JP2004256479A - Material for insulating film containing organic silane compound, method for producing the same and semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a material for insulating films suitable as an interlaminar insulating material for semiconductor devices, composed of an organic silane compound and formed by a chemical vapor phase growth method, an insulating film formed of the material and a semiconductor device using the insulating film. <P>SOLUTION: The material for insulating films comprises the organic silane compound represented by formula (1) (wherein R<SP>1</SP>, R<SP>2</SP>and R<SP>3</SP>are each a 1-20C hydrocarbon group and R<SP>4</SP>and R<SP>5</SP>are each a hydrogen atom or a 1-20C hydrocarbon group; R<SP>1</SP>, R<SP>2</SP>and R<SP>3</SP>together may form a cyclic structure; m is an integer of 1-3; n is an integer of 0-2; 4-m-n is an integer of 1-3) and is formed by a chemical vapor phase growth method, particularly a plasma-excited chemical vapor phase growth method. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

（式中、Ｒ^１，Ｒ^２，Ｒ^３は、炭素数１〜２０の炭化水素基を表し、Ｒ^４，Ｒ^５は、水素原子または炭素数１〜２０の炭化水素基を表す。Ｒ^１，Ｒ^２，Ｒ^３は、互いに結合し、環状構造を形成してもよい。ｍは、１乃至３の整数、ｎは、０乃至２の整数、４−ｍ−ｎは、１乃至３の整数を表す。）
で示される有機シラン化合物を含んでなる、化学気相成長法により形成される絶縁膜用材料を提供することにある。
【００１８】
以下、本発明の詳細について説明する。
【００１９】
上記一般式（１）において、Ｒ^１，Ｒ^２，Ｒ^３は、炭素数１〜２０の飽和または不飽和炭化水素基であり、直鎖状、分岐鎖状、環状のいずれの構造を有してよい。また、Ｒ^１，Ｒ^２，Ｒ^３が互いに結合したものも本発明の範囲に含まれる。炭素数が２０を超える場合は、対応する有機ハライド等原料の調達が困難となったり、調達できたとしても純度が低い場合がある。
【００２０】
ＣＶＤ装置での安定的使用考慮した場合、炭素数１〜１０の炭化水素基が特に好ましい。炭素数が１０を超えた場合、生成した有機シランの蒸気圧が低くなり、ＰＥＣＶＤ装置での使用が困難となる場合がある。
【００２１】
Ｒ^１，Ｒ^２，Ｒ^３の炭化水素基の例としては、特に限定されるものではないが、炭素数１〜２０、好ましくは炭素数１〜１０のアルキル基、アリール基、アリールアルキル基、アルキルアリール基を挙げることができる。Ｒ^１，Ｒ^２，Ｒ^３は、同一であっても異なっても良い。
【００２２】
Ｒ^１，Ｒ^２，Ｒ^３が互いに結合していない場合の例としては、メチル、エチル、ｎ−プロピル、ｉ−プロピル、ｎ−ブチル、ｉ−ブチル、ｓｅｃ−ブチル、ｔｅｒｔ．−ブチル、ｎ−ペンチル、ｔｅｒｔ．−アミル、ｎ−ヘキシル、シクロヘキシル、フェニル、トルイル等を挙げることができる。
【００２３】
Ｒ^１，Ｒ^２，Ｒ^３が互いに結合した場合の例としては、１−アダマンチルが代表例として挙げられる。
【００２４】
Ｒ^４，Ｒ^５は、水素原子またはＲ^１，Ｒ^２，Ｒ^３と同様の炭化水素基を表し、Ｒ^４どうし，Ｒ^５どうしは、同一でも異なってもよい。
ｍは、１乃至３の整数、ｎは、０乃至２の整数、４−ｍ−ｎは、１乃至３の整数を表す。
【００２５】
一般式（１）で表される有機シラン化合物の具体例としては、
（Ａ） ターシャリーブトキシメチルジメトキシシラン、ターシャリーブトキシメチルジエトキシシラン、ターシャリーブトキシメチルジヒドロキシシラン、ターシャリーブトキシエチルジメトキシシラン、ターシャリーブトキシエチルジエトキシシラン、ターシャリーブトキシエチルジヒドロキシシラン、ターシャリーブトキシフェニルジメトキシシラン、ターシャリーブトキシフェニルジエトキシシラン、ターシャリーブトキシフェニルジヒドロキシシラン等、
（Ｂ） １−アダマンタノキシメチルジメトキシシラン、１−アダマンタノキシメチルジエトキシシラン、１−アダマンタノキシメチルジヒドロキシシラン、１−アダマンタノキシエチルジメトキシシラン、１−アダマンタノキシエチルジエトキシシラン、１−アダマンタノキシエチルジヒドロキシシラン、１−アダマンタノキシフェニルジメトキシシラン、１−アダマンタノキシフェニルジエトキシシラン、１−アダマンタノキシフェニルジヒドロキシシラン等、
（Ｃ） ターシャリーブトキシジメチルヒドロキシシラン、ターシャリーブトキシジメチルメトキシシラン、ターシャリーブトキシジメチルエトキシシラン、ターシャリーブトキシジエチルヒドロキシシラン、ターシャリーブトキシジエチルメトキシシラン、ターシャリーブトキシジエチルエトキシシラン、ターシャリーブトキシジフェニルヒドロキシシラン、ターシャリーブトキシジフェニルメトキシシラン、ターシャリーブトキシジフェニルエトキシシラン等、
（Ｄ） １−アダマンタノキシジメチルヒドロキシシラン、１−アダマンタノキシジメチルメトキシシラン、１−アダマンタノキシジメチルエトキシシラン、１−アダマンタノキシジエチルヒドロキシシラン、１−アダマンタノキシジエチルメトキシシラン、１−アダマンタノキシジエチルエトキシシラン、１−アダマンタノキシジフェニルヒドロキシシラン、１−アダマンタノキシジフェニルメトキシシラン、１−アダマンタノキシジフェニルエトキシシラン等、
（Ｅ） ターシャリーブトキシトリメチルシラン、ターシャリーブトキシトリエチルシラン、ターシャリーブトキシトリフェニルシラン、ターシャリーブトキシジメチルターシャリーブチルシラン等、
（Ｆ） １−アダマンタノキシトリメチルシラン、１−アダマンタノキシトリエチルシラン、１−アダマンタノキシトリフェニルシラン、１−アダマンタノキジメチルターシャリーブチルシラン等
が挙げられる。
【００２６】
上記一般式（１）の有機シランの製造法は、特に限定されるものではないが、例えば、上記一般式（１）においてｍ＝１かつｎ＝０である下記一般式（２）の炭化水素基三置換アルコキシシラン
【００２７】
【化３】

（式中、Ｒ^１，Ｒ^２，Ｒ^３，Ｒ^５は、上記一般式（１）に同じ。）
またはｍ＝１かつｎ＝１である下記一般式（３）の炭化水素基二置換ジアルコキシシランは、
【００２８】
【化４】

