JP3601892B2 - Adhesive film for backside grinding of semiconductor wafer and method of using the same - Google Patents
Adhesive film for backside grinding of semiconductor wafer and method of using the same Download PDFInfo
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Description
【０００１】
【発明の属する技術分野】
本発明は、半導体ウエハ裏面研削用粘着フィルム及びその使用方法に関する。詳しくは、シリコンウエハ等の半導体ウエハの集積回路が組み込まれた側の面（以下、ウエハ表面という）に貼付して該半導体ウエハの他の面（以下、ウエハ裏面という）を研削し、研削終了後に剥離する半導体ウエハの裏面研削用粘着フィルムであり、温度変化によって粘着力が変化する粘着剤層を有する半導体ウエハ裏面研削用粘着フィルム及びその使用方法に関する。
【０００２】
【従来の技術】
通常、半導体集積回路は、高純度シリコン単結晶等をスライスしてウエハとした後、イオン注入、エッチング等によりその表面に集積回路を形成し、更にウエハの裏面をグライディング、ポリッシング、ラッピング等により研削し、ウエハの厚さを１００〜６００μｍ程度まで薄くしてから、ダイシングしてチップ化する方法で製造されている。これらの工程の中で、半導体ウエハ裏面の研削時に半導体ウエハの破損を防止したり、研削加工を容易にするため、粘着フィルムをその粘着剤層を介してウエハ表面に貼付して保護する方法が用いられている。
【０００３】
粘着フィルムをウエハ表面に貼着してウエハ裏面を研削する場合、該粘着フィルムに求められる性能の一つに、半導体ウエハ表面に対する粘着特性が挙げられる。具体的には、ウエハ裏面研削時には剥離しない程度の高い粘着力を有し、また剥離時には作業性がよく且つ半導体ウエハを破損しない程度の低い粘着力が必要とされている。
【０００４】
しかし、近年、大容量化、高集積化、半導体チップの量産化、小型軽量化等が図られるに伴い、半導体ウエハは大口径化し、また半導体ウエハの厚みはさらに薄く成る傾向があり、半導体ウエハ裏面研削時の表面保護と、剥離の際の作業性、非破損性のバランスを保つことが難しくなってきている。
【０００５】
これらの問題を解決する方法として、例えば、特開昭６０−１８９９３８号公報には、半導体ウエハの裏面を研磨するにあたり、このウエハの表面に感圧性接着フィルムを貼り付け、上記の研磨後この接着フィルムを剥離する半導体ウエハの保護方法において、上記の感圧性接着フィルムが光透過性の支持体とこの支持体上に設けられた光照射により硬化し三次元網状化する性質を有する感圧性接着剤層とからなり、研磨後この接着フィルムを剥離する前にこの接着フィルムに光照射することを特徴とする半導体ウエハの保護方法が開示されている。
【０００６】
しかし、該発明に開示されている光照射により硬化し三次元網状化する性質を有する感圧性接着剤層（粘着剤層）は、ラジカル重合により重合する粘着剤層であるため、ウエハと粘着剤層の間に酸素が入り込んだ場合には、酸素の重合禁止効果により硬化反応が十分に進まず、半導体ウエハ裏面研磨後の剥離時に凝集力の低い未硬化の粘着剤がウエハ表面を汚染することがあった。集積回路が形成された半導体ウエハ表面には複雑な凹凸があり、空気（酸素）を全く挟み込まずに貼付することは不可能である。また、貼付のために酸素を除いた系を作り出すには大掛かりな装置と大きなコストが必要となる。この様な粘着剤層に起因する汚染は、溶剤等による洗浄で除去できる場合もあるが、ほとんどの場合、完全に除去できないのが現状である。
【０００７】
近年、半導体ウエハの大口径化、薄層化およびＩＣの高性能化に伴い、半導体ウエハ表面への汚染が少なく、且つ、ウエハ裏面の研削時や粘着フィルムの剥離時にウエハを破損しない半導体ウエハ裏面研削用粘着フィルム及びその使用方法が望まれている。
【０００８】
【発明が解決しようとする課題】
以上の点に鑑み、本発明の目的は、半導体ウエハの裏面研削時には強い粘着力でウエハ表面を保護し、剥離の際には冷却または加熱することにより粘着力が低下して半導体ウエハを破損させずに剥離することができ、尚かつ、剥離後に粘着剤層からの半導体ウエハ表面に付着する汚染物が殆どない、半導体ウエハの大口径化、薄層化およびＩＣの高性能化に対応できる半導体ウエハ裏面研削用粘着フィルム及びその使用方法を提供することにある。
【０００９】
【課題を解決するための手段】
本発明者らは鋭意検討した結果、結晶性高分子を含み、且つ、温度変化と共に粘着力が劇的に変化する性質を有する粘着剤層が基材フィルムの片面に形成された半導体ウエハ裏面研削用粘着フィルムの中で、特定の粘着力特性を有する粘着フィルムが、上記目的を達成し得て、半導体ウエハの大口径化、薄層化およびＩＣの高性能化に対応できる半導体ウエハ裏面研削用粘着フィルムとして使用できることを見出し、本発明に到った。
【００１０】
具体的には、粘着剤に結晶性高分子を含有させるこにより、特定の温度範囲においてのみウエハ表面を保護するに充分な粘着力を示し、その温度範囲外の低温領域または高温領域では粘着力が低下することを見出し、更に、該温度範囲において貼着、研磨処理を行い、該温度範囲外において剥離処理を行うことにより上記目的が達成し得ることを見出し、本発明に到った。
【００１１】
すなわち、本発明の第１発明は、基材フィルムの片面に粘着剤層が設けられた半導体ウエハ裏面研削用粘着フィルムであって、該粘着剤層が結晶性高分子を含む粘着剤により形成され、該半導体ウエハ裏面研削用粘着フィルムの粘着力が、−１０℃以上の温度における少なくとも一部の温度範囲Ａ〜Ｂ℃（Ａ＜Ｂ）においてのみ１５０〜２，０００ｇ／２５ｍｍであり、且つ、Ａ℃未満の温度領域において１５０ｇ／２５ｍｍ未満であることを特徴とする半導体ウエハ裏面研削用粘着フィルムである。
【００１２】
本発明の第２発明は、基材フィルムの片面に粘着剤層が設けられた半導体ウエハ裏面研削用粘着フィルムであって、該粘着剤層が結晶性高分子を含む粘着剤により形成され、該半導体ウエハ裏面研削用粘着フィルムの粘着力が、７０℃以下の温度における少なくとも一部の温度範囲Ｅ〜Ｆ℃（Ｅ＜Ｆ）においてのみ１５０〜２，０００ｇ／２５ｍｍであり、且つ、Ｆ℃を超える温度領域において１５０ｇ／２５ｍｍ未満であることを特徴とする半導体ウエハ裏面研削用粘着フィルムである。
【００１３】
本発明の第３発明は、半導体ウエハの裏面研削時にその表面に貼着し、研削終了後に剥離する半導体ウエハ裏面研削用粘着フィルムの使用方法であって、該半導体ウエハ裏面研削用粘着フィルムが、基材フィルムの片面に結晶性高分子を含む粘着剤により形成された粘着剤層を有し、その粘着力が−１０℃以上の温度における少なくとも一部の温度範囲Ａ〜Ｂ℃（Ａ＜Ｂ）においてのみ１５０〜２，０００ｇ／２５ｍｍであり、且つ、Ａ℃未満の温度領域において１５０ｇ／２５ｍｍ未満であり、Ａ〜Ｂ℃の温度範囲に含まれる少なくとも一部の温度範囲Ｃ〜Ｄ℃（Ａ＜Ｃ≦Ｄ＜Ｂ、１≦Ｃ≦Ｄ≦６０）においてウエハ表面に該粘着フィルムを貼着し、Ｃ〜Ｄ℃の温度範囲の冷却水をかけながら半導体ウエハの裏面を研削し、次いで、Ａ℃未満に冷却した状態で該粘着フィルムを剥離することを特徴とする半導体ウエハ裏面研削用粘着フィルムの使用方法である。
【００１４】
また、本発明の第４発明は、半導体ウエハの裏面研削時にその表面に貼着し、研削終了後に剥離する半導体ウエハ裏面研削用粘着フィルムの使用方法であって、該半導体ウエハ裏面研削用粘着フィルムが、基材フィルムの片面に結晶性高分子を含む粘着剤により形成された粘着剤層を有し、その粘着力が７０℃以下の温度における少なくとも一部の温度範囲Ｅ〜Ｆ℃（Ｅ＜Ｆ）においてのみ１５０〜２，０００ｇ／２５ｍｍであり、且つ、Ｆ℃を超える温度領域において１５０ｇ／２５ｍｍ未満であり、Ｅ〜Ｆ℃の温度範囲に含まれる少なくとも一部の温度範囲Ｇ〜Ｈ℃（Ｅ＜Ｇ≦Ｈ＜Ｆ、１≦Ｇ）においてウエハ表面に該粘着フィルムを貼着し、Ｇ〜Ｈ℃の温度範囲の冷却水をかけながら半導体ウエハの裏面を研削し、次いで、Ｆ℃を超える温度に加熱した状態で該粘着フィルムを剥離することを特徴とする半導体ウエハ裏面研削用粘着フィルムの使用方法である。
【００１５】
本発明の半導体ウエハ裏面研削用粘着フィルム（以下、粘着フィルムという）は、半導体ウエハの裏面を研削する際には、強い粘着力でウエハ表面に粘着してそれを保護し、ウエハの破損等を防止する。また、剥離する際には、冷却または加熱することにより粘着力を低下させ得るため、剥離を容易にして剥離応力による半導体ウエハの破損を防止することができる。さらに、粘着フィルムを剥離した後には、ウエハ表面に粘着剤層に起因する汚染物が殆ど付着することがなく、ウエハ表面の汚染防止にも優れた効果を発揮する。そのため、本発明によれば、半導体ウエハの大口径化、薄層化、及びＩＣの高性能化に対応できる半導体ウエハ裏面研削用粘着フィルム及びその使用方法が提供される。
【００１６】
【発明の実施の形態】
本発明の粘着フィルムは、基材フィルムに粘着剤層を構成する成分を含有した粘着剤溶液またはエマルジョン液（以下、粘着剤という）を塗布、乾燥して粘着剤層を形成することにより製造される。この場合、環境に起因する汚染等から粘着剤層を保護するために粘着剤層の表面に剥離フィルムを貼着することが好ましい。また、剥離フィルムの片表面に粘着剤を塗布、乾燥して粘着剤層を形成した後、粘着剤層の表面に基材フィルムを貼付して粘着剤層を基材フィルム側に転着する方法によっても製造される。この場合は、粘着剤層を乾燥する際等において粘着剤層表面が汚染されない利点がある。
【００１７】
基材フィルムまたは剥離フィルムのいずれの片表面に粘着剤塗布液等を塗布するかは、基材フィルム及び剥離フィルムの耐熱性、表面張力、半導体ウエハ表面への汚染性等を考慮して決める。例えば、剥離フィルムの耐熱性が基材フィルムのそれより優れている場合は、剥離フィルムの表面に粘着剤層を設けた後、基材フィルムへ転写する。耐熱性が同等または基材フィルムの方が優れている場合は、基材フィルムの表面に粘着剤層を設け、その表面に剥離フィルムを貼付する。しかし、粘着フィルムは、剥離フィルムを剥離したときに露出する粘着剤層の表面を介して半導体ウエハ表面に貼付されることを考慮し、粘着剤層による半導体ウエハ表面の汚染防止を図るためには、耐熱性の良好な剥離フィルムを使用し、その表面に粘着剤塗布液を塗布、乾燥して粘着剤層を形成する方法が好ましい。
【００１８】
本発明の半導体ウエハ裏面研削用粘着フィルムの使用方法は、特定の温度範囲において粘着剤層を介して半導体ウエハの表面に貼着し、ウエハ表面を保護してウエハ裏面を研削し、次いで、該温度範囲外に冷却または加熱して粘着剤層の温度を該温度範囲外とした後に剥離する方法である。
【００１９】
先ず、本発明の粘着フィルムの製造方法について説明する。
本発明の粘着フィルムは、通常、基材フィルムの片表面に粘着剤を塗布、乾燥して粘着剤層を形成する方法、または、剥離フィルムの片表面に粘着剤を塗布、乾燥して粘着剤層を形成した後、基材フィルムの片表面に転着する方法により製造される。
【００２０】
基材フィルムまたは剥離フィルムの片表面に粘着剤を塗布する方法としては、従来公知の塗布方法、例えば、ロールコーター法、リバースロールコーター法、グラビアロールコーター法、バーコーター法、コンマコーター法、ダイコーター法等が採用できる。また、粘着剤を塗布する方法の他に、基材フィルムと粘着剤層を共押出しする方法も挙げられる。粘着剤層や基材フィルム等の性質に応じて、これらの方法でも適宜選択できる。
【００２１】
本発明の粘着フィルムに用いる基材フィルムとして、合成樹脂、天然ゴム、合成ゴム等から製造されたフィルムが挙げられる。具体的に例示するならば、エチレン−酢酸ビニル共重合体、エチレン−メタクリル酸共重合体、ポリブタジエン、軟質塩化ビニル樹脂、ポリオレフィン、ポリエステル、ポリアミド、アイオノマー等の樹脂、およびそれらの共重合体エラストマー、およびジエン系、ニトリル系、シリコーン系、アクリル系等の合成ゴム等のフィルムが挙げられる。基材フィルムは単層体であっても、また、積層体であってもよい。
【００２２】
基材フィルムの厚みは、半導体ウエハ裏面を研削する際のウエハの破損防止、ウエハ表面への貼付作業性および剥離作業性等に影響する。かかる観点から、基材フィルムの厚みは、通常、１０〜２０００μｍである。好ましくは１００〜３００μｍである。基材フィルムの厚み精度は、粘着フィルムの厚み精度に影響を与え、ひいては裏面研削後の半導体ウエハの厚み精度に影響を与える。従って、基材フィルムは上記範囲の厚みにおいて±５μｍ以内の精度で作成されたものが好ましい。さらに好ましくは±３μｍ以内である。
【００２３】
裏面を研削する際の半導体ウエハの破損防止を考慮すると、基材フィルムの硬度は、ＡＳＴＭ−Ｄ−２２４０に規定されるショアーＤ型硬度が４０以下である樹脂をフィルム状に成形加工した弾性フィルム、例えば、エチレン−酢酸ビニル共重合体フィルム、ポリブタジエンフィルム等が好ましく用いられる。この場合、基材フィルムの粘着剤層が設けられる面の反対側の面に、これより硬いフィルム、具体的には、ショアーＤ型硬度が４０を超える樹脂をフィルム状に成形加工したフィルムを積層することが好ましい。そのことにより、粘着フィルムの剛性が増し、貼付作業性及び剥離作業性が改善される。
【００２４】
また、半導体ウエハの裏面を研削した後に施される酸によるエッチング処理の際にも引続き、半導体ウエハ裏面研削用粘着フィルムを貼付して半導体ウエハの表面を保護する場合には、耐酸性に優れた基材フィルムを使用することが好ましい。耐酸性フィルムを基材フィルムの粘着剤層と反対側に積層してもよい。耐酸性のフィルムしては、例えばポリプロピレンフィルム等が挙げられる。
