JP2004204061A - Composition for low dielectric film, low dielectric film, and semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prepare a low dielectric film with a low dielectric constant, improved in the stability of the low dielectric constant and with a good formability of a thin film, and to obtain a composition, or the like, for producing the low dielectric film. <P>SOLUTION: The composition for producing the film with the low dielectric constant contains at least two kinds of polar components with mutually different polarity wherein the polarity of a polar component (A) is lower than that of a polar component (B), provided that the ratio of a polar group in all of substituted groups in the molecule of the polar component (A) is A% and the ratio of the polar group in all of substituted groups in the molecule of the polar component (B) is B%, a difference of the ratios (B-A) is ≥10%, the content of the polar component (A) is ≤30 mass% per the total amount of the polar components, and a weight average molecular weight of the polar component (A) is ≤1/4 of a weight average molecular weight of the polar component (B). The low dielectric film is formed by using the composition for the low dielectric film. A semiconductor device comprising a substrate, a plurality of insulating layers and a plurality of circuit layers formed by alternatively laminating on the substrate wherein at least one of the insulating layers is the low dielectric film, is provided. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００６３】
（実施例１）
−低誘電率膜用組成物の調製−
合成例１で合成した有機シリコーン１ｇと、合成例２で合成した有機シリコーン９ｇを、メチルイソブチルケトンに溶解させて、固形分濃度１７．５質量％の低誘電率膜用組成物を調製した。
【００６４】
（比較例１）
−低誘電率膜用組成物の調製−
合成例１で合成した有機シリコーン１０ｇを、メチルイソブチルケトンに溶解させて、固形分濃度１７．５質量％の低誘電率膜用組成物を調製した。
【００６５】
（比較例２）
−低誘電率膜用組成物の調製−
合成例２で合成した有機シリコーン１０ｇを、メチルイソブチルケトンに溶解させて、固形分濃度１７．５質量％の低誘電率膜用組成物を調製した。
【００６６】
（比較例３）
−低誘電率膜用組成物の調製−
合成例１の有機シリコーン５ｇと、合成例２の有機シリコーン５ｇをメチルイソブチルケトンに溶解させて、固形分濃度１７．５質量％の低誘電率膜用組成物を調製した。
なお、比較例３の低誘電率膜用組成物においては、極性が小さい有機シリコーンが全有機シリコーンの５０質量％を占めている。
【００６７】
（比較例４）
−低誘電率膜用組成物の調製−
合成例１の有機シリコーン１ｇと、合成例３の有機シリコーン９ｇとを、メチルイソブチルケトンに溶解させて、固形分濃度１７．５質量％の低誘電率膜用組成物を調製した。
なお、比較例４の低誘電率膜用組成物においては、極性が小さい有機シリコーンの重量平均分子量が極性が大きい有機シリコーンの重量平均分子量の１／４を超えている。
【００６８】
（比較例５）
−低誘電率膜用組成物の調製−
合成例２の有機シリコーン９ｇと、合成例４の有機シリコーン１ｇとを、メチルイソブチルケトンに溶解させて、固形分濃度１７．５質量％の低誘電率膜用組成物を調製した。
なお、比較例５の低誘電率膜用組成物においては、極性基の比率差（Ｂ−Ａ）が１０％未満である。
【００６９】
−低誘電率膜の形成−
次に、得られた実施例１及び比較例１〜５の低誘電率膜用組成物を、シリコンウエハ表面にスピンコート法にて塗布（回転数３０００ｒｐｍ、塗布時間２０秒）し、２００℃で熱処理して溶剤を蒸発させた後、酸素濃度１００ｐｐｍ以下の窒素雰囲気中で、４００℃で３０分間の熱処理を行った。この熱処理により、シロキサン樹脂が架橋し、実施例１及び比較例１〜５の低誘電率膜が形成された。
【００７０】
得られた各低誘電率膜上に、１ｍｍφの金電極を形成し、誘電率を測定した。また、成膜した後、２５℃、５０％ＲＨで５時間放置した後で再び誘電率を測定した。結果を表２に示す。
【００７１】
【表２】

【００７２】
表２の結果から、実施例１の低誘電率膜及び比較例２の低誘電率膜は重量平均分子量が小さい有機シリコーンのみで形成した比較例１の低誘電率膜に比べて、誘電率が低いことが確認できた。これは、比較例１の低誘電率膜の分子がすべて小さいために膜密度が上昇したためと推測される。
【００７３】
また、実施例１及び比較例２の低誘電率膜について、成膜後５時間経過したところで再び誘電率を測定した結果から、実施例１の低誘電率膜の誘電率は２．２５と変化がなかったのに対し、比較例２の低誘電率膜の誘電率は２．６まで上昇した。これは、比較例２の低誘電率膜内のオープンポアが大気中の水分を吸収してしまったためと推測される。
【００７４】
また、比較例３の低誘電率膜の誘電率は２．３１であり、実施例１の低誘電率膜の誘電率は２．３、比較例１の低誘電率膜の誘電率は２．２７、比較例２の低誘電率膜の比誘電率は２．３と大差はなかった。しかし、比較例３の低誘電率膜を成膜後５時間経過したところで再び誘電率を測定したところ、実施例１の低誘電率膜の誘電率は２．３と変化しなかったのに対し、比較例３の低誘電率膜の誘電率は比較例２と同じく２．８まで上昇した。これは、比較例３の低誘電率膜は分子量の大きい分子で構成されている部分が多いため、オープンポアの発生を抑制できず、吸湿したためと推測される。
【００７５】
比較例４の低誘電率膜の誘電率は２．３であったが、成膜後５時間経過したところで誘電率が２．９まで上昇した。
比較例５の低誘電率膜の誘電率は２．２６であったが、成膜後５時間経過したところで誘電率が２．８まで上昇した。
【００７６】
−低誘電率膜上への薄膜の形成−
次に、実施例１及び比較例２の低誘電率膜上にＣＶＤ法により厚さ５０ｎｍのＳｉＮ膜を形成した。
得られた実施例１及び比較例２の低誘電率膜上のＳｉＮ膜について、下記方法により、密着性（被覆性）及び膜厚不均一性（表面荒れ）を評価した。
【００７７】
＜密着性＞
電子顕微鏡による像でＳｉＮ膜の状態を観察した。
＜膜厚不均一性＞
膜厚測定装置「エリプソメータ」（溝尻光学研究所製）を用いて膜厚、表面ラフネスを測定した。
【００７８】
その結果、比較例２の低誘電率膜は、該低誘電率膜内へのＳｉＮ侵入（オープンポアのせいと考えられる）、密着不良（オープンポアからの脱ガスが原因と考えられる）、膜厚不均一（表面荒れが原因と考えられる）が認められた。これに対して、実施例１の低誘電率膜は、ＳｉＮ膜が良好に薄膜形成できており、低誘電率で、しかも誘電率が安定であり、良好な薄膜形成性を備えていることが認められた。
また、実施例１と同様にして比較例５の低誘電率膜の上にＣＶＤ法により厚み５０ｎｍのＳｉＯＣ膜を形成したが、特に密着性の改善効果は得られなかった。
【００７９】
（実施例３）
−多層配線構造を有する半導体集積回路装置の作製−
実施例１の低誘電率膜用組成物を使用して、多層配線構造を有する半導体集積回路装置を作製した。
まず、図４に示したように、従来の通常の工程によって、ｐ型シリコン基板２１に選択酸化法を用いて素子分離酸化膜２２を形成した後、ゲート絶縁膜２３、ゲート電極２４、及び、ＳｉＮ保護膜２６からなるゲート構造体を形成し、サイドウォール２５をマスクとしてＡｓイオンを注入することによってｎ型ソース・ドレイン領域２７を形成した。
なお、図４においては、図示・説明を簡単にするためにＬＤＤ領域の形成工程等は省略する。
【００８０】
次いで、全面に、厚さが、例えば、１μｍのＳｉＯ_２膜２８を堆積させて層間絶縁膜とした後、化学機械研磨（ＣＭＰ）工程において研磨ストッパーとなるＳｉＮ膜２９を、例えば、１００ｎｍの厚さに堆積した。
【００８１】
図４に示したように、ｎ型ソース・ドレイン領域２７に達するビアホールを形成した後、スパッタ法を用いて全面に、厚さが、例えば、５０ｎｍのＴａＮ膜３０を堆積させてバリアメタルとした。次いで、同じく、スパッタ法によってタングステン（Ｗ）を厚く堆積させた後、化学機械研磨（ＣＭＰ）法によってＳｉＮ膜２９が露出するまで研磨することによって、Ｗビア３１を形成した。
【００８２】
次いで、図５に示したように、実施例１の低誘電率膜用組成物をスピーンコータによって塗布し、乾燥工程及び架橋工程を順次行うことによって厚さが、例えば、４５０ｎｍの有機絶縁膜（低誘電率膜）３２を形成した。その後、ＳｉＮ膜３３を、例えば、５０ｎｍの厚さに堆積した。このＳｉＮ膜３３も化学機械研磨（ＣＭＰ）工程におけるストッパーとなる。
