JP3781730B2 - Method for forming silicon insulating film having low dielectric constant and high mechanical strength - Google Patents

Description

図２は、上記実験条件にてO₂の流量を０から２００sccmまで変化させた場合における誘電率及び膜硬度の関係を示したグラフである。グラフから上記実験条件においては、誘電率が２.８若しくはそれ以下で膜硬度が２.５GPa若しくはそれ以上となる絶縁膜を形成するための最適なO₂流量は５０から１５０sccmであることがわかる。
【００４７】
（実験２）
図１に示したプラズマCVD装置1を用いて、φ３００mmのシリコン基板上に絶縁膜を形成する実験を行った。

図３は、上記実験条件にてCO₂の流量を０から１０００sccmまで変化させた場合における誘電率及び膜硬度の関係を示したグラフである。グラフから上記実験条件においては、誘電率が２.８若しくはそれ以下で膜硬度が２.５GPa若しくはそれ以上となる絶縁膜を形成するための最適なCO₂流量は１００から９００sccmであることがわかる。
【００４８】
（実験３）
図１に示したプラズマCVD装置1を用いて、φ３００mmのシリコン基板上に絶縁膜を形成する実験を行った。

図４は、上記実験条件にて第２RF電源の電力密度を０から０.５ W/cm²まで変化させた場合における誘電率及び膜硬度の関係を示したグラフである。グラフから上記実験条件においては、誘電率が２.８若しくはそれ以下で膜硬度が２.５GPa若しくはそれ以上となる絶縁膜を形成するための最適な第２RF電源の電力密度は０.０２５から０.４ W/cm²であることがわかる。
【００４９】
（実験４）
図１に示したプラズマCVD装置1を用いて、φ３００mmのシリコン基板上に絶縁膜を形成する実験を行った。

図５は、上記実験条件にてエチレングリコールの流量を０から２００sccmまで変化させた場合における誘電率及び膜硬度の関係を示したグラフである。グラフから上記実験条件においては、誘電率が２.８若しくはそれ以下で膜硬度が２.５GPa若しくはそれ以上となる絶縁膜を形成するための最適なエチレングリコール流量は５０から１００sccmであることがわかる。
【００５０】
（実験５）
図１に示したプラズマCVD装置1を用いて、φ３００mmのシリコン基板上に絶縁膜を形成する実験を行った。

図６は、上記実験条件にてエチレングリコールの流量を０から２００sccmまで変化させた場合における誘電率及び膜硬度の関係を示したグラフである。グラフから上記実験条件においては、誘電率が２.８若しくはそれ以下で膜硬度が２.５GPa若しくはそれ以上となる絶縁膜を形成するための最適なエチレングリコール流量は１００から１５０sccmであることがわかる。
【００５１】
（実験６）
図１に示したプラズマCVD装置1を用いて、φ３００mmのシリコン基板上に絶縁膜を形成する実験を行った。

図７は、上記実験条件にて1,2プロパンジオールの流量を０から４００sccmまで変化させた場合における誘電率及び膜硬度の関係を示したグラフである。グラフから上記実験条件においては、誘電率が２.８若しくはそれ以下で膜硬度が２.５GPa若しくはそれ以上となる絶縁膜を形成するための最適な1,2プロパンジオール流量は５０から３００sccmであることがわかる。
【００５２】
（実験７）
図１に示したプラズマCVD装置1を用いて、φ３００mmのシリコン基板上に絶縁膜を形成する実験を行った。

図８は、上記実験条件にて1,2プロパンジオールの流量を０から４００sccmまで変化させた場合における誘電率及び膜硬度の関係を示したグラフである。グラフから上記実験条件においては、誘電率が２.８若しくはそれ以下で膜硬度が２.５GPa若しくはそれ以上となる絶縁膜を形成するための最適な1,2プロパンジオール流量は２００から３００sccmであることがわかる。
【００５３】
（実験８）
図１に示したプラズマCVD装置1を用いて、φ３００mmのシリコン基板上に絶縁膜を形成する実験を行った。

図９は、上記実験条件にてエチレンの流量を０から５００sccmまで変化させた場合における誘電率及び膜硬度の関係を示したグラフである。グラフから上記実験条件においては、誘電率が２.８若しくはそれ以下で膜硬度が２.５GPa若しくはそれ以上となる絶縁膜を形成するための最適なエチレン流量は５０から４５０sccmであることがわかる。
【００５４】
（実験９）
図１に示したプラズマCVD装置1を用いて、φ３００mmのシリコン基板上に絶縁膜を形成する実験を行った。

図１０は、上記実験条件にてエチレンの流量を０から５００sccmまで変化させた場合における誘電率及び膜硬度の関係を示したグラフである。グラフから上記実験条件においては、誘電率が２.８若しくはそれ以下で膜硬度が２.５GPa若しくはそれ以上となる絶縁膜を形成するための最適なエチレン流量は３００から４５０sccmであることがわかる。
【００５５】
（実験１０）
図１に示したプラズマCVD装置1を用いて、φ３００mmのシリコン基板上に絶縁膜を形成する実験を行った。

図１１は、上記実験条件にてN₂の流量を０から５００sccmまで変化させた場合における誘電率及び膜硬度の関係を示したグラフである。グラフから上記実験条件においては、誘電率が２.８若しくはそれ以下で膜硬度が２.５GPa若しくはそれ以上となる絶縁膜を形成するための最適なN₂流量は１００から４００sccmであることがわかる。
【００５６】
（実験１１）
図１に示したプラズマCVD装置1を用いて、φ３００mmのシリコン基板上に絶縁膜を形成する実験を行った。

図１２は、上記実験条件にてN₂の流量を０から５００sccmまで変化させた場合における誘電率及び膜硬度の関係を示したグラフである。グラフから上記実験条件においては、誘電率が２.８若しくはそれ以下で膜硬度が２.５GPa若しくはそれ以上となる絶縁膜を形成するための最適なN₂流量は２００から４００sccmであることがわかる。
【００５７】
（実験１２）
図１に示したプラズマCVD装置1を用いて、φ３００mmのシリコン基板上に絶縁膜を形成する実験を行った。

表１及び図１３は、上記実験条件にてイソプロピルアルコールの流量を０から５００sccmまで変化させた場合における誘電率及び膜硬度／弾性率の関係を示したグラフである。グラフから上記実験条件においては、誘電率が２.５若しくはそれ以下で膜硬度が１.０GPa若しくはそれ以上であってかつ弾性率が５.０GPa若しくはそれ以上となる絶縁膜を形成するための最適なイソプロピルアルコールの流量は５０から４５０sccmであることがわかる。
【表１】

【００５８】
（実験１３）
図１に示したプラズマCVD装置1を用いて、φ３００mmのシリコン基板上に絶縁膜を形成する実験を行った。

表２及び図１４は、上記実験条件にてイソプロピルアルコールの流量を０から５００sccmまで変化させた場合における誘電率及び膜硬度／弾性率の関係を示したグラフである。グラフから上記実験条件においては、誘電率が２.５若しくはそれ以下で膜硬度が１.０GPa若しくはそれ以上であってかつ弾性率が５.０GPa若しくはそれ以上となる絶縁膜を形成するための最適なイソプロピルアルコールの流量は５０から４５０sccmであることがわかる。
【表２】

【００５９】
（実験１４）
図１に示したプラズマCVD装置1を用いて、φ３００mmのシリコン基板上に絶縁膜を形成する実験を行った。

表３及び図１５は、上記実験条件にてジエチルエーテルの流量を０から５００sccmまで変化させた場合における誘電率及び膜硬度／弾性率の関係を示したグラフである。グラフから上記実験条件においては、誘電率が２.５若しくはそれ以下で膜硬度が１.０GPa若しくはそれ以上であってかつ弾性率が５.０GPa若しくはそれ以上となる絶縁膜を形成するための最適なジエチルエーテルの流量は５０から４００sccmであることがわかる。
【表３】

【００６０】
（実験１５）
図１に示したプラズマCVD装置1を用いて、φ３００mmのシリコン基板上に絶縁膜を形成する実験を行った。

表４及び図１６は、上記実験条件にてジエチルエーテルの流量を０から５００sccmまで変化させた場合における誘電率及び膜硬度／弾性率の関係を示したグラフである。グラフから上記実験条件においては、誘電率が２.５若しくはそれ以下で膜硬度が１.０GPa若しくはそれ以上であってかつ弾性率が５.０GPa若しくはそれ以上となる絶縁膜を形成するための最適なジエチルエーテルの流量は１００から４００sccmであることがわかる。
【表４】

