JPH04226073A - Solid-state image sensor and its manufacture - Google Patents
Solid-state image sensor and its manufactureInfo
- Publication number
- JPH04226073A JPH04226073A JP3107260A JP10726091A JPH04226073A JP H04226073 A JPH04226073 A JP H04226073A JP 3107260 A JP3107260 A JP 3107260A JP 10726091 A JP10726091 A JP 10726091A JP H04226073 A JPH04226073 A JP H04226073A
- Authority
- JP
- Japan
- Prior art keywords
- microlens
- lens
- film
- solid
- state imaging
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 6
- 239000010408 film Substances 0.000 claims abstract description 45
- 239000013039 cover film Substances 0.000 claims abstract description 24
- 238000003384 imaging method Methods 0.000 claims description 28
- 238000000034 method Methods 0.000 claims description 19
- 230000004075 alteration Effects 0.000 claims description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 abstract description 18
- 229910052681 coesite Inorganic materials 0.000 abstract description 9
- 229910052906 cristobalite Inorganic materials 0.000 abstract description 9
- 239000000377 silicon dioxide Substances 0.000 abstract description 9
- 235000012239 silicon dioxide Nutrition 0.000 abstract description 9
- 229910052682 stishovite Inorganic materials 0.000 abstract description 9
- 229910052905 tridymite Inorganic materials 0.000 abstract description 9
- 230000035945 sensitivity Effects 0.000 abstract description 7
- 239000000463 material Substances 0.000 description 11
- 238000010586 diagram Methods 0.000 description 10
- 229920002120 photoresistant polymer Polymers 0.000 description 7
- 238000007796 conventional method Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- 229910010272 inorganic material Inorganic materials 0.000 description 5
- 239000011147 inorganic material Substances 0.000 description 5
- 238000000151 deposition Methods 0.000 description 3
- 230000008021 deposition Effects 0.000 description 3
- 230000003287 optical effect Effects 0.000 description 3
- 239000011368 organic material Substances 0.000 description 3
- 239000000758 substrate Substances 0.000 description 3
- 206010034972 Photosensitivity reaction Diseases 0.000 description 2
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 description 2
- 238000005229 chemical vapour deposition Methods 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 230000036211 photosensitivity Effects 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 229910052814 silicon oxide Inorganic materials 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000001947 vapour-phase growth Methods 0.000 description 2
- 229910003638 H2SiF6 Inorganic materials 0.000 description 1
- 229910052581 Si3N4 Inorganic materials 0.000 description 1
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000004327 boric acid Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 238000001020 plasma etching Methods 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- ZEFWRWWINDLIIV-UHFFFAOYSA-N tetrafluorosilane;dihydrofluoride Chemical compound F.F.F[Si](F)(F)F ZEFWRWWINDLIIV-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Color Television Image Signal Generators (AREA)
- Solid State Image Pick-Up Elements (AREA)
- Transforming Light Signals Into Electric Signals (AREA)
Abstract
Description
【０００１】0001
【産業上の利用分野】本発明は固体撮像装置の構造およ
びその製造方法に関し、特に光感度を著しく改善するこ
とを特徴とした固体撮像装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of a solid-state imaging device and its manufacturing method, and more particularly to a solid-state imaging device characterized by significantly improved photosensitivity.
【０００２】0002
【従来の技術】固体撮像装置としては、すでに種々の構
造が提案され一部は実用化されている。従来の固体撮像
装置は、例えば図４に示す如き構造である。同図は電荷
転送（ＣＣＤ）型の２次元固体撮像装置の平面構造を説
明する図であり、図に於て１１ａ〜１１ｄ，１２ａ〜１
２ｄは光電変換を行うフォトダイオードを、２１，２２
はＣＣＤチャネルを示す。当該固体撮像装置の動作は概
略次の通りである。まず、固体撮像装置上に投影される
光パターン強度に応じた電荷がフォトダイオード１１ａ
〜１１ｄ，１２ａ〜１２ｄに蓄積される。所定時間経過
後にフォトダイオードに蓄積された電荷が、例えばフォ
トダイオード１１ａ〜１１ｄからＣＣＤチャネル２１に
矢印３１ａ〜３１ｄに示された如く一括転送され、続い
て当該電荷がＣＣＤチャネル２１の出力部に向けて矢印
４１に示す方向に転送され順次読み出される。2. Description of the Related Art Various structures have already been proposed for solid-state imaging devices, and some of them have been put into practical use. A conventional solid-state imaging device has a structure as shown in FIG. 4, for example. This figure is a diagram explaining the planar structure of a charge transfer (CCD) type two-dimensional solid-state imaging device.
