JP2004153227A - Method of manufacturing ic chip - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing IC chips by which a wafer can be worked favorably into IC chips without uneven polishing by preventing the break, etc., of the wafer even when the wafer is extremely thin and improving the handleability of the wafer. <P>SOLUTION: This method of manufacturing IC chips includes a step of sticking a wafer to a substrate through a double-sided adhesive tape coated with an adhesive resin containing a gas generating agent which generates gas when the agent is stimulated and shows fluidity when the resin is heated and/or pressurized, a step of polishing the wafer while the wafer is fixed to the substrate through the adhesive tape, and a step of stimulating the adhesive tape to cause the gas generating agent to generate the gas. The method also includes a step of peeling the adhesive tape from the wafer. In the step of sticking the wafer to the substrate through the adhesive tape, the clearance produced in the peripheral area of the wafer and substrate is filled up by making the adhesive resin to flow by performing at least either one of heating and pressurization on the resin before and after or when the wafer is stuck to the substrate. <P>COPYRIGHT: (C)2004,JPO

Description

【００１９】
式（１）中、Ｒ^１及びＲ^２は、それぞれ低級アルキル基を表し、Ｒ^３は、炭素数２以上の飽和アルキル基を表す。なお、Ｒ^１とＲ^２は、同一であっても、異なっていてもよい。
上記一般式（１）で表されるアゾアミド化合物は、熱分解温度が高いことから、工程１におけるウエハと支持板との貼り合わせの際に上記接着樹脂の流動化のために加熱が必要な場合にも気体が発生してしまうことがなく、また、上記接着樹脂への溶解性にも優れている。
【００２０】
上記アゾ化合物は、光、熱等による刺激により窒素ガスを発生する。
上記アジド化合物としては、例えば、３−アジドメチル−３−メチルオキセタン、テレフタルアジド、ｐ−ｔｅｒｔ−ブチルベンズアジド等や、３−アジドメチル−３−メチルオキセタンを開環重合することにより得られるグリシジルアジドポリマー等のアジド基を有するポリマー等が挙げられる。これらのアジド化合物は、光、熱及び衝撃等による刺激により窒素ガスを発生する。
【００２１】
これらの気体発生剤のうち、上記アジド化合物は衝撃を与えることによっても容易に分解して窒素ガスを放出することから、取り扱いが困難であるという問題がある。更に、上記アジド化合物は、いったん分解が始まると連鎖反応を起こして爆発的に窒素ガスを放出しその制御ができないことから、爆発的に発生した窒素ガスによってウエハが損傷することがあるという問題もある。このような問題から上記アジド化合物の使用量は限定されるが、限定された使用量では充分な効果が得られないことがある。
【００２２】
一方、上記アゾ化合物は、アジド化合物とは異なり衝撃によっては気体を発生しないことから取り扱いが極めて容易である。また、連鎖反応を起こして爆発的に気体を発生することもないためウエハを損傷することもなく、光の照射を中断すれば気体の発生も中断できることから、用途に合わせた接着性の制御が可能であるという利点もある。従って、上記気体発生剤としては、アゾ化合物を用いることがより好ましい。
【００２３】
接着樹脂１００重量部当たり、気体発生剤は５重量部〜５０重量部の割合で含有されることが望ましい。５重量部を下回る場合には、ガス発生量が不足し、所望の剥離性が得られないことがある。また、５０重量部を上回る場合には、溶解性が悪化し、ブリード等の不具合が発生することがある。
【００２４】
上記気体発生剤は上記接着樹脂の全体に含有されていてもよいが、気体発生剤を接着樹脂の全体に含有させておくと、接着樹脂の全体が発泡体となるため柔らかくなりすぎ、両面接着テープをうまく剥がせなくなるおそれがある。従って、上記気体発生剤は、接着樹脂の表面部分にのみ含有されていることが好ましい。表面部分にのみ含有させておけば、接着樹脂の全体が発泡体とならずに、被着体との接着面で気体発生剤から気体が発生することにより接着面積を減少させ、なおかつ気体が、被着体と接着脂層との接着面の少なくとも一部を剥がし接着力を低下させる。
【００２５】
なお、上記表面部分とは、接着樹脂からなる層の厚さにもよるが、接着樹脂からなる層の表面から２０μｍまでの部分であることが好ましく、該表面部分において、接着樹脂１００重量部当たり、気体発生剤は５重量部〜５０重量部の割合で含有されることが望ましい。また、ここでいう表面部分にのみ含有されるとは、例えば、接着樹脂層の表面に付着した気体発生剤が樹脂と相溶して樹脂層に吸収された態様、接着樹脂層の表面に気体発生剤が均一に付着している態様等が挙げられる。
【００２６】
上記接着樹脂の表面部分にのみ気体発生剤を含有させる方法としては、例えば、両面接着テープの最外層に１〜２０μｍ程度の厚さで気体発生剤を含有する樹脂を塗工する方法や、あらかじめ作製した両面接着テープの少なくとも一方の面の表面に、気体発生剤を含有する揮発性液体を塗布するかスプレー等によって吹き付けることにより、表面に気体発生剤を均一に付着させる方法等が挙げられる。
【００２７】
また、気体発生剤を含有する表面部分とそれ以外とは、異なる組成の樹脂成分からなることが好ましく、なかでも、異なる極性を有する樹脂成分からなることがより好ましい。これにより、表面部分の気体発生剤がそれ以外に移行することを防止するか、移行しにくくすることができる。
【００２８】
上記気体発生剤は、接着樹脂中に粒子として存在しないことが好ましい。なお、本明細書において、気体発生剤が粒子として存在しないとは、電子顕微鏡により気体発生剤を含有する接着樹脂の断面を観察したときに気体発生剤を確認することができないことを意味する。上記接着樹脂中に気体発生剤が粒子として存在すると、気体を発生させる刺激として光を照射したときに粒子の界面で光が散乱して気体発生効率が低くなってしまったり、上記両面接着テープの表面平滑性が悪くなったりすることがある。
【００２９】
上記気体発生剤を粒子として存在しないようにするには、通常、接着樹脂中に溶解する気体発生剤を選択するが、接着樹脂中に溶解しない気体発生剤を選択する場合には、例えば、分散機を用いたり、分散剤を併用したりすることにより接着樹脂層中に気体発生剤を微分散させる。
【００３０】
また、上記気体発生剤は、微小な粒子であることが好ましい。更に、これらの微粒子は、例えば、分散機や混練装置等を用いて必要に応じてより細かい微粒子とすることが好ましい。
【００３１】
上記気体発生剤から発生した気体は接着樹脂の外へ放出されることが好ましい。これにより、上記両面接着テープに光等の刺激を与えると気体発生剤から発生した気体が被着体から接着樹脂の接着面の少なくとも一部を剥がし接着力を低下させるため、容易に被着体を剥離することができる。この際、気体発生剤から発生した気体の大部分は接着樹脂の外へ放出されることが好ましい。上記気体発生剤から発生した気体の大部分が接着樹脂の外へ放出されないと、接着樹脂が気体発生剤から発生した気体により全体的に発泡してしまい、接着力を低下させる効果を充分に得ることができず、被着体にのり残りを生じさせてしまうことがある。
【００３２】
なお、被着体に糊残りを生じさせない程度であれば、気体発生剤から発生した気体の一部が接着樹脂の中に溶け込んでいたり、気泡として接着樹脂中に存在していたりしてもかまわない。
【００３３】
上記接着樹脂は、上記気体発生剤としてアジド化合物又はアゾ化合物等の光による刺激により気体を発生する気体発生剤を用いる場合には、更に光増感剤も含有することが好ましい。上記光増感剤は、上記気体発生剤への光による刺激を増幅する効果を有することから、より少ない光の照射により気体を放出させることができる。また、より広い波長領域の光により気体を放出させることができるので、支持板がポリエチレンテレフタレート等のアジド化合物又はアゾ化合物から気体を発生させる波長の光を透過しないものであっても、支持板越しに光を照射して気体を発生させることができ支持板の選択の幅が広がる。
【００３４】
上記光増感剤としては特に限定されないが、例えば、チオキサントン増感剤等が好適である。なお、チオキサントン増感剤は、光重合開始剤としても用いることができる。
