JP3747682B2 - Solid-state imaging device and manufacturing method thereof - Google Patents

Solid-state imaging device and manufacturing method thereof Download PDF

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JP3747682B2
JP3747682B2 JP07235699A JP7235699A JP3747682B2 JP 3747682 B2 JP3747682 B2 JP 3747682B2 JP 07235699 A JP07235699 A JP 07235699A JP 7235699 A JP7235699 A JP 7235699A JP 3747682 B2 JP3747682 B2 JP 3747682B2
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microlens
light receiving
solid
imaging device
state imaging
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JP2000269474A (en
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宏紀 大森
達彦 古田
貴雄 田口
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Toppan Inc
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14683—Processes or apparatus peculiar to the manufacture or treatment of these devices or parts thereof
    • H01L27/14685—Process for coatings or optical elements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14601—Structural or functional details thereof
    • H01L27/1462—Coatings
    • H01L27/14621—Colour filter arrangements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14601—Structural or functional details thereof
    • H01L27/14625—Optical elements or arrangements associated with the device
    • H01L27/14627—Microlenses

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  • Engineering & Computer Science (AREA)
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  • General Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Transforming Light Signals Into Electric Signals (AREA)
  • Solid State Image Pick-Up Elements (AREA)

Description

【０００１】
【発明の属する技術分野】
本発明はマイクロレンズ付きの固体撮像素子及びその製造方法に関する。
【０００２】
【従来の技術】
従来、固体撮像素子では、電荷転送部など光電変換に寄与しない領域が各画素に存在しているため、画素面全体に占める受光部の受光面に対する開口率が15〜30％程度であり入射光の利用率が十分でないと言う問題がある。このような問題を解消し感度向上を達成するために、半導体プロセスによる受光部以外の領域の微細化する技術や、高エネルギーイオン注入技術を導入して転送レジスタ部の飽和電荷量を高めることにより転送レジスタ部の面積を小さくし受光部面積及び開口面積を大きくする試みがなされているが、これらは固体撮像素子の構造的に限界がある。そこで近年では図２に示すように受光部上部に凸状のマイクロレンズを設け、入射した光を受光部に効率的に集光させ実効開口率を高めたオンチップマイクロレンズを有した撮像素子が提供されている。
【０００３】
さらにカラー固体撮像素子においては、マイクロレンズに加えてカラーフィルタが備えられている。基板表層部に光電変換を行う受光部が複数箇所形成されている撮像素子に、カラーフィルタ及びマイクロレンズを形成する一般的な製造方法は下記の通りである。