2d is a photodiode that performs photoelectric conversion, 21, 22
indicates a CCD channel. The operation of the solid-state imaging device is roughly as follows. First, a charge corresponding to the intensity of the light pattern projected onto the solid-state imaging device is transferred to the photodiode 11a.
~11d, 12a~12d. After a predetermined period of time has elapsed, the charges accumulated in the photodiodes are collectively transferred from the photodiodes 11a to 11d to the CCD channel 21 as shown by arrows 31a to 31d, and then the charges are directed to the output section of the CCD channel 21. The data is transferred in the direction shown by the arrow 41 and read out sequentially.
【０００３】図５は、図４のＡＡ’における断面構造を
説明する図であり、図４に於て、１はｎ型半導体基板、
２はＰ型ウェル、３はｎ型不純物領域からなるフォトダ
イオード、４はｎ型不純物領域からなるＣＣＤチャネル
、５は分離用Ｐ＋ 領域、６は絶縁膜、７１は第１電極
、７２は第２電極、８は光を遮断する遮光膜、９はトラ
ンジスタのゲート部、１０は光路、をそれぞれ示す。FIG. 5 is a diagram illustrating a cross-sectional structure taken along line AA' in FIG. 4. In FIG. 4, 1 is an n-type semiconductor substrate;
2 is a P-type well, 3 is a photodiode made of an n-type impurity region, 4 is a CCD channel made of an n-type impurity region, 5 is a P+ region for isolation, 6 is an insulating film, 71 is a first electrode, and 72 is a second electrode. Reference numeral 8 indicates an electrode, a light shielding film that blocks light, 9 a gate portion of a transistor, and 10 an optical path.
【０００４】当該構造固体撮像装置による動作原理は次
の通りである。まず、フォトダイオード３に入射した光
により電荷が発生し、これがフォトダイオード３に蓄積
される。所定時間経過後に第１電極７１にパルス電圧を
印加しトランジスタのゲート部９を導通状態にすること
でフォトダイオード３内の蓄積電荷をＣＣＤチャネル４
に移す。しかる後にトランジスタのゲート部９が導通し
ない程度の低電圧パルス列を電極７１および７２に加え
、ＣＣＤチャネル内を電荷転送する。フォトダイオード
３の周囲部の電極７１，７２側壁部および電極７１，７
２の上部には絶縁膜６を介して遮光膜８が設けられ、フ
ォトダイオード以外の領域に光が入射するのを防いでい
る。The operating principle of this structural solid-state imaging device is as follows. First, light incident on the photodiode 3 generates charges, which are accumulated in the photodiode 3. After a predetermined time has elapsed, a pulse voltage is applied to the first electrode 71 to make the gate part 9 of the transistor conductive, thereby transferring the accumulated charge in the photodiode 3 to the CCD channel 4.
Move to. Thereafter, a low voltage pulse train is applied to the electrodes 71 and 72 such that the gate portion 9 of the transistor does not become conductive, thereby transferring charge within the CCD channel. Side wall portions of electrodes 71, 72 around photodiode 3 and electrodes 71, 7
A light shielding film 8 is provided on top of the photodiode 2 with an insulating film 6 interposed therebetween to prevent light from entering areas other than the photodiode.