【００３５】
上記気体発生剤を含有する接着樹脂は、加熱又は加圧の少なくともいずれかにより流動性を示すものである。
加熱又は加圧の少なくともいずれかにより流動性を示す接着樹脂を用いることにより、接着樹脂が流動性を示す条件下でウエハとの貼り合わせを行えば、ウエハと支持板との周辺部に生じた隙間を充填することができる。なお、本明細書において加熱により流動性を示すとは、加熱しない状態においては固体状であるが、加熱することにより凹凸に追随できる程度の硬さになることを意味する。すなわち、ホットメルト型接着樹脂であることを意味する。また、加圧により流動性を示すとは、加圧すれば凹凸に追随する程度の柔らかさを有する接着樹脂を意味する。
【００３６】
また、上記接着樹脂は、刺激により架橋する未架橋の樹脂であることが好ましい。刺激により架橋する未架橋の樹脂を用いることにより、接着樹脂が流動性を示す条件下でウエハとの貼り合わせを行った後、刺激を与えて一部を架橋すれば、樹脂をある程度硬化させてウエハと支持板とを強固に固定することができる。なお、上記接着樹脂を架橋させる刺激としては特に限定されず、上記気体発生剤から気体を発生させる刺激と同一であってもよいし、異なっていてもよい。
【００３７】
上記接着樹脂としては特に限定されないが、例えば、熱可塑性樹脂や、硬化性樹脂等が好適である。
上記熱可塑性樹脂としては特に限定されず、例えば、ポリ（メタ）アクリル酸エステル樹脂、ポリエステル樹脂、ポリビニルアルコール樹脂、ポリ酢酸ビニル樹脂等が挙げられる。これらの熱可塑性樹脂は、単独で用いられてもよく、２種以上が併用されてもよい。
【００３８】
上記熱可塑性樹脂のなかでも、刺激により架橋する未架橋の樹脂としては、例えば、分子内にラジカル重合性の不飽和結合を有してなるアクリル酸アルキルエステル系及び／又はメタクリル酸アルキルエステル系の重合性ポリマーと、ラジカル重合性の多官能オリゴマー又はモノマーとを主成分とし、必要に応じて光重合開始剤を含んでなる光硬化型粘着剤や、分子内にラジカル重合性の不飽和結合を有してなるアクリル酸アルキルエステル系及び／又はメタクリル酸アルキルエステル系の重合性ポリマーと、ラジカル重合性の多官能オリゴマー又はモノマーとを主成分とし、熱重合開始剤を含んでなる熱硬化型粘着剤等が挙げられる。
【００３９】
このような光硬化型粘着剤又は熱硬化型粘着剤等の後硬化型粘着剤は、光の照射又は加熱により粘着剤の全体が均一にかつ速やかに重合架橋して一体化するため、重合硬化による弾性率の上昇が著しくなり、粘着力が大きく低下する。また、硬い硬化物中で気体発生剤から気体を発生させると、発生した気体の大半は外部に放出され、放出された気体は、被着体から本発明の接着性物質の接着面の少なくとも一部を剥がし接着力を低下させる。
【００４０】
上記重合性ポリマーは、例えば、分子内に官能基を持った（メタ）アクリル系ポリマー（以下、官能基含有（メタ）アクリル系ポリマーという）をあらかじめ合成し、分子内に上記の官能基と反応する官能基とラジカル重合性の不飽和結合とを有する化合物（以下、官能基含有不飽和化合物という）と反応させることにより得ることができる。
【００４１】
上記官能基含有（メタ）アクリル系ポリマーは、常温で粘着性を有するポリマーとして、一般の（メタ）アクリル系ポリマーの場合と同様に、アルキル基の炭素数が通常２〜１８の範囲にあるアクリル酸アルキルエステル及び／又はメタクリル酸アルキルエステルを主モノマーとし、これと官能基含有モノマーと、更に必要に応じてこれらと共重合可能な他の改質用モノマーとを常法により共重合させることにより得られるものである。上記官能基含有（メタ）アクリル系ポリマーの重量平均分子量は通常２０万〜２００万程度である。
【００４２】
上記官能基含有モノマーとしては、例えば、アクリル酸、メタクリル酸等のカルボキシル基含有モノマー；アクリル酸ヒドロキシエチル、メタクリル酸ヒドロキシエチル等のヒドロキシル基含有モノマー；アクリル酸グリシジル、メタクリル酸グリシジル等のエポキシ基含有モノマー；アクリル酸イソシアネートエチル、メタクリル酸イソシアネートエチル等のイソシアネート基含有モノマー；アクリル酸アミノエチル、メタクリル酸アミノエチル等のアミノ基含有モノマー等が挙げられる。
【００４３】
上記共重合可能な他の改質用モノマーとしては、例えば、酢酸ビニル、アクリロニトリル、スチレン等の一般の（メタ）アクリル系ポリマーに用いられている各種のモノマーが挙げられる。
【００４４】
上記官能基含有（メタ）アクリル系ポリマーに反応させる官能基含有不飽和化合物としては、上記官能基含有（メタ）アクリル系ポリマーの官能基に応じて上述した官能基含有モノマーと同様のものを使用できる。例えば、上記官能基含有（メタ）アクリル系ポリマーの官能基がカルボキシル基の場合はエポキシ基含有モノマーやイソシアネート基含有モノマーが用いられ、同官能基がヒドロキシル基の場合はイソシアネート基含有モノマーが用いられ、同官能基がエポキシ基の場合はカルボキシル基含有モノマーやアクリルアミド等のアミド基含有モノマーが用いられ、同官能基がアミノ基の場合はエポキシ基含有モノマーが用いられる。
【００４５】
上記多官能オリゴマー又はモノマーとしては、分子量が１万以下であるものが好ましく、より好ましくは加熱又は光の照射による粘着剤層の三次元網状化が効率よくなされるように、その分子量が５０００以下でかつ分子内のラジカル重合性の不飽和結合の数が２〜２０個のものである。このようなより好ましい多官能オリゴマー又はモノマーとしては、例えば、トリメチロールプロパントリアクリレート、テトラメチロールメタンテトラアクリレート、ペンタエリスリトールトリアクリレート、ペンタエリスリトールテトラアクリレート、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、ジペンタエリスリトールヘキサアクリレート又は上記同様のメタクリレート類等が挙げられる。その他、１，４−ブチレングリコールジアクリレート、１，６−ヘキサンジオールジアクリレート、ポリエチレングリコールジアクリレート、市販のオリゴエステルアクリレート、上記同様のメタクリレート類等が挙げられる。これらの多官能オリゴマー又はモノマーは、単独で用いられてもよく、２種以上が併用されてもよい。
【００４６】
上記光重合開始剤としては、例えば、２５０〜８００ｎｍの波長の光を照射することにより活性化されるものが挙げられ、このような光重合開始剤としては、例えば、メトキシアセトフェノン等のアセトフェノン誘導体化合物；ベンゾインプロピルエーテル、ベンゾインイソブチルエーテル等のベンゾインエーテル系化合物；ベンジルジメチルケタール、アセトフェノンジエチルケタール等のケタール誘導体化合物；フォスフィンオキシド誘導体化合物；ビス（η５−シクロペンタジエニル）チタノセン誘導体化合物、ベンゾフェノン、ミヒラーケトン、クロロチオキサントン、トデシルチオキサントン、ジメチルチオキサントン、ジエチルチオキサントン、α−ヒドロキシシクロヘキシルフェニルケトン、２−ヒドロキシメチルフェニルプロパン等の光ラジカル重合開始剤が挙げられる。これらの光重合開始剤は、単独で用いられてもよく、２種以上が併用されてもよい。
【００４７】
上記熱重合開始剤としては、熱により分解し、重合硬化を開始する活性ラジカルを発生するものが挙げられ、例えば、ジクミルパーオキサイド、ジ−ｔ−ブチルパーオキサイド、ｔ−ブチルパーオキシベンゾエール、ｔ−ブチルハイドロパーオキサイド、ベンゾイルパーオキサイド、クメンハイドロパーオキサイド、ジイソプロピルベンゼンハイドロパーオキサイド、パラメンタンハイドロパーオキサイド、ジ−ｔ−ブチルパーオキサイド等が挙げられる。なかでも、熱分解温度が高いことから、クメンハイドロパーオキサイド、パラメンタンハイドロパーオキサイド、ジ−ｔ−ブチルパーオキサイド等が好適である。これらの熱重合開始剤のうち市販されているものとしては特に限定されないが、例えば、パーブチルＤ、パーブチルＨ、パーブチルＰ、パーメンタＨ（以上いずれも日本油脂製）等が好適である。これら熱重合開始剤は、単独で用いられてもよく、２種以上が併用されてもよい。
【００４８】
なお、これらの後硬化型粘着剤は、ホットメルト型ポリマーを主成分として含有させた場合には、加熱により流動性を示すホットメルト型粘着剤として用いることができ、また、オリゴマー成分の割合を高めた場合には、加圧により流動性を示す柔らかい粘着剤として用いることができる。
【００４９】
上記後硬化型粘着剤には、以上の成分のほか、本発明の目的を損なわない限りにおいて、粘着剤としての凝集力の調節を図る目的で、所望によりイソシアネート化合物、メラミン化合物、エポキシ化合物等の一般の粘着剤に配合される各種の多官能性化合物を適宜配合してもよい。また、可塑剤、樹脂、界面活性剤、ワックス、微粒子充填剤等の公知の添加剤を加えることもできる。
【００５０】
上記硬化性樹脂としては特に限定されず、例えば、熱硬化性樹脂、光硬化性樹脂等が挙げられる。上記熱硬化性樹脂としては特に限定されず、例えば、エポキシ樹脂、ポリウレタン樹脂等が挙げられる。また、上記光硬化性樹脂としては特に限定されず、例えば、感光性オニウム塩等の光カチオン触媒を含有するエポキシ樹脂や感光性ビニル基を有するアクリル樹脂等が挙げられる。
【００５１】
なお、これらの硬化性樹脂は未架橋のものが好ましいが、樹脂層を形成するためにある程度の凝集力を要する場合には、必要とされる程度の架橋が施されていてもよい。
【００５２】
上記接着樹脂はゲル分率が５％以下であることが好ましい。ゲル分率が５％を超えると、加熱又は加圧した際の流動性が乏しくウエハと支持板との周辺部に生じる隙間を充分に充填できないことがある。より好ましくは０％である。
【００５３】
本発明のＩＣチップの製造方法では、まず、上記両面接着テープを介してウエハと支持板とを貼り合わせる工程１を行う。
