JPH0661470A - Solid-state image sensing device and its manufacture - Google Patents
Solid-state image sensing device and its manufactureInfo
- Publication number
- JPH0661470A JPH0661470A JP4235324A JP23532492A JPH0661470A JP H0661470 A JPH0661470 A JP H0661470A JP 4235324 A JP4235324 A JP 4235324A JP 23532492 A JP23532492 A JP 23532492A JP H0661470 A JPH0661470 A JP H0661470A
- Authority
- JP
- Japan
- Prior art keywords
- film
- silicon
- silicon oxide
- gate insulating
- oxide film
- 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
Landscapes
- Solid State Image Pick-Up Elements (AREA)
- Transforming Light Signals Into Electric Signals (AREA)
- Formation Of Insulating Films (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、電荷転送部にゲート絶
縁膜を有する固体撮像装置及びその製造方法に関するも
のである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state image pickup device having a gate insulating film in a charge transfer section and a manufacturing method thereof.
【０００２】[0002]
【従来の技術】ＣＣＤ等の固体撮像装置では、隣接する
ＭＯＳキャパシタのポテンシャル井戸を順次に結合させ
て信号電荷を転送するので、電荷転送部にＭＯＳキャパ
シタのゲート絶縁膜を有している。このゲート絶縁膜と
しては、ＳｉＯ2 膜のみの単層膜の他に、ＳｉＯ2 膜と
Ｓｉ3 Ｎ4 膜とＳｉＯ2 膜とが順次に積層されておりＯ
ＮＯ膜と称されている３層膜が用いられている。2. Description of the Related Art In a solid-state image pickup device such as a CCD, since the potential wells of adjacent MOS capacitors are sequentially coupled to transfer signal charges, the charge transfer portion has a gate insulating film of the MOS capacitors. As the gate insulating film, in addition to the single layer film of only SiO 2 film and the SiO 2 film and the Si 3 N 4 film and the SiO 2 film are sequentially stacked O
A three-layer film called an NO film is used.
【０００３】特に、ＯＮＯ膜では、３層膜でありピンホ
ールが殆どないので耐圧歩留りが高く、金属等の拡散を
Ｓｉ3 Ｎ4 膜で阻止することができるので汚染が少ない
という利点がある。また、半導体基板上に最初に形成し
たＯＮＯ膜を第２層目の導電膜で形成するゲート電極の
ゲート絶縁膜としても用い、ゲート絶縁膜を一旦除去し
てから再び形成しなくてもよいので、最初に形成したゲ
ート絶縁膜に比べてその後に形成したゲート絶縁膜が半
導体基板内へ陥没することがなく、半導体基板内の転送
部が平坦になって転送を良好に行うことができるという
利点もある。In particular, the ONO film is a three-layer film and has almost no pinholes, so that the withstand voltage yield is high and the diffusion of metal or the like can be prevented by the Si 3 N 4 film, so that there is an advantage that there is little contamination. Further, since the ONO film formed first on the semiconductor substrate is also used as the gate insulating film of the gate electrode formed of the second conductive film, the gate insulating film does not have to be removed and then formed again. As compared with the gate insulating film formed first, the gate insulating film formed after that does not sink into the semiconductor substrate, and the transfer portion in the semiconductor substrate is flat and the transfer can be performed favorably. There is also.
【０００４】[0004]
【発明が解決しようとする課題】しかし、ＯＮＯ膜で
も、シリコン基板との界面の構造はＳｉＯ2 ／Ｓｉであ
り、界面特性が良好とは言い難い。即ち、この界面には
通常は１０10〜１０12ｃｍ-2ｅＶ-1の密度の表面準位が
存在しており、この表面準位を介して熱的に発生する電
荷によって暗電流が観測されるが、ＳｉＯ2 ／Ｓｉの界
面構造では温度の変動による表面準位密度の変動が大き
い。However, even in the ONO film, the structure of the interface with the silicon substrate is SiO 2 / Si, and it is difficult to say that the interface characteristics are good. That is, there is usually a surface level having a density of 10 10 to 10 12 cm -2 eV -1 at this interface, and a dark current is observed by the charges thermally generated through this surface level. However, in the SiO 2 / Si interface structure, the surface state density fluctuates greatly due to temperature fluctuations.
