JPH03212975A - Image sensor - Google Patents
Image sensorInfo
- Publication number
- JPH03212975A JPH03212975A JP2008063A JP806390A JPH03212975A JP H03212975 A JPH03212975 A JP H03212975A JP 2008063 A JP2008063 A JP 2008063A JP 806390 A JP806390 A JP 806390A JP H03212975 A JPH03212975 A JP H03212975A
- Authority
- JP
- Japan
- Prior art keywords
- electrode
- photoconductive layer
- image sensor
- receiving element
- layer
- 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.)
- Pending
Links
- 239000000758 substrate Substances 0.000 claims abstract description 11
- 239000011521 glass Substances 0.000 abstract description 6
- 238000000034 method Methods 0.000 abstract description 6
- 238000001755 magnetron sputter deposition Methods 0.000 abstract description 4
- 238000000059 patterning Methods 0.000 abstract description 4
- 230000035945 sensitivity Effects 0.000 abstract description 3
- 238000005268 plasma chemical vapour deposition Methods 0.000 abstract 1
- 229910052751 metal Inorganic materials 0.000 description 13
- 239000002184 metal Substances 0.000 description 13
- 229910052782 aluminium Inorganic materials 0.000 description 8
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 8
- 239000011651 chromium Substances 0.000 description 8
- 238000011109 contamination Methods 0.000 description 7
- 239000010408 film Substances 0.000 description 7
- 238000004519 manufacturing process Methods 0.000 description 7
- 238000000206 photolithography Methods 0.000 description 6
- 239000007789 gas Substances 0.000 description 5
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 4
- 229910021417 amorphous silicon Inorganic materials 0.000 description 4
- 229910052804 chromium Inorganic materials 0.000 description 4
- 238000001312 dry etching Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- TXEYQDLBPFQVAA-UHFFFAOYSA-N tetrafluoromethane Chemical compound FC(F)(F)F TXEYQDLBPFQVAA-UHFFFAOYSA-N 0.000 description 4
- 239000004642 Polyimide Substances 0.000 description 3
- 229920001721 polyimide Polymers 0.000 description 3
- 229910021586 Nickel(II) chloride Inorganic materials 0.000 description 2
- 238000000137 annealing Methods 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 238000000151 deposition Methods 0.000 description 2
- 230000008021 deposition Effects 0.000 description 2
- AMGQUBHHOARCQH-UHFFFAOYSA-N indium;oxotin Chemical compound [In].[Sn]=O AMGQUBHHOARCQH-UHFFFAOYSA-N 0.000 description 2
- QMMRZOWCJAIUJA-UHFFFAOYSA-L nickel dichloride Chemical compound Cl[Ni]Cl QMMRZOWCJAIUJA-UHFFFAOYSA-L 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 230000002093 peripheral effect Effects 0.000 description 2
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- AQCDIIAORKRFCD-UHFFFAOYSA-N cadmium selenide Chemical compound [Cd]=[Se] AQCDIIAORKRFCD-UHFFFAOYSA-N 0.000 description 1
- UHYPYGJEEGLRJD-UHFFFAOYSA-N cadmium(2+);selenium(2-) Chemical compound [Se-2].[Cd+2] UHYPYGJEEGLRJD-UHFFFAOYSA-N 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 229910000077 silane Inorganic materials 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
Landscapes
- Solid State Image Pick-Up Elements (AREA)
- Transforming Light Signals Into Electric Signals (AREA)
- Facsimile Heads (AREA)
Abstract
Description
【発明の詳細な説明】
（産業上の利用分野）
本発明はファクシミリやスキャナ等に用いられるイメー
ジセンサに係り、特に明暗電流比（Ｓ／Ｎ比）を向上さ
せる受光素子を有するイメージセンサに関する。DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an image sensor used in facsimile machines, scanners, etc., and particularly relates to an image sensor having a light receiving element that improves the brightness/dark current ratio (S/N ratio).
（従来の技術）
従来のイメージセンサとしては、受光素子の集合体で原
稿幅と同じ幅の受光素子アレイを有し、原稿と密着して
用いられる密着型イメージセンサがあった。(Prior Art) As a conventional image sensor, there is a contact type image sensor which is an assembly of light receiving elements and has a light receiving element array having the same width as the width of the original, and is used in close contact with the original.