この際、貼り合わせる前後又は貼り合わせと同時に加熱又は加圧の少なくともいずれかにより接着樹脂を流動させウエハと支持板との周辺部に生じた隙間を充填する。なお、貼り合わせと加熱及び／又は加圧の順序は特に限定されず、例えば、貼り合わせと同時に加熱を行ってもよく、貼り合わせの前後に加熱を行ってもよい。また、貼り合わせと同時に加圧を行ってもよく、貼り合わせの前後に加圧を行ってもよい。
【００５４】
上記ウエハとしては、例えば、シリコン、ガリウム砒素等の半導体からなるものが挙げられる。
上記ウエハの厚さとしては特に限定されないが、ウエハが薄いほど本発明の破損防止の効果が発揮されやすく、研磨後の厚さが５０μｍ程度、例えば、２０〜８０μｍの厚さの半導体ウエハである場合に優れた破損防止の効果が得られる。また、上記ウエハの周辺部には、ウエハを加工したり運搬したりする際にウエハを保持するため、１２〜１５μｍ程度厚さが薄くなるように段差が作られている。
【００５５】
上記支持板としては特に限定されないが、上記気体発生剤から気体を発生させる刺激が光である場合には透明であることが好ましく、例えば、ガラス板；アクリル、オレフィン、ポリカーボネート、塩化ビニル、ＡＢＳ、ポリエチレンテレフタレート（ＰＥＴ）、ナイロン、ウレタン、ポリイミド等の樹脂からなる板状体等が挙げられる。
【００５６】
上記支持板の厚さの好ましい下限は５００μｍ、好ましい上限は３ｍｍであり、より好ましい下限は１ｍｍ、より好ましい上限は２ｍｍである。また、上記支持板の厚さのばらつきは、１％以下であることが好ましい。
【００５７】
次いで、上記両面接着テープを介して支持板に固定した状態でウエハを研磨する工程２を行う。上記研磨の方法としては特に限定されず、通常のＩＣチップの製造方法において用いられる方法を用いることができ、例えば、支持板を固定し、高速回転する研磨用砥石を用いて切削水をかけながら完成時のチップの厚さにまでウエハを研磨する方法等が挙げられる。本発明のＩＣチップの製造方法においては、上述のように両面接着テープの接着樹脂がウエハと支持板との周辺部に生じた隙間を充填することから、水が浸入することもなく、研磨ムラなく良好に研磨することができる。
【００５８】
上記接着樹脂が刺激により架橋する未架橋の樹脂である場合には、工程２に先立って、更に、両面接着テープに刺激を与えて刺激により架橋する接着樹脂の一部を架橋させる工程を有することが好ましい。上記接着樹脂の一部を架橋することにより、ウエハと支持板とが更に強固に固定され、後の研磨工程で剥がれてしまうことがなくなる。また、架橋することにより、上記接着樹脂がホットメルト型接着樹脂である場合でも、耐熱性が向上し、後の研磨工程において摩擦熱により加熱されても再び流動化してウエハと支持板とが剥がれてしまうこともない。
【００５９】
上記架橋の程度としては、流動化せずウエハと支持板とを固定できる程度に止めることが好ましい。完全に硬化させてしまうとかえって接着力を失いウエハと両面接着テープが剥がれてしまうことがある。
【００６０】
本発明のＩＣチップの製造方法では、次いで、上記両面接着テープに刺激を与える工程３及びウエハから両面接着テープを剥離する工程４を行う。上記両面接着テープに刺激を与えることにより、樹脂組成物層中の気体発生剤から気体を発生させてウエハ又は支持板と両面接着テープとの接着面に放出させ、ウエハ又は支持板から樹脂層の接着面の少なくとも一部を剥がし、樹脂層の接着力を低下させることができるので、気体発生剤を含有する樹脂層と貼り合わせられたウエハ又は支持板を容易に剥離することができる。
【００６１】
また、上記両面接着テープの支持板と貼り合わせた側の面に気体発生剤を含有させた場合には、両面接着テープをウエハから剥離するに先立って、刺激を与えて支持板と両面接着テープの間の気体発生剤から気体を発生させて接着力を低下させ、硬い支持板を両面接着テープから剥離することにより、両面接着テープは可とう性を有するテープとなり、両面接着テープをめくりながらウエハから剥がすことができる。
【００６２】
上記刺激を与える方法としては特に限定されず、例えば、紫外線による刺激により気体を発生する気体発生剤を用いている場合には、支持板側から紫外線を照射する方法等が挙げられる。
【００６３】
なお、通常の工程では研磨工程終了後刺激を与えて気体を発生させてウエハを剥離する前に、研磨したウエハにダイシングテープを貼り付け、その後ウエハを剥離してからダイシングを行う。
【００６４】
また、本発明のＩＣチップの製造方法では、必要に応じて、通常行われる工程を省略したり、工程の順序を通常と異なるものとしたりしてもよく、例えば、あらかじめダイシングを行った後に研磨工程を行い、ウエハをチップ状にしてもよい。
【００６５】
【実施例】
以下に実施例を掲げて本発明を更に詳しく説明するが、本発明はこれら実施例のみに限定されるものではない。
【００６６】
（実施例１）
＜粘着剤の調製＞
下記の化合物を酢酸エチルに溶解させ、紫外線を照射して重合を行い、重量平均分子量７０万のアクリル共重合体を得た。
【００６７】
得られたアクリル共重合体を含む酢酸エチル溶液の樹脂固形分１００重量部に対して、２−イソシアナトエチルメタクリレート３．５重量部を加えて反応させ、更に、反応後の酢酸エチル溶液の樹脂固形分１００重量部に対して、ペンタエリスリトールトリアクリレート４０重量部、光重合開始剤（イルガキュア６５１）５重量部を混合し粘着剤（１）の酢酸エチル溶液を調製した。
ブチルアクリレート ７９重量部
エチルアクリレート １５重量部
アクリル酸 １重量部
２−ヒドロキシエチルアクリレート ５重量部
光重合開始剤 ０．２重量部
（イルガキュア６５１、５０％酢酸エチル溶液）
ラウリルメルカプタン ０．０１重量部
粘着剤（１）の酢酸エチル溶液の樹脂固形分１００重量部に対して、２，２’−アゾビス−（Ｎ−ブチル−２−メチルプロピオンアミド）３０重量部、及び、２，４−ジエチルチオキサントン３．６重量部を混合して、気体発生剤を含有する粘着剤（２）を調製した。
【００６８】
＜両面粘着テープの作製＞
粘着剤（２）の酢酸エチル溶液を、両面にコロナ処理及びエンボス加工が施された厚さ３８μｍポリエチレンテレフタレート（ＰＥＴ）フィルムのエンボス加工が施されていない片面に乾燥皮膜の厚さが約５０μｍとなるようにドクターナイフで塗工し１１０℃、５分間加熱して塗工溶液を乾燥させた。乾燥後の粘着剤層は乾燥状態で粘着性を示した。次いで、粘着剤（２）層の表面に離型処理が施されたＰＥＴフィルムを貼り付けた。
【００６９】
粘着剤（１）の酢酸エチル溶液を、表面に離型処理が施されたＰＥＴフィルムの上に乾燥皮膜の厚さが約３０μｍとなるようにドクターナイフで塗工し１１０℃、５分間加熱して溶剤を揮発させ塗工溶液を乾燥させた。乾燥後の粘着剤層は乾燥状態で粘着性を示した。
【００７０】
次いで、粘着剤（２）層を設けたＰＥＴフィルムの粘着剤（２）層のない側の面と、粘着剤（１）層を設けたＰＥＴフィルムの粘着剤（１）層の面とを貼り合わせた。その後、４０℃、３日間静置養生を行った。
【００７１】
これにより両面に粘着剤層が設けられ、その表面が離型処理が施されたＰＥＴフィルムで保護された両面粘着テープ１を得た。両面粘着テープ１の粘着剤層はいずれも透明であった。
【００７２】
＜ＩＣチップの製造＞
（シリコンウエハとガラス板との貼り合わせ工程）
両面粘着テープ１の粘着剤（２）層を保護するＰＥＴフィルムを剥がし、直径２０ｃｍ、厚さ約７５０μｍで、表面に形成された回路の凹凸が５μｍ、周辺部が１５μｍであるシリコンウエハの回路が形成された面にラミネーターを用いて貼り付けた後、シリコンウエハの大きさに合わせて両面粘着テープ１を切断した。
【００７３】
次に、粘着剤（１）層を保護するＰＥＴフィルムを剥がし、直径２０．４ｃｍのガラス板を粘着剤（１）層に真空プレス装置を用いて貼り付けた。次いで、６０℃で２分間予熱した後、加熱プレス装置を用いて６０℃、９８Ｎ／ｃｍ^２で１分間加熱プレスを行った。両面接着テープはウエハとガラス板のいずれにも密着しており、ウエハの周辺部にも隙間は見られなかった。
【００７４】
（紫外線照射工程）
ガラス板側から超高圧水銀灯を用いて、３６５ｎｍの紫外線をガラス板表面への照射強度が１０ｍＷ／ｃｍ^２となるよう照度を調節して２秒間照射した。
【００７５】
（研磨工程）
ガラス板で補強されたシリコンウエハを研磨装置に取り付け、シリコンウエハの厚さが約５０μｍになるまで研磨した。このときガラス板から観察した限りでは、シリコンウエハと両面接着テープとの間への水の浸入は全く認められなかった。
【００７６】
研磨装置からシリコンウエハを取り外し、ダイシングテープをシリコンウエハの上に貼り付けた。
（紫外線照射工程）
ガラス板側から超高圧水銀灯を用いて、３６５ｎｍの紫外線をガラス板表面への照射強度が４０ｍＷ／ｃｍ^２となるよう照度を調節して２分間照射した。
【００７７】
（ウエハの剥離工程）
シリコンウエハを固定し、ガラス板を真上に引っ張って両面接着テープとともにシリコンウエハから剥がした。
【００７８】
（ダイシング工程）
続いて、ダイシングテープで補強されたシリコンウエハをダイシング装置に取り付け、ウエハ側からカッター刃を切り入れシリコンウエハをＩＣチップの大きさに切断した。次いで、ダイシングテープからＩＣチップを剥がしＩＣチップを取りだした。
【００７９】
【発明の効果】
本発明によれば、厚さ５０μｍ程度の極めて薄いウエハであってもウエハの破損等を防止し、取り扱い性を改善し、研磨ムラなく良好にＩＣチップへの加工が行えるＩＣチップの製造方法を提供できる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing an IC chip which can prevent breakage of the wafer even if the wafer is extremely thin, having a thickness of about 50 μm, improve the handleability, and can process the IC chip satisfactorily without uneven polishing.
