JP4478268B2 - Thin film device manufacturing method - Google Patents

Description

一次、二次転写体１８０，２００の構成材料としては、両者に硬さの差があれば、各種合成樹脂または各種ガラス材が挙げられ、特に、各種合成樹脂や通常の（低融点の）安価なガラス材が好ましく、これらの材料から一次転写体１８０が二次転写体２００より硬くなる組合せを選択すべきである。
【００７２】
合成樹脂としては、熱可塑性樹脂、熱硬化性樹脂のいずれでもよく、例えば、ポリエチレン、ポロプロピレン、エチレン−プレピレン共重合体、エチレン−酢酸ビニル共重合体（ＥＶＡ）等のポリオレフィン、環状ポリオレフィン、変性ポリオレフィン、ポリ塩化ビニル、ポリ塩化ビニリデン、ポリスチレン、ポリアミド、ポリイミド、ポリアミドイミド、ポリカーボネート、ポリ−（４−メチルベンテン−１）、アイオノマー、アクリル系樹脂、ポリメチルメタクリレート、アクリル−スチレン共重合体（ＡＳ樹脂）、ブタジエン−スチレン共重合体、ポリオ共重合体（ＥＶＯＨ）、ポリエチレンテレフタレート（ＰＥＴ）、ポリプチレンテレフタレート（ＰＢＴ）、プリシクロヘキサンテレフタレート（ＰＣＴ）等のポリエステル、ポリエーテル、ポリエーテルケトン（ＰＥＫ）、ポリエーテルエーテルケトン（ＰＥＥＫ）、ポリエーテルイミド、ポリアセタール（ＰＯＭ）、ポリフェニレンオキシド、変性ポリフェニレンオキシド、ポリアリレート、芳香族ポリエステル（液晶ポリマー）、ポリテトラフルオロエチレン、ポリフッ化ビニリデン、その他フッ素系樹脂、スチレン系、ポリオレフィン系、ポリ塩化ビニル系、ポリウレタン系、フッ素ゴム系、塩素化ポリエチレン系等の各種熱可塑性エラストマー、エボキシ樹脂、フェノール樹脂、ユリア樹脂、メラミン樹脂、不飽和ポリエステル、シリコーン樹脂、ポリウレタン等、またはこれらを主とする共重合体、ブレンド体、ポリマーアロイ等が挙げられ、これらのうちの１種または２種以上を組み合わせて（例えば２層以上の積層体として）用いることができる。
【００７３】
ガラス材としては、例えば、ケイ酸ガラス（石英ガラス）、ケイ酸アルカリガラス、ソーダ石灰ガラス、カリ石灰ガラス、鉛（アルカリ）ガラス、バリウムガラス、ホウケイ酸ガラス等が挙げられる。このうち、ケイ酸ガラス以外のものは、ケイ酸ガラスに比べて融点が低く、また、成形、加工も比較的容易であり、しかも安価であり、好ましい。
【００７４】
二次転写体２００として合成樹脂で構成されたものを用いる場合には、大型の二次転写体２００を一体的に成形することができるとともに、湾曲面や凹凸を有するもの等の複雑な形状であっても容易に製造することができ、また、材料コスト、製造コストも安価であるという種々の利点が享受できる。したがって、合成樹脂の使用は、大型で安価なデバイス（例えば、液晶ディスプレイ）を製造する上で有利である。
【００７５】
なお、二次転写体２００は、例えば、液晶セルのように、それ自体独立したデバイスを構成するものや、例えばカラーフィルター、電極層、誘電体層、絶縁層、半導体素子のように、デバイスの一部を構成するものであってもよい。
【００７６】
さらに、一次、二次転写体１８０，２００は、金属、セラミックス、石材、木材紙等の物質であってもよいし、ある品物を構成する任意の面上（時計の面上、エアコンの表面上、プリント基板の上等）、さらには壁、柱、天井、窓ガラス等の構造物の表面上であってもよい。
【００７７】
次に、図８に示すように、一次転写体、被転写層、及び二次転写体を備えた転写後構造物を特定溶剤に浸すことによって、一次転写体を溶剤に溶かしながら分離層１６０において被転写層を一次転写体から剥離する。第２分離層１６０として上述した水溶性接着剤を用いた場合には、少なくとも第２分離層１６０を含む領域を純水に浸せばよい。
【００７８】
最後に、薄膜デバイス層１４０の表面に付着した第２分離層１６０を除去することで、図９に示すように、二次転写体２００に転写された薄膜デバイス層１４０を得ることができる。ここで、この二次転写体２００に対する薄膜デバイス層１４０の積層関係は、図２に示すように当初の基板１００に対する薄膜デバイス層１４０の積層関係と同じとなる。
【００７９】
以上のような各工程を経て、被転写層（薄膜デバイス層）１４０の二次転写体２００への転写が完了する。その後、被転写層（薄膜デバイス層）１４０に隣接するＳｉＯ₂膜の除去や、被転写層１４０上への配線等の導電層や所望の保護膜の形成等を行うこともできる。
【００８０】
本発明では、被剥離物である被転写層（薄膜デバイス層）１４０自体を直接に剥離するのではなく、第１分離層１２０及び第２分離層１６０において分離して二次転写体２００に転写するため、被分離物（被転写層１４０）の特性、条件等にかかわらず、容易かつ確実に、しかも均一に転写することができ、分離操作に伴う被分離物（被転写層１４０）へのダメージもなく、被転写層１４０の高い信頼性を維持することができる。
【００８１】
次に、図２〜図９の具体的な製造プロセスの例を図１１〜図２１を用いて説明する。
（工程１）
図１１に示すように、基板（例えば石英基板）１００上に、第１分離層（例えば、ＬＰＣＶＤ法により形成されたアモルファスシリコン層））１２０と、中間層（例えば、ＳｉＯ₂膜）１４２と、アモルファスシリコン層（例えばＬＰＣＶＤ法により形成される）１４３とを順次に積層形成し、続いて、アモルファスシリコン層１４３の全面に上方からレーザー光を照射し、アニールを施す。これにより、アモルファスシリコン層１４３は再結晶化してポリシリコン層となる。
（工程２）
続いて、図１２に示すように、レーザーアニールにより得られたポリシリコン層をパターニングして、アイランド１４４ａ，１４４ｂを形成する。
（工程３）
図１３に示されるように、ＣＶＤ法により、アイランド１４４ａ，１４４ｂを含む全面をゲート絶縁膜１４８によって覆う。
（工程４）
図１４に示されるように、ポリシリコンあるいはメタル等からなるゲート電極１５０ａ，１５０ｂを形成する。
（工程５）
図１５に示すように、ポリイミド等からなるマスク層１７０を形成し、ゲート電極１５０ｂおよびマスク層１７０をマスクとして用い、セルフアラインで、例えばボロン（Ｂ）のイオン注入を行う。これによって、ｐ+層１７２ａ，１７２ｂが形成される。
（工程６）
図１６に示すように、ポリイミド等からなるマスク層１７４を形成し、ゲート電極１５０ａおよびマスク層１７４をマスクとして用い、セルフアラインで、例えばリン（Ｐ）のイオン注入を行う。これによって、ｎ+層１４６ａ，１４６ｂが形成される。
（工程７）
図１７に示すように、層間絶縁膜１５４を形成し、選択的にコンタクトホール形成後、電極１５２ａ〜１５２ｄを形成する。
【００８２】
このようにして形成されたＣＭＯＳ構造のＴＦＴが、図２〜図９における被転写層（薄膜デバイス層）１４０に該当する。なお、層間絶縁膜１５４上に保護膜を形成してもよい。
（工程８）
図１８に示すように、ＣＭＯＳ構成のＴＦＴ上に、第２分離層としての熱溶融性接着層１６０を形成する。このとき、ＴＦＴの表層に生じていた段差が、熱溶融性接着剤１６０により平坦化される。なお、第２分離層は、第１分離層と同様にアブレーション層で構成することもでき、あるいは水溶性接着剤を用いることもできる。
【００８３】
ここで、薄膜デバイスであるＴＦＴ上にまず絶縁層などの保護層を形成し、その保護層上に第２分離層を設けることが好ましい。特に、第２分離層をアブレーション層とした場合に、アブレーション時に保護層により薄膜デバイス層を保護することができる。
【００８４】
また、特に第２分離層をアブレーション層にて形成する場合には、その第２分離層自体を第１分離層と同様に多層にて形成することもできる。さらに、この第２分離層と薄膜デバイス層との間に、金属層等の遮光層を設けるとさらに良い。アブレーション時に、薄膜デバイス層に光が入射することを防止できるからである。
【００８５】
この第２分離層形成後に、第２分離層である熱溶融性接着層１６０を介して、ＴＦＴを一次転写体（例えば、ソーダガラス基板）１８０に貼り付ける。
（工程９）
図１９に示すように、基板１００の裏面から、例えば、Ｘｅ−Ｃｌエキシマレーザー光を照射する。これにより、第１分離層１２０の層内および／または界面において剥離を生じせしめる。
（工程１０）
図２０に示すように、基板１００を引き剥がす。
（工程１１）
さらに、第１分離層１２０をエッチングにより除去する。これにより、図２１に示すように、ＣＭＯＳ構成のＴＦＴが、一次転写体１８０に転写されたことになる。
（工程１２）
次に、図２２に示すように、ＣＭＯＳ構成のＴＦＴの下面に、熱溶融性樹脂層１６０よりも硬化点が低い接着層として、例えばエポキシ樹脂層１９０を形成する。次に、そのエポキシ樹脂層１９０を介して、ＴＦＴを合成樹脂からなる二次転写体２００に貼り付ける。続いて、熱を加えてエポキシ樹脂層１９０を硬化させ、二次転写体２００とＴＦＴとを接着（接合）する。
（工程１３）
次に、図２３に示すように例えばオーブン２１０を用いて熱溶融性樹脂層１６０を熱により溶融させ、この熱溶融性樹脂層１６０を境にして、ＴＦＴを一次転写体１８０より引き剥がす。さらに、ＴＦＴの下面に残存している熱溶融性樹脂層１６０を、例えばキシレンなどにより除去する。これにより、図２４に示すように、ＴＦＴが二次転写体２００に転写される。この図２４の状態は、図１７に示す基板１００及び第１分離層１２０を、二次転写体２００及び接着層１９０に置き換えたものと同じとなる。従って、ＴＦＴの製造工程に用いた基板１００に対する積層関係が、二次転写体２００上にて確保される。このため、電極１５２ａ〜１５２ｄが露出され、それへのコンタクトあるいは配線を容易に行うことができる。なお、図２４の状態とした後に、その表層に保護層を形成しても良い。
【００８６】
図２５は本発明に係る薄膜デバイスの転写方法の第２の実施の形態を示す図であり、第１の実施の形態における工程８（図８）に対応した図である。
【００８７】