この密着型イメージセンサにおける受光素子の構成は、
光導電層として水素化アモルファスシリコン（ａ−３ｔ
：Ｈ）を用い、これを金属電極と透明電極とで挟んだサ
ンドイッチ構造のものであり、特に製造上困難であると
の理由から通常は透明電極側を共通電極とし、金属電極
を個別電極とする構成が採られていた。The configuration of the light receiving element in this contact type image sensor is as follows:
Hydrogenated amorphous silicon (a-3t
:H), which has a sandwich structure sandwiched between a metal electrode and a transparent electrode.Because it is particularly difficult to manufacture, the transparent electrode side is usually used as a common electrode, and the metal electrodes are used as individual electrodes. A configuration was adopted.
ところで、上記のサンドイッチ構造の受光素子において
は、光導電層が個別化していないために隣接ビットでの
干渉が起こり、出力の均一化が図れず、良好なダイオー
ド特性を得ることができないとの問題点があった。By the way, in the above-mentioned sandwich structure photodetector, since the photoconductive layer is not individualized, interference occurs between adjacent bits, making it impossible to equalize the output and obtain good diode characteristics. There was a point.
そこで、金属電極を共通電極とし、透明電極を個別電極
とし、各受光素子毎のばらつきを少なくするために、更
に光導電層をも個別化する受光素子の構成が考えられた
。このように、透明電極と同じ様に光導電層を個別化す
れば、光の回り込みによる漏れ電流が抑制され、イメー
ジセンサの解像度を向上される。Therefore, a configuration of a light receiving element was devised in which the metal electrode is used as a common electrode, the transparent electrode is used as an individual electrode, and the photoconductive layer is also made individual in order to reduce variations among each light receiving element. In this way, if the photoconductive layer is made individual in the same way as the transparent electrode, leakage current due to the wraparound of light can be suppressed, and the resolution of the image sensor can be improved.
ここで、透明電極を共通電極とする受光素子の構成を第
４図を使って具体的に説明すると、ガラス等の絶縁性の
基板１上に、下部電極２として、帯状をなして一体に形
成されたクロム（Ｃｒ）層からなる金属電極と、各素子
毎に分割形成されたａ−３ｔ：Ｈ層からなる光導電層３
と、同様に分割形成された酸化インジウム・スズ（ＩＴ
Ｏ）層からなる上部電極４の透明電極が順次積層され、
受光素子全体を覆うようにポリイミド等の絶縁層７が形
成され、下部電極２の金属電極に一定の電位がかかるよ
うになっており、上部電極４の透明電極からはアルミニ
ウム（ＡＩ）等の配線５ａが絶縁層７のコンタクト用ｖ
ｉａホール８ａから導き出され、光電変換された電荷を
読み取るようになっている。Here, the structure of a light receiving element using a transparent electrode as a common electrode will be explained in detail using FIG. A metal electrode consisting of a chromium (Cr) layer and a photoconductive layer 3 consisting of an a-3t:H layer divided for each element.
and indium tin oxide (IT
O) Transparent electrodes of the upper electrode 4 consisting of layers are sequentially laminated,
An insulating layer 7 made of polyimide or the like is formed to cover the entire light-receiving element, and a certain potential is applied to the metal electrode of the lower electrode 2, and a wiring made of aluminum (AI) or the like is connected from the transparent electrode of the upper electrode 4. 5a is v for contact of insulating layer 7
The charge led out from the ia hole 8a and subjected to photoelectric conversion is read.
次に、このイメージセンサの受光素子の製造方法につい
て説明すると、ガラス等の基板１上にスパッタリング法
により膜厚的１０００〜１５００へのクロム層を着膜し
、これを帯状にバターニングし、下部電極２となる共通
電極としての金属電極を形成する。そして、プラズマＣ
ＶＤ法により膜厚的１〜２μｍでａ−Ｓｔ：Ｈ層を堆積
する。Next, to explain the manufacturing method of the light receiving element of this image sensor, a chromium layer with a thickness of 1000 to 1500 mm is deposited on a substrate 1 made of glass or the like by sputtering method, and this is patterned into a band shape. A metal electrode is formed as a common electrode to become electrode 2. And plasma C
An a-St:H layer is deposited to a thickness of 1 to 2 μm using the VD method.
この時の堆積条件は、シラン（ＳｉＨ，）ガスを原料ガ
スとし、流量が２００〜５００ ｓｅｃ＋ａ、圧力が０
． ２〜０． ５Ｔｏｒｒ、基板温度が１５０〜２５０
℃、ＲＦパワーが８０〜１５０ ｍＷ／ｃｄ、時間が３
０〜６０分とする。次に、ＤＣマグネトロンスパッタ法
により膜厚的８０ＯＡでＩＴＯを成膜した後、レジスト
を塗布しフォトリソエツチング法によりパターニングし
、上部電極４となる個別電極としての透明電極を形成す
る。更にレジストパターンをそのままにし、これをマス
クとしてテトラフルオルメタン（ＣＦ、）と酸素（０２
）との混合ガスを用いて前記ａ−８ｉ：Ｈ層をエツチン
グし、個別に分割された光導電層３を形成する。The deposition conditions at this time were: silane (SiH,) gas was used as the raw material gas, the flow rate was 200 to 500 sec+a, and the pressure was 0.