このように実施例１の低誘電率膜用組成物を用いると、ＳｉＮ膜が均一な膜厚で良好に成膜できた。
【００８３】
図６に示すように、ＣＦ_４＋ＣＨＦ_３を用いた反応性イオンエッチング（ＲＩＥ）を施すことによってＳｉＮ膜３３をエッチングした後、ＳｉＮ膜３３をマスクとしてＯ_２を用いた反応性イオンエッチング（ＲＩＥ）を施すことによって絶縁膜３２をエッチングしてＷビア３１に達する配線層用溝を形成した。
【００８４】
次いで、スパッタ法を用いて、全面に、例えば、厚さ５０ｎｍのＴａＮ膜３４及び厚さ５０ｎｍのＣｕシード層３５を順次堆積した後、Ｃｕシード層３５をメッキベース層として電解メッキを行うことによってＣｕメッキ層３６を６００ｎｍの厚さに成膜して配線層形成用溝を埋め込んだ。
【００８５】
再び、化学機械研磨（ＣＭＰ）法によってＳｉＮ膜３３が露出するまでＣｕメッキ層３６、Ｃｕシード層３５、及び、ＴａＮ膜３４を研磨して除去することによって、図７に示したように、Ｃｕメッキ層３６とＣｕシード層３５とが一体になったＣｕ埋込配線層３７を形成した。
【００８６】
次いで、図８に示したように、上記絶縁膜３２とＳｉＮ膜３３の製造工程と全く同様にして、厚さが、例えば、４００ｎｍの絶縁膜３８、５０ｎｍのＳｉＮ膜３９、４００ｎｍの絶縁膜４０、及び５０ｎｍのＳｉＮ膜４１を順次成膜した。
その後、ＣＦ_４＋ＣＨＦ_３を用いた反応性イオンエッチング（ＲＩＥ）及びＯ_２を用いた反応性イオンエッチング（ＲＩＥ）を２度繰り返すことによって、絶縁膜３８にＣｕ埋込配線層３７に達するビアホールを形成すると共に、絶縁膜４０に配線層用溝を形成した後、スパッタ法を用いて、全面に、厚さが、例えば、５０ｎｍのＴａＮ膜４２，４３及び５０ｎｍのＣｕシード層（図示せず）を順次堆積させた。次いで、厚さが１４００ｎｍのＣｕメッキ層（図示せず）を成膜して配線層形成用溝及びビアホールを埋め込んだ。
【００８７】
次いで、再び、ＣＭＰ法によってＳｉＮ膜４１が露出するまでＣｕメッキ層、Ｃｕシード層、及び、ＴａＮ膜４２，４３を研磨して除去することによって、Ｃｕメッキ層とＣｕシード層とが一体になったＣｕ埋込配線層４４，４５を形成した。なお、Ｃｕ埋込配線層４４においては配線層とビアとが一体に形成された。
【００８８】
この様な絶縁膜の形成工程、配線層用溝及びビアホールの形成工程、Ｃｕ埋込配線層の形成工程を必要回数だけ繰り返すことによって多層配線構造を有する半導体集積回路装置が得られた。
【００８９】
この実施例３においては、低誘電率膜の誘電率は２．２５程度であるので隣接する配線層に起因する寄生容量を大幅に低減することができ、かつ、誘電率、膜質のバラツキが極めて小さいので、デバイス特性及び信頼性をより向上させることができた。
また、この実施例３においては、バリアメタルとなるＴａＮ膜を厚さ５０ｎｍに堆積させているが、これは、ＴａＮ膜とＣｕシード層との密着性を改善させるためであるので、ＴａＮを更に薄くしても問題がないものである。それによって、Ｃｕ埋込配線層におけるＣｕの比率が増えるので微細化に伴う配線抵抗の上昇を抑制することができた。
なお、実施例３の半導体装置において、実施例２の低誘電率膜を層間絶縁膜として用いた場合にも、同様の良好な結果が得られた。
【００９０】
ここで、本発明の好ましい態様を付記すると、以下の通りである。
（付記１） 互いに極性の異なる有極性成分を２種以上含有してなり、有極性成分（Ａ）の極性が有極性成分（Ｂ）の極性よりも小さく、
該有極性成分（Ａ）の分子中の全置換基における極性基の比率をＡ％とし、該有極性成分（Ｂ）の分子中の全置換基における極性基の比率をＢ％とした時、比率差（Ｂ−Ａ）が１０％以上であり、
該有極性成分（Ａ）の含有量が、有極性成分の総量に対し、３０質量％以下であり、
該有極性成分（Ａ）の重量平均分子量が、有極性成分（Ｂ）の重量平均分子量の１／４以下であることを特徴とする低誘電率膜用組成物。
（付記２） 極性基が、アルコキシ基、水酸基及びカルボキシル基から選択される付記１に記載の低誘電率膜用組成物。
（付記３） 有極性成分（Ａ）の重量平均分子量が２００００未満であり、有極性成分（Ｂ）の重量平均分子量が２００００以上である付記１から２のいずれかに記載の低誘電率膜用組成物。
（付記４） 有極性成分（Ａ）の極性よりも大きく、有極性成分（Ｂ）の極性よりも小さな極性を有する有極性成分（ｃ）を含有する付記１から３のいずれかに記載の低誘電率膜用組成物。
（付記５） 有極性成分の少なくとも１つが、下記一般式（Ｉ）で表されるアルコキシシランを加水分解して得られる有機シリコーンである付記１から４のいずれかに記載の低誘電率膜用組成物。
Ｘ_ｎＳｉ（ＯＲ）_４−ｎ・・・一般式（Ｉ）
（一般式（Ｉ）中、Ｘは、水素原子、フッ素原子、アルキル基若しくはフッ素置換アルキル基、アリール基、又はビニル基を表す。Ｒは、水素原子、アルキル基、アリール基、又はビニル基を表す。ｎは、０〜３の整数を表す。）
（付記６） アルコキシシランが、テトラアルコキシシラン類、モノアルキルトリアルコキシシラン類、アルコキシシラン類及びアミノアルキルアルコキシシラン類から選択される付記５に記載の低誘電率膜用組成物。
（付記７） 付記１から６のいずれかに記載の低誘電率膜用組成物を用いて形成されたことを特徴とする低誘電率膜。
（付記８） 低誘電率膜用組成物が基板上に塗布されて形成された低誘電率膜に対し、焼成、紫外線照射、赤外線照射、電子線照射、Ｘ線照射及び酸素プラズマ照射のいずれかの処理がされてなる付記７に記載の低誘電率膜。
（付記９） 低誘電率膜が、低誘電率膜用組成物をスピンコート法及びディップコート法のいずれかにより基板上に塗布された後、熱処理されて形成される付記８に記載の低誘電率膜。
（付記１０） 熱処理が、１２０〜３５０℃で５〜１０分で行われる付記８から９に記載の低誘電率膜。
（付記１１） 焼成が、不活性雰囲気中、３５０〜４５０℃で行われる付記８から１０のいずれかに記載の低誘電率膜。
（付記１２） 成膜直後における誘電率をＸとし、２５℃、５０％ＲＨで５時間放置後における誘電率をＹとした時、誘電率差（Ｙ−Ｘ）が、−０．１〜＋０．１である付記７から１１のいずれかに記載の低誘電率膜。
（付記１３） 基板と、該基板上に交互に積層して形成した複数の絶縁層及び複数の配線層とを含み、該絶縁層の少なくとも一つが、付記７から１２のいずれかに記載の低誘電率膜であることを特徴とする半導体装置。
（付記１４） 配線層が、アルミニウム、アルミニウム合金、銅、及び銅合金のいずれかで形成された付記１２に記載の半導体装置。
【００９１】
【発明の効果】
本発明によると、従来における問題を解決し、低誘電率であり、低誘電率の安定性に優れ、良好な薄膜形成性を有する低誘電率膜、そのための低誘電率膜用組成物、及び該低誘電率膜を有してなり、高速で信頼性の高い半導体装置を提供することができる。
【図面の簡単な説明】
【図１】図１は、多孔性シリコーン薄膜に形成されたオープンポア及びクローズドポアを説明するための概略断面図である。
【図２】図２は、極性が小さい分子（有極性成分）と極性が大きい分子（有極性成分）とを混合した溶液を基板上に塗布した場合（図２（Ａ））、極性が小さい分子（有極性成分）が表面側に、極性が大きい分子（有極性成分）が基板側に集まる性質（図２（Ｂ））を説明するための模式図である。
【図３】図３は、極性が小さくかつ重量平均分子量が小さい分子（有極性成分）と、極性が大きくかつ重量平均分子量が大きい分子（有極性成分）とを混合した溶液を基板上に塗布した場合（図３（Ａ））、極性が小さくかつ重量平均分子量が小さい分子（有極性成分）が表面側に、極性が大きくかつ重量平均分子量が大きい分子（有極性成分）が基板側に集まる性質（図３（Ｂ））を説明するための模式図である。
【図４】図４は、本発明の一実施例に係る多層配線構造を有する半導体集積回路装置の製造における、ｎ型ソース・ドレイン領域の形成工程を説明するための概略断面図である。
【図５】図５は、本発明の一実施例に係る多層配線構造を有する半導体集積回路装置の製造において、本発明の低誘電率膜を形成した状態を説明するための概略断面図である。
【図６】図６は、本発明の一実施例に係る多層配線構造を有する半導体集積回路装置の製造において、配線層用溝の形成した状態を説明するための概略断面図である。
【図７】図７は、本発明の一実施例に係る多層配線構造を有する半導体集積回路装置の製造において、Ｃｕ埋込配線層を形成した状態を説明するための概略断面図である。
【図８】図８は、本発明の一実施例に係る多層配線構造を有する半導体集積回路装置の製造における、絶縁膜の形成工程、配線層用溝及びビアホールの形成工程、Ｃｕ埋込配線層の形成工程を必要回数繰り返して多層配線構造を有する半導体集積回路装置を形成する状態を説明するための概略断面図である。
【符号の説明】
２１・・・シリコン基板
２２・・・素子間分離膜
２３・・・ゲート絶縁膜
２４・・・ゲート電極
２５・・・サイドウォール
２６・・・ＳｉＮ保護膜
２７・・・ｎ型ソース・ドレイン領域
２８・・・ＳｉＯ_２膜
２９・・・ＳｉＮ膜
３０・・・ＴａＮ膜
３１・・・Ｗビア
３２・・・低誘電率膜
３３・・・ＳｉＮ膜
３４・・・ＴａＮ膜
３５・・・Ｃｕシード層
３６・・・Ｃｕメッキ層
３７・・・Ｃｕ埋込配線層
３８・・・絶縁層
３９・・・ＳｉＮ膜
４０・・・絶縁膜
４１・・・ＳｉＮ膜
４２、４３・・・ＴａＮ膜
４４、４５・・・Ｃｕ埋込配線層[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention has a low dielectric constant, a low dielectric constant film having excellent stability of a low dielectric constant and a good thin film forming property, a composition for a low dielectric constant film therefor, and the low dielectric constant film. The present invention relates to a high-speed and highly reliable semiconductor device.
