JP3756894B2 - Nitride film quality improving method and semiconductor device manufacturing method - Google Patents

Nitride film quality improving method and semiconductor device manufacturing method Download PDF

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JP3756894B2
JP3756894B2 JP2003169460A JP2003169460A JP3756894B2 JP 3756894 B2 JP3756894 B2 JP 3756894B2 JP 2003169460 A JP2003169460 A JP 2003169460A JP 2003169460 A JP2003169460 A JP 2003169460A JP 3756894 B2 JP3756894 B2 JP 3756894B2
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nitride film
film
annealing
temperature
chlorine
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JP2005005589A (en
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岳志 星
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Toshiba Corp
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
    • H01L21/02518—Deposited layers
    • H01L21/02521—Materials
    • H01L21/02538—Group 13/15 materials
    • H01L21/0254—Nitrides
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
    • H01L21/02612—Formation types
    • H01L21/02617—Deposition types
    • H01L21/0262—Reduction or decomposition of gaseous compounds, e.g. CVD
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/28—Manufacture of electrodes on semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/268
    • H01L21/283—Deposition of conductive or insulating materials for electrodes conducting electric current
    • H01L21/285—Deposition of conductive or insulating materials for electrodes conducting electric current from a gas or vapour, e.g. condensation
    • H01L21/28506—Deposition of conductive or insulating materials for electrodes conducting electric current from a gas or vapour, e.g. condensation of conductive layers
    • H01L21/28512—Deposition of conductive or insulating materials for electrodes conducting electric current from a gas or vapour, e.g. condensation of conductive layers on semiconductor bodies comprising elements of Group IV of the Periodic System