▲１▼受光部の透明樹脂による受光部の穴埋め
▲２▼受光部の平坦化
▲３▼カラーフィルタの形成
▲４▼透明樹脂によるカラーフィルタの平坦化
▲５▼マイクロレンズの形成
【０００４】
特に▲５▼マイクロレンズの形成を図面を参照して説明する。図２は従来のマイクロレンズの製造方法である。１は半導体基板、２は受光部、３は電荷転送部、４は下部平坦化層、５はカラーフィルタ、６は遮光膜、７は上部平坦化層である（図２（ａ）参照）。上部平坦化層上にマイクロレンズ形成用レジストを塗布し、従来のフォトリソグラフィー技術によりパターン１２を形成した後（図２（ｂ）参照）、加熱処理を施し、パターンを変形させて受光部上に凸状のマイクロレンズ１３を形成する（図２（ｃ）参照）。
【０００５】
【発明が解決しようとする課題】
近年、固体撮像素子の高解像度化や小型化に伴い、マイクロレンズを高精細化する必要がある。併せて受光素子の受光面積が小さくなる為、マイクロレンズの集光位置を保ちながらレンズの幅を広げレンズ間の距離をできるだけ小さくすることが望ましい。すなわち図２（ｃ）のマイクロレンズ間スペースをできるだけ小さくすることが望ましい。
【０００６】
しかしながら、このような従来の各受光部に対向する位置に入射光を集光させるマイクロレンズを設けた固体撮像素子では、光電変換有効領域の入射光を効率よく集光するために、マイクロレンズの幅を単位画素ピッチにできるだけ近づけようとすると、加熱時にレンズの膨張（距離の広がり）し、収縮するため、隣接するレンズ１４が融着してくずれ、実効開口率が小さくなり、高い実効感度が得られないという問題点があった（図３参照）。
【０００７】
他方、カラーフィルタに用いられる、Ｒ、Ｇ、Ｂ（原色フィルタ）、または、Ｃ、Ｍ、Ｙ（補色フィルタ）の各色の透過率にはばらつきがあり、それが原因となり良好な色再現性が得られないという問題点があった。
【０００８】
本発明は、マイクロレンズ形成時のレンズ間スペースの制御性に優れ、またレンズ融着によるレンズ未形成部分の発生を抑え、マイクロレンズ形成安定性を高めることにより実効感度の高く、かつ、良好な色再現性が得られる固体撮像素子及びその製造方法の提供を目的とする。
【０００９】
【課題を解決するための手段】
請求項１に記載の発明は、半導体基板上に複数の受光部と、受光部上にベイヤー配列のカラーフィルタとを備え、その上に少なくともマイクロレンズを形成する固体撮像素子の製造方法であって、複数の受光部の中から市松状に選択された受光部上にマイクロレンズを形成する第一工程、前記第一工程において選択されなかった受光部上に第一工程で形成したマイクロレンズとは特性の異なるマイクロレンズを形成する第二工程を少なくとも具備することを特徴とする固体撮像素子の製造方法である。
【００１０】
請求項２に記載の発明は、半導体基板上に複数の受光部と、受光部上にベイヤー配列のカラーフィルタとを備え、その上に少なくともマイクロレンズを形成する固体撮像素子であって、複数の受光部の中から市松状に選択された受光部上のマイクロレンズを形成するレジストと、他のマイクロレンズを形成するレジストの特性が異なることを特徴とする固体撮像素子である。
【００１１】
【発明の実施の形態】
従来技術のように全てのマイクロレンズを同時に作成した場合、各マイクロレンズはそれぞれ膨張するため、隣接するレンズの融着が起こり易いが、請求項１に係わる固体撮像素子の製造方法によれば、第一工程により作成されたマイクロレンズは溶融・硬化等により素性が変化し、第二工程においてはほとんど膨張しないため、例え、第一工程と第二工程の加熱条件が同じであってもレンズの融着が起こり難い。
【００１２】
また、請求項２に係る固体撮像素子によれば、例えば、複数の受光部の中から市松状に選択された受光部上のマイクロレンズを形成するレジストの軟化点と、他のマイクロレンズを形成するレジストの軟化点を異なることすれば、他のマイクロレンズを形成する工程（第二工程）の加熱条件が複数の受光部の中から市松状に選択された受光部上のマイクロレンズを形成する工程（第一工程）より高いものとなってもレンズの融着が起こり難い。また、カラーフィルタの色配列が特定の色が市松状に並ぶベイヤー配列、インターライン配列、フィールド色差順次配列、フレームインターリーブ配列を採用し、第一工程で用いるレジストと第二工程で用いるレジストの屈折率（すなわち、集光効率）を異ならせれば、各色の感度のばらつきを調整することもできる。
【００１３】
［実施例１］
次に本発明について図面を参照にして説明する。図１は本発明の実施例である固体撮像素子の製造工程を示した断面構造及び平面構造の模式図である。本実施例では単位画素ピッチが５．０μｍの固体撮像素子を用いた。図１（ａ）は、固体撮像素子にカラーフィルタを形成した時の固体撮像素子の断面図である。１は半導体基板、２は受光素子、３は電荷転送部、４は下部平坦化層、５はカラーフィルタ、６は遮光膜、７は上部平坦化層であり従来の構成と同じであるため、同一の符号を付けて説明を省略する。
