JP3534847B2 - Method for removing foreign matter adhering to semiconductor wafer - Google Patents
Method for removing foreign matter adhering to semiconductor waferInfo
- Publication number
- JP3534847B2 JP3534847B2 JP24733694A JP24733694A JP3534847B2 JP 3534847 B2 JP3534847 B2 JP 3534847B2 JP 24733694 A JP24733694 A JP 24733694A JP 24733694 A JP24733694 A JP 24733694A JP 3534847 B2 JP3534847 B2 JP 3534847B2
- Authority
- JP
- Japan
- Prior art keywords
- foreign matter
- adhesive
- wafer
- semiconductor wafer
- adhesive layer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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- Cleaning In General (AREA)
- Cleaning Or Drying Semiconductors (AREA)
Description
【発明の詳細な説明】
【0001】
【産業上の利用分野】本発明は、半導体製造プロセスに
おける洗浄工程に適用される、半導体ウエハに付着した
異物の除去方法に関する。
【0002】
【従来の技術】LSIの高密度化、高集積化、また回路
の多様化が進むにつれて、半導体ウエハに存在する塵
埃、金属不純物などの異物(パ―テイクル)が製品の歩
留り、製品の信頼性に大きく影響するようになつてき
た。たとえば、半導体ウエハの表面(回路パタ―ン形成
面)に存在する異物は、回路形成時に回路の断線やシヨ
―トの原因となる。また、半導体ウエハの裏面(回路パ
タ―ン面の反対面)に存在する異物は、回路形成時の露
光工程で焦点を狂わす原因となり、また隣接するウエハ
の表面に転写して回路の断線やシヨ―トの原因となる。
【0003】このため、LSIの製造工程では、製造工
程内の清浄度のレベルアツプ、ウエハ洗浄技術のレベル
アツプに努めており、さまざまな清浄化技術が提案さ
れ、実施されてきた。とくに、洗浄工程は全工程の約3
0%を占めており、歩留りや信頼性アツプのキ―ポイン
トである。しかし、最近のLSIの高密度化、高集積化
に伴い、従来のウエハ洗浄方法の問題が顕在化してき
た。
【0004】ウエハ洗浄方法には、ウエツト洗浄(超純
水、薬液などによる)と、ドライ洗浄(UVオゾン、O
2 プラズマなど)があり、一般にはウエツト洗浄がその
汎用性、経済性のバランスのよさから頻繁に適用され
る。ウエツト洗浄の問題点は、洗浄によりウエハから除
去された異物のウエハへの再付着であり、とくにウエハ
裏面に付着している異物は著しい汚染源となる。また、
ウエツト洗浄は乾燥工程を必要とするため、乾燥工程で
のウエハ汚染の問題が同様に存在する。
【0005】ウエツト洗浄の短所を補う洗浄方法とし
て、洗浄方法のドライ化(UVオゾン、O2 プラズマな
ど)が進んでおり、異物の再付着の低減、乾燥工程の省
略などの利点を活かしているが、ドライ洗浄は異物に対
して十分な除去能力を示さず、多量の汚染物の除去に適
していないことがわかつてきた。
【0006】別の試みとして、特開昭48−35771
号公報などには、粘着テ―プを用いて異物を除去する方
法が提案されている。この方法は、たとえば、ゴム製弾
性ロ―ラの周面に粘着テ―プを巻き付け、これを半導体
ウエハの表面にその上を回転移動させながら押圧接触さ
せることにより、半導体ウエハの表面に付着する異物を
上記テ―プの粘着剤層面に吸着させて除去するものであ
る。
【0007】この粘着テ―プを用いる方法は、一種のド
ライ洗浄ということができるから、ウエツト洗浄におけ
る異物の再付着の問題や乾燥工程での汚染の問題を回避
することができるうえに、UVオゾン、O2 プラズマな
どの他のドライ洗浄に比べ、異物の除去能力をより高め
られるものと期待されている。
【0008】
【発明が解決しようとする課題】しかるに、上記提案の
方法は、粘着テ―プが半導体ウエハに対しロ―ラ周面上
で点接触ないし線接触によりわずか数秒程度接触するだ
けの操作であるため、ウエハ上の異物を粘着剤層面に十
分に吸着させにくい難点がある。
【0009】この欠点は、たとえば、ロ―ラ周面に巻き
付けた粘着テ―プと半導体ウエハとの相対接触速度を可
能な限りおそくしたり、あるいはゴム製弾性ロ―ラの直
径を十分に大きくする、たとえば約2〜3m程度の直径
にすることなどにより、ある程度回避できるものと思わ
れるが、半導体ウエハの生産性や経済性などの点からす
ると実用的ではなく、工業的実施は極めて難しい。
【0010】そこで、上記提案の方法では、実用的な接
触速度および回転ロ―ラの実用的な直径のもとに、粘着
テ―プを巻き付けたロ―ラを半導体ウエハの表面上で何
度も転動させることにより、ウエハ上の異物を粘着剤層
面に十分に吸着させるようにしているが、この場合、一
旦除去された異物が再度半導体ウエハに接触して再付着
するため、異物の除去効率が却つて低下することにな
る。
【0011】本発明は、このような事情に鑑み、ウエツ
ト洗浄方式に比べて有用な粘着テ―プを用いたドライ洗
浄方式により、半導体ウエハに付着した異物を高い除去
率で除去する方法を提供することを目的としている。
【0012】
【課題を解決するための手段】本発明者らは、上記の目
的に対し鋭意検討した結果、粘着テ―プを回転ロ―ラに
巻き付けて押圧操作するのではなく、半導体ウエハ上に
その全面にわたつて貼り付けて、ウエハ上の異物と粘着
剤層面とをある程度の所要時間をもつて十分に馴染ませ
たうえで、剥離操作したときには、ウエハ上の異物を高
い除去率で吸着除去できることを知り、本発明を完成す
るに至つた。
【0013】本発明は、半導体ウエハの表面および/ま
たは裏面の全面に、支持フイルムと粘着剤層とからなる
粘着テ―プを、粘着剤層面が上記表面および/または裏
面の異物と十分に馴染むように貼り付けたのち、この粘
着テ―プを剥離操作することにより、上記異物を粘着剤
層面に吸着させて半導体ウエハから除去する方法であっ
て、かつ、上記の粘着テ―プとして、(a)粘着剤層が
アクリル系樹脂を主成分とし、JIS Z−0237に
準じて測定されるシリコンウエハに対する180度引き
剥がし粘着力(常温、剥離速度300mm/分)が50〜
500g/20mm幅であるものを使用するか、あるい
は、(b)粘着剤層が活性エネルギ―源の供給により特
性が変化する粘着剤であって、上記同様の180度引き
剥がし粘着力が、活性エネルギ−源供給前(貼り付け
時)で500〜2,000g/20mm幅で、活性エネル
ギ−源供給後(剥離操作時)で3〜500g/20mm幅
となるものを使用することにより、0.2μm以上の大
きさの異物を50%以上の除去率で除去することを特徴
とする半導体ウエハに付着した異物の除去方法に係るも
のである。
【0014】
【発明の構成・作用】図1は、本発明に用いる粘着テ―
プの一例を示したものである。1は粘着テ―プで、支持
フイルム11上に粘着剤層12を設けた構成となつてい
る。
【0015】支持フイルム11は、ポリエステル、ポリ
カ―ボネ―ト、ポリ塩化ビニル、エチレン−酢酸ビニル
共重合体、エチレン−エチルアクリレ―ト共重合体、ポ
リエチレン、ポリプロピレン、エチレン−プロピレン共
重合体などのプラスチツクからなる厚さが通常10〜
1,000μmのフイルムである。
【0016】粘着剤層12は、アクリル樹脂系、シリコ
―ン樹脂系、フツ素樹脂系、ゴム系(天然ゴム、合成ゴ
ム)などのポリマ―を主成分とした、常温下で感圧接着
性を有するものであり、厚さは通常5〜100μmであ
る。このような粘着剤層は、上記ポリマ―を主成分とし
た粘着剤を支持フイルム11上に塗着し、加熱などによ