．． 2-0. 5 Torr, substrate temperature 150-250
°C, RF power 80-150 mW/cd, time 3
0 to 60 minutes. Next, after forming an ITO film with a thickness of 80 OA by DC magnetron sputtering, a resist is applied and patterned by photolithography to form transparent electrodes as individual electrodes that will become the upper electrodes 4. Furthermore, leaving the resist pattern as it is and using it as a mask, tetrafluoromethane (CF) and oxygen (02
) is used to etch the a-8i:H layer to form individually divided photoconductive layers 3.
そして、レジストを剥離した後、大気中で３０分間２０
０℃でアニール処理を行う。そして受光素子全体にポリ
イミド等の絶縁層７を塗布し、ベクして、フォトリソエ
ツチングにて上部電極４から配線５ａを導き出すコンタ
クト用ｖｉａホール８ａを設け、更にアルミニウム（Ａ
Ｉ） ヲ着膜してフォトリソエツチングでバターニン
グして、配線５ａのパターンを形成する。このようにし
て、イメージセンサの受光素子が完成する（特開昭６３
−６７７７２号公報参照）。After peeling off the resist, it was exposed to air for 30 minutes.
Annealing treatment is performed at 0°C. Then, an insulating layer 7 made of polyimide or the like is coated over the entire photodetector, and a contact via hole 8a is formed by photolithography to lead out the wiring 5a from the upper electrode 4.
I) A film is deposited and patterned by photolithography to form a pattern for the wiring 5a. In this way, the light receiving element of the image sensor is completed (Japanese Unexamined Patent Publication No. 63
(Refer to Publication No.-67772).
（発明が解決しようとする課題）
しかしながら、上記のようなイメージセンサの構成にお
いて、光導電層３をパターニングする際に、ドライエツ
チングが行われるため、個別化した光導電層３の特に側
面にドライエツチングによる汚染やダメージが起ったり
、またレジスト剥離時またはＩＴＯのウェット処理時に
汚染が起ったりする。つまり、ダメージとは、ドライエ
ツチング時に光導電層３の側面のａ−３ｉ：Ｈがプラズ
マ状態にさらされると、ａ−５ｉ：ＨのＨの結合が切ら
れてａ−Ｓｉとなる場合があり、バンド間の準位が不完
全なものになり、光を受光しなくても電荷を発生させて
しまい、光導電層３の側面の特性を悪化させ、電流がリ
ークし易い構造になってしまう。また、ドライエツチン
グまたはウェット処理による汚染により、ガスの残留物
やその他の不純物等が光導電層３の側面に付着して電流
のリーク経路が形成されて、リークし易い構造になる恐
れがある。その結果、受光素子における暗電流が上昇し
て良好な明暗電流比（Ｓ／Ｎ比）が得られないとの問題
点があった。(Problem to be Solved by the Invention) However, in the configuration of the image sensor as described above, dry etching is performed when patterning the photoconductive layer 3. Contamination and damage may occur due to etching, and contamination may occur during resist stripping or wet processing of ITO. In other words, damage means that when a-3i:H on the side surface of the photoconductive layer 3 is exposed to a plasma state during dry etching, the H bond of a-5i:H may be broken and become a-Si. , the level between the bands becomes incomplete, and charges are generated even when no light is received, which deteriorates the characteristics of the side surfaces of the photoconductive layer 3 and creates a structure where current easily leaks. . Further, due to contamination caused by dry etching or wet processing, gas residues and other impurities may adhere to the side surfaces of the photoconductive layer 3, forming a current leak path, resulting in a structure prone to leaks. As a result, there is a problem in that the dark current in the light-receiving element increases, making it impossible to obtain a good bright-to-dark current ratio (S/N ratio).
本発明は上記実情に鑑みてなされたもので、イメージセ
ンサの受光素子において、光導電層の側面で起るリーク
電流成分を取り除き、良好な明暗電流比（Ｓ／Ｎ比）を
得ることができる受光素子を有するイメージセンサを提
供することを目的とする。The present invention has been made in view of the above-mentioned circumstances, and it is possible to remove the leakage current component occurring on the side surface of the photoconductive layer in the light receiving element of an image sensor, and to obtain a good bright-to-dark current ratio (S/N ratio). An object of the present invention is to provide an image sensor having a light receiving element.
