JP3672226B2 - Intramembrane ion content measuring method and apparatus - Google Patents

Description

【００４１】
ここで、ε₀ は真空の誘電率、εoxは絶縁膜１０２の比誘電率、ρ₀ は膜内イオンの密度（個／ｃｍ³ ）、Ｇは絶縁膜１０２と測定用電極２０１とのギャップ、ｄoxは絶縁膜１０２の厚みである。
【００４２】
上記の式（１）において、膜内イオンの密度ρ₀ 以外の値は既知なので、電圧のシフト量ΔＶ_F1からρ₀ の値を決定することができる。なお、式（１）を用いた膜内イオン量の算出は、ホストコントローラ３９０（図１）内部の膜内イオン量決定部３９２によって実行される。
【００４３】
以上のようにして、図３（Ａ−１）に示す初期状態の絶縁膜１０２中に存在していた膜内イオンＭ１⁺ の量を決定することができる。
【００４４】
ところで、図２〜図４においては、絶縁膜１０２中に１種類の元素Ｍ１が含まれており、その一部がイオン化している場合の膜内イオンＭ１⁺ の量の決定方法について説明したが、実際には、絶縁膜１０２中に複数種類の元素が含まれており、各元素の一部がイオン化している場合がある。
【００４５】
図５は、絶縁膜中に複数種類の膜内イオンが含まれている場合の膜内イオン量の決定手順を示すフローチャートである。また、図６は、半導体ウエハの絶縁膜中に存在する複数種類の膜内イオンの量を測定する際の処理を示す説明図である。
【００４６】
図５のステップＴ１〜ステップＴ４の処理については、図２のステップＳ１〜Ｓ４とほぼ同じである。図６（Ａ−１）は、図５の処理を開始する前における半導体ウエハ１００の表面近傍を示している。図示するように、絶縁膜１０２には、２種類の不純物元素Ｍ１，Ｍ２が含まれており、それぞれの一部はイオン化して膜内イオンＭ１⁺ ，Ｍ２⁺ となっている。なお、第１の膜内イオンＭ１⁺ としては、ナトリウムイオンＮａ⁺ を想定できる。また、第２の膜内イオンＭ２⁺ としては、カリウムイオンＫ⁺ やリチウムイオンＬｉ⁺ などを想定できると考えられている。図６（Ａ−２）は、ステップＴ１において、図６（Ａ−１）に示す半導体ウエハ１００について１回目のＣ−Ｖ測定を行ったときの第１のＣ−Ｖ曲線Ｇ１を示している。
【００４７】
ステップＴ２において、半導体ウエハ１００に電界を与えた状態で、第１の波長範囲の光Ｌ１を照射すると、図６（Ｂ−１）に示すように、絶縁膜１０２中に含まれる膜内イオンＭ１⁺ ，Ｍ２⁺ が双方とも中和される。
【００４８】
図７は、絶縁膜中に含まれる膜内イオンＭ１⁺ ，Ｍ２⁺ が双方とも中和されるときの様子を示す説明図である。図７に示すように、シリコン酸化膜１０２中には、Ｎａに関係した第１のトラップ準位Ｅ_T1とともに、さらに深い準位に第２のトラップ準位Ｅ_T2が存在している。これは、上記のＬｉやＫに関係したトラップ準位と考えられている。図４で説明したように、半導体ウエハ１００に照射する第１の光Ｌ１が４．２５ｅＶ以上の光である場合には、励起された電子ｅ^- はシリコン酸化膜１０２のエネルギ障壁（４．２５ｅＶ）を越え、シリコン酸化膜１０２中の第１および第２のトラップに捕獲される。トラップに捕獲された電子は、ナトリウムイオンＮａ⁺ や他のイオン（Ｌｉ⁺ ，Ｋ⁺ ）を中和させる。
【００４９】
ステップＴ３（図５）では、２回目のＣ−Ｖ測定を行い、第２のＣ−Ｖ曲線を得る。図６（Ｂ−２）は、図６（Ｂ−１）に示す半導体ウエハ１００について２回目のＣ−Ｖ測定を行ったときの第２のＣ−Ｖ曲線Ｇ２を示している。なお、図６（Ｂ−２）には、ステップＴ１で得られた第１のＣ−Ｖ曲線Ｇ１も示されている。
【００５０】
ステップＴ４では、第１のＣ−Ｖ曲線Ｇ１と第２のＣ−Ｖ曲線Ｇ２とから、図６（Ａ−１）に示す初期状態の絶縁膜１０２中に存在した全膜内イオンＭ１⁺ ，Ｍ２⁺ の総量を求める。具体的には、第１および第２のＣ−Ｖ曲線Ｇ１，Ｇ２のフラットバンド電圧のシフト量ΔＶ_G1から、式（１）と同様の式を用いて決定することができる。
【００５１】
次に、ステップＴ５では、ステップＴ２において与えた電界と逆方向の電界を半導体ウエハ１００に与えた状態で、第２の波長範囲の光Ｌ２を照射する。この第２の波長範囲の光Ｌ２を照射することにより、図７の第１のトラップ準位Ｅ_T1に捕獲されていた電子が励起され、再放出される。これにより、中和された膜内イオンが再度イオン化される。
【００５２】
図８は、中和された膜内イオンが再度イオン化されるときの様子を示す説明図である。ステップＴ５において照射する第２の波長範囲の光Ｌ２は、中和された膜内イオンＭ１⁺ ，Ｍ２⁺ のうち、中和された第１の膜内イオンＭ１⁺ のみをイオン化させるような波長を有している。第１の膜内イオンＭ１⁺ がナトリウムイオンＮａ⁺ である場合には、図８に示す約２．４ｅＶのエネルギを有する光、すなわち、約５１７ｎｍの光を照射する。このような光を照射すると、第１のトラップ準位Ｅ_T1に捕獲された電子ｅ^- が励起される。このとき、中和された第１の膜内イオンＭ１⁺ がイオン化され、電子ｅ^- が再放出される。すなわち、中和されたナトリウムイオンは、再度イオン化される。ところで、ステップＴ５においては、測定用電極２０１（図１）に試料台１７０に対して負の電圧を印加して、半導体ウエハ１００にステップＴ２と逆方向の電界が与えられている。このとき、シリコン酸化膜１０２の伝導帯の底のエネルギＥ_i は、図示するように右下がりに傾斜する。放出された電子ｅ^- は、この電界によって半導体基板１０１側に容易に移動するため、中和された膜内イオンのイオン化を比較的短時間で行うことが可能となる。
【００５３】
図６（Ｃ−１）は、ステップＴ５（図５）において、図６（Ｂ−１）に示す中和された膜内イオンＭ１⁺ ，Ｍ２⁺ のうち、第１の膜内イオンＭ１⁺ のみがイオン化された様子を示している。このとき、イオン化される第１の膜内イオンＭ１⁺ の量は、図６（Ａ−１）に示す初期状態の絶縁膜１０２中に含まれていた第１の膜内イオンＭ１⁺ の量とほぼ同じである。なお、ステップＴ５においてイオン化される元素は、初期状態において既にイオン化していた元素と同じであると考えられている。
【００５４】
ステップＴ６では、３回目のＣ−Ｖ測定を行う。図６（Ｃ−２）は、図６（Ｃ−１）に示す半導体ウエハ１００について３回目のＣ−Ｖ測定を行ったときの第３のＣ−Ｖ曲線Ｇ３を示している。なお、図６（Ｃ−２）には、ステップＴ１，Ｔ３で得られた第１，第２のＣ−Ｖ曲線Ｇ１，Ｇ２も示されている。
【００５５】
ステップＴ７では、第２のＣ−Ｖ曲線Ｇ２と第３のＣ−Ｖ曲線Ｇ３とから、再度イオン化された第１の膜内イオンＭ１⁺ の量を決定する。具体的には、第２および第３のＣ−Ｖ曲線Ｇ２，Ｇ３のフラットバンド電圧のシフト量ΔＶ_G2から式（１）と同様の式を用いて決定する。
【００５６】
ステップＴ８〜Ｔ１０では、ステップＴ５〜Ｔ７の処理と同様の処理を繰り返す。ステップＴ８では、ステップＴ５と同様に、半導体ウエハ１００にステップＴ２と逆方向の電界を与えた状態で、第３の波長範囲の光Ｌ３を照射する。図８に示すように、ステップＴ５において照射する第３の波長範囲の光Ｌ３は、中和された第２の膜内イオンＭ２⁺ のみを再度イオン化させるような波長を有している。第３の光Ｌ３を照射すると、第２のトラップ準位Ｅ_T2に捕獲された電子ｅ^- が励起され、この結果、中和された第２の膜内イオンＭ２⁺ がイオン化され、電子ｅ^- が再放出される。ここで、第３の波長範囲の光Ｌ３は、第２の波長範囲の光Ｌ２より短波長の光である。このように、照射する光を次第に短波長の光に変更することにより、各トラップ準位に捕獲された電子ｅ^- を順次再放出させ、中和された膜内イオンを順次イオン化させることができる。
【００５７】
図６（Ｄ−１）は、ステップＴ８（図５）において、図６（Ｃ−１）に示す中和された第２の膜内イオンＭ２⁺ がイオン化された様子を示している。なお、イオン化された膜内イオンＭ２⁺ の量は、図６（Ａ−１）に示す初期状態の絶縁膜１０２中に含まれていた第２の膜内イオンＭ２⁺ の量とほぼ同じである。
【００５８】
ステップＴ９では、４回目のＣ−Ｖ測定を行う。図６（Ｄ−２）は、図６（Ｄ−１）に示す半導体ウエハ１００について４回目のＣ−Ｖ測定を行ったときの第４のＣ−Ｖ曲線Ｇ４を示している。なお、図６（Ｂ−２）には、ステップＴ１，Ｔ３，Ｔ６で得られた第１〜第３のＣ−Ｖ曲線Ｇ１〜Ｇ３も示されている。ただし、図６（Ｄ−１）と図６（Ａ−１）とを比較して分かるように、絶縁膜１０２中に存在する膜内イオンＭ１⁺ ，Ｍ２⁺ の量はそれぞれの状態で同じであるので、第１のＣ−Ｖ曲線Ｇ１と第４のＣ−Ｖ曲線Ｇ４とは重なっている。
【００５９】
ステップＴ１０では、第３のＣ−Ｖ曲線Ｇ３と第４のＣ−Ｖ曲線Ｇ４とから、イオン化された第２の膜内イオンＭ２⁺ の量を決定する。具体的には、第３および第４のＣ−Ｖ曲線Ｇ３，Ｇ４のフラットバンド電圧のシフト量ΔＶ_G3から式（１）と同様の式を用いて決定する。
【００６０】
なお、図５では、第２の膜内イオンＭ２⁺ の量は、第３および第４のＣ−Ｖ曲線Ｇ３，Ｇ４から決定しているが、図６に示すように、絶縁膜１０２中に２種類の膜内イオンＭ１⁺ ，Ｍ２⁺ のみが存在している場合には、第１および第３のＣ−Ｖ曲線Ｇ１，Ｇ３から求めることも可能である。
【００６１】