（式中、Ｒ^１，Ｒ^２，Ｒ^３，Ｒ^４，Ｒ^５は、上記一般式（１）に同じ。）
下記一般式（４）の炭化水素基置換ハロゲン化シラン、又は、炭化水素基置換アルコキシシランと
【００２９】
【化５】

（式中、Ｒ^４，Ｒ^５は、上記一般式（１）に同じ。Ｘは、弗素原子、塩素原子、臭素原子または沃素原子を表す。ａは、０乃至４の整数、ｂは０乃至４の整数であり、ａとｂは、同時に０でない。）
下記一般式（５）の三級炭素が酸素に直結したアルコキシアルカリ金属塩
【００３０】
【化６】

（式中、Ｒ^１，Ｒ^２，Ｒ^３は、上記一般式（１）に同じ。Ｍ^１は、Ｌｉ，Ｎａ，Ｋを表す。）
を反応させ、製造することができる。
【００３１】
本製造法を採用することにより、副生成物の生成を抑制し、高収率に高純度の一般式（１）で示される有機シラン化合物が得られる。
【００３２】
また、上記一般式（４）の炭化水素基置換ハロゲン化シランまたは炭化水素基置換アルコキシシランと下記一般式（６）の有機リチウム化合物または有機マグネシウム化合物とを更に反応させて得られた、一般式（４）に該当する化合物を使用することも本発明の範囲に入る。
【００３３】
【化７】