基材フィルムと粘着剤層との接着力を向上させるため、基材フィルムの粘着剤層を設ける面にはコロナ放電処理または化学処理等を施すことが好ましい。また、基材フィルムと粘着剤層の間に下塗り剤を用いてもよい。
【００２５】
本発明の粘着フィルムの粘着剤表面に配設する剥離フィルムとして、ポリプロピレン、ポリエチレンテレフタレート等の合成樹脂フィルムが挙げられる。必要に応じてその表面にシリコーン処理等が施されたものが好ましい。剥離フィルムの厚みは、通常１０〜２０００μｍである。好ましくは３０〜１００μｍである。
【００２６】
本発明の粘着フィルムに設ける粘着剤層は、結晶性高分子を含有し、特定の温度範囲において、半導体ウエハ表面を保護するに十分な粘着力を示す粘着剤によって形成される。
粘着剤の具体例としては、例えば、特表平６−５１０５４８号公報（国際公開番号：ＷＯ９２／１３９０１）に記載されている粘着剤が好ましい。すなわち、通常、粘着テープ等の粘着剤層に使用されている粘着剤組成物（以下、通常の粘着剤という）と結晶性高分子との混合物である。通常、その混合割合は、通常の粘着剤約５０〜９９．７重量部に対して、結晶性高分子が約０．３〜５０重量部の範囲で混合することが好ましい。より好ましくは、通常の粘着剤約６５〜９５重量部に対して、結晶性高分子が約５〜３５重量部であり、さらに好ましくは、通常の粘着剤約７０〜９０重量部に対して、結晶性高分子が約１０〜３０重量部であり、最も好ましくは、通常の粘着剤約７０〜８０重量部に対して結晶性高分子が約２０〜約３０重量部である。
【００２７】
通常の粘着剤としては、天然ゴム系粘着剤、並びに、スチレン−ブタジエン共重合体系粘着剤、及び、炭素数１〜９のアルキル基を有するポリアクリル酸アルキルエステルまたはその共重合体等のアクリル系粘着剤等の合成ゴム系粘着剤等が挙げられ、これらは単独でも２種以上の混合物であってもよい。
【００２８】
これらの通常の粘着剤は架橋剤を用いて凝集力や粘着力特性を調整する必要がある場合には、架橋点となりうる官能基を有していることが好ましい。官能基としてはカルボキシル基、水酸基、アミノ基等が挙げられる。またこれらの通常の粘着剤には、適宜、可塑剤、粘着付与剤、安定剤等を混合してもよい。
【００２９】
結晶性高分子としては、側鎖結晶性高分子、主鎖結晶性高分子等が挙げられる。粘着力の温度変化への依存性を考慮すると前者の方が好ましい。側鎖結晶性高分子としては、重合性炭素−炭素２重結合をもつ１種以上の単量体であって、重合した際に結晶化が可能となる側鎖を有する単量体（以下、ＳＣＣ単量体と称する）を重合して得られる重合体または共重合体、並びに、ＳＣＣ単量体及びＳＣＣ単量体と共重合可能な他の単量体とを共重合して得られる共重合体が挙げられる。ＳＣＣ単量体は単独で使用してもよいし、２種以上を混合して使用してもよい。また、ＳＣＣ単量体と共重合可能な他の単量体も２種以上を混合して使用してもよい。
【００３０】
これらのＳＣＣ単量体として、炭素数１０〜５０の脂肪族基を有するアクリレート、メタクリレート、アクリルアミド誘導体、メタクリルアミド誘導体、ビニルエーテル誘導体、ビニルエステル誘導体、少なくとも一部がフッ素置換された炭素数６〜５０の脂肪族基を有するアクリレート、メタクリレート、アクリルアミド誘導体、メタクリルアミド誘導体、ビニルエーテル誘導体、ビニルエステル誘導体、並びに、炭素数８〜２４のアルキル基を有するスチレン誘導体から選ばれた少なくとも１種の単量体等が挙げられる。
【００３１】
これらの内、粘着特性の温度依存性、重合反応性等を考慮すると、炭素数１４〜５０の線状脂肪族基を有するアクリレート、メタクリレート、アクリルアミド誘導体、メタクリルアミド誘導体等が好ましい。さらに好ましくは、炭素数１４〜２２の線状脂肪族基を有するアクリレート、メタクリレート、アクリルアミド誘導体、メタクリルアミド誘導体等である。
上記のＳＣＣ単量体と共重合可能な他の単量体としては、炭素数が１〜９のアルキル基を有するアクリル酸アルキルエステルまたはメタクリル酸アルキルエステル、酢酸ビニル、アクリロニトリル、スチレン等が挙げられる。
【００３２】
架橋剤を用いて凝集力や粘着力特性を調整する必要がある場合等を考慮すると、側鎖結晶性高分子には、架橋点となり得る官能基を有する単量体を共重合することが好ましい。架橋点となり得る官能基を有する単量体として、アクリル酸、メタクリル酸、イタコン酸、メサコン酸、シトラコン酸、フマル酸、マレイン酸、イタコン酸モノアルキルエステル、メサコン酸モノアルキルエステル、シトラコン酸モノアルキルエステル、フマル酸モノアルキルエステル、マレイン酸モノアルキルエステル、アクリル酸２−ヒドロキシエチル、メタクリル酸２−ヒドロキシエチル、アクリルアミド、メタクリルアミド、ターシャル−ブチルアミノエチルアクリレート、ターシャル−ブチルアミノエチルメタクリレート等が挙げられる。
【００３３】
また、アクリル酸グリシジル、メタクリル酸グリシジル、イソシアネートエチルアクリレート、イソシアネートエチルメタクリレート、２−（１−アジリジニル）エチルアクリレート、２−（１−アジリジニル）エチルメタクリレート等の自己架橋性の官能基を持った単量体、さらには、ジビニルベンゼン、アクリル酸ビニル、メタクリル酸ビニル、アクリル酸アリル、メアクリル酸アリル等の多官能性の単量体を組み合わせてもよい。
【００３４】
粘着フィルムの粘着力特性を考慮すると、側鎖結晶性高分子は、結晶性側鎖の質量の合計が、結晶性高分子全体の質量の５０重量％以上になるように合成することが好ましい。より好ましくは６５重量％以上である。
【００３５】
側鎖結晶性高分子を重合する方法としては、溶液重合法、懸濁重合法、乳化重合法等既知の様々な方法が採用できる。重合反応機構としては、ラジカル重合、アニオン重合、カチオン重合等が挙げられるが、粘着剤の製造コスト等を等慮すればラジカル重合によって重合することが好ましい。ラジカル重合反応によって重合する際、ラジカル重合開始剤として、ベンゾイルパーオキサイド、アセチルパーオキサイド、イソブチリルパーオキサイド、オクタノイルパーオキサイド、ジ−ターシャル−ブチルパーオキサイド、ジ−ターシャル−アミルパーオキサイド等の有機過酸化物、過硫酸アンモニウム、過硫酸カリウム、過硫酸ナトリウム等の無機過酸化物、２，２’−アゾビスイソブチロニトリル、２，２’−アゾビス−２−メチルブチロニトリル、４，４’−アゾビス−４−シアノバレリックアシッド等のアゾ化合物等が挙げられる。これらは、得られる側鎖結晶性高分子の性質、重合方法に応じて適宜選択される。
【００３６】
側鎖結晶性高分子としては、上記重合体の他に、結晶性側鎖を有するものであれば、ポリエステル系、ポリエーテル系、ポリアミド系、ポリエチレンイミン系、シリコーン系等の高分子等が挙げられる。
また、主鎖結晶性高分子としては、水不溶性ポリアルキレンオキシド、低級アルキルポリエステル、ポリアミド、ナイロン、ポリテトラヒドロフラン、及び一般式（１）〔化１〕
【００３７】
【化１】
【００３８】
粘着特性の温度依存性、半導体ウエハ表面への汚染性を考慮すると、上記結晶性高分子は３，５００から９００，０００程度の分子量を有するものが好ましい。これらの結晶性高分子の分子量は、特に粘着特性の温度依存性に影響を与え、分子量によって、ウエハの表面に貼着した際にウエハの表面を保護するに充分な粘着力を示す温度範囲（以下、この温度範囲をＡ〜Ｂ℃の温度範囲、または、Ｅ〜Ｆ℃の温度範囲という）が異なる傾向にある。例えば、結晶性高分子の分子量が大きくなるに従い、温度範囲の上限ＢまたはＦの値が大きくなる傾向があり、特に、第２および第４発明の場合、分子量が大きくなりすぎると、粘着剤層とウエハ表面の間に化学的な相互作用（ウエハ表面の腐食、汚染等）を引き起こす温度、粘着剤層の分解温度、基材フィルムの軟化温度等、を越える温度に加熱しても粘着フィルムを剥離することが出来なくなることがある。従って、結晶性高分子の分子量は半導体ウエハの裏面研削工程における温度条件（冷却水の温度、剥離時の温度等）、ウエハ表面への汚染性等を考慮して決定する必要がある。
【００３９】
例えば、Ｅ〜Ｆ℃の温度範囲においてのみウエハの表面を保護するに充分な粘着力を示す粘着剤が形成された粘着フィルムを、Ｆ℃の温度範囲外に加熱して剥離する場合、分子量は３，５００から２５，０００程度の範囲に調整することが好ましく、より好ましくは、３，５００から１２，０００程度の範囲である。
【００４０】
また、Ａ〜Ｂ℃の温度範囲においてのみウエハの表面を保護するに充分な粘着力を示す粘着剤が形成された粘着フィルムを、Ａ℃の温度範囲外に冷却によって剥離する場合には、何れの分子量でも特に問題はないが、ウエハ表面への汚染性を考慮するとより高い分子量が好ましく、従って２５，０００から９００，０００程度の範囲に調整することが好ましく、より好ましくは、１００，０００から９００，０００程度の範囲である。
【００４１】
通常の粘着剤と結晶性高分子の混合物は、粘着力特性、凝集力の調整、ウエハ表面への汚染性等を考慮して、必要に応じて、架橋させてもよい。ウエハの凹凸の状態によっても異なるが、ウエハ裏面研削後、冷却してから粘着フィルムを剥離する場合、架橋させた方が、粘着力が低下し易くなる傾向がある。架橋方法としては、架橋剤による架橋、光や放射線等による架橋等既知の架橋方法の中から適宜選択することができるが、架橋方法の簡便さを考慮すると架橋剤による架橋が好ましい。
【００４２】
架橋剤としては、テトラメチレンジイソシアネート、ヘキサメチレンジイソシアネート、トリメチロールプロパンのトルエンジイソシアネート３付加物、ポリイソシアネート等のイソシアネート系化合物、ソルビトールポリグリシジルエーテル、ポリグリセロールポリグリシジルエーテル、ペンタエリスリトールポリグリシジルエーテル、ジグリセロールポリグリシジルエーテル、グリセロールポリグリシジルエーテル、ネオペンチルグリコールジグリシジルエーテル、レソルシンジグリシジルエーテル等のエポキシ系化合物、トリメチロールプロパン−トリ−β−アジリジニルプロピオネート、テトラメチロールメタン−トリ−β−アジリジニルプロピオネート、Ｎ，Ｎ’−ジフェニルメタン−４，４’−ビス（１−アジリジンカルボキシアミド）、Ｎ，Ｎ’−ヘキサメチレン−１，６−ビス（１−アジリジンカルボキシアミド）、Ｎ，Ｎ’−トルエン−２，４−ビス（１−アジリジンカルボキシアミド）、トリメチロールプロパン−トリ−β−（２−メチルアジリジン）プロピオネート等のアジリジン系化合物、及びヘキサメトキシメチロールメラミン等のメラミン系化合物等が挙げられる。これらは単独で使用してもよいし、２種以上を併用してもよい。
【００４３】
架橋剤の添加量は、粘着剤層に求められる粘着特性、凝集力、通常の粘着剤および結晶性高分子の性質等により異なるが、通常、通常の粘着剤と結晶性高分子の混合物１００重量部に対して０．０１〜３０重量部の範囲で適宜選択される。
【００４４】
粘着剤層の厚みは、半導体ウエハの表面状態、形状、裏面の研削方法等により適宣決められるが、半導体ウエハの裏面を研削している時の粘着力、研削が完了した後の剥離性等を勘案すると、通常２〜１００μｍ程度である。好ましくは５〜７０μｍである。
【００４５】
上記のようにして得られる本発明の粘着フィルムは、半導体ウエハ表面に粘着フィルムを貼着する工程から該ウエハ裏面の研削工程を経て粘着フィルムを剥離する工程の直前に到るまでの間、ウエハ表面にしっかりと貼着してウエハ表面を保護するに充分な粘着力を有する粘着フィルムである。ここで、ウエハ表面を保護するに充分な粘着力とは、ウエハ裏面の研作中に剥離したり、ウエハ表面と粘着剤層との間に冷却水の侵入が生じない程度の粘着力のことであり、具体的には、ＪＩＳ Ｚ ０２３７に規定される方法に準拠して、被着体としてＳＵＳ３０４−ＢＡ板を用い、剥離速度３００ｍｍ／ｍｉｎ．、剥離角度１８０度の条件下で測定した粘着力が所定の温度において、通常、１５０〜２０００ｇ／２５ｍｍの範囲内であることを意味する。好ましくは２００〜２０００ｇ／２５ｍｍの範囲内である。
【００４６】
かくして、上記の如くして製造される本発明に係わる粘着フィルムは、−１０℃以上の温度における少なくとも一部の温度範囲Ａ〜Ｂ℃（Ａ＜Ｂ）においてのみ１５０〜２，０００ｇ／２５ｍｍの粘着力を示し、且つ、Ａ℃未満の温度領域に冷却することにより、その粘着力が１５０ｇ／２５ｍｍ未満に低下するものである。温度範囲Ａ〜Ｂ℃（Ａ＜Ｂ）における好ましい粘着力は２００〜２０００ｇ／２５ｍｍである。Ａ℃未満の温度領域における好ましい粘着力は８０ｇ／２５ｍｍ以下である。また、好ましいＡ〜Ｂ℃の温度範囲は、１０℃以上の温度範囲における少なくとも一部の温度範囲である。ここで、「−１０℃以上の温度範囲」に於ける上限の温度には特に制限はないが、実質的には基材フィルムが加熱により軟化し、本発明で定義する粘着力の測定が事実上不可能となる温度であり、具体的には、ＪＩＳ Ｋ ２２０７（環球法）に準拠して測定した基材フィルムの原料樹脂（即ちフィルム化前の樹脂）の軟化温度＋５０℃程度の温度が挙げられる。基材フィルムが融点を有する場合は融点程度の温度が上限温度である。
【００４７】
また、本発明の他の発明に係わる粘着フィルムは、７０℃以下の温度における少なくとも一部の温度範囲Ｅ〜Ｆ℃（Ｅ＜Ｆ）においてのみ１５０〜２，０００ｇ／２５ｍｍの粘着力を示し、且つ、Ｆ℃を超える温度領域に加熱することにより、その粘着力が１５０ｇ／２５ｍｍ未満に低下するものである。好ましくは、Ｅ〜Ｆ℃の温度範囲は、６０℃以下の温度における少なくとも一部の温度範囲である。温度範囲Ｅ〜Ｆ℃（Ｅ＜Ｆ）における好ましい粘着力は２００〜２０００ｇ／２５ｍｍである。Ｆ℃を超える温度領域における好ましい粘着力は８０ｇ／２５ｍｍ以下である。ここで、「７０℃以下の温度範囲」に於ける下限の温度には特に制限はないが、実質的には、基材フィルムが冷却により脆性を示すようになり、本発明で定義する粘着力の測定が事実上不可能となる温度である。具体的には、ＡＳＴＭ Ｄ−７４６に準拠して測定した基材フィルムの原料樹脂（即ちフィルム化前の樹脂）の脆化温度−１００℃程度の温度が挙げられる。