り架橋処理することにより、また離型紙上に上記と同じ
方法で形成した粘着剤層を支持フイルム11上に貼着す
ることにより、形成できる。
【0017】本発明では、粘着テ―プを半導体ウエハに
貼り付けて、半導体ウエハ上の異物を粘着剤層面によく
馴染ませたのち、剥離操作して、上記異物を吸着除去す
ることを基本とする。よつて、粘着剤層12は、貼り
付け時、剥離操作時のそれぞれに適した特性を有して
いる必要がある。しかし、現実には、とで要求され
る特性は、通常相反するものとなる。つまり、の貼り
付け時には、粘着剤は異物に馴染むように塑性変形しや
すく、かつ高粘着力であることが必要であり、一方、
の剥離操作時には、異物を確実に固定するため、粘着剤
は硬く、強靭であり、かつ低粘着力であることが必要で
ある。
【0018】このような特性を実現させる第一の手段
は、,の各段階でバランスよく適合する特性を持つ
た粘着剤を選択することである。この目的には、特性が
比較的安定しているアクリル系樹脂を主成分としたもの
が好ましく用いられる。シリコンウエハに対する粘着力
としては、JIS Z−0237に準じて測定される1
80度引き剥がし粘着力(常温、剥離速度300mm/
分)が、通常50〜500g/20mm幅にあるものが適
している。
【0019】また、第二の手段は、,の各段階で適
合するように、段階ごとに特性を変化させることであ
る。この目的には、活性エネルギ−源の供給により特性
が変化する粘着剤が好ましく用いられる。ここで、活性
エネルギ−源とは、たとえば、紫外線、赤外線(熱)、
電子線、エツクス線などに代表される電磁波、超音波な
どに代表される弾性波のことである。
【0020】上記特性が変化する粘着剤には、紫外線硬
化性粘着剤、電子線硬化性粘着剤、熱硬化性粘着剤、熱
可塑性粘着剤、熱発泡性粘着剤などがあり、それぞれ単
独で用いてもよいし、複数種を同時に用いてもよい。シ
リコンウエハに対する粘着力としては、JIS Z−0
237に準じて測定される180度引き剥がし粘着力
(常温、剥離速度300mm/分)が、活性エネルギ−源
供給前(貼り付け時)で通常500〜2,000g/2
0mm幅であり、活性エネルギ−源供給後(剥離操作時)
で通常3〜500g/20mm幅となるものが適してい
る。
【0021】図2は、上記構成の粘着テ―プ1を用い
て、半導体ウエハに付着した異物を除去する本発明の洗
浄方法を示したものである。まず、半導体ウエハ3の表
面3a(および/または裏面3b)の全面に、粘着テ―
プ1を貼り付けて、粘着剤層12面を上記表面3a上の
異物2に対して十分に馴染ませる。これは、たとえば、
粘着テ―プ1を上記表面3aにハンドロ―ラ(図示せ
ず)により押圧したのち、数分程度放置するといつた方
法で行えばよい。
【0022】このように貼り付けたのち、図示のよう
に、粘着テ―プ1の端部より引き剥がす、剥離操作を施
すと、上記表面3aの異物2は粘着剤層12面に吸着さ
れて、上記表面3aから除去される。その除去率は、従
来のドライ洗浄はもちろんのこと、ウエツト洗浄や既提
案の粘着テ―プを用いる方法に比べて、高い値となる。
一般には、0.2μm以上の大きさの異物を50%以
上、好ましくは70%以上除去できるほどの高い除去率
が得られる。
【0023】この理由は、ウエハ表面の全面にわたり粘
着テ―プを貼り付けて、かつ異物と粘着剤層面とを十分
に馴染ませるようにしたためであり、またその結果とし
て、上記一度の貼り付けおよび剥離操作によつて初期の
除去目的を達成でき、既提案の繰り返し転動による異物
の再付着といつた問題を一切生じないためである。さら
には、粘着剤層として、前記特性を持つたものを使用す
ることにより、剥離操作後に粘着剤がウエハ表面に付着
して、ウエハを汚染するといつた問題を招くおそれも少
ないためである。
【0024】このように半導体ウエハ上の異物を高い除
去率で洗浄除去すると、回路形成時の回路の断線やシヨ
―ト、露光不良発生が低減し、最終的に作製される半導
体デバイスの歩留りや信頼性が大幅に向上する。たとえ
ば、上記歩留りは、従来のウエツト洗浄を適用した場合
よりも、10%以上確実に向上できる。また、地球環境
保全の立場からみて、従来のウエツト洗浄やドライ洗浄
のような純水、薬品、空気、電力などを大量に消費する
洗浄方式を、上記本発明の方式に置き換えることで、地
球環境保全に大きく寄与させることができる。
【0025】
【発明の効果】本発明によれば、粘着テ―プを用いるド
ライ洗浄方式により、半導体ウエハに付着した異物を高
い除去率で除去できるから、半導体デバイスの歩留りや
信頼性の向上に大きく寄与させることができる。また、
従来の他の洗浄方式などに比べて、地球環境保全の面で
の寄与効果も得られる。
【0026】
【実施例】以下に、本発明の実施例を記載して、より具
体的に説明する。
【0027】実施例1
厚さ50μmのポリエステル支持フイルムのコロナ処理
面に、アクリル系粘着剤の溶液を塗布し、120℃で3
分間加熱架橋処理して、厚さ20μmの粘着剤層を有す
る粘着テ―プを作製した。シリコンウエハ(ミラ―面)
に対する粘着力は、JIS Z−0237に準じて測定
される180度引き剥がし粘着力(常温、剥離速度30
0mm/分)で200g/20mm幅であつた。
【0028】0.2μm以上の大きさの異物が0個であ
る5インチシリコンウエハ(回路パタ―ンのないミラ―
ウエハ)を所定の工程(イオン打ち込み処理工程)に通
して異物を付着させ、レ―ザ―表面検査装置〔日立電子
エンジニアリング(株)製のLS−5000;シリコン
ウエハのミラ―面のみ異物数をカウントすることができ
る装置〕を用い、ミラ―面に付着した0.2μm以上の
大きさの異物の数をカウントした。なお、ウエハの表裏
に付着する異物をカウントするため、ミラ―面を表裏逆
にした2通りの場合について同様の検査を行つた。
【0029】異物洗浄試験として、上記のように異物を
付着させたシリコンウエハのミラ―面に、前記の方法で
作製した粘着テ―プを、ハンドロ―ラを用いて貼り付
け、3分間放置したのち、粘着テ―プを剥離操作して、
洗浄した。この洗浄後、再びレ―ザ―表面検査装置を用
いて、ミラ―面に付着している0.2μm以上の大きさ
の異物の数をカウントした。この貼り付けおよび剥離操
作による洗浄後の異物数と、洗浄前の異物数とから、異
物除去率を算出した。
【0030】これとは別に、粘着剤による汚染試験とし
て、0.2μm以上の大きさの異物が0個である5イン
チシリコンウエハ(回路パタ―ンのないミラ―ウエハ)
のミラ―面に、前記の方法で作製した粘着テ―プを、ハ
ンドロ―ラを用いて貼り付け、3分間放置したのち、粘
着テ―プを剥離操作した。この操作後、レ―ザ―表面検
査装置を用いて、ミラ―面に付着している0.2μm以
上の大きさの異物の数をカウントし、粘着剤の付着によ
る汚染状況を調べた。
【0031】なお、上記の異物洗浄試験(異物除去率の
測定)および粘着剤汚染試験(付着異物数の測定)に際
し、一連の作業は、クラス10のクリ―ンル―ム内(温
度23℃、湿度60%)で行つた。これらの試験結果
は、後記の表1(ウエハ表面)および表2(ウエハ裏
面)に示されるとおりであつた。
【0032】実施例2
粘着剤としてアクリル系紫外線硬化性粘着剤を用いたほ
かは、実施例1に準じて厚さ20μmの粘着剤層を有す
る粘着テ―プを作製した。シリコンウエハ(ミラ―面)
に対する粘着力は、JIS Z−0237に準じて測定
される180度引き剥がし粘着力(常温、剥離速度30
0mm/分)で1,050g/20mm幅であつた。また、
紫外線(波長365nm、1,000mj/cm2 )照射後
の上記同様の180度引き剥がし粘着力は、8g/20
mm幅であつた。
【0033】この粘着テ―プを用い、剥離操作前に紫外
線(波長365nm、1,000mj/cm2 )照射処理を
施すようにした以外は、実施例1と同様にして、異物洗
浄試験(異物除去率の測定)および粘着剤汚染試験(付
着異物数の測定)を行つた。これらの試験結果は、後記
の表1(ウエハ表面)および表2(ウエハ裏面)に示さ
れるとおりであつた。
【0034】比較例1
異物洗浄試験として、実施例1と同様の操作により異物
を付着させたシリコンウエハのミラ―面を、超純水洗浄
装置(現行ウエツト洗浄方法)を用いて、所定の条件に
