JP2009146957A

JP2009146957A - Solid-state imaging apparatus, and manufacturing method of solid-state imaging apparatus

Info

Publication number: JP2009146957A
Application number: JP2007320267A
Authority: JP
Inventors: Hitoshi Kuriyama; 仁志栗山; Ryohei Miyagawa; 良平宮川; Hiroyuki Doi; 博之土井
Original assignee: Panasonic Corp
Current assignee: Panasonic Corp
Priority date: 2007-12-12
Filing date: 2007-12-12
Publication date: 2009-07-02

Abstract

<P>PROBLEM TO BE SOLVED: To improve a light convergence rate while enhancing uniformity of the amount of incident light to each pixel in a light receiving pixel region, and also to effectively prevent erroneous incident light from being incident on a light shield pixel region constituting optical black generating a black reference signal. <P>SOLUTION: In a solid-state imaging apparatus, the film thickness of a protective film 31 in the light receiving pixel region 3 can be made constant by providing a boundary pixel region 2 between the light shield pixel region 1 and light receiving pixel region 3, so pixel characteristics of a light receiving pixel region 3 disposed closest to the light shield pixel region 1 can be matched with the same characteristics as respective pixel characteristics in other light receiving pixel regions 3, and erroneous light can be effectively prevented from being incident on photoelectric converting elements in the light shield pixel region 1 forming an optical black region on which black is based. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

本発明は、光電変換素子を用いて撮像する固体撮像装置及びその製造方法に関するものである。 The present invention relates to a solid-state imaging device that captures an image using a photoelectric conversion element and a manufacturing method thereof.

従来から、ＣＣＤイメージセンサまたはＣＭＯＳイメージセンサ等の固体撮像装置では、二次元に配列した受光画素領域の光電変換素子で得られた撮像信号の輝度を調整するため、光電変換素子への光を遮る遮光膜を備えた遮光画素領域を設け、その遮光画素領域からの信号を輝度の基準信号として使用している。この基準信号は黒基準を提供するものであり、この受光しないで黒基準信号を生成する遮光画素領域は、オプティカルブラックと呼ばれている。 Conventionally, in a solid-state imaging device such as a CCD image sensor or a CMOS image sensor, light to the photoelectric conversion element is blocked in order to adjust the luminance of the imaging signal obtained by the photoelectric conversion element in the light receiving pixel region arranged in two dimensions. A light-shielded pixel region having a light-shielding film is provided, and a signal from the light-shielded pixel region is used as a luminance reference signal. This reference signal provides a black reference, and the light-shielded pixel region that generates the black reference signal without receiving light is called optical black.

このオプティカルブラックを構成する遮光画素領域の光電変換素子は、受光画素領域の光電変換素子と全く同一の特性を持つことが望ましいため、受光画素領域と遮光画素領域は可能な限り接近させて配置される。 It is desirable that the photoelectric conversion elements in the light-shielding pixel area constituting the optical black have exactly the same characteristics as the photoelectric conversion elements in the light-receiving pixel area. Therefore, the light-receiving pixel area and the light-shielding pixel area are arranged as close as possible. The

また、固体撮像装置においても、更なる小型化等の要求の為に画素領域の微細化も進展し、その結果、光電変換素子の面積の減少による感度低下が生じている。この感度低下に対して、光電変換素子上に設けられた保護膜が平坦化された面上にマイクロレンズを形成し、光電変換素子に集光して感度の低下を抑制する技術が知られているが、更なる集光を図る為にマイクロレンズと光電変換素子との間に、隣接する層と異なる屈折率を有する膜から構成される層内レンズを設ける構造も提案されている。 Also in the solid-state imaging device, the pixel area has been miniaturized due to a demand for further miniaturization and the like, and as a result, the sensitivity is lowered due to the reduction in the area of the photoelectric conversion element. A technology is known in which a microlens is formed on the surface on which the protective film provided on the photoelectric conversion element is flattened, and is focused on the photoelectric conversion element to suppress the decrease in sensitivity. However, a structure in which an in-layer lens composed of a film having a refractive index different from that of an adjacent layer is provided between the microlens and the photoelectric conversion element for further condensing is proposed.

以下、従来のマイクロレンズと凸型層内レンズを有する固体撮像装置の構成について図７を参照して簡単に説明する。図７は従来のマイクロレンズと凸型層内レンズを有する固体撮像装置を示す断面図である。 Hereinafter, the configuration of a conventional solid-state imaging device having a microlens and a convex in-layer lens will be briefly described with reference to FIG. FIG. 7 is a cross-sectional view showing a solid-state imaging device having a conventional microlens and a convex in-layer lens.