【００４８】
さらに、実際の作業性を考慮すると、上記のいずれの粘着フィルムついても、少なくとも２０〜２５℃の温度範囲内において、ウエハ表面を保護するに充分な粘着力を示すものであることが好ましい。さらに好ましくは少なくとも１５〜３０℃の温度範囲内においてウエハ表面を保護するに充分な粘着力を示すものである。
【００４９】
次いで、本発明の半導体ウエハ裏面研削用粘着フィルムの使用方法について説明する。第１の方法として、粘着フィルムの粘着剤層から剥離フィルムを剥離して粘着剤層表面を露出させ、その粘着剤層を介して集積回路が形成された側の半導体ウエハの表面に、−１０℃以上の温度における少なくとも一部の温度範囲Ａ〜Ｂ℃（Ａ＜Ｂ）の温度範囲に含まれる少なくとも一部の温度範囲Ｃ〜Ｄ℃（Ａ＜Ｃ≦Ｄ＜Ｂ、１≦Ｃ≦Ｄ≦６０）においてウエハ表面に粘着フィルムを貼着し、粘着フィルムの基材フィルム側を介して研削機のチャックテーブル等に半導体ウエハを固定し、Ｃ〜Ｄ℃の温度範囲の冷却水をかけながら半導体ウエハの裏面を研削し、次いで、Ａ℃未満に冷却した状態で該粘着フィルムを剥離する方法が挙げられる。
【００５０】
ウエハ表面に粘着フィルムを貼着し、且つ、冷却水の温度である上記Ｃ〜Ｄ℃の温度範囲は、１０≦Ｃ≦Ｄ≦４０であることが好ましい。半導体ウエハ表面を保護するに十分な粘着力を示す温度範囲に管理するために、研削中の冷却水の温度、研削室温等をＣ〜Ｄ℃の範囲内で管理する必要がある。剥離温度は、Ａ℃未満ならば、任意の温度でよいが、実際の作業性を考慮すると、通常、−３０℃以上が好ましい。
【００５１】
また、第２の方法として、粘着フィルムの粘着剤層から剥離フィルムを剥離して粘着剤層表面を露出させ、その粘着剤層を介して集積回路が形成された側の半導体ウエハの表面に、７０℃以下の温度に含まれる少なくとも一部の温度範囲Ｇ〜Ｈ℃（Ｅ＜Ｇ≦Ｈ＜Ｆ、１≦Ｇ）においてウエハ表面に該粘着フィルムを貼着し、粘着フィルムの基材フィルム側を介して研削機のチャックテーブル等に半導体ウエハを固定し、Ｇ〜Ｈ℃の温度範囲の冷却水をかけながら半導体ウエハの裏面を研削し、次いで、Ｆ℃を超える温度に加熱した状態で該粘着フィルムを剥離する方法が挙げられる。
【００５２】
ウエハ表面に粘着フィルムを貼着し、且つ、冷却水の温度である上記Ｇ〜Ｈ℃の温度範囲は、１０≦Ｇ≦Ｈ≦４０であることが好ましい。半導体ウエハ表面を保護するに十分な粘着力を示す温度範囲に管理するために、研削中の冷却水の温度、研削室温等をＧ〜Ｈ℃の範囲内で管理する必要がある。剥離温度は、Ｆ℃を超える温度ならば任意の温度でよいが、通常、粘着剤層とウエハ表面の間に化学的な相互作用（ウエハ表面の腐食、汚染等）を引き起こす温度、粘着剤層の一部が分解し始める温度、または基材フィルムの軟化温度の何れの温度をも超えない様にすることが好ましい。具体的には、通常、基材フィルムの軟化温度が１００℃以下の場合にはその軟化温度未満、基材フィルムの軟化温度が１００℃を超える場合には、１００℃以下の温度で剥離することが好ましい。
【００５３】
本発明の粘着フィルムの粘着力は、研削する半導体ウエハの口径、研削時間、半導体ウエハの表面形状、研削後の厚み等種々を考慮して上記範囲内に適宜調整することができる。
半導体ウエハ裏面を研削する装置、器具等、及び研削方法には特に制限はなく公知の方法が適用できる。半導体ウエハ裏面の研削が完了した後、粘着フィルムを剥離する前にケミカルエッチング工程を経ることもある（この場合、ケミカルエッチング層はＡ〜Ｂ℃、またはＥ〜Ｆ℃の範囲内に管理する必要がある。好ましくはＣ〜Ｄ℃、またはＧ〜Ｈ℃である。
本発明が適用できる半導体ウエハとして、シリコンウエハのみならず、ゲルマニウム、ガリウム−ヒ素、ガリウム−リン、ガリウム−ヒ素−アルミニウム等のウエハが挙げられる。
【００５４】
【実施例】
以下、実施例を示して本発明についてさらに詳細に説明する。
以下に示す実施例及び比較例の中で、半導体ウエハ裏面研削用粘着フィルムの製造（粘着剤塗布液の調製以降）および半導体ウエハ裏面研削用粘着フィルムを用いた半導体ウエハの裏面研削は全て米国連邦規格２０９ｂに規定されるクラス１，０００以下のクリーン度に維持された環境において実施した。
本発明はこれら実施例に限定されるものではない。
尚、本実施例において使用された通常の粘着剤（アクリル系粘着剤）、および結晶性高分子（側鎖結晶性高分子）の合成は、下記調製例１〜４の方法に従って行った。また、得られた粘着フィルムの性能および該フィルムを用いた半導体ウエハ裏面研削方法における各特性は、下記（１）〜（３）の方法により評価した。
【００５５】
（１）裏面研削時の半導体シリコンウエハの破損数（枚数）
集積回路が形成された半導体シリコンウエハ（径：８インチ、厚み：６００μｍ、表面の凹凸：約１０μｍ）の表面に、それぞれの実施例および比較例で得られた粘着フィルムを貼付し、研削機〔（株）ディスコ製：バックグラインダーＤＦＧ−８２１Ｆ／８〕を用いて，所定の水温の水をかけて冷却しながら半導体シリコンウエハの裏面を該ウエハの厚みが２００μｍになるまで研削する。研削終了後、所定の条件下で該フィルムを剥離する。各実施例および比較例毎に半導体シリコンウエハを２０枚使用し、研削を２０回行い、裏面研削中に破損したウエハの枚数（研削中の粘着フィルムの剥離が原因）、粘着フィルムと半導体ウエハの間に水の侵入があったウエハの枚数、剥離時に破損したウエハの枚数を計数する。
【００５６】
（２）顕微鏡による半導体ウエハへの汚染性の観察（％）
上記（１）における半導体ウエハ裏面研削中、及び、粘着フィルムの剥離時に破損しなかったウエハに対して、ウエハ表面の集積回路を光学顕微鏡（（株）ニコン製：ＯＰＴＩＰＨＯＴ２）を用いて５０〜１０００倍の範囲でウエハ表面全体及び回路の微細部分まで観察し、汚染されているチップの割合を評価する。
【００５７】
（３）粘着力（ｇ／２５ｍｍ）特性
基本的な操作はＪＩＳ Ｚ ０２３７に記載される方法に準拠し、下記条件下で実施する。
実施例及び比較例で得られた粘着フィルムをその粘着剤層を介して、ＳＵＳ３０４−ＢＡ板（縦：２０ｃｍ、横：５ｃｍ）の表面に貼付し、２３℃において３０分間放置する。放置後、試料の一端を挟持し、剥離角度：１８０度、剥離速度：３００ｍｍ／ｍｉｎ．で所定の温度においてＳＵＳ３０４−ＢＡ板の表面から試料を剥離し、剥離する際の応力を測定してｇ／２５ｍｍに換算する。
【００５８】
調製例１
＜アクリル系粘着剤（以下、高分子１）の合成＞
アクリル酸ブチル９１重量部、アクリロニトリル４．５重量部、アクリル酸４．５重量部をトルエン１５０重量部中で、開始剤として２，２’−アゾビス−イソブチロニトリル（以下、ＡＩＢＮという）１重量部を用いて窒素雰囲気下８０℃において共重合して、高分子１の溶液（固形分４０重量％）を得た。
【００５９】
調製例２
＜側鎖結晶性高分子その１（以下、高分子２）の合成＞
メタクリル酸ヘキサデシル９８重量部、アクリル酸２重量部をトルエン１８０重量部中でドデシルメルカプタン５重量部の存在下で、開始剤としてＡＩＢＮ１重量部を用いて窒素雰囲気下８０℃において共重合して、高分子２の溶液（固形分３６重量％）を得た。
【００６０】
調製例３
＜側鎖結晶性高分子その２（以下、高分子３）の合成＞
アクリル酸オクタデシル９８重量部、アクリル酸２重量部をトルエン１８０重量部中でドデシルメルカプタン５重量部の存在下で、開始剤としてＡＩＢＮ１重量部を用いて窒素雰囲気下８０℃において共重合して、高分子３の溶液（固形分３６重量％）を得た。
【００６１】
調製例４
＜側鎖結晶性高分子その３（以下、高分子４）の合成＞
メタクリル酸ヘキサデシル９８重量部、アクリル酸２重量部を酢酸エチル１８０重量部中で、開始剤としてＡＩＢＮ０．２重量部を用いて窒素雰囲気下７５℃において共重合して、高分子４の溶液（固形分３６重量％）を得た。
【００６２】
実施例１
調製例１で合成した高分子１の溶液（固形分４０重量％）７５重量部、及び、調製例２で合成した高分子２の溶液（固形分３６重量％）２５重量部を混合し、さらに、イソシアネート系架橋剤（三井東圧化学（株）製、オレスターＰ４９−６０ＳＸ、固形分６０重量％）１重量部を添加して粘着剤塗布液を得た。この粘着剤塗布液をロールコーターを用いてポリプロピレンフィルム（剥離フィルム、厚み：５０μｍ）の片面に塗布し、１２０℃で１分間乾燥して厚さ１５μｍの粘着剤層を設けた。次いで、コロナ放電処理を施した厚さ１２０μｍのエチレン−酢酸ビニル共重合体フィルム（ショアーＤ型硬度：３８）の該処理面を貼り合わせ押圧して、粘着剤層を転写させることにより粘着フィルムを製造した。
【００６３】
室温が２３℃に管理された環境下で、得られた粘着フィルムの粘着剤層から剥離フィルムを剥離し、粘着剤層表面を露出させ、その粘着剤層を介して、集積回路が形成された半導体シリコンウエハ（径：８インチ、厚み６００μｍ、表面の凹凸差：約１０μｍ）の表面に貼付し、研削機〔（株）ディスコ製：バックグラインダーＤＦＧ−８２１Ｆ／８〕を用いて，２３℃の水をかけて冷却しながら半導体シリコンウエハの裏面をウエハの厚みが２００μｍになるまで研削した。研削終了後、該ウエハを該フィルムを貼着したまま５℃に冷却し、この温度を保持したまま該フィルムを剥離した。２０枚の半導体ウエハについて同様の操作を２０回行った。研削中に破損したウエハ、ウエハと粘着フィルムの間に水の侵入があったウエハ、および、剥離時に破損したウエハは皆無であった。得られた粘着フィルムの実施例１の使用条件下での粘着力特性および半導体ウエハ表面への汚染性、並びに、研削結果を〔表１〕に示す。
【００６４】
実施例２
実施例１で得られた粘着フィルムを用いて、実施例１と同様の環境下において、冷却水の水温を３０℃とした以外は実施例１と同様の方法で、集積回路が形成された半導体シリコンウエハ（実施例１と同じ）の裏面をウエハの厚みが２００μｍになるまで研削した。研削終了後、該ウエハを該フィルムを貼着したまま１０℃に冷却し、この温度を保持したまま該フィルムを剥離した。２０枚の半導体ウエハについて同様の操作を２０回行った。研削中に破損したウエハ、ウエハと粘着フィルムの間に水の侵入があったウエハ、および、剥離時に破損したウエハは皆無であった。実施例１の粘着フィルムの実施例２の使用条件下での粘着力特性および半導体ウエハ表面への汚染性、並びに、研削結果を〔表１〕に示す。
【００６５】
実施例３
調製例１で合成した高分子１の溶液（固形分４０重量％）７５重量部、及び、調製例３で合成した高分子３の溶液（固形分３６重量％）２５重量部を混合し、さらに、イソシアネート系架橋剤（三井東圧化学（株）製、オレスターＰ４９−６０ＳＸ、固形分６０重量％）２重量部を添加して粘着剤塗布液を得た。この粘着剤塗布液を用いて、実施例１と同様の方法で粘着フィルムを製造した。
【００６６】
得られた粘着フィルムを用い、実施例１と同様の環境下において、実施例１と同様の方法で、集積回路が形成された半導体シリコンウエハ（実施例１と同じ）の裏面をウエハの厚みが２００μｍになるまで研削した。研削終了後、該ウエハを該フィルムを貼着したまま６５℃に加熱し、この温度を保持したまま該フィルムを剥離した。２０枚の半導体ウエハについて同様の操作を２０回行った。研削中に破損したウエハ、ウエハと粘着フィルムの間に水の侵入があったウエハ、および、剥離時に破損したウエハは皆無であった。得られた粘着フィルムの実施例３の使用条件下での粘着力特性および半導体ウエハ表面への汚染性、並びに、研削結果を〔表１〕に示す。
【００６７】
実施例４
実施例３で得られた粘着フィルムを用いて、実施例１と同様の環境下において、冷却水の水温を４０℃とした以外は実施例１と同様の方法で、集積回路が形成された半導体シリコンウエハ（実施例１と同じ）の裏面をウエハの厚みが２００μｍになるまで研削した。研削終了後、該ウエハを該フィルムを貼着したまま５５℃に加熱し、この温度を保持したまま該フィルムを剥離した。２０枚の半導体ウエハについて同様の操作を２０回行った。研削中に破損したウエハ、ウエハと粘着フィルムの間に水の侵入があったウエハ、および、剥離時に破損したウエハは皆無であった。実施例３の粘着フィルムの実施例４の使用条件下での粘着力特性および半導体ウエハ表面への汚染性、並びに、研削結果を〔表１〕に示す。
【００６８】
実施例５
調製例１で合成した高分子１の溶液（固形分４０重量％）７０重量部、及び、調製例４で合成した高分子４の溶液（固形分３６重量％）３０重量部を混合し、さらに、イソシアネート系架橋剤（三井東圧化学（株）製、オレスターＰ４９−６０ＳＸ、固形分６０重量％）１．５重量部を添加して粘着剤塗布液を得た。この粘着剤塗布液を用いて、実施例１と同様の方法で粘着フィルムを製造した。
【００６９】
得られた粘着フィルムを用い、実施例１と同様の環境下において、実施例１と同様の方法で、集積回路が形成された半導体シリコンウエハ（実施例１と同じ）の裏面を該ウエハの厚みが２００μｍになるまで研削した。研削終了後、実施例１と同様の方法で該フィルムを剥離した。２０枚の半導体ウエハについて同様の操作を２０回行った。研削中に破損したウエハ、ウエハと粘着フィルムの間に水の侵入があったウエハ、および、剥離時に破損したウエハは皆無であった。得られた粘着フィルムの実施例５の使用条件下での粘着力特性および半導体ウエハ表面への汚染性、並びに、研削結果を〔表１〕に示す。
【００７０】
実施例６
実施例５で得られた粘着フィルムを用いて、実施例１と同様の環境下において、冷却水の水温を４０℃とした以外は実施例１と同様の方法で、集積回路が形成された半導体シリコンウエハ（実施例１と同じ）の裏面をウエハの厚みが２００μｍになるまで研削した。研削終了後、実施例２と同様の方法で該フィルムを剥離した。２０枚の半導体ウエハについて同様の操作を２０回行った。研削中に破損したウエハ、ウエハと粘着フィルムの間に水の侵入があったウエハ、および、剥離時に破損したウエハは皆無であった。実施例５の粘着フィルムの実施例６の使用条件下での粘着力特性および半導体ウエハ表面への汚染性、並びに、研削結果を〔表１〕に示す。