【０００５】この様な表面準位密度は、転送用のゲート
電極に静電的に高電圧が印加された場合（サージ）や、
通常の動作条件でも長時間に亙ってゲート電極に電圧が
印加された場合や、固体撮像装置に放射線が照射された
場合に、特に増大する。そして、温度の上昇等によって
表面準位密度が増大して、暗電流が増加すると、転送可
能な信号電荷量が少なくなるのみならず、暗電流自体の
変動によるノイズが多くなって、撮像特性が低下する。Such a surface level density is generated when a high voltage is electrostatically applied to the transfer gate electrode (surge),
Even under normal operating conditions, it increases particularly when a voltage is applied to the gate electrode for a long time or when the solid-state imaging device is irradiated with radiation. When the surface level density increases due to temperature rise and the like, and the dark current increases, not only the amount of signal charge that can be transferred decreases, but also the noise due to the fluctuation of the dark current itself increases and the imaging characteristics are improved. descend.
【０００６】[0006]
【課題を解決するための手段】請求項１の固体撮像装置
では、シリコン酸窒化膜１５上にシリコン窒化膜１６と
シリコン酸化膜１７とが順次に積層されて成る３層膜が
電荷転送部のゲート絶縁膜１８になっている。In the solid-state image pickup device according to the first aspect of the present invention, a three-layer film formed by sequentially stacking a silicon nitride film 16 and a silicon oxide film 17 on a silicon oxynitride film 15 is a charge transfer portion. It is the gate insulating film 18.
【０００７】請求項２の固体撮像装置の製造方法では、
シリコン基板１１の表面を酸化して第１のシリコン酸化
膜を形成し、窒素を含む雰囲気中で前記第１のシリコン
酸化膜を熱処理してこの第１のシリコン酸化膜をシリコ
ン酸窒化膜１５にし、前記シリコン酸窒化膜１５上にシ
リコン窒化膜１６を堆積させ、前記シリコン窒化膜１６
の表面を酸化してこのシリコン窒化膜１６上に第２のシ
リコン酸化膜１７を形成し、前記シリコン酸窒化膜１５
上に前記シリコン窒化膜１６と前記第２のシリコン酸化
膜１７とが順次に積層されて成る３層膜を電荷転送部の
ゲート絶縁膜１８にする。In the method of manufacturing a solid-state image pickup device according to claim 2,
The surface of the silicon substrate 11 is oxidized to form a first silicon oxide film, and the first silicon oxide film is heat treated in an atmosphere containing nitrogen to form the first silicon oxide film as a silicon oxynitride film 15. A silicon nitride film 16 is deposited on the silicon oxynitride film 15,
The surface of the silicon oxynitride film 15 is oxidized to form a second silicon oxide film 17 on the silicon nitride film 16.
A three-layer film formed by sequentially stacking the silicon nitride film 16 and the second silicon oxide film 17 thereon is used as the gate insulating film 18 of the charge transfer portion.
【０００８】[0008]
【作用】本発明による固体撮像装置及びその製造方法で
は、電荷転送部のゲート絶縁膜１８のうちで基板１１と
の界面を構成している部分がシリコン酸窒化膜１５であ
り、シリコン酸化膜のみの単層膜やシリコン酸化膜上に
シリコン窒化膜とシリコン酸化膜とが順次に積層されて
成る３層膜等の様にシリコン酸化膜で界面を構成してい
る場合に比べて、界面特性が良好で、表面準位密度の変
動が少ない。In the solid-state image pickup device and the method of manufacturing the same according to the present invention, the portion of the gate insulating film 18 of the charge transfer portion which constitutes the interface with the substrate 11 is the silicon oxynitride film 15, and only the silicon oxide film is formed. In comparison with the case where the interface is composed of a silicon oxide film such as a single layer film or a three-layer film in which a silicon nitride film and a silicon oxide film are sequentially laminated on a silicon oxide film, the interface characteristics are Good and little fluctuation of surface state density.
【０００９】[0009]
【実施例】以下、ＣＣＤに適用した本発明の一実施例
を、図１を参照しながら説明する。本実施例では、図１
に示す様に、シリコン基板１１中に、感光画素部のフォ
トダイオードを構成するＮ型の拡散層１２と、電荷転送
部のチャネルになるＮ型の拡散層１３と、チャネルスト
ッパになるＰ+ 型の拡散層１４とを、従来公知の工程で
形成する。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention applied to a CCD will be described below with reference to FIG. In this embodiment, FIG.
As shown in FIG. 3, in the silicon substrate 11, an N type diffusion layer 12 that constitutes a photodiode of a photosensitive pixel portion, an N type diffusion layer 13 that serves as a channel of a charge transfer portion, and a P + type that serves as a channel stopper. And the diffusion layer 14 are formed by a conventionally known process.