図７において、１は遮光画素領域、３は受光画素領域、４は光電変換素子、１０４は第一メタル配線層、１０５は第二メタル配線層、１０６は第三メタル配線層、１０７は保護膜、１０８は層内レンズ、１０９は平坦化膜、１１０はカラーフィルタ層、１１１はマイクロレンズである。従来の固体撮像装置は、図７に示すように、遮光画素領域１と受光画素領域３から構成され、それぞれ、マイクロレンズ１１１,層内レンズ１０８,光電変換素子及び複数層のメタル配線層を備え、遮光画素領域１の層内レンズ１０８直下には、保護膜１０７を介して遮光膜として第三メタル配線層１０６を形成している。このように層内レンズ１０８を設けることにより、光電変換素子までの距離を短縮することができ、感度低下をもたらすことなく集光効率を高めることができる（例えば、特許文献１参照）。
特開２００７−１３０６１号公報 In FIG. 7, 1 is a light-shielding pixel region, 3 is a light-receiving pixel region, 4 is a photoelectric conversion element, 104 is a first metal wiring layer, 105 is a second metal wiring layer, 106 is a third metal wiring layer, and 107 is a protective film. , 108 are intra-layer lenses, 109 is a planarizing film, 110 is a color filter layer, and 111 is a microlens. As shown in FIG. 7, the conventional solid-state imaging device includes a light-shielding pixel region 1 and a light-receiving pixel region 3, and includes a microlens 111, an intralayer lens 108, a photoelectric conversion element, and a plurality of metal wiring layers. A third metal wiring layer 106 is formed as a light shielding film via a protective film 107 immediately below the inner lens 108 in the light shielding pixel region 1. By providing the in-layer lens 108 in this manner, the distance to the photoelectric conversion element can be shortened, and the light collection efficiency can be increased without causing a decrease in sensitivity (for example, see Patent Document 1).
JP 2007-13061 A

しかしながら、図７に示すような受光画素領域３と遮光画素領域１を隣合わせに配置した構造では、遮光画素領域１の遮光膜である第三のメタル配線１０６の膜厚により生じた段差は平坦化されていないために、段差に隣接して配置された受光画素に設けられる層内レンズ１０８は、この段差から十分に離れた受光画素に設けられる層内レンズ１０８に対して、段差による保護膜１０７の膜厚変動が生じるために、層内レンズ１０８と保護膜１０７を合わせた高さが変動したり、層内レンズ１０８が傾斜したりして、結果的にこの画素の集光率や光学特性が変動し、光電変換素子４への入射光量が変動する。また、第三メタル配線層１０６の段差部の側面によって反射された入射光が遮光画素領域１に隣接した受光画素領域３へ入射され、不正な反射光を受光することによる感度の変動も加わり、遮光画素領域３に隣接した受光画素からの撮像信号は特性変動を生じる。その結果、受光画素領域３の全画素に渡って均一な撮像特性を得られない装置となる。 However, in the structure in which the light-receiving pixel region 3 and the light-shielding pixel region 1 are arranged next to each other as shown in FIG. 7, the level difference caused by the film thickness of the third metal wiring 106 that is the light-shielding film of the light-shielding pixel region 1 is flattened. Therefore, the in-layer lens 108 provided in the light-receiving pixel disposed adjacent to the step is not the same as the in-layer lens 108 provided in the light-receiving pixel sufficiently away from the step. Therefore, the combined height of the inner lens 108 and the protective film 107 fluctuates, or the inner lens 108 tilts, resulting in the light collection rate and optical characteristics of the pixel. Varies, and the amount of incident light on the photoelectric conversion element 4 varies. In addition, incident light reflected by the side surface of the stepped portion of the third metal wiring layer 106 is incident on the light receiving pixel region 3 adjacent to the light shielding pixel region 1, and fluctuations in sensitivity due to receiving illegal reflected light are added, An imaging signal from a light receiving pixel adjacent to the light shielding pixel region 3 causes a characteristic variation. As a result, the device cannot obtain uniform imaging characteristics over all pixels in the light receiving pixel region 3.

また、微細化が進められたＣＭＯＳイメージセンサの場合、画素間を接続する配線は多層配線を用いることが多く、層内レンズと光電変換素子の距離は大きくなり、遮光画素に隣接して配置された受光画素に入射した光は、一部が配線膜による回折や反射によって迷光となり、隣接した遮光画素に入射することで、遮光画素によって生成される黒基準信号には不正な光を受けて生成された信号を含むことになる。特に、長波長光の場合、入射深度が大きいため、遮光画素へ到達する割合が多くなる。 In addition, in the case of a CMOS image sensor that has been miniaturized, a multilayer wiring is often used for wiring between pixels, and the distance between the inner lens and the photoelectric conversion element becomes large, and the pixel is disposed adjacent to the light shielding pixel. Part of the light incident on the light-receiving pixels becomes stray light due to diffraction and reflection by the wiring film, and is incident on the adjacent light-shielding pixels, so that the black reference signal generated by the light-shielded pixels receives illegal light and is generated Signal will be included. In particular, in the case of long-wavelength light, since the incident depth is large, the ratio of reaching the light-shielded pixels increases.

そこで本発明は、受光画素領域の各画素への入射光量の均一性を高めながら集光率も向上でき、かつ黒基準信号を生成するオプティカルブラックを構成する遮光画素領域への不正入射光を有効に防止することを目的とする。 Accordingly, the present invention can improve the light collection rate while improving the uniformity of the amount of light incident on each pixel in the light receiving pixel region, and can effectively use the illegal incident light to the light shielding pixel region constituting the optical black that generates the black reference signal. The purpose is to prevent.