【００１４】
次に、第一工程として、マイクロレンズ用レジストを用い、公知のフォトリソグラフィー法によりマイクロレンズとなるパターン８を形成する（図１（ｂ）参照）。この際、パターンは複数の受光部の中から市松状に選択された受光部のカラーフィルタ上に形成する。本実施例の場合、カラーフィルタの色配列がベイヤー配列を採用するため、Ｒ（赤）、Ｂ（青）の領域が市松状に並ぶので、そのカラーフィルタ上に形成する。次に、１６０℃の加熱処理にてマイクロレンズ１０を形成する（図１（ｃ）参照）。この時のマイクロレンズ用レジストのパターン寸法は４．５μｍ（パターン間スペースは１．０μｍ）で、加熱処理後のレンズ径は４．９μｍである。その後、第二工程として、第一工程において選択されなかった受光部のカラーフィルタ上に前記と同様にパターン９を形成する（図１（ｄ）参照）。本実施例の場合、Ｇ（緑) のカラーフィルタ上に形成することとなる。この時のマイクロレンズ用レジストのパターン寸法は４．５μｍで、加熱処理後のレンズ径は４．９μｍである。これによりレンズ間スペースが０．２μｍのマイクロレンズが高い生産安定性で形成でき、従来法に比べ実効感度が約１０％向上した。
【００１５】
［実施例２］
実施例１と同一の固体撮像素子上に、第一工程として、軟化点が１４０℃のマイクロレンズ用レジストを用い、公知のフォトリソグラフィー法によりマイクロレンズとなるパターン８を形成する。この際、パターンは複数の受光部の中から市松状に選択された受光部のカラーフィルタ上に形成する。本実施例の場合、Ｒ（赤）、Ｂ（青）の領域が市松状に並ぶので、そのカラーフィルタ上に形成する。次に、１５０℃の加熱処理にてマイクロレンズ１０を形成する。この時のマイクロレンズ用レジストのパターン寸法は４．５μｍで、加熱処理後のレンズ径は４．９μｍである。その後、第二工程として、第一工程において選択されなかった受光部のカラーフィルタ上に軟化点が１５０℃のマイクロレンズ用レジストを用い、１６０℃の加熱処理にてパターン９を形成する。本実施例の場合、Ｇ（緑) のカラーフィルタ上に形成することとなる。この時のマイクロレンズ用レジストのパターン寸法は４．５μｍで、加熱処理後のレンズ径は４．９μｍである。これによりレンズ間スペースが０．２μｍのマイクロレンズが高い生産安定性で形成でき、従来法に比べ実効感度が約１０％向上した。
【００１６】
［実施例３］
実施例１と同一の固体撮像素子上に、第一工程として、屈折率が１．５５のマイクロレンズ用レジストを用い、公知のフォトリソグラフィー法によりマイクロレンズとなるパターン８を形成する。この際、パターンは複数の受光部の中から市松状に選択された受光部のカラーフィルタ上に形成する。本実施例の場合、Ｒ（赤）、Ｂ（青）の領域が市松状に並ぶので、そのカラーフィルタ上に形成する。次に、１６０℃の加熱処理にてマイクロレンズ１０を形成する。この時のマイクロレンズ用レジストのパターン寸法は４．５μｍで、加熱処理後のレンズ径は４．９μｍである。その後、第二工程として、第一工程において選択されなかった受光部のカラーフィルタ上に屈折率が１．５７のマイクロレンズ用レジストを用い、１６０℃の加熱処理にてパターン９を形成する。本実施例の場合、Ｇ（緑) のカラーフィルタ上に形成することとなる。この時のマイクロレンズ用レジストのパターン寸法は４．５μｍで、加熱処理後のレンズ径は４．９μｍである。これによりレンズ間スペースが０．２μｍのマイクロレンズが高い生産安定性で形成でき、従来法に比べ色再現性が約１０％向上した。
【００１７】
［比較例］
実施例１と同一の固体撮像素子上に実施例１と同一のマイクロレンズ用レジストを塗布し、公知のフォトリソグラフィー法により全てのパターンを形成する。この時のパターンニング寸法は４．５μｍ（パターン間スペースは１．０μｍ）である。その後加熱処理により、マイクロレンズを形成したところ、図３のようにレンズの融着が多く、生産安定性が低かった。
【００１８】
【発明の効果】
以上より明らかなように、請求項１に係る固体撮像素子の製造方法によれば、第一工程により作成されたマイクロレンズは溶融・硬化等により素性が変化し、第二工程においてはほとんど膨張しないため、例え、第一工程と第二工程の加熱条件が同じであってもレンズの融着が起こり難い。
【００１９】
よって、隣接したマイクロレンズ同士が接触し、マイクロレンズ未形成部分の発生を防ぐことができるので、入射光を単位画素ピッチ近傍の幅で有効的に集光し、実効感度を向上させることができる。
【００２０】
請求項２に係る固体撮像素子によれば、例えば、複数の受光部の中から市松状に選択された受光部上のマイクロレンズを形成するレジストの軟化点と、他のマイクロレンズを形成するレジストの軟化点を異ならせた場合は、他のマイクロレンズを形成する工程（第二工程）の加熱条件が複数の受光部の中から市松状に選択された受光部上のマイクロレンズを形成する工程（第一工程）より高いものとなって、更に、レンズの融着が起こり難い。