【００６１】
上記したように、本発明の実施例に従う低誘電率絶縁膜を形成する方法によれば、ガスの流量及びRF電源の電力密度を最適化することにより、誘電率が低くかつ機械的強度が高い絶縁膜を形成することができた。また、本発明の実施例に従う低誘電率膜を形成する方法によれば、装置コストを増大させることなく、低誘電率絶縁膜を容易に形成することができた。
【００６２】
発明はある実施例によって説明されてきたが、当業者に明らかである他の実施例もまた本発明の態様内にある。したがって、発明の態様は特許請求の範囲によってのみ定義されるべきものである。本発明はさまざまな実施例を含み、上記実施例に限定されるものではない。特に本発明は、これに限定されないが、以下の実施例を含み、上記実施例及び下記実施例のあらゆる組み合わせが容易に達成される。
【００６３】
1)プラズマCVD法により低誘電率絶縁膜を形成する方法であって、複数のアルコキシ基を有するシリコン系炭化水素、CO₂、並びにAr及び／またはHeから成る反応ガスを反応チャンバ内に導入する工程と、該反応チャンバ内部にプラズマ反応場を生成するべく第１のRF電力及び第２のRF電力を重畳することによりRF電力を印加するか若しくは第１のRF電力のみを単独で印加する工程と、それぞれのガスの流量及び各RF電力の出力を最適化する工程と、から成る方法。
【００６４】
2)項目１に記載の方法であって、複数のアルコキシ基を有するシリコン系炭化水素はジメチル-ジメトキシシラン(DM-DMOS)である、ところの方法。
【００６５】
3)項目１に記載の方法であって、複数のアルコキシ基を有するシリコン系炭化水素は1,3-ジメトキシテトラメチルジシロキサン(DMOTMDS)である、ところ
の方法。
【００６６】
4)項目１から３のいずれかに記載の方法であって、反応ガスとしてさらにO₂
若しくはN₂Oが含まれる、ところの方法。
【００６７】
5)プラズマCVD法により低誘電率絶縁膜を形成する方法であって、複数のアルコキシ基を有するシリコン系炭化水素、アルコール並びにAr及び／またはHeから成る反応ガスを反応チャンバ内に導入する工程と、該反応チャンバ内部にプラズマ反応場を生成するべく第１のRF電力及び第２のRF電力を重畳することによりRF電力を印加するか若しくは第１のRF電力のみを単独で印加する工程と、それぞれのガスの流量及び各RF電力の出力を最適化する工程と、か
ら成る方法。
【００６８】
6)項目５に記載の方法であって、複数のアルコキシ基を有するシリコン系炭化水素はジメチル-ジメトキシシラン(DM-DMOS)である、ところの方法。
【００６９】
7)項目５に記載の方法であって、複数のアルコキシ基を有するシリコン系炭化水素は1,3-ジメトキシテトラメチルジシロキサン(DMOTMDS)である、ところの方法。
【００７０】
8)項目５に記載の方法であって、アルコールはエチレングリコールである、ところの方法。
【００７１】
9)項目５に記載の方法であって、アルコールは1,2-プロパンジオールである、ところの方法。
【００７２】
10)項目５に記載の方法であって、アルコールはイソプロピルアルコール(IPA )である、ところの方法。
【００７３】
11)項目５から１０のいずれかに記載の方法であって、反応ガスとしてさらに O₂若しくはN₂Oが含まれる、ところの方法。
【００７４】
12)プラズマCVD法により低誘電率絶縁膜を形成する方法であって、複数のア ルコキシ基を有するシリコン系炭化水素、少なくとも一つの不飽和結合を含 む炭化水素並びにAr及び／またはHeから成る反応ガスを反応チャンバ内に導 入する工程と、該反応チャンバ内部にプラズマ反応場を生成するべく第１の RF電力及び第２のRF電力を重畳することによりRF電力を印加するか若しくは 第１のRF電力のみを単独で印加する工程と、それぞれのガスの流量及び各RF 電力の出力を最適化する工程と、から成る方法。
【００７５】
13)項目１２に記載の方法であって、複数のアルコキシ基を有するシリコン系炭化水素はジメチル-ジメトキシシラン(DM-DMOS)である、ところの方法。
【００７６】
14)項目１２に記載の方法であって、複数のアルコキシ基を有するシリコン系炭化水素は1,3-ジメトキシテトラメチルジシロキサン(DMOTMDS)である、ところの方法。
【００７７】
15)項目１２に記載の方法であって、少なくとも一つの不飽和結合を含む炭化水素はエチレンである、ところの方法。
【００７８】
16)項目１２から１５のいずれかに記載の方法であって、反応ガスとしてさらにO₂若しくはN₂Oが含まれる、ところの方法。
【００７９】
17)プラズマCVD法により低誘電率絶縁膜を形成する方法であって、複数のア ルコキシ基を有するシリコン系炭化水素、N₂並びにAr及び／またはHeから 成る反応ガスを反応チャンバ内に導入する工程と、該反応チャンバ内部にプ ラズマ反応場を生成するべく第１のRF電力及び第２のRF電力を重畳すること によりRF電力を印加するか若しくは第１のRF電力のみを単独で印加する工程 と、それぞれのガスの流量及び各RF電力の出力を最適化する工程と、から成 る方法。
【００８０】
18)項目１７に記載の方法であって、複数のアルコキシ基を有するシリコン系炭化水素はジメチル-ジメトキシシラン(DM-DMOS)である、ところの方法。
【００８１】
19)項目１７に記載の方法であって、複数のアルコキシ基を有するシリコン系炭化水素は1,3-ジメトキシテトラメチルジシロキサン(DMOTMDS)である、ところの方法。
【００８２】
20)項目１７から１９のいずれかに記載の方法であって、反応ガスとしてさらにO₂若しくはN₂Oが含まれる、ところの方法。
【００８３】
21)プラズマCVD法により低誘電率絶縁膜を形成する方法であって、複数のア ルコキシ基を有するシリコン系炭化水素、エーテル並びにAr及び／またはHe から成る反応ガスを反応チャンバ内に導入する工程と、該反応チャンバ内部 にプラズマ反応場を生成するべく第１のRF電力及び第２のRF電力を重畳する ことによりRF電力を印加するか若しくは第１のRF電力のみを単独で印加する 工程と、それぞれのガスの流量及び各RF電力の出力を最適化する工程と、か ら成る方法。
【００８４】
22)項目２１に記載の方法であって、複数のアルコキシ基を有するシリコン系炭化水素はジメチル-ジメトキシシラン(DM-DMOS)である、ところの方法。
【００８５】
23)項目２１に記載の方法であって、複数のアルコキシ基を有するシリコン系炭化水素は1,3-ジメトキシテトラメチルジシロキサン(DMOTMDS)である、ところの方法。
【００８６】
24)項目２１に記載の方法であって、エーテルはジエチルエーテルである、ところの方法。
【００８７】
25)項目２１から２４のいずれかに記載の方法であって、反応ガスとしてさらにO₂若しくはN₂Oが含まれる、ところの方法。
【００８８】
本発明の思想から離れることなく多くの修正が可能であることは当業者の知るところである。したがって、本発明の形式は説明上のものであり、本発明の態様を限定するものではない。
【図面の簡単な説明】
【図１】図１は、本発明に係る絶縁膜の形成に使用するプラズマCVD装置の略示図である。
【図２】図２は、本発明の実施例においてO₂流量を変化させた場合の誘電率及び硬度の関係を示したグラフである。
【図３】図３は、本発明の実施例においてCO₂流量を変化させた場合の誘電率及び硬度の関係を示したグラフである。
【図４】図４は、本発明の実施例において低周波数RF電力の電力密度を変化させた場合の誘電率及び硬度の関係を示したグラフである。
【図５】図５は、本発明の実施例においてエチレングリコールの流量を変化させた場合の誘電率及び硬度の関係を示したグラフである。
【図６】図６は、本発明に係る低周波RF電力(LF電力)が存在しない実施例において、エチレングリコールの流量を変化させた場合の誘電率及び硬度の関係を示したグラフである。
【図７】図７は、本発明の実施例において、1,2-プロパンジオールの流量を変化させた場合の誘電率及び硬度の関係を示したグラフである。
【図８】図８は、本発明に係るLF電力が存在しない実施例において、1,2-プロパンジオールの流量を変化させた場合の誘電率及び硬度の関係を示したグラフである。
【図９】図９は、本発明の実施例において、エチレンの流量を変化させた場合の誘電率及び硬度の関係を示したグラフである。
【図１０】図１０は、本発明に係るLF電力が存在しない実施例において、エチレンの流量を変化させた場合の誘電率及び硬度の関係を示したグラフである。
【図１１】図１１は、本発明の実施例において、N₂の流量を変化させた場合の誘電率及び硬度の関係を示したグラフである。
【図１２】図１２は、本発明に係るLF電力の存在しない実施例において、N₂の流量を変化させた場合の誘電率及び硬度の関係を示したグラフである。
【図１３】図１３は、本発明の実施例において、イソプロピルアルコールの流量を変化させた場合の誘電率及び硬度／弾性係数の関係を示したグラフである。
【図１４】図１４は、本発明に係るLF電力の存在しない実施例において、イソプロピルアルコールの流量を変化させた場合の誘電率及び硬度／弾性係数の関係を示したグラフである。
【図１５】図１５は、本発明の実施例において、ジエチルエーテルの流量を変化させた場合の誘電率及び硬度／弾性係数の関係を示したグラフである。
【図１６】図１６は、本発明に係るLF電力の存在しない実施例において、ジエチルエーテルの流量を変化させた場合の誘電率及び硬度／弾性係数の関係を示したグラフである。
【符号の説明】
1 プラズマCVD装置
2 ヒータ
3 サセプタ
4 半導体ウエハ
5 材料ガス導入口
6 反応チャンバ
7 第１RF電源
8 第２RF電源
9 シャワーヘッド
10 排気口
11 接地[0001]
BACKGROUND OF THE INVENTION
The present invention relates generally to semiconductor technology, and more particularly to a method for forming a silicon-based insulating film having high mechanical strength on a semiconductor substrate by using a plasma CVD (chemical vapor deposition) apparatus.
[0002]
[Prior art]
With the recent demand for higher speed and miniaturization of semiconductors, it is required to reduce the capacitance between wirings in order to prevent signal delay in the multilayer wiring technology field. In order to reduce the capacitance between the wirings, it is necessary to lower the relative dielectric constant of the insulating film between the multilayer wirings, and a low dielectric constant insulating film has been developed.
[0003]
Conventional silicon oxide film SiOx is SiH_FourOr Si (OC₂H_Five)_FourOxygen O as oxidant in silicon material gas such as₂Nitrogen oxide NO or nitrous oxide N₂It is formed by adding heat and plasma or energy, and its relative dielectric constant is about ε = 4.0.
[0004]
In contrast, a low dielectric constant insulating film having a relative dielectric constant ε = 2.3 was formed by spin coating using an inorganic silicon oxide glass (SOG) material.
[0005]
Further, a low dielectric constant fluorinated amorphous carbon film having a relative dielectric constant ε = 2.0 to 2.4 was formed by plasma CVD using CxFyHz as a material gas. Further, a low dielectric constant insulating film having a relative dielectric constant ε = 3.1 was formed by a plasma CVD method using silicon hydrocarbon (for example, P-TMOS (phenyltrimethoxysilane)) as a material gas. Furthermore, a low dielectric constant insulating film of about ε = 2.5 was formed by optimizing conditions by a plasma CVD method using a silicon-based hydrocarbon containing a plurality of alkoxy groups as a material gas.
[0006]
[Problems to be solved by the invention]
However, the conventional approach has the following problems.
[0007]
First, in the case of an inorganic SOG insulating film formed by spin coating, there are problems in that the material is not uniformly distributed on the silicon substrate and that the apparatus used for the curing process after the material coating process is expensive.
[0008]
In addition, in the case of a fluorinated amorphous carbon film formed by a plasma CVD method using CxFyHz as a material gas, the heat resistance of the film is low (370 ° C. or lower), the adhesion with a silicon-based material is poor, and the film Has the disadvantage of low mechanical strength.
[0009]
Further, among the silicon-based hydrocarbons, when P-TMOS is used, the polymerized oligomer cannot form a linear structure like siloxane because it contains three alkoxy groups. As a result, a porous structure is not formed on the silicon substrate, and the relative dielectric constant cannot be reduced to a desired level.
[0010]
Furthermore, when a silicon-based hydrocarbon containing a plurality of alkoxy groups is used as the material gas, the oligomer polymerized by optimizing the conditions forms a linear structure such as siloxane, so that it is porous on the silicon substrate. Although the structure can be formed and the relative dielectric constant can be reduced to a desired level, the oligomer having a linear structure has a problem that the bonding strength between the oligomers is weak and the mechanical strength of the film is low.
[0011]
The present invention has been made in view of the above problems, and an object thereof is to provide a method of forming an insulating film having a low relative dielectric constant and a high mechanical strength.
[0012]
Another object of the present invention is to provide a method for easily forming a low dielectric constant insulating film without increasing the device cost.
[0013]
[Means for Solving the Problems]
In order to solve the above problems, in the embodiment of the present invention, the method for forming a low dielectric constant insulating film according to the present invention comprises the following steps.
[0014]
The method for forming a low dielectric constant insulating film by the plasma CVD method according to the present invention includes a silicon-based hydrocarbon containing a plurality of crosslinkable groups such as an alkoxy group and / or a vinyl group, a crosslinking gas, Introducing a material gas comprising an active gas into the reaction chamber;
Applying the first RF power and the second RF power in a superimposed manner or generating only the first RF power to generate a plasma reaction field in the reaction chamber;
A process of optimizing the flow rate of each material gas and the output of each RF power;
Consists of.
[0015]
As material gas, silicon-based hydrocarbons containing a plurality of crosslinkable groups are used alone or in combination with one or more other silicon-based hydrocarbons having one or more crosslinkable groups . Crosslinkable groups include, but are not limited to, alkoxy groups and / or vinyl groups. For example, if a silicon-based hydrocarbon having no alkoxy group or having only one alkoxy group is used, a linear siloxane oligomer is formed when supplementing oxygen using an oxygen supply gas if necessary. However, in that case, it is difficult to crosslink the oligomer by using a crosslinking gas to increase the mechanical strength of the resulting film. Silicon-based hydrocarbons having no alkoxy groups or having one alkoxy group are used in lesser amounts than silicon-based hydrocarbons having two or more alkoxy groups. In embodiments, 10% or more (including 15%, 20%, 25%, 30%, 40%, 50%, 60%, 70%, 80%, 90% and 100%) In order to form a linear oligomer predominantly or effectively, it is a silicon-based hydrocarbon having two alkoxy groups. Preferably, as a material gas, the silicon-based hydrocarbon containing a plurality of alkoxy groups is a linear compound such as dimethyldimethoxysilane (DM-DMOS) or 1,3-dimethoxytetramethyldisoroxane (DMOTMDS). . Silicon-based hydrocarbons having a cyclic main structure are used in lesser amounts than linear silicon-based hydrocarbons. In the above, the alkoxy group is —OC_nH_{2n + 1}(N is an integer of 1 to 4). The material gas is a compound containing a vinyl group such as 1,3-divinyltetramethyldisiloxane, which is similar to a compound having an alkoxyl group, and the compound can form an oligomer.
[0016]
CO as the crosslinking gas₂, Ethylene glycol, 1,2-propanediol, isopropyl alcohol (IPA), ethylene, N₂Alternatively, any suitable reaction gas such as diethyl ether can be used, which can crosslink silicon-based hydrocarbon oligomers. For example, any suitable alcohol, ether, and / or unsaturated hydrocarbon may be used, such as C_1-6Alkanol and C_4-12An unsaturated hydrocarbon selected from the group consisting of cycloalkanols, and C_1-6Unsaturated hydrocarbon, C_4-12Aromatic hydrocarbon unsaturated compounds and C_4-12An unsaturated hydrocarbon selected from the group consisting of alicyclic hydrocarbon unsaturated compounds. In the above, the compound having more carbon atoms is not limited to this, but 1,4-cyclohexanediol (bp 150 ° C./20 mm), 1,2,4-trivinylcyclohexane (bp 85 to 88 ° C./20 mm). ), 1,4-cyclohexanedimethanol (bp 283 ° C.) and 1,3-cyclopentanediol (80-85 ° C./0.1 Torr). Also, compounds having multiple reactive groups (mixed functionality, ie unsaturated hydrocarbon and alcohol functionality) are also used as crosslinkers, including but not limited to ethylene glycol vinyl ether H₂C = CHOCH₂OH (b.p. 143 ° C), ethylene glycol divinyl ether H₂C = CHOCH₂CH₂OCH = CH₂(b.p. 125-127 ° C.) and 1,4-cyclohexanedimethanol divinyl ether (H₂C = C (OH) -CH₂)₂-(CH₂)₆C like (b.p.126 ℃ / 14mm)_3-20Ether and C such as 1-vinylcyclohexanol (b.p. 74 ° C / 19mm)_5-12Includes cycloalkanol vinyl compounds. The reaction gas that can be used is not limited to the above, but will be described below. Ar, Ne and / or He are used as the inert gas. Also, if sufficient oxygen atoms are not present in the silicon-containing hydrocarbon, O2 as an oxygen supply gas for supplying oxygen into the material gas₂, NO, O_Three, H₂O or N₂O is included.
