JP2004140320A

JP2004140320A - Chemical vapor deposition equipment

Info

Publication number: JP2004140320A
Application number: JP2003114303A
Authority: JP
Inventors: Akinori Shimizu; 清水　了典
Original assignee: Fuji Electric Holdings Ltd
Current assignee: Fuji Electric Co Ltd
Priority date: 2002-08-23
Filing date: 2003-04-18
Publication date: 2004-05-13

Abstract

【課題】ウェハ面上に形成する薄膜の膜厚をばらつきを抑えて成膜できる化学的気相成長装置を提供すること。
【解決手段】化学的気相成長装置は、一端（上部）が閉じている外部容器管５と、この外部容器管５内に設置される反応室９となる内部容器管４と、この内部容器管４に収納されるボートと称せられる支持治具２と、外部容器管５を収納し、支持治具２にセットされたウェハ１を加熱するヒータ６を有する電気炉７などから構成され、この内部容器管４の内壁に、排気開口３が複数個設けられている。この排気開口３でラジカルなガスを排気して、厚さばらつきの少ない薄膜をウェハ１に成膜できる。
【選択図】　　　　図１An object of the present invention is to provide a chemical vapor deposition apparatus capable of forming a thin film formed on a wafer surface while suppressing variation in film thickness.
Kind Code: A1 Abstract: A chemical vapor deposition apparatus comprises: an outer container tube 5 having one end (upper portion) closed; an inner container tube 4 serving as a reaction chamber 9 installed in the outer container tube 5; A support jig 2 called a boat accommodated in the tube 4 and an electric furnace 7 having a heater 6 for accommodating the external container tube 5 and heating the wafer 1 set in the support jig 2 are provided. A plurality of exhaust openings 3 are provided on the inner wall of the inner container tube 4. By exhausting the radical gas through the exhaust opening 3, a thin film having a small thickness variation can be formed on the wafer 1.
[Selection diagram] Fig. 1