【００２１】
また、カラーフィルタの色配列が特定の色が市松状に並ぶベイヤー配列、インターライン配列、フィールド色差順次配列、フレームインターリーブ配列を採用し、第一工程で用いるレジストと第二工程で用いるレジストの屈折率（すなわち、集光効率）を異ならせた場合は、各色の感度のばらつきを調整することもできる。
【００２２】
【図面の簡単な説明】
【図１】本発明の実施例の固体撮像素子の製造工程を示した断面構造の説明図である。
【図２】従来の固体撮像素子の製造工程を示した断面構造の説明図である。
【図３】融着したマイクロレンズの説明図である。
【符号の説明】
１ 半導体基板
２ 受光部
３ 電荷転送部
４ 下部平坦化層
５ カラーフィルタ
６ 遮光層
７ 上部平坦化層
８ 第一工程で形成されたパターン
９ 第二工程で形成されたパターン
１０ 第一工程で形成されたマイクロレンズ
１１ 第二工程で形成されたマイクロレンズ
１２ パターン
１３ マイクロレンズ
１４ 融着したマイクロレンズ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a solid-state imaging device with a microlens and a method for manufacturing the same.
[0002]
[Prior art]
Conventionally, in a solid-state imaging device, an area that does not contribute to photoelectric conversion, such as a charge transfer unit, exists in each pixel. Therefore, the aperture ratio with respect to the light receiving surface of the light receiving unit in the entire pixel surface is about 15 to 30%, and incident light There is a problem that the utilization rate is not enough. In order to eliminate such problems and achieve sensitivity improvement, by introducing a technology to reduce the area other than the light receiving part by a semiconductor process and a high energy ion implantation technique to increase the saturation charge amount of the transfer register part Attempts have been made to reduce the area of the transfer register section and increase the area of the light receiving section and the aperture area, but these have limitations in the structure of the solid-state imaging device. Therefore, in recent years, as shown in FIG. 2, there is provided an imaging device having an on-chip microlens in which a convex microlens is provided on the light receiving portion and incident light is efficiently condensed on the light receiving portion to increase the effective aperture ratio. Is provided.
[0003]
Further, the color solid-state imaging device includes a color filter in addition to the microlens. A general manufacturing method for forming a color filter and a microlens on an imaging device in which a plurality of light receiving portions that perform photoelectric conversion on the substrate surface layer portion is formed is as follows.