【０００５】上述した固体撮像装置では、フォトダイオ
ード３に入る光は遮光膜８で規定されたフォトダイオー
ド開口部の範囲に限られる。ＣＣＤ型固体撮像装置では
、フォトダイオード３はＣＣＤチャネル４と同一平面上
に形成されるため、１画素のしめる面積に対するフォト
ダイオード開口面積（開口率）は高々３０％程度に制限
されてしまう。即ち、固体撮像装置に投影される光の３
０％が有効に利用されるにすぎない。これを改善する手
段として、フォトダイオード３の上部にマイクロレンズ
を設け集光することが行われている。図６はマイクロレ
ンズを設けたＣＣＤ型固体撮像装置の断面構造を説明す
る図であり、図５と同じ部分の断面を示す。図に於て、
６５は平坦化膜、１１はマイクロレンズを示す。マイク
ロレンズ１１に入射した光は、光路１０に示される如く
フォトダイオード３の開口部に集光される。即ち、レン
ズに入射する光の大部分がフォトダイオード３に入るた
め、マイクロレンズの径を大きくとれば固体撮像装置に
入射する光を有効に利用することが出来、実行的に開口
率を大きくすることができる。従来のレンズでは実行的
開口率を６０〜７５％、即ち、マイクロレンズを設ける
ことにより感度を２〜２．５倍に向上させる効果があっ
た。In the solid-state imaging device described above, the light entering the photodiode 3 is limited to the range of the photodiode opening defined by the light shielding film 8. In the CCD type solid-state imaging device, the photodiode 3 is formed on the same plane as the CCD channel 4, so the aperture area (aperture ratio) of the photodiode relative to the area covered by one pixel is limited to about 30% at most. In other words, 3 of the light projected onto the solid-state imaging device
Only 0% is used effectively. As a means to improve this, a microlens is provided above the photodiode 3 to condense light. FIG. 6 is a diagram illustrating a cross-sectional structure of a CCD solid-state imaging device provided with a microlens, and shows a cross-section of the same portion as FIG. 5. In FIG. In the figure,
65 is a flattening film, and 11 is a microlens. The light incident on the microlens 11 is focused on the opening of the photodiode 3 as shown by the optical path 10. In other words, most of the light that enters the lens enters the photodiode 3, so if the diameter of the microlens is made large, the light that enters the solid-state imaging device can be effectively used, effectively increasing the aperture ratio. be able to. Conventional lenses have an effective aperture ratio of 60 to 75%, that is, the provision of microlenses has the effect of improving sensitivity by 2 to 2.5 times.
【０００６】[0006]
【発明が解決しようとする課題】マイクロレンズの径を
大きくすれば、実行的な開口率を１００％近くに高める
ことは原理的には可能であるが、現状ではマイクロレン
ズの作り方の上で制約がある。図７は、マイクロレンズ
を作る手順を説明する図であり、図６における平坦化膜
６５を形成する以降の工程を示している。まず、遮光膜
や周辺部の配線を形成する工程まで完了した固体撮像装
置の表面に、平坦化剤（液体）を塗布し平坦化膜６５が
形成される（図７（ａ））。次に、マイクロレンズとな
る感光材料（フォトレジストなど）を塗布した後に、マ
スクを用いて露光を行いフォトレジストパターン１１０
を形成する（図７（ｂ））。しかる後に、ベーキングを
行い、フォトレジストパターンをリフローすることによ
り、マイクロレンズ１１を形成する（図７（ｃ））。[Problem to be solved by the invention] Although it is theoretically possible to increase the effective aperture ratio to nearly 100% by increasing the diameter of the microlens, there are currently restrictions on how to make the microlens. There is. FIG. 7 is a diagram illustrating the procedure for making a microlens, and shows the steps after forming the flattening film 65 in FIG. 6. First, a planarizing agent (liquid) is applied to the surface of the solid-state imaging device, which has undergone the process of forming a light-shielding film and peripheral wiring, to form a planarizing film 65 (FIG. 7(a)). Next, after applying a photosensitive material (such as photoresist) that will become the microlens, exposure is performed using a mask to create a photoresist pattern 110.
(Fig. 7(b)). Thereafter, baking is performed and the photoresist pattern is reflowed to form the microlens 11 (FIG. 7(c)).
【０００７】図８はマイクロレンズを形成するための他
の従来法を説明する図であり、６６はレンズ材料膜であ
る。当該法では平坦化膜６５の表面にレンズ材料膜６６
を設けたのちにフォトレジストパターン１１０を形成す
る（図８（ａ））。次にベーキングを行い、フォトレジ
ストパターン１１０をリフローすることによりレンズ形
状パターン１１を形成する（図８（ｂ））。しかるのち
にレンズ形状パターン１１をマスク材としてリアクティ
ブイオンエッチング法によりレンズ材料膜６６をエッチ
ングすることにより、レンズ形状パターン１１の形状が
レンズ材料膜６６に転写されレンズ１６が形成される（
図８（ｃ））。FIG. 8 is a diagram illustrating another conventional method for forming a microlens, and 66 is a lens material film. In this method, a lens material film 66 is formed on the surface of the flattening film 65.