【００７１】
【表１】
比較例１
実施例１で得られた粘着フィルムを用いて、実施例１と同様の環境下において、実施例１と同様の方法で、集積回路が形成された半導体シリコンウエハ（実施例１と同じ）の裏面をウエハの厚みが２００μｍになるまで研削した。研削終了後、冷却せずにそのまま該フィルムを剥離した。２０枚の半導体ウエハについて同様の操作を２０回行った。研削中に破損したウエハおよびウエハと粘着フィルムの間に水の侵入があったウエハは皆無であったが、剥離時に１１枚のウエハが破損した。実施例１の粘着フィルムの比較例１の使用条件下での粘着力特性および半導体ウエハ表面への汚染性、並びに、研削結果を〔表２〕に示す。
【００７３】
比較例２
実施例３で得られた粘着フィルムを用いて、実施例１と同様の環境下において、実施例１と同様の方法で、集積回路が形成された半導体シリコンウエハ（実施例１と同じ）の裏面をウエハの厚みが２００μｍになるまで研削した。研削終了後、加熱せずにそのまま該フィルムを剥離した。２０枚の半導体ウエハについて同様の操作を２０回行った。研削中に破損したウエハおよびウエハと粘着フィルムの間に水の侵入があったウエハは皆無であったが、剥離時に４枚のウエハが破損した。実施例３の粘着フィルムの比較例２の使用条件下での粘着力特性および半導体ウエハ表面への汚染性、並びに、の研削結果を〔表２〕に示す。
【００７４】
比較例３
実施例５で得られた粘着フィルムを用いて、実施例１と同様の環境下において、実施例１と同様の方法で、集積回路が形成された半導体シリコンウエハ（実施例１と同じ）の裏面をウエハの厚みが２００μｍになるまで研削した。研削終了後、冷却せずにそのまま該フィルムを剥離した。２０枚の半導体ウエハについて同様の操作を２０回行った。研削中に破損したウエハおよびウエハと粘着フィルムの間に水の侵入があったウエハは皆無であったが、剥離時に１０枚のウエハが破損した。実施例５の粘着フィルムの比較例３の使用条件下での粘着力特性および半導体ウエハ表面への汚染性、並びに、研削結果を〔表２〕に示す。
【００７５】
比較例４
５℃の環境下において、実施例１で得られた粘着フィルムを、その粘着剤層を介して、集積回路が形成された半導体シリコンウエハ（実施例１と同じ）の表面に貼付したところ、粘着力がほとんどなく貼付できなかった。結果を〔表２〕に示す。
【００７６】
比較例５
実施例３で得られた粘着フィルムを６５℃に加熱し、そのままの温度で、その粘着剤層を介して、集積回路が形成された半導体シリコンウエハ（実施例１と同じ）の表面に貼付したところ、すぐに半導体ウエハ周辺からフィルムが浮き上がりが始め、ウエハの裏面研削が不可能な状態となった。結果を〔表２〕に示す。
【００７７】
比較例６
５℃の環境下において、実施例５で得られた粘着フィルムを、その粘着剤層を介して、集積回路が形成された半導体シリコンウエハ（実施例１と同じ）の表面に貼付したところ、粘着力がほとんどなく貼付できなかった。結果を〔表２〕に示す。
【００７８】
比較例７
実施例１で得られた粘着フィルムを用いて、実施例１と同様の環境下において、冷却水の水温を１０℃とした以外は実施例１と同様の方法で、集積回路が形成された半導体シリコンウエハ（実施例１と同じ）の裏面をウエハの厚みが２００μｍになるまで研削した。研削終了後、該ウエハを該フィルムを貼着したまま１０℃に維持し、この温度を保持したまま該フィルムを剥離した。２０枚の半導体ウエハについて同様の操作を２０回行った。研削中に１０枚のウエハが破損し、破損のなかった残りの全てのウエハ（１０枚）にウエハと粘着フィルムの間に水の侵入が認められた。この水侵入の認められたウエハから該テープを剥離した時のウエハの破損は皆無であった。実施例１の粘着フィルムの比較例７の使用条件下での粘着力特性および半導体ウエハ表面への汚染性、並びに、研削結果を〔表２〕に示す。
【００７９】
比較例８
実施例３で得られた粘着フィルムを用いて、実施例１と同様の環境下において、冷却水の水温を５５℃とした以外は実施例１と同様の方法で、集積回路が形成された半導体シリコンウエハ（実施例１と同じ）の裏面をウエハの厚みが２００μｍになるまで研削した。研削終了後、該ウエハを該フィルムを貼着したまま５５℃に維持し、この温度を保持したまま該フィルムを剥離した。２０枚の半導体ウエハについて同様の操作を２０回行った。研削中に１１枚のウエハが破損し、破損のなかった残りの全てのウエハ（９枚）にウエハと粘着フィルムの間に水の侵入が認められた。この水侵入の認められたウエハから該テープを剥離した時のウエハの破損は皆無であった。実施例３の粘着フィルムの比較例８の使用条件下での粘着力特性および半導体ウエハ表面への汚染性、並びに、研削結果を〔表２〕に示す。
【００８０】
比較例９
実施例５で得られた粘着フィルムを用いて、実施例１と同様の環境下において、冷却水の水温を１０℃とした以外は実施例１と同様の方法で、集積回路が形成された半導体シリコンウエハ（実施例１と同じ）の裏面をウエハの厚みが２００μｍになるまで研削した。研削終了後、該ウエハを該フィルムを貼着したまま１０℃に維持し、この温度を保持したまま該フィルムを剥離した。２０枚の半導体ウエハについて同様の操作を２０回行った。研削中に１０枚のウエハが破損し、破損のなかった残りの全てのウエハ（１０枚）にウエハと粘着フィルムの間に水の侵入が認められた。この水侵入の認められたウエハから該テープを剥離した時のウエハの破損は皆無であった。実施例５の粘着フィルムの比較例９の使用条件下での粘着力特性および半導体ウエハ表面への汚染性、並びに、研削結果を〔表２〕に示す。
【００８１】
【表２】
比較例１０
調製例１で合成した高分子１の溶液（固形分４０重量％）１００重量部にイソシアネート系架橋剤（三井東圧化学（株）製、オレスターＰ４９−６０ＳＸ、固形分６０％）１．２重量部を添加して粘着剤塗布液を得た。この粘着剤塗布液をロールコーターを用いてポリプロピレンフィルム（剥離フィルム、厚み：５０μｍ）に塗布し、１２０℃で１分間乾燥して厚さ１５μｍの粘着剤層を設けた。次いで、コロナ放電処理を施した厚さ１２０μｍのエチレン−酢酸ビニル共重合体フィルム（ショアーＤ型硬度：３８）の該処理面を貼り合わせ押圧して、粘着剤層を転写させることにより粘着フィルムを製造した。
【００８３】
実施例１と同様の環境下において、実施例１と同様の方法で、集積回路が形成された半導体シリコンウエハ（実施例１と同じ）の裏面をウエハの厚みが２００μｍになるまで研削した。研削終了後、該ウエハを該フィルムを貼着したまま５℃に冷却し、この温度を保持したまま該フィルムを剥離した。２０枚の半導体ウエハについて同様の操作を２０回行った。研削中に破損したウエハおよびウエハと粘着フィルムの間に水の侵入があったウエハは皆無であったが、剥離時に１３枚のウエハが破損した。得られた粘着フィルムの比較例１０の使用条件下での粘着力特性および半導体ウエハ表面への汚染性、並びに、研削結果を〔表３〕に示す。
【００８４】
比較例１１
比較例１０で得られた粘着フィルムを用いて、実施例１と同様の環境下において、実施例１と同様の方法で、集積回路が形成された半導体シリコンウエハ（実施例１と同じ）の裏面をウエハの厚みが２００μｍになるまで研削した。研削終了後、該ウエハを該フィルムを貼着したまま６５℃に加熱し、この温度を保持したまま該フィルムを剥離した。２０枚の半導体ウエハについて同様の操作を２０回行った。研削中に破損したウエハおよびウエハと粘着フィルムの間に水の侵入があったウエハは皆無であったが、剥離時に４枚のウエハが破損した。得られた粘着フィルムの比較例１１の使用条件下での粘着力特性および半導体ウエハへの汚染性、並びに、研削結果を〔表３〕に示す。
【００８５】
比較例１２
比較例１０で得られた粘着フィルムを用いて、実施例１と同様の環境下において、実施例１と同様の方法で、集積回路が形成された半導体シリコンウエハ（実施例１と同じ）の裏面をウエハの厚みが２００μｍになるまで研削した。研削終了後、室温で該フィルムを剥離した。２０枚の半導体ウエハについて上記の操作を２０回行った。研削中に破損したウエハおよびウエハと粘着フィルムの間に水の侵入があったウエハは皆無であったが、剥離時に１０枚のウエハが破損した。得られた粘着フィルムの比較例１２の使用条件下における粘着力特性および半導体ウエハへの汚染性、並びに、研削結果を〔表３〕に示す。
【００８６】
比較例１３
調製例１で合成した高分子１の溶液（固形分４０重量％）１００重量部にイソシアネート系架橋剤（三井東圧化学（株）製、オレスターＰ４９−６０ＳＸ、固形分６０％）６．５重量部を添加して粘着剤塗布液を得た。この粘着剤塗布液をロールコーターを用いてポリプロピレンフィルム（剥離フィルム、厚み：５０μｍ）に塗布し、１２０℃で１分間乾燥して厚さ１５μｍの粘着剤層を設けた。次いで、コロナ放電処理を施した厚さ１２０μｍのエチレン−酢酸ビニル共重合体フィルム（ショアーＤ型硬度：３８）の該処理面を貼り合わせ押圧して、粘着剤層を転写させることにより粘着フィルムを製造した。
【００８７】
実施例１と同様の環境下において、実施例１と同様の方法で、集積回路が形成された半導体シリコンウエハ（実施例１と同じ）の裏面をウエハの厚みが２００μｍになるまで研削した。研削終了後、室温で該フィルムを剥離した。２０枚の半導体ウエハについて、同様の操作を２０回行った。研削中に３枚のウエハが破損し、破損のなかった残りの全てのウエハ（１７枚）にウエハと粘着フィルムの間に水の侵入が認められた。この水侵入の認められたウエハから該テープを剥離した時のウエハの破損は皆無であった。得られた粘着フィルムの比較例１３の使用条件下における粘着力特性および半導体ウエハ表面への汚染性、並びに、研削結果を〔表３〕に示す。
【００８８】
比較例１４
調製例１で合成した高分子１の溶液（固形分４０重量％）１００重量部にイソシアネート系架橋剤（三井東圧化学（株）製、オレスターＰ４９−６０ＳＸ、固形分６０％）２重量部、ジペンタエリスリトールモノヒドロキシペンタアクリレート６重量部およびα−ヒドロキシシクロヘキシルフェニルケトン０．４重量部を添加して粘着剤塗布液を得た。この粘着剤塗布液をロールコーターを用いてポリプロピレンフィルム（剥離フィルム、厚み：５０μｍ）に塗布し、１２０℃で１分間乾燥して厚さ１５μｍの粘着剤層を設けた。次いで、コロナ放電処理を施した厚さ１２０μｍのエチレン−酢酸ビニル共重合体フィルム（ショアーＤ型硬度：３８）の該処理面を貼り合わせ押圧して、粘着剤層を転写させることにより粘着フィルムを製造した。
【００８９】
実施例１と同様の環境下において、実施例１と同様の方法で、集積回路が形成された半導体シリコンウエハ（実施例１と同じ）の裏面をウエハの厚みが２００μｍになるまで研削した。研削終了後、粘着フィルムのエチレン−酢酸ビニル共重合体フィルム側から高圧水銀ランプ（４０Ｗ／ｃｍ）で１５ｃｍの距離から２０秒間光照射した後、室温で該フィルムを剥離した。２０枚の半導体ウエハについて同様の操作を２０回行った。研削中に破損したウエハ、ウエハと粘着フィルムの間に水の侵入があったウエハ、および、剥離時に破損したウエハは皆無であった。しかし、顕微鏡による観察で、一部の回路のアルミ電極上に粘着剤に起因する汚染物が観察された。得られた粘着フィルムの比較例１４の使用条件下における粘着力特性および半導体ウエハ表面への汚染性、並びに、研削結果を〔表１〕に示す。
【００９０】
【表３】
【発明の効果】
本発明の半導体ウエハ裏面研削用粘着フィルムは、結晶性高分子を含む粘着剤層が形成されており、半導体ウエハの裏面を研削する際には強い粘着力で半導体ウエハを保護し、剥離するの際には冷却または加熱する等の簡単な操作で容易に粘着力が低下する。そのため、研削操作中には、半導体ウエハと粘着フィルムの間に冷却水が侵入することがない上、半導体ウエハが破損することがない。また、剥離応力が小さいので剥離する際に半導体ウエハが破損することがない。さらに、剥離した後に粘着剤層からの汚染物が半導体ウエハ表面に付着することが殆どない。従って、半導体ウエハの大口径化、薄層化およびＩＣの高性能化にある当技術分野において優れた効果を発揮するものである。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an adhesive film for grinding a back surface of a semiconductor wafer and a method for using the same. More specifically, a semiconductor wafer such as a silicon wafer is attached to a surface (hereinafter, referred to as a wafer surface) of the semiconductor wafer on which the integrated circuit is incorporated, and the other surface of the semiconductor wafer (hereinafter, referred to as a wafer back surface) is ground. The present invention relates to an adhesive film for grinding a back surface of a semiconductor wafer, which is an adhesive film for peeling a semiconductor wafer later and has an adhesive layer whose adhesive force changes with a change in temperature, and a method of using the same.