    • H01L21/28556—Deposition of conductive or insulating materials for electrodes conducting electric current from a gas or vapour, e.g. condensation of conductive layers on semiconductor bodies comprising elements of Group IV of the Periodic System by chemical means, e.g. CVD, LPCVD, PECVD, laser CVD
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
    • H01L21/324—Thermal treatment for modifying the properties of semiconductor bodies, e.g. annealing, sintering

Description

【０００１】
【発明が属する技術分野】
本発明は、半導体装置等に用いられる窒化膜の膜質改善方法及びその窒化膜を用いた半導体装置の製造方法に関する。
【０００２】
【従来の技術】
従来、ＳｉＨ２Ｃｌ２、ＳｉＣｌ４、Ｓｉ２Ｃｌ６のような塩素含有Ｓｉ原料ガスとＮＨ３ガスとを用いたＬＰＣＶＤ（Low Pressure Chemical Vapor Deposition）法により窒化膜を成膜していた。このＬＰＣＶＤ法では、６５０℃〜８００℃の成膜温度が一般的に用いられていた。
【０００３】
【発明が解決しようとする課題】
しかしながら、熱履歴（Thermal Budget）を低減するために、上記成膜温度を６００℃以下に低温化した場合、窒化膜中に不純物として塩素や水素が多く残存してしまい、窒化膜の膜質が劣化してしまうという問題があった。
さらに、かかる窒化膜を半導体装置に適用した場合、窒化膜中に残存する塩素が他の素子に拡散してしまい、半導体装置の信頼性が低下する可能性があった。例えば、ゲート電極側壁のサイドウォールを窒化膜により形成する場合には、窒化膜の不純物がゲート電極に拡散してしまい、ゲート電極中の不純物濃度が変化してしまうという問題があった。
【０００４】
本発明は、上記従来の課題を解決するためになされたもので、成膜温度を増加させることなく、窒化膜中の塩素含有量を低減することを目的とする。
【０００５】
【課題を解決するための手段】
本発明に係る窒化膜の膜質改善方法は、基板上に、６００℃以下の温度で塩素含有Ｓｉ原料ガスを用いてＬＰＣＶＤ法により窒化膜層を成膜する成膜工程と、
前記窒化膜層が成膜された前記基板を前記成膜工程の温度より低く、３００℃以上の温度でアニールし、前記窒化膜層から塩素を除去するアニール工程と、
を含み、
前記成膜工程と前記アニール工程とを繰り返し行うことによって、複数の前記窒化膜層からなる窒化膜を形成することを特徴とするものである。
【０００６】
本発明に係る膜質改善方法において、前記成膜工程で、前記窒化膜層を１ｎｍ〜２０ｎｍの膜厚で成膜することが好適である。
【０００７】
本発明に係る膜質改善方法において、前記アニール工程で用いられるアニールガスは、ＮＨ３、Ｎ２、Ｈ２、Ｏ２、ＮＯ２の何れかを含むことが好適である。
【０００８】
本発明に係る膜質改善方法において、前記成膜工程と前記アニール工程とを同一の製造装置内で連続して行うことが好適である。
【０００９】
本発明に係る半導体装置の製造方法は、基板上に、半導体要素を形成する工程と、
前記半導体要素上に、６００℃以下の温度で塩素含有Ｓｉ原料ガスを用いてＬＰＣＶＤ法により窒化膜層を成膜する成膜工程と、
前記窒化膜層が成膜された前記基板を前記成膜工程の温度より低く、３００℃以上の温度でアニールし、前記窒化膜層から塩素を除去するアニール工程と、
を含み、
前記成膜工程と前記アニール工程とを繰り返し行うことによって、複数の前記窒化膜層からなる窒化膜を形成することを特徴とするものである。
【００１０】
本発明に係る半導体装置の製造方法においても、前記成膜工程で、前記窒化膜層を１ｎｍ〜２０ｎｍの膜厚で成膜することが好適である。
【００１１】
本発明に係る半導体装置の製造方法においても、前記アニール工程で用いられるアニールガスは、ＮＨ３、Ｎ２、Ｈ２、Ｏ２、ＮＯ２の何れかを含むことが好適である。
【００１２】
本発明に係る半導体装置の製造方法においても、前記成膜工程と前記アニール工程とを同一の製造装置内で連続して行うことが好適である。
【００１３】
本発明に係る半導体装置の製造方法において、前記半導体要素はゲート電極であり、