（課題を解決するための手段）
上記従来例の問題点を解決するための本発明は、基板上
に形成された共通電極となる下部電極と、前記下部電極
上に画素毎に個別化した光導電層と、前記光導電層上に
前記各光導電層に対応する上部電極を順次積層した受光
素子を有するイメージセンサにおいて、前記各光導電層
の表面より小さい形状にて前記各上部電極を形成し、前
記各上部電極を取り囲むように前記各光導電層上にガー
ド電極を設けたことを特徴としている。(Means for Solving the Problems) The present invention for solving the problems of the conventional example has a lower electrode formed on a substrate as a common electrode, and an individual light beam for each pixel on the lower electrode. In an image sensor having a light receiving element in which a conductive layer and an upper electrode corresponding to each of the photoconductive layers are sequentially laminated on the photoconductive layer, each of the upper electrodes is formed in a shape smaller than the surface of each of the photoconductive layers. The method is characterized in that a guard electrode is provided on each of the photoconductive layers so as to surround each of the upper electrodes.
（作用）
本発明によれば、イメージセンサにおける受光素子の光
導電層を個別化したので、光導電層の側面にて製造工程
上起ったダメージや汚染により光導電層の側面で電流が
リークし易い構造となるが、上部電極を取り囲むように
光導電層の上にガード電極を設け、光導電層側面を流れ
るリーク電流をこのガード電極から逃がすようにしてい
るので、光導電層中を流れる純粋な電流成分と、光導電
層側面を流れるリーク電流を含む電流成分とを分けるこ
とができ、光導電層中において受光素子に光が照射した
際に発生する光電流のみを読み出すことができるので、
良好な明暗電流比（Ｓ／Ｎ比）を得ることができる。(Function) According to the present invention, since the photoconductive layer of the light-receiving element in the image sensor is individualized, current leaks from the side surface of the photoconductive layer due to damage or contamination that occurs during the manufacturing process. However, since a guard electrode is provided on the photoconductive layer so as to surround the upper electrode, and the leakage current flowing on the side surface of the photoconductive layer is allowed to escape from this guard electrode, the leakage current flowing through the photoconductive layer is It is possible to separate the pure current component from the current component that includes leakage current flowing on the side surface of the photoconductive layer, and it is possible to read out only the photocurrent that occurs when the photodetector in the photoconductive layer is irradiated with light. ,
A good bright/dark current ratio (S/N ratio) can be obtained.
（実施例）
本発明の一実施例について図面を参照しながら説明する
。(Example) An example of the present invention will be described with reference to the drawings.
第１図（ａ）は、本発明の一実施例に係るイメージセン
サの受光素子の平面説明図、第１図（ｂ）は、第１図（
ａＪのＡ−Ａ’部分の断面説明図である。また、第４図
と同様の構成をとる部分については同一の符号を使って
説明する。FIG. 1(a) is a plan view of a light receiving element of an image sensor according to an embodiment of the present invention, and FIG. 1(b) is a plan view of a light receiving element of an image sensor according to an embodiment of the present invention.
It is a cross-sectional explanatory view of the AA' part of aJ. Also, parts having the same configuration as in FIG. 4 will be described using the same reference numerals.
イメージセンサは、ガラス等の絶縁性の基板１上に並設
された複数個のサンドイッチ型の受光素子（フォトダイ
オード）からなる長尺状の受光素子アレイと、各受光素
子にそれぞれ接続された駆動回路から構成される。各受
光素子に発生した電荷は、時系列的に駆動回路にて画像
信号として出力される。The image sensor includes a long light-receiving element array consisting of a plurality of sandwich-type light-receiving elements (photodiodes) arranged in parallel on an insulating substrate 1 made of glass or the like, and a drive connected to each light-receiving element. Consists of circuits. The charges generated in each light receiving element are outputted as an image signal by a drive circuit in time series.