[0002]
[Prior art]
A semiconductor integrated circuit (IC chip) is usually formed by slicing a rod-shaped high-purity semiconductor single crystal into a wafer, forming a predetermined circuit pattern on the wafer surface using a photoresist, and then polishing the back surface of the wafer. It is manufactured by polishing with a machine to reduce the thickness of the wafer to about 100 to 600 μm, and finally dicing it into chips.
[0003]
At the time of the above-mentioned polishing, an adhesive sheet (polishing tape) is attached to the wafer surface to prevent breakage of the wafer and to facilitate the polishing process. Sheets (dicing tape) are adhered, and the wafer is diced in a state where the wafer is bonded and fixed. The formed chip is pushed up with a needle from the film substrate side of the dicing tape and picked up, and fixed on the die pad.
[0004]
In recent years, as the use of IC chips has expanded, an extremely thin semiconductor wafer having a thickness of about 50 μm that can be used for IC cards or stacked and used has been required. However, a semiconductor wafer having a thickness of about 50 μm has a larger warp than a conventional semiconductor wafer having a thickness of about 100 to 600 μm and is more likely to be broken by an impact. Then, it may be damaged.
[0005]
A semiconductor wafer having a thickness of about 50 μm has a high risk of being damaged in a polishing process or a dicing process, which is easily affected by an impact, and is also easily damaged when a bump is formed on an electrode of an IC chip. For this reason, it has become an important issue to improve the handleability of the wafer in the process of manufacturing IC chips from a thin semiconductor wafer having a thickness of about 50 μm.
[0006]
[Problems to be solved by the invention]
On the other hand, the inventors of the present invention have conducted intensive studies and, as a result, have improved the handleability of an extremely thin wafer having a thickness of about 50 μm by fixing the wafer to a support plate via a double-sided adhesive tape. The double-sided pressure-sensitive adhesive tape is made of a pressure-sensitive adhesive containing a gas generating agent that generates a gas upon stimulation, so that a stimulus is given after polishing to remove the support plate from the wafer. Has been found to be able to be easily peeled off and to be favorably processed into an IC chip. According to this method for manufacturing an IC chip, even if the wafer is polished to a thickness of 50 μm or less, the handle is excellent, there is no breakage, and the support plate can be easily peeled off after processing, and the workability is good. Processing into an IC chip can be performed.
[0007]
However, in order to hold the wafer at the time of processing or transporting the wafer, the peripheral portion of the wafer is formed with a step so that the thickness is reduced by about 12 to 15 μm. Therefore, when the wafer is fixed to the support plate via the double-sided adhesive tape, a large gap is generated around the wafer and the support plate. Also, if the wafer and the double-sided adhesive tape are adhered in advance without any gap, the double-sided adhesive tape follows the shape of the wafer, so a gap is generated between the double-sided adhesive tape and the support plate or between the double-sided adhesive tape and the wafer. I will. Usually, the polishing process is performed while water is applied to suppress a rise in temperature due to frictional heat, but if there is such a gap between the double-sided adhesive tape and the wafer, water penetrates into the gap, and the double-sided adhesive tape is However, there has been a problem that the wafer may be peeled off, or the wafer may be distorted by water that has entered, resulting in uneven polishing.
[0008]
The present invention has been made in view of the above circumstances, and has been developed to provide an IC chip capable of preventing breakage of a wafer even with an extremely thin wafer having a thickness of about 50 μm, improving handleability, and processing the IC chip without polishing unevenness. It is intended to provide a manufacturing method.
