main component of the material that forms the reflective portion. Further, the reflection part may be formed of a plurality of dielectric films. Moreover, you may form a reflection part in the space filled with vacuum or gas. In addition, by setting the focal position of the microlens between the first surface 120 and the reflecting portion 113, the spread of light reflected by the reflecting portion 113 can be suppressed. Thereby, the ratio by which the light reflected by the reflection part 113 is returned to the photoelectric conversion part 102 can be made high, and a sensitivity can be improved. Further, an antireflection layer may be provided also on the second surface 121, whereby the amount of light incident on the semiconductor layer 101 can be increased.
図１Ｂを参照しながら他の細部について説明する。第２の誘電体膜１１４２はゲート電極１０４と層間絶縁膜１０５との間に位置する部分を有しうる。また、第１の誘電体膜１１４１はゲート電極１０４と層間絶縁膜１０５との間に位置する部分を有しうる。各誘電体膜のゲート電極１０４と層間絶縁膜１０５との間に位置する部分はゲート電極１０４の表面での光の反射を低減しうる。各誘電体膜のゲート電極１０４と層間絶縁膜１０５との間に位置する部分と、各誘電体膜の光電変換部１０２を覆う部分とで、厚みが異なっていてもよい。また、第１の誘電体膜１１４１はゲート電極１０４と半導体層１０１との間に位置する部分を有していてもよい。この部分がゲート絶縁膜として機能しうる。第１の誘電体膜１１４１を、ゲート電極１０４と層間絶縁膜１０５との間に位置する部分と、ゲート電極１０４と半導体層１０１との間に位置する部分と、を有するように、ゲート電極１０４の形成の前後に形成することができる。 Other details will be described with reference to FIG. 1B. The second dielectric film 1142 can have a portion located between the gate electrode 104 and the interlayer insulating film 105. Further, the first dielectric film 1141 may have a portion located between the gate electrode 104 and the interlayer insulating film 105. A portion of each dielectric film located between the gate electrode 104 and the interlayer insulating film 105 can reduce light reflection on the surface of the gate electrode 104. The thickness may be different between a portion of each dielectric film positioned between the gate electrode 104 and the interlayer insulating film 105 and a portion of each dielectric film covering the photoelectric conversion unit 102. In addition, the first dielectric film 1141 may have a portion located between the gate electrode 104 and the semiconductor layer 101. This portion can function as a gate insulating film. The gate electrode 104 has a first dielectric film 1141 having a portion located between the gate electrode 104 and the interlayer insulating film 105 and a portion located between the gate electrode 104 and the semiconductor layer 101. It can be formed before and after the formation.
図１Ｂには素子分離部１０３を構成する絶縁体１０３１が例示されている。ここでは、絶縁体１０３１は第１面１２０から突出している。典型的な素子分離部１０３に設けられる絶縁体１０３１はシリコン酸化物である。第２の誘電体膜１１４２は絶縁体１０３１と層間絶縁膜１０５との間に位置する部分を有しうる。また、第１の誘電体膜１１４１は絶縁体１０３１と層間絶縁膜１０５との間に位置する部分を有しうる。各誘電体膜の絶縁体１０３１と層間絶縁膜１０５との間に位置する部分は半導体層１０１の第１面１２０での光の反射を低減しうる。とりわけ、素子分離部１０３の絶縁体１０３１が第１面１２０から突出している場合には、反射面１４０と第１面１２０との間の光の干渉成分を絶縁体１０３１の近傍で低減することで、感度のむらを低減することができる。絶縁体１０３１が複数の画素領域に渡って周期的な凹凸構造を成すことで、感度のむらがより低減される。 FIG. 1B illustrates an insulator 1031 that constitutes the element isolation portion 103. Here, the insulator 1031 protrudes from the first surface 120. An insulator 1031 provided in a typical element isolation portion 103 is silicon oxide. The second dielectric film 1142 can have a portion located between the insulator 1031 and the interlayer insulating film 105. Further, the first dielectric film 1141 may have a portion located between the insulator 1031 and the interlayer insulating film 105. A portion of each dielectric film located between the insulator 1031 and the interlayer insulating film 105 can reduce light reflection on the first surface 120 of the semiconductor layer 101. In particular, when the insulator 1031 of the element isolation portion 103 protrudes from the first surface 120, the light interference component between the reflective surface 140 and the first surface 120 is reduced in the vicinity of the insulator 1031. Unevenness of sensitivity can be reduced. The insulator 1031 forms a periodic concavo-convex structure over a plurality of pixel regions, whereby unevenness in sensitivity is further reduced.