[0002]
[Prior art]
2. Description of the Related Art In a semiconductor integrated circuit such as an IC or an LSI, an insulating film (usually referred to as an "interlayer insulating film") is stacked between layers of the multilayer wiring. The material of the interlayer insulating film is required to have high heat resistance enough to withstand the manufacturing process of the semiconductor integrated circuit, excellent film strength, and low dielectric constant required for high-speed signal. In the semiconductor integrated circuit, generally, a silicone-based material has been used as a material of the interlayer insulating film. Among them, a spin-on-glass (SOG) -based material (dielectric constant = 3 to 4) is used in many fields because of easy film formation.
[0003]
In recent years, there has been a demand for further lowering the dielectric constant of the interlayer insulating film in a semiconductor device such as the semiconductor integrated circuit, and an insulating film formed of a material having a dielectric constant of less than 3.0, for example, fluorocarbon A thin film formed of a system material, a porous silicone thin film formed by a sol-gel method, and the like have been proposed (for example, see Patent Documents 1 to 3).
[0004]
However, in the case of a thin film formed of the fluorocarbon-based material, there is a problem that adhesion to wiring and other components is poor, and peeling occurs due to stress in the semiconductor device.
On the other hand, in the case of the porous silicone thin film, as shown in FIG. 1, the pores in the porous silicone thin film are connected to each other, and so-called open pores, which are pores opened outside the thin film, easily occur. In addition, there is a problem that the dielectric constant is greatly changed by moisture absorption through the open pores. Further, when a thin film made of metal or other material (for example, SiC, SiN, SiO, etc.) is formed on the porous silicone thin film on which the open pores are formed, the material of the thin film invades the porous silicone thin film from the open pores. However, there is a problem that the performance (dielectric constant, insulating property, etc.) of the porous silicone thin film is changed and deteriorated. Further, since the porous silicone thin film is apt to cause surface roughness (surface irregularities) and degassing from the open pores due to its properties, a thin film made of metal or other materials (eg, SiC, SiN, SiO, etc.) is formed. In this case, there is a problem that the thin film forming property is not sufficient. In this case, in order to suppress the occurrence of the open pores and the surface roughness in the porous silicone thin film and to improve the thin film forming property, it is effective to use a micromolecule as a component of the interlayer material. However, there is a problem that the dielectric constant increases due to the increase in the dielectric constant.
[0005]
On the other hand, (1) a compound that is decomposed by an acid and becomes soluble in an alkaline solution, including (1) a compound having a small molecule polarity and a slow alkali dissolution rate and a component having a large molecule polarity and a fast alkali dissolution rate; A pattern forming method using a photosensitive composition containing a compound that generates an acid upon irradiation with a compound has been proposed (for example, see Patent Document 4). However, here, only the pattern formation using the photosensitive composition is disclosed, and the formation of a low dielectric constant film is not disclosed at all.
[0006]
[Patent Document 1]
JP-A-8-46047
[Patent Document 2]
JP-A-8-64680
[Patent Document 3]
JP-A-9-21797
[Patent Document 4]
Japanese Patent No. 3290793
[0007]
[Problems to be solved by the invention]
An object of the present invention is to solve the conventional problems and achieve the following objects. That is, the present invention has a low dielectric constant, excellent stability of low dielectric constant, a low dielectric constant film having good thin film forming properties, a composition for a low dielectric constant film therefor, and the low dielectric constant film. It is an object of the present invention to provide a high-speed and highly reliable semiconductor device.
[0008]
[Means for Solving the Problems]
Means for solving the above problems are as described in (Appendix 1) to (Appendix 14) described later.
The composition for a low dielectric constant film of the present invention contains two or more polar components having different polarities, and the polarity of the polar component (A) is smaller than the polarity of the polar component (B). When the ratio of polar groups in all the substituents in the molecule of the polar component (A) is A%, and the ratio of the polar groups in all the substituents in the molecule of the polar component (B) is B%, the ratio is as follows. The difference (BA) is 10% or more, the content of the polar component (A) is 30% by mass or less based on the total amount of the polar component, and the weight average of the polar component (A) is The molecular weight is not more than 1/4 of the weight average molecular weight of the polar component (B). When a low dielectric constant film is formed using the composition for a low dielectric constant film, in the low dielectric constant film, the polar component (A) and the polar component (B) are caused by a difference in polarity between each other. As a result, the polar component (A) having a small polarity is unevenly distributed on the surface side, so that the occurrence of the open pores and the surface roughness is effectively suppressed. The low dielectric constant film has a low dielectric constant, is excellent in stability of the low dielectric constant, has a dense and smooth surface, because the density of the low dielectric constant film is reduced in a state having a sufficient amount of closed pores therein. It is excellent in forming a thin film using metal and other materials (for example, SiC, SiN, SiO, etc.).
[0009]
The low dielectric constant film of the present invention is formed using the composition for a low dielectric constant film of the present invention. For this reason, the low dielectric constant film of the present invention has a low dielectric constant, high stability of low dielectric constant, less occurrence of open pores, a dense and smooth film surface, metal and other materials ( For example, SiC, SiN, SiO, etc.) are suitable for use as an interlayer insulating film in a semiconductor device or the like because of their excellent thin film-forming properties.
[0010]
A semiconductor device of the present invention includes a substrate, and a plurality of insulating layers and a plurality of wiring layers formed by being alternately stacked on the substrate. It is a dielectric constant film. The low dielectric constant film is made porous, has a low dielectric constant, is excellent in dielectric constant stability, and contributes to a high response speed. It is particularly suitable for circuits and the like.
In recent years, semiconductor integrated circuits have been highly integrated and have a multilayer wiring structure, wiring widths and intervals have been reduced, and an increase in wiring resistance and an increase in parasitic capacitance between wirings have become problems. The signal propagation speed in the multilayer wiring structure of the semiconductor integrated circuit is determined by the wiring resistance and the parasitic capacitance between the wirings, which are major factors that govern the performance of the device such as the semiconductor integrated circuit. The increase in the wiring resistance and the increase in the parasitic capacitance between the wirings are major problems that must be overcome as the causes of the decrease in the signal propagation speed. In order to improve the signal propagation speed, it is essential to reduce the wiring resistance and the parasitic capacitance (dielectric constant of the insulating film) between the wirings. Although the parasitic capacitance between the wirings can be reduced by making the wiring thinner and reducing the cross-sectional area, when the wiring is made thinner, the wiring resistance increases. That is, since the reduction in the parasitic capacitance between the wirings and the reduction in the wiring resistance have a trade-off relationship, it is not easy to improve the signal propagation speed. However, according to the low dielectric constant film of the present invention, which has a low dielectric constant and is excellent in dielectric constant stability and can contribute to an increase in response speed, the parasitic capacitance between the wirings and the wiring resistance are reduced. And the signal propagation speed can be increased. The semiconductor device of the present invention is particularly suitable for a flash memory, a DRAM, an FRAM, a MOS transistor, and the like, which have high speed and high reliability.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
(Composition for low dielectric constant film)
The composition for a low dielectric constant film of the present invention contains two or more polar components having different polarities from each other, and further contains other components appropriately selected as necessary.
The organic polar component is a component having polarity, and includes at least a polar component (A) and a polar component (B), and further includes a polar component (C) as necessary.
[0012]
In the present invention, it is necessary that the polarity of the polar component (A) is smaller than the polarity of the polar component (B). In this case, when the low dielectric constant film is formed using the composition for a low dielectric constant film, in the low dielectric constant film, the polar component (A) and the polar component (B) are mutually polar. As a result, the polar component (A) having a small polarity is unevenly distributed on the surface side, so that the occurrence of the open pores and the surface roughness is effectively suppressed.