上述の目的を達成するために、本発明の固体撮像装置は、主面に光電変換素子が形成され、受光画素領域と境界画素領域と遮光画素領域とを備えた半導体基板と、前記半導体基板上に形成された層間絶縁膜と、前記層間絶縁膜上に形成された配線層と、前記受光画素領域における前記層間絶縁膜上に形成された第１の層内レンズと、前記境界画素領域における前記層間絶縁膜上に形成された第１の入射光制限膜と、前記遮光画素領域における前記層間絶縁膜上に形成された遮光膜とを備え、前記境界画素領域は、受光画素領域と前記遮光画素領域の間に形成されていることを特徴とする。 In order to achieve the above-described object, a solid-state imaging device according to the present invention includes a semiconductor substrate having a photoelectric conversion element formed on a main surface and having a light-receiving pixel region, a boundary pixel region, and a light-shielding pixel region; An interlayer insulating film formed on the interlayer insulating film, a wiring layer formed on the interlayer insulating film, a first intra-layer lens formed on the interlayer insulating film in the light receiving pixel region, and the boundary pixel region A first incident light limiting film formed on the interlayer insulating film; and a light shielding film formed on the interlayer insulating film in the light shielding pixel region, wherein the boundary pixel region includes a light receiving pixel region and the light shielding pixel. It is characterized by being formed between the regions.

また、前記境界画素領域における前記層間絶縁膜上にさらに第２の層内レンズを備えることを特徴とする。
また、前記遮光画素領域における前記層間絶縁膜上にさらに第２の入射光制限膜を備えることを特徴とする。 Further, a second in-layer lens is further provided on the interlayer insulating film in the boundary pixel region.
In addition, a second incident light limiting film is further provided on the interlayer insulating film in the light-shielding pixel region.

また、前記配線層と前記第１の入射光制限膜及び第２の入射光制限膜は同一の材料であることを特徴とする。
また、前記受光画素領域における前記層間絶縁膜上にカラーフィルタを備えることを特徴とする。 Further, the wiring layer, the first incident light limiting film, and the second incident light limiting film are made of the same material.
Further, a color filter is provided on the interlayer insulating film in the light receiving pixel region.

また、前記受光画素領域における前記層間絶縁膜上にマイクロレンズを備えることを特徴とする。
また、外部と接続するためのコンタクトパッドをさらに備え、前記遮光膜と前記コンタクトパッドは同一の材料で形成されていることを特徴とする。 Moreover, a microlens is provided on the interlayer insulating film in the light receiving pixel region.
In addition, a contact pad for connecting to the outside is further provided, and the light shielding film and the contact pad are formed of the same material.

また、前記第１の層内レンズの底面は前記遮光膜の上面よりも低いことを特徴とする。
さらに、受光画素領域と境界画素領域と遮光画素領域とを備えた半導体基板に光電変換素子を形成する工程と、前記半導体基板上に層間絶縁膜を形成する工程と、前記層間絶縁膜上に配線層を形成する工程と、前記境界画素領域における前記層間絶縁膜上に入射光制限膜を形成する工程と、前記遮光画素領域における前記層間絶縁膜上に遮光膜を形成する工程と、前記受光画素領域における前記層間絶縁膜上に層内レンズを形成する工程とからなることを特徴とする。 The bottom surface of the first intra-layer lens is lower than the top surface of the light shielding film.
A step of forming a photoelectric conversion element on a semiconductor substrate having a light-receiving pixel region, a boundary pixel region, and a light-shielding pixel region; a step of forming an interlayer insulating film on the semiconductor substrate; and a wiring on the interlayer insulating film Forming a layer; forming an incident light limiting film on the interlayer insulating film in the boundary pixel region; forming a light shielding film on the interlayer insulating film in the light shielding pixel region; and the light receiving pixel. And forming an intra-layer lens on the interlayer insulating film in the region.

また、前記配線層の形成工程と前記入射光制限膜の形成工程とを同時に行うことを特徴とする。
以上により、受光画素領域の各画素への入射光量の均一性を高めながら集光率も向上でき、かつ黒基準信号を生成するオプティカルブラックを構成する遮光画素領域への不正入射光を防止することができる。 Further, the wiring layer forming step and the incident light limiting film forming step are performed simultaneously.
As described above, it is possible to improve the light collection rate while improving the uniformity of the amount of light incident on each pixel in the light receiving pixel region, and to prevent illegal incident light to the light shielding pixel region constituting the optical black that generates the black reference signal. Can do.

本発明の固体撮像装置によれば、遮光画素領域と受光画素領域の間に境界画素領域を設けることによって、受光画素領域における保護膜の膜厚を一定にすることができるために遮光画素領域に対して最も近傍に配置される受光画素の画素特性を他の受光画素の各画素特性と同一な特性に合わせることが出来ると共に、黒基準となるオプティカルブラック領域を形成する遮光画素領域の光電変換素子への不正入射光を有効に防止することができる。 According to the solid-state imaging device of the present invention, by providing the boundary pixel region between the light-shielding pixel region and the light-receiving pixel region, the thickness of the protective film in the light-receiving pixel region can be made constant. On the other hand, the photoelectric conversion element of the light-shielding pixel region which can match the pixel characteristic of the light receiving pixel arranged closest to the pixel characteristic of each of the other light receiving pixels and forms an optical black region serving as a black reference It is possible to effectively prevent unauthorized incident light on the screen.