[0009]
[Means for Solving the Problems]
The present invention provides a double-sided adhesive containing at least a gas generating agent that generates a gas upon stimulation, and a surface made of an adhesive resin that exhibits fluidity by at least one of heat and pressure, which is formed on one or both surfaces. Step 1 of bonding a wafer having a step at the peripheral portion to a support plate via a tape, Step 2 of polishing the wafer while being fixed to the support plate via the double-sided adhesive tape 2, Step 2 A method of manufacturing an IC chip, comprising: a step (3) of applying a stimulus for generating a gas from a gas generating agent; and a step (4) of peeling the double-sided adhesive tape from the wafer. In the bonding step 1, the adhesive resin is caused to flow by heating or pressurizing before and after bonding or simultaneously with bonding. It is a manufacturing method of the IC chip to fill the gap formed in the periphery of the Movement and the support plate.
[0010]
Hereinafter, the present invention will be described in detail.
In the method of manufacturing an IC chip according to the present invention, first, in step 1, a wafer and a support plate are bonded via a double-sided adhesive tape. By fixing the wafer to the support plate, the handleability of the wafer is improved, and even if the wafer is polished to a thickness of 50 μm or less, the wafer is not broken and can be handled very easily. Can be processed into an IC chip.
[0011]
The double-sided adhesive tape may be a support tape in which layers made of an adhesive resin are formed on both sides of a base material, or a non-support tape having no base material. In the case of a non-support tape, it may be a single-layer adhesive resin layer or a multi-layer adhesive resin layer.
[0012]
When the stimulus for generating a gas from the gas generating agent is a stimulus by light, it is preferable that the base material transmit or pass light, for example, acrylic, olefin, polycarbonate, vinyl chloride, Examples include a sheet made of a transparent resin such as ABS, polyethylene terephthalate (PET), nylon, urethane, and polyimide, a sheet having a mesh-like structure, and a sheet having holes.
[0013]
The double-sided adhesive tape contains a gas generating agent that generates a gas upon stimulation, and has a surface formed of an adhesive resin that exhibits fluidity by at least one of heating or pressing, and is formed on one or both surfaces. is there. In the case where the surface made of the adhesive resin is formed on only one surface, the layer formed on the other surface is not particularly limited, and does not include, for example, the gas generating agent and at least heat or pressure. Layer made of adhesive resin showing fluidity by any of them: a layer made of an adhesive resin containing or not containing the above-mentioned gas generating agent, and the like.
[0014]
By containing the gas generating agent, the double-sided adhesive tape, when stimulated, generates gas from the gas generating agent and peels off at least a part of the bonding surface, so that the adhesive force is reduced and the adherend is Can be easily peeled off.
[0015]
Examples of the stimulus for generating a gas from the gas generating agent include stimuli by light, heat, ultrasonic waves, and the like. Among them, stimulation by light or heat is preferred. Examples of the light include ultraviolet light and visible light. In the case of using a light stimulus as the stimulus, it is preferable that the resin containing the gas generating agent can transmit or pass light.
[0016]
Although there is no particular limitation on the gas generating agent that generates gas by the above stimulus, for example, azo compounds and azide compounds are preferably used.
Examples of the azo compound include 2,2′-azobis (N-cyclohexyl-2-methylpropionamide), 2,2′-azobis [N- (2-methylpropyl) -2-methylpropionamide], , 2'-azobis (N-butyl-2-methylpropionamide), 2,2'-azobis [N- (2-methylethyl) -2-methylpropionamide], 2,2'-azobis (N-hexyl -2-methylpropionamide), 2,2'-azobis (N-propyl-2-methylpropionamide), 2,2'-azobis (N-ethyl-2-methylpropionamide), 2,2'-azobis {2-Methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] propionamide}, 2,2′-azobis {2-methyl-N- [2- (1-hydroxy Butyl)] propionamide}, 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) propionamide], 2,2′-azobis [N- (2-propenyl) -2-methylpropionamide ], 2,2'-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis [2- (2-imidazolin-2-yl) propane] Dihydrochloride, 2,2′-azobis [2- (2-imidazolin-2-yl) propane] disulfate dihydrolate, 2,2′-azobis [2- (3,4,5,6-tetra Hydropyrimidin-2-yl) propane] dihydrochloride, 2,2′-azobis {2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane} dihyd Lochloride, 2,2'-azobis [2- (2-imidazolin-2-yl) propane], 2,2'-azobis (2-methylpropionamidine) hydrochloride, 2,2'-azobis (2-aminopropane ) Dihydrochloride, 2,2′-azobis [N- (2-carboxyacyl) -2-methyl-propionamidine], 2,2′-azobis {2- [N- (2-carboxyethyl) amidine] propane ｝, 2,2′-azobis (2-methylpropionamide oxime), dimethyl 2,2′-azobis (2-methylpropionate), dimethyl 2,2′-azobisisobutyrate, 4,4′- Azobis (4-cyancarbonic acid), 4,4'-azobis (4-cyanopentanoic acid), 2,2'-azobis (2,4,4-trimethyl Pentane) and the like.
[0017]
Among them, 2,2'-azobis (N-cyclohexyl-2-methylpropionamide), 2,2'-azobis [N- (2-methylpropyl) -2-methylpropionamide], 2,2'-azobis (N-butyl-2-methylpropionamide), 2,2′-azobis [N- (2-methylethyl) -2-methylpropionamide], 2,2′-azobis (N-hexyl-2-methylpropion) Amide), 2,2′-azobis (N-propyl-2-methylpropionamide), 2,2′-azobis (N-ethyl-2-methylpropionamide) and the like represented by the following general formula (1). Azoamide compounds are preferred.
[0018]
Embedded image

[0019]
In the formula (1), R ¹ And R ² Each represents a lower alkyl group; ³ Represents a saturated alkyl group having 2 or more carbon atoms. Note that R ¹ And R ² May be the same or different.
Since the azoamide compound represented by the general formula (1) has a high thermal decomposition temperature, it is necessary to heat the adhesive resin for fluidization when bonding the wafer and the support plate in step 1. Also, no gas is generated, and the solubility in the adhesive resin is excellent.
[0020]
The azo compound generates nitrogen gas when stimulated by light, heat, or the like.
Examples of the azide compound include 3-azidomethyl-3-methyloxetane, terephthalazide, p-tert-butylbenzazide, and glycidyl azide polymer obtained by ring-opening polymerization of 3-azidomethyl-3-methyloxetane. And other polymers having an azide group. These azide compounds generate nitrogen gas when stimulated by light, heat, impact or the like.
[0021]
Among these gas generating agents, the azide compound described above has a problem that it is difficult to handle because it easily decomposes and gives off nitrogen gas even when subjected to impact. Furthermore, once the decomposition starts, the azide compound causes a chain reaction, explosively releases nitrogen gas, and the control cannot be performed. Therefore, there is a problem that the explosively generated nitrogen gas may damage the wafer. is there. Due to these problems, the amount of the azide compound used is limited, but a limited amount of use may not provide a sufficient effect.
[0022]
On the other hand, the azo compound, unlike the azide compound, does not generate gas by impact, and is therefore extremely easy to handle. In addition, since there is no explosive gas generated due to a chain reaction, the wafer is not damaged, and gas generation can be interrupted by interrupting light irradiation. There is also the advantage that it is possible. Therefore, it is more preferable to use an azo compound as the gas generating agent.
[0023]
It is desirable that the gas generating agent be contained in a ratio of 5 parts by weight to 50 parts by weight per 100 parts by weight of the adhesive resin. If the amount is less than 5 parts by weight, the amount of generated gas is insufficient, and the desired releasability may not be obtained. On the other hand, when the amount exceeds 50 parts by weight, the solubility is deteriorated, and problems such as bleeding may occur.
[0024]
The gas generating agent may be contained in the whole of the adhesive resin, but if the gas generating agent is contained in the whole of the adhesive resin, the whole of the adhesive resin becomes a foam, so that it becomes too soft, and the two-sided adhesive is used. There is a possibility that the tape cannot be peeled off properly. Therefore, it is preferable that the gas generating agent is contained only in the surface portion of the adhesive resin. If it is contained only in the surface part, the entire adhesive resin does not become a foam, the gas is generated from the gas generating agent on the surface to be bonded with the adherend, thereby reducing the bonding area, and the gas is At least a part of the adhesive surface between the adherend and the adhesive fat layer is peeled off to reduce the adhesive strength.