Description

【０００１】
【発明の属する技術分野】
この発明は、基板の表面に薄膜を形成する化学的気相成長装置に関する。
【０００２】
【従来の技術】
半導体デバイスは、半導体基板に多結晶シリコン膜、金属膜および絶縁膜など各種薄膜を積層して形成されるが、その成膜方法として化学的気相成長法が多用されている。
図１０は、従来のバッチ式の化学的気相成長装置の要部構成図であり、同図（ａ）は全体図、同図（ｂ）はウェハをセットした支持治具（ボート）の斜視図である。
化学的気相成長装置（ＣＶＤ装置：Ｃｈｅｍｉｃａｌ　Ｖａｐｏｒ　Ｄｅｐｏｓｉｔｉｏｎ装置）は、一端（上部）が閉じている外部容器管５と、この外部容器管５内に設置される、内部が反応室９となる内部容器管４と、この内部容器管４に収納されるボートと称せられる支持治具２と、外部容器管５を収納し、支持治具２にセットされたウェハ１（基板）を加熱するヒータ６を有する加熱炉７などから構成されている。また、支持治具２は、支持台２４と、この支持台２４にウェハ１を矢印Ｈの方向からセットできるように配置された複数本の支柱２５とこれらの支柱２５を途中で支える支え板２６で構成される。
【０００３】
支持治具２にウェハ１を多数枚、狭間隔で列状に配置し、この支持治具２を内部容器管４内に挿入し、外部容器管５の開口部（下部）に蓋８をして、密封し、外部容器管５内を減圧雰囲気にして、反応性ガスとキャリアガスを、下部に設置されているガス流入口１０から内部容器管４（反応室９）に導入し、上部に流れて来たこれらのガス流１２を内部容器管４の壁面と外部容器管５の壁面で挟まれた隙間を通して、ガス排気口１１から、図示しない真空ポンプで吸引して排気する。
図１０においては、下方から上方にガス流１２が流れるので、下方が源流領域２１となり、上方が下流領域２３となり、中間が中流領域２２となる。
【０００４】
この成膜方法は、ナノメートルオーダーの薄膜を比較的低温で制御性よく成長させることができる、優れた方法である。例えば、ＭＯＳ型トランジスタのゲート電極の材料として適用される多結晶シリコン膜（ポリシリコン膜）は、炉内温度５５０℃、真空度１００Ｐａの雰囲気中に、モノシラン（ＳｉＨ_４　）ガスを１０００ｓｃｃｍ、キャリアガスとして窒素（Ｎ_２）ガス２００ｓｃｃｍとともに注入すると約３０Å／分の成膜速度でウェハ１に堆積する。
上記の成膜速度下では、１枚ずつ処理する図示しない枚葉式の装置ではウェハ１上の膜厚の均一性は優れるが生産性を上げられないので、通常は５０枚から２００枚程度のウェハ１を同時に１回で処理するバッチ処理ができるバッチ式の装置が用いられる。このバッチ処理では、多数枚のウェハ１を、温度均一性の良い領域に配置するため、できるだけ小さな間隔でウェハ１を順次平行に並べ、その周辺部に反応性ガスをキャリアガスとともに流すという構成をとる。
【０００５】
このような構成において、膜厚分布が改善された化学的気相成長装置が、例えば、特許文献１に開示されている。図１１に示すように図１０で示した化学的気相成長装置の内部容器管４の内側に多数の孔の開いた内々管１５を設け、反応性ガスを内々管１５と内部容器管４の間に供給しガス流を内々管１５の複数の開口部よりウェハ間隔の内部に拡散させるものである（特許文献１）。
【０００６】
【特許文献１】
特開平３−２２５２２号公報
【０００７】
【発明が解決しようとする課題】
しかし、これらの構成では、反応性ガスは源流領域２１から下流領域２３へと高温雰囲気に触れながら流れるので、その間に熱エネルギーを受けて化学変化を起こし、当初の反応性ガス以外の反応種もわずかながらも混ざってくる。この反応種は極めて反応性に富む反応種（ラジカルな反応種）であり、ウェハ１に触れるとともにポリシリコン薄膜として堆積してしまうために、ウェハ１上の膜厚の均一性が充分とれないという問題が生じる。
図１２は、図１０に示す化学的気相成長装置の内部容器管内の様子を示すモデル図である。このモデル図を用いて膜厚が不均一になるメカニズムを説明する。
【０００８】
ポリシリコン成膜の場合、反応性ガスは１００％ＳｉＨ_４ガスで、キャリアガスであるＮ_２　ガスとともに反応室９である内部容器管４の下部から注入される。反応室９内ではウェハ設置領域にわたって５５０℃の均一温度に保たれており、その均一温度領域は１５０枚のバッチ装置では約８００ｍｍの長さがある。反応室９の下部から注入されたＳｉＨ_４ガス１３はこの長い高温領域で熱輻射やガス分子同士の衝突を受けて、以下の反応式に従って、一部はＳｉＨ_２ガス１４に変化する。
ＳｉＨ_４→　ＳｉＨ_２＋Ｈ_２
ここで、ＳｉＨ_２ガス１４は、ラジカルなガスと呼ばれ、極めて反応性に富み、ウェハ１の表面にぶつかるだけで分解してシリコン膜として堆積する。つまり、ＳｉＨ_２はラジカルな反応種である。
【０００９】
すなわち、ＳｉＨ_２ガス１４のＳｉＨ_４ガス１３に対する相対濃度が高くなればなるほど、ウェハ１の外周部でＳｉＨ_２ガス１４からのポリシリコンの堆積が盛んになり、その部分での膜厚が増加し、結果としてウェハ１面内の膜厚が不均一になる。
実際、ＳｉＨ_２のＳｉＨ_４に対する相対濃度（濃度割合）を求めると、源流領域２１にあるウェハでは１×１０^−７程度以下であるのに対し、中流領域２２にあるウェハでは３×１０^−７程度、下流領域２３にあるウェハでは７×１０^−７程度と増加する。そのために、下流領域２３の方が源流領域２１より膜厚のばらつきが大きくなる。つまり、ウェハ面内の膜厚の不均一性は、熱エネルギーにより生成されるＳｉＨ_２ガス１４の量に依存する。
【００１０】
図１３は、ウェハ位置と膜厚の関係を示す図である。全体で１５０枚のウェハ１を支持治具２にセットし、反応性ガスが流入する側を源流領域２１、中間を中流領域２２、反応性ガスが流出する側を下流領域２３の３領域に分割し、各領域に５０枚のウェハをセットしてウェハ１上にポリシリコン膜を成膜する。このときの狭間隔は８ｍｍである。成膜したポリシリコン膜の膜厚を、ウェハ１の中心を含む直線上の２０点（−４０ｍｍから＋４０ｍｍの間は１０ｍｍ間隔、その外側では５ｍｍ間隔である）で、図１４のＸ方向で測定する。この膜厚の測定は、源流領域２１、中流領域２２、下流領域２３の３領域にセットされた各５０枚のウェハで行う。つぎに、各領域のウェハ１の同一測定点での膜厚の平均値（５０枚の平均値）を出し、この平均値を、ウェハ１の中心での膜厚の平均値（５０枚の平均値）で割った値を、各測定点で、各領域での規格化した膜厚の平均値（以下、規格化平均膜厚値という）として示した。図中のＧは源流領域、Ｈは中流領域、Ｉは上流領域の各測定点での規格化平均膜厚値である。
【００１１】
前記したように、下流領域２３の方が、反応性に富んだ反応種の割合が多くなるために、下流領域２３で形成されるポリシリコン膜の規格化平均膜厚値のばらつきが１．５％と最大となり、源流領域２１でも０．８％と大きなばらつきとなる。
このようなことは、図１１においても同様にいえることである。
このように、ウェハ面内での薄膜の膜厚のばらつきが大きくなる場合の不都合について、薄膜としてポリシリコン膜を例に説明する。
図１５は、トレンチ溝の場合の不都合を説明する図である。トレンチゲートのＭＯＳＦＥＴなどのゲート電極を形成する場合、ゲート絶縁膜５２で被覆されたトレンチ溝５３をポリシリコン膜５１で充填して形成するが、ラジカルな反応種（ＳｉＨ_２　）があると、トレンチ溝５３が上部で塞がれて、トレンチ溝５３内部に空洞５４ができて、ゲート抵抗が増大する不具合を生じる。尚、図中の５５はウェル領域で、５６はソース領域である。
【００１２】
図１６は、プレーナの場合の不都合を説明する図である。プレーナ型の縦型のＭＯＳＦＥＴ（ＤＭＯＳ）などで、ゲート電極となるポリシリコン膜６１の膜厚にばらつきがあると、ポリシリコン膜６１をマスクとして、ウェル領域６２の表面層にソース領域６３を形成する場合に、薄い箇所（図では左側）では、ポリシリコン膜６１をイオン注入不純物６４が貫通して、チャネル部をドーピングして、しきい値電圧を変化させるという不都合が生じる。
このように、ウェハ１上に形成されるポリシリコン膜などの薄膜の膜厚がばらつくと半導体装置を製作する上で、前記したような不都合が生じる。
【００１３】
この発明の目的は、前記の課題を解決して、ウェハ面上に形成する薄膜の膜厚を均一にできる化学的気相成長装置を提供することにある。
【００１４】
【課題を解決するための手段】
前記の目的を達成するために、加熱炉と、該加熱炉に収納され、一端が閉じている外部容器管と、該外部容器管に収納され、両端が開口している内部容器管と、該内部容器管に収納され、複数の基板を列状に配置する支持治具とを具備し、内部容器管の壁面と、前記基板を配置した支持治具との間に反応性ガスを流して前記基板上に薄膜を形成する化学的気相成長装置において、内部容器管の壁面に前記反応性ガスの一部を排気する排気開口を有するものとする。
または、前記内部容器管は多重に形成され、少なくとも最も内側の内部容器管の壁面に前記反応性ガスの一部を排気する排気開口を有するものとする。
【００１５】
また、前記排気開口が、水平方向で前記内部容器管の中心に対称に形成されたものとする。
また、前記内部容器管の壁面がメッシュ状に形成された複数の前記排気開口を有するものとする。
または、前記内部容器管が基板の列方向で複数の領域に分けられ、各内部容器管に反応性ガスの内部供給口および内部排気口を備えているものとする。
前記支持治具に遮蔽板を備え、この遮蔽板により内部容器管内を複数の領域に分けるものとする。
【００１６】
前記内部容器管の複数の領域それぞれに供給される反応性ガスの反応性ガス供給管を備え、該反応性ガス供給管の前記外部容器管から前記内部容器管までの距離がほぼ等しいものとする。
前記内部容器管に前記反応性ガスを供給する反応性ガス供給管を備え、該反応性ガス供給管は前記内部容器管の各領域にほぼ水平方向の前記加熱炉の外部から前記外部容器管を介して前記内部容器管に達するものとする。
または、前記反応性ガスを外部容器管内の雰囲気温度と同程度の温度とする温度調節手段を有するものとする。
【００１７】
また、前記内部容器管に反応性ガスを供給するための反応性ガス供給管の内径を５０ｍｍ以下にするものとする。
ここで、反応性ガスを外部容器管内の雰囲気温度と同程度まで予め昇温する目的は、内部容器管を複数個に分け反応室が短くなったため、室温の反応性ガスを直接反応性室内に供給すると反応室内の温度分布が大きくなってしまい、薄膜の成長速度に分布が生じてしまうからである。また、反応性ガス供給管の内径を５０ｍｍ以下にするのは、反応性ガス供給管を高温に保つとその中でラジカルな反応種が生成するため、このままでは却って反応室内での薄膜ばらつきが大きくなってしまう。ラジカルな反応種の拡散距離は反応温度領域で２５ｍｍであることから、反応性ガス供給管の内径を５０ｍｍ以下にすることにより反応性ガス供給管の中で発生したラジカルな反応種を反応性ガス供給管の内壁に付着させ、消滅させることができるのである。
【００１８】
このように、バッチ式の化学的気相成長装置において、この装置の反応室となる内部容器管の壁面と基板列との間の空間（ガス流路になる）において熱エネルギーで生成されるＳｉＨ_２が、基板表面に侵入する確率を低下させることでウェハ１上の薄膜の膜厚均一性を向上させることができる。
【００１９】
【発明の実施の形態】
図１は、この発明の第１実施例の化学的気相成長装置の要部構成図で、図１０と同一箇所には同一符号を記した。図２は、図１の内部容器管の斜視図である。この実施例は、内部が反応室９となる内部容器管４の壁面に排気開口３を設けた例であり、ウェハ１にポリシリコン膜を堆積する場合を示した例である。
化学的気相成長装置は、一端（上部）が閉じている外部容器管５と、この外部容器管５内に設置される反応室９となる排気開口３を有する内部容器管４と、この内部容器管４に収納されるボートと称せられる支持治具２（図１０（ｂ）に示す）と、外部容器管５を収納し、支持治具２にセットされたウェハ１（基板）を加熱するヒータ６を有する加熱炉７などから構成されている。内部容器管４には、図２に示すような排気開口３が形成されており、この排気開口３から反応性ガスの一部を排気する。前記したラジカルな反応種は、下流領域に行くに従って増加するため、よりばらつきを抑えて成膜するためには、ガス流の方向に対して均一に反応性ガスの一部を排気する必要がある。よって、排気開口３は、水平方向に内部容器管の中心に対称に形成されている。さらには、水平方向において所定の間隔を有する複数の排気開口３を形成するのがよい。この実施例では、ガス流方向に１００ｍｍ間隔ごとに８個の排気開口を均等の間隔で形成した。
【００２０】
ポリシリコン膜の成膜においては、従来技術で示した条件と同条件で形成した。支持治具２にウェハ１を多数枚、列状に配置し、この支持治具２を内部容器管４内に挿入し、外部容器管５の開口部（下部）に蓋８をして、密封し、外部容器管５内を減圧雰囲気にして、反応性ガスであるＳｉＨ_４ガスとキャリアガスであるＮ_２ガスを、下部に設置されているガス流入口１０から内部容器管４（反応室９）に導入し、上部に流れて来たガス流および排気開口３から流れて来たガス流を、内部容器管４の壁面と外部容器管５の壁面で挟まれた隙間を通して、ガス排気口１１から図示しない真空ポンプで吸引して排気する。図においては、下方から上方にガス流が流れるので、下方が源流領域２１となり、上方が下流領域２３で、中間が中流領域２２となる。
【００２１】
図３は、図１に示す化学的気相成長装置の内部容器管内の様子を示すモデル図である。ガス流１２は、源流側から下流側へ流れる。前記の排気開口３は、水平方向において内部容器管５の中心に対称に形成されている。内部容器管５に排気開口３を設けることにより、内部容器管の壁面からＳｉＨ_４ガスの一部を排気し、それとともに内部容器管の壁面と基板列との間の空間（ガス流路になる）において熱エネルギーにより生成されるラジカルな反応種も排気するため、当該ラジカルな反応種が基板の間隙に侵入する確率を低減することができ、その濃度が、ＳｉＨ_２ガス１４の濃度の上昇を抑制することで、ガス１３により、ウェハ１内でのポリシリコン膜の膜厚を均一化できる。
【００２２】
なお、ここでは薄膜として、ポリシリコン膜を挙げたが、窒化膜や酸化膜の場合も本発明のように、ラジカルな反応種が隣り合う基板の相対する面の間に侵入する確率を低下させるため、内部容器管５に排気開口３を形成することは有効であると推測される。
図４は、図１の化学的気相成長装置を用いてウェハにポリシリコン膜を成膜したときの、膜厚分布である。
全体で１５０枚のウェハ１を支持治具２にセットし、反応性ガスが流入する側を源流領域２１、中間を中流領域２２、反応性ガスが流出する側を下流領域２３の３領域に分割し、各領域に５０枚のウェハ１をセットしてウェハ１上に薄膜としてポリシリコン膜を成膜する。成膜したポリシリコン膜の膜厚を、図１４に示すようにウェハ１の中心を含む直線上の２０点（−４０ｍｍから＋４０ｍｍの間は１０ｍｍ間隔、その外側では５ｍｍ間隔である）で測定する。
【００２３】
この膜厚の測定は、源流領域２１、中流領域２２、下流領域２３の３領域にセットされた各５０枚のウェハで行う。つぎに、各領域の同一測定点での膜厚の平均値を出し、この平均値を、ウェハ１の中心の膜厚の平均値で割った値を、各測定点での各領域での規格化した膜厚の平均値（規格化平均膜厚値）として示した。図中のＡは源流領域、Ｂは中流領域、Ｃは下流領域の各測定点での規格化平均膜厚値である。
排気開口３よりラジカルな反応種が排気されるために、下流領域Ｃで形成されるポリシリコン膜の規格化平均膜厚値のばらつきは０．７％と小さくなる。しかも、図示しないが下流領域Ｃでの規格化した膜厚の最大値（規格化最大膜厚値）のばらつきも、この規格化平均膜厚値のばらつきの約１．４倍程度で、１％と小さなばらつきになる。
【００２４】
このように、排気開口３を設けることで、薄膜の膜厚を１％以下の面内ばらつきに抑え込むことができるようになり、デバイス特性の均一性を大きく伸ばすことができるようになる。
図５は、この発明の第２実施例の化学的気相成長装置の要部構成図である。
第１実施例と異なる点は、内部容器管４が２重に形成されている点である。
内側の内部容器管には、第１の実施例と同様に排気開口３が設けられており、この排気開口３からラジカルな反応種の排気を行う。
この装置内で発生するラジカルな反応種は、下流領域に行くに従って増加するので、下流領域に行くに従って排気能力を高めることが望まれる。内部容器管を２重管とし、内側に排気開口を形成し、内部容器管の上部に排気口を設けることで下流領域からの排気能力を高めることができる。この実施例では、上部の排気口が外部容器管に対向しているため、よりラジカルな反応種の排気能力を高めることができる。ここでは、内部容器管が２重の場合を示したが、３重以上であってももちろんかまわない。
【００２５】
図６は、この発明の第３実施例の化学的気相成長装置の内部容器管の要部拡大図である。排気開口３がメッシュ状に形成されたものである。このようにメッシュ状に形成しても、均一性を向上した成膜を行うことができる。