また、図５では、絶縁膜１０２中に２種類の膜内イオンのみが存在している場合について説明しているが、絶縁膜中に３種類以上の膜内イオンを含む場合にも、特定種類の膜内イオンの量を分離して決定することが可能である。この場合には、ステップＴ５〜Ｔ７，ステップＴ８〜Ｔ１０と同様の処理を繰り返し行えばよい。ただし、中和された特定種類の膜内イオンを再度イオン化する際には、照射する光を次第に短波長に変更しながら行う必要がある。このようにすれば、絶縁膜中に複数種類の膜内イオンが含まれている場合においても、特定種類の膜内イオンの量を分離して決定することが可能である。
【００６２】
以上の説明からも分かるように、本実施例の膜内イオン量測定装置ＭＤ１（図１）における測定用電極２０１と金属製の試料台１７０と容量測定器３３０とホストコントローラ３９０との測定系が、本発明の電気特性測定部に相当する。また、光源装置３００と光ファイバ３０２とレンズ３０４との照射光学系、および、測定用電極２０１と金属製の試料台１７０と容量測定器３３０とホストコントローラ３９０との電界付与系が、本発明の膜内イオン中和部に相当する。
【００６３】
Ｂ．第２実施例：
図９は、本発明の第２実施例としての膜内イオン量測定装置の構成を示す説明図である。図９に示す測定装置ＭＤ２は、半導体ウエハ１００の表面光電圧（ＳＰＶ：Surface Photo Voltage）を非接触で測定する機能を有している。
【００６４】
本実施例の光源装置３００ａは、膜内イオンを中和させたりイオン化させたりするための光源に加え、ＳＰＶ測定用の光源を備えている。ＳＰＶ測定用の光源としては、約４５０ｎｍ〜１２００ｎｍの光を射出する光源が利用される。また、光ファイバ３０２の経路の途中には、光源装置３００ａから射出されるＳＰＶ測定用の連続光を断続光に変換するためのチョッパ３０６が追加されている。チョッパ３０６は、内部に遮光板を備えており、遮光板を軸３０６ａを中心として回転させることにより断続光を生成する。
【００６５】
本実施例の測定装置ＭＤ２では、図１の容量測定器３３０に代えて、ＳＰＶ測定器３４０が用いられている。ＳＰＶ測定器３４０は、半導体ウエハ１００に電圧を印加する機能を有するとともに、断続光の照射にともない発生するＳＰＶ信号（後述する）を測定する機能を有している。このため、ＳＰＶ測定器３４０には、チョッパ３０６から同期信号ＳＹＮＣが供給されている。
【００６６】
また、測定装置ＭＤ２では、図１の測定装置ＭＤ１に備えられていた発光素子１５０、受光素子１６０、光量測定器３２０が省略されている。これは、ＳＰＶ測定においては、測定用電極２０１と半導体ウエハ１００とのギャップＧは、０．２ｍｍ程度と比較的大きいからである。なお、本実施例では、測定用電極２０１と半導体ウエハ１００との間をエアギャップとしているが、これに代えて、マイラーフィルムなどの透光性の絶縁膜を用いるようにしてもよい。
【００６７】
図９の測定装置ＭＤ２を用いる場合にも、図１の測定装置ＭＤ１と同様の手順、すなわち、図２の手順に従って絶縁膜中の膜内イオン量を測定することが可能である。ただし、第１実施例においては、ステップＳ１，Ｓ３の測定として非接触Ｃ−Ｖ測定を行っているが、本実施例においては、電圧を挿引しながらＳＰＶ測定を行う。
【００６８】
ところで、ＳＰＶ測定は、以下のような現象を利用したものである。半導体ウエハに断続光を照射すると、半導体ウエハの表面付近に電子正孔対が発生する。このとき、半導体ウエハの内部に空乏層が形成されていると、光の照射によって発生した電子正孔対が、空乏層内の電界により移動して半導体ウエハの表面の電圧を変化させる。この電圧変化がＳＰＶ信号としてＳＰＶ測定器３４０によって測定される。
【００６９】
このＳＰＶ信号値は、基板中の空乏層幅が大きいほど大きくなる。換言すれば、ＳＰＶ信号値は、空乏層の容量が小さいほど大きくなる。したがって、印加電圧を挿引しながらＳＰＶ信号を測定すれば、Ｃ−Ｖ測定と同じように、印加電圧Ｖと合成容量Ｃとの関係を得ることが可能である。
【００７０】
このようにしても、図２のステップＳ４において膜内イオン量を決定することが可能である。また、絶縁膜中に複数種類の膜内イオンが含まれている場合についても、図５の手順に従って絶縁膜中に存在するそれぞれの膜内イオン量を分離して決定することが可能である。
【００７１】
なお、本実施例の膜内イオン量測定装置ＭＤ２（図９）における測定用電極２０１と金属製の試料台１７０とＳＰＶ測定器３４０とホストコントローラ３９０との測定系、および、ＳＰＶ信号を発生させるための光源を含む光源装置３００ａと光ファイバ３０２とレンズ３０４との照射光学系が、本発明の電気特性測定部に相当する。また、中和およびイオン化のための光源を含む光源装置３００ａと光ファイバ３０２とレンズ３０４との照射光学系、および、測定用電極２０１と金属製の試料台１７０とＳＰＶ測定器３４０とホストコントローラ３９０との電界付与系が、本発明の膜内イオン中和部に相当する。
【００７２】
Ｃ．第３実施例：
図１０は、本発明の第３実施例としての膜内イオン量測定装置の構成を示す説明図である。図１０に示す測定装置ＭＤ３は、半導体ウエハ１００の表面電位を非接触で測定する機能を有している。
【００７３】
測定装置ＭＤ３は、図１の測定装置ＭＤ１における容量測定器３３０に代えて、振動容量電位測定器３５０が備えられている。振動容量電位測定器３５０は、半導体ウエハ１００に電圧を印加する機能を有するとともに、周知のケルビン法（後述する）を用いた振動容量電位を測定する機能を有している。
【００７４】
また、この測定装置ＭＤ３では、図９と同様に、図１の測定装置ＭＤ１に備えられていた発光素子１５０、受光素子１６０、光量測定器３２０が省略されている。これは、ケルビン法を用いた測定においても、半導体ウエハ１００の表面１００ａと、測定用電極２０１とのギャップＧは、２ｍｍ程度と比較的大きいからである。
【００７５】
本実施例の測定装置ＭＤ３では、半導体ウエハ１００上にコロナ電荷を付加するためのコロナ電荷生成部４００が追加されている。なお、半導体ウエハ１００は、移動ステージ１９０を−Ｙ方向に移動させることによってコロナ電荷生成部４００に搬送される。
【００７６】
コロナ電荷生成部４００は、直流電源４１０と、略中空円筒状のイオン噴出ノズル４２０と、イオン噴出ノズル４２０にガスＧｓを供給するためのガスボンベ４２２と、ガスＧｓの流量を調整するための流量調節器４２４とを備えている。イオン噴出ノズル４２０の中央には、針状のイオン発生用電極４２６が設けられている。このイオン発生用電極４２６は、直流電源４１０に接続されている。イオン発生用電極４２６に高電圧が印加されて放電（コロナ放電）が発生すると、イオン噴出ノズル４２０内に供給されたガスＧｓがイオン化される。イオン化した帯電分子は、イオン噴出ノズル４２０の先端の開口部から噴出し、半導体ウエハ１００上に堆積することによって半導体ウエハ１００の表面を帯電させる。なお、半導体ウエハ１００の表面を正帯電させる帯電分子としては、ヒドロニウムイオンＨ₃Ｏ⁺を用いることができ、また、負帯電させる帯電分子としては、炭酸イオンＣＯ₃ ^2-を用いることができる。
【００７７】
この測定装置ＭＤ３を用いる場合にも、図１の測定装置ＭＤ１と同様の手順、すなわち、図２の手順に従って絶縁膜中の膜内イオン量を測定することが可能である。ただし、第１実施例においては、ステップＳ１，Ｓ３の測定として非接触Ｃ−Ｖ測定を行っているが、本実施例においては、Ｃ−Ｖ測定における電圧挿引に代えて、半導体ウエハ１００の絶縁膜１０２上に付加する電荷量を変更させつつ、振動容量電位計法（ケルビン法）によるウエハの表面電位測定を行う。
【００７８】
図１１は、ケルビン法を用いた表面電位測定の概略を示す説明図である。半導体ウエハ１００と測定用電極２０１とをエアーギャップを介して対向させた際に、半導体ウエハ１００の表面１００ａでの電位をＶとすると、測定用電極２０１には半導体ウエハ１００と測定用電極２０１との間の容量Ｃｋに応じた電荷Ｑ’（＝Ｃk・Ｖ）が誘導される。このとき圧電アクチュエータ１２０（図１０）により測定用電極２０１を上下に振動させると、容量Ｃｋが変化するため、測定用電極２０１に誘導される電荷量Ｑ’も時間的に変化する。この結果、測定用電極２０１に出入りする電流ｉが発生し、電流ｉは、振動容量電位測定器３５０の内部に備えられた電流計により検出される。このとき、振動容量電位測定器３５０の内部に備えられた電圧発生器により、測定用電極２０１にバイアス電圧Ｖを加えて、測定用電極２０１と半導体ウエハの表面１００ａとの電位差を０となるようにすれば電極２０１を振動させても電流ｉは発生しなくなる。そのときのバイアス電圧Ｖから半導体ウエハの表面電位を知ることができる。なお、ケルビン法は、周知のものであり、Z.Physin,115,296(1940年)に所載のB.ギゼ(Gysae)及びS.ワーゲナー(Wagener)の論文に詳細に開示されている。
【００７９】
半導体ウエハ１００の表面電位は、半導体基板１０１内に形成される空乏層の幅に応じて変化する。したがって、絶縁膜１０２上の電荷量を変化させることによって空乏層幅を変化させれば、空乏層幅に応じた表面電位を知ることができる。すなわち、電荷量に応じた表面電位を測定することによって、Ｃ−Ｖ測定と同様に、電荷量と合成容量Ｃとの関係を得ることができる。
【００８０】
このようにしても、図２のステップＳ４において膜内イオン量を決定することが可能である。また、絶縁膜中に複数種類の膜内イオンが含まれている場合についても、図５の手順に従って絶縁膜中に存在するそれぞれの膜内イオン量を分離して決定することが可能である。
【００８１】