[0025]
The surface portion depends on the thickness of the layer made of the adhesive resin, but is preferably a portion up to 20 μm from the surface of the layer made of the adhesive resin. The gas generating agent is desirably contained at a ratio of 5 parts by weight to 50 parts by weight. The term “contained only in the surface portion” as used herein means, for example, a mode in which the gas generating agent attached to the surface of the adhesive resin layer is compatible with the resin and is absorbed by the resin layer. An embodiment in which the generator is uniformly attached is exemplified.
[0026]
As a method of containing a gas generating agent only on the surface portion of the adhesive resin, for example, a method of applying a resin containing a gas generating agent to the outermost layer of a double-sided adhesive tape in a thickness of about 1 to 20 μm, A method in which a volatile liquid containing a gas generating agent is applied to at least one surface of the produced double-sided adhesive tape or sprayed by a spray or the like to uniformly adhere the gas generating agent to the surface is exemplified.
[0027]
Further, the surface portion containing the gas generating agent and the other portion are preferably made of resin components having different compositions, and more preferably made of resin components having different polarities. Thereby, it is possible to prevent the gas generating agent on the surface portion from migrating to other portions or to make it difficult to migrate.
[0028]
It is preferable that the gas generating agent does not exist as particles in the adhesive resin. In this specification, the absence of the gas generating agent as particles means that the gas generating agent cannot be confirmed when the cross section of the adhesive resin containing the gas generating agent is observed with an electron microscope. When the gas generating agent is present as particles in the adhesive resin, when light is irradiated as a stimulus to generate gas, light is scattered at the interface of the particles and the gas generation efficiency becomes low, or the double-sided adhesive tape has The surface smoothness may be deteriorated.
[0029]
In order to prevent the gas generating agent from being present as particles, usually, a gas generating agent that dissolves in the adhesive resin is selected, but when a gas generating agent that does not dissolve in the adhesive resin is selected, for example, dispersion is performed. The gas generating agent is finely dispersed in the adhesive resin layer by using a machine or by using a dispersant in combination.
[0030]
Further, the gas generating agent is preferably fine particles. Further, it is preferable that these fine particles are made finer as necessary by using a disperser, a kneading device, or the like.
[0031]
The gas generated from the gas generating agent is preferably released to the outside of the adhesive resin. Accordingly, when a stimulus such as light is applied to the double-sided adhesive tape, the gas generated from the gas generating agent peels off at least a part of the adhesive surface of the adhesive resin from the adherend and lowers the adhesive force. Can be peeled off. At this time, it is preferable that most of the gas generated from the gas generating agent is released to the outside of the adhesive resin. Unless most of the gas generated from the gas generating agent is released to the outside of the adhesive resin, the adhesive resin is entirely foamed by the gas generated from the gas generating agent, and the effect of lowering the adhesive force is sufficiently obtained. Cannot be carried out, and a residue may be left on the adherend.
[0032]
In addition, as long as the adhesive residue is not generated on the adherend, a part of the gas generated from the gas generating agent may be dissolved in the adhesive resin or may be present as bubbles in the adhesive resin. Absent.
[0033]
When using a gas generating agent such as an azide compound or an azo compound which generates a gas upon stimulation with light as the gas generating agent, the adhesive resin preferably further contains a photosensitizer. Since the photosensitizer has an effect of amplifying the light stimulus to the gas generating agent, the gas can be released by irradiation with less light. Further, since gas can be released by light in a wider wavelength range, even if the support plate does not transmit light having a wavelength that generates gas from an azide compound or an azo compound such as polyethylene terephthalate, the support plate can pass through the support plate. A gas can be generated by irradiating the substrate with light, and the range of choice of the support plate can be expanded.
[0034]
The photosensitizer is not particularly limited, but, for example, a thioxanthone sensitizer is suitable. Note that the thioxanthone sensitizer can also be used as a photopolymerization initiator.
[0035]
The adhesive resin containing the gas generating agent exhibits fluidity by at least one of heating and pressing.
By using an adhesive resin showing fluidity by at least one of heating and pressurization, if the bonding with the wafer is performed under conditions where the adhesive resin shows fluidity, the adhesive resin is formed in the peripheral portion between the wafer and the support plate. The gap can be filled. In this specification, the expression "fluidity by heating" means that the material is in a solid state when not heated, but becomes hard enough to follow irregularities by heating. That is, it means a hot melt type adhesive resin. The expression "fluidity by pressurization" means an adhesive resin having such a softness that it can follow irregularities when pressurized.
[0036]
Further, the adhesive resin is preferably an uncrosslinked resin that is crosslinked by stimulation. By using an uncrosslinked resin that is crosslinked by stimulus, after bonding to the wafer under conditions where the adhesive resin shows fluidity, if a stimulus is applied to partially crosslink, the resin is cured to some extent The wafer and the support plate can be firmly fixed. The stimulus for crosslinking the adhesive resin is not particularly limited, and may be the same as or different from the stimulus for generating a gas from the gas generating agent.
[0037]
The adhesive resin is not particularly limited, but is preferably, for example, a thermoplastic resin, a curable resin, or the like.
The thermoplastic resin is not particularly limited, and examples thereof include a poly (meth) acrylate resin, a polyester resin, a polyvinyl alcohol resin, and a polyvinyl acetate resin. These thermoplastic resins may be used alone or in combination of two or more.
[0038]
Among the above thermoplastic resins, examples of the uncrosslinked resin which is crosslinked by stimulation include, for example, alkyl acrylate and / or methacrylate alkyl esters having a radical polymerizable unsaturated bond in the molecule. A photocurable pressure-sensitive adhesive containing a polymerizable polymer and a radically polymerizable polyfunctional oligomer or monomer as main components and optionally containing a photopolymerization initiator, or a radically polymerizable unsaturated bond in the molecule. Thermosetting adhesive comprising as main components an alkyl acrylate-based and / or alkyl methacrylate-based polymerizable polymer and a radically polymerizable polyfunctional oligomer or monomer and containing a thermal polymerization initiator Agents and the like.
[0039]
Post-curing pressure-sensitive adhesives such as light-curing pressure-sensitive adhesives or thermosetting pressure-sensitive adhesives are uniformly and quickly polymerized and cross-linked by light irradiation or heating, so that they are polymerized and cured. The increase in the modulus of elasticity is remarkable, and the adhesive strength is greatly reduced. Further, when a gas is generated from the gas generating agent in the hard cured product, most of the generated gas is released to the outside, and the released gas is at least one of the adhesive surfaces of the adhesive substance of the present invention from the adherend. Peel off the part to reduce the adhesive strength.
[0040]
As the polymerizable polymer, for example, a (meth) acrylic polymer having a functional group in a molecule (hereinafter referred to as a (meth) acrylic polymer containing a functional group) is synthesized in advance and reacted with the functional group in the molecule. (Hereinafter, referred to as a functional group-containing unsaturated compound) having a functional group and a radical polymerizable unsaturated bond.
[0041]
The functional group-containing (meth) acrylic polymer is a polymer having tackiness at room temperature, and is an acryl polymer having an alkyl group having a carbon number of usually 2 to 18 as in a general (meth) acrylic polymer. An acid alkyl ester and / or a methacrylic acid alkyl ester as a main monomer, and a functional group-containing monomer and, if necessary, another copolymerizable monomer copolymerizable therewith by a conventional method. It is obtained. The weight average molecular weight of the functional group-containing (meth) acrylic polymer is usually about 200,000 to 2,000,000.
[0042]
Examples of the functional group-containing monomer include a carboxyl group-containing monomer such as acrylic acid and methacrylic acid; a hydroxyl group-containing monomer such as hydroxyethyl acrylate and hydroxyethyl methacrylate; and an epoxy group-containing monomer such as glycidyl acrylate and glycidyl methacrylate. Monomers; isocyanate group-containing monomers such as isocyanate ethyl acrylate and isocyanate ethyl methacrylate; and amino group-containing monomers such as aminoethyl acrylate and aminoethyl methacrylate.
[0043]
Examples of other copolymerizable modifying monomers include various monomers used in general (meth) acrylic polymers such as vinyl acetate, acrylonitrile, and styrene.
[0044]
As the functional group-containing unsaturated compound to be reacted with the functional group-containing (meth) acrylic polymer, the same compound as the functional group-containing monomer described above according to the functional group of the functional group-containing (meth) acrylic polymer is used. it can. For example, when the functional group of the functional group-containing (meth) acrylic polymer is a carboxyl group, an epoxy group-containing monomer or an isocyanate group-containing monomer is used, and when the functional group is a hydroxyl group, an isocyanate group-containing monomer is used. When the functional group is an epoxy group, a carboxyl group-containing monomer or an amide group-containing monomer such as acrylamide is used. When the functional group is an amino group, an epoxy group-containing monomer is used.