図２５において、一次転写体１８０上に第２分離層１６０、薄膜デバイス層１４０、接着層１９０、二次転写体２００が形成された状態において、一次転写体１８０を溶剤によって溶融除去する。この溶融除去を可能とするための、一次転写体１８０、二次転写体２００の材料、および二次転写時の溶剤の組合せ例は既述の表に示すとおりである。なお一次転写体１８０を溶融除去する場合には第２分離層１６０を省略することも可能である。
【００８８】
第１実施形態の一次転写体剥離は、一次転写体の面積が大きくなると剥離が容易でなくなるが、第２実施形態のように溶融除去ではこのような問題はない。
【００８９】
【実施例】
次に、本発明の具体的実施例について説明する。
（実施例１）
縦５０mm×横５０mm×厚さ１．１mmの石英基板（軟化点：１６３０℃、歪点：１０７０℃、エキシマレーザの透過率：ほぼ１００％）を用意し、この石英基板の片面に、第１分離層（レーザ光吸収層）として非晶質シリコン（ａ−Ｓｉ）膜を低圧ＣＶＤ法（Ｓｉ_２ Ｈ₆ ガス、４２５℃）により形成した。第１分離層の膜厚は、１００nmであった。
【００９０】
次に、第１分離層上に、中間層としてＳｉＯ₂ 膜を形成した。このＳｉＯ₂ 膜の形成に液相プロセスを用いた。すなわち、東燃株式会社のポリシラザン（商品名）をキシレンに混合して、基板上にスピン塗布し、この塗布膜を、水蒸気を含む雰囲気で熱処理することでＳｉＯ₂膜に転化させた。この中間層の膜厚は、２００nmであった。
【００９１】
次に、中間層上に、被転写層として膜厚５０nmの非晶質シリコン膜を低圧ＣＶＤ法（Ｓｉ₂ Ｈ₆ ガス、４２５℃）により形成し、この非晶質シリコン膜にレーザ光（波長３０８nm）を照射して、結晶化させ、ポリシリコン膜とした。その後、このポリシリコン膜に対し、所定のパターンニングを施し、薄膜トランジスタのソース・ドレイン・チャネルとなる領域を形成した。この後、中間層ＳｉＯ₂と同様の液相プロセスを用いて上記ポリシラザンからなるゲート絶縁膜ＳｉＯ₂を形成した。その後、ゲート絶縁膜上にゲート電極を液相プロセスにて形成した。このために、旭電化工業株式会社製の商品名：アデカＩＴＯ塗布膜／ＩＴＯ−１０３Ｌを液状とした塗布液をスピンコートし、これを上述の第１，第２の熱処理部６０３Ａ，６０３Ｂにて熱処理して塗布ＩＴＯ膜を形成した。
その後、塗布ＩＴＯ膜上に金属メッキ層を形成した。そして、塗布ＩＴＯ膜及び金属メッキ層をパターニングしてゲート電極を形成した。このゲート電極をマスクとしてイオン注入することによって、自己整合的（セルファライン）にソース・ドレイン領域を形成し、薄膜トランジスタを形成した。この後、必要に応じて、ソース・ドレイン領域に接続される電極及び配線、ゲート電極につながる配線が形成される。これらの電極や配線も、ゲート電極と同様にして同一材料により液相プロセスを用いて形成した。
【００９２】
次に、前記薄膜トランジスタの上に、アセトン溶解性接着剤を塗布し、一次転写体として縦２００mm×横３００mm×厚さ１．１mmの大型の透明な塩化ビニル樹脂基板を接合した。
【００９３】
次に、Ｘｅ−Ｃｌエキシマレーザ（波長：３０８nm）を石英基板側から照射し、第１分離層に剥離（層内剥離および界面剥離）を生じさせた。照射したＸｅ−Ｃｌエキシマレーザのエネルギー密度は、２５０mJ/cm²、照射時間は、２０nsecであった。なお、エキシマレーザの照射は、スポットビーム照射とラインビーム照射とがあり、スポットビーム照射の場合は、所定の単位領域（例えば８mm×８mm）にスポット照射し、このスポット照射を単位領域の１／１０程度ずつずらしながら照射していく。また、ラインビーム照射の場合は、所定の単位領域（例えば３７８mm×０．１mmや３７８mm×０．３mm（これらはエネルギーの９０％以上が得られる領域））を同じく１／１０程度ずつずらしながら照射していく。これにより、第１分離層の各点は少なくとも１０回の照射を受ける。このレーザ照射は、石英基板全面に対して、照射領域をずらしながら実施される。
【００９４】
この後、石英基板と一次転写体とを第１分離層において引き剥がし、石英基板上に形成された薄膜トランジスタおよび中間層を、一次転写体に一次転写した。
【００９５】
その後、中間層の表面に付着した第１分離層を、エッチングや洗浄またはそれらの組み合わせにより除去した。また、石英基板についても同様の処理を行い、再使用に供した。
【００９６】
さらに、露出した中間層の下面に、紫外線硬化型接着剤を塗布し（膜厚：１００μm ）、さらにその塗膜に、二次転写体として縦２００mm×横３００mm×厚さ１．１mmの大型の透明なフッ素樹脂基板を接合した後、紫外線を照射して接着剤を硬化させ、これらを接着固定した。
【００９７】
その後、アセトンに浸して、一次転写体を除去した。これにより、薄膜トランジスタおよび中間層を、二次転写体であるフッ素樹脂基板側に二次転写した。なお、一次転写体の硬度は二次転写体の硬度より高くなるように、両者の厚さに差を設けた。
【００９８】
ここで、一次転写体が石英基板より大きな基板であれば、本実施例のような石英基板からの一次転写を、平面的に異なる領域に繰り返して実施し、一次転写体上に、石英基板に形成可能な薄膜トランジスタの数より多くの薄膜トランジスタを形成することができる。さらに、一次転写体上に繰り返し積層し、同様により多くの薄膜トランジスタを形成することができる。あるいは、二次転写体となる基板を、一次転写体及び石英基板よりも大型基板とし、二次転写を繰り返し実施して、石英基板に形成可能な薄膜トランジスタの数より多くの薄膜トランジスタを形成することもできる。
【００９９】
【発明の効果】
以上述べたように、本発明によれば、２度転写技術を利用した薄膜デバイスの転写・製造方法において、第２の転写基板に優先させて第１の転写基板から被転写層を剥離又は分離することができる薄膜デバイスの転写・分離技術を提供することができる。
【０１００】
さらに、本発明によれば、２度転写技術において、剥離層で転写体が被転写層から十分に剥離可能な薄膜デバイスの転写・分離技術を提供することができる。
【図面の簡単な説明】
【図１】本発明の薄膜デバイスの製造方法の第１の実施の形態における第１の工程を示す断面図である。
【図２】本発明の薄膜デバイスの製造方法の第１の実施の形態における第２の工程を示す断面図である。
【図３】本発明の薄膜デバイスの製造方法の第１の実施の形態における第３の工程を示す断面図である。
【図４】本発明の薄膜デバイスの製造方法の第１の実施の形態における第４の工程を示す断面図である。
【図５】本発明の薄膜デバイスの製造方法の第１の実施の形態における第５の工程を示す断面図である。
【図６】本発明の薄膜デバイスの製造方法の第１の実施の形態における第６の工程を示す断面図である。
【図７】本発明の薄膜デバイスの製造方法の第１の実施の形態における第７の工程を示す断面図である。
【図８】本発明の薄膜デバイスの製造方法の第１の実施の形態における第８の工程を示す断面図である。
【図９】本発明の薄膜デバイスの製造方法の第１の実施の形態における第９の工程を示す断面図である。
【図１０】第１の基板（図１の基板１００）のレーザー光の波長に対する透過率の変化を示す図である。
【図１１】図２の薄膜デバイスを形成するための第１の工程を示す断面図である。
【図１２】図２の薄膜デバイスを形成するための第２の実施の形態における第２の工程を示す断面図である。
【図１３】図２の薄膜デバイスを形成するための第３の工程を示す断面図である。
【図１４】図２の薄膜デバイスを形成するための第４の工程を示す断面図である。
【図１５】図２の薄膜デバイスを形成するための第５の工程を示す断面図である。
【図１６】図２の薄膜デバイスを形成するための第６の工程を示す断面図である。
【図１７】図２の薄膜デバイスを形成するための第７の工程を示す断面図である。
【図１８】図３の工程を具体的構造にて説明する第８の工程の断面図である。
【図１９】図４の工程を具体的構造にて説明する第９の工程の断面図である。
【図２０】図５の工程を具体的構造にて説明する第１０の工程の断面図である。
【図２１】図６の工程を具体的構造にて説明する第１１の工程の断面図である。
【図２２】図７の工程を具体的構造にて説明する第１２の工程の断面図である。
【図２３】図８の工程を具体的構造にて説明する第１３の工程の断面図である。
【図２４】図９の工程を具体的構造にて説明する第１４の工程の断面図である。
【図２５】本発明の第２の実施の形態に係る薄膜デバイスの製造方法における二次転写（第一実施形態の工程８（図８）に対応）の状態を示す断面図である。[0001]
[Industrial application fields]
The present invention relates to a transfer technique in which a thin film device (thin film semiconductor circuit) formed on a substrate is transferred to a transfer substrate.
[Prior art]
For example, when manufacturing a liquid crystal display using a thin film transistor (TFT), a process of forming a thin film transistor on a substrate by CVD or the like is performed. Since the process of forming the thin film transistor on the substrate involves a high temperature treatment, the substrate must be made of a material having excellent heat resistance, that is, a material having a high softening point and a high melting point. Therefore, at present, quartz glass is used as a substrate that can withstand a temperature of about 1000 ° C., and heat-resistant glass is used as a substrate that can withstand a temperature of around 500 ° C.