（式中、Ｒ^５は、上記一般式（１）に同じ。Ｍ^２は、Ｌｉ，ＭｇＣｌ，ＭｇＢｒ，ＭｇＩを表す。）
製造の際に用いる上記一般式（６）の有機リチウム化合物または有機マグネシウム化合物は、有機ハライドと、金属リチウム粒子または金属マグネシウムとを反応させて製造することができる。
【００３４】
上記一般式（６）の有機リチウム化合物または有機マグネシウム化合物を合成する際の有機ハライドと、金属リチウム粒子または金属マグネシウムとの反応条件は、特に限定されるものではないが、以下にその一例を示す。
【００３５】
使用する金属リチウムとしては、リチウムワイヤー、リチウムリボン、リチウムショット等を用いることができるが、反応の効率面から、５００μｍ以下の粒径を有するリチウム微粒子を用いることが好ましい。
【００３６】
使用する金属マグネシウムとしては、マグネシウムリボン、マグネシウム粒子、マグネシウムパウダー等を用いることができる。
【００３７】
上記の反応に用いる溶媒としては、当該技術分野で使用されるものであれば特に限定されるものでなく、例えば、ｎ−ペンタン、ｉ−ペンタン、ｎ−ヘキサン、シクロヘキサン、ｎ−ヘプタン、ｎ−デカン等の飽和炭化水素類、トルエン、キシレン、デセン−１等の不飽和炭化水素類、ジエチルエーテル、ジプロピルエーテル、ｔｅｒｔ．−ブチルメチルエーテル、ジブチルエーテル、シクロペンチルメチルエーテル等のエーテル類を使用することができる。また、これらの混合溶媒も使用することができる。
【００３８】
上記の反応における反応温度については、生成する有機リチウムまたは有機マグネシウムが分解しない様な温度範囲で行うことが好ましい。通常、工業的に使用されている温度である−１００〜２００℃の範囲、好ましくは、−８５〜１５０℃の範囲で行うことが好ましい。反応の圧力条件は、加圧下、常圧下、減圧下いずれであっても可能である。
【００３９】
合成した有機リチウムまたは有機マグネシウムは、調製の後、そのまま用いることができ、また、未反応の有機ハライドおよび金属リチウム、金属マグネシウム、反応副生成物であるリチウムハライド、マグネシウムハライドを除去した後、使用することもできる。
【００４０】
有機リチウムまたは有機マグネシウムと、上記一般式（４）の炭化水素基置換ハロゲン化シランまたは炭化水素基置換アルコキシシランとの反応条件は、特に限定されるものではないが、以下にその一例を示す。
【００４１】
使用できる反応溶媒は、上記の有機ハライドと金属リチウムまたは金属マグネシウムとの反応の際に用いることができる溶媒と同様のものが使用できる。その反応温度については、使用する有機リチウムまたは有機マグネシウムが分解しない様な温度範囲で行うことが好ましい。通常、工業的に使用されている温度である−１００〜２００℃の範囲、好ましくは−８５〜１５０℃の範囲で行うことが好ましい。反応の圧力条件は、加圧下、常圧下、減圧下いずれであっても可能である。
【００４２】
上記一般式（５）で示される三級炭素が酸素に直結したアルコキシアルカリ金属塩としては、ターシャリーブトキシリチウム、ターシャリーブトキシナトリウム、ターシャリーブトキシカリウム、１−アダマンタノキシリチウム、１−アダマンタノキシナトリウム、１−アダマンタノキシカリウム等を挙げることができる。
【００４３】
上記一般式（５）の三級炭素が酸素に直結したアルコキシアルカリ金属塩と上記一般式（４）の炭化水素基置換ハロゲン化シランまたは炭化水素基置換アルコキシシランとの反応条件は、特に限定されず、上記一般式（６）の有機リチウムまたは有機マグネシウムと、上記一般式（４）の炭化水素基置換ハロゲン化シランまたは炭化水素基置換アルコキシシラン反応条件と同様に行うことができる。
【００４４】
生成した上記一般式（１）で示される有機シラン化合物の精製法については、絶縁膜材料として使用するに有用な水分含有量５０ｐｐｍ未満、ケイ素、炭素、酸素、水素以外の元素であって製造原料に由来する不純物量を１０ｐｐｂ未満とする為に、副生するリチウム塩、マグネシウム塩、アルカリ金属塩を、ガラスフィルター、焼結多孔体等を用いた濾過、常圧もしくは減圧蒸留またはシリカ、アルミナ、高分子ゲルを用いたカラム分離精製等の手段により除去すればよい。この際、必要に応じてこれらの手段を組み合せて使用してもよい。一般の有機合成技術で用いられるような、副生するリチウム塩、マグネシウム塩、アルカリ金属塩を水等により抽出する方法では、最終的に得られる一般式（１）で示される有機シラン化合物中の水分やケイ素、炭素、酸素、水素以外の元素不純物、殊に金属不純物残渣が高くなって、絶縁膜材料として不適当なものとなる場合がある。
【００４５】
また、シラノール構造を含む副生成物が含まれる場合、シラノールの水酸基を水素化ナトリウムまたは水素化カリウム等で、ナトリウム塩またはカリウム塩として沈殿させた後、主生成物である炭化水素基置換アルコキシシランを蒸留により分離生成することができる。
【００４６】
製造に際しては、当該有機金属化合物合成分野での方法に従う。すなわち、脱水および脱酸素された窒素またはアルゴン雰囲気下で行い、使用する溶媒および精製用のカラム充填剤等は、予め脱水操作を施しておくことが好ましい。また、金属残渣およびパーティクル等の不純物も除去しておくことが好ましい。
【００４７】
本発明の一般式（１）で示される有機シラン化合物は、ＰＥＣＶＤ装置により、低誘電率絶縁材料として成膜するに好適な材料である。
【００４８】
これらの材料をＣＶＤで成膜後に、炭素原子とケイ素原子が切断される３５０℃以上の温度で熱処理することで多孔質化した低誘電率絶縁材料を得ることもできる。
【００４９】
本発明の低誘電率材料は、多層配線を用いたＵＬＳＩの製造に好適であり、これを用いた半導体デバイスも本発明の範疇に含有されるものである。
【００５０】
【実施例】
以下に実施例を示すが、本発明は、これらの実施例によって何ら限定されるものではない。
【００５１】
実施例１
［ターシャーリーブチルジメチルクロロシランの合成］
窒素雰囲気下、還流冷却器、滴下濾斗、攪拌装置を備えた３Ｌの四つ口フラスコ反応器にジメチルジクロロシラン２５８．２ｇ（２．００ｍｏｌ）とｎ−ペンタン６００ｍｌを仕込み、０℃に冷却した。滴下濾斗より、２３．７ｗｔ％ターシャリーブチルリチウムのｎ−ペンタン溶液５３９．６ｇ（２．００ｍｏｌ）を１時間で滴下し、更に２時間攪拌した。
【００５２】
反応後、副生した塩化リチウムを濾別除去し、濾液からｎ−ペンタンを留去した後、蒸留により、精製物であるターシャリーブチルジメチルクロロシランを単離した。収量は、２３５．１ｇであり、単離収率は、７８．０％であった。
［ターシャリーブチルジメチルターシャリーブトキシシランの合成］
窒素気流下、還流冷却器、滴下濾斗、攪拌装置を備えた１Ｌの四つ口フラスコ反応器にターシャリーブチルジメチルクロロシラン１５０．７ｇ（１．００ｍｏｌ）とターシャリーブトキシカリウム１３４．７ｇ（１．２０ｍｏｌ）とｎ−ヘキサン５００ｍｌとを仕込み、ｎ−ヘキサン還流条件下、２１時間反応させた。
【００５３】
固体残渣をガラスフィルターにより、濾別し、反応混合物溶液を得た。反応混合物溶液より、ｎ−ヘキサンを留去し、常圧蒸留により、目的物であるターシャリーブチルジメチルターシャリーブトキシシランを単離した。
【００５４】
収量は、１２９．３ｇ（０．６８７ｍｏｌ）であり、収率６８．７％に相当した。
【００５５】
単離したターシャリーブチルジメチルターシャリーブトキシシランを^１Ｈ−ＮＭＲ、^１３Ｃ−ＮＭＲ、ＧＣ−ＭＳで分析した結果は、以下の通りであった。
【００５６】
^１Ｈ−ＮＭＲ；０．１４９ｐｐｍ（ｓ，６Ｈ）、０．９３７ｐｐｍ（ｓ，９Ｈ）、１．３０７ｐｐｍ（ｓ，９Ｈ）
^１３Ｃ−ＮＭＲ；１７．９９ｐｐｍ、２５．８４ｐｐｍ、３２．０５ｐｐｍ
ＧＣ−ＭＳ；Ｍｗ＝１８８、Ｃ_１０Ｈ_２４ＯＳｉ
また、得られたターシャリーブチルジメチルターシャリーブトキシシラン１００ｇ中の水分量並びにカリウムおよびリチウム含有量を、カールフィッシャー水分計およびＩＣＰ−ＭＳ（高周波プラズマ発光−質量分析器、横河アナリティカルシステムズ社製、商品名「ＨＰ４５００」）により測定した結果は、Ｈ_２О＝１１ｐｐｍ、Ｋ＜１０ｐｐｂ、Ｌｉ＜１０ｐｐｂであり、絶縁膜材料として有用なものであった。
【００５７】
比較例１
実施例１のターシャリーブチルジメチルクロロシランとターシャリーブトキシカリウムとの反応後、カリウムクロライドおよび未反応ターシャリーブトキシカリウムを濾別除去せず、水を加えて溶解分液抽出除去したこと以外は、実施例１と同様にしてターシャリーブチルジメチルターシャリーブトキシシランを調製した。
【００５８】
得られたターシャリーブチルジメチルターシャリーブトキシシラン中の水分およびカリウム含有量を、カールフィッシャー水分計およびＩＣＰ−ＭＳにより測定したところ、Ｈ_２О＝１７０ｐｐｍ、Ｋ＝１８ｐｐｂであり、絶縁膜材料としては、不適当なものであった。
【００５９】
実施例２
［メチルジメトキシターシャリーブトキシシランの合成］
窒素気流下、還流冷却器、滴下濾斗、攪拌装置を備えた１Ｌの四つ口フラスコ反応器にメチルトリメトキシシラン２０４．３ｇ（１．５０ｍｏｌ）とターシャリーブトキシカリウム１６８．３ｇ（１．５０ｍｏｌ）とｎ−ヘキサン６００ｍｌとを仕込み、ｎ−ヘキサン還流条件下、１時間反応させた。
【００６０】
固体残渣をガラスフィルターにより、濾別し、反応混合物溶液を得た。反応混合物溶液より、ｎ−ヘキサンを留去し、常圧蒸留により、目的物であるメチルジメトキシターシャリーブトキシシランを単離した。
【００６１】
収量は、１９４．４ｇ（１．０９ｍｏｌ）であり、収率７２．８％に相当した。
【００６２】
単離したメチルジメトキシターシャリーブトキシシランを^１Ｈ−ＮＭＲ、^１３Ｃ−ＮＭＲ、ＧＣ−ＭＳで分析した結果は、以下の通りであった。
【００６３】
^１Ｈ−ＮＭＲ；０．１５１ｐｐｍ（ｓ，３Ｈ）、１．３４７ｐｐｍ（ｓ，９Ｈ）、
３．５４９ｐｐｍ（ｓ，６Ｈ）
^１３Ｃ−ＮＭＲ；０．１９ｐｐｍ、３１．６ｐｐｍ、４９．７ｐｐｍ
ＧＣ−ＭＳ；Ｍｗ＝１７８、Ｃ_７Ｈ_１８Ｏ_３Ｓｉ
また、得られたメチルジメトキシターシャリーブトキシシラン１００ｇ中の水分量並びにカリウム含有量を、カールフィッシャー水分計およびＩＣＰ−ＭＳ（高周波プラズマ発光−質量分析器、横河アナリティカルシステムズ社製、商品名「ＨＰ４５００」）により測定した結果は、Ｈ_２О＝１０ｐｐｍ、Ｋ＜１０ｐｐｂであり、絶縁膜材料として有用なものであった。
【００６４】
実施例３
［メチルジメトキシターシャリーブトキシシランのプラズマ重合成膜］
薄膜の作製には、図１に示すような高周波誘導結合型リモート式プラズマＣＶＤ装置（ＰＥＣＶＤ装置）を使用した。本装置の主たる構成は、石英ガラス製プラズマ源１、成膜チャンバー２、気化器３、真空排気装置４、シリコン基板５、高周波電源６およびマッチングネットワーク７からなり、成膜チャンバー２には、図２に示すような高感度赤外反射吸収分光装置（ＩＲＲＡＳ）が備えてある。このＩＲＲＡＳは、赤外光８を偏光板９で偏光した後、シリコン基板５上に堆積する重合膜に対して８０度の入射角にて照射し、重合膜からの反射光を水銀・カドミウム・テルル半導体赤外センサー１０で検出して、重合膜の成膜状態を確認するためのものである。この装置を用いて、実施例で製造したメチルジメトキシターシャリーブトキシシランのプラズマ重合成膜を以下のように実施した。
【００６５】
成膜チャンバー２を１０^−４Ｐａ以下まで真空排気した後、酸素ガスを５ｓｃｃｍ導入し、チャンバー内の圧力が１０Ｐａになるよう、オリフィスバルブにより排気速度を調節した。その後、酸素ガスを排気し、原料となるターシャリーブチルトリメトキシシランガスを内圧が１０Ｐａとなるまで気化器３を通じて成膜チャンバー２に導入した。内圧が安定した後、プラズマ源１に７５Ｗの高周波を印加し、プラズマを発生させ、成膜チャンバー２内に設置したシリコン基板５上に薄膜を堆積させた。この間、メチルジメトキシターシャリーブトキシシランガスの流量は、５ｓｃｃｍに保たれ、１０分間の成膜を実施した。
【００６６】
成膜中のＩＲＲＡＳでの観測により、ターシャーリーブチル基がケイ素原子に直結した構造を有する酸化ケイ素の重合体が堆積されていることを確認した。
【００６７】
得られたシリコン基板上のプラズマ重合薄膜を電子顕微鏡（ＳＥＭ）、Ｘ線電子分光装置（ＸＰＳ）、赤外吸収分光装置（ＩＲ）により分析した結果を以下に示す。
・膜圧（ＳＥＭ）；３０ｎｍ
・成膜速度；３．０ｎｍ／ｍｉｎ．
・膜組成（ＸＰＳ）；Ｃ＝３７ａｔｏｍ％、Ｏ＝４６ａｔｏｍ％、Ｓｉ＝１７ａｔｏｍ％
・Ｃ／Ｓｉ＝２．１８
・赤外吸収（ＩＲ）；ケイ素原子に直結したターシャリーブチル基（２９５６ｃｍ^−１、１４７９ｃｍ^−１、７２７ｃｍ^−１）、ケイ素原子に直結したメチル基（２８５３ｃｍ^−１、１２７３ｃｍ^−１、７９８ｃｍ^−１）
比較例２
［メチルトリメトキシシランのプラズマ重合成膜］
実施例３においてメチルジメトキシターシャリーブトキシシランに変えて、メチルトリメトキシシランを用い、重合成膜時間を２０分間としたこと以外は、実施例３と同様にしてシリコン基板上にプラズマ重合薄膜を形成し、その分析結果を以下に示す。
・ＩＲＲＡＳ；メチル基がケイ素原子に直結した構造を有する酸化ケイ素の重合体の堆積を確認。
・膜圧（ＳＥＭ）；２２ｎｍ
・成膜速度；１．１ｎｍ／ｍｉｎ．
・膜組成（ＸＰＳ）；Ｃ＝３７ａｔｏｍ％、Ｏ＝４３ａｔｏｍ％、Ｓｉ＝２０ａｔｏｍ％
・Ｃ／Ｓｉ＝１．８５
・赤外吸収（ＩＲ）；ケイ素原子に直結したメチル基（２８５３ｃｍ^−１、１２７３ｃｍ^−１、７９８ｃｍ^−１）、ケイ素原子に直結した水素（２３００ｃｍ^−１付近プロードピーク）、ケイ素原子に直結したヒドロキシ基（３３００ｃｍ^−１付近プロードピーク）
実施例３に比し、成膜速度が遅く、炭素取り込み量も少なく、絶縁膜として不適なケイ素に直結したヒドロキシ基および水素を有するポリマー薄膜ポリマー薄膜であることが確認された。
【００６８】
以上の如く、メチルジメトキシターシャリーブトキシシランのみのプラズマ重合により、絶縁膜として有用なケイ素原子に直結したターシャリーブチル基とメチル基を共に有する高炭素含有量の酸化ケイ素ポリマー薄膜が従来よりも高成膜速度で得られることが明らかとなった。
【００６９】
【発明の効果】
本発明によれば、以下の顕著な効果が奏される。即ち、本発明の第一の効果としては、本発明の構造を有する有機シラン化合物を用いることで、半導体デバイス層間絶縁膜中の低誘電率材料として、低誘電率且つ高機械的強度の材料を提供できることにあり、第二の効果としては、ＰＥＣＶＤ法層間絶縁膜材料として有用な三級炭素原子が酸素素原子に直結したアルコキシ基を有する有機シラン化合物を高純度に効率よく製造できることにある。
【図面の簡単な説明】
【図１】図１は、プラズマＣＶＤ装置（ＰＥＣＶＤ装置）の構成の一例を示す図である。
【図２】図２は、高感度赤外反射吸収分光装置（ＩＲＲＡＳ）の構成の一例を
示す図である。