図７は、この発明の第４実施例の化学的気相成長装置の要部構成図であり、（ａ）は全体図、（ｂ）はウェハをセットした支持治具の斜視図であり、図１０と同一箇所には同一符号を記した。
この実施例は、内部容器管４が複数の領域４３，４４および４５に分けられた例であり、ウェハ１にポリシリコン膜を堆積する場合を示した例である。
【００２６】
化学的気相成長装置は、一端（上部）が閉じている外部容器管５と、この外部容器管５内に設置される反応室９となる内部容器管４と、遮蔽板２７を備え該遮蔽板２７により内部容器管４を３つの領域に分離する支持治具２と、外部容器管５を収納し支持治具２にセットされたウェハ１（基板）を加熱するヒータ６を有する加熱炉７と、内部容器管４の各領域に反応性ガスを供給する内径が４５ｍｍの反応性ガス供給管１６などから構成される。
内部容器管４は、各領域に反応性ガスの流し込み口である内部供給口４１と排気ガスの取り出し口である内部排気口４２を備えている。内部供給口４１は反応性ガス供給管１６とつながっており、反応性ガス供給管１６は石英からなり加熱炉７，外部容器管５および内部容器管４に形成した貫通口に挿入し、外部容器管５および内部容器管４とそれぞれ融着させる。
【００２７】
また、支持治具２は、支持台２４，支柱２５および遮蔽板２７とからなり、遮蔽板２７により分けられた領域にウェハ１を配置する。支持治具２に設けた遮蔽板２７により内部容器管４を複数に分けるものである。また、支持治具２を回転させながら薄膜の成膜を行うことができる。
内部容器管４の各領域４３，４４および４５は、遮蔽板２７と内部容器管４との間の隙間でつながっており完全に分離はされていないが、遮蔽板２７を備えることにより、ほとんどの反応性ガスが内部排気口４２から排気され、遮蔽板２７と内部容器管４の間の隙間を通って隣接する領域に反応性ガスが導入されることを抑制できる。
【００２８】
反応性ガスを外部容器管５内の雰囲気温度と同程度まで予め昇温する手段は、反応性ガス供給管１６を加熱する構成であればよく、本実施例では、加熱炉７のヒータ６が反応ガスを昇温する手段を兼ねている。
ポリシリコン膜の成膜においては、従来技術で示した条件と同条件で成膜した。
支持治具２にウェハ１を多数枚、列状に配置し、この支持治具２を内部容器管４内の領域に挿入し、外部容器管５の開口部（下部）に蓋８をして、密封し、該部容器管５を減圧雰囲気にして、反応性ガスであるＳｉＨ_４ガスとキャリアガスであるＮ_２ガスを、図示しないそれぞれのタンクから供給し混合した反応性ガスを反応性ガス供給管１６に導入し、内部容器管４の各領域４３，４４および４５に導入する。内部排気口４２から流れて来たガス流を、内部容器管の壁面と外部陽気管５の壁面で挟まれた隙間を通して、ガス排気口１１から図示しない真空ポンプで吸引して排気する。図においては下方から上方にガス流が流れるので、各領域４３，４４および４５それぞれにおいて、下方が源流領域２１となり、上方が下流領域２３で、中間が中流領域２２となる。
【００２９】
このような構成とすることにより、反応室９となる内部容器管４の壁面と基板列との間の空間（ガス流路になる）で熱エネルギーにより生成されるＳｉＨ_２を減らすことにより、基板の表面に侵入する確率を低下させることで、ウェハ１上の薄膜の膜厚均一性を向上させることができ、ウェハ１に堆積するポリシリコン膜の膜厚の面内ばらつきを従来の１／２程度に改善することができる。
図８は、図７の化学的気相成長装置を用いてウェハ１にポリシリコン膜を成膜したときの、膜厚分布である。
全体で１８０枚のウェハ１を３等分し、６０枚ずつを内部容器管４の各領域の支持治具２にセットし、各領域４３，４４および４５において反応性ガスが流入する側を源流領域、中間を中流領域、反応性ガスが流出する側を下流領域の３領域に分割し、ウェハ１上に薄膜としてポリシリコン膜を成膜する。成膜したポリシリコン膜の膜厚を、図１４に示すようにウェハ１の中心を含む直線上の２０点（−４０ｍｍから＋４０ｍｍの間は１０ｍｍ間隔、その外側では５ｍｍ間隔である）で測定する。
【００３０】
この膜厚の測定は、領域４５の源流領域２１、中流領域２２、下流領域２３の３領域にセットされた各２０枚のウェハで行った。
各領域の同一測定点での膜厚の平均値を出し、この平均値を、ウェハ１の中心の膜厚の平均値で割った値を、各測定点での各領域での規格化した膜厚の平均値（規格化平均膜厚値）として示した。図中のＤは源流領域、Ｅは中流領域、Ｆは下流領域の各測定点での規格化平均膜厚値である。
ラジカルな反応種がウェハ１上に侵入しにくくなるために、下流領域Ｆで形成されるポリシリコン膜の規格化平均膜厚値のばらつきは０．７％と小さくなる。しかも、図示しないが下流領域Ｆでの規格化した膜厚の最大値（規格化最大膜厚値）のばらつきも、この規格化平均膜厚値のばらつきの約１．２倍程度で、１％と小さなばらつきになる。
【００３１】
図９は、この発明の第５実施例の化学的気相成長装置の要部構成図である。図７と同一箇所には同一符号を記した。
この実施例は、第４実施例と同様に内部容器管４が複数の領域４３，４４および４５に分けられた例である。
第４実施例と異なる点は、反応ガス供給管１６が外部容器管５の下方から外部容器管５と内部容器管４の間を通って、内部容器管の各領域４３，４４および４５にそれぞれ接続されている点である。
第４実施例に比べ、外部容器管５内での反応性ガス供給管１６の長さが長くなるために、ラジカルな反応種の生成量が第４実施例に比べ多くなるが、反応性ガス供給管１６の中では反応性ガスの流速が大きいため反応性ガス供給管１６内での反応性ガスの滞留時間が短く、ラジカルな反応種の生成量が低く抑えられ、また、反応性ガス供給管１６の内径を５０ｍｍ以下とすることにより、ラジカルな反応種の捕獲も行うため、図１０のような従来技術に比べラジカルな反応種の生成量は低く抑えられる。さらに、内部容器管４は複数の領域に分かれているため、従来に比べ膜厚のばらつきが小さい薄膜を成膜することができる。
【００３２】
また、本実施例では、ウェハ１を支持治具２に配置された石英や炭化珪素からなる薄板１７の上に積載した。この場合、薄板１７は、ウェハ１と略相似形状に形成し、ウェハ１は薄板１７と互いの中心が合致するように積載することにより、薄板１７の外周部でラジカルな反応種を捕獲することができるためよりばらつきの少ない薄膜を生膜することができる。もちろん、第４実施例のように、支持治具２に直接ウェハ１を配置する構成としてもよい。逆に、上述した他の実施例において、薄板１７を配置する構成としてもよい。
【００３３】
【発明の効果】
この発明により、ラジカルな反応種を排気する排気開口を、反応室である内部容器管の壁面に形成すること、または、内部容器管を複数の領域に分け、各内部容器管に反応性ガスの流し込み口と排気ガスの取り出し口を備えることにより、基板に堆積する薄膜の膜厚均一性を改善することができる。
【図面の簡単な説明】
【図１】この発明の第１実施例の化学的気相成長装置の要部構成図
【図２】この発明の内部容器管の実施例の斜視図
【図３】内部容器管内の様子を示すモデル図
【図４】図１の化学的気相成長装置を用いてウェハにポリシリコン膜を成膜したときの膜厚分布図
【図５】この発明の第２実施例の化学的気相成長装置の要部構成図
【図６】この発明の第３実施例の化学的気相成長装置の内部容器管の要部拡大図
【図７】この発明の第４実施例の化学的気相成長装置の要部構成図
【図８】図７の化学的気相成長装置を用いてウェハにポリシリコン膜を成膜したときの膜厚分布図
【図９】この発明の第５実施例の化学的気相成長装置の要部構成図
【図１０】従来のバッチ式の化学的気相成長装置の要部構成図であり、（ａ）は全体図、（ｂ）はウェハをセットした支持治具の斜視図
【図１１】従来のバッチ式の化学的気相成長装置の要部構成図
【図１２】図１０の縦型ポリシリコン化学的気相成長装置の内部容器管内の様子を示すモデル図
【図１３】ウェハ位置と膜厚の関係を示す図
【図１４】ウェハ上のポリシリコン膜の膜厚を測定する箇所を示す図
【図１５】トレンチ溝の場合の不都合を示す図
【図１６】プレーナの場合の不都合を示す図
【符号の説明】
１　　ウェハ
２　　支持治具
３　　排気開口
４　　内部容器管
５　　外部容器管
６　　ヒータ
７　　加熱炉
８　　蓋
９　　反応室
１０　　ガス流入口
１１　　ガス排出口
１２　　ガス流[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a chemical vapor deposition apparatus for forming a thin film on a surface of a substrate.
[0002]
[Prior art]
A semiconductor device is formed by stacking various thin films such as a polycrystalline silicon film, a metal film, and an insulating film on a semiconductor substrate, and a chemical vapor deposition method is often used as a film forming method.
FIGS. 10A and 10B are main part configuration diagrams of a conventional batch type chemical vapor deposition apparatus. FIG. 10A is an overall view, and FIG. 10B is a perspective view of a support jig (boat) on which a wafer is set. FIG.
The chemical vapor deposition apparatus (CVD apparatus: Chemical Vapor Deposition apparatus) includes an outer container tube 5 having one end (upper part) closed, and an inside which is installed in the outer container tube 5 and has a reaction chamber 9 inside. A container 6, a supporting jig 2 called a boat accommodated in the inner container 4, and a heater 6 accommodating the outer container 5 and heating the wafer 1 (substrate) set in the supporting jig 2. And the like. The support jig 2 includes a support 24, a plurality of columns 25 arranged so that the wafer 1 can be set on the support 24 from the direction of arrow H, and a support plate 26 that supports these columns 25 in the middle. It consists of.
[0003]
A large number of wafers 1 are arranged on the support jig 2 in a row at a narrow interval. The support jig 2 is inserted into the inner container tube 4, and the opening 8 (lower portion) of the outer container tube 5 is covered with a lid 8. Then, the inside of the outer container tube 5 is brought into a reduced pressure atmosphere, and a reactive gas and a carrier gas are introduced into the inner container tube 4 (reaction chamber 9) from the gas inlet 10 provided at the lower portion, and the upper portion is introduced into the upper portion. These flowing gas flows 12 are sucked and exhausted from a gas exhaust port 11 by a vacuum pump (not shown) through a gap sandwiched between a wall surface of the inner container tube 4 and a wall surface of the outer container tube 5.
In FIG. 10, since the gas flow 12 flows from below to above, the lower part becomes the source flow area 21, the upper part becomes the downstream area 23, and the middle part becomes the middle flow area 22.
[0004]
This film forming method is an excellent method capable of growing a thin film on the order of nanometers at a relatively low temperature with good controllability. For example, a polycrystalline silicon film (polysilicon film) applied as a material for a gate electrode of a MOS transistor is formed by using monosilane (SiH) in an atmosphere at a furnace temperature of 550 ° C. and a degree of vacuum of 100 Pa.₄) 1000 sccm gas and nitrogen (N₂) When the gas is injected together with 200 sccm, the gas is deposited on the wafer 1 at a film forming rate of about 30 ° / min.
Under the above-described film forming speed, a single-wafer type apparatus (not shown) that processes one sheet at a time has excellent uniformity of the film thickness on the wafer 1 but cannot increase the productivity. A batch-type apparatus capable of performing batch processing for simultaneously processing the wafers 1 at a time is used. In this batch processing, in order to arrange a large number of wafers 1 in a region with good temperature uniformity, the wafers 1 are sequentially arranged in parallel at as small an interval as possible, and a reactive gas and a carrier gas are caused to flow around the periphery thereof. Take.
[0005]
In such a configuration, a chemical vapor deposition apparatus in which the film thickness distribution is improved is disclosed in, for example, Patent Document 1. As shown in FIG. 11, an inner tube 15 having a large number of holes is provided inside the inner container tube 4 of the chemical vapor deposition apparatus shown in FIG. The gas flow is supplied between the plurality of openings of the inner end pipe 15 and diffused into the space between the wafers (Patent Document 1).