[0017]
In an embodiment, oligomer cross-linking is effectively realized by superimposing high frequency RF power and low frequency RF power. For example, a combination of high frequency RF power having a frequency of 2 MHz or higher and low frequency RF power having a frequency of 2 MHz or lower is used. Low frequency RF power is 0.5W / cm²Or less (0.2, 0.1, 0.075, 0.05, 0.025 W / cm²As well as a range including any two of them). In contrast, high frequency RF power is 1.5 W / cm.²Or more (2.0, 2.25, 2.5, 2.75, 3.0, 3.25, 3.5 W / cm²And a range including any two of them). Such a high power level can increase the mechanical strength and growth rate of the resulting insulating film.
[0018]
In accordance with an embodiment of the present invention, a silicon-based insulating film having a low dielectric constant and high mechanical strength is formed by using a cross-linking gas and optimizing the flow rate of each gas and the power strength of the RF power source. In an embodiment, the low dielectric constant is achieved by the formation of an oligomer (eg, a siloxane polymer) composed of a residue of a silicon-based hydrocarbon having two or more alkoxy groups, and the high mechanical strength is low. This is accomplished by crosslinking the oligomer while maintaining the rate. Additionally, in accordance with embodiments of the present invention, an insulating film having a low dielectric constant can be easily formed without increasing device cost.
[0019]
The present invention relates to a method for increasing the mechanical strength of an insulating film formed on a semiconductor substrate, which belongs to the above characteristics. In an embodiment, the insulating film is 2.8 or less (2.7, 2.6, 2.5, 2 or 2 depending on, for example, the type of material gas, the type of cross-linking gas, and the strength of RF power. A dielectric constant of 2.4, 2.3, 2.2, 2.1, 2.0, and any two thereof, and 1.0 GPa or more (1.25, 1 .5, 1.75, 2.0, 2.25, 2.5, 2.75, 3.0, etc. (including any two thereof) hardness (mechanical strength) .
[0020]
According to an embodiment of the present invention, a silicon-based insulating film is formed on a substrate, and the film is a plasma polymerization product obtained by the above-described method. In the plasma polymerization product, a silicon-based hydrocarbon compound containing a plurality of alkoxy groups is C_1-6Alkanol, C_1-6Ether, C_1-6Unsaturated hydrocarbons, CO₂And N₂Having a structure that is crosslinked using a crosslinking agent selected from the group consisting of: The plasma polymerization product may have a hardness of 2.5 GPa or higher and a dielectric constant of 2.8 or lower, or 1.0 GPa or higher, depending on, for example, the type of material gas and crosslinking gas and the plasma polymerization conditions. It has a hardness and a modulus of elasticity of 5.0 GPa or more and a dielectric constant of 2.5 or less. In the present invention, the polymerization includes oligomerization, and the oligomer is (M)_nWherein M is a constituent unit, and n is an integer of 2 to 50 including the range of 5 to 30 and 10 to 20.
[0021]
Other aspects, features and advantages of the present invention will become apparent from the following detailed description of the preferred embodiments.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
In an embodiment of the present invention, a method is provided for forming a silicon-based insulating film on a substrate by plasma reaction, the method comprising: (a) (i) a silicon-based hydrocarbon compound containing a plurality of crosslinkable groups Introducing a reaction gas comprising a material gas comprising (ii) a bridging gas and (iii) an inert gas into the reaction chamber in which the substrate is disposed, and (b) forming a plasma reaction field in the reaction chamber. It comprises a step of applying RF power and a step (c) of controlling the flow rate of the reaction gas and the strength of the RF power. In an embodiment, a method for forming a silicon-based insulating film on a substrate by plasma reaction includes (A) (I) a material gas composed of at least one silicon-based hydrocarbon compound containing a plurality of alkoxy groups, (II) C_1-6Alkanol, C_1-6Ether, C_1-6Unsaturated hydrocarbons, CO₂And N₂Introducing a cross-linking gas selected from the group consisting of: (III) a reaction gas comprising an inert gas into the reaction chamber in which the substrate is disposed; and (B) creating a plasma reaction space in the reaction chamber. It comprises a step of applying RF power and a step (C) of controlling the flow rate of the reaction gas and the intensity of the RF power.
[0023]
As described above, the present invention includes various embodiments. For example, RF power is a combination of high frequency power and low frequency power. Also, the high frequency power has a frequency of 2 MHz or more (such as 5, 10, 15, 20, 25, 30, 40, 50, 60 and 70 MHz, and any range including these two). The low frequency power has a frequency of 2 MHz or less (1 MHz, 800, 600, 400, 200, 100 KHz and a range including any two of these). Alternatively, the RF power may be single frequency power. RF power intensity is 1.5W / cm²Or more than that, and when superposing the low frequency RF power, the intensity of the high frequency power is 1.5 W / cm.²Or more, the intensity of the low frequency power is 0.01 W / cm²Or more. Two or more RF power frequencies may be superimposed. For example, high frequency power (for example, 20 to 30 MHz), intermediate frequency power (for example, 1 to 5 MHz), and low frequency power (for example, 200 to 800 KHz) are superimposed.
[0024]
Material gas is chemical formula Si_αO_{α -1}R_{2 α - β +2}(OC_nH_{2n + 1})_βWhere α is an integer from 1 to 3, β is 2 or 3, n is an integer from 1 to 3, and R is C bonded to Si._1-12Hydrocarbon, C_1-12Fluorohydrocarbon, C_1-12Selected from the set consisting of fluorocarbons, H, D, F, Cl, Br and I. In the examples, R is C_1-6It is a hydrocarbon. The source gas also consists of a mixture of one or more compounds described by the above chemical formula. In the embodiment, α is 1 or 2, and β is 2. Such material gases are disclosed in US Pat. Nos. 6,352,945, 6,383,955, and 6,432,846, all of which are hereby incorporated by reference. In the examples, the material gas is dimethyldimethoxysilane (DM-DMOS), 1,3-dimethoxytetramethyldisiloxane (DMOTMDS) or phenylmethyldimethoxysilane (PM-DMOS). Different material gases are mixed or a single material gas is used alone. An additional molecule that is a useful additive to the above material gases is 1,3-divinyltetramethylsilane (DVTMS, [CH₂= CH₂Si (CH_Three)₂]₂O). Such silicon-based compounds with unsaturated hydrocarbons are useful for improving mechanical strength by promoting cross-linking molecules.
[0025]
The flow rate of the reaction gas and the strength of the RF power are formed so as to form an insulating film having a hardness (mechanical strength) of 1.0 GPa or more, or 2.5 GPa or more, depending on the type of material gas, for example. Be controlled.
[0026]
The inert gas is any suitable inert gas including Ar, Ne and He. The reaction gas further comprises an oxygen supply gas. An oxygen supply gas is any suitable gas that can supply oxygen and O₂, NO, O_Three, H₂O and N₂Contains O. In an embodiment, the oxygen supply gas is supplied at a lower flow rate than the material gas. The inert gas is supplied at a flow rate of 15 to 300% (in the embodiment, 50% or more) of the flow rate of the material gas.
[0027]
In an embodiment, the cross-linking gas is a C such as ethylene glycol, 1,2-propanediol and isopropyl alcohol._2-4Alkanol. In other embodiments, the cross-linking gas is a C such as diethyl ether._2-4Ether. In yet another embodiment, the crosslinking gas is C₂H_Four, C_ThreeH_Four, C_ThreeH₆, C_FourH₈, C_ThreeH_Five(CH_Three) And C_ThreeH_Four(CH_Three)₂Like C_2-4It is an unsaturated hydrocarbon. C_4-12Aromatic hydrocarbons and C_4-12A compound having a higher carbon atom skeleton, such as an alicyclic hydrocarbon, is also used as a crosslinking agent if it possesses a reactive group. Such compounds include, but are not limited to, 1,4-cyclohexanediol (bp 150 ° C./20 mm), 1,4-cyclohexanedimethanol (bp 283 ° C.) and 1,3-cyclopentanediol (80-85 C such as ° C / 0.1 Torr)_4-12C, such as cycloalkanol and 1,2,4-trivinylcyclohexane (b.p. 85-88 ° C./20 mm)_4-12Alicyclic hydrocarbon unsaturated compounds are included.
[0028]
In addition, compounds with multiple reactive groups (mixed functionality, ie unsaturated hydrocarbon and alcohol functionality) are also used as crosslinkers, including but not limited to ethylene glycol vinyl ether H₂C = CHOCH₂OH (b.p. 143 ° C), ethylene glycol divinyl ether H₂C = CHOCH₂CH₂OCH = CH₂(b.p. 125-127 ° C.) and 1,4-cyclohexanedimethanol divinyl ether (H₂C = C (OH) -CH₂)₂-(CH₂)₆C like (b.p.126 ℃ / 14mm)_3-20Ethers and C such as 1-vinylcyclohexol (b.p. 74 ° C./19 mm)_5-12Includes cycloalkanol vinyl compounds. The high molecular weight type material gas can incorporate a desired bridging ligand in combination with a cyclic compound. They can cross-link linear siloxane chains, but can also reduce film density to a greater degree than other types of material gases, so that the desired hardness (eg, mechanical properties) can be achieved without sacrificing dielectric constant. Strength) can be achieved.
[0029]
The cross-linking gas is used alone or in any combination of the above. The cross-linking gas is supplied at a flow rate effective to cross-link the oligomer of the compound of the material gas, thereby increasing the mechanical strength of the insulating film formed on the substrate. The flow rate of the cross-linking gas is, for example, 20 to 500% of the flow rate of the material gas, depending on the type of material gas.
[0030]
In an embodiment, the reaction gas is excited upstream of the reaction chamber. In this embodiment, the reaction gas is excited in a remote plasma chamber disposed upstream of the reactor. Material gas and additive gas (crosslinking gas and / or inert gas) are introduced into the remote plasma chamber. In this case, the reaction space is composed of the inside of the remote plasma chamber, the inside of the reactor, and the inside of the piping connecting the remote plasma chamber and the reactor. Due to the use of the interior of the remote plasma chamber, the internal space of the reactor is considerably reduced, thus reducing the distance between the upper and lower electrodes. This not only reduces the size of the reactor, but also allows the plasma to be controlled uniformly over the entire substrate surface. Any suitable remote plasma chamber and any suitable operating conditions may be used in the present invention. For example, usable equipment and conditions include US patent application Ser. No. 09 / 511,934, filed Feb. 24, 2000, and US Patent Application No. 09 / 764,523, filed Jan. 18, 2001, as well as US Nos. 5,788,778 and 5,788,799. The above disclosure is hereby incorporated by reference.