[0002]
As described above, the substrate on which the thin film devices are mounted must satisfy the conditions for manufacturing those thin film devices. That is, the substrate to be used is determined so as to satisfy the manufacturing conditions of the mounted device.
[0003]
However, when attention is paid only to the stage after the completion of the substrate on which the thin film device such as TFT is mounted, the above-mentioned “substrate” may not always be preferable.
[0004]
For example, as described above, a quartz substrate, a heat-resistant glass substrate, or the like is used when a manufacturing process involving high-temperature processing is performed, but these are very expensive, and thus increase the product price.
[0005]
Further, the glass substrate is heavy and has a property of being easily broken. In liquid crystal displays used in portable electronic devices such as palmtop computers and mobile phones, it is desirable to be as cheap as possible, light, to withstand some deformation, and not to break even when dropped. The glass substrate is usually heavy, weak against deformation, and may be destroyed by dropping.
[0006]
In other words, there is a groove between the constraints resulting from the manufacturing conditions and the desirable characteristics required for the product, and it has been extremely difficult to satisfy both conditions and characteristics.
[0007]
Therefore, the present applicant has proposed a technique in which a transfer layer including a thin film device is formed on a substrate by a conventional process, and then the transfer layer including the thin film device is detached from the substrate and transferred to a transfer body. (Japanese Patent Application No. 8-225643).
[0008]
For this purpose, a separation layer is formed between the substrate and the thin film device as the transfer layer. By irradiating this separation layer with light, it is possible to release the layer to be transferred from the substrate by peeling off the inside and / or interface of the separation layer and weakening the bonding force between the substrate and the layer to be transferred. It is said. As a result, the transferred layer is transferred to the transfer body. Here, a quartz substrate, a heat-resistant glass substrate, or the like is used when a manufacturing process involving high-temperature processing is performed to form a thin film device. However, since the transfer body is not exposed to such a high temperature treatment, there is an advantage that the restrictions required for the transfer body are greatly relaxed.
[0009]
In the transfer technique described here, the first substrate (original substrate) used for manufacturing the layer to be transferred is laminated and the first transfer substrate (primary first transfer body) that is the transfer destination of the layer to be transferred is used. This is opposite to the stacking relationship.
[0010]
Therefore, the transfer layer transferred to the first transfer substrate is retransferred to the second transfer substrate (secondary transfer body) to restore the layered relationship of the transfer layers. Furthermore, when transferring only once, it is difficult to transfer the transferred layer on the quartz substrate to the film (primary transfer body) suddenly, but secondary transfer through primary transfer is used. By doing so, it becomes possible to suitably transfer the transfer layer to the film-like secondary transfer member.
[0011]
[Problems to be solved by the invention]
By the way, there are the following problems in the conventional technique in which the transfer is performed twice. First, when performing the first transfer, there is a point to be improved in peeling or separating the transferred layer from the original substrate. Further, in the conventional double transfer technology, the transfer layer and the first transfer substrate are bonded via a water-soluble adhesive, and this adhesive / separation layer is exposed by exposing the water-soluble adhesive to an aqueous solvent. The transfer layer is peeled off from the primary transfer body by this water-soluble adhesive and transferred to the secondary transfer body. However, this peeling is not sufficient or takes time to peel off. There is a problem.