【符号の説明】
１：石英ガラス製プラズマ源
２：成膜チャンバー
３：気化器
４：真空排気装置
５：シリコン基板
６：高周波電源
７：マッチングネットワーク
８：赤外光
９：偏光板
１０：半導体赤外センサー[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a low dielectric constant interlayer insulating film material used in a multilayer wiring technology in a logic ULSI. In particular, the present invention relates to an insulating film material containing a silane compound for plasma polymerization and its use.
[0002]
[Prior art]
2. Description of the Related Art In manufacturing technology in the field of integrated circuits in the electronics industry, demands for high integration and high speed are increasing. In silicon ULSIs, especially logic ULSIs, the performance of wiring connecting them has become a more important issue than the performance of miniaturized MOSFETs. That is, in order to solve the problem of wiring delay due to the multilayer wiring, reduction of wiring resistance and reduction of capacitance between wirings and between layers are required.
[0003]
For these reasons, it has become essential to introduce copper wiring, which has lower electric resistance and migration resistance, in place of aluminum wiring, which is currently used for most integrated circuits, by sputtering or chemical vapor deposition. , CVD), a process of performing copper plating after seed formation is being put to practical use.
[0004]
There are various proposals for a low dielectric constant interlayer insulating film material. As a conventional technique, silicon dioxide (SiO ₂ ), silicon nitride, and phosphosilicate glass have been used for inorganic materials, and polyimide has been used for organic materials. Proposal of hydrolysis of ethoxysilane monomer, that is, polycondensation to obtain SiO ₂ and use as a coating material called Spin on Glass (inorganic SOG), or polysiloxane obtained by polycondensation of organic alkoxysilane monomer to organic There is a proposal to use it as SOG.
[0005]
There are two methods of forming an insulating film: a coating type in which an insulating film polymer solution is applied and formed by a spin coating method or the like, and a CVD method in which a film is formed by plasma polymerization mainly in a plasma CVD apparatus. .
[0006]
As a proposal of the plasma CVD method, for example, in Patent Document 1, a method of forming a trimethylsilane oxide thin film from trimethylsilane and oxygen by a plasma CVD method, and in Patent Document 2, methyl, ethyl, n-propyl, etc. A method has been proposed in which an alkylsilane thin film is formed from a straight-chain alkyl, vinyl, phenyl or other alkynyl and an alkoxysilane having an aryl group by a plasma CVD method. Insulation films formed from these conventional plasma CVD materials have good adhesion to a copper wiring material, which is a barrier metal and a wiring material, but have the problem of uniformity of the film, and have a problem in film formation speed and relative dielectric constant. In some cases, the rate was insufficient.
[0007]
On the other hand, as a proposal of a coating type, although the uniformity of the film is good, three steps of coating, solvent removal, and heat treatment are required, which is economically disadvantageous compared with the CVD material. In many cases, the problem is the adhesion to the copper wiring material, which is the material, and the uniform application itself of the coating liquid to the substrate structure that has been miniaturized.
[0008]
In addition, a method of using a porous material as a coating material has been proposed in order to realize an Ultra Low-k material having a relative dielectric constant of 2.5 or less, and further, 2.0 or less. Organic or inorganic material matrix readily disperse the thermally decomposed organic component particles in the method of heat treating and pore formation, silicon and oxygen by evaporating SiO ₂ ultrafine particles formed by evaporation in a gas, SiO ₂ than There is a method of forming a fine particle thin film.
[0009]
However, although these porous methods are effective for lowering the dielectric constant, the mechanical strength decreases, making chemical mechanical polishing (CMP) difficult, or increasing the dielectric constant due to absorption of moisture. In some cases, wiring corrosion was caused.
[0010]
Therefore, the market further seeks a well-balanced material that satisfies all required performances such as low dielectric constant, sufficient mechanical strength, adhesion to barrier metal, copper diffusion prevention, plasma ashing resistance, and moisture absorption resistance. As a method of balancing these required performances to some extent, a material having an intermediate characteristic between an organic polymer and an inorganic polymer by increasing the carbon ratio of an organic substituent to silane in an organic silane-based material has been proposed. .
[0011]
For example, in Patent Document 3, a coating solution obtained by hydrolytic polycondensation of a silicon compound having an adamantyl group in the presence of an acidic aqueous solution by a sol-gel method is used. A method for obtaining an insulating film is proposed.
[0012]
However, this material is a coating type material, and still has a problem of the coating type film forming method as described above.
[0013]
[Patent Document 1]
JP 2002-110670 A [Patent Document 2]
Japanese Patent Application Laid-Open No. 11-288931 [Patent Document 3]
Japanese Patent Application Laid-Open No. 2000-302791
[Problems to be solved by the invention]
The present invention has been made in view of the above problems, and an object of the present invention is to provide a novel low dielectric constant material, particularly a low dielectric constant insulating film material containing an alkoxysilane compound suitable for a PECVD apparatus. It is another object of the present invention to provide an insulating film using the same and a semiconductor device including the insulating film.
[0015]
[Means for Solving the Problems]
The present inventors have found that an organic silane compound having an alkoxy group in which a tertiary carbon group is directly bonded to an oxygen atom is suitable as an insulating film, particularly a low dielectric constant interlayer insulating film material for a semiconductor device, The present invention has been completed.
[0016]
That is, the present invention provides the following general formula (1) having at least one alkoxy group in which a tertiary carbon atom and an oxygen atom are directly bonded.
[0017]
Embedded image