前記窒化膜を形成した後、前記窒化膜をエッチングすることにより前記ゲート電極の側壁にサイドウォールを形成する工程を更に含むことが好適である。
【００１４】
【発明の実施の形態】
以下、図面を参照して本発明の実施の形態について説明する。図中、同一または相当する部分には同一の符号を付してその説明を簡略化ないし省略することがある。
【００１５】
実施の形態１．
図１は、本発明の実施の形態１による窒化膜の膜質改善方法を説明するための工程断面図である。
先ず、図１（ａ）に示すように、基板１０としてのシリコン基板上に、Ｓｉ２Ｃｌ６（ＨＣＤ：Hexa-Chloro-Disilane）のような塩素含有ガスを用いて６００℃以下の成膜温度でＬＰＣＶＤ法により第１層目の窒化膜（以下「１層目窒化膜」という。）２１を形成する。
ここで、１層目窒化膜２１の成膜条件は、例えば、Ｓｉ２Ｃｌ６流量：１０〜５０ｓｃｃｍ；ＮＨ３流量：３００〜１０００ｓｃｃｍ；圧力：１Ｔｏｒｒ；温度：４５０℃である。また、１層目窒化膜２１の形成膜厚は、以下に述べるアニール処理を考慮すると、例えば、１ｎｍ〜２０ｎｍが好適であり、１ｎｍ〜１０ｎｍがより好適である。このように、Ｓｉ原料として塩素含有ガスを用い、６００℃以下の低温で成膜された１層目窒化膜２１の表面には、不純物としての塩素３１や水素が多く存在する。なお、上述したように、１層目窒化膜２１の形成膜厚を１ｎｍ〜２０ｎｍ程度に薄くすることにより、１層目窒化膜２１中に残存する塩素３１は少なく、ほとんどの塩素３１は１層目窒化膜２１の表面に存在する。
【００１６】
次に、図１（ｂ）に示すように、アニールガス３２としてＮＨ３を用いて、アニール処理を行う。このアニール処理により、１層目窒化膜２１表面に存在する塩素３１とＮＨ３３２とが反応して、例えば、ＨＣｌ等の反応生成物３３が生成する。この反応生成物３３は１層目窒化膜２１表面から脱離する。
ここで、アニールガス３２としては、上記ＮＨ３以外に、Ｎ２，Ｈ２を用いることができ、さらに１層目窒化膜２１の膜質に影響しない限度においてＯ２，Ｎ２Ｏを用いることができる。ＮＨ３の代わりにＮ２をアニールガス３２として用いた場合、１層目窒化膜２１の表面に残存し、成膜工程で未反応であった塩素含有ガスやＮＨ３がそのまま除去されると考えられる。また、Ｏ２またはＮＯ２をアニールガス３２として用いた場合、１層目窒化膜２１の表面に残存する水素と反応してＨ２Ｏを生成し、その中に塩素が含まれた状態で除去されると考えられる。
また、アニール処理は、ＬＰＣＶＤ装置を用いて行うことができる。すなわち、成膜処理とアニール処理を同一の製造装置を用いて連続して行うことができる。アニール処理条件は、例えば、ＮＨ３流量；３００〜１０００ｓｃｃｍ；圧力：１Ｔｏｒｒ；温度：４００℃である。
また、アニール処理時間は、１層目窒化膜２１の膜厚や、該窒化膜２１における塩素３１の減少量に応じて適宜決定すればよく、例えば、３０ｓｅｃである。また、アニール処理の温度は、上記４００℃に限らず、窒化膜２１の成膜温度以下で且つ３００℃以上であればよい。
【００１７】
その後、図１（ａ）に示す成膜工程と、図１（ｂ）に示すアニール工程とを、所望の膜厚の窒化膜が得られるまで交互に繰り返し実行する。これにより、図１（ｃ）に示すように、多層の窒化膜２１，２２，…，２ｎからなる窒化膜が形成される。すなわち、図２に示すように、成膜工程（処理時間：１５ｓｅｃ）とアニール工程（３０ｓｅｃ）とを１周期とし、これを複数回繰り返すことにより、所望の膜厚を有する窒化膜が得られる。２５０周期行ってトータル膜厚が約７０ｎｍの窒化膜を形成した際、その窒化膜中の塩素含有量が、１回の成膜工程で形成した窒化膜中の塩素含有量と比べて約３０％減少したことを本発明者は確認した。
【００１８】
以上説明したように、本実施の形態１では、塩素含有ガスを用いて６００℃以下の温度でＬＰＣＶＤ法により１層目窒化膜２１を成膜した後、アニール処理を行って該１層目窒化膜２１表面に残存する塩素３１を除去した。そして、成膜工程とアニール工程を繰り返すことにより、多層の窒化膜２１，２２，…，２ｎからなる窒化膜を形成した。これにより、最終的な窒化膜中の塩素３１を減少させることができ、窒化膜の膜質を改善することができる。
また、窒化膜２１，２２，…，２ｎの成膜工程とアニール工程とを、同一の製造装置（ＬＰＣＶＤ装置）で行うことにより、スループットを向上させることができる。さらに、成膜温度とアニール温度とを同一温度にすることにより、スループットを更に向上させることができる。
【００１９】
なお、本実施の形態１では、塩素含有のＳｉ原料ガスとしてＳｉ２Ｃｌ６を用いたが、これに限らず、ＳｉＨ２Ｃｌ２、ＳｉＣｌ４を用いることができる。
