JP2897284B2 - Solid-state imaging device - Google Patents
Solid-state imaging deviceInfo
- Publication number
- JP2897284B2 JP2897284B2 JP1273184A JP27318489A JP2897284B2 JP 2897284 B2 JP2897284 B2 JP 2897284B2 JP 1273184 A JP1273184 A JP 1273184A JP 27318489 A JP27318489 A JP 27318489A JP 2897284 B2 JP2897284 B2 JP 2897284B2
- Authority
- JP
- Japan
- Prior art keywords
- impurity layer
- conductivity type
- type impurity
- imaging device
- solid
- 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.)
- Expired - Fee Related
Links
Landscapes
- Solid State Image Pick-Up Elements (AREA)
- Transforming Light Signals Into Electric Signals (AREA)
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、電荷結合素子
（CCD）を用いたライン型の固体撮像素子に関する。The present invention relates to a solid-state imaging device, and more particularly, to a line-type solid-state imaging device using a charge-coupled device (CCD).
［従来の技術］ CCDラインセンサは、ファクシミリやオートフォーカ
スカメラ等のイメージセンサとして広く利用されてる。[Prior Art] A CCD line sensor is widely used as an image sensor for a facsimile, an autofocus camera, or the like.
第２図は、従来のCCDラインセンサの光電変換部の要
部断面図である。第２図において、３はｎ型シリコン基
板、4aはp-型不純物層、５はn-型不純物層、６は各領域
を分離するp+型チャネルストッパ、７はバリアゲート電
極、８は信号電荷を一時的に蓄積しておくための蓄積ゲ
ート電極であって、n-型不純物層５とその周囲のp-型不
純物層4aが光電変換部１を、また、ゲート電極７、８と
その直下のp-型不純物層4aが電荷蓄積部２を構成してい
る。FIG. 2 is a sectional view of a main part of a photoelectric conversion unit of a conventional CCD line sensor. In FIG. 2, 3 is an n-type silicon substrate, 4a is a p - type impurity layer, 5 is an n - type impurity layer, 6 is a p + type channel stopper for separating each region, 7 is a barrier gate electrode, and 8 is a signal. An n - type impurity layer 5 and a p - type impurity layer 4a around the n - type impurity layer 5 serve as a storage gate electrode for temporarily storing electric charges. The p − -type impurity layer 4 a immediately below constitutes the charge storage section 2.
動作について説明すると、n-型不純物層５内およびそ
の周囲の空乏層内に入射した光は、ここで光電変換され
て信号電荷となりバリアゲート電極７を介して蓄積ゲー
ト電極８下に一時的に蓄積される。その後この電荷はト
ランスファゲート電極を介して図の右側に存在するCCD
の転送領域内に送り込まれ、しかる後この転送領域内を
紙面に対して垂直方向に転送される。The operation will be described. The light incident on the n − -type impurity layer 5 and the depletion layer around it is photoelectrically converted into signal charges and temporarily goes below the storage gate electrode 8 via the barrier gate electrode 7. Stored. This charge is then transferred to the CCD on the right side of the figure via the transfer gate electrode.
Is transferred into the transfer area, and then transferred in the transfer area in a direction perpendicular to the paper surface.
［発明が解決しようとする課題］ 上述した従来の構造では、入射光を光電変換するp-型
不純物層4aを半導体基板の表面から浅いところに形成し
ているので、入射光がこの不純物層より深い位置に到達
した場合には、その光電変換電荷を信号電荷として捕捉
できないという欠点がある。そのため、感度が低下し、
就中、分光感度特性が劣化した。[Problem to be Solved by the Invention] In the conventional structure described above, the p - type impurity layer 4a for photoelectrically converting incident light is formed at a position shallow from the surface of the semiconductor substrate. When it reaches a deep position, there is a disadvantage that the photoelectric conversion charge cannot be captured as a signal charge. Therefore, the sensitivity decreases,
Above all, the spectral sensitivity characteristics deteriorated.
而して、このp-型不純物層4aは、電荷転送部や電荷蓄
積部の領域としても用いられるものであるため、転送速
度の低下をもたらさないように低濃度の領域となされて
きた。そして、不純物濃度の低い場合には、その層を深
く形成することが不純物濃度や深さの制御性の面で困難
であることから、p-型不純物層4aには浅い層が用いられ
てきた。Since the p − -type impurity layer 4a is also used as a region for the charge transfer portion and the charge storage portion, it has been formed as a low-concentration region so as not to lower the transfer speed. When the impurity concentration is low, it is difficult to form the layer deeply in terms of the controllability of the impurity concentration and the depth, and therefore, a shallow layer has been used for the p − -type impurity layer 4a. .
［課題を解決するための手段］ 本発明による固体撮像素子は、半導体基板内に存在す
る前記半導体基板と逆導電型の不純物層の表面領域内に
光電変換領域が設けられ、前記逆導電型の不純物層上に
は絶縁膜を介して蓄積ゲート電極および転送ゲート電極
が形成されたものであって、前記不純物層は前記光電変
換領域の直下で電荷蓄積部および電荷転送部直下に比べ
不純物濃度が高くかつ深く形成されている。[Means for Solving the Problems] In a solid-state imaging device according to the present invention, a photoelectric conversion region is provided in a surface region of an impurity layer of a conductivity type opposite to that of the semiconductor substrate present in a semiconductor substrate, and the opposite conductivity type is provided. A storage gate electrode and a transfer gate electrode are formed on the impurity layer via an insulating film, and the impurity layer has an impurity concentration immediately below the photoelectric conversion region and lower than that immediately below the charge accumulation portion and the charge transfer portion. It is formed high and deep.