[0002]
[Prior art]
Normally, a semiconductor integrated circuit is formed by slicing a high-purity silicon single crystal or the like into a wafer, forming an integrated circuit on the surface by ion implantation, etching, or the like, and then grinding the back surface of the wafer by gliding, polishing, lapping, or the like. Then, the wafer is manufactured by a method in which the thickness of the wafer is reduced to about 100 to 600 μm, and then the wafer is diced into chips. In these processes, there is a method of protecting the semiconductor wafer by attaching the adhesive film to the wafer surface via the adhesive layer in order to prevent damage to the semiconductor wafer when grinding the back surface of the semiconductor wafer or to facilitate the grinding process. Used.
[0003]
When a pressure-sensitive adhesive film is adhered to the surface of a wafer and the back surface of the wafer is ground, one of the performances required for the pressure-sensitive adhesive film is an adhesive property to the surface of the semiconductor wafer. Specifically, it is required to have a high adhesive strength that does not peel when grinding the back surface of the wafer, and a low adhesive force that has good workability and does not damage the semiconductor wafer when peeling.
[0004]
However, in recent years, as the capacity, the degree of integration, the mass production of semiconductor chips, and the size and weight of semiconductor chips have been increased, the diameter of semiconductor wafers has increased, and the thickness of semiconductor wafers has tended to be further reduced. It is becoming difficult to maintain a balance between surface protection during back grinding, workability during peeling, and non-breakability.
[0005]
As a method for solving these problems, for example, in Japanese Patent Application Laid-Open No. 60-189938, when polishing the back surface of a semiconductor wafer, a pressure-sensitive adhesive film is attached to the surface of the wafer, and after polishing, the adhesive In a method for protecting a semiconductor wafer from which a film is peeled off, the pressure-sensitive adhesive film has a light-transmitting support and a pressure-sensitive adhesive having a property of being hardened by light irradiation provided on the support to form a three-dimensional network. A method for protecting a semiconductor wafer comprising a layer and irradiating the adhesive film with light after polishing and before peeling the adhesive film is disclosed.
[0006]
However, since the pressure-sensitive adhesive layer (adhesive layer) having the property of being cured by light irradiation and forming a three-dimensional network as disclosed in the invention is an adhesive layer polymerized by radical polymerization, the wafer and the adhesive When oxygen enters between the layers, the curing reaction does not proceed sufficiently due to the effect of inhibiting polymerization of oxygen, and the uncured adhesive with low cohesive force contaminates the wafer surface during peeling after polishing the backside of the semiconductor wafer. was there. There are complicated irregularities on the surface of the semiconductor wafer on which the integrated circuit is formed, and it is impossible to attach the semiconductor wafer without sandwiching air (oxygen) at all. In addition, a large-scale apparatus and a large cost are required to create a system from which oxygen is removed for application. Such contamination caused by the pressure-sensitive adhesive layer can be removed by washing with a solvent or the like in some cases, but in most cases it cannot be completely removed in most cases.
[0007]
In recent years, as semiconductor wafers have become larger in diameter, thinner, and ICs have higher performance, the surface of the semiconductor wafer is less contaminated, and the wafer is not damaged when the wafer is ground or the adhesive film is peeled off. Adhesive film for grinding and method of using the same But Is desired.
[0008]
[Problems to be solved by the invention]
In view of the above points, an object of the present invention is to protect the wafer surface with strong adhesive force when grinding the back surface of a semiconductor wafer, and to reduce the adhesive force by cooling or heating during peeling to damage the semiconductor wafer. Semiconductors that can be peeled off without peeling, and that have almost no contaminants adhering to the semiconductor wafer surface from the pressure-sensitive adhesive layer after peeling, and that can respond to the increase in diameter and thickness of semiconductor wafers and the enhancement of IC performance. An object of the present invention is to provide an adhesive film for grinding a back surface of a wafer and a method of using the same.
[0009]
[Means for Solving the Problems]
The inventors of the present invention have conducted intensive studies and have found that a backside grinding of a semiconductor wafer in which a pressure-sensitive adhesive layer containing a crystalline polymer and having a property that the adhesive force changes dramatically with a change in temperature is formed on one side of a base film. Among the adhesive films for use, an adhesive film having a specific adhesive force characteristic can achieve the above-mentioned purpose, and can be used for grinding a back surface of a semiconductor wafer capable of responding to increase in diameter, thinning of a semiconductor wafer, and high performance of an IC. They have found that they can be used as an adhesive film, and have reached the present invention.
[0010]
Specifically, by including a crystalline polymer in the adhesive, the adhesive exhibits sufficient adhesive strength to protect the wafer surface only in a specific temperature range, and has an adhesive strength in a low temperature region or a high temperature region outside the temperature range. Was found to decrease, and furthermore, it was found that the above object could be achieved by performing sticking and polishing treatments in the above temperature range, and performing peeling treatment outside the temperature range, and reached the present invention.
[0011]
That is, the first invention of the present invention is an adhesive film for grinding a back surface of a semiconductor wafer in which an adhesive layer is provided on one surface of a base film, wherein the adhesive layer is formed of an adhesive containing a crystalline polymer. The adhesive force of the adhesive film for grinding the back surface of a semiconductor wafer is 150 to 2,000 g / 25 mm only in at least a part of the temperature range A to B ° C. (A <B) at a temperature of −10 ° C. or more, and An adhesive film for grinding a back surface of a semiconductor wafer, wherein the adhesive film has a weight of less than 150 g / 25 mm in a temperature range of less than A ° C.
[0012]
The second invention of the present invention is an adhesive film for grinding a semiconductor wafer back surface provided with an adhesive layer on one surface of a substrate film, wherein the adhesive layer is formed of an adhesive containing a crystalline polymer, The adhesive force of the adhesive film for grinding the back surface of a semiconductor wafer is 150 to 2,000 g / 25 mm only in at least a part of the temperature range E to F ° C. (E <F) at a temperature of 70 ° C. or less. An adhesive film for grinding a back surface of a semiconductor wafer, wherein the adhesive film has a weight of less than 150 g / 25 mm in a temperature range exceeding the temperature.
[0013]
A third invention of the present invention is a method of using an adhesive film for grinding a back surface of a semiconductor wafer, which is adhered to the surface of the semiconductor wafer when grinding the back surface and peeled off after finishing the grinding, wherein the adhesive film for grinding the back surface of the semiconductor wafer is One side of the base film has a pressure-sensitive adhesive layer formed of a pressure-sensitive adhesive containing a crystalline polymer, and has a pressure-sensitive adhesive strength of at least a part of the temperature range A to B ° C at a temperature of -10 ° C or more (A <B ) Only in the temperature range of 150 to 2,000 g / 25 mm, and in the temperature range of less than A ° C., less than 150 g / 25 mm, and at least a part of the temperature range C to D ° C. included in the temperature range of A to B ° C. ( A <C ≦ D <B, 1 ≦ C ≦ D ≦ 60), the pressure-sensitive adhesive film is adhered to the wafer surface, and the back surface of the semiconductor wafer is ground while applying cooling water in a temperature range of C to D ° C .; , Not A ℃ A method using the adhesive film for a semiconductor wafer back grinding, which comprises peeling the PSA film cooled state.
[0014]
Further, a fourth invention of the present invention is a method for using an adhesive film for grinding a back surface of a semiconductor wafer, which is adhered to the surface of the semiconductor wafer when grinding the back surface and peeled off after the grinding is completed. Has an adhesive layer formed of an adhesive containing a crystalline polymer on one surface of a substrate film, and has an adhesive strength of at least a part of a temperature range of 70 ° C. or lower at a temperature range of E to F ° C. (E <F F) only in 150 to 2,000 g / 25 mm, and in a temperature range exceeding F ° C., less than 150 g / 25 mm, and at least a part of the temperature range G to H ° C. included in the temperature range of E to F ° C. (E <G ≦ H <F, 1 ≦ G), the pressure-sensitive adhesive film is adhered to the wafer surface, and the back surface of the semiconductor wafer is ground while applying cooling water in a temperature range of G to H ° C .; Beyond A method using the adhesive film for a semiconductor wafer back grinding, characterized in that peeling off the PSA film while heating to a temperature.
[0015]
The adhesive film for grinding the back surface of a semiconductor wafer of the present invention (hereinafter referred to as an adhesive film) adheres to the wafer surface with a strong adhesive force when grinding the back surface of the semiconductor wafer to protect the wafer, and to prevent damage to the wafer. To prevent. Further, at the time of peeling, the adhesive strength can be reduced by cooling or heating, so that peeling can be facilitated and damage to the semiconductor wafer due to peeling stress can be prevented. Further, after the adhesive film is peeled off, contaminants caused by the adhesive layer hardly adhere to the wafer surface, and an excellent effect of preventing contamination of the wafer surface is exhibited. Therefore, according to the present invention, there is provided an adhesive film for grinding the back surface of a semiconductor wafer and a method for using the same, which can cope with an increase in diameter and thickness of a semiconductor wafer and an improvement in the performance of ICs.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
The pressure-sensitive adhesive film of the present invention is manufactured by applying a pressure-sensitive adhesive solution or an emulsion solution (hereinafter, referred to as a pressure-sensitive adhesive) containing a component constituting the pressure-sensitive adhesive layer to a base film and drying to form a pressure-sensitive adhesive layer. You. In this case, it is preferable to attach a release film to the surface of the pressure-sensitive adhesive layer in order to protect the pressure-sensitive adhesive layer from contamination caused by the environment. Also, a method of applying a pressure-sensitive adhesive on one surface of a release film and drying to form a pressure-sensitive adhesive layer, then attaching a base film to the surface of the pressure-sensitive adhesive layer and transferring the pressure-sensitive adhesive layer to the base film side It is also manufactured by In this case, there is an advantage that the surface of the pressure-sensitive adhesive layer is not contaminated when the pressure-sensitive adhesive layer is dried.
[0017]
Whether to apply the pressure-sensitive adhesive coating solution or the like to one surface of the base film or the release film is determined in consideration of heat resistance, surface tension, contamination on the semiconductor wafer surface, and the like of the base film and the release film. For example, when the heat resistance of the release film is superior to that of the base film, a pressure-sensitive adhesive layer is provided on the surface of the release film and then transferred to the base film. If the heat resistance is equal or the base film is better, a pressure-sensitive adhesive layer is provided on the surface of the base film, and a release film is attached to the surface. However, considering that the adhesive film is attached to the semiconductor wafer surface via the surface of the adhesive layer exposed when the release film is peeled off, in order to prevent contamination of the semiconductor wafer surface with the adhesive layer It is preferable to use a release film having good heat resistance, apply a pressure-sensitive adhesive coating solution to the surface of the release film, and dry the pressure-sensitive adhesive layer to form a pressure-sensitive adhesive layer.
[0018]
The method of using the pressure-sensitive adhesive film for backside grinding of a semiconductor wafer of the present invention is applied to a surface of a semiconductor wafer through a pressure-sensitive adhesive layer in a specific temperature range, protecting the wafer surface and grinding the backside of the wafer, It is a method in which the pressure-sensitive adhesive layer is cooled or heated outside the temperature range to make the temperature of the pressure-sensitive adhesive layer outside the temperature range, and then peeled off.
[0019]
First, the method for producing the pressure-sensitive adhesive film of the present invention will be described.
The pressure-sensitive adhesive film of the present invention is generally coated with a pressure-sensitive adhesive on one surface of a base film and dried to form a pressure-sensitive adhesive layer, or a pressure-sensitive adhesive is coated on one surface of a release film and dried. After forming a layer, it is manufactured by a method of transferring to one surface of a base film.
[0020]
As a method of applying the pressure-sensitive adhesive to one surface of the base film or the release film, conventionally known coating methods, for example, a roll coater method, a reverse roll coater method, a gravure roll coater method, a bar coater method, a comma coater method, a die coater Method can be adopted. In addition to the method of applying an adhesive, a method of co-extruding a base film and an adhesive layer is also included. These methods can be appropriately selected depending on the properties of the pressure-sensitive adhesive layer, the base film, and the like.
[0021]
Examples of the base film used for the pressure-sensitive adhesive film of the present invention include films manufactured from synthetic resin, natural rubber, synthetic rubber, and the like. If specifically exemplified, ethylene-vinyl acetate copolymer, ethylene-methacrylic acid copolymer, polybutadiene, soft vinyl chloride resin, polyolefin, polyester, polyamide, resins such as ionomers, and copolymer elastomers thereof, And films of a synthetic rubber such as a diene-based, nitrile-based, silicone-based, or acrylic-based rubber. The base film may be a single layer or a laminate.
[0022]
The thickness of the base film affects the prevention of breakage of the wafer when grinding the back surface of the semiconductor wafer, the workability of sticking to the wafer surface and the workability of peeling. From such a viewpoint, the thickness of the base film is usually 10 to 2000 μm. Preferably it is 100 to 300 μm. The thickness accuracy of the base film affects the thickness accuracy of the pressure-sensitive adhesive film, which in turn affects the thickness accuracy of the semiconductor wafer after the back surface grinding. Therefore, it is preferable that the base film is formed with an accuracy within ± 5 μm in the above thickness range. More preferably, it is within ± 3 μm.
[0023]
Considering the prevention of damage to the semiconductor wafer when the back surface is ground, the hardness of the base film is an elastic film formed by processing a resin having a Shore D-type hardness of 40 or less specified in ASTM-D-2240 into a film shape. For example, an ethylene-vinyl acetate copolymer film, a polybutadiene film and the like are preferably used. In this case, a film harder than the pressure-sensitive adhesive layer on the side opposite to the surface on which the pressure-sensitive adhesive layer is provided, specifically, a film formed by processing a resin having a Shore D-type hardness of more than 40 into a film is laminated. Is preferred. Thereby, the rigidity of the pressure-sensitive adhesive film is increased, and the sticking workability and the peeling workability are improved.
[0024]
Also, when the semiconductor wafer backside grinding adhesive film is applied to protect the surface of the semiconductor wafer by continuing the etching process using an acid that is performed after the backside of the semiconductor wafer is ground, it has excellent acid resistance. It is preferable to use a base film. An acid-resistant film may be laminated on the side of the base film opposite to the pressure-sensitive adhesive layer. Examples of the acid-resistant film include a polypropylene film.
In order to improve the adhesive strength between the substrate film and the pressure-sensitive adhesive layer, it is preferable to perform a corona discharge treatment or a chemical treatment on the surface of the substrate film on which the pressure-sensitive adhesive layer is provided. Further, an undercoating agent may be used between the base film and the pressure-sensitive adhesive layer.
[0025]
Examples of the release film provided on the surface of the pressure-sensitive adhesive of the pressure-sensitive adhesive film of the present invention include synthetic resin films such as polypropylene and polyethylene terephthalate. It is preferable that the surface thereof is subjected to a silicone treatment or the like as necessary. The thickness of the release film is usually 10 to 2000 μm. Preferably it is 30 to 100 μm.