[0031]
The excitation of the reaction gas includes exciting the additive gas and bringing the excited additive gas into contact with the material gas. The reaction gas is excited in the reactor or upstream of the reactor. As described above, both the material gas and the additive gas are excited in the remote plasma chamber. Alternatively, the reaction gas may be excited by exciting the additive gas in the remote plasma chamber and mixing it with the material gas downstream of the remote plasma chamber. Alternatively, the reaction gas may be heated and excited in a preheated chamber installed upstream of the reactor, and the film is deposited on a substrate in the reactor. Material gas and additive gas are introduced into the preheating chamber. In this case, the reaction space includes a preheating chamber, a reactor, and a pipe connecting the preheating chamber and the reactor. By using the interior of the preheating chamber, the interior of the reactor is greatly reduced and the distance between the upper and lower electrodes is reduced. This not only reduces the size of the reactor, but can also control the plasma uniformly over the entire substrate surface. Any suitable remote plasma chamber and any suitable operating conditions may be used in the present invention. For example, usable equipment and conditions are disclosed in the above references.
[0032]
Furthermore, the excitation of the reaction gas comprises exciting the additive gas and bringing the excited additive gas into contact with the material gas. In this embodiment, the additive gas is excited in the remote plasma chamber, the material gas is heated in the preheating chamber where the excited additive gas and the material gas are in contact, and then the reaction gas is reacted to deposit the film. Flows in. In this case, since only additive gas is present in the remote plasma chamber, unwanted particle deposition on the surface of the remote plasma chamber causing ignition or ignition failure is effectively prevented. The material gas is mixed with the additive gas excited downstream of the remote plasma chamber.
[0033]
In other embodiments, other plasma conditions are employed such as using a pulsed plasma for high and / or low frequency radiation for further stabilization of film deposition. For example, a cycle of 10 to 100 msec and a duty of 10 to 90% (radiation time / (radiation time + non-radiation time)) are suitable.
[0034]
In another aspect of the invention, a method is provided for increasing the mechanical strength of a silicon-based insulating film formed on a substrate, the method comprising: (a) C_1-6Alkanol, C_1-6Ether, C_1-6Unsaturated hydrocarbons, CO₂And N₂A step of mixing a cross-linking gas selected from the group consisting of an inert gas in a material gas comprising a silicon-based hydrocarbon compound having a plurality of alkoxy groups, and (b) a reaction in a reaction chamber in which a substrate is disposed. Introducing a mixed gas as a gas; (c) applying RF power so as to create a plasma reaction space inside the reaction chamber; and (d) controlling the flow rate of the reactive gas and the intensity of the RF power. , Consisting of.
[0035]
To form oligomers in the present invention, the residence time of the reaction gas is controlled as disclosed in US Pat. Nos. 6,352,945, 6,383,955, and 6,432,846, which are hereby incorporated by reference.
[0036]
The flow rate of the reaction gas is determined based on the strength of the RF power, the pressure selected for the reaction, and the type of material gas and cross-linking gas. The reaction pressure is usually in the range of 1 to 10 Torr, but is preferably in the range of 3 to 7 Torr to maintain a stable plasma. This reaction pressure is relatively high in order to increase the residence time of the reaction gas. The total flow rate of the reaction gas is important for reducing the relative dielectric constant of the generated film. In general, the longer the residence time, the lower the dielectric constant. The material gas flow required to form the film depends on the desired growth rate and the area of the substrate on which the film is formed. For example, in order to form a film on a substrate (radius r = 100 mm) at a growth rate of 300 nm / min, a material gas of at least 50 sccm (preferably 100 to 500 sccm including 150, 200, 250 sccm) is present in the reaction gas. Is expected to be included.
[0037]
In order to regulate the reaction in the gas phase, it is advantageous to add a small amount of inert gas to the reaction chamber. Helium (He) and argon (Ar) are inert gases and have different first ionization energies, 24.56 eV and 15.76 eV, respectively. Therefore, the reaction of the material gas in the gas phase is controlled by adding both He or Ar alone or in combination in a predetermined amount. Additionally or alternatively, neon (Ne) may be used for the same purpose. The molecules of the reaction gas undergo a polymerization reaction in the gas phase to form oligomers. The oligomer is desired to have a 1: 1 O: Si ratio. However, when the oligomer forms a film on the substrate, the oligomer further undergoes a polymerization reaction to achieve a higher oxygen ratio. The ratio varies depending on the dielectric constant and other characteristics of the film formed on the substrate. In consideration of the above and the reaction efficiency, oxygen is supplied to adjust the Si / O ratio in the reaction gas.
[0038]
The invention will be further described in detail with reference to the drawings. FIG. 1 schematically shows a plasma CVD apparatus used in a method for forming an insulating film having a low dielectric constant according to an embodiment of the present invention. The plasma CVD apparatus 1 includes a reaction chamber 6. A susceptor 3 for mounting the semiconductor wafer 4 is provided inside the reaction chamber 6. The susceptor 3 is supported by the heater 2. The heater 2 maintains the semiconductor wafer 4 at a predetermined temperature (for example, 350 to 450 ° C.). The susceptor 3 also serves as one electrode for generating plasma, and is grounded 11 through the reaction chamber 6. A shower head 9 is provided on the inner ceiling of the reaction chamber 6 so as to face the susceptor 3 in parallel. The shower head 9 has many pores on the bottom surface. From there, a reaction gas (including a material gas, a crosslinking gas, an inert gas, and other additive gases) described below is uniformly ejected toward the semiconductor wafer 4. Material gas, bridging gas and inert gas are separately fed into the reaction chamber using different gas lines (not shown). A reaction gas inlet 5 is provided at the center of the shower head 9, and the reaction gas is introduced into the shower head 9 through a gas line (not shown). The gas inlet 5 is electrically insulated from the reaction chamber 6. The shower head 9 also serves as the other electrode for generating plasma, and is connected to a first RF power source 7 and a second RF power source 8 installed outside. As a result, a plasma reaction field is generated in the vicinity of the semiconductor wafer 4. An exhaust port 10 is provided at the bottom of the reaction chamber 6 and is connected to an external vacuum pump (not shown).
[0039]
Next, a method for forming a low dielectric constant insulating film according to an embodiment of the present invention will be described. The method includes the step of introducing a reaction gas comprising a main material gas, a sub-material gas (crosslinking gas and additionally an oxygen supply gas) and an additive gas (inert gas) into the shower head 9 through the reaction gas inlet 5. . The main material gas is a silicon-based hydrocarbon containing a plurality of alkoxy groups, preferably DM-DMOS (dimethyldimethoxysilane). Secondary material gas is CO₂Alcohols such as ethylene glycol, 1,2 propanediol and isopropyl alcohol (IPA), hydrocarbons containing at least one unsaturated bond such as ethylene, N₂Or an ether such as diethyl ether. If it is necessary to control the Si / O ratio, it is necessary to add more O₂, O_Three, NO, H₂O or N₂O can also be added. The additive gas is an inert gas such as Ar, Ne and / or He.
[0040]
It is useful to independently use alternative combinations of inclined or different gas flows and / or gases to produce materials that are inclined and / or have different compositions at the initial interface and final surface of the membrane. is there.
[0041]
In addition, the low dielectric constant insulating film forming method according to the embodiment of the present invention includes a step of applying RF power by superimposing the first RF power and the second RF power on the shower head 9 or the first RF power. Including the step of applying the singly. The frequency of the first RF power source 7 is preferably 2 MHz or higher, and the frequency of the second RF power source 8 is preferably 2 MHz or lower. By applying RF power to the showerhead 9, a plasma reaction field is formed in the vicinity of the semiconductor wafer 4. The reactive gas introduced through the reactive gas inlet 5 is excited in the plasma, and a desired insulating film is formed on the semiconductor wafer.
[0042]
According to the method according to the embodiment of the present invention, CO as a secondary source gas.₂Alcohols such as ethylene glycol, 1,2 propanediol and isopropyl alcohol (IPA), hydrocarbons containing at least one unsaturated bond such as ethylene, N₂Alternatively, by introducing an ether such as diethyl ether, the linear oligomer is crosslinked, and the mechanical strength of the film can be improved while maintaining a low dielectric constant. Moreover, the mechanical strength of the film can be further improved by superimposing the second RF power on the first RF power.
[0043]
Furthermore, the method for forming a low dielectric constant insulating film according to the embodiment of the present invention includes a step of optimizing the flow rate of each material gas and the outputs of the first and second RF power sources. The output optimization was performed by the following experiment. Here, the frequency of the first RF power source 7 is fixed at 27.12 MHz, and the frequency of the second RF power source 8 is fixed at 400 kHz. However, other frequencies may be used.
[0044]
In the experiment, by optimizing the flow rate of each gas and the output of the first and second RF power sources, when DM-DMOS (dimethyl-dimethoxysilane) is used as the main material gas, the relative dielectric constant is 2.8 or Below that, an insulating film with a film hardness of 2.5 GPa or higher is formed, and when DMOTMDS (1,3-dimethoxytetramethyldisiloxane) is used as the main material gas, the dielectric constant is 2.5 or higher. An insulating film having a film hardness of 1.0 GPa or higher is formed below.
[0045]
【Example】
Hereinafter, an experiment for optimizing the flow rate of each gas and the output of each RF power source in the method for forming a low dielectric constant insulating film according to the present invention will be described.
[0046]
(Experiment 1)
Using the plasma CVD apparatus 1 shown in FIG. 1, an experiment for forming an insulating film on a φ300 mm silicon substrate was conducted.