て洗浄した。乾燥後、レ―ザ―表面検査装置を用いて、
ミラ―面に付着している0.2μm以上の大きさの異物
の数をカウントした。この洗浄後の異物数と、洗浄前に
上記同様の装置を用いてカウントした0.2μm以上の
大きさの異物の数とから、異物除去率を算出した。この
試験結果は、後記の表1(ウエハ表面)および表2(ウ
エハ裏面)に示されるとおりであつた。
【0035】比較例2
洗浄方法をUVオゾン洗浄(現行ドライ洗浄)に代えた
ほかは、比較例1に準じて異物洗浄試験を行い、異物除
去率を算出した。この試験結果は、後記の表1(ウエハ
表面)および表2(ウエハ裏面)に示されるとおりであ
つた。
【0036】比較例3
図3に示すように、実施例1で作製した粘着テ―プ1
を、直径50mm、幅180mmのゴム製円筒形弾性ロ―ラ
4の周囲側面に、粘着剤層面を外側にして巻き付け、こ
れを治具5に装着した。実施例1と同様の操作により異
物を付着させたシリコンウエハ3を、シリコンウエハ固
定台6に載置して送り速度40mm/分で走行させなが
ら、その上より上記の弾性ロ―ラ4を回転させながら押
圧操作して、粘着剤層面をウエハ表面に接触させ、1枚
目のシリコンウエハ3Aから2枚目のシリコンウエハ3
Bにかけ連続して洗浄処理した。
【0037】この洗浄後、レ―ザ―表面検査装置を用い
て、ミラ―面に付着している0.2μm以上の大きさの
異物の数をカウントした。この洗浄後の異物数と、洗浄
前に上記同様の装置を用いてカウントした0.2μm以
上の大きさの異物の数とから、異物除去率を算出した。
また、この異物洗浄試験とは別に、粘着剤汚染試験とし
て、実施例1と同様の異物の付着しない5インチシリコ
ンウエハを用いて、これに上記と同様に弾性ロ―ラの回
転により粘着テ―プを押圧接触させたときの汚染状況を
調べた。これらの試験結果は、後記の表1(ウエハ表
面)および表2(ウエハ裏面)に示されるとおりであつ
た。
【0038】
【表1】
【0039】
【表2】
【0040】上記の表1,表2の結果から明らかなよう
に、本発明によれば、シリコンウエハの表面や裏面に付
着した異物を、70%以上の高い除去率で除去できるも
のであることがわかる。とくに実施例2では、粘着剤の
特性である粘着力および粘着剤の硬さを、貼り付け時お
よび剥離操作時の各段階に適するように変化させた、つ
まり貼り付け時は高粘着力で柔らかく、剥離操作時は低
粘着力で硬い特性を持つように設定したことにより、約
80%もの非常に高い除去率が得られることが明らかで
ある。また、実施例1,2のいずれの粘着テ―プにおい
ても、ウエハの汚染程度が少なく、ウエハに付着した異
物を除去するという洗浄目的にほとんど支障をきたさな
いものであることも明らかである。
【0041】これに対し、比較例1,2では、異物除去
率が低く、とくに比較例2では付着した異物はほとんど
除去されていない。また、比較例3では、シリコンウエ
ハ上への粘着テ―プの貼り付けおよび剥離が、シリコン
ウエハ上の任意の点でわずか数秒の間起こつているだけ
のため、粘着剤層表面に異物を十分に吸着させることが
できず、高い異物除去率を望めない。とくに1μm以下
の大きさの異物はほとんど除去されていなかつた。しか
も、2枚目では、1枚目で除去した異物の再付着が認め
られ、異物除去率がさらに低くなつている。
【0042】なお、上記の実施例1,2および比較例1
で示した洗浄方法を、所定の半導体ウエハの製造工程に
適用し、最終的に得られた半導体デバイスの歩留りを集
計した結果、実施例1および実施例2の方法では、比較
例1の方法と比較して、歩留りがそれぞれ12%および
15%高いことがわかつた。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing foreign matter adhering to a semiconductor wafer, which is applied to a cleaning step in a semiconductor manufacturing process. 2. Description of the Related Art As the density and integration of LSIs and the diversification of circuits have advanced, foreign substances (particles) such as dust and metal impurities present on semiconductor wafers have increased product yield and product yield. Has come to greatly affect the reliability. For example, foreign matter present on the surface (circuit pattern forming surface) of a semiconductor wafer causes disconnection or short-circuiting of a circuit during circuit formation. In addition, foreign matter present on the back surface of the semiconductor wafer (opposite to the circuit pattern surface) may cause defocus in the exposure process at the time of circuit formation, and may be transferred to the surface of an adjacent wafer to break the circuit or cause a short circuit. -May cause damage. For this reason, in the LSI manufacturing process, efforts are being made to improve the level of cleanliness in the manufacturing process and the level of the wafer cleaning technology, and various cleaning technologies have been proposed and implemented. In particular, the cleaning process is about 3
It accounts for 0%, which is a key point for improving yield and reliability. However, with the recent high density and high integration of LSI, the problem of the conventional wafer cleaning method has become apparent. [0004] Wafer cleaning methods include wet cleaning (using ultrapure water, chemicals, etc.) and dry cleaning (UV ozone, O
2 ) etc., and wet cleaning is generally applied frequently because of its good balance between versatility and economy. The problem with wet cleaning is the re-adhesion of foreign matter removed from the wafer by the cleaning to the wafer. In particular, foreign matter adhering to the back surface of the wafer is a significant source of contamination. Also,