以下、添付図面を参照して本発明の実施形態について詳細に説明する。ただし、本実施形態において例示される構成部品の寸法、材質、形状、それらの相対配置などは、本発明が適用される装置の構成や各種条件により適宜変更されるべきものであり、本発明がそれらの例示に限定されるものではない。 Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components exemplified in the present embodiment should be changed as appropriate according to the configuration of the apparatus to which the present invention is applied and various conditions. It is not limited to those examples.

まず、図１，図２を用いて、本発明の固体撮像装置の構成について説明する。
図１は、本発明の固体撮像装置の構成を示す断面図であって、撮像画素を有する固体撮像装置の一部を示しており、１は遮光画素領域、２は境界画素領域、３は受光画素領域、４は入射光を電荷信号に変換する光電変換素子、１１は第一層間絶縁膜、１２は第二層間絶縁膜、１３は第三層間絶縁膜、１４は第四層間絶縁膜、２１は電荷信号を画像信号として伝達する第一メタル配線層、２２は電荷信号を画像信号として伝達する第二メタル配線層、２３は電荷信号を画像信号として伝達する第三メタル配線層、２４は入射光制限膜、２５は遮光膜、３１は保護膜、３２は層内レンズ，３３は第一平坦化膜、３４はカラーフィルタ膜、３５は第二平坦化膜、３６はマイクロレンズである。 First, the configuration of the solid-state imaging device of the present invention will be described with reference to FIGS.
FIG. 1 is a cross-sectional view showing a configuration of a solid-state imaging device according to the present invention, which shows a part of a solid-state imaging device having imaging pixels, where 1 is a light-shielding pixel region, 2 is a boundary pixel region, and 3 is light-receiving Pixel region, 4 is a photoelectric conversion element that converts incident light into a charge signal, 11 is a first interlayer insulating film, 12 is a second interlayer insulating film, 13 is a third interlayer insulating film, 14 is a fourth interlayer insulating film, 21 is a first metal wiring layer that transmits a charge signal as an image signal, 22 is a second metal wiring layer that transmits a charge signal as an image signal, 23 is a third metal wiring layer that transmits a charge signal as an image signal, and 24 An incident light limiting film, 25 is a light shielding film, 31 is a protective film, 32 is an inner lens, 33 is a first planarizing film, 34 is a color filter film, 35 is a second planarizing film, and 36 is a microlens.

図１に示すように、遮光画素領域１の光電変換素子４への入射光を遮光するために遮光膜２５が第一層間絶縁膜１１、第二層間絶縁膜１２、第三層間絶縁膜１３及び第四層間絶縁膜１４を介して設けられており、第三メタル配線層２３の一部が入射光制限膜２４として設けられている。境界画素領域２には遮光膜２５が形成されておらず、保護膜３１上に層内レンズ３２が設置されてその下部には入射光を減衰させる入射光制限膜２４が設けられている。受光画素領域３には光電変換素子４まで十分な入射光が到達できるように第一層間絶縁膜１１、第二層間絶縁膜１２、第三層間絶縁膜１３、第四層間絶縁膜１４及び保護膜２５を介して層内レンズ３２が設けられている。 As shown in FIG. 1, the light shielding film 25 includes a first interlayer insulating film 11, a second interlayer insulating film 12, and a third interlayer insulating film 13 in order to shield incident light on the photoelectric conversion element 4 in the light shielding pixel region 1. In addition, a part of the third metal wiring layer 23 is provided as the incident light limiting film 24 via the fourth interlayer insulating film 14. The light shielding film 25 is not formed in the boundary pixel region 2, the intralayer lens 32 is provided on the protective film 31, and the incident light limiting film 24 that attenuates the incident light is provided below the inner lens 32. The first interlayer insulating film 11, the second interlayer insulating film 12, the third interlayer insulating film 13, the fourth interlayer insulating film 14, and the protection so that sufficient incident light can reach the photoelectric conversion element 4 in the light receiving pixel region 3. An in-layer lens 32 is provided via the film 25.

ここで、遮光画素領域１の遮光膜２５にはＡｌを主体とした金属膜が用いられ、第一メタル配線層２１、第二メタル配線層２２、第三メタル配線層２３の配線膜及び入射光制限膜２４にはＣｕを主体とした金属膜が用いられている。また、遮光膜２５はここでは図示していないが、外部との接続をするために使用されるＡｌを主体としたコンタクトパッド膜と同一の金属膜で形成することもでき、同時に形成される。 Here, a metal film mainly composed of Al is used for the light shielding film 25 in the light shielding pixel region 1, and the wiring film and incident light of the first metal wiring layer 21, the second metal wiring layer 22, and the third metal wiring layer 23 are used. The limiting film 24 is a metal film mainly composed of Cu. Further, although not shown here, the light shielding film 25 can be formed of the same metal film as the contact pad film mainly composed of Al used for connection to the outside, and is formed at the same time.