ところで、本実施例では、図２のステップＳ２において、第１および第２実施例の正の電圧印加に代えて、正のコロナ帯電分子が付加された状態で、第１の波長範囲の光を照射する。半導体ウエハ１００の絶縁膜１０２上に正電荷を付加すると、正電圧を印加するのと同様に、半導体ウエハ１００には電界が与えられる。ところが、図４に示すように、励起された電子ｅ^- は、絶縁膜１０２表面にも到達するので、絶縁膜１０２表面に蓄積された正電荷を中和する。このため、絶縁膜１０２表面の正電荷量が減少し、第１の波長範囲の光Ｌ１を照射するのに伴い、半導体ウエハ１００に与えられる電界が次第に小さくなってしまう。このような場合には、膜内イオンの中和に要する時間が長くなるという問題が生じ得る。このため、ステップＳ２（図２）においては、絶縁膜１０２表面に、膜内イオンの中和に十分な量のコロナ帯電分子を付加しておくことが好ましい。
【００８２】
また、図２のステップＳ２において、膜内イオンを中和した後には、絶縁膜１０２表面に残存する電荷量を正確に把握することができないので、一旦、絶縁膜１０２表面の電荷を除去する必要がある。本実施例では、第１の波長範囲の光Ｌ１を十分に長い時間照射することによって、半導体基板１０１から電子を供給し続け、絶縁膜１０２表面の帯電分子を中和するようにしている。ただし、この場合にも、絶縁膜１０２表面の帯電分子が完全に中和されているか否かは不明であるので、光照射による電荷除去に代えて、純粋リンスを行うことによって除去するようにしてもよい。
【００８３】
なお、本実施例の膜内イオン量測定装置ＭＤ３（図１０）における測定用電極２０１と金属製の試料台１７０と振動容量電位測定器３５０とホストコントローラ３９０との測定系が、本発明の電気特性測定部に相当する。また、光源装置３００と光ファイバ３０２とレンズ３０４との照射光学系、および、コロナ電荷生成部４００による電界付与系が、本発明の膜内イオン中和部に相当する。
【００８４】
以上説明したように、本発明においては、絶縁膜中の膜内イオンを中和させる際に、半導体ウエハに第１の波長範囲の光が照射されるとともに電界が与えられる。したがって、膜内イオンの中和を比較的短時間に行うことが可能となり、この結果、初期状態の絶縁膜中に存在していた膜内イオンの量を効率よく測定することが可能となる。
【００８５】
また、絶縁膜中に複数種類の膜内イオンが含まれている場合には、半導体ウエハに第２の波長範囲の光を照射するとともに、逆方向の電界を与えている。これにより、中和された複数種類の膜内イオンのうち、特定種類の膜内イオンのみを比較的短時間でイオン化させることが可能となる。この結果、初期状態の絶縁膜中に存在していた特定膜内イオンの量を効率よく測定することが可能となる。
【００８６】
なお、この発明は上記の実施例や実施形態に限られるものではなく、その要旨を逸脱しない範囲において種々の態様において実施することが可能であり、例えば次のような変形も可能である。
【００８７】
（１）第１実施例では、Ｃ−Ｖ測定は、測定用電極２０１を半導体ウエハ１００に接触させない非接触測定で行われているが、測定用電極２０１を半導体ウエハ１００の絶縁膜表面に押しつけることにより接触測定で行ってもよい。また、接触Ｃ−Ｖ測定としては、測定用電極２０１に代えて、液体金属（例えば、ＨｇやＩｎＧａ）と液体金属に接触させる測定プローブとを用いてもよい。この液体金属と測定プローブとの組み合わせも本発明の測定用電極としての機能を有する。なお、非接触Ｃ−Ｖ測定を行えば、接触Ｃ−Ｖ測定の場合と比べ、半導体ウエハ１００の表面の損傷を低減することができるという利点がある。
【００８８】
（２）第１，第２実施例では、膜内イオンを中和させる工程（図２のステップＳ２，図５のステップＴ２）および中和した膜内イオンを再度イオン化させる工程（図５のステップＴ５，Ｔ８）において、測定用電極２０１に電圧を印加することにより半導体ウエハ１００に電界を与えている。しかし、第３実施例のように、半導体ウエハ１００の表面を帯電させることにより電界を与えるようにしてもよい。
【００８９】
（３）第１実施例では、電気的特性値として、Ｃ−Ｖ曲線から得られるフラットバンド電圧Ｖｆｂを用いているが、他の測定値を利用してもよい。例えば、半導体基板と絶縁膜との界面においてフェルミ準位と真性フェルミ準位とが一致する「ミッドギャップ電圧」と呼ばれる測定値を用いてもよい。
【００９０】
（４）上記実施例では、本発明の測定手法として、Ｃ−Ｖ測定や、表面光電圧測定を利用する測定や、振動容量電位測定を利用する測定などを用いているが、他の測定手法を用いてもよい。一般に、本発明における測定手法としては、半導体ウエハの絶縁膜中に含まれる膜内イオンに関連する半導体ウエハの電気的特性値を測定できるようなものであればよい。
【図面の簡単な説明】
【図１】本発明の第１実施例としての膜内イオン量測定装置を示す説明図である。
【図２】半導体ウエハの絶縁膜中に存在する膜内イオンの量の決定手順を示すフローチャートである。
【図３】半導体ウエハの絶縁膜中に存在する膜内イオンの量を測定する際の処理を示す説明図である。
【図４】絶縁膜中の膜内イオンＭ１⁺ が中和されるときの様子を示す説明図である。
【図５】絶縁膜中に複数種類の膜内イオンが含まれている場合の膜内イオン量の決定手順を示すフローチャートである。
【図６】半導体ウエハの絶縁膜中に存在する複数種類の膜内イオンの量を測定する際の処理を示す説明図である。
【図７】絶縁膜中に含まれる膜内イオンＭ１⁺ ，Ｍ２⁺ が双方とも中和されるときの様子を示す説明図である。
【図８】中和された膜内イオンが再度イオン化されるときの様子を示す説明図である。
【図９】本発明の第２実施例としての膜内イオン量測定装置の構成を示す説明図である。
【図１０】本発明の第３実施例としての膜内イオン量測定装置の構成を示す説明図である。
【図１１】ケルビン法を用いた表面電位測定の概略を示す説明図である。
【符号の説明】
１００…半導体ウエハ
１００ａ…表面
１０１…半導体基板（シリコン基板）
１０２…絶縁膜（シリコン酸化膜）
１１０…ステッピングモータ
１２０…圧電アクチュエータ
１３０…架台
１４０…プリズム
１４０ａ…底面
１５０…発光素子
１６０…受光素子
１７０…試料台
１９０…ステージ
１９０…移動ステージ
２０１…測定用電極
３００，３００ａ…光源装置
３０２…光ファイバ
３０４…レンズ
３０６…チョッパ
３０６ａ…軸
３１０…Ｚ位置制御装置
３２０…光量測定器
３３０…容量測定器
３４０…ＳＰＶ測定器
３５０…振動容量電位測定器
３８０…ステージ制御装置
３９０…ホストコントローラ
３９２…膜内イオン量決定部
４００…コロナ電荷生成部
４１０…直流電源
４２０…イオン噴出ノズル
４２２…ガスボンベ
４２４…流量調節器
４２６…イオン発生用電極
ＭＤ１，ＭＤ２，ＭＤ３…膜内イオン量測定装置[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for measuring the amount of ions in a film contained in an insulating film of a semiconductor wafer.
[0002]
[Prior art]
In the manufacturing process of a semiconductor wafer, an alkali metal ion (Na) is contained in an insulating film formed on the surface of the semiconductor wafer.⁺, K⁺, Li⁺) Or the like (hereinafter referred to as “in-film ions”). Since these in-film ions deteriorate the stability of the semiconductor wafer, there is a demand for measuring the amount of in-film ions.
[0003]
The amount of in-film ions present in the insulating film is the first electrical characteristic value in the state where the in-film ions are present in the insulating film and the second value in the state where the in-film ions are not present in the insulating film. It can obtain | require by measuring the electrical property value. Conventionally, the state in which no in-film ions exist in the insulating film has been realized by irradiating the semiconductor wafer with light to neutralize the in-film ions. Such a method for measuring the amount of ions in the membrane is described in detail in, for example, Japanese Patent Application Laid-Open No. 11-126811 disclosed by the applicant of the present application.