Figure 2 shows the O under the above experimental conditions.₂5 is a graph showing the relationship between the dielectric constant and the film hardness when the flow rate is changed from 0 to 200 sccm. From the graph, under the above experimental conditions, the optimum O for forming an insulating film having a dielectric constant of 2.8 or less and a film hardness of 2.5 GPa or more.₂It can be seen that the flow rate is 50 to 150 sccm.
[0047]
(Experiment 2)
Using the plasma CVD apparatus 1 shown in FIG. 1, an experiment for forming an insulating film on a φ300 mm silicon substrate was conducted.

Fig. 3 shows CO under the above experimental conditions.₂5 is a graph showing the relationship between the dielectric constant and the film hardness when the flow rate is changed from 0 to 1000 sccm. From the graph, under the above experimental conditions, the optimum CO for forming an insulating film having a dielectric constant of 2.8 or lower and a film hardness of 2.5 GPa or higher is shown.₂It can be seen that the flow rate is between 100 and 900 sccm.
[0048]
(Experiment 3)
Using the plasma CVD apparatus 1 shown in FIG. 1, an experiment for forming an insulating film on a φ300 mm silicon substrate was conducted.

FIG. 4 shows that the power density of the second RF power supply is 0 to 0.5 W / cm under the above experimental conditions.²It is the graph which showed the relationship between the dielectric constant when it was made to change to film thickness, and film | membrane hardness. From the graph, under the above experimental conditions, the optimum power density of the second RF power source for forming an insulating film having a dielectric constant of 2.8 or lower and a film hardness of 2.5 GPa or higher is 0.025 to 0. .4 W / cm²It can be seen that it is.
[0049]
(Experiment 4)
Using the plasma CVD apparatus 1 shown in FIG. 1, an experiment for forming an insulating film on a φ300 mm silicon substrate was conducted.

