JPH02218162A - Solid-state image sensing element - Google Patents
Solid-state image sensing elementInfo
- Publication number
- JPH02218162A JPH02218162A JP1039661A JP3966189A JPH02218162A JP H02218162 A JPH02218162 A JP H02218162A JP 1039661 A JP1039661 A JP 1039661A JP 3966189 A JP3966189 A JP 3966189A JP H02218162 A JPH02218162 A JP H02218162A
- Authority
- JP
- Japan
- Prior art keywords
- photoelectric conversion
- transparent electrode
- conversion element
- solid
- electrons
- 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
- 238000006243 chemical reaction Methods 0.000 claims abstract description 27
- 239000004065 semiconductor Substances 0.000 claims abstract description 8
- 238000003384 imaging method Methods 0.000 claims description 2
- 230000005527 interface trap Effects 0.000 abstract description 4
- 239000011229 interlayer Substances 0.000 abstract description 4
- 239000010410 layer Substances 0.000 abstract description 2
- 239000000758 substrate Substances 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 2
- 239000004020 conductor Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- RHZWSUVWRRXEJF-UHFFFAOYSA-N indium tin Chemical compound [In].[Sn] RHZWSUVWRRXEJF-UHFFFAOYSA-N 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
Landscapes
- Solid State Image Pick-Up Elements (AREA)
Abstract
Description
【発明の詳細な説明】
［産業上の利用分野］
本発明は、固体撮像素子に関し、特に、光電変換素子領
域における暗電流の発生を低減せしめた固体撮像素子に
関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a solid-state image sensor, and particularly to a solid-state image sensor in which dark current generation in a photoelectric conversion element region is reduced.
〔従来の技術］ 従来の固体撮像素子の断面図を第４図に示す。[Conventional technology] FIG. 4 shows a cross-sectional view of a conventional solid-state image sensor.
同図に示されるように、Ｎ型半導体サブストレート１０
上には、Ｐウェル１１が形成され、該ウェル内には、光
電変換素子領域１２、チャネル領域１４が設けられ、ま
た、これらの領域を囲んでチャネルストッパ１５が設け
られている。Ｐウェル１１上には、ゲート酸化膜１６と
フィールド酸化膜１７とが形成されており、その上には
電荷転送電極１８が設けられている。さらに、全体は層
間絶縁膜で被覆され、その上には光電変換素子領域１２
上に開口を有する遮光膜２１が形成されている。As shown in the figure, an N-type semiconductor substrate 10
A P well 11 is formed above, a photoelectric conversion element region 12 and a channel region 14 are provided within the well, and a channel stopper 15 is provided surrounding these regions. A gate oxide film 16 and a field oxide film 17 are formed on the P-well 11, and a charge transfer electrode 18 is provided thereon. Further, the entire surface is covered with an interlayer insulating film, and a photoelectric conversion element region 12 is provided on the interlayer insulating film.
A light shielding film 21 having an opening thereon is formed.
この撮像素子において、所定の時間光電変換素子領域１
３に蓄積された光電変換電荷は、電荷転送電極１８に読
み出しパルスを印加することにより、読み出し領域１３
を介してチャネル領域１４へ読み出され、この領域内を
紙面に垂直方向に転送される。In this image sensor, the photoelectric conversion element area 1
The photoelectric conversion charges accumulated in the readout area 13 are transferred to the readout area 13 by applying a readout pulse to the charge transfer electrode 18.
The signal is read out to the channel region 14 through the channel region 14, and is transferred within this region in a direction perpendicular to the plane of the paper.
［発明が解決しようとする問題点コ
上述した従来の固体撮像素子の光電変換素子領域におけ
るバンド状態図を第５図に示す、同図から明らかなよう
に、従来素子にあっては、光電変換電荷（この例の場合
は電子）は基板表面に集められる。而して、光電変換素
子領域表面と酸化膜との界面には界面トラップが存在し
、また、光電変換素子領域の表面付近には欠陥等による
トラップレベルが存在するので、表面近くでは信号電荷
ではない電荷が熱的に励起しやすい、ところが、従来の
素子構造にあっては、この電荷は基板表面において信号
電荷に加算されるので、これが暗電流となって画質を劣
化させる。[Problems to be Solved by the Invention] FIG. 5 shows a band state diagram in the photoelectric conversion element region of the conventional solid-state image sensor described above. Charge (electrons in this example) is collected on the substrate surface. Therefore, there are interface traps at the interface between the surface of the photoelectric conversion element region and the oxide film, and there is also a trap level near the surface of the photoelectric conversion element region due to defects, etc. However, in conventional device structures, this charge is added to the signal charge on the substrate surface, resulting in a dark current that deteriorates image quality.