[0004]
[Problems to be solved by the invention]
However, the conventional technique has a problem that it takes a relatively long time to neutralize ions in the membrane, and the amount of ions in the membrane cannot be measured efficiently.
[0005]
The present invention has been made to solve the above-described problems in the prior art, and an object thereof is to provide a technique capable of efficiently measuring the amount of in-film ions present in an insulating film of a semiconductor wafer. And
[0006]
[Means for solving the problems and their functions and effects]
In order to solve at least a part of the above-described problems, the method of the present invention is a method for measuring the amount of ions in a film existing in an insulating film formed on the surface of a semiconductor wafer using a measurement electrode. (A) measuring a first electrical characteristic value of the semiconductor wafer according to a predetermined measurement technique using the measurement electrode in an initial state in which the in-film ions are included in the insulating film; b) irradiating light in a first wavelength range with an electric field applied to the semiconductor wafer to neutralize the in-film ions in the insulating film; and (c) in-film ions are in the middle. A step of measuring a second electrical characteristic value of the semiconductor wafer in accordance with the predetermined measurement method in a summed state; and (d) from the first and second electrical characteristic values in the initial state, In the film that was present in the insulating film Characterized in that it comprises the steps of determining the amount of on and.
[0007]
In the method of the present invention, when neutralizing ions in the insulating film, the semiconductor wafer is irradiated with light in the first wavelength range and an electric field is applied. As a result, the amount of ions in the film existing in the insulating film in the initial state can be efficiently measured.
[0008]
In the above method, the insulating film includes a plurality of types of in-film ions, the plurality of types of in-film ions are neutralized in the step (b), and the method further includes: The plurality of types of films neutralized in the step (b) by irradiating the semiconductor wafer with light in the second wavelength range while applying an electric field in a direction opposite to the electric field applied in the step (b). A step of ionizing specific types of in-film ions among the internal ions by an amount substantially equal to the amount of the specific type of in-film ions present in the insulating film in the initial state; and (f) the specific Measuring a third electrical property value of the semiconductor wafer according to the predetermined measurement method in a state where ions of a kind in the film are ionized in the step (e), and (g) the second and second From the electrical characteristics of 3 It is preferable and a step of determining the amount of the insulating layer the particular type of film in the ion that was present in the in the initial state.
[0009]
Thus, in the step (e), when ionizing the neutralized in-film ions, the semiconductor wafer is irradiated with light in the second wavelength range and given an electric field in the opposite direction, whereby a specific kind of film is obtained. Inner ions can be ionized in a relatively short time. As a result, even when a plurality of types of in-film ions are included in the insulating film in the initial state, it is possible to efficiently measure the amount of specific types of in-film ions.
[0010]
Further, in the above method, the steps (e) to (g) are repeated while changing the second wavelength range of the light irradiated in the step (e) to a short wavelength, and the plurality of types of in-film ions It is preferable to provide a step of separating and determining the amount of other specific types of intramembranous ions.
[0011]
By doing this, it is possible to successfully determine the amount of ions of other specific types of ions contained in the insulating film in the initial state.
[0012]
In the above method, the light in the first wavelength range is desirably light in at least a part of a range from about 220 nm to about 295 nm when the insulating film is a silicon oxide film.
[0013]
By doing so, it is possible to neutralize the ions in the silicon oxide film well.
[0014]
In the above method, the predetermined measurement technique may be CV measurement.
[0015]
In the above method, the CV measurement is preferably a non-contact measurement in which the measurement electrode is not brought into contact with the insulating film.
[0016]
Alternatively, in the above method, the predetermined measurement method may use surface photovoltage measurement that measures a surface photovoltage of the semiconductor wafer generated by irradiating the semiconductor wafer with intermittent light.
[0017]
Alternatively, in the above method, the predetermined measurement method uses vibration capacitance potential measurement that measures the surface potential of the semiconductor wafer while temporally changing a gap between the measurement electrode and the semiconductor wafer. May be.
[0018]
As described above, the amount of ions in the membrane can be determined by using various measurement techniques.
[0019]
In the above method, the step (b) may include a step of applying an electric field to the semiconductor wafer by charging the surface of the insulating film.
[0020]
Even in this case, an electric field can be applied to the semiconductor wafer in the step (b).
[0021]
The apparatus of the present invention is an in-film ion amount measuring apparatus for measuring the amount of in-film ions present in an insulating film formed on the surface of a semiconductor wafer using the measuring electrode, and uses the measuring electrode. An electrical property measuring unit for measuring electrical property values of the semiconductor wafer according to a predetermined measurement method, and irradiating the semiconductor wafer with light in a first wavelength range while applying an electric field to the semiconductor wafer. An in-film ion neutralization unit that electrically neutralizes the in-film ions in the film, and the electrical property measurement unit is configured to perform the predetermined operation in an initial state in which the in-film ions are included in the insulating film. The first electrical characteristic value of the semiconductor wafer measured according to the measurement technique and the second electrical characteristic value of the semiconductor wafer measured according to the predetermined measurement technique in a state where the ions in the film are neutralized From the characteristic value, before Characterized in that it comprises a membrane in ion quantity determining section for determining the amount of the film within the ion that was present in the insulating layer in the initial state.
[0022]
By using the apparatus of the present invention, it is possible to efficiently measure the amount of ions in the film existing in the insulating film in the initial state, with the same operations and effects as the above method.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
A. First embodiment:
FIG. 1 is an explanatory view showing an in-membrane ion content measuring apparatus as a first embodiment of the present invention. This measuring device MD1 has a function of measuring the CV characteristics of the semiconductor wafer 100 in a non-contact manner. The measuring device MD1 includes a stepping motor 110, a piezoelectric actuator 120 installed below the stepping motor 110, and a gantry 130 installed further below the piezoelectric actuator 120. A prism 140 is installed on the bottom surface of the gantry 130. A light emitting element 150 such as a GaAlAs laser is fixed to one inclined surface of the gantry 130, and a light receiving element 160 is fixed to the other inclined surface.
[0024]
The bottom surface 140 a of the prism 140 is provided in parallel with the surface (a plane parallel to the XY plane) of the sample table 170 on which the semiconductor wafer 100 is placed. A measuring electrode 201 is formed on the bottom surface 140a of the prism. Below the prism 140, the semiconductor wafer 100 is held on a metal sample stage 170 through a gap G, and the surface 100a of the semiconductor wafer 100 is set to be substantially parallel to the bottom surface 140a of the prism. Yes. In this measuring apparatus MD1, as detailed in Japanese Patent Application Laid-Open No. 4-132236, the tunnel effect of the laser light totally reflected by the bottom surface 140a of the prism is used to perform the non-contact CV measurement. The value of the gap G is measured. The semiconductor wafer 100 is adsorbed and held on a sample stage 170 by a vacuum pump (not shown). The sample stage 170 is fixed on the moving stage 190.
[0025]
An optical fiber 302 for guiding light emitted from the light source device 300 to the semiconductor wafer 100 and a lens 304 are provided in the center of the stepping motor 110, the piezoelectric actuator 120, and the gantry 130. The light emitted from the lens 304 passes through the prism 140 and the measurement electrode 201 and irradiates the semiconductor wafer 100. Here, the measurement electrode 201 is a transparent electrode, and an ITO film (In-Sn oxide film) or the like is used. The light source device 300 includes a light source and a filter or diffraction grating for limiting the wavelength range of light emitted from the light source.
[0026]
A Z position control device 310 is connected to the stepping motor 110 and the piezoelectric actuator 120. The stepping motor 110 and the piezoelectric actuator 120 move the gantry 130 in the z direction (vertical direction) in accordance with a signal input from the Z position control device 310, thereby the measurement electrode 201 and the surface 100 a of the semiconductor wafer 100. The gap G is adjusted. The stepping motor 110 is used for movement (coarse movement) over a relatively large distance, and the piezoelectric actuator 120 is used for movement (fine movement) over a relatively small distance. A light amount measuring device 320 is connected to the light receiving element 160. The light quantity measuring device 320 measures the value of the gap G based on the signal value supplied from the light receiving element 160. Further, a capacitance measuring device 330 is connected to the measuring electrode 201 and the metal sample stage 170. The capacitance measuring device 330 measures the combined capacitance C between the measurement electrode 201 and the sample stage 170. A stage controller 380 is connected to the moving stage 190. The moving stage 190 moves in the XY plane according to a signal input from the stage control device 380. The Z position control device 310, the light amount measurement device 320, the capacitance measurement device 330, and the stage control device 380 are connected to the host controller 390, and the host controller 390 controls the entire measurement device MD1. The in-film ion amount determination unit 392 included in the host controller 390 determines the amount of in-film ions included in the insulating film of the semiconductor wafer 100 by processing the obtained data. As the host controller 390, for example, a personal computer is used.
[0027]
When performing non-contact CV measurement, the Z position control device 310 controls the stepping motor 110 and the piezoelectric actuator 120, and the gap G between the measurement electrode 201 and the surface 100a of the semiconductor wafer becomes a predetermined size. Thus, the measurement electrode 201 is positioned.
[0028]
FIG. 2 is a flowchart showing a procedure for determining the amount of in-film ions present in the insulating film of the semiconductor wafer. In step S1, the first CV measurement is performed on the semiconductor wafer 100 to obtain a first CV curve.
[0029]
FIG. 3 is an explanatory diagram showing processing when measuring the amount of ions in the film existing in the insulating film of the semiconductor wafer. FIG. 3A-1 shows the vicinity of the surface of the semiconductor wafer 100 before the processing of FIG. 2 is started. As illustrated, an insulating film 102 is formed on the semiconductor substrate 101. In the insulating film 102 illustrated in FIG. 3A-1, one kind of impurity element M <b> 1 is included, and part of the element is ionized to form in-film ions M <b> 1.⁺It has become. 3 includes, for example, an n-type silicon substrate as the semiconductor substrate 101, a silicon oxide film as the insulating film 102, and in-film ions M1.⁺As sodium ion Na⁺Can be assumed. A measurement electrode 201 is disposed on the semiconductor wafer 100 with a gap G interposed therebetween.