Since wet cleaning requires a drying step, there is a problem of wafer contamination in the drying step as well. As a cleaning method for compensating for the disadvantages of wet cleaning, dry cleaning methods (UV ozone, O 2 plasma, etc.) have been advanced, and the advantages of reducing the reattachment of foreign substances and omitting the drying step are utilized. However, it has been found that dry cleaning does not show a sufficient ability to remove foreign substances and is not suitable for removing a large amount of contaminants. As another attempt, Japanese Patent Application Laid-Open No. 48-35771
Japanese Patent Laid-Open Publication No. H10-21078 and the like have proposed a method of removing foreign matter using an adhesive tape. According to this method, for example, an adhesive tape is wound around the peripheral surface of a rubber elastic roller, and the adhesive tape is brought into pressure contact with the surface of the semiconductor wafer while being rotationally moved thereon, so that the tape adheres to the surface of the semiconductor wafer. The foreign matter is removed by adsorbing on the surface of the pressure-sensitive adhesive layer of the tape. The method using this adhesive tape can be said to be a kind of dry cleaning, so that the problem of reattachment of foreign substances in wet cleaning and the problem of contamination in the drying step can be avoided and the UV cleaning can be performed. It is expected that the ability to remove foreign substances can be further improved as compared with other dry cleaning such as ozone and O 2 plasma. [0008] However, in the above-mentioned proposed method, the operation is such that the adhesive tape makes contact with the semiconductor wafer by point contact or line contact for only a few seconds on the peripheral surface of the roller. Therefore, there is a problem that it is difficult to sufficiently adsorb foreign substances on the wafer to the surface of the pressure-sensitive adhesive layer. The disadvantage is that, for example, the relative contact speed between the adhesive tape wound around the roller and the semiconductor wafer is made as slow as possible, or the diameter of the rubber elastic roller is made sufficiently large. It can be avoided to some extent, for example, by making the diameter about 2 to 3 m, but it is not practical in terms of the productivity and economics of semiconductor wafers, and industrial implementation is extremely difficult. Therefore, in the above-mentioned method, the roller on which the adhesive tape is wound is repeatedly applied on the surface of the semiconductor wafer based on the practical contact speed and the practical diameter of the rotating roller. The foreign matter on the wafer is sufficiently adsorbed to the surface of the adhesive layer by rolling, but in this case, the foreign matter once removed comes into contact with the semiconductor wafer again and adheres again. Efficiency is instead reduced. In view of such circumstances, the present invention provides a method for removing foreign substances adhering to a semiconductor wafer at a high removal rate by a dry cleaning method using an adhesive tape which is more useful than a wet cleaning method. It is intended to be. Means for Solving the Problems As a result of intensive studies on the above objects, the present inventors have found that, instead of wrapping an adhesive tape around a rotating roller and performing a pressing operation, an adhesive tape is formed on a semiconductor wafer. To the foreign material on the wafer and the pressure-sensitive adhesive layer surface for a certain period of time. Knowing