[0045]
The polyfunctional oligomer or monomer preferably has a molecular weight of 10,000 or less, and more preferably has a molecular weight of 5,000 or less so that the three-dimensional network of the pressure-sensitive adhesive layer can be efficiently formed by heating or irradiation with light. And the number of radically polymerizable unsaturated bonds in the molecule is from 2 to 20. Such more preferred polyfunctional oligomers or monomers include, for example, trimethylolpropane triacrylate, tetramethylolmethanetetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol monohydroxypentaacrylate, dipentaerythritol hexaacrylate Alternatively, methacrylates similar to the above may be used. Other examples include 1,4-butylene glycol diacrylate, 1,6-hexanediol diacrylate, polyethylene glycol diacrylate, commercially available oligoester acrylates, and methacrylates similar to those described above. These polyfunctional oligomers or monomers may be used alone or in combination of two or more.
[0046]
Examples of the photopolymerization initiator include those activated by irradiation with light having a wavelength of 250 to 800 nm. Examples of such photopolymerization initiators include acetophenone derivative compounds such as methoxyacetophenone. Benzoin ether compounds such as benzoin propyl ether and benzoin isobutyl ether; ketal derivative compounds such as benzyl dimethyl ketal and acetophenone diethyl ketal; phosphine oxide derivative compounds; bis (η5-cyclopentadienyl) titanocene derivative compound, benzophenone and Michler's ketone , Chlorothioxanthone, todecylthioxanthone, dimethylthioxanthone, diethylthioxanthone, α-hydroxycyclohexylphenylketone, 2-hydroxymethylphenylpro Examples include a photo-radical polymerization initiator such as bread. These photopolymerization initiators may be used alone or in combination of two or more.
[0047]
Examples of the thermal polymerization initiator include those that decompose by heat to generate an active radical that initiates polymerization and curing, and include, for example, dicumyl peroxide, di-t-butyl peroxide, and t-butyl peroxybenzoyl. , T-butyl hydroperoxide, benzoyl peroxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, paramenthane hydroperoxide, di-t-butyl peroxide and the like. Among them, cumene hydroperoxide, paramenthane hydroperoxide, di-t-butyl peroxide, and the like are preferable because of high thermal decomposition temperature. Among these thermal polymerization initiators, commercially available ones are not particularly limited, but, for example, perbutyl D, perbutyl H, perbutyl P, permentor H (all of these are manufactured by NOF Corporation) and the like are preferable. These thermal polymerization initiators may be used alone or in combination of two or more.
[0048]
When these post-curable pressure-sensitive adhesives contain a hot-melt polymer as a main component, they can be used as hot-melt pressure-sensitive adhesives that exhibit fluidity by heating. When it is increased, it can be used as a soft pressure-sensitive adhesive that exhibits fluidity under pressure.
[0049]
The post-curable pressure-sensitive adhesive, in addition to the above components, as long as the purpose of the present invention is not impaired, for the purpose of adjusting the cohesive force as a pressure-sensitive adhesive, if desired, such as an isocyanate compound, a melamine compound, and an epoxy compound. Various polyfunctional compounds to be compounded in general adhesives may be appropriately compounded. Known additives such as a plasticizer, a resin, a surfactant, a wax, and a fine particle filler can also be added.
[0050]
The curable resin is not particularly limited, and includes, for example, a thermosetting resin, a photocurable resin, and the like. The thermosetting resin is not particularly limited, and examples thereof include an epoxy resin and a polyurethane resin. The photocurable resin is not particularly limited, and examples thereof include an epoxy resin containing a photocationic catalyst such as a photosensitive onium salt and an acrylic resin having a photosensitive vinyl group.
[0051]
It is preferable that these curable resins are not crosslinked. However, when a certain amount of cohesive force is required to form a resin layer, the curable resin may be crosslinked to a required degree.
[0052]
The adhesive resin preferably has a gel fraction of 5% or less. If the gel fraction exceeds 5%, the fluidity when heated or pressurized is poor, and the gap formed in the peripheral portion between the wafer and the support plate may not be sufficiently filled. More preferably, it is 0%.
[0053]
In the method for manufacturing an IC chip of the present invention, first, step 1 of bonding a wafer and a support plate via the double-sided adhesive tape is performed.
At this time, the adhesive resin is caused to flow by heating or pressing at least before or after the lamination or simultaneously with the lamination to fill a gap formed in a peripheral portion between the wafer and the support plate. Note that the order of bonding, heating, and / or pressing is not particularly limited. For example, heating may be performed simultaneously with bonding, or heating may be performed before and after bonding. Further, the pressing may be performed simultaneously with the bonding, or the pressing may be performed before and after the bonding.
[0054]
Examples of the wafer include those made of semiconductors such as silicon and gallium arsenide.
The thickness of the wafer is not particularly limited, but the thinner the wafer, the more easily the damage prevention effect of the present invention can be exhibited, and the thickness after polishing is about 50 μm, for example, a semiconductor wafer having a thickness of 20 to 80 μm. In this case, an excellent breakage prevention effect can be obtained. In addition, a step is formed in the peripheral portion of the wafer so as to reduce the thickness by about 12 to 15 μm in order to hold the wafer when processing or transporting the wafer.
[0055]
The support plate is not particularly limited, but is preferably transparent when the stimulus for generating a gas from the gas generating agent is light. For example, a glass plate; acrylic, olefin, polycarbonate, vinyl chloride, ABS, A plate-like body made of a resin such as polyethylene terephthalate (PET), nylon, urethane, or polyimide may be used.
[0056]
A preferred lower limit of the thickness of the support plate is 500 μm, a preferred upper limit is 3 mm, a more preferred lower limit is 1 mm, and a more preferred upper limit is 2 mm. It is preferable that the variation in the thickness of the support plate is 1% or less.
[0057]
Next, Step 2 of polishing the wafer in a state where the wafer is fixed to the support plate via the double-sided adhesive tape is performed. The polishing method is not particularly limited, and a method used in a normal IC chip manufacturing method can be used.For example, while fixing a support plate, applying cutting water using a polishing wheel that rotates at high speed. A method of polishing a wafer to the thickness of a completed chip is exemplified. In the method for manufacturing an IC chip of the present invention, since the adhesive resin of the double-sided adhesive tape fills the gap formed in the peripheral portion between the wafer and the support plate as described above, water does not enter and uneven polishing occurs. And can be polished well.
[0058]
In the case where the adhesive resin is an uncrosslinked resin that is crosslinked by a stimulus, the method further includes, prior to Step 2, a step of applying a stimulus to the double-sided adhesive tape and crosslinking a part of the adhesive resin that is crosslinked by the stimulus. Is preferred. By cross-linking a part of the adhesive resin, the wafer and the support plate are more firmly fixed, and are not separated in the subsequent polishing step. In addition, by cross-linking, even when the adhesive resin is a hot-melt type adhesive resin, heat resistance is improved, and even when heated by frictional heat in a subsequent polishing step, the resin is fluidized again and the wafer and the support plate are separated. It doesn't even happen.
[0059]
It is preferable that the degree of the cross-linking is limited to such a degree that the wafer and the support plate can be fixed without fluidization. If completely cured, the adhesive strength may be lost and the wafer and the double-sided adhesive tape may be peeled off.
[0060]
Next, in the method for manufacturing an IC chip of the present invention, a step 3 for applying a stimulus to the double-sided adhesive tape and a step 4 for separating the double-sided adhesive tape from the wafer are performed. By applying a stimulus to the double-sided adhesive tape, a gas is generated from the gas generating agent in the resin composition layer and released to the bonding surface between the wafer or the support plate and the double-sided adhesive tape. Since at least a part of the adhesive surface can be peeled off and the adhesive strength of the resin layer can be reduced, the wafer or the support plate bonded to the resin layer containing the gas generating agent can be easily peeled off.