受光素子は、第１図（ａ）（ｂ）の平面説明図と断面説
明図に示すように、ガラス等の基板１上に共通電極とな
るクロム（Ｃｒ）等による金属電極の下部電極２と、水
素化アモルファスシリコン（ａ−３ｉ：Ｈ）から成る光
導電層３と、酸化インジウム・スズ（ＩＴＯ）から成る
透明電極の上部電極４とが順次積層するサンドイッチ型
を構成している。尚、ここでは金属電極の下部電極２は
主走査方向に帯状に形成され、下部電極２の上に光導電
層３が主走査方向に離散的に分割して形成され、同様に
上部電極４の透明電極も主走査方向に離散的に分割して
形成されることにより、光導電層３を金属電極の下部電
極２と透明電極の上部電極４とで挟んだ部分が各受光素
子を構成し、その集まりが受光素子アレイを形成してい
る。As shown in the plan view and cross-sectional view of FIGS. 1(a) and 1(b), the light-receiving element includes a substrate 1 made of glass or the like, and a lower electrode 2 made of metal such as chromium (Cr) serving as a common electrode. A photoconductive layer 3 made of hydrogenated amorphous silicon (a-3i:H) and a transparent upper electrode 4 made of indium tin oxide (ITO) are successively laminated to form a sandwich type. In this case, the lower electrode 2 of the metal electrode is formed in a strip shape in the main scanning direction, and the photoconductive layer 3 is formed on the lower electrode 2 by being divided into discrete parts in the main scanning direction. The transparent electrodes are also formed discretely in the main scanning direction, so that the portion of the photoconductive layer 3 sandwiched between the lower electrode 2 of the metal electrode and the upper electrode 4 of the transparent electrode constitutes each light receiving element. A collection of these forms a light receiving element array.
特に、各個別化された上部電極４の透明電極は、各個別
化された光導電層３よりひとまわり小さく個別化された
光導電層３の周辺部分が露出するよう形成され、当該光
導電層３の周辺部分上部に上部電極４の透明電極と同じ
ＩＴＯで、透明電極を囲み、透明電極に接続しないよう
に間隔を置いてリング状でガード電極６が形成されてい
る。In particular, the transparent electrode of each individualized upper electrode 4 is formed so that the peripheral portion of the individualized photoconductive layer 3, which is one size smaller than each individualized photoconductive layer 3, is exposed. A ring-shaped guard electrode 6 is formed on the upper peripheral portion of 3, made of the same ITO as the transparent electrode of the upper electrode 4, surrounding the transparent electrode and spaced apart from the transparent electrode so as not to be connected to the transparent electrode.
また、受光素子全体を覆うように透明な絶縁層７が形成
され、上部電極４とガード電極６に配線５ａ、５ｂをそ
れぞれ接続するために当該絶縁層７にコンタクト用ｖｉ
ａホール８ａｓ ８ｂが設けられている。そして離散的
に分割形成された上部電極４の一端からはアルミニウム
（ＡＩ）等の配線５ａが引き出され、電荷転送部の薄膜
トランジスタに接続されている。そして、ガード電極６
の一端からもアルミニウム（ＡＩ）等の配線５ｂが引き
出され、接地されている。配線５ａと配線５ｂとは、例
えば絶縁層（図示せず）を介在させて多層配線構造とし
ている。また、受光素子において、水素化アモルファス
シリコンの代わりに、ＣｄＳｅ （カドミウムセレン）
等を光導電層とすることも可能である。Further, a transparent insulating layer 7 is formed so as to cover the entire light receiving element, and a contact via is provided on the insulating layer 7 to connect the wirings 5a and 5b to the upper electrode 4 and the guard electrode 6, respectively.
A-holes 8as and 8b are provided. A wiring 5a made of aluminum (AI) or the like is drawn out from one end of the upper electrode 4, which is formed in a discrete manner, and is connected to a thin film transistor of the charge transfer section. And guard electrode 6
A wiring 5b made of aluminum (AI) or the like is also drawn out from one end and grounded. The wiring 5a and the wiring 5b have a multilayer wiring structure, for example, with an insulating layer (not shown) interposed therebetween. In addition, in the photodetector, CdSe (cadmium selenium) is used instead of hydrogenated amorphous silicon.
It is also possible to use the photoconductive layer as a photoconductive layer.
次に、本発明に係る一実施例のイメージセンサの受光素
子の製造方法について説明する。Next, a method for manufacturing a light receiving element of an image sensor according to an embodiment of the present invention will be described.
まず、ガラス等の基板１上に下部電極２となる金属電極
を形成するために、ＤＣマグネトロンスパッタ法により
Ｃｒを厚さ約１０００〜１５００人で着膜し、帯状にバ
ターニングする。尚、この金属としてはＣｒの他に、ニ
ッケルクロク（ＮｉＣ「）、タングステン（Ｗ）、タン
タル（Ｔａ）等であっても構わない。First, in order to form a metal electrode that will become the lower electrode 2 on a substrate 1 made of glass or the like, a Cr film is deposited to a thickness of about 1000 to 1500 by DC magnetron sputtering and patterned into a band shape. In addition to Cr, this metal may be nickel chloride (NiC), tungsten (W), tantalum (Ta), or the like.