After that, a photoresist pattern 110 is formed (FIG. 8(a)). Next, baking is performed and the photoresist pattern 110 is reflowed to form a lens-shaped pattern 11 (FIG. 8(b)). Thereafter, by etching the lens material film 66 using the lens shape pattern 11 as a mask material by a reactive ion etching method, the shape of the lens shape pattern 11 is transferred to the lens material film 66, and the lens 16 is formed (
Figure 8(c)).
【０００８】当該従来形成法では、フォトレジストを露
光する時のパターン間のスペースは、レンズ厚が２〜３
μｍと厚いために０．８〜１μｍ程度を形成するのが限
度である。２次元固体撮像装置の１画素のしめる面積を
、例えば５５μｍ２ とした時、マイクロレンズ間のス
ペースを１μｍにしたとすると、画素面積に対する実行
的な集光能力が、即ち開口率は高々７５％である。さら
に高感度化をめざして開口率を高めるとするならばレン
ズ間のスペースをさらに狭める必要があるが露光技術の
点で制約がある。即ち、上記した従来法では、現露光技
術ではこれ以上の開口率の向上は不可能であるという点
を有していた。さらに、今後の露光技術が進歩し０．７
〜０．５μｍのレンズ間スペースが解像できたとしても
実効的な開口率を１００％近くまで高めることは困難で
ある。なお、レンズパターン１１０をベーキングする条
件を選び、レンズパターンの先端部をパターン間の平坦
な部分にもリフローさせることにより、マイクロレンズ
間のスペースを短くすることは可能である。しかし、リ
フロー工程でレンズが近接するとその表面張力によりパ
ターンの先端部がくっつき合い、レンズ端部の形状が下
に凸の丸みをおびる。かかる形状はレンズの集光能力を
低下させるため好ましくない。In the conventional forming method, the space between the patterns when exposing the photoresist is such that the lens thickness is 2 to 3 mm.
Since it is as thick as .mu.m, the limit is about 0.8 to 1 .mu.m. If the area covered by one pixel of a two-dimensional solid-state imaging device is, for example, 55 μm2, and the space between the microlenses is 1 μm, then the effective light gathering ability for the pixel area, that is, the aperture ratio, is at most 75%. be. If the aperture ratio is to be increased with the aim of achieving even higher sensitivity, it is necessary to further narrow the space between the lenses, but there are limitations in terms of exposure technology. That is, the conventional method described above has the disadvantage that it is impossible to further improve the aperture ratio with the current exposure technology. Furthermore, as exposure technology advances in the future,
Even if an inter-lens space of ~0.5 μm can be resolved, it is difficult to increase the effective aperture ratio to nearly 100%. Note that it is possible to shorten the space between microlenses by selecting the conditions for baking the lens pattern 110 and reflowing the tip of the lens pattern also into the flat part between the patterns. However, when the lenses are brought close together during the reflow process, the tips of the patterns stick together due to surface tension, causing the edges of the lenses to take on a downwardly convex round shape. Such a shape is not preferable because it reduces the light gathering ability of the lens.
【０００９】[0009]
【課題を解決するための手段】本発明は、従来法で形成
したマイクロレンズの表面に均一な厚さのマイクロレン
ズカバー膜を２００℃以下の低温で数１０００オングス
トーロム程度の厚さに形成することにより、マイクロレ
ンズ間スペースを実効的に狭めるものである。本発明に
よれば、現状の露光技術を用いてマイクロレンズを形成
した上でマイクロレンズカバー膜を形成する工程を追加
しレンズ間スペースを原理的に零に近くすることが可能
であり、またレンズ間の形状をＶ字型に形成することが
できる。このため実効的開口率を１００％近くに高める
ことができる。[Means for Solving the Problems] The present invention forms a microlens cover film with a uniform thickness on the surface of a microlens formed by a conventional method at a low temperature of 200°C or less to a thickness of approximately several thousand angstroms. By doing so, the space between the microlenses is effectively narrowed. According to the present invention, it is possible to form microlenses using current exposure technology, and then add a step of forming a microlens cover film, thereby making it possible in principle to make the interlens space close to zero. The shape in between can be formed into a V-shape. Therefore, the effective aperture ratio can be increased to nearly 100%.