[0012]
Accordingly, an object of the present invention is to easily transfer a layer to be transferred from an original substrate when performing a first transfer in order to solve the above-described problems in a conventional thin film device transfer / manufacturing method using a double transfer technology. It is an object of the present invention to provide a transfer / separation technique for a thin film device that can be separated or separated.
[0013]
Another object of the present invention is to provide a transfer / separation technique for a thin film device in which the transfer layer can be easily peeled off from the first transfer substrate in the twice transfer technique.
[0014]
[Means for Solving the Problems]
A method of manufacturing a thin film device according to the present invention includes a first step of forming a first separation layer on an original substrate, and a thin film transistor including a plurality of thin films on the first separation layer and including a source electrode and a drain electrode. A second step of forming a transfer layer, a third step of bonding a first transfer substrate on the transfer layer, and peeling off the transfer layer from the original substrate with the first separation layer as a boundary A fourth step of bonding, a fifth step of bonding a second transfer substrate to the lower side of the layer to be transferred, and peeling the first transfer substrate from the first transfer substrate while dissolving and removing the first transfer substrate in a specific solvent. And a sixth step of transferring the transferred layer to the second transfer substrate, wherein the material of the first transfer substrate is acrylic resin, and the material of the second transfer substrate is polyethylene And the solvent is IPA.
As a result, the entire first transfer substrate is dissolved in the solvent in the sixth step, so that the layer to be transferred can be reliably peeled from the first transfer substrate.
[0015]
The thin film device manufacturing method according to the present invention includes a first step of forming a first separation layer on an original substrate, and a thin film transistor including a plurality of thin films on the first separation layer and including a source electrode and a drain electrode. A second step of forming a transfer layer including: a third step of bonding a first transfer substrate onto the transfer layer; and the transfer substrate as the original substrate with the first separation layer as a boundary. A fourth step of peeling off the first transfer substrate, a fifth step of bonding a second transfer substrate to the lower side of the layer to be transferred, and the first transfer substrate while dissolving and removing the first transfer substrate in a specific solvent. And a sixth step of transferring the transferred layer to the second transfer substrate, and the material of the first transfer substrate is vinyl chloride resin or polyethersulfone, and the second step The material of the transfer substrate is a fluororesin, and the solvent is aceto It is characterized in that it.
As a result, the entire first transfer substrate is dissolved in the solvent in the sixth step, so that the layer to be transferred can be reliably peeled from the first transfer substrate.
[0016]
Further, it is desirable that the first transfer substrate is selected from those harder than the second transfer substrate.
When the layer to be transferred is peeled from the original substrate, the first transfer substrate is formed of a hard material and form so that the peeling can be easily performed.
Further, by using a liquid phase process in which the plurality of thin films constituting the thin film device and at least one thin film of the first and second separation layers are solidified after the liquid containing the constituent components of the thin film is applied. You may make it form.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings. 1 to 9 are diagrams for explaining a first embodiment (a transfer method of a thin film device) of the present invention. The first embodiment relates to a method of transferring a transfer layer composed of a thin film device layer twice and transferring it to a transfer body. Of the film forming methods for each film, the liquid phase process will be described separately for each type of film.
[0018]
As shown in FIG. 1, a first separation layer (light absorption layer) 120 is formed on a substrate 100. Hereinafter, the substrate 100 and the first separation layer 120 will be described. The substrate 100 preferably has a light-transmitting property that allows light to pass therethrough. In this case, the light transmittance is preferably 10% or more, and more preferably 50% or more. If this transmittance is too low, the attenuation (loss) of light increases, and a larger amount of light is required to peel off the first separation layer 120.
[0019]
Further, the substrate 100 is preferably made of a highly reliable material. When all the films constituting the transferred layer 140 formed on the substrate 100 are implemented by a liquid phase process, heat resistance is not required.
[0020]
However, the substrate 100 is preferably made of a material having a strain point equal to or higher than Tmax, where Tmax is the maximum temperature when the transfer layer 140 is formed. In the case where a part of the transferred layer 140 is formed by a relatively high temperature process other than the liquid layer process, the constituent material of the substrate 100 preferably has a strain point of 350 ° C. or higher, and has a temperature of 500 ° C. or higher. Is more preferable. As such a thing, heat resistant glass, such as quartz glass, Corning 7059, Nippon Electric Glass OA-2, is mentioned, for example.
[0021]
Further, the thickness of the substrate 100 is not particularly limited, but is usually preferably about 0.1 to 5.0 mm, and more preferably about 0.5 to 1.5 mm. If the thickness of the substrate 100 is too thin, the strength is reduced, and if it is too thick, light attenuation tends to occur when the transmittance of the substrate 100 is low. When the light transmittance of the substrate 100 is high, the thickness thereof may exceed the upper limit value. Note that the thickness of the substrate 100 is preferably uniform so that light can be uniformly irradiated.
[0022]
The first separation layer 120 receives one or more of a physical action (light, heat, etc.), a chemical action (chemical reaction with a chemical solution, etc.) or a mechanical action (tensile force, vibration). Thus, the bonding force is reduced or eliminated, thereby promoting the separation of the substrate 100 through the first separation layer 120.
[0023]
For example, the first separation layer 120 has such a property that it absorbs irradiated light and causes peeling (hereinafter referred to as “in-layer peeling” or “interfacial peeling”) in the layer and / or the interface. Preferably, the bonding force between the atoms or molecules of the substance constituting the first separation layer 120 disappears or decreases due to light irradiation, that is, ablation occurs, resulting in delamination and / or interfacial delamination. The one that leads to is good.
[0024]
Furthermore, the gas may be emitted from the first separation layer 120 by light irradiation, and the separation effect may be exhibited. That is, when the component contained in the first separation layer 120 is released as a gas, and when the first separation layer 120 absorbs light and becomes a gas for a moment, its vapor is released and contributes to the separation. There are cases. Examples of the composition of the first separation layer 120 include those described in the following A to E.
A. Amorphous silicon (a-Si)
This amorphous silicon may contain hydrogen (H). In this case, the content of H is preferably about 2 atomic% or more, and more preferably about 2 to 20 atomic%. Thus, when a predetermined amount of hydrogen (H) is contained, hydrogen is released by light irradiation, and an internal pressure is generated in the first separation layer 120, which becomes a force for peeling the upper and lower thin films. The content of hydrogen (H) in the amorphous silicon is adjusted by appropriately setting film forming conditions such as gas composition, gas pressure, gas atmosphere, gas flow rate, temperature, substrate temperature, and input power in CVD. be able to.
B. Various oxide ceramics such as silicon oxide or silicate compound, titanium oxide or titanate compound, zirconium oxide or zirconate compound, lanthanum oxide or lanthanum oxide compound, electrical conductor (ferroelectric) or semiconductor
Examples of silicon oxide include SiO and SiO. ₂ , Si _Three O ₂ Examples of silicic acid compounds include K ₂ SiO _Three , Li ₂ SiO _Three , CaSiO _Three , ZrSiO _Four , Na ₂ SiO _Three Is mentioned.
[0025]
As titanium oxide, TiO, Ti ₂ 0 _Three , Ti0 ₂ Examples of titanic acid compounds include BaTi0 _Four , BaTiO _Three , Ba ₂ Ti ₉ O ₂₀ , BaTi _Five O ₁₁ , CaTiO _Three , SrTiO _Three , PbTiO _Three , MgTiO _Three , ZrTiO ₂ , SnTiO _Four , Al ₂ TiO _Five , FeTiO _Three Is mentioned.
[0026]
As zirconium oxide, ZrO ₂ As the zirconic acid compound, for example, BaZrO _Three , ZrSiO _Four , PbZrO _Three MgZrO _Three , K ₂ ZrO _Three Is mentioned.