[0006]
[Patent Document 1]
JP-A-3-22522
[0007]
[Problems to be solved by the invention]
However, in these configurations, the reactive gas flows from the source flow area 21 to the downstream area 23 while being in contact with the high-temperature atmosphere. It mixes a little. This reactive species is a reactive species (radical reactive species) having a very high reactivity. Since the reactive species touches the wafer 1 and is deposited as a polysilicon thin film, the uniformity of the film thickness on the wafer 1 is not sufficient. Problems arise.
FIG. 12 is a model diagram showing a state inside the inner container tube of the chemical vapor deposition apparatus shown in FIG. The mechanism by which the film thickness becomes non-uniform will be described using this model diagram.
[0008]
In the case of polysilicon film formation, the reactive gas is 100% SiH₄Gas, carrier gas N₂Injected together with the gas from the lower part of the inner vessel tube 4 which is the reaction chamber 9. In the reaction chamber 9, a uniform temperature of 550 ° C. is maintained over the wafer installation area, and the uniform temperature area has a length of about 800 mm in a batch apparatus of 150 sheets. SiH injected from the lower part of the reaction chamber 9₄The gas 13 is subjected to heat radiation and collision of gas molecules in this long high temperature region, and a part of the gas 13 is SiH according to the following reaction formula.₂It changes to gas 14.
SiH₄→ SiH₂+ H₂
Where SiH₂The gas 14 is called a radical gas, is extremely reactive, and is decomposed and deposited as a silicon film only by hitting the surface of the wafer 1. That is, SiH₂Is a radical reactive species.
[0009]
That is, SiH₂SiH of gas 14₄As the relative concentration with respect to the gas 13 increases, the SiH₂The deposition of polysilicon from the gas 14 becomes active, and the film thickness at that portion increases, and as a result, the film thickness on the surface of the wafer 1 becomes uneven.
In fact, SiH₂SiH₄The relative concentration (concentration ratio) with respect to is 1 × 10^-7On the other hand, for the wafer in the midstream region 22, 3 × 10^-7About 7 × 10 for the wafer in the downstream region 23^-7Degree and increase. For this reason, the variation in the film thickness in the downstream region 23 is larger than that in the source region 21. That is, the non-uniformity of the film thickness in the wafer surface is caused by the SiH generated by the thermal energy.₂It depends on the amount of gas 14.
[0010]
FIG. 13 is a diagram showing the relationship between the wafer position and the film thickness. A total of 150 wafers 1 are set on the support jig 2, and the side into which the reactive gas flows is divided into the source flow area 21, the middle area into the middle flow area 22, and the side from which the reactive gas flows out into the downstream area 23. Then, 50 wafers are set in each area, and a polysilicon film is formed on the wafer 1. The narrow interval at this time is 8 mm. The thickness of the formed polysilicon film is measured in the X direction of FIG. 14 at 20 points on a straight line including the center of the wafer 1 (10 mm intervals between -40 mm and +40 mm, and 5 mm intervals outside thereof). I do. The measurement of the film thickness is performed on each of 50 wafers set in the three regions of the source flow region 21, the middle flow region 22, and the downstream region 23. Next, the average value of the film thickness at the same measurement point of the wafer 1 in each region (average value of 50 wafers) is obtained, and this average value is calculated as the average value of the film thickness at the center of the wafer 1 (average of 50 wafers). At each measurement point was shown as an average value of the normalized film thickness in each region (hereinafter, referred to as a normalized average film thickness value). In the figure, G is a head flow region, H is a middle flow region, and I is a normalized average film thickness value at each measurement point in an upstream region.
[0011]
As described above, in the downstream region 23, the ratio of the reactive species having high reactivity is higher, so that the variation in the normalized average film thickness value of the polysilicon film formed in the downstream region 23 is 1.5%. %, And the variation is as large as 0.8% even in the head flow region 21.
Such a thing can be said similarly in FIG.
The inconvenience in the case where the variation in the thickness of the thin film in the wafer surface becomes large as described above will be described using a polysilicon film as an example of the thin film.
FIG. 15 is a diagram for explaining inconvenience in the case of a trench groove. When a gate electrode such as a MOSFET of a trench gate is formed, a trench groove 53 covered with a gate insulating film 52 is formed by filling the polysilicon film 51 with a radical reactive species (SiH₂In the case of (ii), the trench groove 53 is closed at the upper portion, and a cavity 54 is formed inside the trench groove 53, which causes a problem that the gate resistance increases. Incidentally, 55 in the figure is a well region, and 56 is a source region.
[0012]
FIG. 16 is a diagram for explaining inconvenience in the case of a planar. If the thickness of the polysilicon film 61 serving as a gate electrode varies with a planar type vertical MOSFET (DMOS) or the like, a source region 63 is formed in the surface layer of the well region 62 using the polysilicon film 61 as a mask. In this case, at a thin portion (left side in the figure), there arises a problem that the ion implantation impurity 64 penetrates the polysilicon film 61 to dope the channel portion to change the threshold voltage.
As described above, if the thickness of the thin film such as the polysilicon film formed on the wafer 1 varies, the above-described inconvenience occurs in manufacturing the semiconductor device.
[0013]
An object of the present invention is to solve the above-mentioned problems and to provide a chemical vapor deposition apparatus capable of making the thickness of a thin film formed on a wafer surface uniform.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, a heating furnace, an outer container tube housed in the heating furnace, one end of which is closed, an inner container tube housed in the outer container tube, and open at both ends, A support jig accommodated in the inner container tube and arranging a plurality of substrates in a row is provided, and a reactive gas flows between the wall surface of the inner container tube and the support jig where the substrate is arranged. In a chemical vapor deposition apparatus for forming a thin film on a substrate, an exhaust opening for exhausting a part of the reactive gas is provided on a wall surface of an inner container tube.
Alternatively, the inner container pipe may be formed in multiple layers, and may have an exhaust opening for exhausting a part of the reactive gas on at least a wall surface of the innermost inner container pipe.
[0015]
Further, it is assumed that the exhaust opening is formed symmetrically at the center of the inner container tube in the horizontal direction.