[0013]
The magnitude of the polarities of the polar component (A) and the polar component (B) is determined based on the magnitude (%) of the ratio of the polar group to all the substituents in each molecule. Therefore, the higher the ratio (%) of the polar group to all the substituents in the molecule, the higher the polarity.
Examples of the polar group include an alkoxy group, a hydroxyl group, and a carboxyl group. These polar groups may be the same or different in the polar component. In addition, as said alkoxy group, a methoxy machine, an ethoxy group, a propoxy group, a butoxy group, etc. are mentioned, for example.
[0014]
In the present invention, the ratio of the polar group in all the substituents in the molecule of the polar component (A) is A%, and the ratio of the polar group in all the substituents in the molecule of the polar component (B) is B%. %, The ratio difference (BA) is preferably 10% or more, more preferably 15% or more. Specifically, when the ratio of the polar group in all the substituents in the molecule of the polar component (A) is 30%, the polar group in all the substituents in the molecule of the polar component (B) is Is preferably 40% or more.
If the ratio difference (BA) is less than 10%, the difference in polarity is not sufficient, and open pores and surface roughness tend to easily occur in the low dielectric constant film.
[0015]
The content of the polar component (A) in the composition for a low dielectric constant film is not particularly limited and may be appropriately selected depending on the purpose. For example, the content may be based on the total amount of the polar component. It is preferably at most 30% by mass, more preferably at most 15% by mass.
When the content of the polar component (A) is more than 30% by mass, the resulting film may be densified as a whole and the dielectric constant may be increased.
[0016]
The weight average molecular weight of the polar component (A) is not particularly limited and can be appropriately selected depending on the purpose. For example, it is preferably smaller than the weight average molecular weight of the polar component (B). The weight average molecular weight of the polar component (B) is more preferably 1/4 or less, and particularly preferably 1/5 or less.
When the weight-average molecular weight of the polar component (A) is larger than the weight-average molecular weight of the polar component (B), the obtained low dielectric constant film tends to have an insufficient effect of suppressing open pores and surface roughness. There is.
[0017]
The weight-average molecular weight of the polar component (A) and the weight-average molecular weight of the polar component (B) cannot be unequivocally defined. For example, the weight-average molecular weight of the polar component (A) Preferably, the molecular weight is less than 20,000, and the weight average molecular weight of the polar component (B) is 20,000 or more.
[0018]
The polar component has a polarity larger than the polarity of the polar component (A) and smaller than the polarity of the polar component (B), in addition to the polar component (A) and the polar component (B). It is preferable to contain a polar component (c) having the following formula: In this case, when the low dielectric constant film is formed using the composition for a low dielectric constant film, the polar component (A), the polar component (B), and the polar component Due to the difference in polarity between (C) and the polar component (A), the polar component (A) having a small polarity is unevenly distributed on the surface side, and the polar component (C) having a larger polarity than the polar component (A) inside the polar component (A). Are unevenly distributed, and the polar component (B) having a higher polarity than the polar component (C) is unevenly distributed on the inner side (substrate side). As a result, the occurrence of the open pores and the surface roughness is effectively suppressed. Is done.
[0019]
The weight average molecular weight of the polar component (C) is not particularly limited and may be appropriately selected depending on the intended purpose. For example, the weight average molecular weight of the polar component (A) is larger than that of the polar component (A). It is preferably smaller than the weight average molecular weight of the polar component (B).
[0020]
The polar component is not particularly limited as long as it has polarity, and can be appropriately selected depending on the intended purpose.Examples include organic silicones, synthetic resins such as polynaphthalene, polyborazylene, and the like. At least one is preferably an organic silicone obtained by hydrolyzing an alkoxysilane represented by the following general formula (I).
X_nSi (OR)_4-n... General formula (I)
In the general formula (I), X represents a hydrogen atom, a fluorine atom, an alkyl group or a fluorine-substituted alkyl group, an aryl group, or a vinyl group.
[0021]
The alkyl group is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably one having 1 to 10 carbon atoms, for example, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, -Butyl group, isobutyl group, sec-butyl group, n-hexyl group, isohexyl group, n-heptyl group, n-octyl group, isooctyl group, n-decyl group, isodecyl group, and the like. And a fluorine-substituted alkyl group in which part of a hydrogen atom in the group is substituted with a fluorine atom.
The aryl group is not particularly limited and may be appropriately selected depending on the purpose. Examples thereof include a phenyl group, a tolyl group, a xylyl group, a biphenyl group, a naphthyl group, an anthryl group, and a phenanthryl group. .
R represents a hydrogen atom, the alkyl group, the aryl group, or a vinyl group.
n represents an integer of 0 to 3.
[0022]
The alkoxysilane is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include tetraalkoxysilanes, monoalkyltrialkoxysilanes, alkoxysilanes, and aminoalkylalkoxysilanes. Can be These may be used alone or in combination of two or more.
[0023]
Examples of the tetraalkoxysilanes include, for example, Si (OCH₃)₄, Si (OC₂H₅)₄, Si (OC₃H₇), Si (OC₃H₇ ⁱ)₄, Si (OC₄H₉)₄, And the like.
[0024]
Examples of the monoalkyl trialkoxysilanes include, for example, CH₃Si (OCH₃)₃, CH₃Si (OC₂H₅)₃, CH₃Si (OC₃H₇)₃, CH₃Si (OC₃H₇ ⁱ )₃, CH₃Si (OC₄H₉)₃, C₂H₅Si (OCH₃)₃, C_Two H_Five Si (OC₂H₅)₃, C₂H₅Si (OC₃H₇)₃, C₂H₅Si (OC₃H₇ ⁱ )₃, C₂H₅Si (OC₄H₉)₃ , C₃H₇Si (OCH₃)₃, C₃H₇Si (OC₂H₅)₃, C₃H₇Si (OC₃H₇)₃, C₃H₇Si (OC₃H₇ ⁱ )₃, C₃H₇Si (OC₄H₉)₃, C₃H₇ ⁱ Si (OCH₃)₃, C₃H₇ ⁱ Si (OC₂H₅)₃, C₃H₇ ⁱ Si (OC₃H₇)₃, C₃H₇ ⁱ Si (OC₃H₇ ⁱ )₃, C₃H₇ ⁱ Si (OC₄H₉)₃, C₄H₉Si (OCH₃)₃, C₄H₉Si (OC₂H₅)₃, C₄H₉Si (OC₃H₇)₃, C_FourH₉Si (OC₃H₇ ⁱ )₃, C₄H₉Si (OC₄H₉)₃, And the like.
[0025]
As the alkoxysilanes, for example, HSi (OCH₃)₃, HSi (OC₂H₅)₃, HSi (OC₃H₇)₃, HSi (OC₃H₇ ⁱ )₃, HSi (OC_Four H₉ )₃, And the like.
[0026]
Examples of the aminoalkylalkoxysilanes include, for example, H₂N (CH₂)₃Si (OCH₃)₃, H₂N (CH₂)₃Si (OC₂H₅)₃, H₂N (CH₂)₃Si (OC₃H₇)₃, H₂N (CH₂)₃Si (OC₃H₇ ⁱ)₃, H₂N (CH₂)₃Si (OC₄H₉)₃, H₂N (CH₂)₂NHC₃H₆Si (OCH₃)₃, H₂N (CH₂)₂NHC₃H₆Si (OC₂H₅)₃, H₂N (CH₂)₂NHC₃H₆Si (OC₃H₇)₃, H₂N (CH₂)₂NHC₃H₆Si (OC₃H₇ ⁱ )₃, H₂N (CH₂)₂NHC₃H₆Si (OC₄H₉)₃, H₂N (CH₂)₃(CH₃)₂SiOCH₃, H₂N (CH₂)₃(CH₃)₂SiOC₂H₅, H₂N (CH₂)₃(CH₃)₂SiOC₃H₇, H₂N (CH₂)₃(CH₃)₂SiOC₃H₇ ⁱ , H₂N (CH₂)₃(CH₃)₂SiOC₄H₉, H₂N (CH₂)₃(CH₃)₂SiOCH₃, H₂N (CH₂)₃(CH₃)₂SiOC₂H₅, H₂N (CH₂)₃(CH₃)₂SiOC₃H₇, H₂N (CH₂)₃(CH₃)₂SiOC₃H₇ ⁱ , H₂N (CH₂)₃(CH₃)₂SiOC₄H₉, H₂N (CH₂)₂NH (CH₂)₂NH (CH₂)₂Si (OCH₃)₃, H₂N (CH₂)₂NH (CH₂)₂NH (CH₂)₂Si (OC₂H₅)₃, H₂N (CH₂)₂NH (CH₂)₂NH (CH₂)₂Si (OC₃H₇)₃, H₂N (CH₂)₂NH (CH₂)₂NH (CH₂)₂Si (OC₃H₇ ⁱ)₃, H₂N (CH₂)₂NH (CH₂)₂NH (CH₂)₂Si (OC₄H₉)₃, And the like.
[0027]
The other components are not particularly limited and may be appropriately selected depending on the purpose. Examples thereof include a diluent, a binder resin, and a surfactant.
Examples of the diluent include alcohols such as methanol and ethanol; esters such as acetate; ketones such as cetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; hydrocarbons such as xane, heptane and cyclohexane; Aromatic hydrocarbons such as toluene and xylene; lorinates, glycol acetates such as ethylene glycol monomethyl acetate and ethylene glycol diacetate; hydrocarbons such as hexane; aromatic hydrocarbons such as benzene, toluene, and xylene; And amides such as N, N-methyl-2-pyrrolidone.