【００１０】0010
【実施例】以下、図面により本発明の実施例につき詳述
する。[Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
【００１１】図１は本発明一実施例になるマイクロレン
ズが設けられた固体撮像装置の断面構造を示しており、
図６と同じ部分の構造図を示す。図に於て、図６と同一
記号は同一機能を有する物質を示し、１２はマイクロレ
ンズカバー膜を示す。当該構造の固体撮像装置では、マ
イクロレンズ１１の表面にマイクロレンズカバー膜１２
が設けられており、この両者がレンズとして機能する。
マイクロレンズカバー膜１２を設けた場合にはレンズ間
に平坦な部分はなく、Ｖ字型となっている。このため、
当該構造の固体撮像装置はレンズ径が極めて大きく、入
射光に対する実効的な開口率が１００％近いという特徴
がある。FIG. 1 shows a cross-sectional structure of a solid-state imaging device provided with a microlens according to an embodiment of the present invention.
A structural diagram of the same part as FIG. 6 is shown. In the figure, the same symbols as in FIG. 6 indicate substances having the same functions, and 12 indicates a microlens cover film. In the solid-state imaging device having this structure, a microlens cover film 12 is provided on the surface of the microlens 11.
are provided, and both function as a lens. When the microlens cover film 12 is provided, there is no flat part between the lenses, and they are V-shaped. For this reason,
A solid-state imaging device with this structure has an extremely large lens diameter and is characterized by an effective aperture ratio of nearly 100% for incident light.
【００１２】図２は図１に示した固体撮像装置の形成方
法を説明する図であり、図１に示した平坦化膜６５を形
成する以降のレンズ形成工程を説明している。図に於て
、マイクロレンズ１１を形成するまでの工程は図７で説
明した従来法と全く同様にして形成される（図２（ｃ）
）。次に、マイクロレンズ１１および平坦化膜６５の表
面にマイクロレンズカバー膜１２を形成する（同図（ｄ
））。当該膜にはマイクロレンズの形状を忠実に反映さ
せる必要があり、膜圧均一性の良い化学気相成長法など
の手法で形成するのが望ましい。マイクロレンズ１１は
材質的に耐熱性が不充分であるため、化学気相成長は１
５０〜２００℃の温度で行う必要があり、この要求を満
足する手法としてはプラズマ方式の気相成長法が好まし
い。FIG. 2 is a diagram illustrating a method of forming the solid-state imaging device shown in FIG. 1, and explains the lens forming process after forming the flattening film 65 shown in FIG. 1. In the figure, the steps up to the formation of the microlens 11 are performed in exactly the same manner as the conventional method explained in FIG. 7 (FIG. 2(c)).
). Next, the microlens cover film 12 is formed on the surfaces of the microlens 11 and the flattening film 65 (see FIG.
)). The film needs to faithfully reflect the shape of the microlens, and is preferably formed using a method such as chemical vapor deposition that provides good film thickness uniformity. Since the microlens 11 is made of a material with insufficient heat resistance, chemical vapor deposition
It is necessary to carry out the process at a temperature of 50 to 200°C, and a plasma-based vapor phase growth method is preferable as a method that satisfies this requirement.
【００１３】図３はかかる気相成長法でＳｉＯ２ 膜を
形成する場合の膜堆積速度の結果を示している。ガスと
してはＳｉＨ４ とＯ２ を各々５０ＳＣＣＭ，５００
ＳＣＣＭ流し、圧力０．５Ｔｏｒｒ、プラズマ周波数５
０ＫＨｚ〜１ＭＨｚの条件での結果である。例えば、マ
イクロレンズ間の平坦部が１μｍの場合には、マイクロ
レンズカバー膜１２として０．５μｍの膜厚を設ければ
当該平坦部を零にすることができる。図３の結果によれ
ば１５０℃での膜堆積速度は７５０オングストローム／
分であり、０．５μｍの膜堆積に要する時間は７分弱と
実用上充分な速度である。当該法で形成したマイクロレ
ンズカバー膜１２のレンズ間の部分を観察すると良好な
Ｖ字型を程しており、集光効率は極めて良好であった。FIG. 3 shows the results of the film deposition rate when forming a SiO2 film by such a vapor phase growth method. As gases, SiH4 and O2 were used at 50 SCCM and 500 SCCM, respectively.