Further, it is assumed that the inner container pipe has a plurality of exhaust openings in which a wall surface is formed in a mesh shape.
Alternatively, the inner container tube is divided into a plurality of regions in the row direction of the substrate, and each inner container tube has an internal supply port and an internal exhaust port for the reactive gas.
The support jig is provided with a shielding plate, and the inside of the inner container tube is divided into a plurality of regions by the shielding plate.
[0016]
A reactive gas supply pipe for a reactive gas supplied to each of the plurality of regions of the inner container pipe is provided, and the distances of the reactive gas supply pipes from the outer container pipe to the inner container pipe are substantially equal. .
A reactive gas supply pipe for supplying the reactive gas to the inner container pipe, wherein the reactive gas supply pipe connects the outer container pipe from the outside of the heating furnace in a substantially horizontal direction to each region of the inner container pipe. Through the inner container tube.
Alternatively, a temperature adjusting means for adjusting the temperature of the reactive gas to about the same as the ambient temperature in the outer container tube is provided.
[0017]
Further, the inner diameter of the reactive gas supply pipe for supplying the reactive gas to the inner container pipe is set to 50 mm or less.
Here, the purpose of preliminarily raising the temperature of the reactive gas to about the same as the ambient temperature in the outer vessel tube is to divide the inner vessel pipe into a plurality of sections and shorten the reaction chamber. This is because, if supplied, the temperature distribution in the reaction chamber becomes large, and a distribution occurs in the growth rate of the thin film. In addition, the reason why the inner diameter of the reactive gas supply pipe is set to 50 mm or less is that when the reactive gas supply pipe is kept at a high temperature, radical reactive species are generated therein, and if it is left as it is, the variation in the thin film in the reaction chamber becomes large. turn into. Since the diffusion distance of the radical reactive species is 25 mm in the reaction temperature range, by setting the inner diameter of the reactive gas supply pipe to 50 mm or less, the reactive species generated in the reactive gas supply pipe can be reacted with the reactive gas. It can adhere to the inner wall of the supply pipe and be extinguished.
[0018]
As described above, in a batch type chemical vapor deposition apparatus, SiH generated by thermal energy in a space (a gas flow path) between a wall surface of an inner vessel tube serving as a reaction chamber of the apparatus and a substrate row.₂However, the uniformity of the thin film on the wafer 1 can be improved by reducing the probability of intrusion into the substrate surface.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a configuration diagram of a main part of a chemical vapor deposition apparatus according to a first embodiment of the present invention. In FIG. FIG. 2 is a perspective view of the inner container tube of FIG. This embodiment is an example in which the exhaust opening 3 is provided on the wall surface of the inner container tube 4 in which the inside becomes the reaction chamber 9, and is an example showing a case where a polysilicon film is deposited on the wafer 1.
The chemical vapor deposition apparatus includes an outer container tube 5 having one end (upper part) closed, an inner container tube 4 having an exhaust opening 3 serving as a reaction chamber 9 installed in the outer container tube 5, A support jig 2 (shown in FIG. 10B) called a boat accommodated in the container tube 4 and an external container tube 5 are accommodated, and the wafer 1 (substrate) set in the support jig 2 is heated. It comprises a heating furnace 7 having a heater 6 and the like. An exhaust opening 3 as shown in FIG. 2 is formed in the inner container tube 4, and a part of the reactive gas is exhausted from the exhaust opening 3. Since the above-mentioned radical reactive species increases toward the downstream region, it is necessary to exhaust a part of the reactive gas uniformly in the direction of the gas flow in order to form a film with less variation. . Therefore, the exhaust opening 3 is formed symmetrically with respect to the center of the inner container tube in the horizontal direction. Further, it is preferable to form a plurality of exhaust openings 3 having a predetermined interval in the horizontal direction. In this embodiment, eight exhaust openings are formed at equal intervals in the gas flow direction at intervals of 100 mm.
[0020]
The polysilicon film was formed under the same conditions as those shown in the prior art. A large number of wafers 1 are arranged in a row on the support jig 2, the support jig 2 is inserted into the inner container tube 4, the opening 8 (lower portion) of the outer container tube 5 is covered with a lid 8, and sealed. Then, the inside of the outer container tube 5 is set to a reduced pressure atmosphere, and the reactive gas SiH₄Gas and N as carrier gas₂The gas is introduced into the inner vessel tube 4 (reaction chamber 9) from the gas inlet 10 provided at the lower part, and the gas flow flowing from the upper part and the gas flow flowing from the exhaust opening 3 are converted into the inner vessel. The gas is sucked and exhausted from the gas exhaust port 11 by a vacuum pump (not shown) through a gap sandwiched between the wall surface of the pipe 4 and the wall surface of the outer container pipe 5. In the figure, since the gas flow flows from below to above, the lower part becomes the source flow area 21, the upper part becomes the downstream area 23, and the middle part becomes the middle flow area 22.
[0021]
FIG. 3 is a model diagram showing a state inside the inner vessel tube of the chemical vapor deposition apparatus shown in FIG. The gas flow 12 flows from the source flow side to the downstream side. The exhaust opening 3 is formed symmetrically with respect to the center of the inner container tube 5 in the horizontal direction. By providing the exhaust opening 3 in the inner container tube 5, SiH₄Part of the gas is exhausted, and at the same time, the radical reaction species generated by thermal energy in the space between the wall surface of the inner container tube and the substrate row (which becomes a gas flow path) is also exhausted. The probability of species invading the substrate gap can be reduced, and the₂By suppressing the increase in the concentration of the gas 14, the gas 13 can make the thickness of the polysilicon film in the wafer 1 uniform.
[0022]
Here, a polysilicon film is used as the thin film. However, in the case of a nitride film or an oxide film, as in the present invention, the probability of radical reactive species entering between opposing surfaces of adjacent substrates is reduced. Therefore, it is presumed that forming the exhaust opening 3 in the inner container tube 5 is effective.
FIG. 4 is a film thickness distribution when a polysilicon film is formed on a wafer using the chemical vapor deposition apparatus of FIG.