that it can be removed, the present invention has been completed. According to the present invention, an adhesive tape composed of a supporting film and an adhesive layer is sufficiently adapted to the entire surface of the front and / or back surface of the semiconductor wafer so that the surface of the adhesive layer is sufficiently compatible with the foreign matter on the front and / or back surface. After pasting manner, the adhesive tape - by peeling operation the flop, there in a way that removed from the semiconductor wafer by adsorbing the foreign matter on the adhesive layer surface
And, as the above-mentioned adhesive tape, (a) the adhesive layer
Acrylic resin as main component, JIS Z-0237
180 degree pull for silicon wafer measured according to
Peeling strength (normal temperature, peeling speed 300mm / min) 50 ~
Use 500g / 20mm width, or
Is that (b) the pressure-sensitive adhesive layer is more
A pressure-sensitive adhesive that changes its properties.
Peeling adhesive strength before activation energy source supply (pasting
H) at 500-2,000 g / 20 mm width, active energy
3 ~ 500g / 20mm width after feeding the ghee source (during peeling operation)
By using a material that is larger than 0.2 μm
The present invention relates to a method for removing foreign matter attached to a semiconductor wafer, wherein foreign matter having a size is removed at a removal rate of 50% or more . FIG. 1 shows an adhesive tape used in the present invention.
This is an example of a loop. Reference numeral 1 denotes an adhesive tape having a structure in which an adhesive layer 12 is provided on a support film 11. The support film 11 is made of a plastic such as polyester, polycarbonate, polyvinyl chloride, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, polyethylene, polypropylene, ethylene-propylene copolymer and the like. The thickness consisting of usually 10
It is a 1,000 μm film. The pressure-sensitive adhesive layer 12 is mainly composed of a polymer such as an acrylic resin, a silicone resin, a fluorine resin, or a rubber (natural rubber or synthetic rubber). And the thickness is usually 5 to 100 μm. Such a pressure-sensitive adhesive layer is formed by applying a pressure-sensitive adhesive mainly composed of the above-mentioned polymer on the support film 11 and subjecting it to a crosslinking treatment by heating or the like. It can be formed by sticking the agent layer on the support film 11. According to the present invention, the adhesive tape is adhered to the semiconductor wafer, and after the foreign matter on the semiconductor wafer is well adapted to the surface of the adhesive layer, a peeling operation is performed to absorb and remove the foreign matter. I do. Therefore, the pressure-sensitive adhesive layer 12 needs to have characteristics suitable for each of the time of sticking and the time of peeling operation. However, in reality, the required characteristics are usually contradictory. In other words, at the time of sticking, the adhesive must be easily plastically deformed so as to adapt to the foreign matter and have a high adhesive strength.
At the time of the peeling operation, the adhesive must be hard, tough, and have low adhesive strength in order to securely fix the foreign matter. The first means for realizing such characteristics is to select a pressure-sensitive adhesive having characteristics that are well-balanced in each of the steps. For this purpose, a resin mainly composed of an acrylic resin having relatively stable characteristics is preferably used. The adhesive strength to a silicon wafer is measured according to JIS Z-0237.