【００２０】
実施の形態２．
図３は、本発明の実施の形態２による半導体装置の製造方法を説明するための工程断面図である。
本実施の形態２は、前述した実施の形態１の膜質改善方法を、半導体装置の製造方法に適用した一例である。
【００２１】
先ず、図３（ａ）に示すように、基板１０としてのシリコン基板上に、熱酸化法を用いてゲート絶縁膜４１としてのゲート酸化膜を形成する。次に、ゲート絶縁膜４１上にポリシリコン膜を形成し、該ポリシリコン膜をパターニングすることにより、ポリシリコン膜からなるゲート電極（半導体要素）４２を形成する。なお、ゲート電極４２は、ポリシリコン膜とシリサイド膜との積層構造のように、その構造は任意であってもよい。
【００２２】
次に、図３（ｂ）に示すように、ゲート電極４２上に、Ｓｉ２Ｃｌ６およびＮＨ３を用いて成膜温度４５０℃でＬＰＣＶＤ法により１層目窒化膜４３を形成する。１層目窒化膜４３の成膜条件及び膜厚は、前述した実施の形態１と同様であるので、説明を省略する。このように、Ｓｉ原料として塩素含有ガスを用い、６００℃以下の低温で成膜された１層目窒化膜４３の表面には、不純物としての塩素４４や水素が多く残存する。
【００２３】
次に、図３（ｃ）に示すように、アニールガス４５としてＮＨ３を用いてアニール処理を行う。これにより、１層目窒化膜４３表面に残存する塩素４４とアニールガス４５とが反応して、反応生成物４６を生成する。この反応生成物４６は１層目窒化膜４３から離脱する。
本アニール処理の処理条件は、前述した実施の形態１と同様であるので、説明を省略する。
【００２４】
さらに、図３（ｂ）に示した成膜工程と、図３（ｃ）に示したアニール工程とを交互に繰り返し行う。これにより、図３（ｄ）に示すように、所望の膜厚の窒化膜４７が得られる。すなわち、図２に示すようなシーケンスを行うことにより、多層膜からなる窒化膜４７が得られる。各アニール工程で、膜表面に残存する塩素４４が除去されるため、窒化膜４７中に含まれる塩素４４の量は低減する。
【００２５】
次に、図３（ｅ）に示すように、ドライエッチング等の異方性エッチングすることにより、ゲート電極４２の側壁に窒化膜からなるサイドウォール４８を形成する。
【００２６】
以上説明したように、本実施の形態２では、ゲート電極４２を覆うように、塩素含有ガスを用いて６００℃以下の温度でＬＰＣＶＤ法により１層目窒化膜４３を成膜した後、アニール処理を行って該窒化膜４３表面に残存する塩素４４を除去した。さらに、成膜工程とアニール工程を繰り返し行うことにより、多層の窒化膜からなり所望の膜厚を有する窒化膜４７を形成した。これにより、窒化膜４７中の塩素４４を減少させることができ、窒化膜４７の膜質を改善することができる。
さらに、窒化膜４７をエッチングすることにより、ゲート電極４２の側壁を覆うサイドウォール４８を形成した。膜質が改善された窒化膜からなるサイドウォール４８は塩素濃度が低いため、後工程で熱が加わった場合でも、サイドウォール４８からゲート電極４２等に不純物が拡散しない。従って、膜質が改善された窒化膜を半導体装置に適用することにより、半導体装置の信頼性を向上させることができる。
【００２７】
なお、本実施の形態２では、半導体要素としてのゲート電極４２上に窒化膜４７を形成する場合について説明したが、これに限らず、例えば、窒化膜をライナーとして形成する場合についても適用できる。
【００２８】
【発明の効果】
本発明によれば、成膜温度を増加させることなく、窒化膜中の塩素含有量を低減することができる。
【図面の簡単な説明】
【図１】 本発明の実施の形態１による窒化膜の膜質改善方法を説明するための工程断面図である。
【図２】 本発明の実施の形態１において、窒化膜の形成シーケンスを示す図である。
【図３】 本発明の実施の形態２による半導体装置の製造方法を説明するための工程断面図である。
【符号の説明】
１０ 基板（シリコン基板）
２１，４３ １層目窒化膜
２２ ２層目窒化膜
２ｎ ｎ層目窒化膜
３１，４４ 塩素
４１ ゲート絶縁膜（ゲート酸化膜）
４２ ゲート電極
４７ 窒化膜
４８ サイドウォール[0001]
[Technical field to which the invention belongs]
The present invention relates to a method for improving the quality of a nitride film used in a semiconductor device or the like and a method for manufacturing a semiconductor device using the nitride film.