(1) Filling of the light receiving portion with the transparent resin of the light receiving portion (2) Flattening of the light receiving portion (3) Formation of the color filter (4) Flattening of the color filter with the transparent resin (5) Formation of the micro lens
In particular, (5) formation of microlenses will be described with reference to the drawings. FIG. 2 shows a conventional method for manufacturing a microlens. 1 is a semiconductor substrate, 2 is a light receiving portion, 3 is a charge transfer portion, 4 is a lower planarizing layer, 5 is a color filter, 6 is a light shielding film, and 7 is an upper planarizing layer (see FIG. 2A). After applying a microlens forming resist on the upper planarizing layer and forming a pattern 12 by a conventional photolithography technique (see FIG. 2B), heat treatment is performed to deform the pattern on the light receiving portion. Convex microlenses 13 are formed (see FIG. 2C).
[0005]
[Problems to be solved by the invention]
In recent years, it has been necessary to increase the definition of microlenses with higher resolution and smaller size of solid-state imaging devices. In addition, since the light receiving area of the light receiving element is reduced, it is desirable to increase the width of the lens while keeping the condensing position of the microlens to reduce the distance between the lenses as much as possible. That is, it is desirable to make the space between the microlenses shown in FIG.
[0006]
However, in such a solid-state imaging device provided with a microlens that condenses incident light at a position facing each conventional light receiving unit, in order to efficiently collect incident light in a photoelectric conversion effective region, If the width is made as close as possible to the unit pixel pitch, the lens expands (expands the distance) and contracts during heating, so that the adjacent lens 14 is fused and displaced, the effective aperture ratio is reduced, and high effective sensitivity is achieved. There was a problem that it could not be obtained (see FIG. 3).
[0007]
On the other hand, the transmittance of each color of R, G, B (primary color filter) or C, M, Y (complementary color filter) used in the color filter varies, and this causes good color reproducibility. There was a problem that it could not be obtained.
[0008]
The present invention is excellent in controllability of the inter-lens space at the time of microlens formation, suppresses the occurrence of a lens non-formed part due to lens fusion, and improves the microlens formation stability, resulting in high effective sensitivity and good An object of the present invention is to provide a solid-state imaging device capable of obtaining color reproducibility and a manufacturing method thereof.
[0009]
[Means for Solving the Problems]
The invention according to claim 1 is a method for manufacturing a solid-state imaging device, comprising a plurality of light receiving portions on a semiconductor substrate, and a Bayer array color filter on the light receiving portion, and forming at least a microlens thereon. The first step of forming a microlens on a light receiving part selected in a checkered pattern from among a plurality of light receiving parts, the micro lens formed in the first step on the light receiving part not selected in the first step At least a second step of forming microlenses having different characteristics is provided.
[0010]
The invention according to claim 2 is a solid-state imaging device comprising a plurality of light receiving portions on a semiconductor substrate, and a Bayer array color filter on the light receiving portion, and at least forming a microlens thereon . The solid-state imaging device is characterized in that a resist for forming a microlens on a light receiving portion selected in a checkered pattern from among the light receiving portions is different from a resist for forming another microlens.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
When all the microlenses are created at the same time as in the prior art, each microlens expands, so that adjacent lenses are likely to be fused. According to the method for manufacturing a solid-state imaging device according to claim 1, The microlens created in the first step changes its characteristics due to melting / curing, etc., and hardly expands in the second step, so even if the heating conditions in the first step and the second step are the same, Fusing is unlikely to occur.
[0012]
In addition, according to the solid-state imaging device according to claim 2, for example, a softening point of a resist that forms a microlens on a light receiving portion selected in a checkered pattern from among a plurality of light receiving portions and another microlens are formed. If the softening point of the resist to be changed is different, the microlenses on the light-receiving unit are formed in which the heating conditions in the step of forming another microlens (second step) are selected from a plurality of light-receiving units in a checkered pattern. Even if it is higher than the step (first step), the lens is hardly fused. In addition, a Bayer array, interline array, field color difference sequential array, and frame interleave array in which specific colors are arranged in a checkered pattern are used for the color filter, and the refraction of the resist used in the first step and the resist used in the second step If the rate (that is, the light collection efficiency) is varied, the variation in sensitivity of each color can be adjusted.