(In the formula, R ¹ , R ² , and R ³ represent a hydrocarbon group having 1 to 20 carbon atoms, and R ⁴ and R ⁵ represent a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms. R ¹ , R ² , and R ³ may combine with each other to form a cyclic structure, m is an integer of 1 to 3, n is an integer of 0 to 2, and 4-mn is 1 to 3 Represents an integer.)
An object of the present invention is to provide a material for an insulating film formed by a chemical vapor deposition method, comprising an organic silane compound represented by the formula (1).
[0018]
Hereinafter, details of the present invention will be described.
[0019]
In the general formula (1), R ¹ , R ² , and R ³ are a saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms and have any of a linear, branched, or cyclic structure. May be. Further, those in which R ¹ , R ² and R ³ are bonded to each other are also included in the scope of the present invention. When the number of carbon atoms exceeds 20, it may be difficult to procure the corresponding raw material such as an organic halide, or even if it can be procured, the purity may be low.
[0020]
When stable use in a CVD apparatus is considered, a hydrocarbon group having 1 to 10 carbon atoms is particularly preferable. When the number of carbon atoms exceeds 10, the vapor pressure of the generated organic silane may be low, and it may be difficult to use the organic silane in a PECVD apparatus.
[0021]
Examples of the hydrocarbon group of R ¹ , R ² , and R ³ are not particularly limited, but include an alkyl group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, an aryl group, an arylalkyl group, An alkylaryl group can be mentioned. R ¹ , R ² , and R ³ may be the same or different.
[0022]
Examples in which R ¹ , R ² , and R ³ are not bonded to each other include methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, tert. -Butyl, n-pentyl, tert. -Amyl, n-hexyl, cyclohexyl, phenyl, toluyl and the like.
[0023]
As an example when R ¹ , R ² and R ³ are bonded to each other, 1-adamantyl is a typical example.
[0024]
R ⁴ and R ⁵ represent a hydrogen atom or a hydrocarbon group similar to R ¹ , R ² and R ^3, and R ⁴ and R ⁵ may be the same or different.
m represents an integer of 1 to 3, n represents an integer of 0 to 2, and 4-mn represents an integer of 1 to 3.
[0025]
Specific examples of the organic silane compound represented by the general formula (1) include:
(A) Tertiary butoxymethyldimethoxysilane, tertiary butoxymethyldiethoxysilane, tertiary butoxymethyldihydroxysilane, tertiary butoxyethyldimethoxysilane, tertiary butoxyethyldiethoxysilane, tertiary butoxyethyldihydroxysilane, tertiary butoxyethyl, tertiary butoxy Phenyldimethoxysilane, tert-butoxyphenyldiethoxysilane, tert-butoxyphenyldihydroxysilane, etc.
(B) 1-adamantanoxymethyldimethoxysilane, 1-adamantanoxymethyldiethoxysilane, 1-adamantanoxymethyldihydroxysilane, 1-adamantanoxyethyldimethoxysilane, 1-adamantanoxyethyldiethoxysilane, 1-adamantanoxyethyldihydroxysilane, 1-adamantanoxyphenyldimethoxysilane, 1-adamantanoxyphenyldiethoxysilane, 1-adamantanoxyphenyldihydroxysilane, etc.
(C) tert-butoxydimethylhydroxysilane, tert-butoxydimethylmethoxysilane, tert-butoxydimethylethoxysilane, tert-butoxydiethylhydroxysilane, tert-butoxydiethylmethoxysilane, tert-butoxydiethylethoxysilane, tert-butoxydiphenylhydroxy Silane, tert-butoxydiphenylmethoxysilane, tert-butoxydiphenylethoxysilane, etc.
(D) 1-adamantanoxydimethylhydroxysilane, 1-adamantanoxydimethylmethoxysilane, 1-adamantanoxydimethylethoxysilane, 1-adamantanoxydiethylhydroxysilane, 1-adamantanoxydiethylmethoxysilane, 1- Adamantanoxydiethylethoxysilane, 1-adamantanoxydiphenylhydroxysilane, 1-adamantanoxydiphenylmethoxysilane, 1-adamantanoxydiphenylethoxysilane, etc.
(E) tertiary butoxytrimethylsilane, tertiary butoxytriethylsilane, tertiary butoxytriphenylsilane, tertiary butoxydimethyl tertiary butylsilane, etc.
(F) 1-adamantanoxytrimethylsilane, 1-adamantanoxytriethylsilane, 1-adamantanoxytriphenylsilane, 1-adamantanokidimethyltertiarybutylsilane, and the like.
[0026]
The method for producing the organosilane of the general formula (1) is not particularly limited. For example, a hydrocarbon of the following general formula (2) wherein m = 1 and n = 0 in the general formula (1) is used. Group-substituted alkoxysilane
Embedded image