[0002]
[Prior art]
Conventionally, a nitride film has been formed by LPCVD (Low Pressure Chemical Vapor Deposition) method using a chlorine-containing Si source gas such as SiH 2 Cl 2 , SiCl 4 , and Si 2 Cl 6 and NH 3 gas. In this LPCVD method, a film forming temperature of 650 ° C. to 800 ° C. is generally used.
[0003]
[Problems to be solved by the invention]
However, when the film formation temperature is lowered to 600 ° C. or lower in order to reduce the thermal history, a large amount of chlorine and hydrogen remains as impurities in the nitride film, and the film quality of the nitride film deteriorates. There was a problem of doing.
Further, when such a nitride film is applied to a semiconductor device, chlorine remaining in the nitride film may diffuse into other elements, possibly reducing the reliability of the semiconductor device. For example, when the sidewall of the gate electrode side wall is formed of a nitride film, there is a problem in that the impurity of the nitride film diffuses into the gate electrode and the impurity concentration in the gate electrode changes.
[0004]
The present invention has been made to solve the above-described conventional problems, and an object thereof is to reduce the chlorine content in a nitride film without increasing the film formation temperature.
[0005]
[Means for Solving the Problems]
A method for improving a film quality of a nitride film according to the present invention includes a film forming step of forming a nitride film layer on a substrate by LPCVD using a chlorine-containing Si source gas at a temperature of 600 ° C. or lower;
Annealing the substrate on which the nitride film layer is formed at a temperature lower than the temperature of the film formation process and at a temperature of 300 ° C. or higher, and removing chlorine from the nitride film layer ;
Including
A nitride film composed of a plurality of nitride film layers is formed by repeatedly performing the film forming step and the annealing step.
[0006]
In the film quality improving method according to the present invention, it is preferable that the nitride film layer is formed to a thickness of 1 nm to 20 nm in the film forming step.
[0007]
In the film quality improving method according to the present invention, it is preferable that the annealing gas used in the annealing step includes any of NH 3 , N 2 , H 2 , O 2 , and NO 2 .
[0008]
In the film quality improvement method according to the present invention, it is preferable that the film forming step and the annealing step are continuously performed in the same manufacturing apparatus.
[0009]
A method of manufacturing a semiconductor device according to the present invention includes a step of forming a semiconductor element on a substrate,
A film forming step of forming a nitride film layer on the semiconductor element by LPCVD using a chlorine-containing Si source gas at a temperature of 600 ° C. or lower;
Annealing the substrate on which the nitride film layer is formed at a temperature lower than the temperature of the film formation process and at a temperature of 300 ° C. or higher, and removing chlorine from the nitride film layer ;
Including
A nitride film composed of a plurality of nitride film layers is formed by repeatedly performing the film forming step and the annealing step.
[0010]
Also in the method of manufacturing a semiconductor device according to the present invention, it is preferable that the nitride film layer is formed to a thickness of 1 nm to 20 nm in the film forming step.
[0011]
Also in the method for manufacturing a semiconductor device according to the present invention, it is preferable that the annealing gas used in the annealing step includes any of NH 3 , N 2 , H 2 , O 2 , and NO 2 .
[0012]
Also in the method for manufacturing a semiconductor device according to the present invention, it is preferable that the film forming step and the annealing step are continuously performed in the same manufacturing apparatus.
[0013]
In the method for manufacturing a semiconductor device according to the present invention, the semiconductor element is a gate electrode,
It is preferable that the method further includes forming a sidewall on the sidewall of the gate electrode by etching the nitride film after forming the nitride film.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof may be simplified or omitted.
[0015]
Embodiment 1 FIG.
FIG. 1 is a process cross-sectional view for explaining a film quality improvement method for a nitride film according to Embodiment 1 of the present invention.
First, as shown in FIG. 1A, a film forming temperature of 600 ° C. or lower is formed on a silicon substrate as the substrate 10 using a chlorine-containing gas such as Si 2 Cl 6 (HCD: Hexa-Chloro-Disilane). Then, a first nitride film (hereinafter referred to as “first nitride film”) 21 is formed by LPCVD.