[0013]
[Example 1]
Next, the present invention will be described with reference to the drawings. FIG. 1 is a schematic view of a cross-sectional structure and a planar structure showing a manufacturing process of a solid-state imaging device which is an embodiment of the present invention. In this embodiment, a solid-state imaging device having a unit pixel pitch of 5.0 μm was used. FIG. 1A is a cross-sectional view of a solid-state image sensor when a color filter is formed on the solid-state image sensor. 1 is a semiconductor substrate, 2 is a light receiving element, 3 is a charge transfer unit, 4 is a lower planarizing layer, 5 is a color filter, 6 is a light shielding film, and 7 is an upper planarizing layer, which is the same as the conventional configuration. The same reference numerals are given and the description is omitted.
[0014]
Next, as a first step, a microlens resist is used to form a pattern 8 to be a microlens by a known photolithography method (see FIG. 1B). At this time, the pattern is formed on the color filter of the light receiving portion selected in a checkered pattern from among the plurality of light receiving portions. In the case of the present embodiment, since the color arrangement of the color filter adopts the Bayer arrangement, the R (red) and B (blue) regions are arranged in a checkered pattern, and are formed on the color filter. Next, the microlens 10 is formed by a heat treatment at 160 ° C. (see FIG. 1C). The pattern size of the microlens resist at this time is 4.5 μm (the space between patterns is 1.0 μm), and the lens diameter after the heat treatment is 4.9 μm. Thereafter, as a second step, a pattern 9 is formed on the color filter of the light receiving section that was not selected in the first step (see FIG. 1D). In the present embodiment, it is formed on a G (green) color filter. The pattern size of the microlens resist at this time is 4.5 μm, and the lens diameter after the heat treatment is 4.9 μm. As a result, a microlens having a lens-to-lens space of 0.2 μm can be formed with high production stability, and the effective sensitivity is improved by about 10% compared to the conventional method.
[0015]
[Example 2]
On the same solid-state imaging device as in Example 1, as a first step, a microlens resist having a softening point of 140 ° C. is used, and a pattern 8 to be a microlens is formed by a known photolithography method. At this time, the pattern is formed on the color filter of the light receiving portion selected in a checkered pattern from among the plurality of light receiving portions. In the present embodiment, the R (red) and B (blue) regions are arranged in a checkered pattern, and are formed on the color filter. Next, the microlens 10 is formed by heat treatment at 150 ° C. The pattern size of the microlens resist at this time is 4.5 μm, and the lens diameter after the heat treatment is 4.9 μm. Thereafter, as a second step, a pattern 9 is formed by heat treatment at 160 ° C. using a microlens resist having a softening point of 150 ° C. on the color filter of the light receiving portion not selected in the first step. In the present embodiment, it is formed on a G (green) color filter. The pattern size of the microlens resist at this time is 4.5 μm, and the lens diameter after the heat treatment is 4.9 μm. As a result, a microlens having a lens-to-lens space of 0.2 μm can be formed with high production stability, and the effective sensitivity is improved by about 10% compared to the conventional method.
[0016]
[Example 3]
On the same solid-state imaging device as in Example 1, as a first step, a microlens resist having a refractive index of 1.55 is used to form a pattern 8 that becomes a microlens by a known photolithography method. At this time, the pattern is formed on the color filter of the light receiving portion selected in a checkered pattern from among the plurality of light receiving portions. In the present embodiment, the R (red) and B (blue) regions are arranged in a checkered pattern, and are formed on the color filter. Next, the microlens 10 is formed by heat treatment at 160 ° C. The pattern size of the microlens resist at this time is 4.5 μm, and the lens diameter after the heat treatment is 4.9 μm. Thereafter, as a second step, a pattern 9 is formed by a heat treatment at 160 ° C. using a microlens resist having a refractive index of 1.57 on the color filter of the light receiving portion not selected in the first step. In the present embodiment, it is formed on a G (green) color filter. The pattern size of the microlens resist at this time is 4.5 μm, and the lens diameter after the heat treatment is 4.9 μm. As a result, a microlens having a lens-to-lens space of 0.2 μm can be formed with high production stability, and the color reproducibility is improved by about 10% compared to the conventional method.