80 degree peeling adhesive strength (normal temperature, peeling speed 300mm /
Is usually 50 to 500 g / 20 mm width. The second means is to change the characteristics for each stage so as to be adapted at each stage. For this purpose, an adhesive whose properties are changed by the supply of an active energy source is preferably used. Here, the active energy source includes, for example, ultraviolet rays, infrared rays (heat),
It is an electromagnetic wave represented by an electron beam, an Echs line, and the like, and an elastic wave represented by an ultrasonic wave. The pressure-sensitive adhesives having the above-mentioned properties that change include ultraviolet-curable pressure-sensitive adhesives, electron beam-curable pressure-sensitive adhesives, thermosetting pressure-sensitive adhesives, thermoplastic pressure-sensitive adhesives, and heat-foamable pressure-sensitive adhesives. Or a plurality of types may be used at the same time. The adhesive strength to silicon wafer is JIS Z-0
The 180-degree peeling adhesive force (normal temperature, peeling speed 300 mm / min) measured according to 237 is usually 500 to 2,000 g / 2 before supplying the active energy source (at the time of sticking).
0mm width, after supplying active energy source (during peeling operation)
In general, those having a width of 3 to 500 g / 20 mm are suitable. FIG. 2 shows a cleaning method according to the present invention for removing foreign matters adhering to a semiconductor wafer by using the adhesive tape 1 having the above-described structure. First, an adhesive tape is applied to the entire surface 3a (and / or back surface 3b) of the semiconductor wafer 3.
The adhesive layer 12 is sufficiently adhered to the foreign material 2 on the surface 3a by attaching the tape 1. This is, for example,
After the adhesive tape 1 is pressed against the surface 3a by a hand roller (not shown), it may be left in place for a few minutes to perform this method. After sticking in this manner, as shown in the figure, when the tape is peeled off from the end of the adhesive tape 1 and a peeling operation is performed, the foreign matter 2 on the surface 3a is adsorbed on the adhesive layer 12 surface. , From the surface 3a. The removal rate is higher than the conventional dry cleaning, wet cleaning or the method using the already proposed adhesive tape.
In general, a high removal rate is obtained so that foreign matter having a size of 0.2 μm or more can be removed by 50% or more, preferably 70% or more. The reason for this is that the adhesive tape is stuck over the entire surface of the wafer and that the foreign matter and the surface of the pressure-sensitive adhesive layer are sufficiently adapted to each other. This is because the initial removal purpose can be achieved by the peeling operation, and there is no problem of reattachment of the foreign matter due to the repetitive rolling as proposed. Furthermore, by using a material having the above-mentioned properties as the pressure-sensitive adhesive layer, the pressure-sensitive adhesive adheres to the surface of the wafer after the peeling operation, and there is little risk of causing a problem such as contamination of the wafer. When the foreign matter on the semiconductor wafer is washed and removed at a high removal rate as described above, the occurrence of disconnection, short circuit, and exposure failure of the circuit at the time of circuit formation is reduced, and the yield and the yield of the finally manufactured semiconductor device are reduced. The reliability is greatly improved. For example, the yield can be reliably improved by 10% or more as compared with the case where the conventional wet cleaning is applied. Also, from the standpoint of global environmental protection, by replacing the conventional cleaning method, such as wet cleaning and dry cleaning, which consumes a large amount of pure water, chemicals, air, and electric power, with the above-described method of the present invention, It can greatly contribute to conservation. According to the present invention, foreign matter adhering to a semiconductor wafer can be removed at a high removal rate by a dry cleaning method using an adhesive tape, so that the yield and reliability of semiconductor devices can be improved. It can greatly contribute. Also,
As compared with other conventional cleaning methods, a contribution effect on global environmental conservation can be obtained. The present invention will be described in more detail with reference to the following examples. Example 1 A solution of an acrylic pressure-sensitive adhesive was applied to a corona-treated surface of a polyester support film having a thickness of 50 μm, and was applied at 120 ° C. for 3 hours.
The adhesive tape having an adhesive layer having a thickness of 20 μm was prepared by heat-crosslinking treatment for 20 minutes. Silicon wafer (mirror surface)
Adhesive strength to 180 degrees peeling adhesive strength (room temperature, peeling speed 30) measured according to JIS Z-0237
(0 mm / min) and a width of 200 g / 20 mm. 5 inch silicon wafer having no foreign matter having a size of 0.2 μm or more (mirror without circuit pattern)
The wafer is passed through a predetermined process (ion implantation process) to adhere foreign matter, and a laser surface inspection device [LS-5000 manufactured by Hitachi Electronics Engineering Co., Ltd .; Using a device capable of counting], the number of foreign substances having a size of 0.2 μm or more adhering to the mirror surface was counted. In order to count foreign substances adhering to the front and back surfaces of the wafer, the same inspection was performed in two cases where the mirror surface was turned upside down. As a foreign substance cleaning test, the adhesive tape prepared by the above-mentioned method was attached to a mirror surface of a silicon wafer to which foreign substances were attached as described above using a hand roller, and left for 3 minutes. After that, peel off the adhesive tape,
Washed. After this washing, the number of foreign substances having a size of 0.2 μm or more adhering to the mirror surface was counted again using the laser surface inspection device. The foreign substance removal rate was calculated from the number of foreign substances after cleaning by the attaching and peeling operations and the number of foreign substances before cleaning. Separately from this, as a contamination test using an adhesive, a 5-inch silicon wafer (a mirror wafer without a circuit pattern) in which there is no foreign matter having a size of 0.2 μm or more.