SCCM flow, pressure 0.5 Torr, plasma frequency 5
These are the results under the conditions of 0 KHz to 1 MHz. For example, if the flat portion between the microlenses is 1 μm, the flat portion can be made zero by providing the microlens cover film 12 with a film thickness of 0.5 μm. According to the results in Figure 3, the film deposition rate at 150°C is 750 angstroms/
The time required to deposit a 0.5 μm film is a little less than 7 minutes, which is a sufficient speed for practical use. When the part between the lenses of the microlens cover film 12 formed by this method was observed, it had a good V-shape, and the light collection efficiency was extremely good.
【００１４】なお、レンズの集光効率はレンズに入射す
る光を固体撮像装置のフォトダイオードに集光する割合
と定義される。従って集光効率はレンズ径，レンズの高
さ，平坦化膜の厚さに依存するため、これらを最適に選
ぶ必要がある。一例として、屈折率が１．６と１．５５
のレンズ材および平坦化膜を用いるとした時の最適数値
は、レンズ径６．５μ、レンズ間スペース０．８μ、レ
ンズ高さ１．６μ、平坦化膜の厚さ５．５μであり、屈
折率１．５４のレンズカバー膜を０．４μｍ設けて９５
％以上の集光効率を得た。Note that the light collection efficiency of a lens is defined as the ratio of light incident on the lens to the photodiode of the solid-state imaging device. Therefore, since the light collection efficiency depends on the lens diameter, lens height, and thickness of the flattening film, these must be selected optimally. As an example, the refractive index is 1.6 and 1.55
The optimum values when using lens material and flattening film are lens diameter 6.5μ, inter-lens space 0.8μ, lens height 1.6μ, and flattening film thickness 5.5μ. 95 by providing a lens cover film of 0.4 μm with a ratio of 1.54.
% or more of light collection efficiency was obtained.
【００１５】図９は本発明を実現するための他の手法を
説明する図である。図に於て、図８と同記号は同一機能
を有する物質を示す。当該例では、平坦化膜６５には有
機材料からなる膜を用い、レンズ材料膜６６にはＳｉＯ
２ 等の無機材料からなる膜を用いる。従って、フォト
レジストによるレンズパターン１１をマスクとして転写
されたレンズ１６には無機材料から形成される（図９（
ｃ））。次に、レンズ１６表面にのみ選択的にＳｉＯ２
膜を堆積する。かかる膜成長法としては、例えば室温
・液相成長を適用できる。即ち、Ｈ２ＳｉＦ６ 水溶液
中にＳｉＯ２ 粉末を溶解し飽和状態とする。かかる溶
液に図９（ｃ）に示す構造基板を入れたのちにほう酸（
Ｈ３ ＢＯ３ ）水溶液を添加しＳｉＯ２ を過飽とさ
せることでレンズ１６の表面にＳｉＯ２ を堆積させる
。この時、有機材料からなる平坦化膜６５の表面にはＳ
ｉＯ２ は形成されず、レンズ１６の表面にのみＳｉＯ
２ が堆積され、図９（ｄ）に示すマイクロレンズカバ
ー膜１２が形成される。FIG. 9 is a diagram illustrating another method for implementing the present invention. In the figure, the same symbols as in FIG. 8 indicate substances having the same functions. In this example, the flattening film 65 is made of an organic material, and the lens material film 66 is made of SiO.
A membrane made of an inorganic material such as 2 is used. Therefore, the lens 16 transferred using the photoresist lens pattern 11 as a mask is formed of an inorganic material (see FIG.
c)). Next, SiO2 is selectively applied only to the surface of the lens 16.
Deposit the film. As such a film growth method, for example, room temperature/liquid phase growth can be applied. That is, SiO2 powder is dissolved in an aqueous H2SiF6 solution to bring it into a saturated state. After placing the structural substrate shown in FIG. 9(c) in such a solution, boric acid (
SiO2 is deposited on the surface of the lens 16 by adding an aqueous solution (H3BO3) to supersaturate the SiO2. At this time, the surface of the planarization film 65 made of an organic material is S
No iO2 is formed, and SiO2 is formed only on the surface of the lens 16.