[0026]
The pressure-sensitive adhesive layer provided on the pressure-sensitive adhesive film of the present invention is formed of a pressure-sensitive adhesive containing a crystalline polymer and exhibiting sufficient adhesive strength to protect the surface of the semiconductor wafer in a specific temperature range.
As a specific example of the pressure-sensitive adhesive, a pressure-sensitive adhesive described in, for example, Japanese Patent Publication No. 6-510548 (International Publication Number: WO92 / 13901) is preferable. That is, it is usually a mixture of a pressure-sensitive adhesive composition (hereinafter, referred to as a normal pressure-sensitive adhesive) used for a pressure-sensitive adhesive layer such as a pressure-sensitive adhesive tape, and a crystalline polymer. Usually, the mixing ratio is preferably such that the crystalline polymer is mixed in the range of about 0.3 to 50 parts by weight with respect to about 50 to 99.7 parts by weight of the usual adhesive. More preferably, the crystalline polymer is about 5-35 parts by weight with respect to about 65-95 parts by weight of the ordinary adhesive, and still more preferably, about 70-90 parts by weight of the ordinary adhesive. The amount of the crystalline polymer is about 10 to 30 parts by weight, and most preferably the amount of the crystalline polymer is about 20 to about 30 parts by weight based on about 70 to 80 parts by weight of a usual adhesive.
[0027]
Examples of ordinary pressure-sensitive adhesives include natural rubber-based pressure-sensitive adhesives, styrene-butadiene copolymer-based pressure-sensitive adhesives, and acrylic-based such as polyacrylate alkyl esters having an alkyl group having 1 to 9 carbon atoms or copolymers thereof. Examples thereof include synthetic rubber-based pressure-sensitive adhesives such as pressure-sensitive adhesives, and these may be used alone or as a mixture of two or more.
[0028]
These ordinary pressure-sensitive adhesives preferably have a functional group that can serve as a cross-linking point when it is necessary to adjust the cohesive strength and the adhesive force characteristics using a cross-linking agent. Examples of the functional group include a carboxyl group, a hydroxyl group, and an amino group. Further, a plasticizer, a tackifier, a stabilizer and the like may be appropriately mixed with these ordinary pressure-sensitive adhesives.
[0029]
Examples of the crystalline polymer include a side-chain crystalline polymer and a main-chain crystalline polymer. The former is preferred in consideration of the dependency of the adhesive force on the temperature change. As the side chain crystalline polymer, a monomer having one or more monomers having a polymerizable carbon-carbon double bond and having a side chain capable of being crystallized when polymerized (hereinafter, referred to as a monomer). A polymer or copolymer obtained by polymerizing SCC monomer) and a copolymer or copolymer obtained by copolymerizing SCC monomer and another monomer copolymerizable with SCC monomer. Polymers. The SCC monomers may be used alone or as a mixture of two or more. Further, other monomers copolymerizable with the SCC monomer may be used as a mixture of two or more kinds.
[0030]
As these SCC monomers, acrylates, methacrylates, acrylamide derivatives, methacrylamide derivatives, vinyl ether derivatives, vinyl ester derivatives having at least 10 to 50 carbon atoms and having an aliphatic group, 6 to 50 carbon atoms at least partially fluorine-substituted. At least one monomer selected from acrylates, methacrylates, acrylamide derivatives, methacrylamide derivatives, vinyl ether derivatives, vinyl ester derivatives, and styrene derivatives having an alkyl group having 8 to 24 carbon atoms having an aliphatic group of Is mentioned.
[0031]
Among these, acrylates, methacrylates, acrylamide derivatives, methacrylamide derivatives and the like having a linear aliphatic group having 14 to 50 carbon atoms are preferable in consideration of the temperature dependence of the adhesive property, the polymerization reactivity and the like. More preferred are acrylates, methacrylates, acrylamide derivatives, methacrylamide derivatives and the like having a linear aliphatic group having 14 to 22 carbon atoms.
Other monomers copolymerizable with the SCC monomer include alkyl acrylates or alkyl methacrylates having an alkyl group having 1 to 9 carbon atoms, vinyl acetate, acrylonitrile, styrene and the like. .
[0032]
Considering the necessity of adjusting the cohesive force or adhesive force characteristics using a cross-linking agent, it is preferable to copolymerize a monomer having a functional group that can be a cross-linking point in the side-chain crystalline polymer. . Monomers having a functional group that can be a crosslinking point include acrylic acid, methacrylic acid, itaconic acid, mesaconic acid, citraconic acid, fumaric acid, maleic acid, itaconic acid monoalkyl ester, mesaconic acid monoalkyl ester, citraconic acid monoalkyl ester Esters, monoalkyl fumarate, monoalkyl maleate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, acrylamide, methacrylamide, tert-butylaminoethyl acrylate, tert-butylaminoethyl methacrylate and the like. .
[0033]
Monomers having a self-crosslinkable functional group such as glycidyl acrylate, glycidyl methacrylate, isocyanate ethyl acrylate, isocyanate ethyl methacrylate, 2- (1-aziridinyl) ethyl acrylate, and 2- (1-aziridinyl) ethyl methacrylate Further, polyfunctional monomers such as divinylbenzene, vinyl acrylate, vinyl methacrylate, allyl acrylate, and allyl methacrylate may be combined.
[0034]
In consideration of the adhesive force characteristics of the adhesive film, the side chain crystalline polymer is preferably synthesized such that the total mass of the crystalline side chains is 50% by weight or more of the total mass of the crystalline polymer. It is more preferably at least 65% by weight.
[0035]
As a method for polymerizing the side chain crystalline polymer, various known methods such as a solution polymerization method, a suspension polymerization method, and an emulsion polymerization method can be adopted. Examples of the polymerization reaction mechanism include radical polymerization, anionic polymerization, and cationic polymerization, and it is preferable to perform polymerization by radical polymerization in consideration of the production cost of the pressure-sensitive adhesive. When polymerizing by a radical polymerization reaction, organic radicals such as benzoyl peroxide, acetyl peroxide, isobutyryl peroxide, octanoyl peroxide, di-tert-butyl peroxide, di-tert-amyl peroxide are used as radical polymerization initiators. Inorganic peroxides such as peroxides, ammonium persulfate, potassium persulfate, and sodium persulfate, 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, 4,4 And azo compounds such as' -azobis-4-cyanovaleric acid. These are appropriately selected depending on the properties of the obtained side-chain crystalline polymer and the polymerization method.
[0036]
As the side-chain crystalline polymer, in addition to the above-mentioned polymers, polyester-based, polyether-based, polyamide-based, polyethyleneimine-based, and silicone-based polymers and the like may be used as long as they have a crystalline side chain. Can be
Examples of the main chain crystalline polymer include water-insoluble polyalkylene oxide, lower alkyl polyester, polyamide, nylon, polytetrahydrofuran, and a compound represented by the general formula (1):
[0037]
Embedded image
[0038]
Considering the temperature dependence of the adhesive property and the contamination of the semiconductor wafer surface, the crystalline polymer preferably has a molecular weight of about 3,500 to 900,000. The molecular weight of these crystalline polymers particularly affects the temperature dependence of the adhesive properties, and depending on the molecular weight, a temperature range that shows sufficient adhesive strength to protect the wafer surface when attached to the wafer surface ( Hereinafter, this temperature range will be referred to as a temperature range of A to B ° C. or a temperature range of E to F ° C.). For example, as the molecular weight of the crystalline polymer increases, the value of the upper limit B or F of the temperature range tends to increase. In particular, in the case of the second and fourth inventions, if the molecular weight is too high, the pressure-sensitive adhesive layer The adhesive film can be heated even if it is heated to a temperature that causes chemical interaction between the wafer and the wafer surface (corrosion, contamination, etc. of the wafer surface), the decomposition temperature of the adhesive layer, the softening temperature of the base film, etc. It may not be possible to peel off. Therefore, the molecular weight of the crystalline polymer needs to be determined in consideration of the temperature conditions (temperature of cooling water, temperature at the time of peeling, etc.) in the back surface grinding step of the semiconductor wafer, contamination on the wafer surface, and the like.
[0039]
For example, when a pressure-sensitive adhesive film formed with a pressure-sensitive adhesive exhibiting sufficient adhesive strength to protect the surface of a wafer only in a temperature range of E to F ° C. is peeled off by heating outside the temperature range of F ° C., the molecular weight is It is preferable to adjust to a range of about 3,500 to 25,000, and more preferably to a range of about 3,500 to 12,000.
[0040]
Further, when the pressure-sensitive adhesive film on which the pressure-sensitive adhesive exhibiting sufficient adhesive strength to protect the surface of the wafer only in the temperature range of A to B ° C. is peeled off by cooling outside the temperature range of A ° C., Although there is no particular problem with the molecular weight of the compound, a higher molecular weight is preferable in consideration of the contamination on the wafer surface. Therefore, the molecular weight is preferably adjusted to a range of about 25,000 to 900,000, and more preferably 100,000. It is in the range of about 900,000.
[0041]
The mixture of the ordinary pressure-sensitive adhesive and the crystalline polymer may be cross-linked as necessary in consideration of the adhesive force characteristics, adjustment of cohesion, contamination on the wafer surface, and the like. Although it depends on the state of the unevenness of the wafer, when the adhesive film is peeled off after cooling after grinding the back surface of the wafer, the adhesive force tends to be reduced more easily by crosslinking. The cross-linking method can be appropriately selected from known cross-linking methods such as cross-linking with a cross-linking agent and cross-linking with light or radiation. Cross-linking with a cross-linking agent is preferable in view of the simplicity of the cross-linking method.
[0042]
Examples of the crosslinking agent include tetramethylene diisocyanate, hexamethylene diisocyanate, toluene diisocyanate triadduct of trimethylolpropane, isocyanate compounds such as polyisocyanate, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, and diglycerol. Epoxy compounds such as polyglycidyl ether, glycerol polyglycidyl ether, neopentyl glycol diglycidyl ether, resorcin diglycidyl ether, trimethylolpropane-tri-β-aziridinylpropionate, tetramethylolmethane-tri-β- Aziridinyl propionate, N, N'-diphenylmethane-4,4'-bis (1-aziridinecarboxyamido ), N, N'-hexamethylene-1,6-bis (1-aziridinecarboxamide), N, N'-toluene-2,4-bis (1-aziridinecarboxamide), trimethylolpropane-tri-β Aziridine compounds such as-(2-methylaziridine) propionate; melamine compounds such as hexamethoxymethylolmelamine; These may be used alone or in combination of two or more.
[0043]
The amount of the cross-linking agent varies depending on the adhesive properties required for the adhesive layer, the cohesive strength, the properties of the ordinary adhesive and the crystalline polymer, and the like, but is usually 100% by weight of the mixture of the ordinary adhesive and the crystalline polymer. The amount is appropriately selected within the range of 0.01 to 30 parts by weight based on parts.
[0044]
The thickness of the pressure-sensitive adhesive layer is appropriately determined according to the surface condition, shape, and back surface grinding method of the semiconductor wafer. However, the adhesive force when the back surface of the semiconductor wafer is ground, the releasability after the grinding is completed, and the like. In consideration of this, it is usually about 2 to 100 μm. Preferably it is 5-70 μm.
[0045]
The pressure-sensitive adhesive film of the present invention obtained as described above is a wafer from the step of sticking the pressure-sensitive adhesive film on the surface of the semiconductor wafer to the step immediately before the step of peeling the pressure-sensitive adhesive film through the step of grinding the back surface of the wafer. It is an adhesive film that has sufficient adhesive strength to adhere firmly to the surface and protect the wafer surface. Here, the adhesive force sufficient to protect the wafer surface is an adhesive force that does not cause peeling during polishing of the back surface of the wafer or intrusion of cooling water between the wafer surface and the adhesive layer. Specifically, in accordance with the method specified in JIS Z 0237, a SUS304-BA plate is used as an adherend, and a peeling speed of 300 mm / min. The adhesive force measured under the condition of a peel angle of 180 degrees usually falls within a range of 150 to 2000 g / 25 mm at a predetermined temperature. Preferably it is in the range of 200 to 2000 g / 25 mm.
[0046]
Thus, the pressure-sensitive adhesive film according to the present invention produced as described above has a thickness of 150 to 2,000 g / 25 mm only in at least a part of the temperature range A to B ° C (A <B) at a temperature of -10 ° C or higher. By exhibiting an adhesive force and cooling to a temperature region lower than A ° C., the adhesive force is reduced to less than 150 g / 25 mm. Preferred adhesive strength in the temperature range A to B ° C (A <B) is 200 to 2000 g / 25 mm. The preferred adhesive strength in the temperature range below A ° C. is 80 g / 25 mm or less. Further, the preferable temperature range of A to B ° C. is at least a part of the temperature range of 10 ° C. or more. Here, the upper limit temperature in the “temperature range of −10 ° C. or more” is not particularly limited, but the base film is substantially softened by heating, and the measurement of the adhesive strength defined in the present invention is practically impossible. Specifically, the temperature of the softening temperature of the raw material resin of the base film (that is, the resin before film formation) measured in accordance with JIS K 2207 (ring and ball method) + about 50 ° C. No. When the base film has a melting point, the temperature around the melting point is the upper limit temperature.
[0047]
In addition, the pressure-sensitive adhesive film according to another invention of the present invention exhibits a pressure-sensitive adhesive strength of 150 to 2,000 g / 25 mm only in at least a part of the temperature range E to F ° C (E <F) at a temperature of 70 ° C or less, Further, by heating to a temperature region exceeding F ° C., the adhesive strength is reduced to less than 150 g / 25 mm. Preferably, the temperature range of E to F ° C is at least a part of the temperature range at a temperature of 60 ° C or less. The preferred adhesive strength in the temperature range E to F ° C (E <F) is 200 to 2000 g / 25 mm. The preferred adhesive strength in a temperature range exceeding F ° C. is 80 g / 25 mm or less. Here, the lower limit temperature in the “temperature range of 70 ° C. or less” is not particularly limited, but substantially, the base film becomes brittle upon cooling, and the adhesive strength defined in the present invention. Is the temperature at which the measurement of is virtually impossible. Specifically, the temperature is about -100 ° C., which is the brittleness temperature of the raw material resin of the base film (that is, the resin before being formed into a film) measured in accordance with ASTM D-746.
[0048]
Further, in consideration of the actual workability, it is preferable that any of the above-mentioned pressure-sensitive adhesive films exhibit a sufficient adhesive force to protect the wafer surface within a temperature range of at least 20 to 25 ° C. More preferably, it has sufficient adhesive strength to protect the wafer surface in a temperature range of at least 15 to 30 ° C.
[0049]
Next, a method for using the adhesive film for grinding the back surface of a semiconductor wafer of the present invention will be described. As a first method, the release film is peeled from the pressure-sensitive adhesive layer of the pressure-sensitive adhesive film to expose the surface of the pressure-sensitive adhesive layer, and the surface of the semiconductor wafer on which the integrated circuit is formed is -10 through the pressure-sensitive adhesive layer. At least a part of the temperature range C to D ° C (A <C ≦ D <B, 1 ≦ C ≦ D) included in at least a part of the temperature range A to B ° C (A <B) at a temperature of not less than ° C. ≦ 60), an adhesive film is adhered to the wafer surface, the semiconductor wafer is fixed to a chuck table or the like of a grinding machine via the base film side of the adhesive film, and cooling water in a temperature range of C to D ° C. is applied. A method of grinding the back surface of the semiconductor wafer and then peeling the adhesive film in a state where the pressure-sensitive adhesive film is cooled to a temperature lower than A ° C. is exemplified.