[0030]
FIG. 3 (A-2) shows a first CV curve F1 when the first CV measurement is performed on the semiconductor wafer 100 shown in FIG. 3 (A-1). In the figure, the flat band voltage Vfb is a voltage corresponding to the flat band capacitance Cfb calculated from the film thickness dox of the insulating film 102 obtained from the CV curve. The flat band voltage Vfb is shifted by the amount of charge existing near the surface of the semiconductor wafer 100.
[0031]
When the first CV curve F1 is obtained in step S1 (FIG. 2), in step S2, light in the first wavelength range is irradiated with an electric field applied to the semiconductor wafer 100. Thereby, in-film ions M1 contained in the insulating film 102⁺Is neutralized. FIG. 3 (B-1) shows the in-membrane ion M1 of FIG. 3 (A-1).⁺Shows the state of being neutralized. In the present embodiment, the in-membrane ion M1⁺The electric field applied when neutralizing is applied by applying a voltage to the measurement electrode 201 used for CV measurement. Specifically, a positive voltage is applied to the measurement electrode 201 with respect to the sample stage 170 (FIG. 1) to apply an electric field to the semiconductor wafer 100. Further, as described above, the light L1 in the first wavelength range (FIG. 3 (B-1)) irradiated when a voltage is applied is irradiated onto the semiconductor wafer 100 via the measurement electrode 201 which is a transparent electrode.
[0032]
FIG. 4 shows in-film ions M1 in the insulating film.⁺It is explanatory drawing which shows a mode when is neutralized. FIG. 4 schematically shows an energy band diagram in the vicinity of the interface between the semiconductor substrate 101 and the insulating film 102. In the figure, the symbol “E_CB"Represents the energy at the bottom of the conduction band of the silicon substrate 101, and the symbol" E "_VB"Indicates the energy at the upper end of the valence band. Also, the symbol “E”_i"Indicates the energy at the bottom of the conduction band of the silicon oxide film 102 as an insulating film.
[0033]
As shown in FIG. 4, when the semiconductor wafer 100 is irradiated with the first light L1, the first light L1 passes through the silicon oxide film 102 and irradiates the silicon substrate 101. Electrons e in the silicon substrate 101^-Are excited by receiving energy from the first light L1. When the first light L1 is 4.25 eV or more, excited electrons e^-Is the energy barrier of the silicon oxide film 102 (the energy E at the bottom of the conduction band of the silicon oxide film 102)._iAnd energy E at the upper end of the valence band of silicon substrate 101_VBDifference). Electrons e beyond the energy barrier of the silicon oxide film 102^-Is trapped in the trap in the silicon oxide film 102. The trap in the silicon oxide film 102 in FIG. 4 is a sodium related trap and is called a Coulomb-induced trap. This trap level E_T1Is the energy E at the bottom of the conduction band of the silicon oxide film 102._iAnd about 2.4 eV below. Electrons e trapped in the trap by Coulomb attractive force^-Is the sodium ion Na⁺To neutralize.
[0034]
In the present embodiment, the wavelength range of the first light L1 is preferably at least part of about 220 nm to about 295 nm, and particularly 221 nm to 292 nm is suitable. When light having such a wavelength range is used, electrons in the silicon substrate 101 can cross the energy barrier of the silicon oxide film 102, and holes in the silicon substrate 101 pass through the silicon oxide film barrier (5.6 eV). In addition, the damage at the interface between the semiconductor and the insulating film due to light irradiation can be reduced. As the light source device 300 that outputs light in such a wavelength range, for example, a xenon lamp that emits light of about 231 nm can be used.
[0035]
Further, in this embodiment, since the electric field is applied to the semiconductor wafer 100 as the semiconductor wafer 100 is irradiated with light, the energy E at the bottom of the conduction band of the silicon oxide film 102 is applied._iIs inclined downward to the left in the figure. Therefore, the electrons e excited from the semiconductor substrate 101^-Can easily reach the surface of the silicon oxide film 102.
[0036]
By the way, in the conventional technique, sodium ion Na is obtained only by light irradiation.⁺To neutralize. However, in this case, at the initial stage of light irradiation, sodium ions Na in the silicon oxide film 102⁺E^-Is successfully attracted to the oxide film side and neutralized, but in the latter stage of light irradiation, neutralization proceeds and electrons e^-Is not attracted to the oxide film side, and all sodium ions Na⁺There was a problem that it took quite a while to neutralize. In this embodiment, as described above, since an electric field is applied along with light irradiation, sodium ions Na in the silicon oxide film 102 are applied.⁺Can be neutralized in a relatively short time.
[0037]
The electric field applied to the semiconductor wafer 100 is preferably several MV / cm or less at which the insulating film does not cause dielectric breakdown. In this embodiment, an electric field of about 0.1 MV / cm is applied. For example, when the thickness dox of the silicon oxide film 102 is 100 nm and the gap G is 350 nm, this electric field is applied by applying a positive voltage of about 15 V to the measurement electrode 201.
[0038]
In step S3 (FIG. 2), a second CV measurement is performed to obtain a second CV curve. FIG. 3B-2 shows a second CV curve F2 when the second CV measurement is performed on the semiconductor wafer 100 shown in FIG. 3B-1. FIG. 3 (B-2) also shows the first CV curve F1 obtained in step S1.
[0039]
In step S4, the initial insulation shown in FIG. 3A-1 is obtained from the first CV curve F1 obtained in step S1 and the second CV curve F2 obtained in step S2. Intramembrane ion M1 present in membrane 102⁺Find the amount of. Specifically, in-membrane ion M1⁺Is the amount of shift ΔV of the flat band voltage of the first and second CV curves F1, F2._F1From this, it can be determined using the following equation (1).
[0040]
[Expression 1]

[0041]
Where ε₀Is the dielectric constant of vacuum, εox is the relative dielectric constant of the insulating film 102, ρ₀ Is the density of ions in the membrane (number / cm^Three ), G is a gap between the insulating film 102 and the measurement electrode 201, and dox is the thickness of the insulating film 102.
[0042]
In the above equation (1), the density ρ of ions in the membrane₀Since values other than are known, the voltage shift amount ΔV_F1To ρ₀The value of can be determined. The calculation of the in-film ion amount using the equation (1) is executed by the in-film ion amount determination unit 392 inside the host controller 390 (FIG. 1).
[0043]
As described above, in-film ions M1 existing in the insulating film 102 in the initial state shown in FIG.⁺The amount of can be determined.
[0044]
In FIGS. 2 to 4, in-film ions M <b> 1 in the case where one kind of element M <b> 1 is contained in the insulating film 102 and a part thereof is ionized.⁺Although the method for determining the amount of each element has been described, actually, there are cases where a plurality of types of elements are included in the insulating film 102 and some of each element is ionized.
[0045]
FIG. 5 is a flowchart showing a procedure for determining the in-film ion amount when a plurality of types of in-film ions are included in the insulating film. FIG. 6 is an explanatory diagram showing a process when measuring the amounts of plural types of in-film ions present in the insulating film of the semiconductor wafer.
[0046]
The processing in steps T1 to T4 in FIG. 5 is almost the same as steps S1 to S4 in FIG. FIG. 6A-1 shows the vicinity of the surface of the semiconductor wafer 100 before the processing of FIG. 5 is started. As shown in the figure, the insulating film 102 includes two types of impurity elements M1 and M2, and a part of each of them is ionized to form in-film ions M1.⁺, M2⁺It has become. The first intramembranous ion M1⁺As sodium ion Na⁺Can be assumed. Further, the second in-membrane ion M2⁺As potassium ion K⁺Lithium ion Li⁺It is thought that it can be assumed. FIG. 6A-2 shows a first CV curve G1 when the first CV measurement is performed on the semiconductor wafer 100 shown in FIG. 6A-1 in step T1. .
[0047]
In step T2, when the semiconductor wafer 100 is irradiated with light L1 in the first wavelength range while an electric field is applied, as shown in FIG. 6B-1, in-film ions M1 included in the insulating film 102⁺, M2⁺Are both neutralized.
[0048]
FIG. 7 shows in-film ions M1 contained in the insulating film.⁺, M2⁺It is explanatory drawing which shows a mode when both are neutralized. As shown in FIG. 7, in the silicon oxide film 102, the first trap level E related to Na is present._T1At the same time, the second trap level E_T2Is present. This is considered to be a trap level related to the above Li and K. As described with reference to FIG. 4, when the first light L1 applied to the semiconductor wafer 100 is 4.25 eV or more, excited electrons e^-Exceeds the energy barrier (4.25 eV) of the silicon oxide film 102 and is captured by the first and second traps in the silicon oxide film 102. Electrons trapped in the trap are sodium ion Na⁺And other ions (Li⁺, K⁺) Is neutralized.
[0049]
In step T3 (FIG. 5), a second CV measurement is performed to obtain a second CV curve. FIG. 6B-2 shows a second CV curve G2 when the second CV measurement is performed on the semiconductor wafer 100 shown in FIG. 6B-1. FIG. 6B-2 also shows the first CV curve G1 obtained in step T1.
[0050]
In Step T4, all the in-film ions M1 present in the insulating film 102 in the initial state shown in FIG. 6A-1 are obtained from the first CV curve G1 and the second CV curve G2.⁺, M2⁺Find the total amount. Specifically, the shift amount ΔV of the flat band voltage of the first and second CV curves G1, G2_G1Therefore, it can be determined using the same expression as Expression (1).
[0051]
Next, in step T5, the semiconductor wafer 100 is irradiated with the light L2 in the second wavelength range in the state where the electric field in the direction opposite to the electric field applied in step T2 is applied. By irradiating the light L2 in the second wavelength range, the first trap level E in FIG._T1The electrons trapped in are excited and re-emitted. Thereby, the neutralized ion in the membrane is ionized again.