FIG. 5 is a graph showing the relationship between the dielectric constant and the film hardness when the flow rate of ethylene glycol is changed from 0 to 200 sccm under the above experimental conditions. From the graph, it is understood that the optimum ethylene glycol flow rate for forming an insulating film having a dielectric constant of 2.8 or lower and a film hardness of 2.5 GPa or higher is 50 to 100 sccm under the above experimental conditions. .
[0050]
(Experiment 5)
Using the plasma CVD apparatus 1 shown in FIG. 1, an experiment for forming an insulating film on a φ300 mm silicon substrate was conducted.

FIG. 6 is a graph showing the relationship between the dielectric constant and the film hardness when the flow rate of ethylene glycol is changed from 0 to 200 sccm under the above experimental conditions. From the graph, it is understood that the optimum ethylene glycol flow rate for forming an insulating film having a dielectric constant of 2.8 or lower and a film hardness of 2.5 GPa or higher is 100 to 150 sccm under the above experimental conditions. .
[0051]
(Experiment 6)
Using the plasma CVD apparatus 1 shown in FIG. 1, an experiment for forming an insulating film on a φ300 mm silicon substrate was conducted.

FIG. 7 is a graph showing the relationship between dielectric constant and film hardness when the flow rate of 1,2 propanediol is varied from 0 to 400 sccm under the above experimental conditions. From the graph, under the above experimental conditions, the optimum 1,2 propanediol flow rate for forming an insulating film having a dielectric constant of 2.8 or less and a film hardness of 2.5 GPa or more is 50 to 300 sccm. I understand that.
[0052]
(Experiment 7)
Using the plasma CVD apparatus 1 shown in FIG. 1, an experiment for forming an insulating film on a φ300 mm silicon substrate was conducted.

FIG. 8 is a graph showing the relationship between dielectric constant and film hardness when the flow rate of 1,2 propanediol is varied from 0 to 400 sccm under the above experimental conditions. From the graph, under the above experimental conditions, the optimum 1,2 propanediol flow rate for forming an insulating film having a dielectric constant of 2.8 or lower and a film hardness of 2.5 GPa or higher is 200 to 300 sccm. I understand that.
[0053]
(Experiment 8)
Using the plasma CVD apparatus 1 shown in FIG. 1, an experiment for forming an insulating film on a φ300 mm silicon substrate was conducted.

FIG. 9 is a graph showing the relationship between the dielectric constant and the film hardness when the flow rate of ethylene is changed from 0 to 500 sccm under the above experimental conditions. From the graph, it can be seen that under the above experimental conditions, the optimum ethylene flow rate for forming an insulating film having a dielectric constant of 2.8 or less and a film hardness of 2.5 GPa or more is 50 to 450 sccm.
[0054]
(Experiment 9)
Using the plasma CVD apparatus 1 shown in FIG. 1, an experiment for forming an insulating film on a φ300 mm silicon substrate was conducted.

FIG. 10 is a graph showing the relationship between the dielectric constant and the film hardness when the flow rate of ethylene is changed from 0 to 500 sccm under the above experimental conditions. It can be seen from the graph that the optimum ethylene flow rate for forming an insulating film having a dielectric constant of 2.8 or less and a film hardness of 2.5 GPa or more is 300 to 450 sccm under the above experimental conditions.
[0055]
(Experiment 10)
Using the plasma CVD apparatus 1 shown in FIG. 1, an experiment for forming an insulating film on a φ300 mm silicon substrate was conducted.

FIG. 11 shows N under the above experimental conditions.₂5 is a graph showing the relationship between the dielectric constant and the film hardness when the flow rate is changed from 0 to 500 sccm. From the graph, under the above experimental conditions, the optimum N for forming an insulating film having a dielectric constant of 2.8 or less and a film hardness of 2.5 GPa or more.₂It can be seen that the flow rate is between 100 and 400 sccm.
[0056]
(Experiment 11)
Using the plasma CVD apparatus 1 shown in FIG. 1, an experiment for forming an insulating film on a φ300 mm silicon substrate was conducted.

FIG. 12 shows N under the above experimental conditions.₂5 is a graph showing the relationship between the dielectric constant and the film hardness when the flow rate is changed from 0 to 500 sccm. From the graph, under the above experimental conditions, the optimum N for forming an insulating film having a dielectric constant of 2.8 or less and a film hardness of 2.5 GPa or more.₂It can be seen that the flow rate is 200 to 400 sccm.
[0057]
(Experiment 12)
Using the plasma CVD apparatus 1 shown in FIG. 1, an experiment for forming an insulating film on a φ300 mm silicon substrate was conducted.

Table 1 and FIG. 13 are graphs showing the relationship between dielectric constant and film hardness / elastic modulus when the flow rate of isopropyl alcohol is changed from 0 to 500 sccm under the above experimental conditions. From the graph, the optimum conditions for forming an insulating film having a dielectric constant of 2.5 or less, a film hardness of 1.0 GPa or more, and an elastic modulus of 5.0 GPa or more under the above experimental conditions. It can be seen that the flow rate of isopropyl alcohol is 50 to 450 sccm.
[Table 1]

[0058]
(Experiment 13)
Using the plasma CVD apparatus 1 shown in FIG. 1, an experiment for forming an insulating film on a φ300 mm silicon substrate was conducted.