[0050]
It is preferable that the temperature range of C to D ° C., which is a temperature of the cooling water, in which an adhesive film is stuck on the wafer surface, is 10 ≦ C ≦ D ≦ 40. In order to control the temperature in a temperature range showing sufficient adhesive strength to protect the surface of the semiconductor wafer, it is necessary to control the temperature of the cooling water during the grinding, the room temperature of the grinding, and the like within the range of C to D ° C. The peeling temperature may be any temperature as long as it is lower than A ° C, but is preferably -30 ° C or higher in consideration of actual workability.
[0051]
Further, as a second method, the release film is peeled from the pressure-sensitive adhesive layer of the pressure-sensitive adhesive film to expose the surface of the pressure-sensitive adhesive layer, and the surface of the semiconductor wafer on which the integrated circuit is formed through the pressure-sensitive adhesive layer, The adhesive film is adhered to the wafer surface in at least a part of the temperature range G to H ° C (E <G ≦ H <F, 1 ≦ G) included in the temperature of 70 ° C. or less, and the base film side of the adhesive film The semiconductor wafer is fixed to a chuck table or the like of a grinding machine through the above, the back surface of the semiconductor wafer is ground while applying cooling water in a temperature range of G to H ° C, and then heated to a temperature exceeding F ° C. A method of peeling the adhesive film can be used.
[0052]
It is preferable that the temperature range of G to H ° C., which is the temperature of the cooling water, in which an adhesive film is stuck on the wafer surface, is 10 ≦ G ≦ H ≦ 40. In order to control the temperature in a temperature range showing sufficient adhesive strength to protect the surface of the semiconductor wafer, it is necessary to control the temperature of the cooling water during the grinding, the room temperature of the grinding, and the like within the range of G to H ° C. The peeling temperature may be any temperature as long as it exceeds F ° C., but usually, the temperature at which a chemical interaction (corrosion, contamination, etc. of the wafer surface) occurs between the pressure-sensitive adhesive layer and the wafer surface, the pressure-sensitive adhesive layer It is preferable that the temperature does not exceed any of the temperature at which a part of the base film starts to decompose or the softening temperature of the base film. Specifically, when the softening temperature of the base film is 100 ° C or lower, the base film is peeled at a temperature lower than the softening temperature, and when the softening temperature of the base film exceeds 100 ° C, the base film is peeled at a temperature of 100 ° C or lower. Is preferred.
[0053]
The adhesive strength of the adhesive film of the present invention can be appropriately adjusted within the above range in consideration of various factors such as the diameter of the semiconductor wafer to be ground, the grinding time, the surface shape of the semiconductor wafer, and the thickness after grinding.
There is no particular limitation on a device, a tool, and the like for grinding the back surface of the semiconductor wafer, and a known method can be applied. After the grinding of the back surface of the semiconductor wafer is completed, a chemical etching step may be performed before the adhesive film is peeled off (in this case, the chemical etching layer needs to be controlled within the range of A to B ° C. or E to F ° C.). It is preferably C to D ° C or G to H ° C.
Semiconductor wafers to which the present invention can be applied include not only silicon wafers but also wafers made of germanium, gallium-arsenic, gallium-phosphorus, gallium-arsenic-aluminum, and the like.
[0054]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples.
In the following Examples and Comparative Examples, the production of the adhesive film for grinding the back surface of the semiconductor wafer (after the preparation of the adhesive coating solution) and the grinding of the back surface of the semiconductor wafer using the adhesive film for grinding the back surface of the semiconductor wafer are all U.S.A. The test was performed in an environment in which the cleanliness of class 1,000 or less specified by the standard 209b was maintained.
The present invention is not limited to these examples.
In addition, the synthesis | combination of the normal adhesive (acrylic adhesive) and the crystalline polymer (side-chain crystalline polymer) used in this Example was performed according to the method of the following preparation examples 1-4. In addition, the performance of the obtained pressure-sensitive adhesive film and each characteristic in a method of grinding a back surface of a semiconductor wafer using the film were evaluated by the following methods (1) to (3).
[0055]
(1) Number of damaged semiconductor silicon wafers during back grinding (number)
The adhesive film obtained in each of the examples and comparative examples was attached to the surface of a semiconductor silicon wafer (diameter: 8 inches, thickness: 600 μm, surface irregularities: about 10 μm) on which an integrated circuit was formed, and a grinder [ Using a back grinder DFG-821F / 8, manufactured by Disco Co., Ltd., the back surface of the semiconductor silicon wafer is ground while cooling with water of a predetermined water temperature until the thickness of the wafer becomes 200 μm. After the grinding, the film is peeled off under a predetermined condition. Twenty semiconductor silicon wafers were used for each Example and Comparative Example, and the grinding was performed 20 times. The number of wafers damaged during back surface grinding (due to peeling of the adhesive film during grinding), The number of wafers in which water entered between them and the number of wafers damaged during peeling are counted.
[0056]
(2) Observation of contamination on semiconductor wafer by microscope (%)
For the wafer that was not damaged during the grinding of the back side of the semiconductor wafer and the peeling of the adhesive film in the above (1), the integrated circuit on the wafer surface was subjected to 50 to 1000 using an optical microscope (Nikon Corp .: OPTIPHOT2). Observe the entire wafer surface and even microscopic parts of the circuit in a range of 2 × to evaluate the percentage of contaminated chips.
[0057]
(3) Adhesive force (g / 25mm) characteristics
The basic operation is performed under the following conditions in accordance with the method described in JIS Z 0237.
The pressure-sensitive adhesive films obtained in Examples and Comparative Examples are adhered to the surface of a SUS304-BA plate (length: 20 cm, width: 5 cm) via the pressure-sensitive adhesive layer, and left at 23 ° C. for 30 minutes. After standing, one end of the sample was clamped, and the peeling angle: 180 °, peeling speed: 300 mm / min. At a predetermined temperature, the sample is peeled from the surface of the SUS304-BA plate, and the stress at the time of peeling is measured and converted to g / 25 mm.
[0058]
Preparation Example 1
<Synthesis of acrylic pressure-sensitive adhesive (hereinafter, polymer 1)>
91 parts by weight of butyl acrylate, 4.5 parts by weight of acrylonitrile, and 4.5 parts by weight of acrylic acid in 150 parts by weight of toluene, and 2,2′-azobis-isobutyronitrile (hereinafter referred to as AIBN) 1 as an initiator The copolymer was copolymerized at 80 ° C. under a nitrogen atmosphere using parts by weight to obtain a polymer 1 solution (solid content: 40% by weight).
[0059]
Preparation Example 2
<Synthesis of Side Chain Crystalline Polymer 1 (hereinafter, polymer 2)>
98 parts by weight of hexadecyl methacrylate and 2 parts by weight of acrylic acid were copolymerized in 180 parts by weight of toluene in the presence of 5 parts by weight of dodecyl mercaptan and 1 part by weight of AIBN at 80 ° C. under a nitrogen atmosphere using 1 part by weight of AIBN. A solution of molecule 2 (solid content 36% by weight) was obtained.
[0060]
Preparation Example 3
<Synthesis of Side-Chain Crystalline Polymer 2 (hereinafter, polymer 3)>
98 parts by weight of octadecyl acrylate and 2 parts by weight of acrylic acid were copolymerized in 180 parts by weight of toluene in the presence of 5 parts by weight of dodecyl mercaptan and 1 part by weight of AIBN at 80 ° C. under a nitrogen atmosphere using 1 part by weight of AIBN. A solution of molecule 3 (solid content 36% by weight) was obtained.
[0061]
Preparation Example 4
<Synthesis of Side-Chain Crystalline Polymer No. 3 (hereinafter, polymer 4)>
98 parts by weight of hexadecyl methacrylate and 2 parts by weight of acrylic acid were copolymerized in 180 parts by weight of ethyl acetate at 75 ° C. in a nitrogen atmosphere using 0.2 parts by weight of AIBN as an initiator to obtain a solution of polymer 4 (solid 36% by weight).
[0062]
Example 1
75 parts by weight of the polymer 1 solution (solid content 40% by weight) synthesized in Preparation Example 1 and 25 parts by weight of the polymer 2 solution (solid content 36% by weight) synthesized in Preparation Example 2 were mixed. And 1 part by weight of an isocyanate-based crosslinking agent (Olester P49-60SX, manufactured by Mitsui Toatsu Chemicals, Inc., solid content: 60% by weight) was added to obtain a pressure-sensitive adhesive coating solution. This pressure-sensitive adhesive coating solution was applied to one surface of a polypropylene film (release film, thickness: 50 μm) using a roll coater, and dried at 120 ° C. for 1 minute to provide a pressure-sensitive adhesive layer having a thickness of 15 μm. Then, the treated surface of an ethylene-vinyl acetate copolymer film (Shore D type hardness: 38) having a thickness of 120 μm that has been subjected to corona discharge treatment is bonded and pressed to transfer the pressure-sensitive adhesive layer, whereby the pressure-sensitive adhesive layer is transferred. Manufactured.
[0063]
In an environment where the room temperature was controlled at 23 ° C., the release film was peeled from the pressure-sensitive adhesive layer of the obtained pressure-sensitive adhesive film, the surface of the pressure-sensitive adhesive layer was exposed, and an integrated circuit was formed through the pressure-sensitive adhesive layer. Affixed to the surface of a semiconductor silicon wafer (diameter: 8 inches, thickness: 600 μm, difference in surface irregularities: about 10 μm), and the temperature was adjusted to 23 ° C. using a grinding machine (manufactured by Disco Corporation: Back Grinder DFG-821F / 8). While cooling with water, the back surface of the semiconductor silicon wafer was ground until the thickness of the wafer became 200 μm. After grinding, the wafer was cooled to 5 ° C. with the film adhered, and the film was peeled off while maintaining the temperature. The same operation was performed 20 times on 20 semiconductor wafers. None of the wafers was damaged during grinding, water invaded between the wafer and the adhesive film, or damaged during peeling. Table 1 shows the adhesive properties of the obtained adhesive film under the conditions used in Example 1, the contamination on the semiconductor wafer surface, and the grinding results.
[0064]
Example 2
A semiconductor on which an integrated circuit was formed in the same manner as in Example 1 except that the temperature of the cooling water was set to 30 ° C. in the same environment as in Example 1 using the adhesive film obtained in Example 1. The back surface of the silicon wafer (same as in Example 1) was ground until the thickness of the wafer became 200 μm. After the grinding, the wafer was cooled to 10 ° C. with the film adhered, and the film was peeled off while maintaining the temperature. The same operation was performed 20 times on 20 semiconductor wafers. None of the wafers was damaged during grinding, water invaded between the wafer and the adhesive film, or damaged during peeling. The adhesive properties of the pressure-sensitive adhesive film of Example 1 under the conditions used in Example 2, the contamination on the semiconductor wafer surface, and the grinding results are shown in [Table 1].
[0065]
Example 3
75 parts by weight of the polymer 1 solution (solid content 40% by weight) synthesized in Preparation Example 1 and 25 parts by weight of the polymer 3 solution (solid content 36% by weight) synthesized in Preparation Example 3 were mixed. And 2 parts by weight of an isocyanate-based crosslinking agent (Olester P49-60SX, manufactured by Mitsui Toatsu Chemicals, Inc., solid content: 60% by weight) were added to obtain an adhesive coating solution. Using this adhesive coating solution, an adhesive film was produced in the same manner as in Example 1.
[0066]
Using the obtained adhesive film, in the same environment as in Example 1, the thickness of the back surface of the semiconductor silicon wafer on which the integrated circuit was formed (same as in Example 1) was obtained in the same manner as in Example 1. Grinding was performed to 200 μm. After the grinding was completed, the wafer was heated to 65 ° C. with the film adhered, and the film was peeled off while maintaining the temperature. The same operation was performed 20 times on 20 semiconductor wafers. None of the wafers was damaged during grinding, water invaded between the wafer and the adhesive film, or damaged during peeling. The adhesive properties of the obtained adhesive film under the conditions used in Example 3, the contamination on the semiconductor wafer surface, and the grinding results are shown in [Table 1].
[0067]
Example 4
Using the pressure-sensitive adhesive film obtained in Example 3, a semiconductor having an integrated circuit formed in the same manner as in Example 1 except that the temperature of the cooling water was set to 40 ° C. in the same environment as in Example 1. The back surface of the silicon wafer (same as in Example 1) was ground until the thickness of the wafer became 200 μm. After the grinding was completed, the wafer was heated to 55 ° C. with the film adhered, and the film was peeled off while maintaining the temperature. The same operation was performed 20 times on 20 semiconductor wafers. None of the wafers was damaged during grinding, water invaded between the wafer and the adhesive film, or damaged during peeling. The adhesive properties of the adhesive film of Example 3 under the conditions used in Example 4, the contamination on the semiconductor wafer surface, and the grinding results are shown in [Table 1].
[0068]
Example 5
70 parts by weight of the polymer 1 solution (solid content 40% by weight) synthesized in Preparation Example 1 and 30 parts by weight of the polymer 4 solution (solid content 36% by weight) synthesized in Preparation Example 4 were mixed. And 1.5 parts by weight of an isocyanate-based crosslinking agent (Olester P49-60SX, manufactured by Mitsui Toatsu Chemicals, Inc., solid content: 60% by weight) were added to obtain a pressure-sensitive adhesive coating solution. Using this adhesive coating solution, an adhesive film was produced in the same manner as in Example 1.
[0069]
Using the obtained adhesive film, in the same environment as in Example 1, in the same manner as in Example 1, the back surface of the semiconductor silicon wafer on which the integrated circuit was formed (same as in Example 1) was thinned. Was ground to 200 μm. After the grinding, the film was peeled off in the same manner as in Example 1. The same operation was performed 20 times on 20 semiconductor wafers. None of the wafers was damaged during grinding, water invaded between the wafer and the adhesive film, or damaged during peeling. The adhesive properties of the obtained adhesive film under the conditions used in Example 5, the contamination on the semiconductor wafer surface, and the grinding results are shown in [Table 1].
[0070]
Example 6
Using the pressure-sensitive adhesive film obtained in Example 5, a semiconductor having an integrated circuit formed in the same manner as in Example 1 except that the temperature of the cooling water was set to 40 ° C. under the same environment as in Example 1. The back surface of the silicon wafer (same as in Example 1) was ground until the thickness of the wafer became 200 μm. After the grinding, the film was peeled off in the same manner as in Example 2. The same operation was performed 20 times on 20 semiconductor wafers. None of the wafers was damaged during grinding, water invaded between the wafer and the adhesive film, or damaged during peeling. The adhesive properties of the pressure-sensitive adhesive film of Example 5 under the conditions used in Example 6, the contamination on the semiconductor wafer surface, and the grinding results are shown in [Table 1].