(In the formula, R ¹ , R ² , R ³ , and R ⁵ are the same as those in the general formula (1).)
Or a hydrocarbon group disubstituted dialkoxysilane of the following general formula (3) wherein m = 1 and n = 1,
[0028]
Embedded image

(In the formula, R ¹ , R ² , R ³ , R ⁴ , and R ⁵ are the same as those in the general formula (1).)
A hydrocarbon group-substituted halogenated silane or a hydrocarbon group-substituted alkoxysilane represented by the following general formula (4):
Embedded image

(In the formula, R ⁴ and R ⁵ are the same as those in the above general formula (1). X represents a fluorine atom, a chlorine atom, a bromine atom or an iodine atom. A is an integer of 0 to 4, and b is 0 to 4. A and b are not 0 at the same time.)
Alkoxy alkali metal salt of the following general formula (5) wherein tertiary carbon is directly connected to oxygen
Embedded image

(In the formula, R ¹ , R ² , and R ³ are the same as those in the general formula (1). M ¹ represents Li, Na, and K.)
Are reacted to produce the compound.
[0031]
By employing this production method, the production of by-products is suppressed, and the organosilane compound represented by the general formula (1) with high yield and high purity can be obtained.
[0032]
Further, a general formula obtained by further reacting a hydrocarbon group-substituted halogenated silane or a hydrocarbon group-substituted alkoxysilane of the above general formula (4) with an organic lithium compound or an organic magnesium compound of the following general formula (6). Use of the compound corresponding to (4) also falls within the scope of the present invention.
[0033]
Embedded image