2 is deposited to form the microlens cover film 12 shown in FIG. 9(d).
【００１６】マイクロレンズカバー膜１２の材質として
は、有機材料膜を用いても、あるいはＳｉＯ２ ・Ｓｉ
３ Ｎ４ ・ＳｉＯＮなどの無機材料膜を用いてもその
選択は自由であるが、機械的強度の点では無機材料膜を
用いるのが望ましい。なお、マイクロレンズ１１の屈折
率は１．６〜１．７程度であるのに対し、ＳｉＯ２ で
は１．４５、Ｓｉ３ Ｎ４ では２．０である。マイク
ロレンズ１１とマイクロレンズカバー膜１２との屈折率
差が大きいとマイクロレンズの焦点の設計が困難となる
。この点ではＳｉＯＮは１．６〜１．８程度の範囲で選
択が可能であるため好ましい材料である。しかし、一方
では屈折率の差を積極的に利用して色収差を低減したレ
ンズを実現することも出来る。さらに、マイクロレンズ
カバー膜１２の表面に反射防止膜を設けることにより固
体撮像装置に入射する光の反射を防止する手段を適用す
るのも一法であり、反射にはゴーストの発生を防止する
と共に、光に対する感度をさらに改善する効果があり好
ましい結果を得る。As the material of the microlens cover film 12, an organic material film or SiO2/Si
Although it is possible to use an inorganic material film such as 3 N4 .SiON, it is preferable to use an inorganic material film in terms of mechanical strength. Note that the refractive index of the microlens 11 is about 1.6 to 1.7, whereas it is 1.45 for SiO2 and 2.0 for Si3N4. If the difference in refractive index between the microlens 11 and the microlens cover film 12 is large, it becomes difficult to design the focal point of the microlens. In this respect, SiON is a preferable material because it can be selected from a range of about 1.6 to 1.8. However, on the other hand, it is also possible to actively utilize the difference in refractive index to realize a lens with reduced chromatic aberration. Furthermore, one method is to apply a means to prevent the reflection of light incident on the solid-state imaging device by providing an anti-reflection film on the surface of the microlens cover film 12. , which has the effect of further improving the sensitivity to light and yields favorable results.
【００１７】[0017]
【発明の効果】以上説明したように、本発明はマイクロ
レンズが設けられた固体撮像装置の表面にマイクロレン
ズカバー膜を設けレンズ径を拡大することにより、入射
光に対する開口率を実効的に１００％近くに向上出来、
従って光感度を大幅に改善する効果を有する。さらに、
マイクロレンズカバー膜として無機材料を選ぶことによ
りレンズの機械的強度を高められる効果がある。また、
マイクロレンズカバー膜の屈折率を選ぶことにより色収
差の少いレンズを実現することが出来るため、感度の波
長依存性を改善できる効果を持つ。さらに、マイクロレ
ンズカバー膜表面に反射防止膜を設けることにより、表
面反射により発生するゴーストを除去すると共に、感度
をさらに向上できる効果を有する。As explained above, the present invention provides a microlens cover film on the surface of a solid-state imaging device provided with microlenses to enlarge the lens diameter, thereby effectively increasing the aperture ratio to 100% for incident light. It was possible to improve close to %,
Therefore, it has the effect of significantly improving photosensitivity. moreover,
Choosing an inorganic material for the microlens cover film has the effect of increasing the mechanical strength of the lens. Also,
By selecting the refractive index of the microlens cover film, it is possible to create a lens with less chromatic aberration, which has the effect of improving the wavelength dependence of sensitivity. Furthermore, by providing an antireflection film on the surface of the microlens cover film, ghosts generated by surface reflection can be removed, and sensitivity can be further improved.
【図１】本発明一実施例を示す断面図である。FIG. 1 is a sectional view showing one embodiment of the present invention.
【図２】図１の装置の製造工程を部分的に示す断面図で
ある。FIG. 2 is a cross-sectional view partially showing the manufacturing process of the device of FIG. 1;
【図３】膜の堆積速度を示す図である。FIG. 3 is a diagram showing the deposition rate of a film.