[0052]
FIG. 8 is an explanatory diagram showing a state when neutralized in-film ions are ionized again. The light L2 in the second wavelength range irradiated in step T5 is neutralized in-film ions M1.⁺, M2⁺Of these, the neutralized first in-membrane ion M1⁺The wavelength is such that only the ions are ionized. First membrane ion M1⁺Is sodium ion Na⁺, The light having the energy of about 2.4 eV shown in FIG. 8, that is, the light of about 517 nm is irradiated. When such light is irradiated, the first trap level E_T1E captured in^-Is excited. At this time, the neutralized first in-film ion M1⁺Is ionized and electrons e^-Is re-released. That is, the neutralized sodium ion is ionized again. Incidentally, in step T5, a negative voltage is applied to the measurement electrode 201 (FIG. 1) with respect to the sample stage 170, and an electric field in the direction opposite to that in step T2 is applied to the semiconductor wafer 100. At this time, the energy E at the bottom of the conduction band of the silicon oxide film 102_iTilts downward to the right as shown. Emitted electrons e^-Is easily moved to the semiconductor substrate 101 side by this electric field, so that ionization of neutralized in-film ions can be performed in a relatively short time.
[0053]
FIG. 6C-1 shows the neutralized intramembranous ion M1 shown in FIG. 6B-1 in step T5 (FIG. 5).⁺, M2⁺Of these, the first in-film ion M1⁺Only the ionized state is shown. At this time, the first in-film ion M1 to be ionized⁺Of the first in-film ion M1 contained in the insulating film 102 in the initial state shown in FIG.⁺The amount is almost the same. In addition, it is thought that the element ionized in step T5 is the same as the element already ionized in the initial state.
[0054]
In step T6, the third CV measurement is performed. FIG. 6C-2 shows a third CV curve G3 when the third CV measurement is performed on the semiconductor wafer 100 shown in FIG. 6C-1. FIG. 6C-2 also shows first and second CV curves G1 and G2 obtained in steps T1 and T3.
[0055]
In Step T7, the first in-film ion M1 ionized again from the second CV curve G2 and the third CV curve G3.⁺Determine the amount of. Specifically, the flat band voltage shift amount ΔV of the second and third CV curves G2, G3._G2Is determined using the same formula as formula (1).
[0056]
In steps T8 to T10, processing similar to that in steps T5 to T7 is repeated. In step T8, as in step T5, the semiconductor wafer 100 is irradiated with light L3 in the third wavelength range in the state where an electric field in the direction opposite to that in step T2 is applied. As shown in FIG. 8, the light L3 in the third wavelength range irradiated in step T5 is neutralized second in-film ion M2.⁺Only have such a wavelength that only ionizes again. When the third light L3 is irradiated, the second trap level E_T2E captured in^-Is excited and, as a result, neutralized second intramembrane ion M2⁺Is ionized and electrons e^-Is re-released. Here, the light L3 in the third wavelength range is light having a shorter wavelength than the light L2 in the second wavelength range. In this way, by gradually changing the light to be irradiated to light having a short wavelength, the electrons e trapped in each trap level^-Can be sequentially re-released, and the neutralized ions in the membrane can be sequentially ionized.
[0057]
FIG. 6D-1 shows the second neutralized ion M2 neutralized in step T8 (FIG. 5) shown in FIG. 6C-1.⁺Shows the state of being ionized. The ionized in-film ion M2⁺Of the second in-film ion M2 contained in the insulating film 102 in the initial state shown in FIG.⁺The amount is almost the same.
[0058]
In step T9, the fourth CV measurement is performed. FIG. 6D-2 shows a fourth CV curve G4 when the fourth CV measurement is performed on the semiconductor wafer 100 shown in FIG. 6D-1. FIG. 6B-2 also shows the first to third CV curves G1 to G3 obtained in steps T1, T3, and T6. However, as can be seen by comparing FIG. 6D-1 and FIG. 6A-1, in-film ions M1 present in the insulating film 102⁺, M2⁺Is the same in each state, so the first CV curve G1 and the fourth CV curve G4 overlap.
[0059]
In Step T10, ionized second in-film ions M2 are obtained from the third CV curve G3 and the fourth CV curve G4.⁺Determine the amount of. Specifically, the shift amount ΔV of the flat band voltage of the third and fourth CV curves G3 and G4._G3Is determined using the same formula as formula (1).
[0060]
In FIG. 5, the second in-film ion M2⁺Is determined from the third and fourth CV curves G3 and G4. As shown in FIG. 6, two types of in-film ions M1 are included in the insulating film 102.⁺, M2⁺Can be obtained from the first and third CV curves G1 and G3.
[0061]
FIG. 5 illustrates the case where only two types of in-film ions are present in the insulating film 102, but the specific type can also be used when three or more types of in-film ions are included in the insulating film. It is possible to determine the amount of ions in the membrane separately. In this case, the same processing as in steps T5 to T7 and steps T8 to T10 may be repeated. However, when ionizing a specific type of in-film ion that has been neutralized again, it is necessary to gradually change the irradiation light to a shorter wavelength. In this way, even when a plurality of types of in-film ions are included in the insulating film, it is possible to separately determine the amount of specific types of in-film ions.
[0062]
As can be understood from the above description, the measurement system of the measurement electrode 201, the metal sample stage 170, the capacity measurement device 330, and the host controller 390 in the intramembrane ion content measurement device MD1 (FIG. 1) of the present embodiment is provided. This corresponds to the electrical property measuring section of the present invention. In addition, the irradiation optical system of the light source device 300, the optical fiber 302, and the lens 304, and the electric field application system of the measurement electrode 201, the metal sample stage 170, the capacitance measuring device 330, and the host controller 390 are included in the present invention. Corresponds to the ion neutralization part in the membrane.
[0063]
B. Second embodiment:
FIG. 9 is an explanatory diagram showing the configuration of an in-membrane ion content measuring apparatus as a second embodiment of the present invention. The measuring apparatus MD2 shown in FIG. 9 has a function of measuring a surface photovoltage (SPV) of the semiconductor wafer 100 in a non-contact manner.
[0064]
The light source device 300a of this embodiment includes a light source for SPV measurement in addition to a light source for neutralizing or ionizing in-film ions. As a light source for SPV measurement, a light source that emits light of about 450 nm to 1200 nm is used. Further, a chopper 306 for converting continuous light for SPV measurement emitted from the light source device 300a into intermittent light is added in the middle of the path of the optical fiber 302. The chopper 306 includes a light shielding plate inside, and generates intermittent light by rotating the light shielding plate around an axis 306a.
[0065]
In the measuring apparatus MD2 of the present embodiment, an SPV measuring instrument 340 is used instead of the capacity measuring instrument 330 of FIG. The SPV measuring instrument 340 has a function of applying a voltage to the semiconductor wafer 100 and a function of measuring an SPV signal (described later) that is generated when the intermittent light is irradiated. For this reason, the synchronization signal SYNC is supplied from the chopper 306 to the SPV measuring device 340.
[0066]
Further, in the measuring apparatus MD2, the light emitting element 150, the light receiving element 160, and the light quantity measuring device 320 provided in the measuring apparatus MD1 in FIG. 1 are omitted. This is because in the SPV measurement, the gap G between the measurement electrode 201 and the semiconductor wafer 100 is relatively large at about 0.2 mm. In this embodiment, an air gap is formed between the measurement electrode 201 and the semiconductor wafer 100. However, instead of this, a light-transmitting insulating film such as a Mylar film may be used.
[0067]
Even when the measuring device MD2 of FIG. 9 is used, it is possible to measure the amount of ions in the insulating film in accordance with the same procedure as the measuring device MD1 of FIG. 1, that is, the procedure of FIG. However, in the first embodiment, the non-contact CV measurement is performed as the measurement in steps S1 and S3. However, in the present embodiment, the SPV measurement is performed while the voltage is subtracted.
[0068]
By the way, the SPV measurement utilizes the following phenomenon. When the semiconductor wafer is irradiated with intermittent light, electron-hole pairs are generated near the surface of the semiconductor wafer. At this time, if a depletion layer is formed inside the semiconductor wafer, electron-hole pairs generated by light irradiation move due to an electric field in the depletion layer and change the voltage on the surface of the semiconductor wafer. This voltage change is measured by the SPV measuring device 340 as an SPV signal.
[0069]
The SPV signal value increases as the depletion layer width in the substrate increases. In other words, the SPV signal value increases as the depletion layer capacity decreases. Therefore, if the SPV signal is measured while the applied voltage is being subtracted, the relationship between the applied voltage V and the combined capacitance C can be obtained in the same manner as the CV measurement.
[0070]
Even in this way, it is possible to determine the amount of ions in the membrane in step S4 of FIG. Further, even in the case where a plurality of types of in-film ions are included in the insulating film, it is possible to separately determine the amounts of ions in the film existing in the insulating film according to the procedure of FIG.
[0071]
Note that the measurement electrode 201, the metal sample stage 170, the SPV measuring device 340, the host controller 390, and the SPV signal are generated in the in-membrane ion amount measuring device MD2 (FIG. 9) of the present embodiment. The irradiation optical system of the light source device 300a including the light source, the optical fiber 302, and the lens 304 corresponds to the electrical characteristic measurement unit of the present invention. Further, an irradiation optical system including a light source device 300a including a light source for neutralization and ionization, an optical fiber 302, and a lens 304, a measurement electrode 201, a metal sample stage 170, an SPV measuring instrument 340, and a host controller 390. The electric field application system is equivalent to the in-film ion neutralization portion of the present invention.
[0072]
C. Third embodiment:
FIG. 10 is an explanatory diagram showing the configuration of an in-membrane ion content measuring apparatus as a third embodiment of the present invention. A measuring apparatus MD3 shown in FIG. 10 has a function of measuring the surface potential of the semiconductor wafer 100 in a non-contact manner.
[0073]
The measuring device MD3 is provided with a vibration capacitance potential measuring device 350 instead of the capacitance measuring device 330 in the measuring device MD1 of FIG. The vibration capacity potential measuring device 350 has a function of applying a voltage to the semiconductor wafer 100 and a function of measuring a vibration capacity potential using a well-known Kelvin method (described later).