Table 2 and FIG. 14 are graphs showing the relationship between dielectric constant and film hardness / elastic modulus when the flow rate of isopropyl alcohol is changed from 0 to 500 sccm under the above experimental conditions. From the graph, the optimum conditions for forming an insulating film having a dielectric constant of 2.5 or less, a film hardness of 1.0 GPa or more, and an elastic modulus of 5.0 GPa or more under the above experimental conditions. It can be seen that the flow rate of isopropyl alcohol is 50 to 450 sccm.
[Table 2]

[0059]
(Experiment 14)
Using the plasma CVD apparatus 1 shown in FIG. 1, an experiment for forming an insulating film on a φ300 mm silicon substrate was conducted.

Table 3 and FIG. 15 are graphs showing the relationship between dielectric constant and film hardness / elastic modulus when the flow rate of diethyl ether is changed from 0 to 500 sccm under the above experimental conditions. From the graph, the optimum conditions for forming an insulating film having a dielectric constant of 2.5 or less, a film hardness of 1.0 GPa or more, and an elastic modulus of 5.0 GPa or more under the above experimental conditions. It can be seen that the flow rate of neat diethyl ether is 50 to 400 sccm.
[Table 3]

[0060]
(Experiment 15)
Using the plasma CVD apparatus 1 shown in FIG. 1, an experiment for forming an insulating film on a φ300 mm silicon substrate was conducted.

Table 4 and FIG. 16 are graphs showing the relationship between dielectric constant and film hardness / elastic modulus when the flow rate of diethyl ether was changed from 0 to 500 sccm under the above experimental conditions. From the graph, under the above experimental conditions, it is optimum to form an insulating film having a dielectric constant of 2.5 or less, a film hardness of 1.0 GPa or more, and an elastic modulus of 5.0 GPa or more. It can be seen that the flow rate of pure diethyl ether is 100 to 400 sccm.
[Table 4]

[0061]
As described above, according to the method of forming the low dielectric constant insulating film according to the embodiment of the present invention, the dielectric constant is low and the mechanical strength is high by optimizing the gas flow rate and the power density of the RF power source. An insulating film could be formed. Further, according to the method for forming a low dielectric constant film according to the embodiment of the present invention, the low dielectric constant insulating film can be easily formed without increasing the device cost.
[0062]
Although the invention has been described in terms of certain embodiments, other embodiments that will be apparent to those skilled in the art are also within the scope of the invention. Accordingly, aspects of the invention should be defined only by the claims. The present invention includes various embodiments and is not limited to the above embodiments. In particular, the present invention includes, but is not limited to, the following examples, and any combination of the above examples and the following examples can be easily achieved.
[0063]
1) A method for forming a low dielectric constant insulating film by plasma CVD, which is a silicon-based hydrocarbon having a plurality of alkoxy groups, CO₂And introducing a reaction gas comprising Ar and / or He into the reaction chamber and superimposing the first RF power and the second RF power to generate a plasma reaction field inside the reaction chamber. A method comprising: applying power or applying only the first RF power alone; and optimizing the flow rate of each gas and the output of each RF power.
[0064]
2) The method according to item 1, wherein the silicon-based hydrocarbon having a plurality of alkoxy groups is dimethyl-dimethoxysilane (DM-DMOS).
[0065]
3) The method according to item 1, wherein the silicon-based hydrocarbon having a plurality of alkoxy groups is 1,3-dimethoxytetramethyldisiloxane (DMOTMDS),
the method of.
[0066]
4) The method according to any one of items 1 to 3, further comprising O as a reaction gas.₂
Or N₂Where O is included.
[0067]
5) A method of forming a low dielectric constant insulating film by a plasma CVD method, the step of introducing a reaction gas comprising a silicon-based hydrocarbon having a plurality of alkoxy groups, an alcohol, and Ar and / or He into a reaction chamber; Applying RF power by superimposing the first RF power and the second RF power to generate a plasma reaction field within the reaction chamber, or applying only the first RF power alone; A process for optimizing each gas flow rate and each RF power output;
A method consisting of
[0068]
6) The method according to item 5, wherein the silicon-based hydrocarbon having a plurality of alkoxy groups is dimethyl-dimethoxysilane (DM-DMOS).
[0069]
7) The method according to item 5, wherein the silicon-based hydrocarbon having a plurality of alkoxy groups is 1,3-dimethoxytetramethyldisiloxane (DMOTMDS).
[0070]
8) The method according to item 5, wherein the alcohol is ethylene glycol.
[0071]
9) The method according to item 5, wherein the alcohol is 1,2-propanediol.
[0072]
10) The method according to item 5, wherein the alcohol is isopropyl alcohol (IPA).
[0073]
11) The method according to any one of items 5 to 10, wherein the reaction gas is further O₂Or N₂Where O is included.
[0074]
12) A method for forming a low dielectric constant insulating film by a plasma CVD method, comprising a silicon-based hydrocarbon having a plurality of alkoxy groups, a hydrocarbon containing at least one unsaturated bond, and Ar and / or He. Introducing the reaction gas into the reaction chamber and applying RF power by superimposing the first RF power and the second RF power to generate a plasma reaction field in the reaction chamber, The method comprises the steps of applying only the RF power of each and the step of optimizing the flow rate of each gas and the output of each RF power.
[0075]
13) The method according to item 12, wherein the silicon-based hydrocarbon having a plurality of alkoxy groups is dimethyl-dimethoxysilane (DM-DMOS).
[0076]
14) The method according to item 12, wherein the silicon-based hydrocarbon having a plurality of alkoxy groups is 1,3-dimethoxytetramethyldisiloxane (DMOTMDS).
[0077]
15) The method according to item 12, wherein the hydrocarbon containing at least one unsaturated bond is ethylene.
[0078]
16) The method according to any one of Items 12 to 15, further comprising O as a reaction gas.₂Or N₂Where O is included.
[0079]
17) A method of forming a low dielectric constant insulating film by plasma CVD, which is a silicon-based hydrocarbon having a plurality of alkoxy groups, N₂And introducing a reaction gas composed of Ar and / or He into the reaction chamber, and superimposing the first RF power and the second RF power to generate a plasma reaction field inside the reaction chamber. A method comprising: applying power or applying only the first RF power alone; and optimizing the flow rate of each gas and the output of each RF power.
[0080]
18) The method according to item 17, wherein the silicon-based hydrocarbon having a plurality of alkoxy groups is dimethyl-dimethoxysilane (DM-DMOS).
[0081]
19) The method according to item 17, wherein the silicon-based hydrocarbon having a plurality of alkoxy groups is 1,3-dimethoxytetramethyldisiloxane (DMOTMDS).
[0082]
20) The method according to any one of items 17 to 19, further comprising O as a reaction gas.₂Or N₂Where O is included.
[0083]
21) A method of forming a low dielectric constant insulating film by a plasma CVD method, which is a step of introducing a reaction gas comprising a plurality of alkoxy group-containing silicon hydrocarbons, ethers, and Ar and / or He into the reaction chamber. Applying RF power by superimposing the first RF power and the second RF power to generate a plasma reaction field inside the reaction chamber, or applying only the first RF power alone. And optimizing each gas flow rate and each RF power output.
[0084]
22) The method according to item 21, wherein the silicon-based hydrocarbon having a plurality of alkoxy groups is dimethyl-dimethoxysilane (DM-DMOS).
[0085]
23) The method according to item 21, wherein the silicon-based hydrocarbon having a plurality of alkoxy groups is 1,3-dimethoxytetramethyldisiloxane (DMOTMDS).
[0086]
24) The method according to item 21, wherein the ether is diethyl ether.
[0087]
25) The method according to any one of items 21 to 24, further comprising O as a reaction gas.₂Or N₂Where O is included.
[0088]
Those skilled in the art will appreciate that many modifications are possible without departing from the spirit of the invention. Accordingly, the form of the invention is illustrative and does not limit aspects of the invention.
[Brief description of the drawings]
FIG. 1 is a schematic view of a plasma CVD apparatus used for forming an insulating film according to the present invention.
FIG. 2 is a schematic diagram of an O according to an embodiment of the present invention.₂It is the graph which showed the relationship between the dielectric constant and hardness at the time of changing a flow rate.
FIG. 3 shows CO in an embodiment of the present invention.₂It is the graph which showed the relationship between the dielectric constant and hardness at the time of changing a flow rate.
FIG. 4 is a graph showing the relationship between dielectric constant and hardness when the power density of low-frequency RF power is changed in an embodiment of the present invention.
FIG. 5 is a graph showing the relationship between dielectric constant and hardness when the flow rate of ethylene glycol is changed in an example of the present invention.
FIG. 6 is a graph showing the relationship between dielectric constant and hardness when the flow rate of ethylene glycol is changed in an example in which low-frequency RF power (LF power) according to the present invention does not exist.
FIG. 7 is a graph showing the relationship between dielectric constant and hardness when the flow rate of 1,2-propanediol is changed in an example of the present invention.
FIG. 8 is a graph showing the relationship between dielectric constant and hardness when the flow rate of 1,2-propanediol is changed in an example in which LF power does not exist according to the present invention.
FIG. 9 is a graph showing the relationship between dielectric constant and hardness when the flow rate of ethylene is changed in an example of the present invention.
FIG. 10 is a graph showing the relationship between dielectric constant and hardness when the flow rate of ethylene is changed in an example in which LF power does not exist according to the present invention.
FIG. 11 is a diagram showing N in an embodiment of the present invention.₂It is the graph which showed the relationship between the dielectric constant when changing the flow volume of and the hardness.
FIG. 12 shows an embodiment in which LF power does not exist according to the present invention.₂It is the graph which showed the relationship between the dielectric constant when changing the flow volume of and the hardness.
FIG. 13 is a graph showing the relationship between the dielectric constant and the hardness / elastic coefficient when the flow rate of isopropyl alcohol is changed in the example of the present invention.
FIG. 14 is a graph showing the relationship between dielectric constant and hardness / elastic coefficient when the flow rate of isopropyl alcohol is changed in an example in which LF power does not exist according to the present invention.
FIG. 15 is a graph showing the relationship between the dielectric constant and the hardness / elastic coefficient when the flow rate of diethyl ether is changed in the example of the present invention.
FIG. 16 is a graph showing the relationship between the dielectric constant and the hardness / elastic modulus when the flow rate of diethyl ether is changed in an example where LF power does not exist according to the present invention.
[Explanation of symbols]
1 Plasma CVD equipment
2 Heater
3 Susceptor
4 Semiconductor wafer
5 Material gas inlet
6 Reaction chamber
7 1st RF power supply
8 Second RF power supply
9 Shower head
10 Exhaust port
11 Ground