［問題点を解決するための手段］
本発明による固体撮像素子は、第１導電型半導体領域内
に形成された第２導電型の光電変換素子領域と、前記第
１導電型半導体領域内に形成された第２導電型のチャネ
ル領域とを具備するものであって、前記光電変換素子領
域上には該光電変換素子領域内部に電位井戸を形成する
ための透明電極が絶縁膜を介して形成されている。[Means for Solving the Problems] A solid-state imaging device according to the present invention includes a photoelectric conversion element region of a second conductivity type formed within a semiconductor region of a first conductivity type, and a photoelectric conversion element region formed within a semiconductor region of a first conductivity type. a channel region of a second conductivity type, and a transparent electrode for forming a potential well inside the photoelectric conversion element region is formed on the photoelectric conversion element region via an insulating film. ing.
［実施例］
次に、本発明の実施例について、図面を参照して説明す
る。[Example] Next, an example of the present invention will be described with reference to the drawings.
第１図は、本発明の一実施例の断面図である。FIG. 1 is a sectional view of one embodiment of the present invention.
同図において、第４図に示した従来例と同一の部分につ
いては同一の参照番号が付されているので重複した説明
は省略するが、この実施例においては、眉間絶縁膜１９
上には全面にＩ Ｔ Ｏ（ｉｎｄｉｕｍｔｉｎ ｏｘｉ
ｄｅ）からなる透明電極２０が形成されている。この透
明電極に負の電圧を印加して、光電変換素子領域１３の
表面に反転層が形成されるようにする。このときのバン
ド状態図を第２図に示す、この状態では、光電変換電荷
（′ｇ１子）は、光電変換素子領域１３内の電位の最も
深いところに集められる。一方、表面付近でトラップレ
ベルを経由して熱的に励起した電子は、その部分が反転
状態にあるので直ちに正孔と再結合してしまい、信号電
荷に加算されることは殆どない、さらに、半導体と酸化
膜との界面の電位が透明電極２０によって一定に保たれ
ているので、界面トラップによる電荷の発生自体も減少
する。In this figure, parts that are the same as those in the conventional example shown in FIG.
ITO (indium tin oxidation) is applied on the entire surface.
A transparent electrode 20 made of de) is formed. A negative voltage is applied to this transparent electrode so that an inversion layer is formed on the surface of the photoelectric conversion element region 13. A band state diagram at this time is shown in FIG. 2. In this state, the photoelectric conversion charge ('g1 child) is collected at the deepest potential within the photoelectric conversion element region 13. On the other hand, electrons that are thermally excited via the trap level near the surface immediately recombine with holes because that part is in an inverted state, and are hardly added to the signal charge. Since the potential at the interface between the semiconductor and the oxide film is kept constant by the transparent electrode 20, the generation of charges due to interface traps is also reduced.
次に、第３図を参照して、本発明の他の実施例について
説明する。この実施例では、先の実施例で透明電極を全
面に形成していたが、本実施例では、光電変換素子領域
列毎に透明電極２０ａが設けられている。この実施例で
も、透明電ｆｉ２０ ａに負の電圧が印加されて第２図
と同様のバンド状態になされ、先の実施例と同様の効果
を奏することができる。Next, another embodiment of the present invention will be described with reference to FIG. In this embodiment, the transparent electrode was formed over the entire surface in the previous embodiment, but in this embodiment, a transparent electrode 20a is provided for each row of photoelectric conversion element regions. In this embodiment as well, a negative voltage is applied to the transparent electrode fi 20a to create a band state similar to that shown in FIG. 2, and the same effects as in the previous embodiment can be achieved.
なお、透明電極は、ＩＴＯの外に、Ｉｎ２Ｏ３，５ｎ０
２など、他の透明導電材料を用いて形成してもよい。In addition to ITO, the transparent electrode is made of In2O3,5n0
It may be formed using other transparent conductive materials such as No. 2.
［発明の効果］
以上説明したように、本発明は、光電変換素子領域上に
絶縁膜を介、して透明電極を設け、該電極に光電変換素
子内部に電位井戸が形成されるように電圧を印加するも
のであるので、本発明によれば、界面トラップによる電
荷の発生を抑制することができ、また、基板表面付近で
熱的に発生する電荷を速やかに再結合せしめることがで
きる。したがって、本発明によれば、固体撮像素子の暗
電流を格段に低減せしめることができる。[Effects of the Invention] As explained above, the present invention provides a transparent electrode on a photoelectric conversion element region with an insulating film interposed therebetween, and applies a voltage to the electrode so that a potential well is formed inside the photoelectric conversion element. Therefore, according to the present invention, generation of charges due to interface traps can be suppressed, and charges thermally generated near the substrate surface can be quickly recombined. Therefore, according to the present invention, the dark current of the solid-state image sensor can be significantly reduced.