図７を参照しながら本発明の第２実施形態の固体撮像装置２００について説明する。ここで言及しない事項は、第１実施形態に従いうる。第２実施形態では、第１面１２０に接触して配置された反射防止層１１４は、複数のカラーフィルタ１０７ａ、１０７ｂ、１０７ｃにそれぞれ対応する複数の部分を有し、各部分は、対応するカラーフィルタの色に応じた厚さを有する。これにより、各色の画素の感度を向上させることができる。 A solid-state imaging device 200 according to the second embodiment of the present invention will be described with reference to FIG. Matters not mentioned here can follow the first embodiment. In the second embodiment, first surface 120 antireflection layer 1 14 disposed in contact with has a plurality of color filters 107a, 107 b, a plurality of portions respectively corresponding to 107c, each portion corresponding It has a thickness corresponding to the color of the color filter. Thereby, the sensitivity of the pixel of each color can be improved.
第１カラーフィルタ１０７ａ、第２カラーフィルタ１０７ｂ、第３カラーフィルタ１０７ｃがそれぞれ最大透過率を示す波長をλ１、λ２、λ３とし、シリコン窒化物の屈折率をｍとする。反射防止層１１４は、第１カラーフィルタ１０７ａが設けられた画素に設けられた第１部分と、第２カラーフィルタ１０７ｂが設けられた画素に設けられた第２部分と、第３カラーフィルタ１０７ｃが設けられた画素に設けられた第３部分とを含む。第１部分は、第１面１２０の上に形成された厚さ１０ｎｍのシリコン酸化物膜と、その上に形成された厚さλ１／４ｍのシリコン窒化物膜とで構成されうる。第２部分は、第１面１２０の上に形成された厚さ１０ｎｍのシリコン酸化物膜と、その上に形成された厚さλ２／４ｍのシリコン窒化物膜とで構成されうる。第３部分は、第１面１２０の上に形成された厚さ１０ｎｍのシリコン酸化物膜と、その上に形成された厚さλ３／４ｍのシリコン窒化物膜とで構成されうる。 The wavelengths at which the first color filter 107a, the second color filter 107b, and the third color filter 107c exhibit the maximum transmittance are λ 1 , λ 2 , and λ 3, respectively, and the refractive index of silicon nitride is m. Antireflection layer 1 14 includes a first portion where the first color filter 107a is provided in the pixel which is provided, and a second position where the second color filter 107b is provided in the pixel which is provided, the third color filter 107c And a third portion provided in the pixel provided with. The first portion may be composed of a silicon oxide film having a thickness of 10nm was formed on the first surface 120, a silicon nitride film having a thickness of lambda 1 / 4m formed thereon. The second portion may be composed of a silicon oxide film having a thickness of 10nm was formed on the first surface 120, a silicon nitride film having a thickness of lambda 2 / 4m formed thereon. The third portion may be composed of a silicon oxide film having a thickness of 10nm was formed on the first surface 120, a silicon nitride film having a thickness of lambda 3 / 4m formed thereon.
例えば、赤色（Ｒ）、緑色（Ｇ）、青色（Ｂ）の画素のカラーフィルタの最大透過率の波長λ１、λ２、λ３をそれぞれ、６１０ｎｍ、５３０ｎｍ、４５０ｎｍとし、またシリコン窒化物の屈折率ｍを２．０とする。このとき、赤色（Ｒ）、緑色（Ｇ）、青色（Ｂ）の画素の反射防止層２１４（第１部分、第２部分、第３部分）の好ましい厚さは、それぞれ、７６ｎｍ、６６ｎｍ、５６ｎｍである。 For example, the wavelengths λ 1 , λ 2 , and λ 3 of the maximum transmittance of the color filters of the red (R), green (G), and blue (B) pixels are 610 nm, 530 nm, and 450 nm, respectively. The refractive index m is set to 2.0. At this time, preferable thicknesses of the antireflection layers 214 (first portion, second portion, and third portion) of the red (R), green (G), and blue (B) pixels are 76 nm, 66 nm, and 56 nm, respectively. It is.