[0028]
The organic silicone (alkoxysilane compound polymer or oligomer) obtained by hydrolyzing the alkoxysilane represented by the general formula (I) has a repeating unit structure of —Si—O—Si— bond in the molecule. . In addition, in order to produce the organic silicone, catalysts include inorganic acid catalysts such as hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, and hydrofluoric acid; organic acid catalysts such as oxalic acid, maleic acid, sulfonic acid, and formic acid; ammonia, and trimethylammonium. And other basic catalysts such as trialkylammonium. The organosilicone obtained as described above may be used as it is, or may be used after dissolving the solvent after removing the solvent.
[0029]
The polarity of the polar component is, for example, when the polar component (A) and the polar component (B) are organic silicones obtained by hydrolyzing the alkoxysilane, the remaining alkoxy group and the remaining alkoxy group. Can be controlled by appropriately adjusting the amount of a polar group such as a hydroxyl group formed by hydrolysis.
[0030]
In the composition for a low dielectric constant film of the present invention, the polar component (A) and the polar component (B) are mixed at least. When such a composition for a low dielectric constant film is applied on a substrate, as shown in FIG. 2A, a molecule having a relatively small polarity which should have been present at random immediately after the application (the above-described molecule). As shown in FIG. 2 (B), the polar component (A) moves to the surface of the coating film over time and is unevenly distributed. At this time, the molecule having a relatively large polarity (the polar component (B)) has a property of moving to the substrate side and being unevenly distributed. As a result, when the composition for a low dielectric constant film of the present invention is applied on a substrate, the component having the relatively smaller polarity (the polar component (A)) may be unevenly distributed on the surface layer of the applied film. And only the surface of the coating film can be made dense and smooth, and the occurrence of open pores and surface roughness can be effectively suppressed.On the other hand, since the inside of the coating film has sufficient closed pores, low Density can be increased, and a low dielectric constant can be stably maintained.
[0031]
In the composition for a low dielectric constant film of the present invention, when the weight average molecular weight of the polar component (A) is smaller than the weight average molecular weight of the polar component (B), When the object is applied on the substrate, the polar component (A) and the polar component (B), which existed at random immediately after the application, are replaced with the polar component (B) as shown in FIG. ), The polar component (A) gathers on the surface side of the coating film and the polar component (B) gathers on the substrate side of the coating film over time. When the composition for a low dielectric constant film of the present invention is applied on a substrate by utilizing, the component having a relatively small polarity (the polar component (A)) may be unevenly distributed on the surface layer of the coating film. It is possible to make the surface of the coating film dense and smooth, While it is possible to effectively suppress the raw, since the inside of the coating film has a sufficient closed pores, it is possible to lower density, a low dielectric constant can be stably held.
[0032]
When a low dielectric constant film is formed using the composition for a low dielectric constant film of the present invention, in the obtained low dielectric constant film, the polar component (A) and the polar component (B) have polarities opposite to each other. As a result, the polar component (A) having a small polarity is unevenly distributed on the surface side, so that the occurrence of the open pores and the surface roughness is effectively suppressed. As a result, it has a low dielectric constant, is excellent in stability of low dielectric constant, and has a dense and smooth film surface. Therefore, the stability of dielectric constant is high, and metals and other materials (for example, SiC, SiN, It is excellent in thin film forming properties such as SiO and can be suitably used in various fields, but can be particularly preferably used in the following low dielectric constant films and semiconductor devices of the present invention.
[0033]
(Low dielectric constant film)
The low dielectric constant film of the present invention is formed using the composition for a low dielectric constant film of the present invention. The low dielectric insulating film is formed by baking, ultraviolet irradiation, infrared irradiation, electron beam irradiation, X-ray irradiation and oxygen plasma irradiation on the low dielectric constant film obtained by applying the composition for a low dielectric constant film of the present invention on a substrate. Is formed by performing any one of the above-mentioned treatments, and among these, the above-mentioned baking is preferable in terms of work efficiency, cost, and the like.
[0034]
The method for applying the composition for a low dielectric constant film on a substrate is not particularly limited and can be appropriately selected from known application methods, for example, a spin coating method, a dip coating method, and a kneader coating method. , Curtain coat method, blade coat method and the like. Among these, a spin coating method, a dip coating method, and the like are preferable in terms of coating efficiency and the like.
[0035]
After the application, a solvent or the like can be dried as necessary. The drying temperature is not particularly limited and can be appropriately selected depending on the purpose. However, heat treatment at 120 to 350 ° C ( For example, the solvent is dried for about 5 to 10 minutes.
If the solvent drying temperature is lower than 120 ° C., the solvent drying may be insufficient, and if the solvent drying temperature is higher than 350 ° C., the performance may be changed by oxidation.
[0036]
The firing can be performed at 350 to 450 ° C. (for example, for 30 minutes or more) in an inert atmosphere (for example, in an inert gas having an oxygen concentration of 100 ppm or less). The baking must be performed in an inert atmosphere in order to suppress oxidative decomposition. If the temperature is lower than 350 ° C., there is a concern that degassing from the coating film may occur when wiring is formed. May occur.
[0037]
In the low dielectric constant film of the present invention, when the dielectric constant immediately after the film formation is X and the dielectric constant after standing at 25 ° C. and 50% RH for 5 hours is Y, the dielectric constant difference (Y−X) is as follows: It is preferably -0.1 to +0.1, and more preferably -0.05 to +0.05. As described above, the low dielectric constant film of the present invention has a low dielectric constant and high stability of the low dielectric constant.
The dielectric constant X immediately after the film formation is 3.0 or less, preferably 2.8 or less.
The dielectric constant can be measured by forming a gold electrode on the low dielectric constant film and using a dielectric constant measuring device.
[0038]
The diameter (average diameter) of the pores (voids) formed in the low dielectric constant film is not particularly limited and can be appropriately selected depending on the purpose. Is preferable, and 8 nm or less is more preferable.
Here, the diameter (average diameter) of the holes can be observed and measured with a transmission microscope (TEM).
[0039]
The thickness of the low dielectric constant film is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably about 50 to 3000 nm.
[0040]
Since the low dielectric constant film of the present invention is formed using the composition for a low dielectric constant film of the present invention, the low dielectric constant film has a low dielectric constant, and the stability of the low dielectric constant is high, and the occurrence of open pores is small. It has a dense and smooth film surface, is excellent in forming a thin film of metal or other materials (for example, SiC, SiN, SiO, etc.), and is suitable as an interlayer insulating film in a semiconductor device or the like.
[0041]
(Semiconductor device)
The semiconductor device of the present invention includes a substrate, and a plurality of insulating layers and a plurality of wiring layers alternately formed on the substrate, wherein at least one of the insulating layers is the low dielectric constant film of the present invention. There is no particular limitation other than that the member has a member or the like appropriately selected according to the purpose.
The semiconductor device of the present invention has the low dielectric constant film of the present invention as an interlayer insulating film, resulting in reduced wiring delay, high speed and high reliability, and is suitable for flash memories, DRAMs, FRAMs, MOS transistors, and the like. .
Further, in the semiconductor device of the present invention, since copper does not diffuse in the low dielectric constant film (insulating layer) of the present invention, the material of the metal wiring forming the wiring layer is aluminum, aluminum alloy, copper, and copper alloy. Can be suitably selected from Further, the material of the barrier metal can be suitably selected from titanium, a titanium alloy, tantalum, and a tantalum alloy.
[0042]
Hereinafter, an example of a semiconductor integrated circuit device having a multilayer wiring structure of the present invention will be described with reference to FIGS.
First, as shown in FIG. 4, an element isolation oxide film 22 is formed on a p-type silicon substrate 21 using a selective oxidation method by a conventional process, and then a gate insulating film 23, a gate electrode 24, and a SiN protection film are formed. A gate structure including the film 26 is formed, and As ions are implanted using the sidewalls 25 as a mask to form n-type source / drain regions 27.
In FIG. 4, a process for forming an LDD region and the like are omitted for simplicity of illustration and description.
[0043]
Next, on the entire surface, for example, a 1 μm thick SiO₂After depositing the film 28 to form an interlayer insulating film, a SiN film 29 serving as a polishing stopper is deposited to a thickness of, for example, 100 nm in a chemical mechanical polishing (CMP) step.
[0044]
As shown in FIG. 4, after a via hole reaching the n-type source / drain region 27 is formed, a TaN film 30 having a thickness of, for example, 50 nm is deposited on the entire surface by using a sputtering method to form a barrier metal. Next, similarly, after tungsten (W) is deposited thickly by the sputtering method, the W via 31 is formed by polishing until the SiN film 29 is exposed by the chemical mechanical polishing (CMP) method.
[0045]
Next, as shown in FIG. 5, the composition (coating solution) for a low dielectric constant film of the present invention is applied using a spin coater, and a drying step and a cross-linking step are sequentially performed. An insulating film (low dielectric constant film) 32 was formed. Thereafter, a SiN film 33 was deposited to a thickness of, for example, 50 nm. This SiN film 33 also serves as a stopper in a chemical mechanical polishing (CMP) step. When the composition (coating solution) for a low dielectric constant film of the present invention is used, a SiN film can be formed satisfactorily with a uniform film thickness.