[0074]
Further, in this measuring apparatus MD3, as in FIG. 9, the light emitting element 150, the light receiving element 160, and the light quantity measuring device 320 provided in the measuring apparatus MD1 in FIG. 1 are omitted. This is because even in the measurement using the Kelvin method, the gap G between the surface 100a of the semiconductor wafer 100 and the measurement electrode 201 is relatively large at about 2 mm.
[0075]
In the measuring apparatus MD3 of the present embodiment, a corona charge generator 400 for adding a corona charge on the semiconductor wafer 100 is added. The semiconductor wafer 100 is transferred to the corona charge generation unit 400 by moving the moving stage 190 in the −Y direction.
[0076]
The corona charge generation unit 400 includes a DC power source 410, a substantially hollow cylindrical ion ejection nozzle 420, a gas cylinder 422 for supplying the gas Gs to the ion ejection nozzle 420, and a flow rate adjustment for adjusting the flow rate of the gas Gs. 424. In the center of the ion ejection nozzle 420, a needle-like ion generation electrode 426 is provided. The ion generating electrode 426 is connected to a DC power supply 410. When a high voltage is applied to the ion generation electrode 426 to generate a discharge (corona discharge), the gas Gs supplied into the ion ejection nozzle 420 is ionized. The ionized charged molecules are ejected from the opening at the tip of the ion ejection nozzle 420 and are deposited on the semiconductor wafer 100 to charge the surface of the semiconductor wafer 100. The charged molecule for positively charging the surface of the semiconductor wafer 100 is hydronium ion H_ThreeO⁺In addition, as a charged molecule to be negatively charged, carbonate ion CO_Three ^2-Can be used.
[0077]
Even when this measuring apparatus MD3 is used, it is possible to measure the amount of ions in the insulating film in accordance with the same procedure as the measuring apparatus MD1 of FIG. 1, that is, the procedure of FIG. However, in the first embodiment, the non-contact CV measurement is performed as the measurement in steps S1 and S3. However, in this embodiment, instead of the voltage insertion in the CV measurement, the semiconductor wafer 100 is measured. The surface potential of the wafer is measured by the vibration capacitance potentiometer method (Kelvin method) while changing the amount of charge to be added on the insulating film 102.
[0078]
FIG. 11 is an explanatory diagram showing an outline of surface potential measurement using the Kelvin method. When the potential at the surface 100a of the semiconductor wafer 100 is V when the semiconductor wafer 100 and the measurement electrode 201 are opposed to each other through an air gap, the measurement electrode 201 includes the semiconductor wafer 100 and the measurement electrode 201. A charge Q ′ (= Ck · V) is induced according to the capacitance Ck. At this time, when the measurement electrode 201 is vibrated up and down by the piezoelectric actuator 120 (FIG. 10), the capacitance Ck changes, and the amount of charge Q ′ induced in the measurement electrode 201 also changes with time. As a result, a current i that enters and exits the measurement electrode 201 is generated, and the current i is detected by an ammeter provided inside the vibration capacitance potential measuring device 350. At this time, a bias voltage V is applied to the measuring electrode 201 by a voltage generator provided in the vibration capacitance potential measuring device 350 so that the potential difference between the measuring electrode 201 and the surface 100a of the semiconductor wafer becomes zero. In this case, the current i is not generated even when the electrode 201 is vibrated. The surface potential of the semiconductor wafer can be known from the bias voltage V at that time. The Kelvin method is well known and is disclosed in detail in the papers of B. Gysae and S. Wagener described in Z. Physin, 115, 296 (1940).
[0079]
The surface potential of the semiconductor wafer 100 changes according to the width of the depletion layer formed in the semiconductor substrate 101. Therefore, if the depletion layer width is changed by changing the amount of charge on the insulating film 102, the surface potential corresponding to the depletion layer width can be known. That is, by measuring the surface potential according to the amount of charge, the relationship between the amount of charge and the combined capacitance C can be obtained as in the case of CV measurement.
[0080]
Even in this way, it is possible to determine the amount of ions in the membrane in step S4 of FIG. Further, even in the case where a plurality of types of in-film ions are included in the insulating film, it is possible to separately determine the amounts of ions in the film existing in the insulating film according to the procedure of FIG.
[0081]
By the way, in this embodiment, in step S2 of FIG. 2, instead of applying the positive voltage in the first and second embodiments, the light in the first wavelength range is emitted with the positive corona charged molecules added. Irradiate. When a positive charge is applied on the insulating film 102 of the semiconductor wafer 100, an electric field is applied to the semiconductor wafer 100 as in the case of applying a positive voltage. However, as shown in FIG. 4, excited electrons e^-Since it also reaches the surface of the insulating film 102, it neutralizes positive charges accumulated on the surface of the insulating film 102. For this reason, the amount of positive charge on the surface of the insulating film 102 decreases, and the electric field applied to the semiconductor wafer 100 gradually decreases as the light L1 in the first wavelength range is irradiated. In such a case, there may be a problem that the time required for neutralization of ions in the membrane becomes long. For this reason, in Step S2 (FIG. 2), it is preferable to add a sufficient amount of corona charged molecules to the surface of the insulating film 102 to neutralize ions in the film.
[0082]
Further, since the amount of charge remaining on the surface of the insulating film 102 cannot be accurately grasped after neutralizing ions in the film in step S2 of FIG. 2, it is necessary to remove the charge on the surface of the insulating film 102 once. There is. In this embodiment, the light L1 in the first wavelength range is irradiated for a sufficiently long time, so that electrons are continuously supplied from the semiconductor substrate 101 and the charged molecules on the surface of the insulating film 102 are neutralized. However, in this case as well, since it is unclear whether the charged molecules on the surface of the insulating film 102 are completely neutralized, instead of removing the charge by light irradiation, it is removed by performing a pure rinse. Also good.
[0083]
Note that the measurement system of the measurement electrode 201, the metal sample stage 170, the vibration capacitance potential measurement device 350, and the host controller 390 in the in-membrane ion amount measurement device MD3 (FIG. 10) of the present embodiment is the electric system of the present invention. It corresponds to the characteristic measurement unit. Further, the irradiation optical system of the light source device 300, the optical fiber 302, and the lens 304 and the electric field application system by the corona charge generation unit 400 correspond to the in-film ion neutralization unit of the present invention.
[0084]
As described above, in the present invention, when neutralizing ions in the insulating film, the semiconductor wafer is irradiated with light in the first wavelength range and an electric field is applied. Therefore, the neutralization of ions in the film can be performed in a relatively short time, and as a result, the amount of ions in the film existing in the insulating film in the initial state can be efficiently measured.
[0085]
Further, when a plurality of types of in-film ions are included in the insulating film, the semiconductor wafer is irradiated with light in the second wavelength range and an electric field in the opposite direction is applied. Thereby, it becomes possible to ionize only a specific type of in-film ions among a plurality of types of neutralized in-film ions in a relatively short time. As a result, it is possible to efficiently measure the amount of specific intramural ions present in the insulating film in the initial state.
[0086]
The present invention is not limited to the above examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.
[0087]
(1) In the first embodiment, the CV measurement is performed by non-contact measurement in which the measurement electrode 201 is not brought into contact with the semiconductor wafer 100, but the measurement electrode 201 is pressed against the insulating film surface of the semiconductor wafer 100. It may be performed by contact measurement. Moreover, as a contact CV measurement, it may replace with the electrode 201 for a measurement and may use the measurement probe made to contact a liquid metal (for example, Hg and InGa) and a liquid metal. The combination of the liquid metal and the measurement probe also has a function as the measurement electrode of the present invention. Note that non-contact CV measurement has an advantage that damage to the surface of the semiconductor wafer 100 can be reduced as compared with contact CV measurement.
[0088]
(2) In the first and second embodiments, the step of neutralizing the ions in the membrane (step S2 in FIG. 2 and step T2 in FIG. 5) and the step of ionizing the neutralized ions in the membrane again (step in FIG. 5) In T5 and T8), an electric field is applied to the semiconductor wafer 100 by applying a voltage to the measurement electrode 201. However, an electric field may be applied by charging the surface of the semiconductor wafer 100 as in the third embodiment.
[0089]
(3) In the first embodiment, the flat band voltage Vfb obtained from the CV curve is used as the electrical characteristic value, but other measured values may be used. For example, a measurement value called “mid gap voltage” in which the Fermi level and the intrinsic Fermi level coincide with each other at the interface between the semiconductor substrate and the insulating film may be used.
[0090]
(4) In the above embodiment, C-V measurement, measurement using surface photovoltage measurement, measurement using vibration capacitance potential measurement, etc. are used as the measurement method of the present invention. It may be used. In general, any measurement technique in the present invention may be used as long as it can measure the electrical characteristic value of the semiconductor wafer related to ions in the film contained in the insulating film of the semiconductor wafer.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing an in-membrane ion content measuring apparatus as a first embodiment of the present invention.
FIG. 2 is a flowchart showing a procedure for determining the amount of ions in a film existing in an insulating film of a semiconductor wafer.
FIG. 3 is an explanatory diagram showing a process when measuring the amount of ions in a film existing in an insulating film of a semiconductor wafer.
FIG. 4 In-film ion M1 in an insulating film⁺It is explanatory drawing which shows a mode when is neutralized.
FIG. 5 is a flowchart showing a procedure for determining the amount of ions in a film when a plurality of types of ions in the film are included in the insulating film.
FIG. 6 is an explanatory diagram showing processing when measuring the amounts of a plurality of types of in-film ions existing in an insulating film of a semiconductor wafer.
FIG. 7 shows in-film ions M1 contained in the insulating film.⁺, M2⁺It is explanatory drawing which shows a mode when both are neutralized.
FIG. 8 is an explanatory diagram showing a state when neutralized in-film ions are ionized again.
FIG. 9 is an explanatory diagram showing a configuration of an in-membrane ion content measuring apparatus as a second embodiment of the present invention.