【００１０】次に、シリコン基板１１をドライ酸化また
はウエット酸化して、シリコン基板１１の表面にシリコ
ン酸化膜をまず形成し、更にこのシリコン酸化膜をＮＨ
3 雰囲気中でアニールする。アニールの最適条件は、シ
リコン酸化膜の膜厚にも依存するが、温度が９００〜１
０００℃で時間が１０分〜１時間程度である。このアニ
ールによって、シリコン酸化膜の表面、及びシリコン酸
化膜とシリコン基板１１との界面付近にＮ原子が偏析
し、シリコン酸化膜がシリコン酸窒化膜１５になる。Next, the silicon substrate 11 is dry-oxidized or wet-oxidized to first form a silicon oxide film on the surface of the silicon substrate 11, and this silicon oxide film is further subjected to NH3.
3 Anneal in an atmosphere. The optimum annealing condition depends on the film thickness of the silicon oxide film, but the temperature is 900 to 1
The time is about 10 minutes to 1 hour at 000 ° C. By this annealing, N atoms are segregated on the surface of the silicon oxide film and near the interface between the silicon oxide film and the silicon substrate 11, and the silicon oxide film becomes the silicon oxynitride film 15.
【００１１】次に、ＳｉＨ2 Ｃｌ2 ガスとＮＨ3 ガスと
を原料ガスとする通常のＣＶＤ法で、シリコン酸窒化膜
１５上にシリコン窒化膜１６を堆積させ、更にシリコン
窒化膜１６の表面をウエット酸化して、シリコン窒化膜
１６上にシリコン酸化膜１７を形成する。本実施例で
は、以上の様にして形成したシリコン酸窒化膜１５とシ
リコン窒化膜１６とシリコン酸化膜１７との３層膜を、
ゲート絶縁膜１８にする。Then, a silicon nitride film 16 is deposited on the silicon oxynitride film 15 by a normal CVD method using SiH 2 Cl 2 gas and NH 3 gas as source gases, and the surface of the silicon nitride film 16 is further deposited. Wet oxidation is performed to form a silicon oxide film 17 on the silicon nitride film 16. In this embodiment, the three-layer film including the silicon oxynitride film 15, the silicon nitride film 16, and the silicon oxide film 17 formed as described above is
The gate insulating film 18 is used.
【００１２】その後は、従来公知の工程を実行する。即
ち、まずゲート絶縁膜１８上で多結晶シリコン膜をパタ
ーニングして、転送用のゲート電極２１を形成する。そ
して、絶縁膜としてのＰＳＧ膜２２を全面に堆積させ、
感光画素部上で開口２３ａを有する遮光用マスクとして
のＡｌ膜２３をＰＳＧ膜２２上でパターニングする。そ
して更に、保護絶縁膜２４を全面に形成して、本実施例
のＣＣＤを完成させる。After that, a conventionally known process is executed. That is, first, the polycrystalline silicon film is patterned on the gate insulating film 18 to form the transfer gate electrode 21. Then, a PSG film 22 as an insulating film is deposited on the entire surface,
An Al film 23 as a light-shielding mask having an opening 23a on the photosensitive pixel portion is patterned on the PSG film 22. Then, a protective insulating film 24 is formed on the entire surface to complete the CCD of this embodiment.
【００１３】以上の様な実施例では、ゲート絶縁膜１８
とシリコン基板１１との界面特性が、ＯＮＯ膜等とシリ
コン基板１１との界面特性に比べて優れており、表面準
位密度の変動が少ない。このため、同一の電気的ストレ
スを与えても、ＯＮＯ膜をゲート絶縁膜として用いた場
合に比べて、暗電流の増加が１／５〜１／１０に低減し
ている。In the above embodiment, the gate insulating film 18
The interface characteristic between the silicon substrate 11 and the silicon substrate 11 is superior to the interface characteristic between the ONO film and the silicon substrate 11, and the fluctuation of the surface state density is small. Therefore, even if the same electric stress is applied, the increase in dark current is reduced to 1/5 to 1/10 of that in the case where the ONO film is used as the gate insulating film.
【００１４】この様に本実施例でゲート絶縁膜１８とシ
リコン基板１１との界面特性が優れているのは、シリコ
ン基板１１との界面付近におけるシリコン酸窒化膜１５
中のＮ原子またはその結合によるものと考えられる。な
お、シリコン酸窒化膜１５を形成するためのＮＨ3 雰囲
気中でのアニール後に、更に酸素雰囲気中でアニールを
行えば、界面特性が更に向上する。As described above, the excellent interface characteristic between the gate insulating film 18 and the silicon substrate 11 in this embodiment is that the silicon oxynitride film 15 near the interface with the silicon substrate 11 is excellent.
It is thought to be due to the N atom in the inside or its bond. If annealing is further performed in an oxygen atmosphere after annealing in an NH 3 atmosphere for forming the silicon oxynitride film 15, the interface characteristics are further improved.