C. Ceramics or dielectrics such as PZT, PLZT, PLLZT, PBZT (ferroelectric)
D. Nitride ceramics such as silicon nitride, aluminum nitride, titanium nitride
E. Organic polymer materials
Organic polymer materials include -CH-, -CO- (ketone), -CONH- (amide), -NH- (imide), -COO- (ester), -N = N- (azo), -CH Any of those having a bond such as ═N- (shiff) (these bonds are cut by light irradiation), particularly those having many of these bonds may be used. The organic polymer material may have an aromatic hydrocarbon (one or more benzene rings or condensed rings thereof) in the structural formula.
[0027]
Specific examples of such organic polymer materials include polyolefins such as polyethylene and polypropylene, polyimide, polyamide, polyester, polymethyl methacrylate (PMMA), polyphenylene sulfide (PPS), polyethersulfone (PES), epoxy resin, and the like. Can be given.
F. metal
Examples of the metal include Al, Li, Ti, Mn, In, Sn, Y, La, Ce, Nd, Pr, Gd, Sm, or an alloy containing at least one of them.
[0028]
The thickness of the first separation layer 120 varies depending on various conditions such as the purpose of peeling, the composition of the first separation layer 120, the layer structure, and the formation method, but it is usually preferably about 1 nm to 20 μm. It is more preferably about ˜2 μm, and further preferably about 40 nm to 1 μm. If the thickness of the first separation layer 120 is too small, the uniformity of film formation may be impaired and peeling may be uneven. If the film thickness is too thick, the good separation of the first separation layer 120 is obtained. In order to ensure the above, it is necessary to increase the light power (light amount), and it takes time to remove the first separation layer 120 later. Note that the thickness of the first separation layer 120 is preferably as uniform as possible.
[0029]
The formation method of the 1st separated layer 120 is not specifically limited, According to various conditions, such as a film | membrane composition and a film thickness, it selects suitably. For example, CVD (including MOCVD, low pressure CVD, ECR-CVD), vapor deposition, molecular beam vapor deposition (MB), sputtering, ion plating, PVD and other various vapor deposition methods, electroplating, immersion plating (dipping), Various plating methods such as electroless plating, Langmuir Projet (LB) method, spin coating, spray coating, roll coating and other coating methods, various printing methods, transfer methods, ink jet methods, powder jet methods, etc. Two or more of them can be combined to form. The liquid phase process will be described later.
[0030]
For example, when the composition of the first separation layer 120 is amorphous silicon (a-Si), it can be formed by CVD, particularly low-pressure CVD or plasma CVD.
[0031]
Next, as shown in FIG. 2, a transfer layer (thin film device layer) 140 is formed on the first separation layer 120.
[0032]
An enlarged cross-sectional view of a portion K of the thin film device layer 140 (a portion surrounded by a one-dot chain line in FIG. 2) is shown on the right side of FIG. As shown, the thin film device layer 140 may be, for example, SiO 2 ₂ The TFT includes a TFT (thin film transistor) formed on the film (intermediate layer) 142. The TFT includes a source / drain layer 146 formed by introducing an n-type impurity into the polysilicon layer, a channel layer 144, A gate insulating film 148, a gate electrode 150, an interlayer insulating film 154, and an electrode 152 made of, for example, aluminum.
[0033]
In the present embodiment, SiO as an intermediate layer provided in contact with the first separation layer 120 ₂ The film is used, but Si _Three N _Four Other insulating films such as can also be used. Si0 ₂ The thickness of the film (intermediate layer) is appropriately determined according to the purpose of formation and the degree of function that can be exhibited. Usually, it is preferably about 10 nm to 5 μm, more preferably about 40 nm to 1 μm. preferable. The intermediate layer is formed for various purposes, for example, a protective layer that physically or chemically protects the transferred layer 140, an insulating layer, a conductive layer, a laser light shielding layer, a migration-preventing barrier layer, or a reflective layer. That exhibit at least one of these functions.
[0034]
In some cases, Si0 ₂ The transferred layer (thin film device layer) 140 may be formed directly on the first separation layer 120 without forming an intermediate layer such as a film.
[0035]
The transferred layer 140 (thin film device layer) is a layer including a thin film device such as a TFT as shown on the right side of FIG.
[0036]
As the thin film device, in addition to the TFT, for example, a thin film diode, a photoelectric conversion element (photosensor, solar cell) or a silicon resistance element composed of a silicon PIN junction, other thin film semiconductor devices, electrodes (eg, ITO, mesa) Transparent electrodes such as films), actuators such as switching elements, memories, piezoelectric elements, micromirrors (piezo thin film ceramics), magnetic recording thin film heads, coils, inductors, thin film highly magnetically permeable materials, and micromagnetic devices combining them, There are filters, reflective films, dichroic mirrors, etc. The present invention is not limited to the above examples, and can be applied to various thin film devices that do not contradict the gist of the present invention.
[0037]
Such a thin film device is usually formed through a relatively high process temperature in relation to its formation method. Therefore, in this case, as described above, the substrate 100 needs to have a high reliability that can withstand the process temperature.
[0038]
Next, as shown in FIG. 3, for example, a hot-melt adhesive layer 160 is formed on the thin film device layer 140 as a second separation layer. In addition, the 2nd separated layer can also be comprised with an ablation layer similarly to the 1st separated layer. Further, in the case of once transfer, this second separation layer is unnecessary.
[0039]
Examples of the heat-meltable adhesive layer 160 include electron waxes such as proof wax (trade name) that are less likely to contaminate thin film devices with impurities (sodium, potassium, etc.).
[0040]
Note that this type of heat-meltable adhesive layer 160 can be formed by a coating method which is a liquid phase process, for example, a spin coating method.
[0041]
A water-soluble adhesive can also be used as the second separation layer. Examples of this type of water-soluble adhesive include Chemi-Seal U-451D (trade name) manufactured by Chemitech Co., Ltd., and 3Bond 3046 (trade name) manufactured by ThreeBond Co., Ltd.
[0042]
Thus, since the second separation layer 160 does not exist when the thin film device layer 140 is formed, there are fewer restrictions than the material of the first separation layer 120, and heat resistance is not required.
[0043]
Further, as shown in FIG. 3, a primary transfer body (first transfer substrate) 180 is bonded onto, for example, an adhesive layer 160 that is a second separation layer. Since the primary transfer body 180 is adhered after the thin film device layer 140 is manufactured, there is no restriction on the process temperature or the like at the time of manufacturing the thin film device layer 140, and it is only necessary to retain the shape at room temperature. In this embodiment mode, a material that is relatively inexpensive and has shape retention properties such as a glass substrate and a synthetic resin is used. The primary transfer body 180 is formed of a material harder than a secondary transfer body (second transfer substrate) 200, which will be described in detail later, and is configured to easily peel the thin film device layer 140 from the original substrate 100.
[0044]
Next, as shown in FIG. 4, light is irradiated from the back side of the substrate 100. This light is applied to the first separation layer 120 after passing through the substrate 100. As a result, in-layer separation and / or interface separation occurs in the first separation layer 120, and the bonding force decreases or disappears.
[0045]
The principle that intralayer separation and / or interfacial separation occurs in the first separation layer 120 is that ablation occurs in the constituent material of the first separation layer 120, the gas contained in the first separation layer 120 is released, Is estimated to be due to phase changes such as melting and transpiration that occur immediately after irradiation.
[0046]
Here, the ablation means that a fixing material that absorbs irradiation light (a constituent material of the first separation layer 120) is photochemically or thermally excited, and a bond between atoms or molecules inside the surface or inside is cut and emitted. In general, all or part of the constituent material of the first separation layer 120 appears as a phenomenon that causes a phase change such as melting or transpiration (vaporization). In addition, the phase change may result in a fine foamed state, resulting in a decrease in bonding strength.