Here, the film formation conditions of the first nitride film 21 are, for example, Si 2 Cl 6 flow rate: 10 to 50 sccm; NH 3 flow rate: 300 to 1000 sccm; pressure: 1 Torr; temperature: 450 ° C. In addition, the film thickness of the first nitride film 21 is, for example, preferably 1 nm to 20 nm, more preferably 1 nm to 10 nm, considering the annealing treatment described below. As described above, a large amount of chlorine 31 and hydrogen as impurities exist on the surface of the first nitride film 21 formed at a low temperature of 600 ° C. or lower using a chlorine-containing gas as a Si raw material. As described above, by reducing the thickness of the first nitride film 21 to about 1 nm to 20 nm, there is little chlorine 31 remaining in the first nitride film 21, and most of the chlorine 31 is one layer. Present on the surface of the eye nitride film 21.
[0016]
Next, as shown in FIG. 1B, annealing is performed using NH 3 as the annealing gas 32. By this annealing treatment, chlorine 31 and NH 3 32 existing on the surface of the first-layer nitride film 21 react to generate a reaction product 33 such as HCl. This reaction product 33 is desorbed from the surface of the first nitride film 21.
Here, as the annealing gas 32, N 2 and H 2 can be used in addition to the NH 3 , and O 2 and N 2 O can be used as long as the quality of the first nitride film 21 is not affected. it can. When N 2 is used as the annealing gas 32 instead of NH 3 , it is considered that the chlorine-containing gas and NH 3 remaining on the surface of the first nitride film 21 and unreacted in the film forming process are removed as they are. It is done. Further, when O 2 or NO 2 is used as the annealing gas 32, it reacts with hydrogen remaining on the surface of the first layer nitride film 21 to generate H 2 O, which is removed in a state where chlorine is contained therein. It is thought that it is done.
The annealing treatment can be performed using an LPCVD apparatus. That is, the film forming process and the annealing process can be continuously performed using the same manufacturing apparatus. The annealing conditions are, for example, NH 3 flow rate; 300 to 1000 sccm; pressure: 1 Torr; temperature: 400 ° C.
Further, the annealing treatment time may be appropriately determined according to the thickness of the first nitride film 21 and the amount of decrease of chlorine 31 in the nitride film 21 and is, for example, 30 sec. The temperature of the annealing process is not limited to 400 ° C., and may be not more than the deposition temperature of the nitride film 21 and not less than 300 ° C.
[0017]
Thereafter, the film forming process shown in FIG. 1A and the annealing process shown in FIG. 1B are alternately and repeatedly performed until a nitride film having a desired film thickness is obtained. As a result, as shown in FIG. 1C, a nitride film composed of multilayer nitride films 21, 22,..., 2n is formed. That is, as shown in FIG. 2, a film-forming process (processing time: 15 sec) and an annealing process (30 sec) are set as one cycle, and a nitride film having a desired film thickness is obtained by repeating this several times. When a nitride film having a total film thickness of about 70 nm is formed after 250 cycles, the chlorine content in the nitride film is about 30% compared to the chlorine content in the nitride film formed in one film formation process. The present inventor confirmed that it decreased.
[0018]
As described above, in the first embodiment, the first layer nitride film 21 is formed by LPCVD using a chlorine-containing gas at a temperature of 600 ° C. or lower, and then annealed to perform the first layer nitridation. Chlorine 31 remaining on the surface of the film 21 was removed. Then, by repeating the film forming process and the annealing process, a nitride film composed of multilayer nitride films 21, 22,..., 2n was formed. Thereby, the chlorine 31 in the final nitride film can be reduced, and the film quality of the nitride film can be improved.
In addition, the throughput can be improved by performing the deposition process and the annealing process of the nitride films 21, 22,..., 2n with the same manufacturing apparatus (LPCVD apparatus). Furthermore, the throughput can be further improved by setting the film formation temperature and the annealing temperature to the same temperature.
[0019]
In the first embodiment, Si 2 Cl 6 is used as the chlorine-containing Si source gas. However, the present invention is not limited to this, and SiH 2 Cl 2 and SiCl 4 can be used.