次に、光導電層３の半導体層ａ−５ｉ：Ｈをブラダ７Ｃ
ＶＤ （Ｐ−ＣＶＤ）法で膜厚的１〜２μｍで着膜する
。形成の条件は、ＳｉＨ，ガスを用い、流量２００〜５
００ｓｃｃｌｌ１１圧力０．２〜０゜５ Ｔｏｒｒ、基
板温度１５０〜２５０℃、ＲＦパワー８０〜１５０ ｍ
Ｗ／ｃｊ、着膜時間３０〜６０分である。Next, the semiconductor layer a-5i:H of the photoconductive layer 3 is transferred to the bladder 7C.
A film is deposited to a thickness of 1 to 2 μm using the VD (P-CVD) method. The formation conditions are SiH gas and flow rate 200~5.
00sccll11 Pressure 0.2~0°5 Torr, Substrate temperature 150~250℃, RF power 80~150 m
W/cj, film deposition time is 30 to 60 minutes.
次に、光導電層３の上に上部電極４の透明電極を形成す
るために、ＤＣマグネトロンスパッタ法により膜厚的８
０ＯＡでＩＴＯを着膜する。その後、レジストを塗布し
フォトリソエツチング法により露光、現像して第１図に
示すような形状にバターニングし、個別電極としての透
明電極の上部電極４を形成する。この時、上部電極４部
分を囲むように、ＩＴＯを用いてガード電極６の形状も
同時にバターニングによって形成する。Next, in order to form a transparent electrode of the upper electrode 4 on the photoconductive layer 3, a film thickness of 8.
ITO is deposited at 0OA. Thereafter, a resist is applied, exposed to light by photolithography, developed, and patterned into the shape shown in FIG. 1 to form the upper electrode 4 of the transparent electrode as an individual electrode. At this time, the shape of the guard electrode 6 is also formed by patterning using ITO so as to surround the upper electrode 4 portion.
更にレジストを塗布して、ＩＴＯのパターンを形成した
フォトリソマスクとは別のマスクを用い、テトラフルオ
ルメタン（ＣＦ、）と酸素（０２）との混合ガスを用い
て前記ａ−８ｉ：Ｈ層をドライエツチングし、個別に分
割された光導電層３を形成する。この場合、上記のガー
ド電極６の外側で光導電層３を個別化するようにする。Furthermore, a resist was applied, and using a mask different from the photolithographic mask in which the ITO pattern was formed, the a-8i:H layer was removed using a mixed gas of tetrafluoromethane (CF) and oxygen (02). is dry-etched to form individually divided photoconductive layers 3. In this case, the photoconductive layer 3 is separated outside the guard electrode 6 described above.
そして、レジストを剥離した後、大気中で３０分間２０
０℃でアニール処理を行う。After peeling off the resist, it was exposed to air for 30 minutes.
Annealing treatment is performed at 0°C.
さらに、ポリイミド等の透明な絶縁層７を塗布し、ベー
クし、上部電極４およびガード電極６から配線５ｇ、５
ｂがそれぞれ引き出せるようコンタクト用ｖｉａホール
８ａ、８ｂを形成するためにフォトリソ工程でバターニ
ングを行い、配線５ａ、５ｂとなるアルミニウム（ＡＩ
）をＤＣマグネトロンスパッタ法により厚さ約１５００
０Ａ程度で着膜し、フォトリソエツチングで所望のパタ
ーンにバターニングする。これにより、イメージセンサ
の受光素子部分が完成する。Furthermore, a transparent insulating layer 7 made of polyimide or the like is coated and baked, and wirings 5g, 5 are formed from the upper electrode 4 and the guard electrode 6.
In order to form contact via holes 8a and 8b so that the wirings 5a and 5b can be drawn out, patterning is performed in a photolithography process, and aluminum (AI
) to a thickness of approximately 1500 mm by DC magnetron sputtering.
A film is deposited at about 0A and patterned into a desired pattern by photolithography. This completes the light receiving element portion of the image sensor.
上部電極４から導き出された各配線５ａは、例えば駆動
用ＩＣ（図示せず）に接続され、光電変換された電荷を
読み出すようになっている。また、ガード電極６から導
き出された各配線５ｂは、グランド線に接続されている
。共通電極の下部電極２にバイアス電圧を印加し、上部
電極４とカード電極６は同電位となるようにするために
、配線５ａと５ｂの電位は０にしておく。Each wiring 5a led out from the upper electrode 4 is connected to, for example, a driving IC (not shown) to read out photoelectrically converted charges. Further, each wiring 5b led out from the guard electrode 6 is connected to a ground line. In order to apply a bias voltage to the lower electrode 2 of the common electrode and to bring the upper electrode 4 and the card electrode 6 to the same potential, the potentials of the wirings 5a and 5b are set to 0.