[0047]
Whether the first separation layer 120 causes in-layer separation, interfacial separation, or both depends on the composition of the first separation layer 120 and various other factors, and is one of the factors. The conditions such as the type of light to be irradiated, the wavelength, the intensity, and the reaching depth can be mentioned.
[0048]
The irradiation light may be any light as long as it causes internal separation and / or interfacial separation in the first separation layer 120. For example, X-rays, ultraviolet rays, visible light, infrared rays (heat rays), laser light, Examples include millimeter waves, microwaves, electron beams, radiation (α rays, β rays, γ rays) and the like. Among these, a laser beam is preferable in that it easily causes peeling (ablation) of the first separation layer 120.
[0049]
Examples of laser devices that generate this laser beam include various gas lasers, solid-state lasers (semiconductor lasers), and the like. Excimer lasers, Nd-YAG lasers, Ar lasers, CO lasers, etc. ₂ A laser, a CO laser, a He—Ne laser or the like is preferably used, and an excimer laser is particularly preferable among them.
[0050]
Since the excimer laser outputs high energy in a short wavelength region, it can cause ablation in the first separation layer 2 in an extremely short time, and thus almost causes a temperature rise in the adjacent transfer body 180, the substrate 100, and the like. The first separation layer 120 can be peeled without causing the deterioration or damage.
[0051]
In addition, when ablation is caused in the first separation layer 120, the wavelength of the irradiated laser light is preferably about 100 nm to 350 nm when there is light wavelength dependency.
[0052]
FIG. 10 shows an example of the transmittance of the substrate 100 with respect to the wavelength of light. As shown in the figure, the transmittance increases sharply for a wavelength of 200 nm. In such a case, light with a wavelength of 210 nm or more, for example, Xe-Cl excimer laser light (wavelength 308 nm), KrF laser light (wavelength 248 nm), or the like is irradiated.
[0053]
In addition, when the first separation layer 120 is given separation characteristics by causing a phase change such as outgassing, vaporization, and sublimation, the wavelength of the irradiated laser light is preferably about 350 to 1200 nm.
[0054]
The energy density of the irradiated laser beam, particularly the energy density in the case of an excimer laser, is 10 to 5000 mJ / cm. ² It is preferable to be about 100 to 500 mJ / cm. ² More preferably, it is about. The irradiation time is preferably about 1 to 1000 nsec, more preferably about 10 to 100 nsec. When the energy density is low or the irradiation time is short, sufficient ablation or the like does not occur, and when the energy density is high or the irradiation time is long, the transferred layer 140 is irradiated by the irradiation light transmitted through the first separation layer 120. There is a risk of adverse effects.
[0055]
In addition, as a countermeasure when the irradiation light transmitted through the first separation layer 120 reaches the transferred layer 140 and has an adverse effect, for example, tantalum (Ta) or the like is formed on the first separation layer (laser absorption layer) 120. There is a method of forming a metal film. As a result, the laser light transmitted through the first separation layer 120 is completely reflected at the interface of the metal film 124 and does not adversely affect the thin film device above it. Alternatively, a silicon-based intervening layer such as SiO is formed on the first separation layer 120. ₂ An amorphous silicon layer that is a silicon-based laser absorption layer can also be formed through the step. In this way, the light transmitted through the first separation layer 120 is absorbed by the amorphous silicon layer thereon. However, the transmitted light does not have enough light energy to cause ablation again in the upper amorphous silicon layer. In addition, unlike a metal, a thin film device layer can be formed on an amorphous silicon layer, so that a thin film device layer with excellent quality can be formed by an already established thin film formation technique.
[0056]
Irradiation light represented by laser light is preferably irradiated so that its intensity is uniform. The irradiation direction of the irradiation light is not limited to the direction perpendicular to the first separation layer 120 but may be a direction inclined by a predetermined angle with respect to the first separation layer 120.
[0057]
In addition, when the area of the first separation layer 120 is larger than the one irradiation area of the irradiation light, the entire area of the first separation layer 120 can be irradiated with the irradiation light in a plurality of times. Moreover, you may irradiate the same location twice or more. Further, irradiation light (laser light) of different types and different wavelengths (wavelength regions) may be irradiated twice or more to the same region or different regions.
[0058]
Next, as shown in FIG. 5, a force is applied to the substrate 100 to release the substrate 100 from the first separation layer 120. Although not shown in FIG. 5, the first separation layer 120 may adhere on the substrate 100 after the separation.
[0059]
Next, as shown in FIG. 6, the remaining first separation layer 120 is removed by a method such as cleaning, etching, ashing, polishing, or a combination thereof. As a result, the transferred layer (thin film device layer) 140 is transferred to the primary transfer body 180.
[0060]
If a part of the first separation layer 120 is also attached to the detached substrate 100, it is similarly removed. When the substrate 100 is made of an expensive material such as quartz glass or a rare material, the substrate 100 is preferably used for recycling (recycling). That is, the present invention can be applied to the substrate 100 to be reused, and is highly useful. Here, in the case of once transfer, this step is the final step, and the transfer of the transferred layer 140 to the final transfer body 180 is completed.
[0061]
Next, as shown in FIG. 7, the secondary transfer layer 200 is bonded to the lower surface (exposed surface) of the thin film device layer 140 through the adhesive layer 190.
[0062]
Preferable examples of the adhesive constituting the adhesive layer 190 include various curable types such as a reactive curable adhesive, a thermosetting adhesive, a photocurable adhesive such as an ultraviolet curable adhesive, and an anaerobic curable adhesive. An adhesive is mentioned. The composition of the adhesive may be any, for example, epoxy, acrylate, or silicone. Such an adhesive layer 190 is formed by, for example, a coating method. The material of the adhesive layer 190 can be used for adhesion between the transferred layer 140 and the final transfer layer 180 in the case of once transferring.
[0063]
In the case of using the curable adhesive, for example, after applying the curable adhesive to the lower surface of the transferred layer (thin film device layer) 140 and further joining the secondary transfer body 200, the curable adhesive is used according to the characteristics of the curable adhesive. The curable adhesive is cured by a curing method, and the transferred layer (thin film device layer) 140 and the secondary transfer body 200 are bonded and fixed.
[0064]
When the adhesive is a photo-curing type, light is preferably applied from the outside of the light-transmitting secondary transfer body 200. As the adhesive, if a photo-curing adhesive such as an ultraviolet curing type that does not affect the thin film device layer is used, the light-transmitting primary transfer body 180 or the light-transmitting primary or secondary transfer body 180 is used. , 200 may be irradiated with light from both sides. As the secondary transfer body 200, a flat or curved transparent substrate is used.
[0065]
The secondary transfer body 200 may be inferior to the substrate 100 in characteristics such as heat resistance and corrosion resistance. The reason for this is that in the present invention, the transfer layer (thin film device layer) 140 is formed on the substrate 100 side, and then the transfer layer (thin film device layer) 140 is transferred to the secondary transfer body 200. This is because characteristics required for the body 200, particularly heat resistance, do not depend on temperature conditions or the like when forming the transferred layer (thin film device layer) 140. This also applies to the primary transfer body 180.
[0066]
Therefore, when the maximum temperature during the formation of the transferred layer 140 is Tmax, a material having a glass transition point (Tg) or a softening point of Tmax or less is used as a constituent material of the primary and secondary transfer bodies 180 and 200. Can do. For example, the primary and secondary transfer bodies 180 and 200 can be made of a material having a glass transition point (Tg) or softening point of preferably 800 ° C. or lower, more preferably 500 ° C. or lower, and further preferably 320 ° C. or lower. .
[0067]
Further, the mechanical properties of the primary and secondary transfer bodies 180 and 200 are preferably those having a certain degree of hardness (rigidity and strength), but may be those having flexibility and elasticity. Further, as described above, the secondary transfer body 200 is selected from one that is softer or less rigid than the primary transfer body 180.