[0020]
Embodiment 2. FIG.
FIG. 3 is a process sectional view for explaining the method for manufacturing a semiconductor device according to the second embodiment of the present invention.
The second embodiment is an example in which the film quality improvement method of the first embodiment described above is applied to a method for manufacturing a semiconductor device.
[0021]
First, as shown in FIG. 3A, a gate oxide film as a gate insulating film 41 is formed on a silicon substrate as a substrate 10 using a thermal oxidation method. Next, a polysilicon film is formed on the gate insulating film 41, and the polysilicon film is patterned to form a gate electrode (semiconductor element) 42 made of the polysilicon film. The gate electrode 42 may have an arbitrary structure, such as a stacked structure of a polysilicon film and a silicide film.
[0022]
Next, as shown in FIG. 3B, a first nitride film 43 is formed on the gate electrode 42 by LPCVD using Si 2 Cl 6 and NH 3 at a film formation temperature of 450 ° C. The film forming conditions and film thickness of the first nitride film 43 are the same as those in the first embodiment described above, and thus the description thereof is omitted. As described above, a large amount of chlorine 44 and hydrogen as impurities remain on the surface of the first nitride film 43 formed at a low temperature of 600 ° C. or lower using a chlorine-containing gas as a Si raw material.
[0023]
Next, as shown in FIG. 3C, annealing is performed using NH 3 as the annealing gas 45. As a result, the chlorine 44 remaining on the surface of the first-layer nitride film 43 reacts with the annealing gas 45 to generate a reaction product 46. This reaction product 46 is detached from the first nitride film 43.
The processing conditions for the annealing treatment are the same as those in the first embodiment described above, and a description thereof will be omitted.
[0024]
Further, the film forming process shown in FIG. 3B and the annealing process shown in FIG. 3C are alternately repeated. Thereby, a nitride film 47 having a desired film thickness is obtained as shown in FIG. That is, the nitride film 47 made of a multilayer film is obtained by performing the sequence as shown in FIG. In each annealing step, chlorine 44 remaining on the film surface is removed, so that the amount of chlorine 44 contained in the nitride film 47 is reduced.
[0025]
Next, as shown in FIG. 3E, a sidewall 48 made of a nitride film is formed on the sidewall of the gate electrode 42 by anisotropic etching such as dry etching.
[0026]
As described above, in the second embodiment, the first nitride film 43 is formed by LPCVD at a temperature of 600 ° C. or lower using a chlorine-containing gas so as to cover the gate electrode 42, and then annealed. The chlorine 44 remaining on the surface of the nitride film 43 was removed. Further, by repeatedly performing the film forming process and the annealing process, a nitride film 47 made of a multilayer nitride film and having a desired film thickness was formed. Thereby, the chlorine 44 in the nitride film 47 can be reduced, and the film quality of the nitride film 47 can be improved.
Further, by etching the nitride film 47, a sidewall 48 covering the side wall of the gate electrode 42 was formed. Since the side wall 48 made of a nitride film with improved film quality has a low chlorine concentration, impurities are not diffused from the side wall 48 to the gate electrode 42 or the like even when heat is applied in a later step. Therefore, the reliability of the semiconductor device can be improved by applying the nitride film with improved film quality to the semiconductor device.
[0027]
In the second embodiment, the case where the nitride film 47 is formed on the gate electrode 42 serving as a semiconductor element has been described. However, the present invention is not limited to this.
[0028]
【The invention's effect】
According to the present invention, the chlorine content in the nitride film can be reduced without increasing the film formation temperature.
[Brief description of the drawings]
FIG. 1 is a process cross-sectional view for explaining a nitride film quality improvement method according to a first embodiment of the present invention.
FIG. 2 is a diagram showing a nitride film formation sequence in the first embodiment of the present invention.