一般にＣｕ膜は大面積で形成された場合、ディッシングと呼ばれる現象で形成領域の中心部では周辺に対して薄膜化するが、遮光画素領域１及び境界画素領域２に、入射光を減衰させる目的で配置されている入射光制限膜２４は、境界画素領域２に設定される画素数が１乃至２列のみである為、ディッシングによる薄膜化は殆どなく、十分な入射光を減衰させる効果がある。一方、大きな領域を必要とする遮光画素領域１において生じるディッシングは、上部に遮光膜２５が存在するため問題は無い。本実施形態では遮光画素領域１に渡って入射光制限膜２４を配置しているが一部隙間を形成することも可能で、また、全くメタル配線層による入射光制限膜２４を遮光画素領域１に設けない構成も可能である。 In general, when a Cu film is formed in a large area, it is thinned with respect to the periphery at the center of the formation region due to a phenomenon called dishing. However, for the purpose of attenuating incident light in the light-shielding pixel region 1 and the boundary pixel region 2. Since the incident light limiting film 24 arranged has only one or two columns in the boundary pixel region 2, there is almost no thinning due to dishing, and there is an effect of sufficiently attenuating incident light. On the other hand, dishing that occurs in the light-shielding pixel region 1 that requires a large region is not problematic because the light-shielding film 25 exists on the top. In the present embodiment, the incident light limiting film 24 is disposed over the light shielding pixel region 1, but it is also possible to form a part of the gap, and the incident light limiting film 24 formed by a metal wiring layer is completely used as the light shielding pixel region 1. It is possible to adopt a configuration not provided in

また、図２は本発明の固体撮像装置の構成を示す平面図で、遮光膜２５と層内レンズ３２の構成がわかるようにした平面であり、遮光画素領域１と受光画素領域３の間に設けられた境界画素領域２を示している。遮光画素領域１には遮光膜２５が配置されており、受光画素領域３と境界画素領域２には層内レンズ３２が設けられている。この実施形態では、境界画素領域２は１画素分を設けているが、２画素以上の画素列を設けることも可能である。遮光画素領域１及び境界画素領域２に入射光を減衰させる目的で配置されている入射光制限膜２４は、受光画素領域３の層内レンズ３２の端部まで配置させておくことで、遮光画素領域１に対する不正入射光の防止には十分効果がある。また、入射光を減衰させる目的で配置されている入射光制限膜２４は、Ｃｕ膜にて大面積で形成された場合はディッシングと呼ばれる現象で形成領域の中心部では周辺に対して薄膜化するが、境界画素領域２に設定される画素数は１乃至２列のみである為、ディッシングによる薄膜化は殆どなく十分な入射光を減衰させる効果がある。一方、大きな領域を必要とする遮光画素領域１において生じるディッシングは、上部に遮光膜２５が存在するため問題は無い。 FIG. 2 is a plan view showing the configuration of the solid-state imaging device of the present invention, which is a plane in which the configurations of the light-shielding film 25 and the inner lens 32 are understood, and is between the light-shielding pixel region 1 and the light-receiving pixel region 3. A provided boundary pixel region 2 is shown. A light shielding film 25 is disposed in the light shielding pixel region 1, and an intralayer lens 32 is provided in the light receiving pixel region 3 and the boundary pixel region 2. In this embodiment, the boundary pixel region 2 is provided for one pixel, but it is also possible to provide a pixel column of two or more pixels. The incident light limiting film 24 disposed for the purpose of attenuating incident light in the light-shielding pixel region 1 and the boundary pixel region 2 is disposed up to the end of the in-layer lens 32 in the light-receiving pixel region 3. This is sufficiently effective in preventing illegally incident light on the region 1. In addition, the incident light limiting film 24 arranged for the purpose of attenuating incident light is thinned with respect to the periphery at the center of the formation region due to a phenomenon called dishing when formed in a large area with a Cu film. However, since the number of pixels set in the boundary pixel region 2 is only one or two columns, there is almost no thinning by dishing, and there is an effect of attenuating sufficient incident light. On the other hand, dishing that occurs in the light-shielding pixel region 1 that requires a large region is not problematic because the light-shielding film 25 exists on the top.

次に、上述した本発明による固体撮像装置の製造方法について、図３〜図６を用いて説明する。
図３は本発明の固体撮像装置の製造方法における素子領域形成工程を説明する工程断面図、図４は本発明の固体撮像装置の製造方法における遮光膜形成工程を説明する工程断面図、図５は本発明の固体撮像装置の製造方法における層内レンズ形成工程を説明する工程断面図、図６は本発明の固体撮像装置の製造方法におけるカラーフィルタ層形成工程を説明する工程断面図で、図１と対応する部分には同一符号を付す。 Next, the manufacturing method of the solid-state imaging device according to the present invention described above will be described with reference to FIGS.
3 is a process cross-sectional view illustrating a process for forming an element region in the method for manufacturing a solid-state imaging device according to the present invention, FIG. 4 is a process cross-sectional view illustrating a process for forming a light shielding film in the method for manufacturing a solid-state image capturing apparatus according to the present invention. FIG. 6 is a process cross-sectional view illustrating an intra-layer lens forming process in the method for manufacturing a solid-state imaging device of the present invention, and FIG. 6 is a process cross-sectional view illustrating a color filter layer forming process in the method for manufacturing a solid-state image capturing apparatus of the present invention. Parts corresponding to 1 are denoted by the same reference numerals.