第１図は、本発明の一実施例を示す断面図、第２図は、
第１図の固体撮像素子のバンド状態図、第３図は、本発
明の他の実施例を示す断面図、第４図は、従来例の断面
図、第５図は、第４図の固体撮像素子のバンド状態図で
ある。
１０・・・Ｎ型半導体サブストレート、 １１・・・
Ｐウェル、 １２・・・光電変換素子領域、 １３・・
・読み出し部、 １４・・・チャネル領域、 １５・・
・チャネルストッパ、 １６・・・ゲート酸化膜、
１７・・・フィールド酸化膜、 １８・・・電荷転送電
極、 １９・・・層間絶縁膜、 ２０．２０ａ・・・透
明電極、２１・・・遮光膜。FIG. 1 is a sectional view showing one embodiment of the present invention, and FIG. 2 is a sectional view showing an embodiment of the present invention.
FIG. 1 is a band state diagram of the solid-state image sensor, FIG. 3 is a cross-sectional view showing another embodiment of the present invention, FIG. 4 is a cross-sectional view of a conventional example, and FIG. 5 is a solid-state image sensor shown in FIG. FIG. 3 is a band state diagram of an image sensor. 10... N-type semiconductor substrate, 11...
P well, 12... photoelectric conversion element region, 13...
・Reading unit, 14...channel region, 15...
・Channel stopper, 16... gate oxide film,
17... Field oxide film, 18... Charge transfer electrode, 19... Interlayer insulating film, 20.20a... Transparent electrode, 21... Light shielding film.
Claims (1)
変換素子領域と、前記第１導電型半導体領域内に形成さ
れた第２導電型のチャネル領域とを具備する固体撮像素
子において、前記光電変換素子領域上には該光電変換素
子領域内部に電位井戸を形成するための透明電極が絶縁
膜を介して形成されていることを特徴とする固体撮像素
子。A solid-state imaging device comprising a second conductivity type photoelectric conversion element region formed within a first conductivity type semiconductor region, and a second conductivity type channel region formed within the first conductivity type semiconductor region, A solid-state image sensing device characterized in that a transparent electrode for forming a potential well inside the photoelectric conversion element region is formed on the photoelectric conversion element region with an insulating film interposed therebetween.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1039661A JPH02218162A (en) | 1989-02-20 | 1989-02-20 | Solid-state image sensing element |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1039661A JPH02218162A (en) | 1989-02-20 | 1989-02-20 | Solid-state image sensing element |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH02218162A true JPH02218162A (en) | 1990-08-30 |
Family
ID=12559269
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1039661A Pending JPH02218162A (en) | 1989-02-20 | 1989-02-20 | Solid-state image sensing element |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH02218162A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5424574A (en) * | 1992-09-23 | 1995-06-13 | Scientific Imaging Technologies, Inc. | Light shield for a back-side thinned CCD |
| JPH11121729A (en) * | 1997-08-20 | 1999-04-30 | Internatl Business Mach Corp <Ibm> | Band gap designed active pickcell cell |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6065565A (en) * | 1983-09-20 | 1985-04-15 | Toshiba Corp | Solid-state image sensor |
| JPS60214172A (en) * | 1984-04-09 | 1985-10-26 | Toshiba Corp | Solid-state image pickup device |
| JPS61229355A (en) * | 1985-04-03 | 1986-10-13 | Matsushita Electric Ind Co Ltd | Solid-state image pickup device |
-
1989
- 1989-02-20 JP JP1039661A patent/JPH02218162A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6065565A (en) * | 1983-09-20 | 1985-04-15 | Toshiba Corp | Solid-state image sensor |
| JPS60214172A (en) * | 1984-04-09 | 1985-10-26 | Toshiba Corp | Solid-state image pickup device |
| JPS61229355A (en) * | 1985-04-03 | 1986-10-13 | Matsushita Electric Ind Co Ltd | Solid-state image pickup device |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5424574A (en) * | 1992-09-23 | 1995-06-13 | Scientific Imaging Technologies, Inc. | Light shield for a back-side thinned CCD |
| JPH11121729A (en) * | 1997-08-20 | 1999-04-30 | Internatl Business Mach Corp <Ibm> | Band gap designed active pickcell cell |
| US6278102B1 (en) | 1997-08-20 | 2001-08-21 | International Business Machines Corporation | Method of detecting electromagnetic radiation with bandgap engineered active pixel cell design |
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