[0068]
The combinations of the primary transfer member and the secondary transfer member are as follows. The primary transfer body is glass (or quartz), and the secondary transfer body is plastic. When both are synthetic resins, the thickness of the primary transfer member is larger than that of the secondary transfer member, or the material of the primary transfer member is harder or more rigid than the material of the secondary transfer member. Here, “hard” means that, for example, when transferring a thin film device to a primary transfer body, the thin film device is peeled off from the original substrate. At this time, the primary transfer body is not peeled off from the thin film device. It indicates that the substrate has a strength, rigidity, thickness, material, etc. that can peel the thin film device.
[0069]
In this embodiment, when the thin film device is transferred to the secondary transfer body, it is preferable that both the primary transfer body and the second separation layer 160 are dissolved in a specific solvent. That is, by dissolving the primary transfer body (first transfer substrate) in the solvent, the thin film device can be reliably separated from the primary transfer body in the second separation layer. Conventionally, a water-soluble adhesive is sometimes used as the separation layer, but since the primary transfer body itself is not water-soluble, it is only gradually etched from the end surface of the water-soluble adhesive facing the water. This requires a considerable amount of time to sufficiently peel off the primary transfer body. However, if the transfer body itself is dissolved in a specific solvent in the same manner as the separation layer, the primary transfer body not only on the end face of the separation layer but also on almost the entire surface. Can be separated from the thin film device. At this time, the secondary transfer substrate 200 and the adhesive layer 190 are not dissolved in a specific solvent.
[0070]
From the above viewpoint, suitable combinations of materials of the primary transfer body 180 and the secondary transfer body 200 and specific solvents at the time of secondary transfer are as shown in Table 1 below.
[0071]
Table 1 Primary transfer material, secondary transfer material, secondary transfer solvent

As the constituent material of the primary and secondary transfer bodies 180 and 200, various synthetic resins or various glass materials can be used as long as there is a difference in hardness between them. In particular, various synthetic resins and ordinary (low melting point) inexpensive materials can be used. Glass materials are preferable, and a combination in which the primary transfer body 180 is harder than the secondary transfer body 200 should be selected from these materials.
[0072]
The synthetic resin may be either a thermoplastic resin or a thermosetting resin. For example, polyolefin such as polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer (EVA), cyclic polyolefin, modified Polyolefin, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyamide, polyimide, polyamideimide, polycarbonate, poly- (4-methylbenten-1), ionomer, acrylic resin, polymethyl methacrylate, acrylic-styrene copolymer (AS Resin), butadiene-styrene copolymer, polio copolymer (EVOH), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyester such as precyclohexane terephthalate (PCT), poly Ether, polyetherketone (PEK), polyetheretherketone (PEEK), polyetherimide, polyacetal (POM), polyphenylene oxide, modified polyphenylene oxide, polyarylate, aromatic polyester (liquid crystal polymer), polytetrafluoroethylene, polyfluoride Various types of thermoplastic elastomers such as vinylidene fluoride, other fluororesins, styrene, polyolefin, polyvinyl chloride, polyurethane, fluororubber, chlorinated polyethylene, epoxy resin, phenol resin, urea resin, melamine resin, Saturated polyesters, silicone resins, polyurethanes, etc., or copolymers, blends, polymer alloys, etc. mainly composed of these, may be mentioned, and one or more of these may be combined (for example, two layers) As a laminate of the upper) it can be used.
[0073]
Examples of the glass material include silicate glass (quartz glass), alkali silicate glass, soda lime glass, potash lime glass, lead (alkali) glass, barium glass, borosilicate glass, and the like. Of these, glass other than silicate glass is preferable because it has a lower melting point than silicate glass, is relatively easy to mold and process, and is inexpensive.
[0074]
When a secondary transfer body 200 made of a synthetic resin is used, the large-scale secondary transfer body 200 can be integrally formed and has a complicated shape such as a curved surface or an uneven surface. Even if it exists, it can manufacture easily and can enjoy the various advantages that material cost and manufacturing cost are also cheap. Therefore, the use of a synthetic resin is advantageous in manufacturing a large and inexpensive device (for example, a liquid crystal display).
[0075]
Note that the secondary transfer body 200 is a device that forms an independent device such as a liquid crystal cell, or a device such as a color filter, an electrode layer, a dielectric layer, an insulating layer, or a semiconductor element. It may constitute a part.
[0076]
Further, the primary and secondary transfer bodies 180 and 200 may be materials such as metal, ceramics, stone, and wood paper, or on any surface that constitutes an article (on the surface of a watch or the surface of an air conditioner). Or on the surface of a structure such as a wall, pillar, ceiling, or window glass.
[0077]
Next, as shown in FIG. 8, in the separation layer 160, the primary transfer body is dissolved in a solvent by immersing the post-transfer structure including the primary transfer body, the transfer target layer, and the secondary transfer body in a specific solvent. The transferred layer is peeled from the primary transfer member. When the above-described water-soluble adhesive is used as the second separation layer 160, at least a region including the second separation layer 160 may be immersed in pure water.
[0078]
Finally, by removing the second separation layer 160 attached to the surface of the thin film device layer 140, the thin film device layer 140 transferred to the secondary transfer body 200 can be obtained as shown in FIG. Here, the stacking relationship of the thin film device layer 140 with respect to the secondary transfer body 200 is the same as the stacking relationship of the thin film device layer 140 with respect to the original substrate 100 as shown in FIG.
[0079]
Through the above steps, the transfer of the transferred layer (thin film device layer) 140 to the secondary transfer body 200 is completed. Thereafter, SiO adjacent to the transferred layer (thin film device layer) 140. ₂ Removal of the film, formation of a conductive layer such as wiring on the transfer layer 140, or a desired protective film can also be performed.
[0080]
In the present invention, the layer to be transferred (thin film device layer) 140 itself, which is an object to be peeled, is not directly peeled off, but is separated and transferred to the secondary transfer body 200 by the first separation layer 120 and the second separation layer 160. Therefore, regardless of the characteristics, conditions, etc. of the object to be separated (transferred layer 140), it can be transferred easily, reliably and uniformly, and the object to be separated (transferred layer 140) accompanying the separation operation can be transferred. There is no damage and the high reliability of the transferred layer 140 can be maintained.
[0081]
Next, an example of a specific manufacturing process shown in FIGS. 2 to 9 will be described with reference to FIGS.
(Process 1)
As shown in FIG. 11, on a substrate (for example, a quartz substrate) 100, a first separation layer (for example, an amorphous silicon layer formed by LPCVD) 120 and an intermediate layer (for example, SiO 2). ₂ Film) 142 and an amorphous silicon layer (for example, formed by LPCVD) 143 are sequentially stacked, and then the entire surface of the amorphous silicon layer 143 is irradiated with laser light from above and annealed. Thereby, the amorphous silicon layer 143 is recrystallized to become a polysilicon layer.
(Process 2)
Subsequently, as shown in FIG. 12, the polysilicon layer obtained by laser annealing is patterned to form islands 144a and 144b.
(Process 3)
As shown in FIG. 13, the entire surface including islands 144a and 144b is covered with a gate insulating film 148 by a CVD method.
(Process 4)
As shown in FIG. 14, gate electrodes 150a and 150b made of polysilicon or metal are formed.
(Process 5)
As shown in FIG. 15, a mask layer 170 made of polyimide or the like is formed, and, for example, boron (B) ions are implanted by self-alignment using the gate electrode 150b and the mask layer 170 as a mask. As a result, p + layers 172a and 172b are formed.
(Step 6)
As shown in FIG. 16, a mask layer 174 made of polyimide or the like is formed, and, for example, phosphorus (P) ions are implanted by self-alignment using the gate electrode 150a and the mask layer 174 as a mask. As a result, n + layers 146a and 146b are formed.
(Step 7)
As shown in FIG. 17, an interlayer insulating film 154 is formed, and after selectively forming contact holes, electrodes 152a to 152d are formed.