まず、図３に示すように、基板上の遮光画素領域１、境界画素領域２及び受光画素領域３に各画素の光電変換素子４が同一に形成され、その上に各画素からの信号電荷を取り出す目的でＣｕ膜を使ったダマシン工法により第一メタル配線層２１、第二メタル配線層２２及び第三メタル配線層２３が第一層間絶縁膜１１、第二層間絶縁膜１２及び第三層間絶縁膜１３を介して形成される。ここで、第三メタル配線層２３は受光画素領域３では配線層として形成され、遮光画素領域１及び境界画素領域２では各画素を覆う領域に渡って入射光制限膜２４として形成される。 First, as shown in FIG. 3, the photoelectric conversion elements 4 of the respective pixels are formed in the same manner in the light-shielding pixel region 1, the boundary pixel region 2, and the light-receiving pixel region 3 on the substrate. For the purpose of taking out, the first metal wiring layer 21, the second metal wiring layer 22 and the third metal wiring layer 23 are formed by the damascene method using a Cu film to form the first interlayer insulating film 11, the second interlayer insulating film 12 and the third interlayer. It is formed through the insulating film 13. Here, the third metal wiring layer 23 is formed as a wiring layer in the light receiving pixel region 3, and is formed as an incident light limiting film 24 over the region covering each pixel in the light shielding pixel region 1 and the boundary pixel region 2.

次に、図４に示すように、第三メタル配線層２３及び入射光制限膜２４の上面に第四層間絶縁膜１４を形成した後に、Ａｌ膜を使用して遮光膜２５を遮光画素領域１を覆う領域に形成すると同時に、外部とのコンタクトパッド電極も形成する。その後、保護膜３１を遮光膜２５よりも薄い膜厚として形成することにより、受光画素領域１と境界画素領域２の保護膜３１の上面を遮光膜２５の上面より低い位置とし、入射光の集光特性を高くする。 Next, as shown in FIG. 4, after the fourth interlayer insulating film 14 is formed on the upper surfaces of the third metal wiring layer 23 and the incident light limiting film 24, the light shielding film 25 is made of the light shielding pixel region 1 using an Al film. At the same time, a contact pad electrode is formed on the outside. Thereafter, the protective film 31 is formed to be thinner than the light shielding film 25, so that the upper surface of the protective film 31 in the light receiving pixel region 1 and the boundary pixel region 2 is positioned lower than the upper surface of the light shielding film 25. Increase optical properties.

そして、図５に示すように、保護膜３１上に層内レンズ３２を境界画素領域２及び受光画素領域３の各画素に対して形成する。その後、第一平坦化膜３３を形成し、遮光膜２５と層内レンズ３２の段差等を平坦化する。 Then, as shown in FIG. 5, an intralayer lens 32 is formed on the protective film 31 for each pixel in the boundary pixel region 2 and the light receiving pixel region 3. Thereafter, a first planarizing film 33 is formed, and a step between the light shielding film 25 and the inner lens 32 is planarized.

そして、図６に示すようにカラーフィルタ層３４を形成し、その平坦化のために第二平坦化膜３５を形成する。カラーフィルタとしては、ＲＧＢの原色フィルタでも、シアン、マゼンタ、イエロー、グリーンの補色フィルタでも、もしくは、カラーフィルタを備えていなくてもよい。カラーフィルタ層３４を備えていない場合は、第二平坦化層３５も備える必要はなく、マイクロレンズ３５を第一平坦化層３３上に形成することができ、固体撮像素子をさらに薄くすることが可能である。 Then, as shown in FIG. 6, a color filter layer 34 is formed, and a second planarizing film 35 is formed for the planarization. As the color filter, RGB primary color filters, cyan, magenta, yellow, green complementary color filters, or no color filter may be provided. When the color filter layer 34 is not provided, it is not necessary to provide the second flattening layer 35, the microlens 35 can be formed on the first flattening layer 33, and the solid-state imaging device can be further thinned. Is possible.

最後に、第二平坦化膜３５上にマイクロレンズ３６を形成し、図１に示す本発明の固体撮像装置を得る。
以上のように本発明の固体撮像装置では、遮光画素領域と受光画素領域の間に境界画素領域を設けることによって、遮光画素領域上に形成された遮光膜端部のみに保護膜の厚み差による傾斜が形成されるため、受光画素領域上では保護膜の膜厚が全面的に一定となり、その上に形成する層内レンズと光電変換素子との距離は一定に保たれる。その結果、各画素の層内レンズの集光特性は全受光画素領域に渡って均一となり、受光画素領域の光電変換素子に対して集光効率の向上を図りながら集光特性の均一化が実現できる。また、遮光画素領域と受光画素領域の間に境界画素領域を設けることによって、黒基準信号を生成するオプティカルブラックを構成する遮光画素領域への不正入射光を有効に防止することができる。 Finally, a microlens 36 is formed on the second planarizing film 35 to obtain the solid-state imaging device of the present invention shown in FIG.
As described above, in the solid-state imaging device according to the present invention, by providing the boundary pixel region between the light-shielding pixel region and the light-receiving pixel region, only the edge of the light-shielding film formed on the light-shielding pixel region is caused by the difference in thickness of the protective film. Since the slope is formed, the film thickness of the protective film is entirely constant over the light receiving pixel region, and the distance between the in-layer lens formed thereon and the photoelectric conversion element is kept constant. As a result, the condensing characteristic of the inner lens of each pixel is uniform over the entire light receiving pixel area, and the light condensing characteristic is made uniform while improving the light condensing efficiency with respect to the photoelectric conversion element in the light receiving pixel area. it can. In addition, by providing a boundary pixel region between the light-shielding pixel region and the light-receiving pixel region, it is possible to effectively prevent illegal incident light on the light-shielding pixel region constituting the optical black that generates the black reference signal.