[0046]
Next, as shown in FIG.₄+ CHF₃After the SiN film 33 is etched by performing reactive ion etching (RIE) using GaN, O 2 is etched using the SiN film 33 as a mask.₂The insulating film 32 was etched by performing reactive ion etching (RIE) using, and a trench for a wiring layer reaching the W via 31 was formed.
[0047]
Next, for example, a TaN film 34 having a thickness of 50 nm and a Cu seed layer 35 having a thickness of 50 nm are sequentially deposited on the entire surface by sputtering, and electrolytic plating is performed using the Cu seed layer 35 as a plating base layer to perform Cu plating. The layer 36 was formed to a thickness of 600 nm to fill the wiring layer forming groove.
[0048]
Again, the Cu plating layer 36, the Cu seed layer 35, and the TaN film 34 are polished and removed until the SiN film 33 is exposed by the chemical mechanical polishing (CMP) method, as shown in FIG. A Cu embedded wiring layer 37 in which the 36 and the Cu seed layer 35 were integrated was formed.
[0049]
Next, as shown in FIG. 8, the thickness of the insulating film 38 is, for example, 400 nm, the thickness of the SiN film 39 is 50 nm, the thickness of the insulating film 40 is 400 nm, and the manufacturing process of the insulating film 32 and the SiN film 33 is exactly the same. And a 50 nm SiN film 41 were sequentially formed.
Then, CF₄+ CHF₃Ion etching (RIE) using O2 and O₂Is formed twice by repeating reactive ion etching (RIE) using GaAs to form a via hole reaching the Cu buried wiring layer 37 in the insulating film 38, and forming a wiring layer groove in the insulating film 40, followed by sputtering. On the entire surface, TaN films 42 and 43 having a thickness of, for example, 50 nm and a Cu seed layer (not shown) having a thickness of 50 nm were sequentially deposited. Next, a Cu plating layer (not shown) having a thickness of 1400 nm was formed to fill the wiring layer forming groove and the via hole.
[0050]
Next, the Cu plating layer, the Cu seed layer, and the TaN films 42 and 43 are polished and removed again until the SiN film 41 is exposed by the CMP method, whereby the Cu plating layer and the Cu seed layer are integrated. Cu embedded wiring layers 44 and 45 were formed. In the Cu embedded wiring layer 44, the wiring layer and the via are integrally formed.
[0051]
A semiconductor integrated circuit device (semiconductor device) having a multilayer wiring structure can be obtained by repeating such a process of forming an insulating film, a process of forming a wiring layer groove and a via hole, and a process of forming a Cu buried wiring layer as necessary. Was.
[0052]
In the obtained semiconductor integrated circuit device (semiconductor device) having a multilayer wiring structure, the dielectric constant of the low dielectric constant film is about 2.25, so that the parasitic capacitance caused by the adjacent wiring layer can be significantly reduced. In addition, since variations in dielectric constant and film quality are extremely small, device characteristics and reliability can be further improved. In addition, a TaN film serving as a barrier metal is deposited to a thickness of 50 nm. This is to improve the adhesion between the TaN film and the Cu seed layer. Not something. Thereby, the ratio of Cu in the Cu embedded wiring layer is increased, so that an increase in wiring resistance due to miniaturization can be suppressed.
[0053]
【Example】
Hereinafter, examples of the present invention will be described, but the present invention is not limited to these examples.
[0054]
(Synthesis example 1)
-Synthesis of organic silicone (spherical siloxane resin)-
In 39.6 g of methyl isobutyl ketone, 20.8 g (0.1 mol) of tetraethoxysilane was dissolved. To this, 5.4 g (0.3 mol) of 400 ppm of nitric acid aqueous solution was added dropwise over 10 minutes, and after completion of the addition, an aging reaction was performed for 0.5 hour, and tetraethoxysilane was copolymerized to obtain a spherical siloxane resin (organic resin). Silicone) was synthesized.
Subsequently, 11.8 g (0.1 mol) of trimethylethoxysilane was added dropwise over 10 minutes. After completion of the dropping, an aging reaction was performed for 2 hours to silylate the residual ethoxy group or hydroxyl group of the spherical siloxane resin synthesized previously.
Next, 5 g of magnesium nitrate was added to remove excess water. The reaction solution was removed using a rotary evaporator. Furthermore, lyophilization was performed using 1,4-dioxane.
[0055]
When the weight average molecular weight of the obtained spherical siloxane resin was measured by gel permeation chromatography (GPC), the weight average molecular weight (Mw) was about 15,000. Further, when the amount of the substituent in the spherical siloxane resin was examined using IR and NMR, it was found that the methyl group was about 85%, the ethoxy group was about 10%, the hydroxyl group was about 5%, and the polar group (ethoxy group) was used. And the hydroxyl group) was 15% with respect to the whole spherical siloxane resin.
[0056]
(Synthesis example 2)
-Synthesis of organic silicone (spherical siloxane resin)-
In 39.6 g of methyl isobutyl ketone, 20.8 g (0.1 mol) of tetraethoxysilane was dissolved. To this, 16.2 g (0.9 mol) of nitric acid solution having a concentration of 400 ppm was added dropwise over 10 minutes. After completion of the addition, an aging reaction was performed for 2 hours, and tetraethoxysilane was copolymerized to obtain a spherical siloxane resin (organic silicone). ) Was synthesized.
Subsequently, 5.9 g (0.05 mol) of trimethylethoxysilane was added dropwise over 10 minutes. After completion of the dropwise addition, an aging reaction was performed for 0.5 hour. The residual ethoxy groups or hydroxyl groups of the previously synthesized spherical siloxane resin were silylated.
Next, 5 g of magnesium nitrate was added to remove excess water. The reaction solution was removed using a rotary evaporator. Furthermore, lyophilization was performed using 1,4-dioxane.
[0057]
When the weight average molecular weight (Mw) of the obtained spherical siloxane resin was measured by gel permeation chromatography (GPC), the weight average molecular weight (Mw) was about 80,000. Further, when the amount of the substituent in the spherical siloxane resin was examined by using IR and NMR, the methyl group was about 55%, the ethoxy group was about 35%, the hydroxyl group was about 10%, and the polar group (ethoxy group) was obtained. And the hydroxyl group) was 45% of the total amount of the siloxane resin.
[0058]
(Synthesis example 3)
-Synthesis of organic silicone-
A siloxane resin (organic silicone) was synthesized in the same manner as in Synthesis Example 2 except that the amount of nitric acid was changed to 8.1 g (0.45 mol).
[0059]
The weight average molecular weight (Mw) of the obtained siloxane resin measured by gel permeation chromatography (GPC) was about 35,000. Further, when the amount of the substituent in the siloxane resin was examined using IR and NMR, it was found that the methyl group was about 60%, the ethoxy group was about 30%, the hydroxyl group was about 10%, and the polar groups (ethoxy group and hydroxyl group) were obtained. ) Was 40% of the total amount of the siloxane resin.
[0060]
(Synthesis example 4)
-Synthesis of organic silicone-
A siloxane resin (organic silicone) was synthesized in the same manner as in Synthesis Example 1 except that triethoxysilane was changed to 5.9 g (0.05 mol) in Synthesis Example 1.
[0061]
The weight average molecular weight (Mw) of the obtained siloxane resin measured by gel permeation chromatography (GPC) was about 12,000. Further, when the amount of the substituent in the siloxane resin was examined using IR and NMR, it was found that the methyl group was about 60%, the ethoxy group was about 15%, the hydroxyl group was about 25%, and the polar groups (ethoxy group and hydroxyl group) were obtained. ) Was 40% of the total amount of the siloxane resin.
[0062]
[Table 1]

[0063]
(Example 1)
-Preparation of composition for low dielectric constant film-
1 g of the organic silicone synthesized in Synthesis Example 1 and 9 g of the organic silicone synthesized in Synthesis Example 2 were dissolved in methyl isobutyl ketone to prepare a composition for a low dielectric constant film having a solid content concentration of 17.5% by mass.
[0064]
(Comparative Example 1)
-Preparation of composition for low dielectric constant film-
10 g of the organic silicone synthesized in Synthesis Example 1 was dissolved in methyl isobutyl ketone to prepare a composition for a low dielectric constant film having a solid content of 17.5% by mass.
[0065]
(Comparative Example 2)
-Preparation of composition for low dielectric constant film-
10 g of the organic silicone synthesized in Synthesis Example 2 was dissolved in methyl isobutyl ketone to prepare a composition for a low dielectric constant film having a solid content of 17.5% by mass.
[0066]
(Comparative Example 3)
-Preparation of composition for low dielectric constant film-
5 g of the organic silicone of Synthesis Example 1 and 5 g of the organic silicone of Synthesis Example 2 were dissolved in methyl isobutyl ketone to prepare a composition for a low dielectric constant film having a solid content of 17.5% by mass.
In the low dielectric constant film composition of Comparative Example 3, the organic silicone having a small polarity accounts for 50% by mass of the total organic silicone.
[0067]
(Comparative Example 4)
-Preparation of composition for low dielectric constant film-
1 g of the organic silicone of Synthesis Example 1 and 9 g of the organic silicone of Synthesis Example 3 were dissolved in methyl isobutyl ketone to prepare a composition for a low dielectric constant film having a solid content concentration of 17.5% by mass.