[0071]
[Table 1]
Comparative Example 1
Using the pressure-sensitive adhesive film obtained in Example 1, the back surface of a semiconductor silicon wafer on which an integrated circuit is formed (same as in Example 1) in the same environment as in Example 1 in the same environment as in Example 1. Was ground until the thickness of the wafer became 200 μm. After the completion of the grinding, the film was peeled off without cooling. The same operation was performed 20 times on 20 semiconductor wafers. None of the wafers damaged during grinding and water invaded between the wafer and the adhesive film, but 11 wafers were damaged during peeling. The adhesive properties of the adhesive film of Example 1 under the conditions used in Comparative Example 1, the contamination on the semiconductor wafer surface, and the grinding results are shown in Table 2.
[0073]
Comparative Example 2
Using the pressure-sensitive adhesive film obtained in Example 3, under the same environment as in Example 1, in the same manner as in Example 1, the back surface of a semiconductor silicon wafer on which an integrated circuit is formed (same as in Example 1) Was ground until the thickness of the wafer became 200 μm. After the grinding, the film was peeled off without heating. The same operation was performed 20 times on 20 semiconductor wafers. None of the wafers damaged during grinding and water invaded between the wafer and the adhesive film, but four wafers were damaged during peeling. The adhesive properties of the adhesive film of Example 3 under the conditions used in Comparative Example 2, the contamination on the semiconductor wafer surface, and the grinding results are shown in [Table 2].
[0074]
Comparative Example 3
Using the pressure-sensitive adhesive film obtained in Example 5, under the same environment as in Example 1, in the same manner as in Example 1, the back surface of a semiconductor silicon wafer on which an integrated circuit is formed (same as in Example 1) Was ground until the thickness of the wafer became 200 μm. After the completion of the grinding, the film was peeled off without cooling. The same operation was performed 20 times on 20 semiconductor wafers. None of the wafers damaged during grinding and water invaded between the wafer and the adhesive film, but ten wafers were damaged during peeling. [Table 2] shows the adhesive properties of the pressure-sensitive adhesive film of Example 5 under the use conditions of Comparative Example 3, the contamination on the semiconductor wafer surface, and the grinding results.
[0075]
Comparative Example 4
In a 5 ° C. environment, the pressure-sensitive adhesive film obtained in Example 1 was adhered to the surface of a semiconductor silicon wafer on which an integrated circuit was formed (same as in Example 1) via the pressure-sensitive adhesive layer. There was little power and it could not be applied. The results are shown in [Table 2].
[0076]
Comparative Example 5
The pressure-sensitive adhesive film obtained in Example 3 was heated to 65 ° C., and was stuck to the surface of a semiconductor silicon wafer on which an integrated circuit was formed (the same as in Example 1) at the same temperature via the pressure-sensitive adhesive layer. However, the film immediately began to rise from the periphery of the semiconductor wafer, and the back surface of the wafer became impossible to grind. The results are shown in [Table 2].
[0077]
Comparative Example 6
In a 5 ° C. environment, the pressure-sensitive adhesive film obtained in Example 5 was adhered to the surface of a semiconductor silicon wafer on which an integrated circuit was formed (same as in Example 1) via the pressure-sensitive adhesive layer. There was little power and it could not be applied. The results are shown in [Table 2].
[0078]
Comparative Example 7
Using the pressure-sensitive adhesive film obtained in Example 1, a semiconductor in which an integrated circuit was formed in the same manner as in Example 1 under the same environment as in Example 1 except that the temperature of the cooling water was 10 ° C. The back surface of the silicon wafer (same as in Example 1) was ground until the thickness of the wafer became 200 μm. After grinding, the wafer was maintained at 10 ° C. with the film adhered, and the film was peeled off while maintaining the temperature. The same operation was performed 20 times on 20 semiconductor wafers. Ten wafers were damaged during the grinding, and water intrusion was observed between the wafer and the adhesive film in all the remaining wafers (10 wafers) that were not damaged. There was no breakage of the wafer when the tape was peeled from the wafer in which water intrusion was recognized. [Table 2] shows the adhesive properties of the pressure-sensitive adhesive film of Example 1 under the use conditions of Comparative Example 7, the contamination on the semiconductor wafer surface, and the grinding results.
[0079]
Comparative Example 8
A semiconductor on which an integrated circuit was formed in the same manner as in Example 1 except that the temperature of the cooling water was set to 55 ° C. in the same environment as in Example 1 using the adhesive film obtained in Example 3. The back surface of the silicon wafer (same as in Example 1) was ground until the thickness of the wafer became 200 μm. After the grinding was completed, the wafer was maintained at 55 ° C. with the film adhered, and the film was peeled off while maintaining the temperature. The same operation was performed 20 times on 20 semiconductor wafers. Eleven wafers were damaged during the grinding, and water intrusion was observed between the wafer and the adhesive film in all the remaining undamaged wafers (nine). There was no breakage of the wafer when the tape was peeled from the wafer in which water intrusion was recognized. The adhesive properties of the adhesive film of Example 3 under the conditions used in Comparative Example 8, the contamination on the semiconductor wafer surface, and the grinding results are shown in Table 2.
[0080]
Comparative Example 9
Using the pressure-sensitive adhesive film obtained in Example 5, a semiconductor having an integrated circuit formed in the same manner as in Example 1 except that the temperature of the cooling water was set to 10 ° C. in the same environment as in Example 1. The back surface of the silicon wafer (same as in Example 1) was ground until the thickness of the wafer became 200 μm. After grinding, the wafer was maintained at 10 ° C. with the film adhered, and the film was peeled off while maintaining the temperature. The same operation was performed 20 times on 20 semiconductor wafers. Ten wafers were damaged during the grinding, and water intrusion was observed between the wafer and the adhesive film in all the remaining wafers (10 wafers) that were not damaged. There was no breakage of the wafer when the tape was peeled from the wafer in which water intrusion was recognized. The adhesive properties of the adhesive film of Example 5 under the conditions used in Comparative Example 9, the contamination to the semiconductor wafer surface, and the grinding results are shown in [Table 2].
[0081]
[Table 2]
Comparative Example 10
100 parts by weight of the solution of polymer 1 (solid content 40% by weight) synthesized in Preparation Example 1 was mixed with an isocyanate-based crosslinking agent (Olester P49-60SX, manufactured by Mitsui Toatsu Chemicals, Inc., solid content 60%) 1.2. A part by weight was added to obtain an adhesive coating solution. This pressure-sensitive adhesive coating solution was applied to a polypropylene film (release film, thickness: 50 μm) using a roll coater, and dried at 120 ° C. for 1 minute to provide a 15 μm-thick pressure-sensitive adhesive layer. Then, the treated surface of an ethylene-vinyl acetate copolymer film (Shore D type hardness: 38) having a thickness of 120 μm that has been subjected to corona discharge treatment is bonded and pressed to transfer the pressure-sensitive adhesive layer, whereby the pressure-sensitive adhesive layer is transferred. Manufactured.
[0083]
In the same environment as in Example 1, the back surface of the semiconductor silicon wafer on which the integrated circuit was formed (same as in Example 1) was ground by the same method as in Example 1 until the wafer thickness became 200 μm. After grinding, the wafer was cooled to 5 ° C. with the film adhered, and the film was peeled off while maintaining the temperature. The same operation was performed 20 times on 20 semiconductor wafers. None of the wafers damaged during grinding and water invaded between the wafer and the adhesive film, but thirteen wafers were damaged during peeling. [Table 3] shows the adhesive properties of the obtained adhesive film under the use conditions of Comparative Example 10, the contamination to the semiconductor wafer surface, and the grinding results.
[0084]
Comparative Example 11
Using the pressure-sensitive adhesive film obtained in Comparative Example 10, in the same environment as in Example 1, in the same manner as in Example 1, the back surface of a semiconductor silicon wafer on which an integrated circuit is formed (same as in Example 1) Was ground until the thickness of the wafer became 200 μm. After the grinding was completed, the wafer was heated to 65 ° C. with the film adhered, and the film was peeled off while maintaining the temperature. The same operation was performed 20 times on 20 semiconductor wafers. None of the wafers damaged during grinding and water invaded between the wafer and the adhesive film, but four wafers were damaged during peeling. [Table 3] shows the adhesive properties of the obtained adhesive film under the use conditions of Comparative Example 11, the contamination to semiconductor wafers, and the grinding results.
[0085]
Comparative Example 12
Using the pressure-sensitive adhesive film obtained in Comparative Example 10, in the same environment as in Example 1, in the same manner as in Example 1, the back surface of a semiconductor silicon wafer on which an integrated circuit is formed (same as in Example 1) Was ground until the thickness of the wafer became 200 μm. After the grinding, the film was peeled at room temperature. The above operation was performed 20 times on 20 semiconductor wafers. None of the wafers damaged during grinding and water invaded between the wafer and the adhesive film, but ten wafers were damaged during peeling. [Table 3] shows the adhesive properties of the obtained adhesive film under the use conditions of Comparative Example 12, the contamination to semiconductor wafers, and the grinding results.
[0086]
Comparative Example 13
6.5 parts by weight of an isocyanate-based cross-linking agent (Olester P49-60SX, manufactured by Mitsui Toatsu Chemicals, Inc., solid content 60%) was added to 100 parts by weight of the solution of polymer 1 (solid content 40% by weight) synthesized in Preparation Example 1. A part by weight was added to obtain an adhesive coating solution. This pressure-sensitive adhesive coating solution was applied to a polypropylene film (release film, thickness: 50 μm) using a roll coater, and dried at 120 ° C. for 1 minute to provide a 15 μm-thick pressure-sensitive adhesive layer. Then, the treated surface of an ethylene-vinyl acetate copolymer film (Shore D type hardness: 38) having a thickness of 120 μm that has been subjected to corona discharge treatment is bonded and pressed to transfer the pressure-sensitive adhesive layer, whereby the pressure-sensitive adhesive layer is transferred. Manufactured.
[0087]
In the same environment as in Example 1, the back surface of the semiconductor silicon wafer on which the integrated circuit was formed (same as in Example 1) was ground by the same method as in Example 1 until the wafer thickness became 200 μm. After the grinding, the film was peeled at room temperature. The same operation was performed 20 times on 20 semiconductor wafers. During the grinding, three wafers were damaged, and water intrusion was observed between the wafer and the adhesive film on all the remaining wafers (17 wafers) that were not damaged. There was no breakage of the wafer when the tape was peeled from the wafer in which water intrusion was recognized. The adhesive properties of the obtained adhesive film under the use conditions of Comparative Example 13, the contamination to the semiconductor wafer surface, and the grinding results are shown in [Table 3].
[0088]
Comparative Example 14
100 parts by weight of the solution of polymer 1 (solid content 40% by weight) synthesized in Preparation Example 1 was mixed with 2 parts by weight of an isocyanate-based crosslinking agent (Olester P49-60SX, manufactured by Mitsui Toatsu Chemicals, Inc., solid content 60%). And 6 parts by weight of dipentaerythritol monohydroxypentaacrylate and 0.4 part by weight of α-hydroxycyclohexylphenyl ketone were added to obtain an adhesive coating solution. This pressure-sensitive adhesive coating solution was applied to a polypropylene film (release film, thickness: 50 μm) using a roll coater, and dried at 120 ° C. for 1 minute to provide a 15 μm-thick pressure-sensitive adhesive layer. Then, the treated surface of an ethylene-vinyl acetate copolymer film (Shore D type hardness: 38) having a thickness of 120 μm that has been subjected to corona discharge treatment is bonded and pressed to transfer the pressure-sensitive adhesive layer, whereby the pressure-sensitive adhesive layer is transferred. Manufactured.
[0089]
In the same environment as in Example 1, the back surface of the semiconductor silicon wafer on which the integrated circuit was formed (same as in Example 1) was ground by the same method as in Example 1 until the wafer thickness became 200 μm. After the grinding was completed, light was irradiated from the ethylene-vinyl acetate copolymer film side of the adhesive film from a distance of 15 cm with a high-pressure mercury lamp (40 W / cm) for 20 seconds, and then the film was peeled at room temperature. The same operation was performed 20 times on 20 semiconductor wafers. None of the wafers was damaged during grinding, water invaded between the wafer and the adhesive film, or damaged during peeling. However, under microscopic observation, contaminants due to the adhesive were observed on the aluminum electrodes of some circuits. The adhesive properties of the obtained adhesive film under the use conditions of Comparative Example 14, the contamination to the semiconductor wafer surface, and the grinding results are shown in [Table 1].
[0090]
[Table 3]
【The invention's effect】
The pressure-sensitive adhesive film for grinding the backside of a semiconductor wafer of the present invention has a pressure-sensitive adhesive layer containing a crystalline polymer formed thereon, and when grinding the backside of the semiconductor wafer, protects and peels the semiconductor wafer with strong adhesive force. At this time, the adhesive strength is easily reduced by a simple operation such as cooling or heating. Therefore, cooling water does not enter between the semiconductor wafer and the adhesive film during the grinding operation, and the semiconductor wafer is not damaged. Further, since the peeling stress is small, the semiconductor wafer does not break when peeling. Further, contaminants from the pressure-sensitive adhesive layer hardly adhere to the surface of the semiconductor wafer after peeling. Therefore, the present invention exerts excellent effects in the technical field of increasing the diameter and thickness of a semiconductor wafer and improving the performance of an IC.
Claims (4)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30272695A JP3601892B2 (en) | 1995-11-21 | 1995-11-21 | Adhesive film for backside grinding of semiconductor wafer and method of using the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30272695A JP3601892B2 (en) | 1995-11-21 | 1995-11-21 | Adhesive film for backside grinding of semiconductor wafer and method of using the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH09148279A JPH09148279A (en) | 1997-06-06 |
| JP3601892B2 true JP3601892B2 (en) | 2004-12-15 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP30272695A Expired - Lifetime JP3601892B2 (en) | 1995-11-21 | 1995-11-21 | Adhesive film for backside grinding of semiconductor wafer and method of using the same |
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| JP (1) | JP3601892B2 (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4888928B2 (en) * | 2001-06-08 | 2012-02-29 | 日東電工株式会社 | Method for manufacturing ceramic green sheet, method for manufacturing multilayer ceramic electronic component, and carrier sheet for ceramic green sheet |
| JP5379453B2 (en) * | 2008-11-21 | 2013-12-25 | ニッタ株式会社 | Temperature-sensitive adhesive tape and chip-type electronic component manufacturing method using the same |
| JP6067348B2 (en) * | 2012-11-26 | 2017-01-25 | 株式会社ディスコ | Wafer processing method |
| JP6162976B2 (en) * | 2013-02-26 | 2017-07-12 | 東京応化工業株式会社 | Substrate processing method |
| JP6280403B2 (en) * | 2014-03-14 | 2018-02-14 | 日本碍子株式会社 | Polishing substrate manufacturing method |
| JP7053194B2 (en) * | 2017-09-04 | 2022-04-12 | ニッタ株式会社 | Heat-sensitive adhesives, temperature-sensitive adhesive sheets and temperature-sensitive adhesive tapes |
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1995
- 1995-11-21 JP JP30272695A patent/JP3601892B2/en not_active Expired - Lifetime
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| JPH09148279A (en) | 1997-06-06 |
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