A total of 150 wafers 1 are set on the support jig 2, and the side into which the reactive gas flows is divided into the source flow area 21, the middle area into the middle flow area 22, and the side from which the reactive gas flows out into the downstream area 23. Then, 50 wafers 1 are set in each area, and a polysilicon film is formed on the wafer 1 as a thin film. As shown in FIG. 14, the thickness of the formed polysilicon film is measured at 20 points on a straight line including the center of the wafer 1 (at intervals of 10 mm between -40 mm and +40 mm, and at intervals of 5 mm outside thereof). .
[0023]
The measurement of the film thickness is performed on each of 50 wafers set in the three regions of the source flow region 21, the middle flow region 22, and the downstream region 23. Next, the average value of the film thickness at the same measurement point in each area is obtained, and the average value is divided by the average value of the film thickness at the center of the wafer 1 to obtain a standard value in each area at each measurement point. The average value of normalized film thickness (normalized average film thickness value) was shown. In the figure, A is a source flow region, B is a middle flow region, and C is a normalized average film thickness value at each measurement point in a downstream region.
Since radical reactive species are exhausted from the exhaust opening 3, the variation in the normalized average film thickness of the polysilicon film formed in the downstream region C is as small as 0.7%. Further, although not shown, the variation of the maximum value of the normalized film thickness (normalized maximum film thickness value) in the downstream region C is also about 1.4 times the variation of the normalized average film thickness value, and is 1%. And small variations.
[0024]
By providing the exhaust opening 3 in this manner, the thickness of the thin film can be suppressed to an in-plane variation of 1% or less, and the uniformity of device characteristics can be greatly extended.
FIG. 5 is a configuration diagram of a main part of a chemical vapor deposition apparatus according to a second embodiment of the present invention.
The difference from the first embodiment is that the inner container tube 4 is formed in two layers.
As in the first embodiment, an exhaust opening 3 is provided in the inner internal vessel tube, and radical reactive species are exhausted from the exhaust opening 3.
Since the number of radical reactive species generated in the apparatus increases toward the downstream region, it is desired to increase the exhaust capacity as the region reaches the downstream region. By forming the inner container pipe as a double pipe, forming an exhaust opening inside, and providing an exhaust port at the upper portion of the inner container pipe, it is possible to increase the exhaust capacity from the downstream region. In this embodiment, since the upper exhaust port is opposed to the outer container tube, it is possible to increase the exhaust ability of more radical reactive species. Here, the case where the inner container pipe is double is shown, but it is needless to say that the inner container pipe may be triple or more.
[0025]
FIG. 6 is an enlarged view of a main part of an inner container tube of a chemical vapor deposition apparatus according to a third embodiment of the present invention. The exhaust opening 3 is formed in a mesh shape. Even if the film is formed in a mesh shape as described above, a film with improved uniformity can be formed.
FIGS. 7A and 7B are schematic diagrams of a main part of a chemical vapor deposition apparatus according to a fourth embodiment of the present invention. FIG. 7A is an overall view, FIG. 7B is a perspective view of a support jig on which a wafer is set, The same parts as those in FIG. 10 are denoted by the same reference numerals.
This embodiment is an example in which the inner container tube 4 is divided into a plurality of regions 43, 44 and 45, and is an example showing a case where a polysilicon film is deposited on the wafer 1.
[0026]
The chemical vapor deposition apparatus includes an outer container tube 5 having one end (upper portion) closed, an inner container tube 4 serving as a reaction chamber 9 installed in the outer container tube 5, and a shielding plate 27. A heating jig 7 having a supporting jig 2 for separating the inner container tube 4 into three regions by a plate 27 and a heater 6 for housing the outer container tube 5 and heating the wafer 1 (substrate) set in the supporting jig 2. And a reactive gas supply pipe 16 having an inner diameter of 45 mm for supplying a reactive gas to each region of the inner container tube 4.
The internal container pipe 4 has an internal supply port 41 as a flow port for a reactive gas and an internal exhaust port 42 as a discharge port for exhaust gas in each region. The internal supply port 41 is connected to the reactive gas supply pipe 16, and the reactive gas supply pipe 16 is made of quartz and inserted into the through holes formed in the heating furnace 7, the external vessel pipe 5 and the internal vessel pipe 4, and The tube 5 and the inner container tube 4 are each fused.
[0027]
The support jig 2 includes a support 24, a support 25, and a shielding plate 27, and arranges the wafer 1 in a region divided by the shielding plate 27. The inner container tube 4 is divided into a plurality of parts by a shielding plate 27 provided on the support jig 2. Further, a thin film can be formed while rotating the support jig 2.
The respective regions 43, 44 and 45 of the inner container tube 4 are connected by a gap between the shielding plate 27 and the inner container tube 4 and are not completely separated from each other. It is possible to suppress the reactive gas from being exhausted from the internal exhaust port 42 and from being introduced into the adjacent region through the gap between the shielding plate 27 and the internal container pipe 4.
[0028]
The means for previously raising the temperature of the reactive gas to about the same as the ambient temperature in the outer vessel tube 5 may be any configuration that heats the reactive gas supply pipe 16, and in this embodiment, the heater 6 of the heating furnace 7 is Also serves as a means for raising the temperature of the reaction gas.
In forming the polysilicon film, the film was formed under the same conditions as those described in the related art.
A large number of wafers 1 are arranged in a row on the support jig 2, the support jig 2 is inserted into a region inside the inner container tube 4, and the opening (lower portion) of the outer container tube 5 is covered with a lid 8. Then, the container tube 5 is set in a reduced pressure atmosphere, and the reactive gas SiH₄Gas and N as carrier gas₂The gas is supplied from respective tanks (not shown), and the mixed reactive gas is introduced into the reactive gas supply pipe 16 and introduced into the respective regions 43, 44 and 45 of the inner container pipe 4. The gas flow flowing from the internal exhaust port 42 is sucked and exhausted from the gas exhaust port 11 by a vacuum pump (not shown) through a gap between the wall surface of the inner container pipe and the wall surface of the external positive air pipe 5. In the figure, the gas flow flows from below to above, so that in each of the regions 43, 44 and 45, the lower portion is the source flow region 21, the upper portion is the downstream region 23, and the middle is the middle flow region 22.
[0029]