FIG. 3 is a process sectional view for explaining the method for manufacturing the semiconductor device according to the second embodiment of the present invention;
[Explanation of symbols]
10 Substrate (silicon substrate)
21, 43 First layer nitride film 22 Second layer nitride film 2n Nth layer nitride film 31, 44 Chlorine 41 Gate insulating film (gate oxide film)
42 Gate electrode 47 Nitride film 48 Side wall

Claims (6)

基板上に、６００℃以下の温度で塩素含有Ｓｉ原料ガスを用いてＬＰＣＶＤ法により窒化膜層を成膜する成膜工程と、
前記窒化膜層が成膜された前記基板を前記成膜工程の温度より低く、３００℃以上の温度でアニールし、前記窒化膜層から塩素を除去するアニール工程と、
を含み、
前記成膜工程と前記アニール工程とを繰り返し行うことによって、複数の前記窒化膜層からなる窒化膜を形成することを特徴とする窒化膜の膜質改善方法。A film forming step of forming a nitride film layer on the substrate by LPCVD using a chlorine-containing Si source gas at a temperature of 600 ° C. or lower;
Annealing the substrate on which the nitride film layer is formed at a temperature lower than the temperature of the film formation process and at a temperature of 300 ° C. or higher, and removing chlorine from the nitride film layer ;
Including
A nitride film quality improvement method comprising: forming a nitride film composed of a plurality of the nitride film layers by repeatedly performing the film forming step and the annealing step. 請求項１に記載の膜質改善方法において、
前記成膜工程で、前記窒化膜層を１ｎｍ〜２０ｎｍの膜厚で成膜することを特徴とする窒化膜の膜質改善方法。In the film quality improvement method according to claim 1,
A method for improving the quality of a nitride film, wherein the nitride film layer is formed to a thickness of 1 nm to 20 nm in the film forming step. 請求項１又は２に記載の膜質改善方法において、
前記アニール工程で用いられるアニールガスは、ＮＨ３、Ｎ２、Ｈ２、Ｏ２、ＮＯ２の何れかを含むことを特徴とする窒化膜の膜質改善方法。In the film quality improvement method according to claim 1 or 2,
An annealing gas used in the annealing step includes any one of NH 3 , N 2 , H 2 , O 2 , and NO 2 . 請求項１から３の何れかに記載の膜質改善方法において、
前記成膜工程と前記アニール工程とを同一の製造装置内で連続して行うことを特徴とする窒化膜の膜質改善方法。In the film quality improvement method in any one of Claim 1 to 3,
A method for improving the quality of a nitride film, wherein the film forming step and the annealing step are continuously performed in the same manufacturing apparatus. 基板上に、半導体要素を形成する工程と、
前記半導体要素上に、６００℃以下の温度で塩素含有Ｓｉ原料ガスを用いてＬＰＣＶＤ法により窒化膜層を成膜する成膜工程と、
前記窒化膜層が成膜された前記基板を前記成膜工程の温度より低く、３００℃以上の温度でアニールし、前記窒化膜層から塩素を除去するアニール工程と、
を含み、
前記成膜工程と前記アニール工程とを繰り返し行うことによって、複数の前記窒化膜層からなる窒化膜を形成することを特徴とする半導体装置の製造方法。Forming a semiconductor element on a substrate;
A film forming step of forming a nitride film layer on the semiconductor element by LPCVD using a chlorine-containing Si source gas at a temperature of 600 ° C. or lower;
Annealing the substrate on which the nitride film layer is formed at a temperature lower than the temperature of the film formation process and at a temperature of 300 ° C. or higher, and removing chlorine from the nitride film layer ;
Including
A method of manufacturing a semiconductor device, wherein a nitride film including a plurality of nitride film layers is formed by repeatedly performing the film forming step and the annealing step. 請求項５に記載の製造方法において、
前記半導体要素はゲート電極であり、
前記窒化膜を形成した後、前記窒化膜をエッチングすることにより前記ゲート電極の側壁にサイドウォールを形成する工程を更に含むことを特徴とする半導体装置の製造方法。In the manufacturing method of Claim 5,
The semiconductor element is a gate electrode;
A method of manufacturing a semiconductor device, further comprising: forming a sidewall on a sidewall of the gate electrode by etching the nitride film after forming the nitride film.
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