Claims (29)

A method for forming a silicon-based insulating film on a substrate by plasma reaction,
(i) a material gas consisting of dimethyldimethoxysilane or 1,3- dimethoxytetramethyldisiloxane , and (ii) a bridging gas selected from the group consisting of alcohols, ethers, unsaturated hydrocarbons, CO2 and N2. Wherein the alcohol is selected from the group consisting of C _1-6 alkanols and C _4-12 cycloalkanols, and the ether is selected from the group consisting of C _3-20 ethers and C _5-12 cycloalkanol vinyl compounds, The unsaturated hydrocarbon is selected from the group consisting of C _2-4 unsaturated hydrocarbons and C _4-12 alicyclic hydrocarbon unsaturated compounds, and (iii) an inert gas; Introducing a reaction gas comprising: into a reaction chamber in which a substrate is disposed;
Applying RF power to form a plasma reaction field within the reaction chamber;
Controlling the flow rate of the reaction gas and the intensity of the RF power;
A method consisting of: 2. The method of claim 1, wherein the RF power is a combination of high frequency power and low frequency power. 3. The method of claim 2, wherein the high frequency power has a frequency of 2 MHz or higher and the low frequency power has a frequency of 2 MHz or lower. 2. The method of claim 1, wherein the RF power is single frequency power. 2. The method according to claim 1, wherein the flow rate of the reaction gas and the strength of the electric power are controlled so as to form an insulating film having a hardness of 1.0 GPa or more. 2. The method according to claim 1, wherein the flow rate of the reaction gas and the strength of the electric power are controlled so as to form an insulating film having a hardness of 2.5 GPa or more. 2. The method according to claim 1, wherein the inert gas is selected from the set consisting of Ar, Ne and He. The method of claim 1, wherein the reaction gas further comprises an oxygen supply gas. The method of claim 8, the oxygen feed gas is selected from the group consisting of O ₂ and N ₂ O, where methods. 9. The method according to claim 8, wherein the oxygen supply gas is supplied at a flow rate less than the flow rate of the material gas. 2. The method of claim 1, wherein the RF power intensity is 1.5 W / cm < ² > or higher. 3. The method according to claim 2, wherein the intensity of the high frequency power is 1.5 W / cm ² or higher and the intensity of the low frequency power is 0.01 W / cm ² or higher. . 2. The method according to claim 1, wherein the inert gas is supplied at a flow rate of 15 to 300% of the flow rate of the material gas. 2. The method according to claim 1, wherein the crosslinking gas is a _C2-4 alkanol. 15. The method according to claim 14, wherein the _C2-4 alkanol is ethylene glycol, 1,2-propanediol or isopropyl alcohol. 2. The method according to claim 1, wherein the crosslinking gas is _C2-4 ether. 17. A method according to claim 16, wherein the _C2-4 ether is diethyl ether. 2. The method of claim 1, wherein the _C2-4 unsaturated hydrocarbon is ethylene. 2. The method according to claim 1, wherein the cross-linking gas is supplied at a flow rate effective to cross-link the oligomer of the compound of the material gas, thereby increasing the hardness of the insulating film formed on the substrate. Method. 20. The method according to claim 19, wherein the flow rate of the crosslinking gas is 20 to 500% of the flow rate of the material gas. The method of claim 1, wherein the reaction gas is excited upstream of the reaction chamber. A method for increasing the mechanical strength of a silicon-based insulating film formed on a substrate,
A material gas composed of dimethyldimethoxysilane or 1,3- dimethoxytetramethyldisiloxane and a crosslinking gas selected from the group consisting of alcohol, ether, unsaturated hydrocarbon, CO2 and N2 , wherein the alcohol is C _{1 -6} alkanol and C _4-12 cycloalkanol selected from the group consisting of C _3-20 ether and C _5-12 cycloalkanol vinyl compound, and the unsaturated hydrocarbon is C ₂ A step of mixing a crosslinking gas selected from the group consisting of _-4 unsaturated hydrocarbons and C _4-12 alicyclic hydrocarbon unsaturated compounds with an inert gas;
Introducing a mixed gas as a reaction gas into a reaction chamber in which a substrate is disposed;
Applying RF power to form a plasma reaction field within the reaction chamber;
Controlling the flow rate of the reaction gas and the intensity of the RF power;
A method consisting of: 23. The method of claim 22, wherein the RF power is a combination of high frequency power and low frequency power. 23. The method of claim 22, wherein the high frequency power has a frequency of 2 MHz or higher and the low frequency power has a frequency of 2 MHz or lower. 23. The method of claim 22, wherein the cross-linking gas is supplied at a flow rate effective to cross-link the oligomer of the compound of the material gas, thereby providing a hardness of 1.0 GPa or higher, 5.0 GPa or higher. A method where an elastic modulus and a dielectric constant of 2.5 or less can be obtained. 23. The method of claim 22, wherein the cross-linking gas is provided at a flow rate effective to cross-link the oligomer of the compound of the material gas, thereby providing a hardness of 2.5 GPa or higher and 2.8 or lower. Where the dielectric constant can be obtained. 23. The method of claim 22, wherein the reaction gas is excited upstream of the reaction chamber. A silicon-based insulating film formed on the substrate, the silicon-based insulating film,
(a) (i) A material gas composed of dimethyldimethoxysilane or 1,3- dimethoxytetramethyldisiloxane , and (ii) a crosslinking gas selected from the group consisting of alcohol, ether, unsaturated hydrocarbon, CO2 and N2 , wherein said alcohol Is selected from the group consisting of C _1-6 alkanols and C _4-12 cycloalkanols, the ether is selected from the group consisting of C _3-20 ethers and C _5-12 cycloalkanol vinyl compounds, and the unsaturated hydrocarbon is A reaction gas comprising a crosslinking gas selected from the group consisting of C _2-4 unsaturated hydrocarbons and C _4-12 alicyclic hydrocarbon unsaturated compounds, and (iii) an inert gas. Introducing into the reaction chamber in which
(b) applying RF power to form a plasma reaction field within the reaction chamber;
(c) controlling the flow rate of the reaction gas and the intensity of the RF power;
A silicon-based insulating film having a hardness of 2.5 GPa or higher and a dielectric constant of 2.8 or lower. A silicon-based insulating film formed on the substrate, the silicon-based insulating film,
(a) (i) A material gas comprising dimethyl dimethyl Toshiki silane or 1,3-dimethoxy-tetramethyldisiloxane or al, (ii) an alcohol, ether, unsaturated hydrocarbon, crosslinked gas selected from the group consisting of CO2 and N2, the The alcohol is selected from the group consisting of C _1-6 alkanol and C _4-12 cycloalkanol, the ether is selected from the group consisting of C _3-20 ether and C _5-12 cycloalkanol vinyl compound, and the unsaturated hydrocarbon Is selected from the group consisting of C _2-4 unsaturated hydrocarbons and C _4-12 alicyclic hydrocarbon unsaturated compounds, a reaction gas comprising a crosslinking gas and (iii) an inert gas. Introducing into the reaction chamber in which the substrate is located;
(b) applying RF power to form a plasma reaction field within the reaction chamber;
(c) controlling the flow rate of the reaction gas and the intensity of the RF power;
A plasma polymerization product obtained by a process comprising: a hardness of 1.0 GPa or higher, a modulus of elasticity of 5.0 GPa or higher, and a dielectric constant of 2.5 or lower However, a silicon-based insulating film.

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