本実施例のイメージセンサによれば、イメージセンサの
受光素子を製造する際に光導電層３のａ−３ｉ：Ｈのド
ライエツチング時に光導電層３の側面で起るダメージや
汚染、またレジスト剥離やＩＴＯのウェット処理時に起
る汚染によって光導電層３の側面がリークし易い状態と
なり、この光導電層３側面を経由して流れるリーク電流
が上部電極４の個別電極のまわりに形成したガード電極
６に流れ、更にこのガード電極６から配線５ｂを経由し
て逃がすようにしているので、リーク電流成分と光導電
層３の内部を流れる純粋な電流成分を別々にすることが
でき、光導電層３内部に発生した充電流成分のみを読み
出すことが可能であるため、良好な明暗電流比（Ｓ／Ｎ
比）を得ることができ、イメージセンサの感度を向上さ
せることができる効果がある。According to the image sensor of this embodiment, damage and contamination that occur on the side surface of the photoconductive layer 3 during dry etching of a-3i:H of the photoconductive layer 3 and resist peeling during manufacturing of the light receiving element of the image sensor can be avoided. The side surfaces of the photoconductive layer 3 are susceptible to leakage due to contamination that occurs during the wet processing of ITO and ITO, and the leakage current flowing through the side surfaces of the photoconductive layer 3 is transmitted to the guard electrode formed around the individual electrodes of the upper electrode 4. 6 and further escapes from this guard electrode 6 via the wiring 5b, so that the leakage current component and the pure current component flowing inside the photoconductive layer 3 can be separated, and the photoconductive layer 3. Since it is possible to read only the charging current component generated internally, a good bright-to-dark current ratio (S/N
This has the effect of improving the sensitivity of the image sensor.
また、ガード電極は、上部電極４の個別電極を囲むもの
であればよいので、′Ｍ２図に示すように主走査方向に
対称でない形状であっても構わない。In addition, since the guard electrode only needs to surround the individual electrodes of the upper electrode 4, it may have a shape that is not symmetrical in the main scanning direction as shown in Figure 'M2.
さらに、上部電極４の個別電極からの配線５ａとガード
電極６からの配線５ｂとを多層配線構造とせずに製造の
簡略化のために、第３図に示すように、配線５ａを導く
方向と配線５ｂを導く方向を反対にすることが考えられ
る。Furthermore, in order to simplify manufacturing without forming the wiring 5a from the individual electrodes of the upper electrode 4 and the wiring 5b from the guard electrode 6 into a multilayer wiring structure, as shown in FIG. It is conceivable to reverse the direction in which the wiring 5b is guided.
また、本実施例においては、下部電極２を金属電極とし
、上部電極４を透明電極としたが、ガラス等の基板１の
裏面から光を受光する構成のものであれば、下部電極２
を透明電極とし、上部電極４およびガード電極６をクロ
ム（Ｃ「）等の金属で形成しても同様の効果が得られる
。In addition, in this embodiment, the lower electrode 2 is a metal electrode and the upper electrode 4 is a transparent electrode, but if the structure is such that it receives light from the back surface of the substrate 1 such as glass, the lower electrode
A similar effect can be obtained by using a transparent electrode and forming the upper electrode 4 and the guard electrode 6 from a metal such as chromium (C'').
（発明の効果）
本発明によれば、イメージセンサにおける受光素子の光
導電層を個別化したために、光導電層の側面にて製造工
程上起ったダメージや汚染により光導電層の側面で電流
がリークし易い構造となるが、上部電極を取り囲むよう
に光導電層の上にガード電極を設け、光導電層側面を流
れるリーク電流をこのガード電極から逃がすようにして
いるので、光導電層中を流れる純粋な電流成分と、光導
電層側面を流れるリーク電流を含む電流成分とを分ける
ことができ、光導電層中に発生する光電流のみを読み出
すことができるので、良好な明暗電流比（Ｓ／Ｎ比）を
得ることができ、イメージセンサの感度を向上させるこ
とができる効果がある。(Effects of the Invention) According to the present invention, since the photoconductive layer of the light-receiving element in an image sensor is individualized, current is generated on the side surface of the photoconductive layer due to damage or contamination that occurs during the manufacturing process on the side surface of the photoconductive layer. However, since a guard electrode is provided on the photoconductive layer so as to surround the upper electrode, and the leakage current flowing on the side surface of the photoconductive layer is allowed to escape from this guard electrode, there is no leakage in the photoconductive layer. It is possible to separate the pure current component flowing through the photoconductive layer from the current component containing leakage current flowing through the side surface of the photoconductive layer, and read out only the photocurrent generated in the photoconductive layer, resulting in a good bright/dark current ratio ( This has the effect of improving the sensitivity of the image sensor.