The adhesive tape prepared by the above method was adhered to the mirror surface of the above using a hand roller, and after leaving it for 3 minutes, the adhesive tape was peeled off. After this operation, the number of foreign substances having a size of 0.2 μm or more adhering to the mirror surface was counted using a laser surface inspection device, and the contamination status due to the adhesion of the adhesive was examined. In the above foreign substance cleaning test (measurement of foreign substance removal rate) and adhesive contamination test (measurement of the number of adhered foreign substances), a series of operations were performed in a class 10 clean room (at a temperature of 23 ° C., (60% humidity). These test results were as shown in Table 1 (wafer front surface) and Table 2 (wafer back surface) described later. Example 2 An adhesive tape having an adhesive layer having a thickness of 20 μm was prepared in the same manner as in Example 1 except that an acrylic UV-curable adhesive was used as the adhesive. Silicon wafer (mirror surface)
Adhesive strength to 180 degrees peeling adhesive strength (room temperature, peeling speed 30) measured according to JIS Z-0237
(0 mm / min) and a width of 1,050 g / 20 mm. Also,
The same 180 degree peeling strength after irradiation with ultraviolet rays (wavelength 365 nm, 1,000 mj / cm 2 ) is 8 g / 20.
mm width. A foreign matter cleaning test (foreign matter) was carried out in the same manner as in Example 1 except that this adhesive tape was subjected to an ultraviolet ray (wavelength: 365 nm, 1,000 mj / cm 2 ) irradiation treatment before the peeling operation. (Measurement of removal rate) and adhesive contamination test (measurement of the number of adhered foreign substances). These test results were as shown in Table 1 (wafer front surface) and Table 2 (wafer back surface) described later. Comparative Example 1 As a foreign substance cleaning test, a mirror surface of a silicon wafer having foreign substances adhered thereto in the same manner as in Example 1 was subjected to a predetermined condition using an ultrapure water cleaning apparatus (current wet cleaning method). Was washed. After drying, using a laser surface inspection device,
The number of foreign substances having a size of 0.2 μm or more adhering to the mirror surface was counted. The foreign substance removal rate was calculated from the number of foreign substances after the cleaning and the number of foreign substances having a size of 0.2 μm or more counted using the same apparatus as above before the cleaning. The test results were as shown in Table 1 (wafer front surface) and Table 2 (wafer back surface) described later. Comparative Example 2 A foreign substance cleaning test was performed in accordance with Comparative Example 1 except that the cleaning method was changed to UV ozone cleaning (current dry cleaning), and the foreign substance removal rate was calculated. The test results were as shown in Table 1 (wafer front surface) and Table 2 (wafer back surface) described later. Comparative Example 3 As shown in FIG. 3, the adhesive tape 1 produced in Example 1
Was wound around the peripheral side surface of a rubber cylindrical elastic roller 4 having a diameter of 50 mm and a width of 180 mm with the surface of the adhesive layer facing outward, and this was mounted on a jig 5. While the silicon wafer 3 to which foreign matter is adhered by the same operation as in the first embodiment is mounted on the silicon wafer fixing table 6 and travels at a feed speed of 40 mm / min, the elastic roller 4 is rotated from above. And the pressure-sensitive adhesive layer surface is brought into contact with the wafer surface so that the first silicon wafer 3A and the second silicon wafer 3
The resultant was subjected to a washing treatment continuously over B. After this washing, the number of foreign substances having a size of 0.2 μm or more adhering to the mirror surface was counted using a laser surface inspection apparatus. The foreign substance removal rate was calculated from the number of foreign substances after the cleaning and the number of foreign substances having a size of 0.2 μm or more counted using the same apparatus as above before the cleaning.
Separately from this foreign substance cleaning test, as a pressure sensitive adhesive contamination test, a 5-inch silicon wafer to which no foreign substance adheres was used as in Example 1, and the adhesive tape was rotated by rotating an elastic roller as described above. The state of contamination when the pump was brought into pressure contact was examined. These test results were as shown in Table 1 (wafer front surface) and Table 2 (wafer back surface) described later. [Table 1] [Table 2] As is clear from the results of Tables 1 and 2, according to the present invention, it is possible to remove foreign matters adhering to the front and back surfaces of a silicon wafer at a high removal rate of 70% or more. I understand. In particular, in Example 2, the adhesive strength and the hardness of the adhesive, which are the characteristics of the adhesive, were changed so as to be suitable for each stage of the sticking and peeling operations. It is clear that a very high removal rate of about 80% can be obtained by setting the adhesive layer to have a low adhesive strength and a hard property during the peeling operation. It is also clear that the adhesive tapes of Examples 1 and 2 have little contamination of the wafer and hardly hinder the cleaning purpose of removing foreign substances adhering to the wafer. On the other hand, in Comparative Examples 1 and 2, the foreign matter removal rate was low, and particularly in Comparative Example 2, the attached foreign matter was hardly removed. Further, in Comparative Example 3, since sticking and peeling of the adhesive tape on the silicon wafer only occurred for a few seconds at an arbitrary point on the silicon wafer, foreign matters were sufficiently deposited on the surface of the adhesive layer. And a high foreign matter removal rate cannot be expected. In particular, foreign matter having a size of 1 μm or less was hardly removed. Moreover, in the second sheet, re-adhesion of the foreign matter removed in the first sheet is recognized, and the foreign matter removal rate is further reduced. The above Examples 1 and 2 and Comparative Example 1
Was applied to the manufacturing process of a predetermined semiconductor wafer, and the yield of the finally obtained semiconductor devices was totaled. As a result, the methods of Example 1 and Example 2 In comparison, the yields were found to be 12% and 15% higher, respectively.