With such a configuration, SiH generated by thermal energy in a space (a gas flow path) between the wall surface of the inner vessel tube 4 serving as the reaction chamber 9 and the substrate row is formed.₂By reducing the probability of intrusion into the surface of the substrate, the uniformity of the thickness of the thin film on the wafer 1 can be improved, and the in-plane variation of the thickness of the polysilicon film deposited on the wafer 1 can be improved. Can be improved to about の of the related art.
FIG. 8 shows a film thickness distribution when a polysilicon film is formed on the wafer 1 using the chemical vapor deposition apparatus of FIG.
A total of 180 wafers 1 are divided into three equal parts, and 60 wafers are set on the support jig 2 in each region of the inner container tube 4. In each of the regions 43, 44 and 45, the source gas flows from the side where the reactive gas flows. The region, the middle region is a middle flow region, and the side from which the reactive gas flows out is divided into three regions: a downstream region, and a polysilicon film is formed on the wafer 1 as a thin film. As shown in FIG. 14, the thickness of the formed polysilicon film is measured at 20 points on a straight line including the center of the wafer 1 (at intervals of 10 mm between -40 mm and +40 mm, and at intervals of 5 mm outside thereof). .
[0030]
The measurement of the film thickness was performed on each of 20 wafers set in three regions of the source flow region 21, the middle flow region 22, and the downstream region 23 of the region 45.
The average value of the film thickness at the same measurement point in each region is obtained, and the average value is divided by the average value of the film thickness at the center of the wafer 1 to obtain a normalized film thickness in each region at each measurement point. It was shown as the average value of the thickness (normalized average film thickness). In the figure, D is a source flow region, E is a middle flow region, and F is a normalized average film thickness value at each measurement point in a downstream region.
Since it is difficult for radical reactive species to enter the wafer 1, the variation in the normalized average thickness of the polysilicon film formed in the downstream region F is as small as 0.7%. Further, although not shown, the variation of the maximum value of the normalized film thickness (normalized maximum film thickness value) in the downstream region F is about 1.2 times as large as the variation of the normalized average film thickness value, which is 1%. And small variations.
[0031]
FIG. 9 is a configuration diagram of a main part of a chemical vapor deposition apparatus according to a fifth embodiment of the present invention. The same parts as those in FIG. 7 are denoted by the same reference numerals.
This embodiment is an example in which the inner container tube 4 is divided into a plurality of regions 43, 44 and 45 as in the fourth embodiment.
The difference from the fourth embodiment is that the reaction gas supply pipe 16 passes between the outer vessel pipe 5 and the inner vessel pipe 4 from below the outer vessel pipe 5 and enters the respective regions 43, 44 and 45 of the inner vessel pipe. It is a connected point.
Since the length of the reactive gas supply pipe 16 in the outer vessel tube 5 is longer than in the fourth embodiment, the amount of radical reactive species generated is larger than in the fourth embodiment. Since the flow rate of the reactive gas in the supply pipe 16 is high, the residence time of the reactive gas in the reactive gas supply pipe 16 is short, and the amount of radical reactive species generated is suppressed to a low level. By setting the inner diameter of the tube 16 to 50 mm or less, radical reactive species are also captured, so that the amount of radical reactive species generated can be suppressed lower than in the conventional technique as shown in FIG. Further, since the inner container tube 4 is divided into a plurality of regions, it is possible to form a thin film having less variation in film thickness as compared with the related art.
[0032]
In this embodiment, the wafer 1 is mounted on the thin plate 17 made of quartz or silicon carbide placed on the support jig 2. In this case, the thin plate 17 is formed in a substantially similar shape to the wafer 1, and the wafer 1 is loaded so that the centers of the thin plate 17 and the thin plate 17 coincide with each other, so that radical reactive species can be captured at the outer peripheral portion of the thin plate 17. Therefore, a thin film having less variation can be formed. Needless to say, a configuration in which the wafer 1 is directly disposed on the support jig 2 as in the fourth embodiment may be adopted. Conversely, in the other embodiments described above, the configuration may be such that the thin plate 17 is arranged.
[0033]
【The invention's effect】
According to the present invention, an exhaust opening for exhausting radical reactive species can be formed in the wall surface of the inner container tube that is a reaction chamber, or the inner container tube is divided into a plurality of regions, and the reactive gas is supplied to each inner container tube. The provision of the inlet and the outlet of the exhaust gas can improve the uniformity of the thickness of the thin film deposited on the substrate.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a main part of a chemical vapor deposition apparatus according to a first embodiment of the present invention.
FIG. 2 is a perspective view of an embodiment of the inner container tube of the present invention.
FIG. 3 is a model diagram showing a state in an inner container tube.
FIG. 4 is a diagram showing a film thickness distribution when a polysilicon film is formed on a wafer using the chemical vapor deposition apparatus of FIG. 1;
FIG. 5 is a configuration diagram of a main part of a chemical vapor deposition apparatus according to a second embodiment of the present invention.
FIG. 6 is an enlarged view of a main part of an inner container tube of a chemical vapor deposition apparatus according to a third embodiment of the present invention.
FIG. 7 is a main part configuration diagram of a chemical vapor deposition apparatus according to a fourth embodiment of the present invention.
8 is a film thickness distribution diagram when a polysilicon film is formed on a wafer using the chemical vapor deposition apparatus of FIG. 7;
FIG. 9 is a configuration diagram of a main part of a chemical vapor deposition apparatus according to a fifth embodiment of the present invention.
10A and 10B are main-part configuration diagrams of a conventional batch-type chemical vapor deposition apparatus, where FIG. 10A is an overall view and FIG. 10B is a perspective view of a support jig on which a wafer is set.
FIG. 11 is a main part configuration diagram of a conventional batch type chemical vapor deposition apparatus.
12 is a model diagram showing a state inside an inner vessel tube of the vertical polysilicon chemical vapor deposition apparatus of FIG.
FIG. 13 is a diagram showing a relationship between a wafer position and a film thickness.
FIG. 14 is a diagram showing a portion where the thickness of a polysilicon film on a wafer is measured.
FIG. 15 is a diagram showing inconvenience in the case of a trench groove;
FIG. 16 is a diagram showing inconvenience in the case of a planar;
[Explanation of symbols]
1 wafer
2) Support jig
3 Exhaust opening
4 Inner container tube
5 Outer container tube
6 heater
7 heating furnace
8 lid
9 Reaction chamber
10mm gas inlet
11 Gas outlet
12 gas flow