【００１５】[0015]
【発明の効果】本発明による固体撮像装置及びその製造
方法では、電荷転送部のゲート絶縁膜と基板との界面に
おける表面準位密度の変動が少ないので、暗電流の増加
を抑制することができる。このため、転送可能な信号電
荷量が多く且つ暗電流の変動によるノイズが少なくて、
優れた撮像特性を得ることができる。In the solid-state image pickup device and the method for manufacturing the same according to the present invention, since the fluctuation of the surface level density at the interface between the gate insulating film of the charge transfer portion and the substrate is small, it is possible to suppress the increase of dark current. . Therefore, the amount of signal charges that can be transferred is large, and the noise due to changes in dark current is small,
Excellent imaging characteristics can be obtained.
【図１】本発明の一実施例の側断面図である。FIG. 1 is a side sectional view of an embodiment of the present invention.
１１ シリコン基板 １５ シリコン酸窒化膜 １６ シリコン窒化膜 １７ シリコン酸化膜 １８ ゲート絶縁膜 11 silicon substrate 15 silicon oxynitride film 16 silicon nitride film 17 silicon oxide film 18 gate insulating film
Claims (2)
シリコン酸化膜とが順次に積層されて成る３層膜が電荷
転送部のゲート絶縁膜になっている固体撮像装置。1. A solid-state imaging device in which a three-layer film formed by sequentially stacking a silicon nitride film and a silicon oxide film on a silicon oxynitride film serves as a gate insulating film of a charge transfer portion.
リコン酸化膜を形成し、 窒素を含む雰囲気中で前記第１のシリコン酸化膜を熱処
理してこの第１のシリコン酸化膜をシリコン酸窒化膜に
し、 前記シリコン酸窒化膜上にシリコン窒化膜を堆積させ、 前記シリコン窒化膜の表面を酸化してこのシリコン窒化
膜上に第２のシリコン酸化膜を形成し、 前記シリコン酸窒化膜上に前記シリコン窒化膜と前記第
２のシリコン酸化膜とが順次に積層されて成る３層膜を
電荷転送部のゲート絶縁膜にする固体撮像装置の製造方
法。2. A surface of a silicon substrate is oxidized to form a first silicon oxide film, and the first silicon oxide film is heat-treated in an atmosphere containing nitrogen to convert the first silicon oxide film into silicon oxide. Forming a nitride film, depositing a silicon nitride film on the silicon oxynitride film, oxidizing the surface of the silicon nitride film to form a second silicon oxide film on the silicon nitride film, A method of manufacturing a solid-state imaging device, wherein a three-layer film formed by sequentially stacking the silicon nitride film and the second silicon oxide film is used as a gate insulating film of a charge transfer portion.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4235324A JPH0661470A (en) | 1992-08-11 | 1992-08-11 | Solid-state image sensing device and its manufacture |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4235324A JPH0661470A (en) | 1992-08-11 | 1992-08-11 | Solid-state image sensing device and its manufacture |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0661470A true JPH0661470A (en) | 1994-03-04 |
Family
ID=16984423
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4235324A Pending JPH0661470A (en) | 1992-08-11 | 1992-08-11 | Solid-state image sensing device and its manufacture |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0661470A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6399520B1 (en) | 1999-03-10 | 2002-06-04 | Tokyo Electron Limited | Semiconductor manufacturing method and semiconductor manufacturing apparatus |
| US6847079B2 (en) | 1999-09-13 | 2005-01-25 | Mitsubishi Denki Kabushiki Kaisha | Semiconductor device having a stacked gate insulation film and a gate electrode and manufacturing method thereof |
-
1992
- 1992-08-11 JP JP4235324A patent/JPH0661470A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6399520B1 (en) | 1999-03-10 | 2002-06-04 | Tokyo Electron Limited | Semiconductor manufacturing method and semiconductor manufacturing apparatus |
| US6470824B2 (en) | 1999-03-10 | 2002-10-29 | Tokyo Electron Limited | Semiconductor manufacturing apparatus |
| US6847079B2 (en) | 1999-09-13 | 2005-01-25 | Mitsubishi Denki Kabushiki Kaisha | Semiconductor device having a stacked gate insulation film and a gate electrode and manufacturing method thereof |
| US7180131B2 (en) | 1999-09-13 | 2007-02-20 | Mitsubishi Denki Kabushiki Kaisha | Semiconductor device having a stacked gate insulation film and a gate electrode and manufacturing method thereof |
| US7229882B2 (en) | 1999-09-13 | 2007-06-12 | Mitsubishi Denki Kabushiki Kaisha | Method of manufacturing a field effect semiconductor device having a stacked gate insulation film and a gate electrode |
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