[0017]
[Comparative example]
The same microlens resist as in Example 1 is applied on the same solid-state imaging device as in Example 1, and all patterns are formed by a known photolithography method. The patterning dimension at this time is 4.5 μm (the space between patterns is 1.0 μm). Thereafter, a microlens was formed by heat treatment. As a result, as shown in FIG. 3, the lens was frequently fused and the production stability was low.
[0018]
【The invention's effect】
As is clear from the above, according to the method for manufacturing a solid-state imaging device according to claim 1, the microlens created in the first step changes in characteristics due to melting and curing, and hardly expands in the second step. Therefore, even if the heating conditions in the first step and the second step are the same, lens fusion is unlikely to occur.
[0019]
Accordingly, adjacent microlenses can be brought into contact with each other to prevent generation of a microlens non-formed portion, so that incident light can be effectively condensed with a width near the unit pixel pitch, and effective sensitivity can be improved. .
[0020]
According to the solid-state imaging device according to claim 2, for example, a softening point of a resist that forms a microlens on a light receiving portion selected in a checkered pattern from among a plurality of light receiving portions, and a resist that forms another microlens When the softening points of the microlenses are made different, the step of forming the microlenses on the light-receiving portion in which the heating conditions in the step of forming another microlens (second step) are selected from a plurality of light-receiving portions in a checkered pattern (1st process) It becomes a higher thing, and also the fusion | melting of a lens does not occur easily.
[0021]
In addition, a Bayer array, interline array, field color difference sequential array, and frame interleave array in which specific colors are arranged in a checkered pattern are used for the color filter, and the refraction of the resist used in the first step and the resist used in the second step When the rate (that is, the light collection efficiency) is varied, the variation in sensitivity of each color can be adjusted.
[0022]
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a cross-sectional structure illustrating a manufacturing process of a solid-state imaging device according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram of a cross-sectional structure showing a manufacturing process of a conventional solid-state imaging device.
FIG. 3 is an explanatory diagram of a fused microlens.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2 Light-receiving part 3 Charge transfer part 4 Lower planarization layer 5 Color filter 6 Light-shielding layer 7 Upper planarization layer 8 Pattern 9 formed in the first process Pattern 10 formed in the second process Formed in the first process Microlens 11 Microlens 12 Formed in Second Step 12 Pattern 13 Microlens 14 Fused Microlens

Claims (2)

半導体基板上に複数の受光部と、受光部上にベイヤー配列のカラーフィルタとを備え、その上に少なくともマイクロレンズを形成する固体撮像素子の製造方法であって、複数の受光部の中から市松状に選択された受光部上にマイクロレンズを形成する第一工程、前記第一工程において選択されなかった受光部上に第一工程で形成したマイクロレンズとは特性の異なるマイクロレンズを形成する第二工程を少なくとも具備することを特徴とする固体撮像素子の製造方法。A method for manufacturing a solid-state imaging device, comprising: a plurality of light receiving portions on a semiconductor substrate; and a Bayer array color filter on the light receiving portion, and forming at least a microlens thereon. A first step of forming a microlens on the light receiving portion selected in a shape, and a first step of forming a microlens having characteristics different from those of the microlens formed in the first step on the light receiving portion not selected in the first step . A method for manufacturing a solid-state imaging device, comprising at least two steps. 半導体基板上に複数の受光部と、受光部上にベイヤー配列のカラーフィルタとを備え、その上に少なくともマイクロレンズを形成する固体撮像素子であって、複数の受光部の中から市松状に選択された受光部上のマイクロレンズを形成するレジストと、他のマイクロレンズを形成するレジストの特性が異なることを特徴とする固体撮像素子。 A plurality of light receiving portions on a semiconductor substrate, and a color filter of the Bayer array on the light receiving unit, a solid-state imaging device to form at least a microlens thereon, selected from a plurality of light receiving portions in a checkered pattern a solid-state imaging device, characterized and the resist for forming a microlens on the light-receiving portion that is, that the properties of the resist for forming the other micro lenses are different.
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