［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要部断面図である。第
１図において、第２図の従来例と同一の部分には同一の
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、本実施例では、光電変換領域であるn-型不純物層５
の直下ではｐ型不純物層９が深く形成されているが、そ
れ以外の領域ではp-型不純物層４が一様な浅い領域に形
成されている。ここに、ｐ型不純物層９はドーズ量2.4
×1012cm-2のボロンイオンの注入により深さ９μｍに形
成された領域であり、またp-型不純物層は４はドーズ量
1.2×1012cm-2のボロンイオンの注入により深さ６μｍ
に形成された領域である。ここに、p-型不純物層４の濃
度は電荷転送動作を劣化させない為にｐ型不純物層９の
濃度に比べ低くなされている。FIG. 1 is a sectional view of a main part of an embodiment of the present invention. In FIG. 1, the same parts as those in the conventional example of FIG. 2 are denoted by the same reference numerals, and thus duplicate description will be omitted. However, in the present embodiment, the n − -type impurity layer which is a photoelectric conversion region is used. 5
, The p-type impurity layer 9 is formed deep, but in other regions, the p − -type impurity layer 4 is formed in a uniform shallow region. Here, the p-type impurity layer 9 has a dose of 2.4.
This is a region formed to a depth of 9 μm by implantation of boron ions of × 10 12 cm −2 , and the p - type impurity layer has a dose of 4
6 μm depth by implantation of boron ions of 1.2 × 10 12 cm -2
Area formed in Here, the concentration of the p − -type impurity layer 4 is lower than the concentration of the p-type impurity layer 9 so as not to deteriorate the charge transfer operation.
動作は第２図の従来例のそれと同様であるが、本実施
例のものは、半導体基板内の深いところで光電変換され
た信号電荷をもn-型不純物層５に集積することができる
ので、従来例と比較して感度特性が向上している。The operation is the same as that of the conventional example of FIG. 2, but in the present example, the signal charges photoelectrically converted at a deep position in the semiconductor substrate can also be integrated in the n − -type impurity layer 5. The sensitivity characteristics are improved as compared with the conventional example.
［発明の効果］ 以上説明したように、本発明は、光電変換部直下部分
のみｐ型不純物層を基板内深くまで形成したものである
ので、本発明によれば、電荷転送部の特性を犠牲にする
ことなく、基板内深くで光電変換される入射光について
も信号電荷として取り出すことができる。従って、本発
明によれば、感度を向上させ、分光感度特性を改善する
ことができる。[Effects of the Invention] As described above, according to the present invention, only the portion immediately below the photoelectric conversion portion has the p-type impurity layer formed deep inside the substrate. Therefore, according to the present invention, the characteristics of the charge transfer portion are sacrificed. Without incident light, incident light that is photoelectrically converted deep within the substrate can also be extracted as signal charges. Therefore, according to the present invention, the sensitivity can be improved and the spectral sensitivity characteristics can be improved.
第１図は、本発明の一実施例を示す断面図、第２図は、
従来例を示す断面図である。 １……光電変換部、２……電荷蓄積部、３……ｎ型シリ
コン基板、４、4a……p-型不純物層、５……n-型不純物
層、６……p+型チャネルストッパ、７……バリアゲート
電極、８……蓄積ゲート電極、９……ｐ型不純物層。FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG.
It is sectional drawing which shows a prior art example. DESCRIPTION OF SYMBOLS 1 ... Photoelectric conversion part, 2 ... Charge accumulation part, 3 ... N-type silicon substrate, 4, 4a ... P - type impurity layer, 5 ... N - type impurity layer, 6 ... P + type channel stopper , 7 ... barrier gate electrode, 8 ... storage gate electrode, 9 ... p-type impurity layer.
Claims (1)
２導電型半導体層の表面領域内に第１導電型の光電変換
領域が設けられ、前記第２導電型半導体層上には絶縁膜
を介して蓄積ゲート電極および転送ゲート電極が形成さ
れている固体撮像素子において、前記第２導電型半導体
層は前記光電変換領域の直下において他の部分より深く
かつ他の部分より不純物濃度が高くなされていることを
特徴とする固体撮像素子。1. A first conductivity type photoelectric conversion region is provided in a surface region of a second conductivity type semiconductor layer formed on a first conductivity type semiconductor substrate, and a second conductivity type semiconductor layer is provided on the second conductivity type semiconductor layer. In a solid-state imaging device in which a storage gate electrode and a transfer gate electrode are formed via an insulating film, the second conductivity type semiconductor layer is deeper than other portions and has an impurity concentration lower than other portions immediately below the photoelectric conversion region. A solid-state imaging device characterized by being made high.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1273184A JP2897284B2 (en) | 1989-10-20 | 1989-10-20 | Solid-state imaging device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1273184A JP2897284B2 (en) | 1989-10-20 | 1989-10-20 | Solid-state imaging device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03135068A JPH03135068A (en) | 1991-06-10 |
| JP2897284B2 true JP2897284B2 (en) | 1999-05-31 |
Family
ID=17524272
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1273184A Expired - Fee Related JP2897284B2 (en) | 1989-10-20 | 1989-10-20 | Solid-state imaging device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2897284B2 (en) |
-
1989
- 1989-10-20 JP JP1273184A patent/JP2897284B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH03135068A (en) | 1991-06-10 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |