JP4304988B2 - Semiconductor device substrate cleaning method - Google Patents

Description

（但し、Ｒ^２は、水酸基、アミノ基、アルコキシ基、ハロゲンにて置換されていてもよいアルキル基を示し、アルキル基に含まれる炭素数（ｍ）は９以上であり、（ｎ）は７以上の数を表す。そして、アルキル基中の炭素数（ｍ）とポリオキシエチレン基中のオキシエチレン基数（ｎ）の比率（ｍ／ｎ）が１〜１．５である。）
成分（Ｂ）：水
成分（Ｃ）：アルカリ
【００３１】
【発明の実施の形態】
以下、本発明を詳細に説明する。本発明の洗浄液は、少なくとも、成分（Ａ）として特定の界面活性剤、成分（Ｂ）として水、成分（Ｃ）としてアルカリ又は有機酸を含有する。
【００３２】
本発明に於いて、成分（Ａ）として使用する界面活性剤は、置換基（フェニル基を除く）を有していてもよい炭化水素基とポリオキシエチレン基とを有し、炭化水素基中の炭素数（ｍ）とポリオキシエチレン基中のオキシエチレン基数（ｎ）の比率（ｍ／ｎ）が１〜１．５であり、炭素数（ｍ）が９以上、オキシエチレン基数（ｎ）が７以上であるエチレンオキサイド型界面活性剤である。
【００３３】
上記の比率（ｍ／ｎ）が１未満の場合は、液中におけるパーティクル除去能力やシリコンの腐食抑制が不十分となる。また、オキシエチレン鎖長増による水への溶解性の低下、廃液処理の負荷も増加する。一方、１．５を超える場合は、アルカリ液中で洗浄時にＯ／Ｗ型のエマルジョンを形成し、界面活性剤が細かい油滴となって析出して白濁してしまい、洗浄性能の低下や油滴の残留などの問題を引き起こす。比率（ｍ／ｎ）は、好ましくは１〜１．４である。
【００３４】
上記の炭素数（ｍ）が９未満の場合は、（ｍ／ｎ）比が前記最適範囲内であってもパーティクル除去性が低下する。また、（ｍ）が大きすぎる場合は、水への溶解性の低下や廃液処理の負荷も増加するので好ましくない。従って、炭素数（ｍ）は、好ましくは９〜１６、更に好ましくは１０〜１４である。ただし、成分（Ａ）を構成する炭化水素基が、置換基として炭化水素基を有する際には、主鎖となる炭化水素基と、置換基である炭化水素基における炭素数の合計数をｍとする。
【００３５】
また、上記の（ｎ）が７未満の場合は、（ｍ／ｎ）比が前記最適範囲内であってもパーティクル除去性が低下する。（ｎ）が大きすぎる場合は、廃液処理の負荷が大きくなり、また、界面活性剤が洗浄液中で分解し易くなる。従って、（ｎ）は、好ましくは７〜１６、更に好ましくは７〜１４である。
【００３６】
本発明で規定する上記のエチレンオキサイド型界面活性剤を使用することにより、洗浄液の濡れ性とパーティクルの除去性の両方が良くなる。上記のエチレンオキサイド型界面活性剤としては、例えば、ポリオキシエチレンアルキルエーテル、ポリオキシエチレン脂肪酸エステル、ポリオキシエチレンアルキルアミン、ポリオキシエチレンアルキルエーテル硫酸塩などが挙げられる。特に、パーティクル汚染の除去性や再付着防止能などの観点から、下記一般式（II）で表されるポリオキシエチレンアルキルエーテルが好ましい。
【００３７】
【化４】

（但し、Ｒ^２は、水酸基、アミノ基、アルコキシ基、ハロゲンにて置換されていてもよいアルキル基を示し、アルキル基に含まれる炭素数（ｍ）は９以上であり、（ｎ）は７以上の数を表す。）
【００３８】
上記のポリオキシエチレンアルキルエーテルの具体例としては、ポリオキシエチレン（ｎ＝８）ノニルエーテル、ポリオキシエチレン（ｎ＝９）デシルエーテル、ポリオキシエチレン（ｎ＝１１）ウンデシルエーテル、ポリオキシエチレン（ｎ＝１０）ラウリルエーテル、ポリオキシエチレン（ｎ＝１１）ラウリルエーテル、ポリオキシエチレン（ｎ＝１０）トリデシルエーテル、ポリオキシエチレン（ｎ＝１２）トリデシルエーテル、ポリオキシエチレン（ｎ＝１１）テトラデシルエーテル、ポリオキシエチレン（ｎ＝１３）テトラデシルエーテル、ポリオキシエチレン（ｎ＝１２）ペンタデシルエーテル、ポリオキシエチレン（ｎ＝１４）ペンタデシルエーテル、ポリオキシエチレン（ｎ＝１２）セチルエーテル、ポリオキシエチレン（ｎ＝１５）セチルエーテル、ポリオキシエチレン（ｎ＝１８）オレイルエーテル等が挙げられる。なお、上記のｎにおける数値は前記の一般式（II）におけるｎを表す。
【００３９】
本発明に於いては、本発明の範囲内であれば（ｍ）及び（ｎ）の異なる複数のエチレンオキサイド型界面活性剤を任意の割合で併用してもよい。更に複数種の界面活性剤を併用する際、全界面活性剤の（ｍ／ｎ）の平均値が１〜１．５、（ｍ）の平均値が９以上、（ｎ）の平均値が７以上の条件を満たせば、各々個別の界面活性剤に於いて（ｍ／ｎ）が１．０未満または１．５を超えていても、また、（ｍ）が９未満、（ｎ）が７未満であってもよい。
【００４０】
洗浄液中における成分（Ａ）の含有量は、通常０．０００１〜１重量％、好ましくは０．０００３〜０．５重量％、更に好ましくは０．００１〜０．１重量％、特に好ましくは０．００１〜０．０５重量％である。成分（Ａ）の濃度が低すぎる場合は、パーティクル汚染除去性能が十分でなく、一方、成分（Ａ）の濃度が高すぎる場合は、パーティクル汚染の除去性能に変化がなく、泡立ちが顕著となり洗浄工程に不向きとなったり、また、廃液を生分解処理する場合の負荷が増大する場合がある。
【００４１】
成分（Ａ）は、通常販売されている形態に於いて１〜数千ｐｐｍ程度のＮａ、Ｋ、Ｆｅ等の金属不純物が含有している場合がある。斯かる場合は、成分（Ａ）が金属汚染源となる。そのため、成分（Ａ）として使用する界面活性剤は、精製して使用するのが好ましい。そして、金属不純物各々の含有量は、通常１０ｐｐｍ以下、好ましくは１ｐｐｍ以下、更に好ましくは０．１ｐｐｍ以下とされる。精製方法としては、例えば、界面活性剤を水で溶解した後、イオン交換樹脂に通液し、樹脂に金属不純物を捕捉させる方法が好適である。
【００４２】
上記の様に精製された成分（Ａ）を使用することで、金属不純物含有量が極めて低減された洗浄液を得ることが出来る。本発明の洗浄液としては、洗浄液中の金属不純物のうち、少なくとも、Ｎａ、Ｍｇ、Ａｌ、Ｋ、Ｃａ、Ｆｅ、Ｃｕ、Ｐｂ、Ｚｎの各々の含有量が、２０ｐｐｂ以下、中でも５ｐｐｂ以下、特に０．１ｐｐｂ以下であることが好ましい。
【００４３】
なお、本発明に於いては、本発明の効果を損ねない範囲で成分（Ａ）以外の界面活性剤を使用してもよい。成分（Ａ）以外の界面活性剤としては、カチオン系界面活性剤、アニオン系界面活性剤およびノニオン系界面活性剤の何れでもよい。中でも、アニオン系界面活性剤やノニオン系界面活性剤を使用することが好まし く、具体的には、例えば、アニオン系界面活性剤としては、炭素数８〜１２のアルキ ルベンゼンスルホン酸およびその塩、炭素数８〜１２のアルキルメチルタウリン酸 およびその塩、炭素数８〜１２のアルキル硫酸エステル及びその塩などが挙げられ る。ノニオン系界面活性剤としては、ポリオキシアルキレンのみからなる界面活 性剤などが挙げられる。
【００４４】
本発明に於いては、成分（Ｂ）として水を使用する。高清浄な基板表面を得たい場合は、通常、脱イオン水、好ましくは超純水が使用される。また、水の電気分解によって得られる電解イオン水、水に水素ガスを溶存させた水素水などを使用することも出来る。
【００４５】
本発明に於いては、成分（Ｃ）としてアルカリ又は有機酸を使用する。すなわち、本発明の洗浄液はアルカリ性洗浄液または酸性洗浄液とされる。
【００４６】
本発明で使用されるアルカリの種類は、特に限定されないが、代表的なアルカリとしては、水酸化アンモニウム（アンモニア水溶液）と有機アルカリが挙げられる。有機アルカリとしては、水酸化第４級アンモニウム、アミン、アミノアルコール等のアミン類が挙げられる。水酸化第４級アンモニウムとしては、水酸基、アルコキシ基、ハロゲンにて置換されていてもよい炭素数１〜４のアルキル基または炭素数１〜４のヒドロキシアルキル基を有するものが好ましく、これらの置換基は全て同一でも異なっていてもよい。
【００４７】
上記の様なアルキル基としては、メチル基、エチル基、プロピル基、ブチル基などの炭素数１〜４の低級アルキル基が挙げられ、ヒドロキシアルキル基としては、ヒドロキシメチル基、ヒドロキシエチル基、ヒドロキシプロピル基、ヒドロキシブチル基などの炭素数１〜４の低級ヒドロキシアルキル基が挙げられる。
【００４８】
上記の置換基を有する水酸化第４級アンモニウムの具体例としては、テトラメチルアモニウムヒドロキシド（ＴＭＡＨ）、テトラエチルアンモニウムヒドロキシド、トリメチル（ヒドロキシエチル）アンモニウムヒドロキシド（通称：コリン）、トリエチル（ヒドロキシエチル）アンモニウムヒドロキシド等が挙げられる。一方、アミン類としては、エチレンジアミン、モノエタノールアミン、トリメタノールアミン等が挙げられる。
【００４９】
上述のアルカリの中では、洗浄効果、金属残留が少ないこと、経済性、洗浄液の安定性などの理由から、水酸化アンモニウム、テトラメチルアンモニウムヒドロキシド（ＴＭＡＨ）、トリメチル（ヒドロキシエチル）アンモニウムヒドロキシド（通称：コリン）が好ましい。これらのアルカリは、単独で使用してもよいし、２種以上を任意の割合で使用してもよい。
【００５０】
洗浄液中のアルカリの濃度は、適宜選択すればよいが、洗浄液のｐＨが９以上のアルカリ性となる濃度であることが好ましい。アルカリ濃度が低すぎてｐＨが高くない場合は、本発明の目的である汚染除去効果が得られない場合がある。一方、ｐＨが高すぎる場合は、ｐＨを高めたことによる効果が得られずに経済的に不利であるばかりか、基板表面がエッチングにより損傷する危険性が増すので好ましくない。従って、アルカリ性洗浄液のｐＨは、好ましくは９〜１３、更に好ましくは１０〜１２．５、特に好ましくは１０．５〜１２である。
【００５１】
本発明で使用される有機酸の種類は、特に限定されないが、有機カルボン酸または有機スルホン酸が好ましい。有機カルボン酸の代表的なものとしては、蟻酸、酢酸、プロピオン酸、酪酸、イソ酪酸、吉草酸、エチルメチル酢酸、トリメチル酢酸、蓚酸、コハク酸、マロン酸、クエン酸、酒石酸、リンゴ酸などが挙げられる。これらの中では、酢酸、プロピオン酸、蓚酸、コハク酸、マロン酸、クエン酸、酒石酸、リンゴ酸の群から選択される１種または２種以上が好ましく、酢酸、蓚酸、クエン酸の群から選択される１種または２種以上が更に好ましい。酢酸は、半導体基板のエッチャント材料などに使用されており、蒸留操作により高純度で金属不純物の少ない物が安価で入手が可能であり、水分蒸発による粉体の発生も起こらない点で最も好ましい。
【００５２】
有機スルホン酸の代表的なものとしては、メタンスルホン酸、エタンスルホン酸、ｎ−プロパンスルホン酸、ｉ−プロパンスルホン酸、ｎ−ブタンスルホン酸、フェニルスルホン酸などが挙げられる。これらの中では、メタンスルホン酸および／またはエタンスルホン酸が好ましく、メタンスルホン酸が特に好ましい。上記の有機酸は、単独で使用してもよいし、２種以上を任意の割合で使用してもよい。
【００５３】
洗浄液中の有機酸の濃度は、適宜選択すればよいが、酸性洗浄液のｐＨが１〜５となる濃度であることが好ましい。有機酸の濃度が低すぎてｐＨが充分低くない場合は、本発明の目的である汚染の除去や付着防止効果が得られない場合がある。一方、濃度が高すぎる場合は、ｐＨを低下させたことによる効果が得られずに経済的に不利で有るばかりか、基板表面の腐食の原因にもなり得るので好ましくない。酸性洗浄液のｐＨは好ましくは２〜３である。
【００５４】
本発明の洗浄液に於いては、錯化剤を含有させると基板表面の金属汚染を更に低減した極めて高度に清浄化された表面が得られるので好ましい。錯化剤としては、従来公知の任意のものを使用できる。錯化剤の種類は、基板表面の汚染レベル、金属の種類、基板表面に要求される清浄度レベル、錯化剤コスト、化学的安定性などから総合的に判断して選択すればよく、例えば、以下の（１）〜（４）にて示すものが挙げられる。
【００５５】
（１）ドナー原子である窒素とカルボキシル基および／またはホスホン酸基を有する化合物：
例えば、グリシン等のアミノ酸類；イミノ２酢酸、ニトリロ３酢酸、エチレンジアミン４酢酸［ＥＤＴＡ］、トランス−１，２−ジアミノシクロヘキサン４酢酸［ＣｙＤＴＡ］、ジエチレントリアミン５酢酸［ＤＴＰＡ］、トリエチレンテトラミン６酢酸［ＴＴＨＡ］等の含窒素カルボン酸類；エチレンジアミンテトラキス（メチレンホスホン酸）［ＥＤＴＰＯ］、ニトリロトリス（メチレンホスホン酸）［ＮＴＰＯ］、プロピレンジアミンテトラ（メチレンホスホン酸）［ＰＤＴＭＰ］等の含窒素ホスホン酸類などが挙げられる。
【００５６】
（２）芳香族炭化水素環を有し且つ芳香族炭化水素環を構成する炭素原子に直接結合したＯＨ基および／またはＯ^-基を２つ以上有する化合物：
例えば、カテコール、レゾルシノール、タイロン等のフェノール類、その誘導体などが挙げられる。
【００５７】
（３）上記（１）及び（２）の構造を併せ持った化合物：
【００５８】
（３−１）エチレンジアミンジオルトヒドロキシフェニル酢酸［ＥＤＤＨＡ］及びその誘導体：
例えば、エチレンジアミンジオルトヒドロキシフェニル酢酸［ＥＤＤＨＡ］、エチレンジアミン−Ｎ，Ｎ’−ビス〔（２−ヒドロキシ−５−メチルフェニル）酢酸〕［ＥＤＤＨＭＡ］、エチレンジアミン−Ｎ，Ｎ’−ビス〔（２−ヒドロキシ−５−クロルフェニル）酢酸〕［ＥＤＤＨＣＡ］、エチレンジアミン−Ｎ，Ｎ’−ビス〔（２−ヒドロキシ−５−スルホフェニル）酢酸〕［ＥＤＤＨＳＡ］等の芳香族含窒素カルボン酸類；エチレンジアミン−Ｎ，Ｎ’−ビス〔（２−ヒドロキシ−５−メチルフェニル）ホスホン酸〕、エチレンジアミン−Ｎ，Ｎ’−ビス〔（２−ヒドロキシ−５−ホスホフェニル）ホスホン酸〕等の芳香族含窒素ホスホン酸類が挙げられる。
【００５９】
（３−２）Ｎ，Ｎ’−ビス（２−ヒドロキシベンジル）エチレンジアミン−Ｎ，Ｎ’−２酢酸［ＨＢＥＤ］及びその誘導体：
例えば、Ｎ，Ｎ’−ビス（２−ヒドロキシベンジル）エチレンジアミン−Ｎ，Ｎ’−２酢酸［ＨＢＥＤ］、Ｎ，Ｎ’−ビス（２−ヒドロキシ−５−メチルベンジル）エチレンジアミン−Ｎ，Ｎ’−２酢酸［ＨＭＢＥＤ］、Ｎ，Ｎ’−ビス（２−ヒドロキシ−５−クロルベンジル）エチレンジアミン−Ｎ，Ｎ’−２酢酸などが挙げられる。
【００６０】
（４）その他：
例えば、エチレンジアミン、８−キノリノール、ｏ−フェナントロリン等のアミン類；ギ酸、酢酸、シュウ酸、酒石酸などのカルボン酸類；フッ化水素酸、塩酸、臭化水素、ヨウ化水素などのハロゲン化水素、それらの塩；リン酸、縮合リン酸などのオキソ酸類、それらの塩などが挙げられる。
【００６１】
上記の錯化剤は、酸の形態のものを使用してもよいし、アンモニウム塩などの塩の形態のものを使用してもよい。
【００６２】
上述した錯化剤の中でも、洗浄効果、化学的安定性などの理由から、エチレンジアミン４酢酸［ＥＤＴＡ］、ジエチレントリアミン５酢酸［ＤＴＰＡ］等の含窒素カルボン酸類；エチレンジアミンテトラキス（メチレンホスホン酸）［ＥＤＴＰＯ］、プロピレンジアミンテトラ（メチレンホスホン酸）［ＰＤＴＭＰ］等の含窒素ホスホン酸類；エチレンジアミンジオルトヒドロキシフェニル酢酸［ＥＤＤＨＡ］及びその誘導体；Ｎ，Ｎ’−ビス（２−ヒドロキシベンジル）エチレンジアミン−Ｎ，Ｎ’−２酢酸［ＨＢＥＤ］が好ましい。
【００６３】
中でも洗浄効果の観点からエレンジアミンジオルトヒドロキシフェニル酢酸［ＥＤＤＨＡ］、エチレンジアミン−Ｎ，Ｎ’−ビス〔（２−ヒドロキシ−５−メチルフェニル）酢酸〕［ＥＤＤＨＭＡ］、ジエチレントリアミン５酢酸［ＤＴＰＡ］、エチレンジアミン４酢酸［ＥＤＴＡ］、プロピレンジアミンテトラ（メチレンホスホン酸）［ＰＤＴＭＰ］が好ましい。上記の錯化剤は、単独で使用してもよいし、２種以上を任意の割合で使用してもよい。
【００６４】
洗浄液中の錯化剤の濃度は、汚染金属不純物の種類と量、基板表面に要求される清浄度レベルによって任意に選択すればよいが、通常１〜１００００ｐｐｍ、好ましくは５〜１０００ｐｐｍ、更に好ましくは１０〜２００ｐｐｍである。錯化剤の濃度が低すぎる場合は、錯化剤による汚染除去や付着防止効果が得られず、高すぎる場合は、濃度増加に見合う効果が得られずに経済的に不利であるばかりか、基板表面に錯化剤が付着し、表面処理後に残留する危険性が増す。
【００６５】
なお、錯化剤は、通常販売されている試薬に於いて１〜数千ｐｐｍ程度のＦｅＡｌ、Ｚｎ等の金属不純物を含有しているので、本発明で使用する錯化剤が金属汚染源となる場合が考えられる。これらの金属は、初期には錯化剤と安定な錯体を形成して存在しているが、表面洗浄液として長時間使用しているうちに錯化剤が分解してくると、遊離し、基板表面に付着する。そのため、本発明で使用する錯化剤は、予め、精製して使用するのが好ましい。そして、含まれる金属不純物各々の含有量は、通常５ｐｐｍ以下、好ましくは１ｐｐｍ以下、更に好ましくは０．１ｐｐｍ以下とされる。精製方法としては、例えば、酸性またはアルカリ性溶液に錯化剤を溶解した後、不溶性不純物をろ過分離して取り除き、再び中和して結晶を析出させ、当該結晶を液と分離する方法が好適である。
【００６６】
また、本発明の洗浄液は、その性能を損なわない範囲に於いて、その他の成分を任意の割合で含有していてもよい。他の成分としては、含硫黄有機化合物（２−メルカプトチアゾリン、２−メルカプトイミダゾリン、２−メルカプトエタノール、チオグリセロール等）、含窒素有機化合物（ベンゾトリアゾール、アルキルベンゾトリアゾール、テトラソール、３−アミノトリアゾール、Ｎ（Ｒ）_３（Ｒは炭素数１〜４のアルキル基）、Ｎ（ＲＯＨ）_３（Ｒは炭素数１〜４のアルキル基）、ウレア、チオウレア等）、水溶性ポリマー（ポリエチレングリコール、ポリビニルアルコール等）、アルキルアルコール系化合物（ＲＯＨ（Ｒは炭素数１〜４のアルキル基））等の防食剤、硫酸、塩酸などの酸、ヒドラジン等の還元剤、水素、アルゴン、窒素などの溶存ガス、フッ酸、フッ化アンモニウム、ＢＨＦ等のドライエッチング後に強固に付着したポリマー等の除去効果が期待できるエッチング促進剤などが挙げられる。
【００６７】
そして、本発明の洗浄液に含有させる他の成分として、オゾン、酸素などの酸化剤も挙げられる。半導体デバイス用基板の洗浄工程に於いて、酸化膜のないシリコン（ベアシリコン）基板表面を洗浄する際には、酸化剤の配合により、基板表面へのエッチングによる表面荒れを抑えることが出来るので好ましい。
【００６８】
ところで、洗浄する基板の表面には、過酸化水素と反応して溶解する金属材料からなる半導体デバイスの配線やデバイス素子電極が露出している場合がある。この様な金属材料としては、例えば、ＣｕやＷなどの遷移金属または遷移金属化合物が挙げられる。この際、洗浄に使用する洗浄液は、実質的に過酸化水素を含有しないことが好ましい。本発明の洗浄液は、従来のＡＰＭ洗浄液とは異なり、過酸化水素を実質的に含有しなくても、この様な金属材料に悪影響を及ぼすことなく、充分な洗浄性能を示す。
【００６９】
なお、本発明の洗浄液に於いて、「実質的に過酸化水素を含有しない」とは、洗浄する基板上の材料、例えばＣｕやＷ等の配線材料や電極材料、及び低誘電率膜に対し、過酸化水素による腐食や変質などの悪影響を生じさせないことを意味する。つまり、これらの材料が、半導体デバイスとした際に、配線や電極などとして充分に機能することを意味する。そのためには、本発明の洗浄液に過酸化水素が含まれない様にし、含有されたとしてもその含有量を少なく抑えるほど好ましい。その含有量は、１０ｐｐｍ以下、好ましくは１ｐｐｍ、更に好ましくは１０ｐｐｂ以下とされる。
【００７０】
本発明の洗浄液は、金属汚染やパーティクル汚染が問題となる半導体、ガラス、金属、セラミックス、樹脂、磁性体、超伝導体などの基板表面の洗浄に使用される。特に高清浄な基板表面が要求される、半導体素子、ディスプレイデバイス用などの半導体デバイス用基板を製造する工程における、半導体デバイス用基板表面の洗浄に好適に使用される。これらの基板の表面には、配線、電極などが存在していてもよい。配線や電極の材料としては、Ｓｉ、Ｇｅ、ＧａＡｓ等の半導体材料；ＳｉＯ₂、窒化シリコン、ガラス、低誘電率材料、酸化アルミニウム、遷移金属酸化物（酸化チタン、酸化タンタル、酸化ハフニウム、酸化ジルコニウム等）、（Ｂａ、Ｓｒ）ＴｉＯ₃（ＢＳＴ）、ポリイミド、有機熱硬化性樹脂などの絶縁材料；Ｗ、Ｃｕ、Ａｌ等の金属またはこれらの合金、シリサイド、窒化物などが挙げられる。低誘電率材料とは、比誘電率が３．５以下である材料の総称である。因に、ＳｉＯ₂の比誘電率は３．８〜３．９である。
【００７１】
特に、本発明の洗浄液は、表面に遷移金属または遷移金属化合物を有する半導体デバイス用基板の洗浄に好適に使用される。遷移金属としては、Ｗ、Ｃｕ、Ｔｉ、Ｃｒ、Ｃｏ、Ｚｒ、Ｈｆ、Ｍｏ、Ｒｕ、Ａｕ、Ｐｔ、Ａｇ等が挙げられ、遷移金属化合物としては、これらの遷移金属のチッ化物、酸化物、シリサイド等が挙げられる。これらの中では、Ｗ及び／又はＣｕが好ましい。
【００７２】
表面にタングステンを有する基板の洗浄を行う工程としては、タングステンをゲート電極材料として使用した場合の、ゲート電極とシリコン等を有する基板表面の洗浄が挙げられる。具体的には、半導体デバイスにタングステン膜を形成した後の洗浄工程、特に、タングステン膜をドライエッチングした後の洗浄工程、その後にシリコン露出部にイオン注入した後の洗浄工程が挙げられる。
【００７３】
本発明の洗浄液を使用すれば、超音波照射やブラシスクラブを行わなくても、パーティクルや金属の除去を行なうことが出来る。従って、本発明の洗浄液は、超音波洗浄やブラシスクラブを行うと壊れてしまう恐れが大きい、極微細な（例えば、ゲート電極の幅が０．１５μｍ程度の）ゲート電極をタングステンで形成した場合の、ゲート電極および基板表面の洗浄に好適である。
【００７４】
表面にＣｕを有する基板の洗浄を行う工程としては、Ｃｕを配線材料として使用した場合の、Ｃｕ配線と層間絶縁膜などを有する基板表面の洗浄が挙げられる。具体的には、半導体デバイスにＣｕ膜を形成した後の洗浄工程、特にＣｕ膜に対してＣＭＰ（Chemical Mechanical Polishing）を行った後の洗浄工程、配線上の層間絶縁膜にドライエッチングによりホールを開けた後の洗浄工程が挙げられる。
【００７５】
また、本発明の洗浄液は、表面に層間絶縁膜材料となる低誘電率材料を有する半導体デバイス用基板の洗浄にも好適に使用される。低誘電率材料としては、有機ポリマー材料、無機ポリマー（シロキサン系）材料、多孔質（ポーラス）材料と、大きく３つに分けられる。有機ポリマー材料としては、Polyimide、ＢＣＢ(Benzocyclobutene)、Flare(Honeywell社)、SiLK(Dow Chemical)等が挙げられ、無機ポリマー材料としては、ＦＳＧ(Fluorinated silicate glass)、BLACK DIAMOND(Applied Materials)、Aurora(日本ASM)等が挙げられる。
【００７６】
本発明の洗浄液は、上述の様に、基板表面に於ける電極や配線材料の有無に拘わらず、半導体デバイス用基板の表面洗浄に好適に使用される。その中でも、本発明の洗浄液は、基板表面に於ける水の接触角が６０゜以上の疎水性を示す半導体デバイス用基板の洗浄に好適に使用される。
【００７７】
本発明の洗浄液の調製方法は、従来公知の方法によればよい。洗浄液の構成成分（例えば、界面活性剤、水酸化アンモニウム、水、必要に応じて錯化剤など、他の成分）のうち、何れか２成分または３成分以上を予め配合し、その後に残りの成分を混合してもよいし、一度に全部を混合してもよい。
【００７８】
前述の様に、本発明の半導体デバイス用基板洗浄液は、今後の新材料、つまり過酸化水素などの薬液に対して耐性の低い金属材料が表面にある半導体デバイス用基板でも、これら新材料を実質的に腐食しないので、前工程および後工程の何れにも使用可能な、優れた洗浄効果を奏する洗浄液となる。
【００７９】
すなわち、本発明の他の要旨は、以下の条件（ａ）、（ｂ）及び（ｃ）を満たすことを特徴とする、少なくとも半導体素子電極または金属配線を表面に有する、半導体デバイス用基板洗浄液に存する。
【００８０】
（ａ）実質的に半導体素子電極および金属配線を腐食しない。
（ｂ）汚染金属量が１０００〜５０００（×１０^１０ａｔｏｍｓ／ｃｍ^２）である基板を洗浄した場合に於いて、洗浄後の汚染金属量が１０（×１０^１０ａｔｏｍｓ／ｃｍ^２）以下である。
（ｃ）粒径０．１μｍ以上のパーティクルを８０００〜１０００００（個／０．０３ｍ^２）有する半径ｒの略円形状基板表面をｔ（分）間洗浄した場合に於いて、洗浄後、基板と中心を同じくする基板表面上の円周内でのパーティクル個数が、ｔ＝０．５〜１の際、円周半径０．６ｒの円周内で２００／ｔ個以下、または、円周半径０．９ｒの円周内では８００／ｔ個以下である。
【００８１】
なお、上記の（ｂ）及び（ｃ）の規定は、本発明の洗浄液の特性を規定したものであり、本発明の洗浄液が使用される洗浄条件を規定したものではない。また、本発明の洗浄液に於いて、「実質的に半導体素子電極及び金属配線を腐食しない」とは、洗浄する基板上の半導体素子電極や金属配線、具体的には、例えばＷやＣｕ等の電極材料や配線材料に対して、腐食や変質などの悪影響を生じさせず、これらの材料が、半導体デバイスとした際に、電極や配線などとして充分に機能することを意味する。
【００８２】
上記の本発明の洗浄液に於いて、条件（ｂ）及び（ｃ）を満たすということは、金属汚染、パーティクル汚染、何れの汚染をも充分に除去することが可能であることを示す。
【００８３】
条件（ｃ）は、洗浄対象が略円板状基板の表面、つまり略円形状基板表面の際、短時間の洗浄であっても、基板表面の位置によらず、基板表面を高度に清浄化出来ることを意味する。つまり粒径０．１μｍ以上のパーティクルを８０００〜１０００００（個／０．０３ｍ^２）有する半径ｒの略円形状基板表面を洗浄時間ｔ：０．５〜１［分］として洗浄した後、基板と中心を同じくする基板表面上の比較的内周部である円周半径０．６ｒの円周内では、残留するパーティクルを２００／ｔ個以下まで除去し、且つ、比較的外周部までをも含む円周半径０．９ｒの円周内に於いても、パーティクルを８００／ｔ個以下とし、基板表面を高度に清浄化できることを意味する。
【００８４】
また、上述した、本発明の半導体デバイス用基板洗浄液における、「洗浄した場合に於いて」とは、後述する様な洗浄方法によって、半導体デバイス用基板を洗浄液によって洗浄した場合であることを示す。洗浄方法は、通常、半導体デバイス用基板の洗浄時に採用されうる方法であれば特に限定されない。中でも、洗浄液の基板への接触方法は、基板上に洗浄液を流しながら基板を高速回転させるスピン式とし、洗浄液の液温度は室温〜９０℃の範囲とすることが安定した結果が得られるので好ましい。
【００８５】
更に、洗浄の際、物理力による洗浄方法、例えば洗浄ブラシを使用したスクラブ洗浄などの機械的洗浄や、基板に周波数０．５メガヘルツ以上の超音波を照射する超音波洗浄、そしてこれらを併用する洗浄方法などを採用することにより、より安定した洗浄結果が得られるので好ましい。
【００８６】
本発明の洗浄方法は、洗浄液を基板に直接接触させる方法で行われる。洗浄液の基板への接触方法には、洗浄槽に洗浄液を満たして基板を浸漬させるディップ式、ノズルから基板上に洗浄液を流しながら基板を高速回転させるスピン式、基板に液を噴霧して洗浄するスプレー式などが挙げられる。この様な洗浄を行うための装置としては、カセットに収容された複数枚の基板を同時に洗浄するバッチ式洗浄装置、１枚の基板をホルダーに装着して洗浄する枚葉式洗浄装置などがある。
【００８７】
洗浄時間は、バッチ式洗浄装置の場合、通常３０秒から３０分、好ましくは１〜１５分、枚葉式洗浄装置の場合、通常１秒から１５分、好ましくは５秒から５分である。洗浄時間が短すぎる場合は洗浄効果が十分でなく、長すぎる場合は、洗浄効果の向上は小さく、スループットの低下を招く。本発明の洗浄液は、上記の何れの方法にも適用できるが、短時間でより効率的な汚染除去が出来る点から、スピン式やスプレー式の洗浄に好ましく使用される。そしては、洗浄時間の短縮、洗浄液使用量の削減が問題となっている枚葉式洗浄装置に適用するならば、これらの問題が解消されるので好ましい。
【００８８】
洗浄液の温度は、通常は室温とされるが、洗浄効果を向上させる目的で、４０〜７０℃程度に加温することが好ましい。更に、表面にシリコンが露出している基板を洗浄する場合は、シリコン表面に有機物汚染が残留し易いため、基板を温度３００℃以上の加熱処理工程に供して熱分解させるか、または、オゾン水処理によって有機物を酸化分解処することが好ましい。
【００８９】
また、本発明の洗浄方法は、物理力による洗浄方法、例えば、洗浄ブラシを使用したスクラブ洗浄などの機械的洗浄や超音波洗浄と併用させることが好ましい。特に、超音波照射またはブラシスクラブを併用するならば、パーティクル汚染の除去性が更に向上し、洗浄時間の短縮にも繋がるので好ましい。特に、ＣＭＰ後の洗浄で樹脂製ブラシを使用して洗浄するのが好ましい。
【００９０】
樹脂製ブラシの材質は、任意に選択し得るが、例えばＰＶＡ（ポリビニルアルコール）を使用するのが好ましい。また、基板に周波数０．５メガヘルツ以上の超音波を照射するならば、界面活性剤との相乗作用により、パーティクルの除去性が著しく向上するので好ましい。更に、本発明の洗浄方法の前および／または後に、水の電気分解によって得られる電解イオン水、または、水に水素ガスを溶存させた水素水による洗浄を組み合わせてもよい。
【００９１】
【実施例】
次に、実施例により、本発明を具体的に説明するが、本発明はその要旨を超えない限り、以下の実施例により限定されるものではない。
【００９２】
実施例１、２及び比較例１〜３
（スクラブ式洗浄によるパーティクル汚染の洗浄性評価）
低誘電率膜（ＳｉＯＣ：炭素含有ＳｉＯ₂）付きの８インチシリコン基板（半径ｒが４インチの円板状基板）を、ＳｉＯ₂スラリー溶液に１０分間浸漬した。浸漬後の基板を超純水で１分間水洗し、マルチスピンナー（（株）カイジョー製「ＫＳＳＰ−２０１」）でスピン乾燥させた。その後、レーザー表面検査装置（日立電子エンジニアリング社製「ＬＳ−５０００」）により、基板表面に付着した微粒子数を測定し、０．２μｍ以上のＳｉＯ_２粒子が一定数量以上（ただし、上限は１０００００個）付着していることを確認した。
【００９３】
表１に示す洗浄液を使用し、上記のマルチスピンナーにより、ＰＶＡ製のブラシで上記のＳｉＯ_２粒子付着基板をブラシスクラブ洗浄し、パーティクルを除去した。洗浄液による洗浄は室温で１分間行なった。その後、超純水で基板を１分間洗浄した後、スピン乾燥し、洗浄済基板を得た。結果を表１に示す。
【００９４】
【表１】

【００９５】
実施例３〜６及び比較例４〜８
（スクラブ式洗浄によるパーティクル汚染の洗浄性評価）
先ず、実施例１と同様にＳｉＯ₂粒子付着基板を作成した。次いで、表２に示す洗浄液を使用し、洗浄時間を０．５分間とした以外は、実施例１と同様にＳｉＯ₂粒子付着基板を洗浄し、洗浄済基板を得た。結果を表２に示す。
【００９６】
表２中の濡れ性評価は次の方法で行った。すなわち、低誘電率膜（ＳｉＯＣ：炭素含有ＳｉＯ₂）付きのテスト片（２ｃｍ角）を表２に記載の各洗浄液に垂直に漬ける。０．５分後、テスト片を垂直に引き出し、テスト片の全面積に対する洗浄液が付いた面積の割合で評価した。評価基準は、○：８０％以上，△：５０％以上８０％未満，×：５０％未満とした。
【００９７】
【表２】

【００９８】
実施例７〜１０
（スクラブ式洗浄によるパーティクル汚染の洗浄性評価）
低誘電率膜（ＳｉＯＣ：炭素含有ＳｉＯ₂）付きの８インチシリコン基板（半径ｒが４インチの円板状基板）を、０．５重量％フッ酸で１分間表面処理した後、ＳｉＯ₂スラリー溶液に１０分間浸漬した。浸漬後の基板を超純水で１分間水洗し、マルチスピンナー（（株）カイジョー製「ＫＳＳＰ−２０１」）でスピン乾燥させた。その後、レーザー表面検査装置（日立電子エンジニアリング社製「ＬＳ−６６００」）で基板表面に付着した微粒子数を測定し、０．１１μｍ以上のＳｉＯ_２粒子が一定数量以上（ただし、上限は１０００００個）付着していることを確認した。
【００９９】
表３に示す洗浄液を使用し、前述のマルチスピンナーにより、ＰＶＡ製のブラシで上記のＳｉＯ₂粒子付着基板をブラシスクラブ洗浄し、パーティクルを除去した。洗浄液による洗浄は室温で０．５分間行なった。その後、超純水で基板を１分間洗浄した後、スピン乾燥して、洗浄済基板を得た。結果を表３に示す。
【０１００】
【表３】

【０１０１】
実施例１１、１２及び比較例９
（スクラブ式洗浄によるパーティクル汚染の洗浄性評価）
先ず、実施例１と同様にＳｉＯ₂粒子付着基板を作成した。次いで、表４に示す洗浄液を使用し、洗浄時間を０．５分間とした以外は、実施例１と同様にＳｉＯ₂粒子付着基板を洗浄し、洗浄済基板を得た。結果を表４に示す。
【０１０２】
【表４】

【０１０３】
実施例１３及び比較例１０
基板表面に厚さ約１００ｎｍの熱酸化膜の付いた４インチシリコン基板（半径ｒが２インチの円板状基板）を大気中に３時間暴露し、気中浮遊物を付着させた。基板表面検査装置（日立電子エンジニアリング社製「ＬＳ−５０００」）で測定した結果、基盤には粒径０．２μｍ以上のパーティクルが１万個以上（ただし、上限は１０００００個）付着していた。この基板を５０℃に温度制御された表３に記載の各洗浄液に各１０分間浸漬処理した後、１０分間純水による流水洗浄を行ない、スピンドライヤーにて乾燥した。洗浄処理後の基板上に残存するパーティクル数の測定結果を表５に示す。
【０１０４】
比較例１１
実施例１３に於いて、洗浄液として、２９重量％水酸化アンモニウム水溶液、５０重量％過酸化水素水、超純水を容量比１：４：２０にて混合して調製した溶液（ＡＰＭ洗浄液）を使用した以外は、実施例１３と同様に行なって評価した。結果を表５に示す。
【０１０５】
比較例１１の洗浄液は、洗浄後の付着粒子数が比較的少ないが、洗浄液に過酸化水素を含むために、今後の新材料への適用が出来ず、将来的には使用不可能となる。
【０１０６】
【表５】

【０１０７】
実施例１４及び比較例１２〜１４
自然酸化膜の付いた４インチシリコン基板（半径ｒが２インチの円板状基板）を０．５重量％ＨＦ水溶液に５分間浸漬処理して表面酸化膜を除去した基板を得た。これをSilicon（IV）Nitride粒子（Johnson Matthey社製「Stk#12145」）０．０２ｇ／Ｌが添加され且つ５０℃に温度制御された表４に記載の各洗浄液に１０分間浸漬処理し後、５分間純水による流水洗浄を行ない、スピンドライヤーにて乾燥した。基板表面検査装置（日立電子エンジニアリング社製「ＬＳ−５０００」）により、洗浄処理後の基板上に残存する粒径０．２μｍ以上のパーティクルの数を測定した。結果を表６に示す。
【０１０８】
【表６】

【０１０９】
実施例１５、比較例１５、１６
０．５重量％ＨＦ水溶液に５分間浸漬処理することにより表面自然酸化膜を除去した４インチシリコン基板（半径ｒが２インチの円板状基板）を用意した。これを各温度制御された表５に記載の洗浄液に所定時間浸漬処理した後、５分間純水による流水洗浄を行ない、スピンドライヤーにて乾燥した。基板乾燥後、直ちに原子間力顕微鏡（Digital Instruments社製Nano ScopeIIIa）で基板表面のＺ軸変位の標準偏差であるＲｍｓ（ｎｍ）を測定した。結果を表７に示す。
【０１１０】
上記の基板の表面荒れについて目視による評価を行ない。次の結果を得た。すなわち、比較例１５及び１６の場合は、基板表面に直径約１〜１０ｍｍ程度の無数のクレーター状凹凸と基板表面全体に亘る干渉縞の様な表面荒れが観察されたが、実施例１５の場合は観察されなかった。
【０１１１】
【表７】

【０１１２】
実施例１６〜１９及び比較例１７〜１９
０．５重量％ＨＦ水溶液に５分間浸漬処理することにより表面酸化膜を除去した膜厚約１００ｎｍの多結晶ポリシリコンのテスト片を用意した。このテスト片を５０℃に温度制御された表６に記載の各洗浄液に１０分間浸漬処理した後、５分間純水による流水洗浄を行ない、窒素ブローにて乾燥した。多結晶ポリシリコンの膜厚は、光干渉式膜厚測定器（ナノメトリクス社製「ナノスペックＬ−６１００」）で測定した。洗浄処理前後の膜厚測定よりエッチングレートを算出した。結果を表８に示す。
【０１１３】
【表８】

【０１１４】
実施例２０、参考例１
０．３重量％アンモニア水溶液に５分間浸漬処理することにより表面酸化膜を除去した膜厚約１００ｎｍのタングステンのテスト片を用意した。このテスト片を、４０℃に温度制御された表９に記載の各洗浄液に１０分間浸漬処理した後、５分間純水による流水洗浄を行ない、窒素ブローにて乾燥した。タングステンの膜厚は、全反射蛍光Ｘ線（Ｊｅｏｌ社製「ＲＩＸ−３０００」）を使用し、反射強度からの換算により導出した。洗浄処理前後の膜厚測定よりエッチングレートを算出した。結果を表９に示す。
【０１１５】
ここで、実施例２０と参考例１とを比較して明らかな通り、本発明の洗浄液は、単なるアルカリ水溶液に対して、基板表面のエッチングレートを抑制し、半導体デバイス用基板洗浄液として優れていることが分かる。
【０１１６】
比較例２０
実施例２０に於いて、洗浄液として、比較例１１と同様のＡＰＭ洗浄液を使用した以外は、実施例２０と同様に行なって評価した。結果を表９に示す。
【０１１７】
【表９】

【０１１８】
実施例２１、比較例２１
４インチシリコン基板（半径ｒが２インチの円板状基板）を、金属イオン（Ｆｅ、Ｃｕ）を含有したＡＰＭ洗浄液に浸漬した。このＡＰＭ洗浄液は、２９重量％アンモニア水、３１重量％過酸化水素水および水を容量比１：１：５で混合し、これに金属含有量がＦｅ（２０ｐｐｂ）、Ｃｕ（１ｐｐｍ）となる様に金属イオン含有水溶液を添加して調製した。浸漬後のシリコン基板を超純水で１０分間水洗し、窒素ブローにより乾燥し、金属で汚染されたシリコン基板を得た。
【０１１９】
このシリコン基板上の汚染金属（Ｆｅ、Ｃｕ）の分析は、汚染されたシリコン基板および洗浄後のシリコン基板共に、次の方法で行なった。すなわち、基板表面にある金属を、フッ酸０．１重量％と過酸化水素１重量％を含む水溶液で基板を処理することによって回収し、誘導結合プラズマ質量分析計（ＩＣＰ−ＭＳ）で金属量を測定し、基板表面での金属濃度（ａｔｏｍｓ／ｃｍ^２）に換算する。
【０１２０】
金属で汚染された上記のシリコン基板の洗浄を、表１０に示す洗浄液を使用し、洗浄液温度６０℃、洗浄時間１０分とし、ディップ式洗浄法により行った。汚染されたシリコン基板の分析結果および洗浄済シリコン基板表面の残留金属（Ｆｅ，Ｃｕ）を表１０に示す。
【０１２１】
【表１０】

【０１２２】
以上の結果から、本発明の洗浄液は、疎水性である低誘電率膜に付着した微粒子（パーティクル）の除去性に優れていることが明らかである。また、水酸化アンモニウム溶液やＡＰＭ溶液による従来の洗浄方法に比し、気中浮遊物由来のパーティクル付着物に対しても、より優れた除去性を有していることが判る。
【０１２３】
同様に、系内に微粒子（パーティクル）等が混入しても、本発明の洗浄方法で除去することにより、基板への付着を抑制することが可能となる。更に、従来の洗浄方法と比較し、アルカリ性の洗浄液に於いてもシリコン表面のラフネス（表面あれ）を極めて小さく抑制することが可能であり、ポリシリコンやタングステンへのエッチングによる加工寸法変化などの副作用が殆ど無く、洗浄性とラフネス抑制および低エッチング性を両立することが可能となる。
【０１２４】
そして、本発明の洗浄液は、過酸化水素などの薬液に対して耐性の低い材料が表面にある半導体デバイス用基板であっても、前工程および後工程の何れにも使用可能な、優れた洗浄効果を奏する洗浄液であることが明白である。
【０１２５】
【発明の効果】
本発明の洗浄液によれば、シリコン等の半導体材料、窒化シリコン、酸化シリコン、ガラス、低誘電率材料などの絶縁材料、遷移金属または遷移金属化合物などを表面の一部あるいは全面に有する半導体デバイス用基板に於いて、基板表面に付着した微粒子（パーティクル）、有機汚染、金属汚染を洗浄により効果的に除去し、系内に微粒子などが混入した際にも付着抑制が可能である。特に、薬液をはじき易い疎水性の低誘電率材料の濡れ性を良くし、洗浄性に優れている。また、アルカリ性洗浄液に於いても、洗浄性に加え、シリコン表面のラフネス抑制および低エッチング性を両立することが可能であり、半導体デバイス、ディスプレイデバイス等の製造工程における汚染洗浄用などの表面処理方法として、工業的に非常に有用である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cleaning solution and a cleaning method for a substrate for a semiconductor device, and is used for cleaning a substrate surface of a semiconductor, glass, metal, ceramics, resin, magnetic material, superconductor, etc. in which metal contamination or particle contamination is a problem. It relates to a cleaning solution. Specifically, the present invention relates to a cleaning liquid and a cleaning method for cleaning a semiconductor device substrate surface in a process of manufacturing a semiconductor device substrate for a semiconductor element or a display device, which requires a highly clean substrate surface. .
[0002]
The cleaning liquid and the cleaning method of the present invention have a surface of a semiconductor material such as silicon, an insulating material such as silicon nitride, silicon oxide, glass, a low dielectric constant (Low-k) material, a transition metal or a transition metal compound, in particular. In the semiconductor device substrate on the entire surface or the entire surface, remove silica particles, alumina particles, fine particles (particles) such as organic particles, organic contaminants such as resist residues, and metal contamination on the substrate surface. Re-adhesion can be suppressed, and the substrate surface can be highly purified without causing roughness or corrosion of the substrate surface.
[0003]
[Prior art]
In the manufacturing process of semiconductor devices such as flat panel displays such as TFT liquid crystal, microprocessors, memories, and CCDs, silicon, silicon oxide (SiO2)₂), Pattern formation and thin film formation are performed on the surface of a substrate such as glass with a size of submicron to quarter micron. Therefore, in each of these manufacturing steps, it is an extremely important issue to remove even slight contamination of the substrate surface and to highly clean the substrate surface. Among contaminations, in particular, particle contamination and metal contamination, which are minute contaminations, are difficult to remove. However, since the electrical characteristics and yield of the semiconductor device are reduced due to such contamination, it is necessary to remove such contamination as much as possible before bringing it into the next process. In order to remove such contamination, the substrate surface is generally cleaned with a cleaning liquid.
[0004]
In recent years, there has been a demand for further improvement in throughput and production efficiency in the manufacture of semiconductor devices. And for semiconductor device manufacturing substrates that are becoming increasingly miniaturized and highly integrated, they have excellent removability prevention after removal as well as particle surface contamination and metal contamination on the substrate surface, and quickly. A cleaning liquid and a cleaning method capable of highly cleaning the surface are desired.
[0005]
Generally, it is known that an alkaline aqueous solution is effective as a cleaning liquid used for removing particle contamination. An alkaline aqueous solution such as an aqueous ammonia solution, an aqueous potassium hydroxide solution, or an aqueous tetramethylammonium hydroxide solution is used for cleaning the substrate surface for a semiconductor device. In addition, cleaning (referred to as “SC-1 cleaning” or “APM cleaning”) by a cleaning liquid (referred to as “SC-1 cleaning liquid” or “APM cleaning liquid”) containing ammonia, hydrogen peroxide, and water is also widely used. (For example, refer nonpatent literature 1).
[0006]
And recently, in order to improve the performance of such alkaline cleaning liquid, specifically, the etching of the surface of the substrate for semiconductor devices is suppressed, the surface roughness is suppressed and the wettability of the substrate surface is improved, and Various proposals have been made to add various surfactants to an alkaline cleaning solution for the purpose of improving the removability of particle contamination.
[0007]
For example, in order to suppress the roughening of the substrate surface due to the cleaning liquid, it has been proposed to add a surfactant to an alkaline hydrogen peroxide aqueous solution so that the contact angle of the cleaning liquid with respect to the substrate surface is 10 degrees or less (for example, Patent Documents). 1). Further, in order to improve the wettability of the cleaning liquid to the substrate surface, a hydrogen peroxide-containing alkaline cleaning liquid to which an ethylene oxide addition type nonionic surfactant having an addition mole number of ethylene oxide of 3 to 10 is added has been proposed. (For example, refer to Patent Document 2).
[0008]
In addition, in order to suppress the etching of the surface of a silicon substrate, which is a typical semiconductor device substrate, it has been proposed to add various surfactants to an alkaline cleaning solution (see, for example, Patent Document 3). In particular, in order to improve the performance of removing organic contaminants, a cleaning liquid used for cleaning a semiconductor device substrate containing a specific surfactant has been proposed (see, for example, Patent Document 4). In order to improve decontamination, it has also been proposed to add alkylbenzene sulfonic acid to an alkaline cleaning liquid containing hydrogen peroxide (see, for example, Patent Document 5). In order to improve particle removability, it has also been proposed to add a fluorine-based surfactant made of a fluoroalkylsulfonamide compound to the APM cleaning liquid (see, for example, Patent Document 6).
[0009]
Further, in the cleaning of the semiconductor device substrate, an acidic cleaning solution is also useful in addition to the above alkaline cleaning solution. In general, acidic cleaning solutions are effective for removing metal contamination on the substrate surface, but they are not suitable for removing particle contamination. For the purpose of improving particle contamination, various cleaning agents are also used in acidic cleaning solutions. It has been proposed to add. For example, it has been proposed to clean a silicon wafer using a specific surfactant and hydrofluoric acid (see, for example, Patent Document 7).
[0010]
In addition, it has been proposed to add a surfactant and ozone to a hydrofluoric acid aqueous solution used for cleaning a silicon wafer (see, for example, Patent Document 8). It has also been proposed to add an organic acid compound to a dispersant and / or a surfactant in order to remove metal impurities adsorbed on a substrate having metal wiring on the surface and particle contamination (see, for example, Patent Document 9).
[0011]
In recent years, with the miniaturization and high stacking of semiconductor devices, wiring (hereinafter simply referred to as “wiring”) and electrodes in semiconductor elements (hereinafter simply referred to as “electrodes”) connecting minute semiconductor elements in semiconductor devices. As a metal material used for "", new metal materials such as copper (Cu) and tungsten (W) are being introduced. Specifically, for example, Cu having a resistance value lower than that of conventionally used aluminum (Al) is being adopted as a wiring material.
[0012]
Another novel material is an interlayer insulating film between semiconductor elements having a stacked structure. As this interlayer insulating film, conventionally used SiO 2₂A low dielectric constant film using a film made of an organic polymer material or an inorganic polymer material having a lower dielectric constant than the film is being adopted. This interlayer insulating film is exposed on the substrate together with the wiring during a substrate cleaning process (hereinafter, also referred to as a “post process”) performed after the metal wiring is formed on the surface during the manufacturing process of the semiconductor device. is doing.
[0013]
Further, tungsten is being introduced into the electrode as an electrode material having a low resistance value and advantageous for fine processing. The electrode is usually exposed on the surface of the substrate during the substrate cleaning step before metal wiring formation (hereinafter also referred to as “pre-process”). Conventionally, since the substrate surface to be cleaned in the previous process is entirely composed of a Si compound, even a slight contamination affects the semiconductor device, so that the substrate surface has to be highly cleaned. Therefore, powerful cleaning by RCA cleaning is essential.
[0014]
In recent years, attempts have been made to adapt the various proposals described above in order to highly clean even a substrate on which a new material as described above is exposed.
[0015]
[Non-Patent Document 1]
W. Kern and D.A. Puotinen: RCA Review, p.187, June (1970)
[Patent Document 1]
JP-A-5-335294
[Patent Document 2]
Japanese Patent No. 3169024
[Patent Document 3]
Japanese Patent Laid-Open No. 2001-40389
[Patent Document 4]
JP-A-11-112418
[Patent Document 5]
JP 7-245281 A
[Patent Document 6]
JP-A-5-251416
[Patent Document 7]
JP 7-216392 A
[Patent Document 8]
JP-A-8-69990
[Patent Document 9]
JP 2001-7071 A
[0016]
[Problems to be solved by the invention]
In the conventional post-process using Al wiring, the Al wiring is weak against strong acids and strong alkalis, and is less affected by metal contamination than the previous process, so only simple cleaning with ultrapure water or organic solvent is performed. It was broken. However, when Cu was used instead of Al, the following two problems were newly generated.
[0017]
First, Cu is one of the most disliked contaminants for Si, and is an oxide film (SiO2) on the surface of a semiconductor device.₂The diffusion rate of Cu in the film) is fast, and the adverse effect is much higher than that of Al.
[0018]
Second, unlike Al, Cu is problematic in that it cannot be dry etched. In order to form a wiring made of Cu, a wiring is formed by performing Cu plating on an insulating film dug in advance (for forming a Cu wiring), and then an unnecessary portion is formed by a method such as CMP (Chemical Mechanical Polishing). Therefore, it is unavoidable to form a wiring by a so-called damascene method.
[0019]
In wiring formation by the damascene method, a large amount of Cu and abrasive particles (particles represented by aluminum oxide particles) in the slurry used for CMP may contaminate the Cu wiring and the surface of the low dielectric constant film. It becomes a problem. Such contamination of the substrate surface can no longer be removed by simple cleaning with ultrapure water or an organic solvent, which has been a serious problem.
[0020]
When conventional RCA cleaning with strong acid or strong alkali is performed against the contamination as described above, a new problem arises that new metal materials such as Cu and W are dissolved in hydrogen peroxide. Furthermore, since the surface of the low dielectric constant film is hydrophobic, the wettability of the cleaning liquid is poor, and the cleaning liquid is repelled. In particular, there is a problem that it is difficult to sufficiently remove particle contamination.
[0021]
Therefore, in the process of cleaning a substrate having a new material as described above, serious problems have arisen in the future, such as it becomes impossible to perform cleaning using an RCA cleaning solution containing hydrogen peroxide. In cleaning a substrate having a new metal material weak against chemicals such as hydrogen oxide on the surface, development of a new cleaning liquid is strongly desired.
[0022]
On the other hand, as described above, a cleaning liquid containing a surfactant has been developed. However, there has been no cleaning solution that can sufficiently prevent re-adhesion along with the removal of metal contamination and particle contamination and satisfy the problems described in (1) to (3) below. It was an issue to be solved.
[0023]
(1) At room temperature or at the time of heating, the surfactant does not precipitate as oil droplets in the cleaning liquid and does not become cloudy, so that the cleaning performance is not deteriorated or the oil droplets remain on the substrate surface.
(2) The foaming property is small and does not adversely affect the operation of the cleaning device.
(3) The surfactant is a substance that does not adversely affect the natural environment, and the cleaning waste liquid can be appropriately treated.
[0024]
For example, since an anionic surfactant generally has no cloud point, it can be used at a high temperature (for example, 80 ° C. or higher) in expectation of a high cleaning effect. However, since it is highly foamable, the operability of the cleaning device may be adversely affected.
[0025]
Nonionic surfactants have high cleaning performance and low foaming properties, but generally have a low cloud point. Therefore, if a cleaning effect is expected with a high cleaning effect, the surfactant appears as oil droplets in the cleaning solution and remains on the substrate.
[0026]
[Means for Solving the Problems]
In order to solve the above-described problems, the present inventors diligently studied a substrate cleaning solution for a semiconductor device using a surfactant. In particular, attention was focused on surfactants used in cleaning liquids, especially ethylene oxide surfactants that are nonionic surfactants.
[0027]
The ethylene oxide type surfactant has a hydrocarbon group and a polyoxyethylene group in the same molecular structure. In the ethylene oxide type surfactant having such a structure, the inventors of the present invention have a ratio between the number of carbon atoms (m) contained in the hydrocarbon group and the number of oxyethylene groups in the polyoxyethylene group (n). We focused on surfactants in a specific range where (m / n) is 1 to 1.5, carbon number (m) is 9 or more, and the number of oxyethylene groups (n) in the polyoxyethylene group is 7 or more. .
[0028]
Many of the ethylene oxide surfactants within this specific range are solid and have low solubility in water at room temperature and atmospheric pressure. Therefore, such an ethylene oxide type surfactant has a low handleability in an industrial production process and has been avoided. However, a substrate cleaning solution for a semiconductor device containing an alkali or organic acid prepared by heating and melting an ethylene oxide surfactant within a specific range and dissolving in water is surprisingly substantially Even without hydrogen peroxide, good cleaning performance was exhibited. In particular, it was excellent in cleanability against fine particle contamination (particle removal property with a particle size of the order of 0.1 μm), which cannot be predicted from a general contamination cleaning effect. In addition, the substrate cleaning solution for semiconductor devices described above has an excellent cleaning effect because of its hydrophobicity, which easily repels the aqueous cleaning solution and exhibits sufficient wettability even on the surface of a low dielectric constant film having low particle removability. The present inventors have found these things and have completed the present invention.
[0029]
  That is, the gist of the present invention is as follows.After chemical mechanical polishing a substrate for a semiconductor device having silicon, a transition metal or a transition metal compound on the surface,Contains at least the following components (A), (B) and (C)And cleaning the substrate for a semiconductor device using a cleaning solution having a hydrogen peroxide content of 10 ppm or less.Exist.
[0030]
  Component (A): Polyoxyethylene alkyl ether represented by the following general formula (II)
[Chemical 3]

(However, R²Represents a hydroxyl group, an amino group, an alkoxy group, or an alkyl group which may be substituted with a halogen, the number of carbons (m) contained in the alkyl group is 9 or more, and (n) represents a number of 7 or more. .And the ratio (m / n) of carbon number (m) in an alkyl group and oxyethylene group number (n) in a polyoxyethylene group is 1-1.5.)
  Ingredient (B): Water
  Component (C): Alkali
[0031]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail. The cleaning liquid of the present invention contains at least a specific surfactant as the component (A), water as the component (B), and an alkali or organic acid as the component (C).
[0032]
In the present invention, the surfactant used as component (A) has a hydrocarbon group which may have a substituent (excluding a phenyl group) and a polyoxyethylene group, and the hydrocarbon group contains The ratio (m / n) of the number of carbons (m) and the number of oxyethylene groups (n) in the polyoxyethylene group is 1 to 1.5, the number of carbons (m) is 9 or more, and the number of oxyethylene groups (n) Is an ethylene oxide type surfactant having 7 or more.
[0033]
When the ratio (m / n) is less than 1, the particle removing ability in the liquid and the corrosion inhibition of silicon are insufficient. In addition, the solubility in water decreases due to the increase in oxyethylene chain length, and the load of waste liquid treatment also increases. On the other hand, when the ratio exceeds 1.5, an O / W type emulsion is formed during washing in an alkaline solution, and the surfactant precipitates as fine oil droplets and becomes cloudy. Causes problems such as droplet residue. The ratio (m / n) is preferably 1 to 1.4.
[0034]
When the above carbon number (m) is less than 9, even if the (m / n) ratio is within the optimum range, the particle removability is lowered. On the other hand, when (m) is too large, the solubility in water and the load of waste liquid treatment increase, which is not preferable. Therefore, carbon number (m) becomes like this. Preferably it is 9-16, More preferably, it is 10-14. However, when the hydrocarbon group constituting the component (A) has a hydrocarbon group as a substituent, the total number of carbon atoms in the hydrocarbon group as the main chain and the hydrocarbon group as the substituent is m. And
[0035]
Moreover, when said (n) is less than 7, even if (m / n) ratio is in the said optimal range, particle removability will fall. When (n) is too large, the load of the waste liquid treatment is increased, and the surfactant is easily decomposed in the cleaning liquid. Therefore, (n) is preferably 7 to 16, more preferably 7 to 14.
[0036]
By using the above-mentioned ethylene oxide type surfactant defined in the present invention, both the wettability of the cleaning liquid and the removability of particles are improved. Examples of the ethylene oxide type surfactant include polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, polyoxyethylene alkylamine, polyoxyethylene alkyl ether sulfate, and the like. In particular, polyoxyethylene alkyl ethers represented by the following general formula (II) are preferable from the viewpoints of particle contamination removability and anti-reattachment ability.
[0037]
[Formula 4]

(However, R²Represents a hydroxyl group, an amino group, an alkoxy group, or an alkyl group which may be substituted with a halogen, the number of carbons (m) contained in the alkyl group is 9 or more, and (n) represents a number of 7 or more. . )
[0038]
Specific examples of the polyoxyethylene alkyl ether include polyoxyethylene (n = 8) nonyl ether, polyoxyethylene (n = 9) decyl ether, polyoxyethylene (n = 11) undecyl ether, polyoxyethylene. (N = 10) lauryl ether, polyoxyethylene (n = 11) lauryl ether, polyoxyethylene (n = 10) tridecyl ether, polyoxyethylene (n = 12) tridecyl ether, polyoxyethylene (n = 11 ) Tetradecyl ether, polyoxyethylene (n = 13) tetradecyl ether, polyoxyethylene (n = 12) pentadecyl ether, polyoxyethylene (n = 14) pentadecyl ether, polyoxyethylene (n = 12) cetyl Ether, polyoxyethylene ( = 15) cetyl ether, polyoxyethylene (n = 18) oleyl ether, and the like. In addition, the numerical value in said n represents n in the said general formula (II).
[0039]
In the present invention, within the scope of the present invention, a plurality of ethylene oxide surfactants different in (m) and (n) may be used in an arbitrary ratio. Furthermore, when using multiple types of surfactant together, the average value of (m / n) of all the surfactants is 1 to 1.5, the average value of (m) is 9 or more, and the average value of (n) is 7 If the above conditions are satisfied, in each individual surfactant, (m / n) is less than 1.0 or more than 1.5, (m) is less than 9, and (n) is 7 It may be less.
[0040]
The content of the component (A) in the cleaning liquid is usually 0.0001 to 1% by weight, preferably 0.0003 to 0.5% by weight, more preferably 0.001 to 0.1% by weight, and particularly preferably 0. 0.001 to 0.05% by weight. When the concentration of the component (A) is too low, the particle contamination removal performance is not sufficient. On the other hand, when the concentration of the component (A) is too high, there is no change in the particle contamination removal performance, and foaming becomes remarkable and cleaning is performed. It may be unsuitable for the process, and the load in the case of biodegrading the waste liquid may increase.
[0041]
The component (A) may contain metal impurities such as Na, K, and Fe of about 1 to several thousand ppm in the form that is usually sold. In such a case, the component (A) becomes a metal contamination source. Therefore, it is preferable to purify and use the surfactant used as component (A). The content of each metal impurity is usually 10 ppm or less, preferably 1 ppm or less, more preferably 0.1 ppm or less. As a purification method, for example, a method in which a surfactant is dissolved in water, then passed through an ion exchange resin, and a metal impurity is captured by the resin is suitable.
[0042]
By using the component (A) purified as described above, it is possible to obtain a cleaning liquid in which the metal impurity content is extremely reduced. As the cleaning liquid of the present invention, among the metal impurities in the cleaning liquid, the content of at least Na, Mg, Al, K, Ca, Fe, Cu, Pb, and Zn is 20 ppb or less, particularly 5 ppb or less, particularly 0 .1 ppb or less is preferable.
[0043]
In the present invention, a surfactant other than the component (A) may be used as long as the effects of the present invention are not impaired. As the surfactant other than the component (A), any of a cationic surfactant, an anionic surfactant and a nonionic surfactant may be used. Among them, it is preferable to use an anionic surfactant or a nonionic surfactant. Specifically, for example, as an anionic surfactant, an alkylbenzene sulfonic acid having 8 to 12 carbon atoms and its surfactant are used. Examples thereof include salts, alkyl methyl tauric acids having 8 to 12 carbon atoms and salts thereof, and alkyl sulfates having 8 to 12 carbon atoms and salts thereof. Examples of nonionic surfactants include surfactants composed only of polyoxyalkylene.
[0044]
In the present invention, water is used as component (B). When it is desired to obtain a highly clean substrate surface, deionized water, preferably ultrapure water is usually used. Further, electrolytic ion water obtained by electrolysis of water, hydrogen water in which hydrogen gas is dissolved in water, or the like can also be used.
[0045]
In the present invention, alkali or organic acid is used as component (C). That is, the cleaning liquid of the present invention is an alkaline cleaning liquid or an acidic cleaning liquid.
[0046]
Although the kind of alkali used by this invention is not specifically limited, Ammonium hydroxide (ammonia aqueous solution) and an organic alkali are mentioned as a typical alkali. Examples of the organic alkali include amines such as quaternary ammonium hydroxide, amine and amino alcohol. As the quaternary ammonium hydroxide, those having a hydroxyl group, an alkoxy group, an alkyl group having 1 to 4 carbon atoms which may be substituted with a halogen, or a hydroxyalkyl group having 1 to 4 carbon atoms are preferable. All groups may be the same or different.
[0047]
Examples of the alkyl group as described above include lower alkyl groups having 1 to 4 carbon atoms such as a methyl group, an ethyl group, a propyl group, and a butyl group, and examples of the hydroxyalkyl group include a hydroxymethyl group, a hydroxyethyl group, a hydroxy group. C1-C4 lower hydroxyalkyl groups, such as a propyl group and a hydroxybutyl group, are mentioned.
[0048]
Specific examples of the quaternary ammonium hydroxide having the above substituent include tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, trimethyl (hydroxyethyl) ammonium hydroxide (common name: choline), triethyl (hydroxy). And ethyl) ammonium hydroxide. On the other hand, examples of amines include ethylenediamine, monoethanolamine, and trimethanolamine.
[0049]
Among the alkalis described above, ammonium hydroxide, tetramethylammonium hydroxide (TMAH), trimethyl (hydroxyethyl) ammonium hydroxide (for reasons such as cleaning effect, low metal residue, economy, and stability of the cleaning solution ( Common name: choline) is preferred. These alkalis may be used independently and may use 2 or more types in arbitrary ratios.
[0050]
The concentration of the alkali in the cleaning liquid may be selected as appropriate, but is preferably a concentration at which the pH of the cleaning liquid is 9 or higher. If the alkali concentration is too low and the pH is not high, the decontamination effect that is the object of the present invention may not be obtained. On the other hand, if the pH is too high, the effect of increasing the pH cannot be obtained, which is economically disadvantageous, and the risk of damage to the substrate surface due to etching increases. Accordingly, the pH of the alkaline cleaning liquid is preferably 9 to 13, more preferably 10 to 12.5, and particularly preferably 10.5 to 12.
[0051]
Although the kind of organic acid used by this invention is not specifically limited, Organic carboxylic acid or organic sulfonic acid is preferable. Typical organic carboxylic acids include formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, ethylmethylacetic acid, trimethylacetic acid, succinic acid, succinic acid, malonic acid, citric acid, tartaric acid, malic acid, etc. Can be mentioned. Among these, one or more selected from the group of acetic acid, propionic acid, succinic acid, succinic acid, malonic acid, citric acid, tartaric acid and malic acid are preferable, and selected from the group of acetic acid, succinic acid and citric acid. One or two or more of these are more preferred. Acetic acid is most preferably used because it is used as an etchant material for a semiconductor substrate, and can be obtained at a low cost by a distillation operation with high purity and low metal impurities, and no generation of powder due to water evaporation occurs.
[0052]
Typical examples of the organic sulfonic acid include methanesulfonic acid, ethanesulfonic acid, n-propanesulfonic acid, i-propanesulfonic acid, n-butanesulfonic acid, and phenylsulfonic acid. Among these, methanesulfonic acid and / or ethanesulfonic acid are preferable, and methanesulfonic acid is particularly preferable. Said organic acid may be used independently and may use 2 or more types in arbitrary ratios.
[0053]
The concentration of the organic acid in the cleaning solution may be appropriately selected, but is preferably a concentration at which the pH of the acidic cleaning solution is 1 to 5. If the concentration of the organic acid is too low and the pH is not sufficiently low, the effects of removing contamination and preventing adhesion, which are the objects of the present invention, may not be obtained. On the other hand, if the concentration is too high, the effect of lowering the pH is not obtained, which is not only economically disadvantageous, but also can cause corrosion of the substrate surface, which is not preferable. The pH of the acidic cleaning solution is preferably 2 to 3.
[0054]
In the cleaning liquid of the present invention, the inclusion of a complexing agent is preferable because a very highly cleaned surface with further reduced metal contamination on the substrate surface can be obtained. Any conventionally known complexing agent can be used. The type of complexing agent may be selected based on comprehensive judgment from the contamination level of the substrate surface, the type of metal, the level of cleanliness required for the substrate surface, the cost of the complexing agent, chemical stability, etc. The following (1) to (4) are exemplified.
[0055]
(1) Compounds having nitrogen as a donor atom and a carboxyl group and / or a phosphonic acid group:
For example, amino acids such as glycine; iminodiacetic acid, nitrilotriacetic acid, ethylenediaminetetraacetic acid [EDTA], trans-1,2-diaminocyclohexanetetraacetic acid [CyDTA], diethylenetriaminepentaacetic acid [DTPA], triethylenetetramine 6 acetic acid [ Nitrogen-containing carboxylic acids such as TTHA]; nitrogen-containing phosphonic acids such as ethylenediaminetetrakis (methylenephosphonic acid) [EDTPO], nitrilotris (methylenephosphonic acid) [NTPO], propylenediaminetetra (methylenephosphonic acid) [PDTMP], etc. Can be mentioned.
[0056]
(2) OH group and / or O having an aromatic hydrocarbon ring and directly bonded to a carbon atom constituting the aromatic hydrocarbon ring^-Compound having two or more groups:
Examples thereof include phenols such as catechol, resorcinol, and tyrone, and derivatives thereof.
[0057]
(3) Compound having both the structures of (1) and (2) above:
[0058]
(3-1) Ethylenediaminedioltohydroxyphenylacetic acid [EDDHA] and its derivatives:
For example, ethylenediaminedioltohydroxyphenylacetic acid [EDDHA], ethylenediamine-N, N′-bis [(2-hydroxy-5-methylphenyl) acetic acid] [EDDHMA], ethylenediamine-N, N′-bis [(2-hydroxy Aromatic nitrogen-containing carboxylic acids such as -5-chlorophenyl) acetic acid] [EDDHCA], ethylenediamine-N, N'-bis [(2-hydroxy-5-sulfophenyl) acetic acid] [EDDHSA]; ethylenediamine-N, N Aromatic nitrogen-containing phosphonic acids such as' -bis [(2-hydroxy-5-methylphenyl) phosphonic acid], ethylenediamine-N, N'-bis [(2-hydroxy-5-phosphophenyl) phosphonic acid] It is done.
[0059]
(3-2) N, N'-bis (2-hydroxybenzyl) ethylenediamine-N, N'-2acetic acid [HBED] and its derivatives:
For example, N, N′-bis (2-hydroxybenzyl) ethylenediamine-N, N′-2acetic acid [HBED], N, N′-bis (2-hydroxy-5-methylbenzyl) ethylenediamine-N, N′— Examples include diacetic acid [HMBED], N, N′-bis (2-hydroxy-5-chlorobenzyl) ethylenediamine-N, N′-2 acetic acid, and the like.
[0060]
(4) Other:
For example, amines such as ethylenediamine, 8-quinolinol and o-phenanthroline; carboxylic acids such as formic acid, acetic acid, oxalic acid and tartaric acid; hydrogen halides such as hydrofluoric acid, hydrochloric acid, hydrogen bromide and hydrogen iodide; Salts of oxo acids such as phosphoric acid and condensed phosphoric acid, and salts thereof.
[0061]
The complexing agent may be in the form of an acid, or may be in the form of a salt such as an ammonium salt.
[0062]
Among the complexing agents described above, nitrogen-containing carboxylic acids such as ethylenediaminetetraacetic acid [EDTA] and diethylenetriaminepentaacetic acid [DTPA]; ethylenediaminetetrakis (methylenephosphonic acid) [EDTPO] for reasons such as cleaning effect and chemical stability. , Nitrogen-containing phosphonic acids such as propylenediaminetetra (methylenephosphonic acid) [PDTMP]; ethylenediaminedioltohydroxyphenylacetic acid [EDDDHA] and its derivatives; N, N′-bis (2-hydroxybenzyl) ethylenediamine-N, N ′ -2 Acetic acid [HBED] is preferred.
[0063]
Among them, from the viewpoint of the cleaning effect, enediaminediolhydroxyhydroxyacetic acid [EDDHA], ethylenediamine-N, N′-bis [(2-hydroxy-5-methylphenyl) acetic acid] [EDDHMA], diethylenetriaminepentaacetic acid [DTPA], ethylenediamine Tetraacetic acid [EDTA] and propylenediaminetetra (methylenephosphonic acid) [PDTMP] are preferred. Said complexing agent may be used independently and may use 2 or more types in arbitrary ratios.
[0064]
The concentration of the complexing agent in the cleaning liquid may be arbitrarily selected according to the type and amount of contaminating metal impurities and the cleanliness level required for the substrate surface, but is usually 1 to 10,000 ppm, preferably 5 to 1000 ppm, more preferably 10 to 200 ppm. If the concentration of the complexing agent is too low, the effect of decontamination and adhesion prevention by the complexing agent cannot be obtained, and if it is too high, the effect corresponding to the increase in concentration cannot be obtained, which is economically disadvantageous, The complexing agent adheres to the substrate surface, increasing the risk of remaining after the surface treatment.
[0065]
In addition, since the complexing agent contains about 1 to several thousand ppm of metal impurities such as FeAl and Zn in reagents that are usually sold, the complexing agent used in the present invention is a source of metal contamination. There are cases. These metals exist in the form of a stable complex with the complexing agent in the initial stage, but when the complexing agent decomposes during a long period of use as a surface cleaning solution, it is liberated and the substrate Adhere to the surface. Therefore, the complexing agent used in the present invention is preferably purified before use. The content of each metal impurity contained is usually 5 ppm or less, preferably 1 ppm or less, more preferably 0.1 ppm or less. As a purification method, for example, a method in which a complexing agent is dissolved in an acidic or alkaline solution, insoluble impurities are removed by filtration, neutralized again to precipitate crystals, and the crystals are separated from the liquid is preferable. is there.
[0066]
In addition, the cleaning liquid of the present invention may contain other components in an arbitrary ratio as long as the performance is not impaired. Other components include sulfur-containing organic compounds (2-mercaptothiazoline, 2-mercaptoimidazoline, 2-mercaptoethanol, thioglycerol, etc.), nitrogen-containing organic compounds (benzotriazole, alkylbenzotriazole, tetrasol, 3-aminotriazole) , N (R)₃(R is an alkyl group having 1 to 4 carbon atoms), N (ROH)₃(R is an alkyl group having 1 to 4 carbon atoms), urea, thiourea, etc.), water-soluble polymers (polyethylene glycol, polyvinyl alcohol, etc.), alkyl alcohol compounds (ROH (R is an alkyl group having 1 to 4 carbon atoms)) Anti-corrosive agents such as sulfuric acid, hydrochloric acid, etc., reducing agents such as hydrazine, dissolved gases such as hydrogen, argon, nitrogen, etc., removal effect of polymers attached firmly after dry etching such as hydrofluoric acid, ammonium fluoride, BHF Etching accelerators that can be expected to be used.
[0067]
  And as other components to be included in the cleaning liquid of the present inventionAndExamples of the oxidizing agent include ozone and oxygen. When cleaning the surface of a silicon (bare silicon) substrate without an oxide film in the step of cleaning a semiconductor device substrate, it is preferable because the surface roughness due to etching on the substrate surface can be suppressed by adding an oxidizing agent..
[0068]
By the way, the wiring of a semiconductor device and device element electrodes made of a metal material that reacts and dissolves with hydrogen peroxide may be exposed on the surface of the substrate to be cleaned. Examples of such a metal material include transition metals or transition metal compounds such as Cu and W. At this time, it is preferable that the cleaning liquid used for cleaning does not substantially contain hydrogen peroxide. Unlike the conventional APM cleaning liquid, the cleaning liquid of the present invention exhibits sufficient cleaning performance without adversely affecting such a metal material even if it does not substantially contain hydrogen peroxide.
[0069]
  In the cleaning liquid of the present invention, “substantially does not contain hydrogen peroxide” means that the material on the substrate to be cleaned, for example, wiring materials such as Cu and W, electrode materials, and low dielectric constant films are used. This means that it does not cause adverse effects such as corrosion or alteration by hydrogen peroxide. That is, when these materials are used as semiconductor devices, it means that they function sufficiently as wirings or electrodes. For that purpose, it is preferable that hydrogen peroxide is not contained in the cleaning liquid of the present invention, and even if it is contained, the content thereof is suppressed to a low level. Its content is1It is 0 ppm or less, preferably 1 ppm, more preferably 10 ppb or less.
[0070]
The cleaning liquid of the present invention is used for cleaning substrate surfaces of semiconductors, glass, metals, ceramics, resins, magnetic materials, superconductors, and the like, where metal contamination and particle contamination are problems. In particular, it is suitably used for cleaning a semiconductor device substrate surface in a process of manufacturing a semiconductor device substrate such as a semiconductor element or display device, which requires a highly clean substrate surface. Wirings, electrodes, and the like may be present on the surfaces of these substrates. Wiring and electrode materials include Si, Ge, GaAs and other semiconductor materials; SiO₂, Silicon nitride, glass, low dielectric constant material, aluminum oxide, transition metal oxide (titanium oxide, tantalum oxide, hafnium oxide, zirconium oxide, etc.), (Ba, Sr) TiO_ThreeInsulating materials such as (BST), polyimide, and organic thermosetting resin; metals such as W, Cu, and Al, or alloys thereof, silicide, and nitride. The low dielectric constant material is a general term for materials having a relative dielectric constant of 3.5 or less. Incidentally, SiO₂The relative dielectric constant of 3.8 to 3.9.
[0071]
In particular, the cleaning liquid of the present invention is suitably used for cleaning a semiconductor device substrate having a transition metal or a transition metal compound on its surface. Examples of transition metals include W, Cu, Ti, Cr, Co, Zr, Hf, Mo, Ru, Au, Pt, and Ag. Transition metal compounds include nitrides, oxides of these transition metals, oxides, Silicide etc. are mentioned. In these, W and / or Cu are preferable.
[0072]
The step of cleaning the substrate having tungsten on the surface includes cleaning of the substrate surface having a gate electrode and silicon or the like when tungsten is used as a gate electrode material. Specifically, a cleaning step after forming the tungsten film on the semiconductor device, particularly a cleaning step after dry etching the tungsten film, and a cleaning step after ion implantation into the silicon exposed portion are exemplified.
[0073]
If the cleaning liquid of the present invention is used, particles and metals can be removed without performing ultrasonic irradiation or brush scrubbing. Therefore, the cleaning liquid of the present invention has a possibility that the cleaning liquid is broken when ultrasonic cleaning or brush scrubbing is performed, and an extremely fine gate electrode (for example, the width of the gate electrode is about 0.15 μm) is formed with tungsten. It is suitable for cleaning the gate electrode and the substrate surface.
[0074]
The step of cleaning the substrate having Cu on the surface includes cleaning the surface of the substrate having Cu wiring and an interlayer insulating film when Cu is used as a wiring material. Specifically, the cleaning process after forming the Cu film on the semiconductor device, particularly the cleaning process after performing CMP (Chemical Mechanical Polishing) on the Cu film, the hole is formed in the interlayer insulating film on the wiring by dry etching. The cleaning process after opening is mentioned.
[0075]
The cleaning liquid of the present invention is also suitably used for cleaning a semiconductor device substrate having a low dielectric constant material as an interlayer insulating film material on the surface. The low dielectric constant materials are roughly classified into three types: organic polymer materials, inorganic polymer (siloxane-based) materials, and porous (porous) materials. Examples of organic polymer materials include Polyimide, BCB (Benzocyclobutene), Flare (Honeywell), SiLK (Dow Chemical), etc., and inorganic polymer materials include FSG (Fluorinated silicate glass), BLACK DIAMOND (Applied Materials), Aurora (Japan ASM).
[0076]
As described above, the cleaning liquid of the present invention is suitably used for cleaning the surface of a semiconductor device substrate regardless of the presence or absence of electrodes and wiring materials on the substrate surface. Among them, the cleaning liquid of the present invention is preferably used for cleaning a substrate for a semiconductor device exhibiting hydrophobicity with a water contact angle of 60 ° or more on the substrate surface.
[0077]
The method for preparing the cleaning liquid of the present invention may be a conventionally known method. Among the components of the cleaning liquid (for example, surfactant, ammonium hydroxide, water, and other components such as a complexing agent as necessary), any two components or three or more components are blended in advance, and then the remaining components The components may be mixed or all at once.
[0078]
As described above, the substrate cleaning solution for semiconductor devices of the present invention can be applied to a new material in the future, that is, a substrate for a semiconductor device having a metal material having low resistance to chemicals such as hydrogen peroxide on the surface. Therefore, the cleaning liquid can be used in both the pre-process and the post-process, and has an excellent cleaning effect.
[0079]
That is, another gist of the present invention is a substrate cleaning solution for a semiconductor device having at least a semiconductor element electrode or a metal wiring on the surface, characterized by satisfying the following conditions (a), (b) and (c): Exist.
[0080]
(A) The semiconductor element electrode and the metal wiring are not substantially corroded.
(B) The amount of contaminating metal is 1000 to 5000 (× 10¹⁰atoms / cm²), The amount of contaminated metal after cleaning is 10 (× 10¹⁰atoms / cm²)
(C) Particles having a particle size of 0.1 μm or more are 8000 to 100,000 (pieces / 0.03 m).²) When a substantially circular substrate surface having a radius r is cleaned for t (minutes), after cleaning, the number of particles in the circumference on the substrate surface having the same center as the substrate is t = 0.5. In the case of ˜1, it is 200 / t or less within the circumference of the circumferential radius of 0.6r, or 800 / t or less within the circumference of the circumferential radius of 0.9r.
[0081]
The above-mentioned regulations (b) and (c) define the characteristics of the cleaning liquid of the present invention, and do not specify the cleaning conditions under which the cleaning liquid of the present invention is used. Further, in the cleaning liquid of the present invention, “substantially does not corrode the semiconductor element electrode and the metal wiring” means that the semiconductor element electrode and the metal wiring on the substrate to be cleaned, specifically, for example, W, Cu, etc. This means that these materials do not cause adverse effects such as corrosion or alteration on the electrode material or wiring material, and these materials function sufficiently as electrodes or wirings when used as a semiconductor device.
[0082]
In the cleaning liquid of the present invention, satisfying the conditions (b) and (c) indicates that metal contamination, particle contamination, and any contamination can be sufficiently removed.
[0083]
Condition (c) is that when the object to be cleaned is the surface of a substantially disk-shaped substrate, that is, the surface of a substantially circular substrate, the surface of the substrate is highly purified regardless of the position of the substrate surface even if cleaning is performed for a short time. It means you can do it. That is, particles having a particle size of 0.1 μm or more are 8000 to 100,000 (pieces / 0.03 m).²) After cleaning the substantially circular substrate surface having the radius r with the cleaning time t: 0.5 to 1 [minute], the circumferential radius of the relatively inner periphery on the substrate surface having the same center as the substrate is 0. Within the circumference of 6r, the remaining particles are removed up to 200 / t or less, and even within the circumference with a circumference radius of 0.9r including the relatively outer periphery, the particles are reduced to 800 / t. This means that the substrate surface can be highly cleaned.
[0084]
In the above-described semiconductor device substrate cleaning liquid of the present invention, “in the case of cleaning” indicates that the semiconductor device substrate is cleaned with the cleaning liquid by a cleaning method as described later. The cleaning method is not particularly limited as long as it is a method that can be generally employed when cleaning a semiconductor device substrate. Among them, the method of contacting the cleaning liquid with the substrate is preferably a spin type in which the substrate is rotated at high speed while flowing the cleaning liquid on the substrate, and the liquid temperature of the cleaning liquid is preferably in the range of room temperature to 90 ° C. .
[0085]
Further, when cleaning, a cleaning method using physical force, for example, mechanical cleaning such as scrub cleaning using a cleaning brush, ultrasonic cleaning that irradiates a substrate with ultrasonic waves having a frequency of 0.5 megahertz or more, and these are used in combination. By adopting a cleaning method or the like, a more stable cleaning result can be obtained, which is preferable.
[0086]
The cleaning method of the present invention is performed by a method in which a cleaning liquid is brought into direct contact with the substrate. The contact method of the cleaning liquid to the substrate is a dip type in which the cleaning tank is filled with the cleaning liquid and the substrate is immersed, a spin type in which the substrate is rotated at high speed while flowing the cleaning liquid from the nozzle onto the substrate, and the substrate is sprayed and cleaned. A spray type etc. are mentioned. As an apparatus for performing such cleaning, there are a batch-type cleaning apparatus that simultaneously cleans a plurality of substrates housed in a cassette, a single-wafer cleaning apparatus that mounts and cleans a single substrate in a holder, and the like. .
[0087]
In the case of a batch type cleaning apparatus, the cleaning time is usually 30 seconds to 30 minutes, preferably 1 to 15 minutes, and in the case of a single wafer type cleaning apparatus, it is usually 1 second to 15 minutes, preferably 5 seconds to 5 minutes. When the cleaning time is too short, the cleaning effect is not sufficient, and when it is too long, the improvement of the cleaning effect is small and the throughput is reduced. Although the cleaning liquid of the present invention can be applied to any of the above methods, it is preferably used for spin-type or spray-type cleaning because it allows more efficient decontamination in a short time. And if it applies to the single-wafer | sheet-fed washing | cleaning apparatus in which shortening of washing | cleaning time and the reduction of the usage-amount of washing | cleaning liquid are a problem, since these problems are eliminated, it is preferable.
[0088]
The temperature of the cleaning liquid is usually room temperature, but it is preferable to warm to about 40 to 70 ° C. for the purpose of improving the cleaning effect. Further, when cleaning a substrate with silicon exposed on the surface, organic contamination is likely to remain on the silicon surface, so that the substrate is subjected to a heat treatment step at a temperature of 300 ° C. or higher to be thermally decomposed, or ozone water is used. It is preferable to oxidatively decompose organic matter by treatment.
[0089]
The cleaning method of the present invention is preferably used in combination with a cleaning method using physical force, for example, mechanical cleaning such as scrub cleaning using a cleaning brush, or ultrasonic cleaning. In particular, it is preferable to use ultrasonic irradiation or brush scrub in combination because particle contamination can be further improved and cleaning time can be shortened. In particular, it is preferable to use a resin brush for cleaning after CMP.
[0090]
The material of the resin brush can be arbitrarily selected, but for example, PVA (polyvinyl alcohol) is preferably used. In addition, it is preferable to irradiate the substrate with ultrasonic waves having a frequency of 0.5 megahertz or more because particle removability is remarkably improved by a synergistic action with the surfactant. Furthermore, before and / or after the cleaning method of the present invention, cleaning with electrolytic ionic water obtained by electrolysis of water or hydrogen water in which hydrogen gas is dissolved in water may be combined.
[0091]
【Example】
EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not limited by a following example, unless the summary is exceeded.
[0092]
Examples 1 and 2 and Comparative Examples 1 to 3
(Evaluation of cleanability of particle contamination by scrub cleaning)
Low dielectric constant film (SiOC: carbon-containing SiO₂) With an 8-inch silicon substrate (a disk-shaped substrate having a radius r of 4 inches)₂It was immersed in the slurry solution for 10 minutes. The substrate after immersion was washed with ultrapure water for 1 minute and spin-dried with a multi-spinner (“KSSP-201” manufactured by Kaijo Corporation). Thereafter, the number of fine particles adhering to the substrate surface was measured by a laser surface inspection device (“LS-5000” manufactured by Hitachi Electronics Engineering Co., Ltd.), and SiO of 0.2 μm or more was measured.₂It was confirmed that more than a certain number of particles were attached (however, the upper limit was 100,000).
[0093]
Using the cleaning liquid shown in Table 1, with the above multispinner, the above-mentioned SiO with the PVA brush₂The particle-adhered substrate was cleaned with a brush scrub to remove the particles. Washing with the washing solution was performed at room temperature for 1 minute. Thereafter, the substrate was washed with ultrapure water for 1 minute and then spin-dried to obtain a washed substrate. The results are shown in Table 1.
[0094]
[Table 1]

[0095]
Examples 3-6 and Comparative Examples 4-8
(Evaluation of cleanability of particle contamination by scrub cleaning)
First, as in Example 1, SiO 2₂A particle-adhered substrate was prepared. Next, SiO 2 was used as in Example 1 except that the cleaning liquid shown in Table 2 was used and the cleaning time was 0.5 minutes.₂The particle-adhered substrate was washed to obtain a washed substrate. The results are shown in Table 2.
[0096]
The wettability evaluation in Table 2 was performed by the following method. That is, a low dielectric constant film (SiOC: carbon-containing SiO₂The test piece (2 cm square) marked with) is immersed in each cleaning solution shown in Table 2 vertically. After 0.5 minute, the test piece was pulled out vertically and evaluated by the ratio of the area with the cleaning solution to the total area of the test piece. The evaluation criteria were as follows: ○: 80% or more, Δ: 50% or more and less than 80%, ×: less than 50%.
[0097]
[Table 2]

[0098]
Examples 7-10
(Evaluation of cleanability of particle contamination by scrub cleaning)
Low dielectric constant film (SiOC: carbon-containing SiO₂8) silicon substrate (a disk-shaped substrate having a radius r of 4 inches) with a surface treatment with 0.5 wt% hydrofluoric acid for 1 minute, SiO 2₂It was immersed in the slurry solution for 10 minutes. The substrate after immersion was washed with ultrapure water for 1 minute and spin-dried with a multi-spinner (“KSSP-201” manufactured by Kaijo Corporation). Thereafter, the number of fine particles adhering to the substrate surface was measured with a laser surface inspection device (“LS-6600” manufactured by Hitachi Electronics Engineering Co., Ltd.), and SiO1 of 0.11 μm or more was measured.₂It was confirmed that more than a certain number of particles were attached (however, the upper limit was 100,000).
[0099]
Using the cleaning liquid shown in Table 3, the above-mentioned multi-spinner allows the above-mentioned SiO to be brushed with a PVA brush.₂The particle-adhered substrate was cleaned with a brush scrub to remove the particles. Cleaning with the cleaning solution was performed at room temperature for 0.5 minutes. Thereafter, the substrate was washed with ultrapure water for 1 minute and then spin-dried to obtain a washed substrate. The results are shown in Table 3.
[0100]
[Table 3]

[0101]
Examples 11 and 12 and Comparative Example 9
(Evaluation of cleanability of particle contamination by scrub cleaning)
First, as in Example 1, SiO 2₂A particle-adhered substrate was prepared. Next, SiO was used as in Example 1 except that the cleaning liquid shown in Table 4 was used and the cleaning time was 0.5 minutes.₂The particle-adhered substrate was washed to obtain a washed substrate. The results are shown in Table 4.
[0102]
[Table 4]

[0103]
Example 13 and Comparative Example 10
A 4-inch silicon substrate (a disk-shaped substrate having a radius r of 2 inches) with a thermal oxide film having a thickness of about 100 nm on the substrate surface was exposed to the atmosphere for 3 hours to allow airborne substances to adhere. As a result of measurement with a substrate surface inspection apparatus (“LS-5000” manufactured by Hitachi Electronics Engineering Co., Ltd.), 10,000 or more particles (with an upper limit of 100,000) having a particle size of 0.2 μm or more adhered to the substrate. The substrate was immersed in each cleaning solution shown in Table 3 controlled at 50 ° C. for 10 minutes, washed with running water with pure water for 10 minutes, and dried with a spin dryer. Table 5 shows the measurement results of the number of particles remaining on the substrate after the cleaning treatment.
[0104]
Comparative Example 11
In Example 13, as a cleaning solution, a solution (APM cleaning solution) prepared by mixing 29% by weight ammonium hydroxide aqueous solution, 50% by weight hydrogen peroxide water and ultrapure water at a volume ratio of 1: 4: 20. The evaluation was performed in the same manner as in Example 13 except that it was used. The results are shown in Table 5.
[0105]
Although the cleaning liquid of Comparative Example 11 has a relatively small number of adhered particles after cleaning, since the cleaning liquid contains hydrogen peroxide, it cannot be applied to new materials in the future and will not be usable in the future.
[0106]
[Table 5]

[0107]
Example 14 and Comparative Examples 12-14
A 4-inch silicon substrate with a natural oxide film (a disk-shaped substrate having a radius r of 2 inches) was immersed in a 0.5 wt% HF aqueous solution for 5 minutes to obtain a substrate from which the surface oxide film was removed. This was immersed for 10 minutes in each cleaning solution shown in Table 4 to which Silicon (IV) Nitride particles (“Stk # 12145” manufactured by Johnson Matthey) 0.02 g / L was added and the temperature was controlled at 50 ° C. Washing with pure water for 5 minutes was performed, followed by drying with a spin dryer. The number of particles having a particle size of 0.2 μm or more remaining on the substrate after the cleaning treatment was measured with a substrate surface inspection apparatus (“LS-5000” manufactured by Hitachi Electronics Engineering Co., Ltd.). The results are shown in Table 6.
[0108]
[Table 6]

[0109]
Example 15 and Comparative Examples 15 and 16
A 4-inch silicon substrate (a disk-shaped substrate having a radius r of 2 inches) from which the surface natural oxide film was removed by immersion in a 0.5 wt% HF aqueous solution for 5 minutes was prepared. This was immersed in a cleaning solution shown in Table 5 controlled at each temperature for a predetermined time, washed with running pure water for 5 minutes, and dried with a spin dryer. Immediately after drying the substrate, Rms (nm), which is the standard deviation of the Z-axis displacement of the substrate surface, was measured with an atomic force microscope (Digital nbsp; Nano Scope IIIa manufactured by Instruments). The results are shown in Table 7.
[0110]
Visual evaluation is performed on the surface roughness of the substrate. The following results were obtained. That is, in Comparative Examples 15 and 16, innumerable crater-like irregularities having a diameter of about 1 to 10 mm and surface roughness like interference fringes over the entire substrate surface were observed on the substrate surface. Was not observed.
[0111]
[Table 7]

[0112]
Examples 16-19 and Comparative Examples 17-19
A test piece of polycrystalline polysilicon having a film thickness of about 100 nm from which the surface oxide film was removed by immersion in a 0.5 wt% HF aqueous solution for 5 minutes was prepared. This test piece was immersed in each cleaning solution shown in Table 6 controlled at 50 ° C. for 10 minutes, washed with running water with pure water for 5 minutes, and dried with nitrogen blow. The film thickness of the polycrystalline polysilicon was measured with an optical interference type film thickness measuring device ("Nanospec L-6100" manufactured by Nanometrics). The etching rate was calculated from the film thickness measurement before and after the cleaning treatment. The results are shown in Table 8.
[0113]
[Table 8]

[0114]
Example 20, Reference Example 1
A tungsten test piece having a film thickness of about 100 nm from which the surface oxide film was removed by immersing in a 0.3 wt% aqueous ammonia solution for 5 minutes was prepared. This test piece was immersed in each cleaning solution shown in Table 9 controlled in temperature at 40 ° C. for 10 minutes, washed with running pure water for 5 minutes, and dried by nitrogen blowing. The film thickness of tungsten was derived by conversion from the reflection intensity using total reflection fluorescent X-ray (“RIX-3000” manufactured by Jeol). The etching rate was calculated from the film thickness measurement before and after the cleaning treatment. The results are shown in Table 9.
[0115]
Here, as is clear from comparison between Example 20 and Reference Example 1, the cleaning liquid of the present invention is excellent as a substrate cleaning liquid for semiconductor devices by suppressing the etching rate of the substrate surface relative to a simple alkaline aqueous solution. I understand that.
[0116]
Comparative Example 20
In Example 20, evaluation was performed in the same manner as in Example 20 except that the same APM cleaning liquid as in Comparative Example 11 was used as the cleaning liquid. The results are shown in Table 9.
[0117]
[Table 9]

[0118]
Example 21, Comparative Example 21
A 4-inch silicon substrate (a disk-shaped substrate having a radius r of 2 inches) was immersed in an APM cleaning solution containing metal ions (Fe, Cu). In this APM cleaning solution, 29% by weight ammonia water, 31% by weight hydrogen peroxide water and water are mixed at a volume ratio of 1: 1: 5 so that the metal content becomes Fe (20 ppb) and Cu (1 ppm). It was prepared by adding a metal ion-containing aqueous solution. The immersed silicon substrate was washed with ultrapure water for 10 minutes and dried by nitrogen blowing to obtain a silicon substrate contaminated with metal.
[0119]
The analysis of the contaminated metals (Fe, Cu) on the silicon substrate was performed by the following method for both the contaminated silicon substrate and the cleaned silicon substrate. That is, the metal on the substrate surface was recovered by treating the substrate with an aqueous solution containing 0.1% by weight of hydrofluoric acid and 1% by weight of hydrogen peroxide, and the amount of metal was measured by an inductively coupled plasma mass spectrometer (ICP-MS). Is measured and the metal concentration on the substrate surface (atoms / cm²).
[0120]
The silicon substrate contaminated with metal was cleaned by a dip cleaning method using the cleaning liquid shown in Table 10 at a cleaning liquid temperature of 60 ° C. and a cleaning time of 10 minutes. Table 10 shows the analysis result of the contaminated silicon substrate and the residual metal (Fe, Cu) on the surface of the cleaned silicon substrate.
[0121]
[Table 10]

[0122]
From the above results, it is clear that the cleaning liquid of the present invention is excellent in the removability of fine particles (particles) adhering to the hydrophobic low dielectric constant film. Moreover, it turns out that it has the more excellent removability also with respect to the particle deposit | attachment derived from an air suspended substance compared with the conventional washing | cleaning method by an ammonium hydroxide solution or APM solution.
[0123]
Similarly, even when fine particles (particles) or the like are mixed in the system, it is possible to suppress adhesion to the substrate by removing the fine particles with the cleaning method of the present invention. Furthermore, compared to conventional cleaning methods, the roughness (surface roughness) of the silicon surface can be suppressed to an extremely small level even with an alkaline cleaning solution, and side effects such as changes in processing dimensions due to etching into polysilicon or tungsten. Therefore, it is possible to achieve both cleanability, roughness suppression and low etching properties.
[0124]
The cleaning liquid of the present invention is an excellent cleaning that can be used for both the pre-process and the post-process even if it is a substrate for a semiconductor device having a material with low resistance to chemicals such as hydrogen peroxide on its surface. It is clear that the cleaning liquid has an effect.
[0125]
【The invention's effect】
According to the cleaning liquid of the present invention, for semiconductor devices having a semiconductor material such as silicon, an insulating material such as silicon nitride, silicon oxide, glass, and a low dielectric constant material, a transition metal or a transition metal compound, etc. on a part of or the entire surface. In the substrate, fine particles (particles) adhering to the substrate surface, organic contamination, and metal contamination can be effectively removed by cleaning, and adhesion can be suppressed even when fine particles are mixed into the system. In particular, the hydrophobic low dielectric constant material that easily repels chemicals improves the wettability and is excellent in cleanability. Moreover, even in alkaline cleaning liquid, it is possible to achieve both suppression of roughness of silicon surface and low etching property in addition to cleanability, and a surface treatment method for contamination cleaning in the manufacturing process of semiconductor devices, display devices, etc. As industrially very useful.

Claims (13)

After chemically mechanical polishing a semiconductor device substrate having silicon, a transition metal or a transition metal compound on the surface, it contains at least the following components (A), (B) and (C), and has a hydrogen peroxide content: A method for cleaning a substrate for a semiconductor device, wherein the substrate for a semiconductor device is cleaned using a cleaning solution of 10 ppm or less .
Component (A): Polyoxyethylene alkyl ether represented by the following general formula (II)

(However, R ² represents a hydroxyl group, an amino group, an alkoxy group, or an alkyl group which may be substituted with a halogen, the number of carbon atoms (m) contained in the alkyl group is 9 or more, and (n) is 7 And the ratio (m / n) of the number of carbon atoms (m) in the alkyl group to the number of oxyethylene groups (n) in the polyoxyethylene group is 1 to 1.5.
Component (B): Water Component (C): Alkali The cleaning method according to claim 1 , wherein the cleaning liquid further contains a complexing agent. The cleaning method according to claim 1 or 2 , wherein the component (A) has 9 to 16 carbon atoms (m). The method of cleaning according to any one of claims 1 to 3 p H is 9 or more. The cleaning method according to claim 1, wherein the component (C) is an alkali compound represented by the following general formula (I).

(However, R ¹ represents a hydrogen atom, a hydroxyl group, an alkoxy group, or an alkyl group which may be substituted with a halogen, and R ¹ may be the same or different.) The cleaning method according to claim 5 , wherein the component (C) is ammonium hydroxide or quaternary ammonium hydroxide having an alkyl group having 1 to 4 carbon atoms and / or a hydroxyalkyl group. The cleaning method according to any one of claims 1 to 6 , wherein the content of the component (A) is 0.0001 to 1 % by weight. The method of cleaning according to claim 1 for cleaning a substrate while irradiating ultrasonic waves over a frequency 0.5 MHz. The method of cleaning according to any one of claims 1 to 7, the semiconductor device substrate after chemical mechanical polishing brush cleaning. The cleaning method according to claim 1 , wherein the cleaning liquid is heated to a temperature of 40 to 70 ° C. and used. The washing | cleaning method in any one of Claims 1-10 which perform the heat processing of the temperature of 300 degreeC or more, or an ozone water process after wash | cleaning with a washing | cleaning liquid. The cleaning method according to claim 1, which is applied to a substrate for a semiconductor device having an insulating film having a water contact angle of 60 ° or more on the surface. The cleaning method according to claim 1, wherein the transition metal on the surface of the substrate for a semiconductor device is copper .