(In the formula, R ⁵ is the same as in the general formula (1). M ² represents Li, MgCl, MgBr, and MgI.)
The organolithium compound or organomagnesium compound of the above general formula (6) used in the production can be produced by reacting an organic halide with metallic lithium particles or metallic magnesium.
[0034]
The reaction conditions between the organic halide and the metallic lithium particles or metallic magnesium when synthesizing the organolithium compound or organomagnesium compound of the general formula (6) are not particularly limited, but one example is shown below. .
[0035]
As the metal lithium to be used, a lithium wire, a lithium ribbon, a lithium shot, or the like can be used. From the viewpoint of the reaction efficiency, it is preferable to use lithium fine particles having a particle size of 500 μm or less.
[0036]
As the metallic magnesium to be used, a magnesium ribbon, magnesium particles, magnesium powder and the like can be used.
[0037]
The solvent used in the above reaction is not particularly limited as long as it is used in the art, and for example, n-pentane, i-pentane, n-hexane, cyclohexane, n-heptane, n-pentane Saturated hydrocarbons such as decane, unsaturated hydrocarbons such as toluene, xylene and decene-1, diethyl ether, dipropyl ether, tert. Ethers such as -butyl methyl ether, dibutyl ether and cyclopentyl methyl ether can be used. Moreover, these mixed solvents can also be used.
[0038]
The reaction temperature in the above reaction is preferably performed in a temperature range that does not decompose the generated organic lithium or organomagnesium. Usually, it is preferably carried out in a temperature range of −100 to 200 ° C., which is industrially used, and preferably in a range of −85 to 150 ° C. The pressure condition of the reaction can be any of under pressure, normal pressure and reduced pressure.
[0039]
The synthesized organolithium or organomagnesium can be used as it is after preparation, and can be used after removing unreacted organic halide and metallic lithium, metallic magnesium, lithium by-products and magnesium halide as reaction by-products. You can also.
[0040]
The reaction conditions of the organolithium or organomagnesium and the hydrocarbon group-substituted halogenated silane or the hydrocarbon group-substituted alkoxysilane represented by the general formula (4) are not particularly limited, but one example is shown below.
[0041]
As the reaction solvent that can be used, the same solvents as those that can be used in the reaction between the above organic halide and metal lithium or metal magnesium can be used. The reaction temperature is preferably in a temperature range in which the organic lithium or organic magnesium used is not decomposed. Usually, it is preferable to carry out the reaction at a temperature in an industrially used range of -100 to 200C, preferably in a range of -85 to 150C. The pressure condition of the reaction can be any of under pressure, normal pressure and reduced pressure.
[0042]
Examples of the alkoxy alkali metal salt represented by the above general formula (5) in which a tertiary carbon is directly bonded to oxygen include tertiary butoxy lithium, tertiary butoxy sodium, tertiary butoxy potassium, 1-adamantanoxy lithium, and 1-adamantano. And sodium 1-adamantanoxy.
[0043]
The reaction conditions of the alkoxy alkali metal salt of the above general formula (5) in which a tertiary carbon is directly bonded to oxygen and the hydrocarbon group-substituted halogenated silane or the hydrocarbon group-substituted alkoxysilane of the above general formula (4) are particularly limited. Instead, the reaction can be carried out in the same manner as the reaction conditions of the organolithium or organomagnesium of the general formula (6) and the hydrocarbon-substituted halogenated silane or the hydrocarbon-substituted alkoxysilane of the general formula (4).
[0044]
Regarding the method of purifying the produced organosilane compound represented by the above general formula (1), the production raw material is an element other than silicon, carbon, oxygen, and hydrogen, which has a water content of less than 50 ppm useful for use as an insulating film material. In order to reduce the amount of impurities derived from to less than 10 ppb, lithium salts, magnesium salts, and alkali metal salts by-produced are filtered using a glass filter, a sintered porous material, or the like, distillation under normal pressure or reduced pressure, or silica, alumina, It may be removed by means such as column separation and purification using a polymer gel. At this time, these means may be used in combination as needed. In a method of extracting a by-produced lithium salt, magnesium salt, or alkali metal salt with water or the like, which is used in general organic synthesis techniques, the finally obtained organic silane compound represented by the general formula (1) In some cases, moisture, elemental impurities other than silicon, carbon, oxygen, and hydrogen, in particular, metal impurity residues become high, and may become unsuitable as an insulating film material.
[0045]
When a by-product containing a silanol structure is contained, the hydroxyl group of the silanol is precipitated as a sodium salt or a potassium salt with sodium hydride or potassium hydride or the like, and then a hydrocarbon group-substituted alkoxysilane as a main product is obtained. Can be separated and produced by distillation.
[0046]
Upon production, a method in the field of organometallic compound synthesis is followed. That is, it is preferable that the dehydration and deoxygenation be performed in a nitrogen or argon atmosphere, and the solvent to be used and the column filler for purification be subjected to a dehydration operation in advance. It is also preferable to remove impurities such as metal residues and particles.
[0047]
The organosilane compound represented by the general formula (1) of the present invention is a material suitable for forming a film as a low dielectric constant insulating material by a PECVD apparatus.
[0048]
After these materials are formed by CVD, heat treatment is performed at a temperature of 350 ° C. or more at which carbon atoms and silicon atoms are cut, so that a porous low dielectric constant insulating material can be obtained.
[0049]
The low dielectric constant material of the present invention is suitable for manufacturing ULSI using multilayer wiring, and a semiconductor device using the same is also included in the scope of the present invention.
[0050]
【Example】
Examples are shown below, but the present invention is not limited to these examples.
[0051]
Example 1
[Synthesis of tert-butyldimethylchlorosilane]
Under a nitrogen atmosphere, 258.2 g (2.00 mol) of dimethyldichlorosilane and 600 ml of n-pentane were charged into a 3 L four-neck flask reactor equipped with a reflux condenser, a dropping funnel, and a stirrer, and cooled to 0 ° C. . From a dropping funnel, 539.6 g (2.00 mol) of an n-pentane solution of 23.7 wt% tert-butyllithium was added dropwise over 1 hour, and the mixture was further stirred for 2 hours.
[0052]
After the reaction, the by-produced lithium chloride was removed by filtration, n-pentane was distilled off from the filtrate, and the purified tertiary butyldimethylchlorosilane was isolated by distillation. The yield was 235.1 g, and the isolated yield was 78.0%.
[Synthesis of tert-butyl dimethyl tert-butoxysilane]
In a 1 L four-necked flask reactor equipped with a reflux condenser, a dropping funnel and a stirrer under a nitrogen stream, 150.7 g (1.00 mol) of tert-butyldimethylchlorosilane and 134.7 g of potassium tert-butoxy (1. 20 mol) and 500 ml of n-hexane were charged and reacted for 21 hours under n-hexane reflux condition.
[0053]
The solid residue was separated by filtration through a glass filter to obtain a reaction mixture solution. From the reaction mixture solution, n-hexane was distilled off, and tertiary butyl dimethyl tertiary butoxysilane as a target product was isolated by atmospheric distillation.
[0054]
The yield was 129.3 g (0.687 mol), corresponding to a yield of 68.7%.
[0055]
The results of analyzing the isolated tertiary butyl dimethyl tertiary butoxysilane by ¹ H-NMR, ¹³ C-NMR and GC-MS are as follows.
[0056]
^{1 H-NMR; 0.149ppm (s} , 6H), 0.937ppm (s, 9H), 1.307ppm (s, 9H)
¹³ C-NMR; 17.99 ppm, 25.84 ppm, 32.05 ppm
_{GC-MS; Mw = 188,} C 10 H 24 OSi
Further, the water content and the potassium and lithium contents in 100 g of the obtained tertiary butyl dimethyl tertiary butoxysilane were measured by a Karl Fischer moisture meter and ICP-MS (high-frequency plasma emission-mass spectrometer, manufactured by Yokogawa Analytical Systems Co., Ltd.). As a result of measurement under the trade name “HP4500”, H ₂ О = 11 ppm, K <10 ppb, and Li <10 ppb, which were useful as an insulating film material.
[0057]
Comparative Example 1
After the reaction of tert-butyldimethylchlorosilane and potassium tert-butoxide of Example 1, potassium chloride and unreacted tert-butoxypotassium were not removed by filtration, but water was added and the solution was separated and extracted. Tertiary butyl dimethyl tertiary butoxysilane was prepared in the same manner as in Example 1.
[0058]
The content of water and potassium in the obtained tertiary butyl dimethyl tertiary butoxysilane was measured by a Karl Fischer moisture meter and ICP-MS. As a result, H ₂ О = 170 ppm and K = 18 ppb. Was unsuitable.
[0059]
Example 2
[Synthesis of methyldimethoxy tert-butoxysilane]
Under a nitrogen stream, 204.3 g (1.50 mol) of methyltrimethoxysilane and 168.3 g (1.50 mol of potassium tert-butoxy) were placed in a 1 L four-neck flask reactor equipped with a reflux condenser, a dropping funnel and a stirrer. ) And 600 ml of n-hexane were charged and reacted for 1 hour under refluxing conditions of n-hexane.
[0060]
The solid residue was separated by filtration through a glass filter to obtain a reaction mixture solution. From the reaction mixture solution, n-hexane was distilled off, and the desired product, methyldimethoxy-tert-butoxysilane, was isolated by atmospheric distillation.
[0061]
The yield was 194.4 g (1.09 mol), corresponding to a yield of 72.8%.
[0062]
The results of analyzing the isolated methyldimethoxy-tert-butoxysilane by ¹ H-NMR, ¹³ C-NMR, and GC-MS were as follows.
[0063]
^{1 H-NMR; 0.151ppm (s} , 3H), 1.347ppm (s, 9H),
3.549 ppm (s, 6H)
¹³ C-NMR; 0.19 ppm, 31.6 ppm, 49.7 ppm
_{GC-MS; Mw = 178,} C 7 H 18 O 3 Si
Further, the water content and potassium content in 100 g of the obtained methyldimethoxy tert-butoxysilane were measured using a Karl Fischer moisture meter and ICP-MS (high-frequency plasma emission-mass spectrometer, manufactured by Yokogawa Analytical Systems Co., Ltd., trade name “ HP4500 ”), the result was H ₂ О = 10 ppm, K <10 ppb, which was useful as an insulating film material.
[0064]
Example 3
[Plasma polymerization film formation of methyldimethoxy tert-butoxysilane]
For the production of the thin film, a high-frequency inductively coupled remote plasma CVD apparatus (PECVD apparatus) as shown in FIG. 1 was used. The main configuration of the present apparatus comprises a quartz glass plasma source 1, a film forming chamber 2, a vaporizer 3, a vacuum exhaust device 4, a silicon substrate 5, a high-frequency power source 6, and a matching network 7. 2, a high-sensitivity infrared reflection absorption spectroscopy (IRRAS) is provided. In this IRRAS, after the infrared light 8 is polarized by the polarizing plate 9, the polymer film deposited on the silicon substrate 5 is irradiated at an incident angle of 80 degrees, and the reflected light from the polymer film is converted into mercury, cadmium, This is to detect the tellurium semiconductor infrared sensor 10 and confirm the film formation state of the polymer film. Using this apparatus, plasma polymerization film formation of the methyldimethoxy tert-butoxysilane produced in the example was performed as follows.
[0065]
After evacuation of the film forming chamber 2 to 10 ⁻⁴ Pa or less, oxygen gas was introduced at 5 sccm, and the evacuation speed was adjusted by an orifice valve so that the pressure in the chamber became 10 Pa. Thereafter, oxygen gas was exhausted, and tertiary butyl trimethoxysilane gas as a raw material was introduced into the film forming chamber 2 through the vaporizer 3 until the internal pressure became 10 Pa. After the internal pressure was stabilized, a high frequency of 75 W was applied to the plasma source 1 to generate plasma, and a thin film was deposited on the silicon substrate 5 installed in the film forming chamber 2. During this time, the flow rate of the methyldimethoxy tert-butoxysilane gas was kept at 5 sccm, and the film was formed for 10 minutes.
[0066]
Observation by IRRAS during the film formation confirmed that a silicon oxide polymer having a structure in which a tertiary butyl group was directly bonded to a silicon atom was deposited.
[0067]
The results of analyzing the obtained plasma polymerized thin film on the silicon substrate with an electron microscope (SEM), an X-ray electron spectrometer (XPS), and an infrared absorption spectrometer (IR) are shown below.
・ Film pressure (SEM): 30 nm
-Film formation speed: 3.0 nm / min.
Film composition (XPS); C = 37 atom%, O = 46 atom%, Si = 17 atom%
-C / Si = 2.18
And infrared absorption (IR); tertiary butyl group directly attached to silicon atoms ^{(2956cm -1, 1479cm -1, 727cm} -1), methyl group ^{(2853cm -1} directly attached to silicon ^{atoms, 1273cm -1, 798cm} -1 )
Comparative Example 2
[Plasma polymerization film formation of methyltrimethoxysilane]
Example 3 A plasma polymerized thin film was formed on a silicon substrate in the same manner as in Example 3, except that methyltrimethoxysilane was used instead of methyldimethoxytertiarybutoxysilane, and the time for forming a polymer film was 20 minutes. The analysis results are shown below.
-IRRAS: deposition of a polymer of silicon oxide having a structure in which a methyl group is directly connected to a silicon atom was confirmed.
・ Film pressure (SEM): 22 nm
-Film formation rate: 1.1 nm / min.
Film composition (XPS): C = 37 atom%, O = 43 atom%, Si = 20 atom%
C / Si = 1.85
Infrared absorption (IR): methyl group (2853 cm ⁻¹ , 1273 cm ⁻¹ , 798 cm ⁻¹ ) directly bonded to a silicon atom, hydrogen directly bonded to a silicon atom (a broad peak near 2300 cm ⁻¹ ), hydroxy directly bonded to a silicon atom Group (prode peak around 3300cm ^-1 )
Compared with Example 3, it was confirmed that the film was a polymer thin film having a lower film formation rate and a smaller amount of carbon incorporation, and having a hydroxy group and hydrogen directly bonded to silicon, which were unsuitable as an insulating film.
[0068]
As described above, the plasma polymerization of only methyldimethoxy-tert-butoxysilane allows a silicon oxide polymer thin film having a high carbon content having both a tertiary butyl group and a methyl group directly bonded to a silicon atom useful as an insulating film to be higher than before. It was clear that the film could be obtained at a film forming rate.
[0069]
【The invention's effect】
According to the present invention, the following remarkable effects are obtained. That is, as a first effect of the present invention, by using an organic silane compound having the structure of the present invention, a material having a low dielectric constant and a high mechanical strength is used as a low dielectric constant material in a semiconductor device interlayer insulating film. The second effect is that an organic silane compound having an alkoxy group in which a tertiary carbon atom is directly bonded to an oxygen atom, which is useful as a material for an interlayer insulating film by a PECVD method, can be efficiently produced with high purity.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an example of a configuration of a plasma CVD apparatus (PECVD apparatus).
FIG. 2 is a diagram illustrating an example of a configuration of a high-sensitivity infrared reflection absorption spectroscopy (IRRAS).
[Explanation of symbols]
1: Quartz glass plasma source 2: Deposition chamber 3: Vaporizer 4: Vacuum exhaust device 5: Silicon substrate 6: High frequency power supply 7: Matching network 8: Infrared light 9: Polarizing plate 10: Semiconductor infrared sensor