【図面の簡単な説明】
【図1】本発明に用いる粘着テ―プの一例を示す断面図
である。
【図2】本発明の異物の除去方法の一例を示す断面図で
ある。
【図3】本発明とは異なる異物の除去方法を示す概略側
面図である。
【符号の説明】
1 粘着テ―プ
11 支持フイルム
12 粘着剤層
2 異物
3 半導体ウエハ
3a 半導体ウエハの表面
3b 半導体ウエハの裏面BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing an example of an adhesive tape used in the present invention. FIG. 2 is a cross-sectional view illustrating an example of a method for removing foreign matter according to the present invention. FIG. 3 is a schematic side view showing a method of removing foreign matter different from the present invention. [Description of Signs] 1 Adhesive tape 11 Support film 12 Adhesive layer 2 Foreign material 3 Semiconductor wafer 3a Semiconductor wafer front surface 3b Semiconductor wafer back surface
フロントページの続き (72)発明者 近田 縁 大阪府茨木市下穂積1丁目1番2号 日 東電工株式会社内 (72)発明者 三木 和幸 大阪府茨木市下穂積1丁目1番2号 日 東電工株式会社内 (72)発明者 松村 健 大阪府茨木市下穂積1丁目1番2号 日 東電工株式会社内 (72)発明者 暮石 芳憲 東京都青梅市今井2326番地 株式会社日 立製作所 デバイス開発センタ内 (72)発明者 石川 勉 東京都青梅市今井2326番地 株式会社日 立製作所 デバイス開発センタ内 (72)発明者 高田 仁志 東京都青梅市藤橋3丁目3番地2 日立 東京エレクトロニクス株式会社内 (56)参考文献 特開 平6−232108(JP,A)Continuation of front page (72) Inventor Chika Chikada 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Sun Tokyo Electric Works Co., Ltd. (72) Inventor Kazuyuki Miki 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Sun Tokyo Electric Works Co., Ltd. (72) Inventor Ken Matsumura 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Sun Tokyo Electric Works Co., Ltd. (72) Inventor Yoshinori Gureishi 2326 Imai, Ome City, Tokyo Japan Inside the vertical development device development center (72) Inventor Tsutomu Ishikawa 2326 Imai, Ome City, Tokyo Japan Inside the vertical development device development center (72) Inventor Hitoshi Takada Hitachi 3-3, Fujibashi, Ome City, Tokyo 2 Hitachi Tokyo Electronics Co., Ltd. (56) References JP-A-6-232108 (JP, A)
Claims (1)
の全面に、支持フイルムと粘着剤層とからなる粘着テ―
プを、粘着剤層面が上記表面および/または裏面の異物
と十分に馴染むように貼り付けたのち、この粘着テ―プ
を剥離操作することにより、上記異物を粘着剤層面に吸
着させて半導体ウエハから除去する方法であって、か
つ、上記の粘着テ―プとして、(a)粘着剤層がアクリ
ル系樹脂を主成分とし、JIS Z−0237に準じて
測定されるシリコンウエハに対する180度引き剥がし
粘着力(常温、剥離速度300mm/分)が50〜500
g/20mm幅であるものを使用するか、あるいは、
(b)粘着剤層が活性エネルギ―源の供給により特性が
変化する粘着剤であって、上記同様の180度引き剥が
し粘着力が、活性エネルギ−源供給前(貼り付け時)で
500〜2,000g/20mm幅で、活性エネルギ−源
供給後(剥離操作時)で3〜500g/20mm幅となる
ものを使用することにより、0.2μm以上の大きさの
異物を50%以上の除去率で除去することを特徴とする
半導体ウエハに付着した異物の除去方法。(57) [Claims 1] An adhesive tape comprising a support film and an adhesive layer on the entire surface of the front and / or back surface of a semiconductor wafer.
After the tape is adhered so that the surface of the adhesive layer is sufficiently compatible with the foreign matter on the front surface and / or the back surface, the adhesive tape is peeled off to adsorb the foreign matter on the surface of the adhesive layer, thereby causing the semiconductor wafer to adhere. a method of removing from, or
First, as the above-mentioned adhesive tape, (a) the adhesive layer
As a main component, according to JIS Z-0237.
180 degree peeling of silicon wafer to be measured
Adhesive strength (normal temperature, peeling speed 300mm / min) 50-500
g / 20mm width, or
(B) The adhesive layer has characteristics due to the supply of an active energy source
It is a changing adhesive, and peels 180 degrees as above
The adhesive force before supplying the active energy source (at the time of application)
500-2,000g / 20mm width, active energy source
3 to 500 g / 20 mm width after supply (during peeling operation)
By using the thing, the size of 0.2μm or more
A method for removing foreign matter attached to a semiconductor wafer, wherein the foreign matter is removed at a removal rate of 50% or more .
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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JP24733694A JP3534847B2 (en) | 1994-09-14 | 1994-09-14 | Method for removing foreign matter adhering to semiconductor wafer |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP24733694A JP3534847B2 (en) | 1994-09-14 | 1994-09-14 | Method for removing foreign matter adhering to semiconductor wafer |
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JP3534847B2 true JP3534847B2 (en) | 2004-06-07 |
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Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2007007731A1 (en) | 2005-07-12 | 2007-01-18 | Creative Technology Corporation | Apparatus for removing foreign material from substrate and method for removing foreign material from substrate |
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---|---|---|---|---|
JP5833959B2 (en) | 2011-09-28 | 2015-12-16 | 株式会社Screenホールディングス | Substrate processing apparatus and substrate processing method |
JP2018085481A (en) * | 2016-11-25 | 2018-05-31 | 信越ポリマー株式会社 | Method for regeneration of rubber elastic member |
JP6803798B2 (en) * | 2017-05-11 | 2020-12-23 | 信越ポリマー株式会社 | How to regenerate rubber elastic member |
-
1994
- 1994-09-14 JP JP24733694A patent/JP3534847B2/en not_active Expired - Lifetime
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2007007731A1 (en) | 2005-07-12 | 2007-01-18 | Creative Technology Corporation | Apparatus for removing foreign material from substrate and method for removing foreign material from substrate |
US8196594B2 (en) | 2005-07-12 | 2012-06-12 | Creative Technology Corporation | Apparatus for removing foreign material from substrate and method for removing foreign material from substrate |
Also Published As
Publication number | Publication date |
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JPH0888207A (en) | 1996-04-02 |
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