FIG. 10 is an explanatory diagram showing the configuration of an in-membrane ion content measuring apparatus as a third embodiment of the present invention.
FIG. 11 is an explanatory diagram showing an outline of surface potential measurement using the Kelvin method.
[Explanation of symbols]
100: Semiconductor wafer
100a ... surface
101 ... Semiconductor substrate (silicon substrate)
102 ... Insulating film (silicon oxide film)
110 ... Stepping motor
120: Piezoelectric actuator
130: Stand
140 ... Prism
140a ... bottom surface
150 ... Light emitting device
160. Light receiving element
170 ... Sample stage
190 ... Stage
190 ... Movement stage
201: Measuring electrode
300, 300a ... Light source device
302 ... Optical fiber
304 ... Lens
306 ... Chopper
306a ... axis
310 ... Z position control device
320: Light quantity measuring device
330 ... Capacity measuring instrument
340 ... SPV measuring instrument
350: Vibration capacitance potential measuring device
380 ... Stage control device
390 ... Host controller
392: In-membrane ion content determination unit
400: Corona charge generator
410: DC power supply
420 ... Ion ejection nozzle
422 ... Gas cylinder
424 ... Flow controller
426 ... Electrode for generating ions
MD1, MD2, MD3 ... Intramembrane ion content measuring device

Claims (10)

A method for measuring the amount of ions in a film existing in an insulating film formed on the surface of a semiconductor wafer using a measurement electrode,
(A) In an initial state in which the insulating film includes a plurality of types of in-film ions including first-type and second-type in-film ions, the semiconductor wafer is manufactured according to a predetermined measurement method using the measurement electrode. Measuring a first electrical characteristic value;
(B) by irradiation with light of the first Etsutsu given the electric field in the direction of the first wavelength range in said semiconductor wafer, a step of neutralizing the previous SL plurality of types of films in ions in the insulating film ,
(C) before SL state where a plurality of types of film within the ion is neutralized, measuring a second electrical characteristic value of the semiconductor wafer according to the predetermined measurement method,
; (D) from the first and second electrical characteristic values, and determining the amount of the initial state the insulating film layer before Symbol plurality of types that were present in the ions in,
(E) The first type of intra-film ions neutralized by irradiating the semiconductor wafer with light in a second wavelength range while applying an electric field in a second direction opposite to the first direction. Ionizing the same amount as the amount of ions in the first type of film that were present in the insulating film in the initial state;
(F) a step of measuring a third electrical characteristic value of the semiconductor wafer according to the predetermined measurement method in a state where the neutralized first type in-film ions are ionized in the step (e); ,
(G) determining the amount of the first type of in-film ions present in the insulating film in the initial state from the second and third electrical characteristic values;
(H) The second type neutralized by irradiating light in a third wavelength range having a shorter wavelength than the second wavelength range while applying an electric field in the second direction to the semiconductor wafer. Further ionizing in-film ions by an amount substantially equal to the amount of the second type of in-film ions present in the insulating film in the initial state;
(I) a step of measuring a fourth electrical characteristic value of the semiconductor wafer in accordance with the predetermined measurement method in a state where the neutralized second type in-film ions are further ionized in the step (h). When,
(J) From the first and fourth electrical characteristic values or the third and fourth electrical characteristic values, the second type of intra-film ions existing in the insulating film in the initial state Determining the amount of
A method for measuring the amount of ions in a membrane. A method for measuring the amount of ions in a film existing in an insulating film formed on the surface of a semiconductor wafer using a measurement electrode,
(A) In an initial state in which a plurality of types of in-film ions including first-type and second-type in-film ions are included in the insulating film, the first electric field is applied to the semiconductor wafer in a first direction. A step of neutralizing the plurality of types of ions in the insulating film by irradiating light in a wavelength range; and
(B) a step of measuring a first electrical characteristic value of the semiconductor wafer according to a predetermined measurement method using the measurement electrode in a state where the plurality of types of in-film ions are neutralized;
(C) The first type of intra-film ions neutralized by irradiating the semiconductor wafer with light in a second wavelength range while applying an electric field in a second direction opposite to the first direction. Ionizing the same amount as the amount of ions in the first type of film existing in the insulating film in the initial state;
(D) a step of measuring a second electrical characteristic value of the semiconductor wafer according to the predetermined measurement technique in a state where the neutralized first type in-film ions are ionized in the step (C); ,
(E) determining the amount of the first type of in-film ions present in the insulating film in the initial state from the first and second electrical characteristic values;
(F) Shorter than the second wavelength range while applying an electric field in the second direction to the semiconductor wafer. By irradiating light in the third wavelength range of the wavelength, the neutralized second-type in-film ions of the second-type in-film ions present in the insulating film in the initial state Further ionizing the same amount as the amount;
(G) A step of measuring a third electrical characteristic value of the semiconductor wafer according to the predetermined measurement method in a state where the neutralized second type in-film ions are further ionized in the step (F). When,
(H) determining the amount of the second type of in-film ions present in the insulating film in the initial state from the second and third electrical characteristic values;
A method for measuring the amount of ions in a membrane. A method for measuring the amount of ions in a membrane according to claim 1 or 2 ,
The light in the first wavelength range is
When the insulating film is a silicon oxide film, the in-film ion amount measuring method is light in at least a part of a range from about 220 nm to about 295 nm. A method for measuring the amount of ions in a membrane according to any one of claims 1 to 3 ,
The predetermined measurement method is a method for measuring the amount of ions in a membrane, which is CV measurement. A method for measuring the amount of ions in a membrane according to claim 4 ,
The CV measurement is an in-film ion content measurement method, which is a non-contact measurement in which the measurement electrode is not brought into contact with the insulating film. A method for measuring the amount of ions in a membrane according to any one of claims 1 to 3 ,
The predetermined measurement method is an in-film ion content measurement method using surface photovoltage measurement for measuring a surface photovoltage of the semiconductor wafer generated by irradiating the semiconductor wafer with intermittent light. A method for measuring the amount of ions in a membrane according to any one of claims 1 to 3 ,
The predetermined measurement method is an in-film ion content measurement method that uses vibration capacitance potential measurement that measures the surface potential of the semiconductor wafer while temporally changing the gap between the measurement electrode and the semiconductor wafer. A method for measuring the amount of ions in a membrane according to claim 7 ,
The in-film ion content measuring method, wherein the neutralizing step includes a step of applying an electric field to the semiconductor wafer by charging the surface of the insulating film. A device for measuring the amount of ions in a film that measures the amount of ions in a film existing in an insulating film formed on the surface of a semiconductor wafer,
  An electrical property measurement unit for measuring electrical property values of the semiconductor wafer according to a predetermined measurement technique using a measurement electrode;
  An electric field application / light irradiation unit for irradiating light while applying an electric field to the semiconductor wafer, wherein the insulating film includes a plurality of types of in-film ions including first-type and second-type in-film ions. By irradiating light in a first wavelength range while applying an electric field in a first direction to the semiconductor wafer in a state, the first state in which the plurality of types of ions in the insulating film are neutralized is obtained. Forming and neutralizing the first type of in-film ions by irradiating the semiconductor wafer with light in a second wavelength range while applying an electric field in a second direction opposite to the first direction. Forms a second state that is ionized by approximately the same amount as the amount of ions of the first type in the film existing in the insulating film in the initial state, and applies the second electric field to the semiconductor wafer. A third wavelength shorter than the second wavelength range. By irradiating light in a long range, the amount of the second type of in-film ions neutralized is approximately the same as the amount of the second type of in-film ions present in the insulating film in the initial state. Forming the third state that is further ionized, and the electric field application / light irradiation unit,
With
  The electrical property measuring unit is
  From the first electrical characteristic value of the semiconductor wafer measured in the initial state and the second electrical characteristic value of the semiconductor wafer measured in the first state, The amount of the plurality of types of ions in the film that were present in the second, and from the second electrical characteristic value and the third electrical characteristic value of the semiconductor wafer measured in the second state, The amount of the first type of in-film ions present in the insulating film in the initial state is determined, and the first electrical characteristic value and the first state of the semiconductor wafer measured in the third state are determined. 4 or the third electrical characteristic value and the fourth electrical characteristic value, the amount of ions in the second type of film existing in the insulating film in the initial state is determined. It is characterized by having an in-film ion content determination unit to determine Membrane in the ion measuring device. A device for measuring the amount of ions in a film that measures the amount of ions in a film existing in an insulating film formed on the surface of a semiconductor wafer,
  An electrical property measurement unit for measuring electrical property values of the semiconductor wafer according to a predetermined measurement technique using a measurement electrode;
  An electric field application / light irradiation unit for irradiating light while applying an electric field to the semiconductor wafer, wherein the insulating film includes a plurality of types of in-film ions including first-type and second-type in-film ions. By irradiating light in a first wavelength range while applying an electric field in a first direction to the semiconductor wafer in a state, the first state in which the plurality of types of ions in the insulating film are neutralized is obtained. Forming and neutralizing the first type of in-film ions by irradiating the semiconductor wafer with light in a second wavelength range while applying an electric field in a second direction opposite to the first direction. Forms a second state that is ionized by approximately the same amount as the amount of ions of the first type in the film existing in the insulating film in the initial state, and applies the second electric field to the semiconductor wafer. While providing a third wavelength shorter than the second wavelength range. By irradiating light in a long range, the amount of the second type of in-film ions neutralized is approximately the same as the amount of the second type of in-film ions present in the insulating film in the initial state. Forming the third state, which is further ionized, and the electric field application / light irradiation unit,
With
  The electrical property measuring unit is
  From the first electrical property value of the semiconductor wafer measured in the first state and the second electrical property value of the semiconductor wafer measured in the second state, the insulation in the initial state The amount of the first-type ions in the film existing in the film is determined, and the second electric characteristic value and the third electric characteristic value of the semiconductor wafer measured in the third state are determined. And an in-film ion amount determination unit that determines the amount of the second type of in-film ions present in the insulating film in the initial state.

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