Claims (7)

The following general formula (1) having at least one alkoxy group in which a tertiary carbon atom and an oxygen atom are directly bonded

(In the formula, R ¹ , R ² , and R ³ represent a hydrocarbon group having 1 to 20 carbon atoms, and R ⁴ and R ⁵ represent a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms. R ¹ , R ² , and R ³ may combine with each other to form a cyclic structure, m is an integer of 1 to 3, n is an integer of 0 to 2, and 4-mn is 1 to 3 Represents an integer.)
A material for an insulating film formed by a chemical vapor deposition method, comprising an organic silane compound represented by the formula: The insulating film material according to claim 1, wherein the organic silane compound of the general formula (1) is a tertiary butoxy silane compound. 3. The insulating film according to claim 1, wherein the amount of impurities other than silicon, carbon, oxygen, and hydrogen and derived from a raw material is less than 10 ppb, and the water content is less than 50 ppm. material. The material for an insulating film according to any one of claims 1 to 3, wherein the chemical vapor deposition method is a plasma enhanced chemical vapor deposition (PECVD: Plasma Enhanced Chemical Vapor Deposition). An insulating film formed by a PECVD apparatus using the organic silane compound according to claim 1. 7. An insulating film obtained by heat-treating the insulating film according to claim 6 at a temperature higher than a temperature at which a bond between a carbon atom and a silicon atom is cut. A semiconductor device using the insulating film according to claim 5.

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