なお、以上の説明では、本発明の固体撮像装置としてＭＯＳ型イメージセンサを前提としているが、受光面上に配線層を持たないＣＣＤイメージセンサにも同様に適用することができる。
また、上述のような可視光による固体撮像装置に限らず、例えば赤外線等の不可視光による固体撮像装置に対しても、同様に適用することができる。 In the above description, a MOS image sensor is assumed as the solid-state imaging device of the present invention. However, the present invention can be similarly applied to a CCD image sensor having no wiring layer on the light receiving surface.
Further, the present invention is not limited to the above-described solid-state imaging device using visible light, and can be similarly applied to a solid-state imaging device using invisible light such as infrared rays.

また、上記実施形態は層間絶縁膜およびメタル配線層をそれぞれ３層ずつとしたが、２層ずつとしてもよく、それにより、固体撮像素子の薄型化がさらに可能となる。また、層間絶縁膜およびメタル配線層をそれぞれ４層以上として、集光のための受光画素とマイクロレンズとの距離を広げても構わない。 In the above-described embodiment, three interlayer insulating films and three metal wiring layers are provided, but two layers may be provided, thereby further reducing the thickness of the solid-state imaging device. Further, the interlayer insulating film and the metal wiring layer may each be four or more layers, and the distance between the light receiving pixel for condensing and the microlens may be increased.

さらに、各メタル配線層をダマシン工法によるＣｕ膜としたが、エッチング法によるＡｌ膜で形成してもよい。これにより、入射光制限膜がＡｌで形成されるため、Ｃｕよりも遮光性を高くすることが可能となる。 Furthermore, although each metal wiring layer is a Cu film by a damascene method, it may be formed by an Al film by an etching method. Thereby, since the incident light limiting film is formed of Al, it is possible to make the light shielding property higher than that of Cu.

本発明は、受光画素領域の各画素への入射光量の均一性を高めながら集光率も向上でき、かつ黒基準信号を生成するオプティカルブラックを構成する遮光画素領域への不正入射光を防止することができ、光電変換素子を用いて撮像する固体撮像装置及びその製造方法等に有用である。 The present invention can improve the light collection rate while improving the uniformity of the amount of light incident on each pixel in the light-receiving pixel region, and prevents illegal incident light on the light-shielding pixel region constituting the optical black that generates the black reference signal. It is useful for a solid-state imaging device that captures an image using a photoelectric conversion element, a manufacturing method thereof, and the like.

本発明の固体撮像装置の構成を示す断面図Sectional drawing which shows the structure of the solid-state imaging device of this invention 本発明の固体撮像装置の構成を示す平面図The top view which shows the structure of the solid-state imaging device of this invention 本発明の固体撮像装置の製造方法における素子領域形成工程を説明する工程断面図Process sectional drawing explaining the element area | region formation process in the manufacturing method of the solid-state imaging device of this invention 本発明の固体撮像装置の製造方法における遮光膜形成工程を説明する工程断面図Process sectional drawing explaining the light shielding film formation process in the manufacturing method of the solid-state imaging device of this invention 本発明の固体撮像装置の製造方法における層内レンズ形成工程を説明する工程断面図Process sectional drawing explaining the intra-layer lens formation process in the manufacturing method of the solid-state imaging device of this invention 本発明の固体撮像装置の製造方法におけるカラーフィルタ層形成工程を説明する工程断面図Process sectional drawing explaining the color filter layer formation process in the manufacturing method of the solid-state imaging device of this invention マイクロレンズと凸型層内レンズを有する固体撮像装置の構成を示す断面図Sectional drawing which shows the structure of the solid-state imaging device which has a micro lens and a convex inner lens

符号の説明Explanation of symbols

１遮光画素領域
２境界画素領域
３受光画素領域
４光電変換素子
１１第一層間絶縁膜
１２第二層間絶縁膜
１３第三層間絶縁膜
１４第四層間絶縁膜
２１第一メタル配線層
２２第二メタル配線層
２３第三メタル配線層
２４入射光制限膜
２５遮光膜
３１保護膜
３２層内レンズ
３３第一平坦化膜
３４カラーフィルタ膜
３５第二平坦化膜
３６マイクロレンズ
１０４第一メタル配線層
１０５第二メタル配線層
１０６第三メタル配線層
１０７保護膜
１０８層内レンズ
１０９平坦化膜
１１０カラーフィルタ層
１１１マイクロレンズ DESCRIPTION OF SYMBOLS 1 Light-shielding pixel area | region 2 Boundary pixel area | region 3 Light reception pixel area | region 4 Photoelectric conversion element 11 1st interlayer insulation film 12 2nd interlayer insulation film 13 3rd interlayer insulation film 14 4th interlayer insulation film 21 1st metal wiring layer 22 2nd Metal wiring layer 23 Third metal wiring layer 24 Incident light limiting film 25 Light-shielding film 31 Protective film 32 Inner lens 33 First planarizing film 34 Color filter film 35 Second planarizing film 36 Microlens 104 First metal wiring layer 105 Second metal wiring layer 106 Third metal wiring layer 107 Protective film 108 In-layer lens 109 Flattening film 110 Color filter layer 111 Microlens