[0061]
When a gas generating agent is contained on the surface of the double-sided adhesive tape bonded to the support plate, a stimulus is given to the support plate and the double-sided adhesive tape before peeling the double-sided adhesive tape from the wafer. By generating gas from the gas generating agent during the period, the adhesive strength is reduced, and the hard support plate is peeled off from the double-sided adhesive tape, so that the double-sided adhesive tape becomes a flexible tape, and the wafer is turned while turning the double-sided adhesive tape Can be peeled off.
[0062]
The method for giving the stimulus is not particularly limited. For example, when a gas generating agent that generates a gas by stimulating with ultraviolet rays is used, a method of irradiating the support plate with ultraviolet rays may be used.
[0063]
In a normal process, a dicing tape is attached to the polished wafer before applying a stimulus to generate gas after the polishing process and peeling the wafer, and thereafter dicing is performed after the wafer is peeled.
[0064]
In the method of manufacturing an IC chip according to the present invention, if necessary, the steps that are usually performed may be omitted, or the order of the steps may be different from the normal order. For example, polishing may be performed after dicing is performed in advance. The process may be performed to make the wafer into chips.
[0065]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.
[0066]
(Example 1)
<Preparation of adhesive>
The following compounds were dissolved in ethyl acetate, and the mixture was polymerized by irradiation with ultraviolet rays to obtain an acrylic copolymer having a weight average molecular weight of 700,000.
[0067]
3.5 parts by weight of 2-isocyanatoethyl methacrylate was added to 100 parts by weight of the resin solid content of the ethyl acetate solution containing the obtained acrylic copolymer to cause a reaction, and further, the resin of the ethyl acetate solution after the reaction was added. For 100 parts by weight of the solid content, 40 parts by weight of pentaerythritol triacrylate and 5 parts by weight of a photopolymerization initiator (Irgacure 651) were mixed to prepare an ethyl acetate solution of the pressure-sensitive adhesive (1).
79 parts by weight of butyl acrylate
15 parts by weight of ethyl acrylate
Acrylic acid 1 part by weight
5 parts by weight of 2-hydroxyethyl acrylate
0.2 parts by weight of photopolymerization initiator
(Irgacure 651, 50% ethyl acetate solution)
Lauryl mercaptan 0.01 parts by weight
30 parts by weight of 2,2'-azobis- (N-butyl-2-methylpropionamide) and 2,4-diethylthioxanthone with respect to 100 parts by weight of the resin solid content of the ethyl acetate solution of the pressure-sensitive adhesive (1) The adhesive (2) containing the gas generating agent was prepared by mixing 3.6 parts by weight.
[0068]
<Preparation of double-sided adhesive tape>
An ethyl acetate solution of the pressure-sensitive adhesive (2) is coated with a 38 μm-thick polyethylene terephthalate (PET) film having both surfaces subjected to corona treatment and embossing, and a dry film having a thickness of about 50 μm on one side not embossed. The solution was dried with a doctor knife and heated at 110 ° C. for 5 minutes to dry the coating solution. The dried pressure-sensitive adhesive layer showed tackiness in a dry state. Next, a PET film subjected to a release treatment was attached to the surface of the pressure-sensitive adhesive (2) layer.
[0069]
An ethyl acetate solution of the pressure-sensitive adhesive (1) is applied on a PET film having a surface subjected to a release treatment so as to have a dry film thickness of about 30 μm with a doctor knife, and heated at 110 ° C. for 5 minutes. The solvent was volatilized to dry the coating solution. The dried pressure-sensitive adhesive layer showed tackiness in a dry state.
[0070]
Next, the surface of the PET film provided with the pressure-sensitive adhesive (2) layer without the pressure-sensitive adhesive (2) layer and the surface of the pressure-sensitive adhesive (1) layer of the PET film provided with the pressure-sensitive adhesive (1) layer are adhered. I matched. Then, it left still at 40 degreeC for 3 days.
[0071]
Thereby, a double-sided pressure-sensitive adhesive tape 1 was provided in which a pressure-sensitive adhesive layer was provided on both sides and the surface of which was protected by a PET film subjected to a release treatment. The pressure-sensitive adhesive layers of the double-sided pressure-sensitive adhesive tape 1 were all transparent.
[0072]
<Manufacture of IC chips>
(Lamination process of silicon wafer and glass plate)
The PET film for protecting the adhesive (2) layer of the double-sided adhesive tape 1 is peeled off, and a circuit of a silicon wafer having a diameter of 20 cm, a thickness of about 750 μm, a surface formed with irregularities of 5 μm, and a peripheral portion of 15 μm is formed. After sticking to the formed surface using a laminator, the double-sided adhesive tape 1 was cut in accordance with the size of the silicon wafer.
[0073]
Next, the PET film protecting the adhesive (1) layer was peeled off, and a glass plate having a diameter of 20.4 cm was attached to the adhesive (1) layer using a vacuum press device. Next, after preheating at 60 ° C. for 2 minutes, 98 ° C./98° C. was applied using a heating press. ² For 1 minute. The double-sided adhesive tape was in close contact with both the wafer and the glass plate, and no gap was observed at the periphery of the wafer.
[0074]
(UV irradiation step)
Irradiation intensity of 365 nm ultraviolet rays on the glass plate surface was 10 mW / cm from the glass plate side using an ultra-high pressure mercury lamp. ² Irradiation was performed for 2 seconds while adjusting the illuminance so that
[0075]
(Polishing process)
A silicon wafer reinforced with a glass plate was attached to a polishing apparatus, and polished until the thickness of the silicon wafer became about 50 μm. At this time, there was no water permeation between the silicon wafer and the double-sided adhesive tape as observed from the glass plate.
[0076]
The silicon wafer was removed from the polishing device, and a dicing tape was stuck on the silicon wafer.
(UV irradiation step)
Irradiation intensity of 365 nm ultraviolet rays on the glass plate surface was 40 mW / cm from the glass plate side using an ultra-high pressure mercury lamp. ² Irradiation was performed for 2 minutes while adjusting the illuminance so that
[0077]
(Wafer peeling process)
The silicon wafer was fixed, and the glass plate was pulled right above and peeled off from the silicon wafer together with the double-sided adhesive tape.
[0078]
(Dicing process)
Subsequently, the silicon wafer reinforced with the dicing tape was attached to a dicing device, and a cutter blade was cut from the wafer side to cut the silicon wafer into a size of an IC chip. Next, the IC chip was peeled off from the dicing tape to take out the IC chip.
[0079]
【The invention's effect】
According to the present invention, there is provided an IC chip manufacturing method capable of preventing breakage or the like of a wafer even if the wafer is extremely thin with a thickness of about 50 μm, improving the handleability, and processing the IC chip satisfactorily without polishing unevenness. Can be provided.

Claims (7)

at least,
A double-sided adhesive tape containing a gas generating agent that generates a gas by stimulation and having a surface made of an adhesive resin showing fluidity by at least one of heating and pressure is formed on one or both sides, and Bonding a wafer having a step to a support plate with a step,
Polishing the wafer while being fixed to the support plate via the double-sided adhesive tape, step 2,
A step 3 of stimulating the double-sided adhesive tape to generate gas from a gas generating agent; and
A method for manufacturing an IC chip, comprising a step 4 of peeling the double-sided adhesive tape from the wafer,
In step 1 for bonding the wafer and the support plate via the double-sided adhesive tape, the adhesive resin is caused to flow by heating or pressing before and after bonding or at the same time as bonding, and the peripheral portion of the wafer and the support plate is bonded. A method for manufacturing an IC chip, characterized by filling gaps generated in the IC chip. Adhesive resin showing fluidity by at least one of heat or pressure is an uncrosslinked resin that is crosslinked by stimulation,
2. The method for manufacturing an IC chip according to claim 1, further comprising, prior to the step 2, a step of applying a stimulus to the double-sided adhesive tape to cross-link a part of the adhesive resin which is cross-linked by the stimulus. 3. The method according to claim 1, wherein the gas generating agent does not exist as particles in the adhesive resin. 4. The method for producing an IC chip according to claim 1, wherein the gas generating agent is an azo compound. The method according to claim 4, wherein the azo compound is an azoamide compound represented by the following formula (1).

In the formula (1), R ¹ and R ² each represent the same or different lower alkyl groups, and R ³ represents a saturated alkyl group having 2 or more carbon atoms. 4. The method for producing an IC chip according to claim 1, wherein the gas generating agent is an azide compound. 7. The method for producing an IC chip according to claim 1, wherein the gas generating agent is contained only in a surface portion of the adhesive resin.