【図４】固体撮像装置の原理を示す図である。FIG. 4 is a diagram showing the principle of a solid-state imaging device.
【図５】従来例を示す断面図である。FIG. 5 is a sectional view showing a conventional example.
【図６】他の従来例を示す断面図である。FIG. 6 is a sectional view showing another conventional example.
【図７】従来例の方法を示す断面図である。FIG. 7 is a sectional view showing a conventional method.
【図８】他の従来例の方法を示す断面図である。FIG. 8 is a sectional view showing another conventional method.
【図９】本発明他の実施例の方法を示す断面図である。FIG. 9 is a cross-sectional view showing a method according to another embodiment of the present invention.
１ ｎ型半導体基板 ２ Ｐ型ウェル ３ フォトダイオード ４ ＣＣＤチャネル ５ Ｐ＋ 領域 ６ 絶縁膜 ６５ 平坦化膜 ７１，７２ 電極 ８ 遮光膜 １０ 光路 １１，１６ マイクロレンズ １２ マイクロレンズカバー膜 1 N-type semiconductor substrate 2 P-type well 3 Photodiode 4 CCD channel 5 P+ area 6 Insulating film 65 Planarization film 71, 72 Electrode 8. Light shielding film 10 Optical path 11, 16 Micro lens 12 Microlens cover film
Claims (5)
ズと、該マイクロレンズの表面を含む装置の表面に設け
られたマイクロレンズカバー膜とで構成されるレンズに
おいて、隣りあうレンズ間部分の形状がＶ字型に形成さ
れることを特徴とした固体撮像装置。Claim 1: In a lens composed of a microlens provided above a pixel and a microlens cover film provided on the surface of the device including the surface of the microlens, the shape of the portion between adjacent lenses is A solid-state imaging device characterized by being formed in a V-shape.
、該マイクロレンズの表面を含む装置の表面に設けられ
た屈折率の異なる複数層のマイクロレンズカバー膜とで
色収差を除去したレンズを構成することを特徴とした固
体撮像装置。2. A lens in which chromatic aberration is removed is constituted by a microlens provided on a pixel and a plurality of layers of microlens cover films having different refractive indexes provided on the surface of the device including the surface of the microlens. A solid-state imaging device characterized by:
、該マイクロレンズの表面を含む装置の表面に設けられ
たマイクロレンズカバー膜とで構成されたレンズの表面
に、反射防止膜が設けられることを特徴とした固体撮像
装置。3. An antireflection film is provided on the surface of the lens, which is composed of a microlens provided on the pixel and a microlens cover film provided on the surface of the device including the surface of the microlens. A solid-state imaging device featuring:
る工程と、該マイクロレンズ表面を含む装置の表面に前
記マイクロレンズの径を拡大し、かつ隣り合うレンズ間
部分の形状がＶ字型とするべくマイクロレンズカバー膜
を設ける工程とを含むことを特徴とした固体撮像装置の
製造方法。4. Forming a microlens above a pixel, enlarging the diameter of the microlens on the surface of the device including the microlens surface, and making the shape of the portion between adjacent lenses V-shaped. A method for manufacturing a solid-state imaging device, comprising the step of providing a microlens cover film.
ロレンズの表面にのみ選択的に設けられることを特徴と
した請求項４記載の固体撮像装置の製造方法。5. The method of manufacturing a solid-state imaging device according to claim 4, wherein the microlens cover film is selectively provided only on the surface of the microlens.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10726091A JP3166199B2 (en) | 1990-05-16 | 1991-05-13 | Solid-state imaging device and method of manufacturing the same |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2-126151 | 1990-05-16 | ||
| JP12615190 | 1990-05-16 | ||
| JP10726091A JP3166199B2 (en) | 1990-05-16 | 1991-05-13 | Solid-state imaging device and method of manufacturing the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH04226073A true JPH04226073A (en) | 1992-08-14 |
| JP3166199B2 JP3166199B2 (en) | 2001-05-14 |
Family
ID=26447301
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10726091A Expired - Lifetime JP3166199B2 (en) | 1990-05-16 | 1991-05-13 | Solid-state imaging device and method of manufacturing the same |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3166199B2 (en) |
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