Claims

主面に光電変換素子が形成され、受光画素領域と境界画素領域と遮光画素領域とを備えた半導体基板と、
前記半導体基板上に形成された層間絶縁膜と、
前記層間絶縁膜上に形成された配線層と、
前記受光画素領域における前記層間絶縁膜上に形成された第１の層内レンズと、
前記境界画素領域における前記層間絶縁膜上に形成された第１の入射光制限膜と、
前記遮光画素領域における前記層間絶縁膜上に形成された遮光膜とを備え、
前記境界画素領域は、受光画素領域と前記遮光画素領域の間に形成されていることを特徴とする固体撮像装置。 A semiconductor substrate having a photoelectric conversion element formed on a main surface and having a light receiving pixel region, a boundary pixel region, and a light shielding pixel region;
An interlayer insulating film formed on the semiconductor substrate;
A wiring layer formed on the interlayer insulating film;
A first inner lens formed on the interlayer insulating film in the light receiving pixel region;
A first incident light limiting film formed on the interlayer insulating film in the boundary pixel region;
A light shielding film formed on the interlayer insulating film in the light shielding pixel region,
The boundary pixel region is formed between a light-receiving pixel region and the light-shielding pixel region.

前記境界画素領域における前記層間絶縁膜上にさらに第２の層内レンズを備えることを特徴とする請求項１記載の固体撮像装置。 The solid-state imaging device according to claim 1, further comprising a second intra-layer lens on the interlayer insulating film in the boundary pixel region.

前記遮光画素領域における前記層間絶縁膜上にさらに第２の入射光制限膜を備えることを特徴とする請求項１または請求項２のいずれかに記載の固体撮像装置。 The solid-state imaging device according to claim 1, further comprising a second incident light limiting film on the interlayer insulating film in the light-shielding pixel region.

前記配線層と前記第１の入射光制限膜及び第２の入射光制限膜は同一の材料であることを特徴とする請求項１〜請求項３のいずれかに記載の固体撮像装置。 The solid-state imaging device according to claim 1, wherein the wiring layer, the first incident light limiting film, and the second incident light limiting film are made of the same material.

前記受光画素領域における前記層間絶縁膜上にカラーフィルタを備えることを特徴とする請求項１〜請求項４のいずれかに記載の固体撮像装置。 The solid-state imaging device according to claim 1, further comprising a color filter on the interlayer insulating film in the light receiving pixel region.

前記受光画素領域における前記層間絶縁膜上にマイクロレンズを備えることを特徴とする請求項１〜請求項５のいずれかに記載の固体撮像装置。 The solid-state imaging device according to claim 1, further comprising a microlens on the interlayer insulating film in the light receiving pixel region.

外部と接続するためのコンタクトパッドをさらに備え、前記遮光膜と前記コンタクトパッドは同一の材料で形成されていることを特徴とする請求項１〜請求項６のいずれかに記載の固体撮像装置。 The solid-state imaging device according to claim 1, further comprising a contact pad for connecting to the outside, wherein the light shielding film and the contact pad are formed of the same material.

前記第１の層内レンズの底面は前記遮光膜の上面よりも低いことを特徴とする請求項１〜請求項７のいずれかに記載の固体撮像装置。 8. The solid-state imaging device according to claim 1, wherein a bottom surface of the first in-layer lens is lower than an upper surface of the light shielding film.

受光画素領域と境界画素領域と遮光画素領域とを備えた半導体基板に光電変換素子を形成する工程と、
前記半導体基板上に層間絶縁膜を形成する工程と、
前記層間絶縁膜上に配線層を形成する工程と、
前記境界画素領域における前記層間絶縁膜上に入射光制限膜を形成する工程と、
前記遮光画素領域における前記層間絶縁膜上に遮光膜を形成する工程と、
前記受光画素領域における前記層間絶縁膜上に層内レンズを形成する工程とからなることを特徴とする固体撮像装置の製造方法。 Forming a photoelectric conversion element on a semiconductor substrate having a light receiving pixel region, a boundary pixel region, and a light shielding pixel region;
Forming an interlayer insulating film on the semiconductor substrate;
Forming a wiring layer on the interlayer insulating film;
Forming an incident light limiting film on the interlayer insulating film in the boundary pixel region;
Forming a light shielding film on the interlayer insulating film in the light shielding pixel region;
And a step of forming an intra-layer lens on the interlayer insulating film in the light-receiving pixel region.

前記配線層の形成工程と前記入射光制限膜の形成工程とを同時に行うことを特徴とする請求項９に記載の固体撮像装置の製造方法。 The method for manufacturing a solid-state imaging device according to claim 9, wherein the wiring layer forming step and the incident light limiting film forming step are performed simultaneously.