１０２：光電変換部、１０１：半導体層、１２０：第１面、１２１：第２面、ＷＳ：配線構造、１１３：反射部、１０５：絶縁膜、１１４１：第１の誘電膜、１１４２：第２の誘電膜 102: photoelectric conversion unit, 101: semiconductor layer, 120: first surface, 121: second surface, WS: wiring structure, 113: reflection unit, 105: insulating film, 1141: first dielectric film, 1142: second Dielectric film
Claims (10)
前記配線構造は、第１配線層と、前記第１配線層よりも前記半導体層から離れて配された第２配線層と、前記第１配線層と前記半導体層との間、および、前記第１配線層と前記第２配線層との間に位置する絶縁膜と、を含み、前記複数の光電変換部の各々の間には素子分離部が設けられており、
前記複数の光電変換部のうち前記緑色のカラーフィルタに対応する光電変換部が配置された複数の緑色の画素領域の各々と、前記複数の光電変換部のうち青色のカラーフィルタに対応する光電変換部が配置された複数の青色の画素領域の各々と、において、
前記絶縁膜と前記半導体層との間には、トランジスタのゲート電極が設けられており、前記第１配線層は、前記光電変換部に重なり前記ゲート電極および前記第２配線層に重ならない第１部分と、前記ゲート電極に重なる第４部分とを有し、前記第１部分と前記第４部分とは連続していて、かつ、
前記第２配線層は、前記ゲート電極に重なる第２部分と、前記ゲート電極に重ならない第３部分を有し、かつ、
前記第２面に垂直で前記第１部分、前記第２部分および前記第３部分を含む断面において、前記第１部分の幅が前記第２部分の幅および前記第３部分の幅よりも大きく、前記第１部分のうち前記半導体層に対向する面は前記第１面に平行であり、かつ、
前記第１部分と前記光電変換部との間には前記第１面に接触して配置された第１の誘電体膜と、前記絶縁膜と前記第１の誘電体膜との間に配置された、前記第１の誘電体膜および前記絶縁膜とは屈折率の異なる第２の誘電体膜と、が設けられていて、かつ、
前記第１の誘電体膜および前記第２の誘電体膜は前記ゲート電極と前記絶縁膜との間に位置する部分を有し、
前記複数の緑色の画素領域の間において、前記第１部分と前記光電変換部との間における前記絶縁膜の厚さが、不均一性を有しており、
前記複数の緑色の画素領域の各々において、前記第１部分は前記半導体層を透過した光を前記半導体層に向けて反射する反射面を含み、前記第１の誘電体膜および前記第２の誘電体膜は、前記半導体層を透過して前記反射面で前記半導体層に向けて反射された光が、前記半導体層の前記第１面で反射することを抑制するように構成されており、
前記絶縁膜は、前記半導体層からの距離が前記第１配線層より小さい位置において、前記複数の緑色の画素領域の各々の前記第１部分と前記光電変換部との間から、前記複数の青色の画素領域の各々の前記第１部分と前記光電変換部との間まで延在しており、
前記絶縁膜の一部が、前記複数の緑色の画素領域の各々の前記第１部分と前記複数の青色の画素領域の各々の前記第１部分と、の間に位置し、前記絶縁膜の前記一部が前記素子分離部に重なることを特徴とする固体撮像装置。 A semiconductor layer having a plurality of photoelectric conversion portions; a wiring structure disposed on a first surface side of the semiconductor layer; a plurality of microlenses disposed on a second surface side of the semiconductor layer; A solid-state imaging device having a color filter layer including a green color filter and a blue color filter disposed between a microlens and the semiconductor layer,
The wiring structure includes a first wiring layer, a second wiring layer disposed farther from the semiconductor layer than the first wiring layer, between the first wiring layer and the semiconductor layer, and the first wiring layer. An insulating film positioned between one wiring layer and the second wiring layer, and an element isolation portion is provided between each of the plurality of photoelectric conversion portions,
Each of a plurality of green pixel regions in which a photoelectric conversion unit corresponding to the green color filter among the plurality of photoelectric conversion units is disposed, and a photoelectric conversion corresponding to a blue color filter among the plurality of photoelectric conversion units In each of the plurality of blue pixel regions in which the portion is disposed,
A gate electrode of a transistor is provided between the insulating film and the semiconductor layer, and the first wiring layer overlaps the photoelectric conversion unit and does not overlap the gate electrode and the second wiring layer. And a fourth portion overlapping the gate electrode, the first portion and the fourth portion are continuous, and
The second wiring layer has a second portion overlapping the gate electrode and a third portion not overlapping the gate electrode; and
In a cross section perpendicular to the second surface and including the first portion, the second portion, and the third portion, the width of the first portion is larger than the width of the second portion and the width of the third portion, The surface of the first portion that faces the semiconductor layer is parallel to the first surface, and
Between the first portion and the photoelectric conversion unit, a first dielectric film disposed in contact with the first surface, and disposed between the insulating film and the first dielectric film. A second dielectric film having a refractive index different from that of the first dielectric film and the insulating film, and