第１図（ａ）は本発明の一実施例に係るイメージセンサ
の受光素子の平面説明図、第１図（ｂ）は第１図（ａ）
のＡ−Ａ’部分の断面説明図、第２図は本発明の別の実
施例の受光素子の平面説明図、第３図は本発明の別の実
施例の受光素子の平面説明図、第４図（ａ）は従来のイ
メージセンサの受光素子の平面説明図、第４図（ｂ）は
第４図（ａ）のＢ−Ｂ’細部分断面説明図である。
１・・・・・・・・・基板
２・・・・・・・・・下部電極
３・・・・・・・・・光導電層
４・・・・・・・・・上部電極
５・・・・・・・・・配線
６・・・・・・・・・ガード電極
７・・・・・・・・・絶縁層
８・・・・・・・・・コンタクト用Ｖ
ａホール
第
図
第２図FIG. 1(a) is an explanatory plan view of a light receiving element of an image sensor according to an embodiment of the present invention, and FIG. 1(b) is a plan view of a light receiving element of an image sensor according to an embodiment of the present invention.
2 is an explanatory plan view of a light receiving element according to another embodiment of the present invention. FIG. 3 is an explanatory plan view of a light receiving element according to another embodiment of the present invention. FIG. 4(a) is a plan explanatory view of a light receiving element of a conventional image sensor, and FIG. 4(b) is a detailed cross-sectional view taken along line BB' of FIG. 4(a). 1... Substrate 2... Lower electrode 3... Photoconductive layer 4... Upper electrode 5. ......Wiring 6...Guard electrode 7...Insulating layer 8...V a hole diagram for contact Figure 2
Claims (1)
部電極上に画素毎に個別化した光導電層と、前記光導電
層上に前記各光導電層に対応する上部電極を順次積層し
た受光素子を有するイメージセンサにおいて、 前記各光導電層の表面より小さい形状にて前記各上部電
極を形成し、前記各上部電極を取り囲むように前記各光
導電層上にガード電極を設けたことを特徴とするイメー
ジセンサ。[Scope of Claims] A lower electrode serving as a common electrode formed on a substrate, a photoconductive layer individualized for each pixel on the lower electrode, and a layer corresponding to each photoconductive layer on the photoconductive layer. In an image sensor having a light receiving element in which upper electrodes are sequentially laminated, each of the upper electrodes is formed in a shape smaller than the surface of each of the photoconductive layers, and a guard is provided on each of the photoconductive layers so as to surround each of the upper electrodes. An image sensor characterized by being provided with electrodes.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2008063A JPH03212975A (en) | 1990-01-17 | 1990-01-17 | Image sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2008063A JPH03212975A (en) | 1990-01-17 | 1990-01-17 | Image sensor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH03212975A true JPH03212975A (en) | 1991-09-18 |
Family
ID=11682888
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2008063A Pending JPH03212975A (en) | 1990-01-17 | 1990-01-17 | Image sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH03212975A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5352921A (en) * | 1991-03-18 | 1994-10-04 | Semiconductor Energy Laboratory Co., Ltd. | Photoelectric conversion device and image sensor |
| JP2001053327A (en) * | 1999-06-11 | 2001-02-23 | Koninkl Philips Electronics Nv | Sensor |
| JP2002118790A (en) * | 2000-08-03 | 2002-04-19 | General Electric Co <Ge> | Solid state imager having gated photodiode and its manufacturing method |
-
1990
- 1990-01-17 JP JP2008063A patent/JPH03212975A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5352921A (en) * | 1991-03-18 | 1994-10-04 | Semiconductor Energy Laboratory Co., Ltd. | Photoelectric conversion device and image sensor |
| JP2001053327A (en) * | 1999-06-11 | 2001-02-23 | Koninkl Philips Electronics Nv | Sensor |
| JP2002118790A (en) * | 2000-08-03 | 2002-04-19 | General Electric Co <Ge> | Solid state imager having gated photodiode and its manufacturing method |
| JP4600964B2 (en) * | 2000-08-03 | 2010-12-22 | ゼネラル・エレクトリック・カンパニイ | Solid-state imager having gated photodiode and method for manufacturing the same |
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