Claims

A heating furnace, an outer container tube housed in the heating furnace, one end of which is closed; an inner container tube housed in the outer container tube, both ends of which are open; and a plurality of housed in the inner container tube, A supporting jig for arranging the substrates in a row, and forming a thin film on the substrate by flowing a reactive gas between the wall surface of the inner container tube and the supporting jig on which the substrate is arranged. In the vapor phase growth equipment,
A chemical vapor deposition apparatus having an exhaust opening for exhausting a part of the reactive gas on a wall surface of the inner vessel tube.

A heating furnace, an outer container tube housed in the heating furnace, one end of which is closed; an inner container tube housed in the outer container tube, both ends of which are open; and a plurality of housed in the inner container tube, A supporting jig for arranging the substrates in a row, and forming a thin film on the substrate by flowing a reactive gas between the wall surface of the inner container tube and the supporting jig on which the substrate is arranged. In the vapor phase growth equipment,
The chemical vapor deposition apparatus according to claim 1, wherein the inner container tube is formed in multiple layers, and has an exhaust opening for exhausting a part of the reactive gas at least on a wall surface of the innermost inner container tube.

3. The chemical vapor deposition apparatus according to claim 1, wherein the exhaust opening is formed symmetrically with respect to a center of the inner vessel tube in a horizontal direction.

The chemical vapor deposition apparatus according to claim 1, wherein a wall surface of the inner container tube has a plurality of the exhaust openings formed in a mesh shape.

A heating furnace, an outer container tube housed in the heating furnace, one end of which is closed; an inner container tube housed in the outer container tube, both ends of which are open; and a plurality of housed in the inner container tube, A supporting jig for arranging the substrates in a row, in a chemical vapor deposition apparatus for forming a thin film on the substrate by flowing a reactive gas to the inner container tube,
The chemical vapor deposition apparatus, wherein the inner container tube is divided into a plurality of regions in the row direction of the substrate, and each inner container tube has an internal supply port and an internal exhaust port for a reactive gas.

The said support jig is provided with the shielding board arrange | positioned between the said board | substrates arrange | positioned in a row, The said inner container pipe | tube is divided into several area | regions by the said shielding board, The Claims characterized by the above-mentioned. Chemical vapor deposition equipment.

A reactive gas supply pipe for a reactive gas supplied to each of the plurality of regions of the inner container pipe is provided, and the distance from the outer container pipe to the inner container pipe of the reactive gas supply pipe is substantially equal. 7. The chemical vapor deposition apparatus according to claim 5, wherein:

A reactive gas supply pipe for supplying the reactive gas to the inner container pipe, wherein the reactive gas supply pipe connects the outer container pipe from the outside of the heating furnace in a substantially horizontal direction to each region of the inner container pipe. The chemical vapor deposition apparatus according to claim 5, wherein the chemical vapor deposition apparatus is configured to reach the internal vessel tube via a through hole.

The chemical vapor deposition apparatus according to any one of claims 5 to 8, further comprising temperature control means for controlling the temperature of the reactive gas to be substantially the same as the ambient temperature in the outer vessel tube.

7. The reactive gas supply pipe for supplying a reactive gas to the inner container pipe, wherein the inner diameter of the reactive gas supply pipe is set to 50 mm or less. Chemical vapor deposition equipment.

10. The chemical vapor deposition apparatus according to claim 7, wherein an inner diameter of the reactive gas supply pipe is set to 50 mm or less.