The first dielectric film and the second dielectric film have a portion located between the gate electrode and the insulating film;
Between the plurality of green pixel regions, the thickness of the insulating film between the first portion and the photoelectric conversion unit has non-uniformity,
In each of the plurality of green pixel regions, the first portion includes a reflective surface that reflects light transmitted through the semiconductor layer toward the semiconductor layer, and the first dielectric film and the second dielectric film body layer, the semiconductor layer transparent to light reflected toward the semiconductor layer in the reflective surface, is configured to suppress the reflection at the first surface of the front Symbol semiconductor layer,
The insulating film is located between the first portion of each of the plurality of green pixel regions and the photoelectric conversion unit at a position where the distance from the semiconductor layer is smaller than the first wiring layer. Extending between the first portion of each of the pixel regions and the photoelectric conversion unit,
A portion of the insulating film is located between the first portion of each of the plurality of green pixel regions and the first portion of each of the plurality of blue pixel regions; A solid-state imaging device, wherein part of the solid-state imaging device overlaps the element isolation portion.
Ｒ０・Ｓ＞０．２５
を満たすことを特徴とする請求項１に記載の固体撮像装置。 The wiring structure, the reflectance of the first wiring layer R 0, the ratio of the area of the first wiring layer to the one pixel region of the first surface and a plane parallel when the S,
R 0 · S> 0.25
The solid-state imaging device according to claim 1, wherein:
前記第１の誘電体膜および第２の誘電体膜は前記絶縁膜よりも薄い、
ことを特徴とする請求項１または２に記載の固体撮像装置。 The second dielectric film is thicker than the first dielectric film,
The first dielectric film and the second dielectric film are thinner than the insulating film;
The solid-state imaging device according to claim 1 or 2.
ことを特徴とする請求項１乃至３のいずれか１項に記載の固体撮像装置。 The fourth portion overlaps the second wiring layer;
The solid-state imaging device according to any one of claims 1 to 3.
ことを特徴とする請求項１乃至５のいずれか１項に記載の固体撮像装置。 The element isolation portion includes an insulator, and the second dielectric film has a portion located between the insulator and the insulating film of the element isolation portion.
The solid-state imaging device according to claim 1, wherein the solid-state imaging device is provided.
前記第２の誘電体膜はシリコン窒化物である、
ことを特徴とする請求項１乃至６のいずれか１項に記載の固体撮像装置。 The first dielectric film and the insulating film are silicon oxide;
The second dielectric film is silicon nitride;
The solid-state imaging device according to claim 1, wherein the solid-state imaging device is provided.
前記カラーフィルタ層は赤色のカラーフィルタを含む、
ことを特徴とする請求項１乃至７のいずれか１項に記載の固体撮像装置。 The semiconductor layer has a thickness of 2 μm or more,
The color filter layer includes a red color filter;
The solid-state imaging device according to claim 1, wherein
ことを特徴とする請求項１乃至８のいずれか１項に記載の固体撮像装置。 The insulating film is in contact with the second dielectric film and the first wiring layer;
The solid-state imaging device according to claim 1, wherein the solid-state imaging device is provided.
ことを特徴とする請求項１乃至９のいずれか１項に記載の固体撮像装置。 The second dielectric film has a thickness corresponding to the color of the corresponding color filter.
The solid-state imaging device according to any one of claims 1 to 9.
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| US8299554B2 (en) * | 2009-08-31 | 2012-10-30 | International Business Machines Corporation | Image sensor, method and design structure including non-planar reflector |
| JP5538811B2 (en) * | 2009-10-21 | 2014-07-02 | キヤノン株式会社 | Solid-state image sensor |
| JP2011040774A (en) * | 2010-10-06 | 2011-02-24 | Sony Corp | Solid-state imaging element, camera module, and electronic apparatus module |
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