In the composition for a low dielectric constant film of Comparative Example 4, the weight average molecular weight of the organic silicone having a small polarity exceeds １ ／ of the weight average molecular weight of the organic silicone having a large polarity.
[0068]
(Comparative Example 5)
-Preparation of composition for low dielectric constant film-
9 g of the organic silicone of Synthesis Example 2 and 1 g of the organic silicone of Synthesis Example 4 were dissolved in methyl isobutyl ketone to prepare a composition for a low dielectric constant film having a solid content of 17.5% by mass.
In the composition for a low dielectric constant film of Comparative Example 5, the ratio difference (BA) of polar groups is less than 10%.
[0069]
-Formation of low dielectric constant film-
Next, the obtained composition for a low dielectric constant film of Example 1 and Comparative Examples 1 to 5 was applied to the surface of a silicon wafer by a spin coating method (rotation speed: 3000 rpm, application time: 20 seconds). After heat treatment to evaporate the solvent, heat treatment was performed at 400 ° C. for 30 minutes in a nitrogen atmosphere having an oxygen concentration of 100 ppm or less. By this heat treatment, the siloxane resin was crosslinked, and the low dielectric constant films of Example 1 and Comparative Examples 1 to 5 were formed.
[0070]
A gold electrode of 1 mmφ was formed on each of the obtained low dielectric constant films, and the dielectric constant was measured. After the film was formed, it was left at 25 ° C. and 50% RH for 5 hours, and then the dielectric constant was measured again. Table 2 shows the results.
[0071]
[Table 2]

[0072]
From the results shown in Table 2, the low dielectric constant film of Example 1 and the low dielectric constant film of Comparative Example 2 have a lower dielectric constant than the low dielectric constant film of Comparative Example 1 formed only of an organic silicone having a small weight average molecular weight. It was confirmed that it was low. This is presumably because the molecules of the low dielectric constant film of Comparative Example 1 were all small and the film density increased.
[0073]
Also, the dielectric constant of the low dielectric constant film of Example 1 and Comparative Example 2 was changed to 2.25 from the result of measuring the dielectric constant again after 5 hours from the film formation. However, the dielectric constant of the low dielectric constant film of Comparative Example 2 increased to 2.6. This is presumably because the open pores in the low dielectric constant film of Comparative Example 2 absorbed moisture in the atmosphere.
[0074]
The dielectric constant of the low dielectric constant film of Comparative Example 3 was 2.31, the dielectric constant of the low dielectric constant film of Example 1 was 2.3, and the dielectric constant of the low dielectric constant film of Comparative Example 1 was 2.3. 27, the relative dielectric constant of the low dielectric constant film of Comparative Example 2 was 2.3, which was not much different. However, when the dielectric constant was measured again 5 hours after the low dielectric constant film of Comparative Example 3 was formed, the dielectric constant of the low dielectric constant film of Example 1 did not change to 2.3. The dielectric constant of the low dielectric constant film of Comparative Example 3 increased to 2.8 as in Comparative Example 2. This is presumably because the low-dielectric-constant film of Comparative Example 3 had many portions composed of molecules having a large molecular weight, and thus could not suppress the generation of open pores and absorbed moisture.
[0075]
Although the dielectric constant of the low dielectric constant film of Comparative Example 4 was 2.3, the dielectric constant increased to 2.9 five hours after the film formation.
Although the dielectric constant of the low dielectric constant film of Comparative Example 5 was 2.26, the dielectric constant increased to 2.8 five hours after the film formation.
[0076]
-Formation of thin film on low dielectric constant film-
Next, a 50 nm thick SiN film was formed on the low dielectric constant films of Example 1 and Comparative Example 2 by the CVD method.
With respect to the obtained SiN films on the low dielectric constant films of Example 1 and Comparative Example 2, adhesion (coverability) and film thickness nonuniformity (surface roughness) were evaluated by the following methods.
[0077]
<Adhesion>
The state of the SiN film was observed by an image using an electron microscope.
<Thickness non-uniformity>
The film thickness and surface roughness were measured using a film thickness measuring device “Ellipsometer” (manufactured by Mizojiri Optical Laboratory).
[0078]
As a result, the low dielectric constant film of Comparative Example 2 showed that SiN penetrated into the low dielectric constant film (presumed to be due to open pores), poor adhesion (presumed to be caused by degassing from open pores), film Non-uniform thickness (probably due to surface roughness) was observed. On the other hand, the low dielectric constant film of Example 1 has a good thin film SiN film, has a low dielectric constant, has a stable dielectric constant, and has good thin film forming properties. Admitted.
Further, a 50 nm thick SiOC film was formed on the low dielectric constant film of Comparative Example 5 by the CVD method in the same manner as in Example 1, but no particular effect of improving the adhesion was obtained.
[0079]
(Example 3)
-Fabrication of a semiconductor integrated circuit device having a multilayer wiring structure-
Using the composition for a low dielectric constant film of Example 1, a semiconductor integrated circuit device having a multilayer wiring structure was manufactured.
First, as shown in FIG. 4, after a device isolation oxide film 22 is formed on a p-type silicon substrate 21 by using a selective oxidation method by a conventional process, a gate insulating film 23, a gate electrode 24, and A gate structure made of the SiN protective film 26 was formed, and As ions were implanted using the sidewalls 25 as a mask to form n-type source / drain regions 27.
In FIG. 4, a process for forming an LDD region and the like are omitted for simplicity of illustration and description.
[0080]
Next, on the entire surface, for example, a 1 μm thick SiO₂After depositing the film 28 to form an interlayer insulating film, a SiN film 29 serving as a polishing stopper in a chemical mechanical polishing (CMP) step was deposited to a thickness of, for example, 100 nm.
[0081]
As shown in FIG. 4, after a via hole reaching the n-type source / drain region 27 is formed, a TaN film 30 having a thickness of, for example, 50 nm is deposited on the entire surface by a sputtering method to form a barrier metal. . Next, similarly, a tungsten (W) was deposited thickly by sputtering, and then polished by chemical mechanical polishing (CMP) until the SiN film 29 was exposed, thereby forming a W via 31.
[0082]
Next, as shown in FIG. 5, the composition for a low dielectric constant film of Example 1 was applied by a spin coater, and a drying step and a cross-linking step were sequentially performed. (Dielectric constant film) 32 was formed. Thereafter, a SiN film 33 was deposited to a thickness of, for example, 50 nm. This SiN film 33 also serves as a stopper in a chemical mechanical polishing (CMP) step.
As described above, when the composition for a low dielectric constant film of Example 1 was used, a SiN film was successfully formed with a uniform film thickness.
[0083]
As shown in FIG.₄+ CHF₃After the SiN film 33 is etched by performing reactive ion etching (RIE) using GaN, O 2 is etched using the SiN film 33 as a mask.₂The insulating film 32 was etched by performing reactive ion etching (RIE) using, and a trench for a wiring layer reaching the W via 31 was formed.
[0084]
Next, by using a sputtering method, for example, a TaN film 34 having a thickness of 50 nm and a Cu seed layer 35 having a thickness of 50 nm are sequentially deposited on the entire surface, and electrolytic plating is performed by using the Cu seed layer 35 as a plating base layer. The Cu plating layer 36 was formed to a thickness of 600 nm to fill the wiring layer forming groove.
[0085]
Again, the Cu plating layer 36, the Cu seed layer 35, and the TaN film 34 are polished and removed until the SiN film 33 is exposed by the chemical mechanical polishing (CMP) method, as shown in FIG. A Cu embedded wiring layer 37 in which the plating layer 36 and the Cu seed layer 35 were integrated was formed.
[0086]
Then, as shown in FIG. 8, the thickness of the insulating film 38 is, for example, 400 nm, the thickness of the SiN film 39 is 50 nm, and the thickness of the insulating film 40 is 400 nm, in exactly the same manner as the manufacturing process of the insulating film 32 and the SiN film 33. , And a 50 nm SiN film 41 were sequentially formed.
Then, CF₄+ CHF₃Ion etching (RIE) using O2 and O₂Is formed twice by repeating reactive ion etching (RIE) using GaAs to form a via hole reaching the Cu buried wiring layer 37 in the insulating film 38, and forming a wiring layer groove in the insulating film 40, followed by sputtering. On the entire surface, TaN films 42 and 43 having a thickness of, for example, 50 nm and a Cu seed layer (not shown) having a thickness of 50 nm were sequentially deposited. Next, a Cu plating layer (not shown) having a thickness of 1400 nm was formed to fill the wiring layer forming groove and the via hole.
[0087]
Next, the Cu plating layer, the Cu seed layer, and the TaN films 42 and 43 are polished and removed again until the SiN film 41 is exposed by the CMP method, whereby the Cu plating layer and the Cu seed layer are integrated. Cu embedded wiring layers 44 and 45 were formed. In the Cu embedded wiring layer 44, the wiring layer and the via were formed integrally.
[0088]
A semiconductor integrated circuit device having a multilayer wiring structure was obtained by repeating such steps of forming an insulating film, forming a wiring layer groove and a via hole, and forming a Cu embedded wiring layer a required number of times.
[0089]
In the third embodiment, since the dielectric constant of the low dielectric constant film is about 2.25, the parasitic capacitance caused by the adjacent wiring layer can be significantly reduced, and the variation in the dielectric constant and film quality is extremely small. Because of the small size, device characteristics and reliability could be further improved.
In the third embodiment, a TaN film serving as a barrier metal is deposited to a thickness of 50 nm. This is to improve the adhesion between the TaN film and the Cu seed layer. There is no problem with thinning. As a result, the ratio of Cu in the Cu-embedded wiring layer increases, so that an increase in wiring resistance due to miniaturization can be suppressed.
In the semiconductor device of Example 3, similar good results were obtained when the low dielectric constant film of Example 2 was used as an interlayer insulating film.
[0090]
Here, the preferred embodiments of the present invention are as follows.
(Supplementary Note 1) Two or more polar components having different polarities are contained, and the polarity of the polar component (A) is smaller than the polarity of the polar component (B).
When the ratio of the polar group in all the substituents in the molecule of the polar component (A) is A%, and the ratio of the polar group in all the substituents in the molecule of the polar component (B) is B%, The ratio difference (BA) is 10% or more,
The content of the polar component (A) is 30% by mass or less based on the total amount of the polar component;
A composition for a low dielectric constant film, wherein the weight average molecular weight of the polar component (A) is 1/4 or less of the weight average molecular weight of the polar component (B).
(Supplementary Note 2) The composition for a low dielectric constant film according to Supplementary Note 1, wherein the polar group is selected from an alkoxy group, a hydroxyl group, and a carboxyl group.
(Supplementary note 3) The low dielectric constant film according to any one of Supplementary notes 1 and 2, wherein the weight average molecular weight of the polar component (A) is less than 20,000 and the weight average molecular weight of the polar component (B) is 20,000 or more. Composition.
(Supplementary Note 4) The low-temperature light-emitting device according to any one of Supplementary Notes 1 to 3, further including a polar component (c) having a polarity larger than the polarity of the polar component (A) and smaller than the polarity of the polar component (B). Composition for dielectric constant film.
(Supplementary Note 5) For a low dielectric constant film according to any one of Supplementary Notes 1 to 4, wherein at least one of the polar components is an organic silicone obtained by hydrolyzing an alkoxysilane represented by the following general formula (I). Composition.
X_nSi (OR)_4-n... General formula (I)
(In the general formula (I), X represents a hydrogen atom, a fluorine atom, an alkyl group or a fluorine-substituted alkyl group, an aryl group, or a vinyl group. R represents a hydrogen atom, an alkyl group, an aryl group, or a vinyl group. And n represents an integer of 0 to 3.)
(Supplementary Note 6) The composition for a low dielectric constant film according to Supplementary Note 5, wherein the alkoxysilane is selected from tetraalkoxysilanes, monoalkyl trialkoxysilanes, alkoxysilanes, and aminoalkylalkoxysilanes.
(Supplementary Note 7) A low dielectric constant film formed using the composition for a low dielectric constant film according to any one of Supplementary Notes 1 to 6.
(Supplementary Note 8) For the low dielectric constant film formed by applying the composition for a low dielectric constant film on a substrate, any one of baking, ultraviolet irradiation, infrared irradiation, electron beam irradiation, X-ray irradiation, and oxygen plasma irradiation is performed. 8. The low dielectric constant film according to supplementary note 7, which has been treated.
(Supplementary note 9) The low dielectric constant film according to Supplementary note 8, wherein the low dielectric constant film is formed by applying the composition for a low dielectric constant film on a substrate by one of a spin coating method and a dip coating method, and then performing a heat treatment. Rate membrane.
(Supplementary Note 10) The low dielectric constant film according to Supplementary notes 8 to 9, wherein the heat treatment is performed at 120 to 350 ° C for 5 to 10 minutes.
(Supplementary Note 11) The low dielectric constant film according to any one of Supplementary Notes 8 to 10, wherein the firing is performed in an inert atmosphere at 350 to 450 ° C.
(Supplementary Note 12) Assuming that the dielectric constant immediately after the film formation is X and the dielectric constant after standing at 25 ° C. and 50% RH for 5 hours is Y, the dielectric constant difference (Y−X) is −0.1 to +0. 12. The low dielectric constant film according to any one of supplementary notes 7 to 11, wherein
(Supplementary Note 13) The semiconductor device according to any one of Supplementary Notes 7 to 12, including a substrate, and a plurality of insulating layers and a plurality of wiring layers formed by being alternately stacked on the substrate. A semiconductor device characterized by being a dielectric constant film.
(Supplementary Note 14) The semiconductor device according to supplementary note 12, wherein the wiring layer is formed of any one of aluminum, an aluminum alloy, copper, and a copper alloy.
[0091]
【The invention's effect】
According to the present invention, the conventional problems are solved, the dielectric constant is low, the stability of the low dielectric constant is excellent, the low dielectric constant film having a good thin film forming property, the composition for the low dielectric constant film, and A high-speed and highly reliable semiconductor device having the low dielectric constant film can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view for explaining open pores and closed pores formed in a porous silicone thin film.
FIG. 2 shows a case where a solution in which a molecule having a small polarity (polar component) and a molecule having a large polarity (polar component) are mixed is applied onto a substrate (FIG. 2A); FIG. 2B is a schematic diagram for explaining a property (FIG. 2B) in which molecules (polar components) gather on the surface side and molecules (polar components) having high polarity gather on the substrate side.
FIG. 3 is a diagram showing a mixture of a molecule having a small polarity and a small weight-average molecular weight (polar component) and a molecule having a large polarity and a large weight-average molecular weight (a polar component) applied to a substrate. In this case (FIG. 3A), molecules having a small polarity and a small weight average molecular weight (polar component) gather on the surface side, and molecules having a large polarity and a large weight average molecular weight (polar component) gather on the substrate side. FIG. 4 is a schematic diagram for explaining properties (FIG. 3B).
FIG. 4 is a schematic cross-sectional view for explaining a step of forming n-type source / drain regions in manufacturing a semiconductor integrated circuit device having a multilayer wiring structure according to one embodiment of the present invention.
FIG. 5 is a schematic cross-sectional view for explaining a state in which a low dielectric constant film of the present invention is formed in manufacturing a semiconductor integrated circuit device having a multilayer wiring structure according to one embodiment of the present invention. .
FIG. 6 is a schematic cross-sectional view for explaining a state in which a wiring layer groove is formed in the manufacture of a semiconductor integrated circuit device having a multilayer wiring structure according to one embodiment of the present invention.
FIG. 7 is a schematic cross-sectional view for explaining a state in which a Cu embedded wiring layer is formed in manufacturing a semiconductor integrated circuit device having a multilayer wiring structure according to one embodiment of the present invention.
FIG. 8 is a diagram showing a step of forming an insulating film, a step of forming wiring layer grooves and via holes, and a step of forming a Cu embedded wiring layer in the manufacture of a semiconductor integrated circuit device having a multilayer wiring structure according to one embodiment of the present invention. FIG. 5 is a schematic cross-sectional view for illustrating a state in which a semiconductor integrated circuit device having a multilayer wiring structure is formed by repeating the forming step as many times as necessary.
[Explanation of symbols]
21 ... Silicon substrate
22 ・ ・ ・ Element separation film
23 ... Gate insulating film
24 ... Gate electrode
25 ・ ・ ・ Sidewall
26 ... SiN protective film
27 ... n-type source / drain regions
28 ... SiO₂film
29 ... SiN film
30 ... TaN film
31 ・ ・ ・ W via
32 ・ ・ ・ Low dielectric constant film
33 ... SiN film
34 ... TaN film
35 ... Cu seed layer
36 ... Cu plating layer
37 ... Cu embedded wiring layer
38 ... insulating layer
39 ... SiN film
40 ... insulating film
41 ... SiN film
42, 43 ... TaN film
44, 45 ... Cu embedded wiring layer

Claims (5)

It contains two or more polar components having different polarities, and the polarity of the polar component (A) is smaller than that of the polar component (B).
When the ratio of the polar group in all the substituents in the molecule of the polar component (A) is A%, and the ratio of the polar group in all the substituents in the molecule of the polar component (B) is B%, The ratio difference (BA) is 10% or more;
The content of the polar component (A) is 30% by mass or less based on the total amount of the polar component;
A composition for a low dielectric constant film, wherein the weight average molecular weight of the polar component (A) is 1/4 or less of the weight average molecular weight of the polar component (B). The composition for a low dielectric constant film according to claim 1, wherein the polar group is selected from an alkoxy group, a hydroxyl group, and a carboxyl group. 3. The composition for a low dielectric constant film according to claim 1, wherein at least one of the polar components is an organic silicone obtained by hydrolyzing an alkoxysilane represented by the following general formula (I).
X _n Si (OR) _4-n General formula (I)
(In the general formula (I), X represents a hydrogen atom, a fluorine atom, an alkyl group or a fluorine-substituted alkyl group, an aryl group, or a vinyl group. R represents a hydrogen atom, an alkyl group, an aryl group, or a vinyl group. N represents an integer of 0 to 3.) A low dielectric constant film formed using the composition for a low dielectric constant film according to claim 1. A substrate, comprising a plurality of insulating layers and a plurality of wiring layers alternately laminated on the substrate, wherein at least one of the insulating layers is the low dielectric constant film according to claim 4. Semiconductor device.

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