[0082]
The TFT having the CMOS structure formed in this manner corresponds to the transferred layer (thin film device layer) 140 in FIGS. Note that a protective film may be formed over the interlayer insulating film 154.
(Step 8)
As shown in FIG. 18, a hot-melt adhesive layer 160 as a second separation layer is formed on a TFT having a CMOS structure. At this time, the step formed on the surface layer of the TFT is flattened by the hot-melt adhesive 160. In addition, the 2nd separated layer can also be comprised with an ablation layer like a 1st separated layer, or can also use a water-soluble adhesive agent.
[0083]
Here, it is preferable that a protective layer such as an insulating layer is first formed on a TFT which is a thin film device, and a second separation layer is provided on the protective layer. In particular, when the second separation layer is an ablation layer, the thin film device layer can be protected by the protective layer during ablation.
[0084]
In particular, when the second separation layer is formed of an ablation layer, the second separation layer itself can be formed in multiple layers like the first separation layer. Furthermore, it is better to provide a light shielding layer such as a metal layer between the second separation layer and the thin film device layer. This is because light can be prevented from entering the thin film device layer during ablation.
[0085]
After the formation of the second separation layer, the TFT is attached to the primary transfer body (for example, soda glass substrate) 180 through the hot-melt adhesive layer 160 that is the second separation layer.
(Step 9)
As shown in FIG. 19, for example, Xe—Cl excimer laser light is irradiated from the back surface of the substrate 100. As a result, peeling occurs in the layer of the first separation layer 120 and / or in the interface.
(Process 10)
As shown in FIG. 20, the substrate 100 is peeled off.
(Step 11)
Further, the first separation layer 120 is removed by etching. As a result, as shown in FIG. 21, the TFT having the CMOS structure is transferred to the primary transfer body 180.
(Step 12)
Next, as shown in FIG. 22, for example, an epoxy resin layer 190 is formed on the lower surface of the CMOS TFT as an adhesive layer having a lower curing point than the hot-melt resin layer 160. Next, the TFT is attached to the secondary transfer body 200 made of synthetic resin through the epoxy resin layer 190. Subsequently, heat is applied to cure the epoxy resin layer 190, and the secondary transfer body 200 and the TFT are bonded (bonded).
(Step 13)
Next, as shown in FIG. 23, the heat-meltable resin layer 160 is melted by heat using, for example, an oven 210, and the TFT is peeled off from the primary transfer body 180 with the heat-meltable resin layer 160 as a boundary. Further, the hot-melt resin layer 160 remaining on the lower surface of the TFT is removed by, for example, xylene. As a result, the TFT is transferred to the secondary transfer body 200 as shown in FIG. The state shown in FIG. 24 is the same as that obtained by replacing the substrate 100 and the first separation layer 120 shown in FIG. 17 with the secondary transfer body 200 and the adhesive layer 190. Therefore, the lamination relationship with respect to the substrate 100 used in the TFT manufacturing process is ensured on the secondary transfer body 200. For this reason, the electrodes 152a to 152d are exposed, and contact or wiring to the electrodes 152a to 152d can be easily performed. Note that a protective layer may be formed on the surface layer after the state shown in FIG.
[0086]
FIG. 25 is a view showing a second embodiment of the thin film device transfer method according to the present invention and corresponding to step 8 (FIG. 8) in the first embodiment.
[0087]
In FIG. 25, in a state where the second separation layer 160, the thin film device layer 140, the adhesive layer 190, and the secondary transfer body 200 are formed on the primary transfer body 180, the primary transfer body 180 is melted and removed with a solvent. Examples of combinations of the materials of the primary transfer body 180 and the secondary transfer body 200 and the solvent at the time of secondary transfer to enable the melting and removal are as shown in the above-described table. Note that the second separation layer 160 may be omitted when the primary transfer member 180 is removed by melting.
[0088]
The primary transfer body peeling in the first embodiment is not easy to peel off when the area of the primary transfer body is large, but there is no such problem in the melting removal as in the second embodiment.
[0089]
【Example】
Next, specific examples of the present invention will be described.
Example 1
A quartz substrate (softening point: 1630 ° C., strain point: 1070 ° C., excimer laser transmittance: almost 100%) having a length of 50 mm × width of 50 mm × thickness of 1.1 mm is prepared. An amorphous silicon (a-Si) film is formed as a separation layer (laser light absorption layer) by a low pressure CVD method (Si ₂ H ₆ Gas, 425 ° C.). The film thickness of the first separation layer was 100 nm.
[0090]
Next, on the first separation layer, as an intermediate layer, SiO ₂ A film was formed. This SiO ₂ A liquid phase process was used to form the film. In other words, polysilazane (trade name) manufactured by Tonen Corporation is mixed with xylene, spin-coated on a substrate, and this coating film is heat-treated in an atmosphere containing water vapor to generate SiO. ₂ Converted to a membrane. The thickness of this intermediate layer was 200 nm.
[0091]
Next, an amorphous silicon film having a thickness of 50 nm is formed on the intermediate layer as a transfer layer by a low pressure CVD method (Si ₂ H ₆ The amorphous silicon film was irradiated with laser light (wavelength 308 nm) and crystallized to obtain a polysilicon film. Thereafter, the polysilicon film was subjected to predetermined patterning to form regions serving as the source / drain / channel of the thin film transistor. After this, the intermediate layer SiO ₂ The gate insulating film SiO made of polysilazane using the same liquid phase process ₂ Formed. Thereafter, a gate electrode was formed on the gate insulating film by a liquid phase process. For this purpose, a coating solution made in the form of Asahi Denka Kogyo Co., Ltd .: Adeka ITO coating film / ITO-103L is spin-coated, and this is applied by the above-described first and second heat treatment units 603A and 603B. A coated ITO film was formed by heat treatment.
Thereafter, a metal plating layer was formed on the coated ITO film. Then, the coated ITO film and the metal plating layer were patterned to form a gate electrode. By ion-implanting using this gate electrode as a mask, source / drain regions were formed in a self-aligned manner (self-line), and a thin film transistor was formed. Thereafter, electrodes and wirings connected to the source / drain regions and wirings connected to the gate electrode are formed as necessary. These electrodes and wirings were also formed of the same material using a liquid phase process in the same manner as the gate electrode.
[0092]
Next, an acetone-soluble adhesive was applied on the thin film transistor, and a large transparent vinyl chloride resin substrate having a length of 200 mm, a width of 300 mm, and a thickness of 1.1 mm was joined as a primary transfer body.
[0093]
Next, Xe—Cl excimer laser (wavelength: 308 nm) was irradiated from the quartz substrate side to cause peeling (in-layer peeling and interface peeling) in the first separation layer. The energy density of the irradiated Xe-Cl excimer laser is 250 mJ / cm. ² The irradiation time was 20 nsec. The excimer laser irradiation includes spot beam irradiation and line beam irradiation. In the case of spot beam irradiation, spot irradiation is performed on a predetermined unit region (for example, 8 mm × 8 mm), and this spot irradiation is 1 / of the unit region. Irradiate while shifting by about 10 steps. In the case of line beam irradiation, irradiation is performed while shifting a predetermined unit area (for example, 378 mm × 0.1 mm or 378 mm × 0.3 mm (these are areas where 90% or more of energy is obtained)) by about 1/10. I will do it. Thereby, each point of the first separation layer is irradiated at least 10 times. This laser irradiation is performed while shifting the irradiation region with respect to the entire surface of the quartz substrate.
[0094]
Thereafter, the quartz substrate and the primary transfer body were peeled off at the first separation layer, and the thin film transistor and the intermediate layer formed on the quartz substrate were primarily transferred to the primary transfer body.
[0095]
Thereafter, the first separation layer adhering to the surface of the intermediate layer was removed by etching, washing, or a combination thereof. Further, the same treatment was performed on the quartz substrate and it was reused.
[0096]
Further, an ultraviolet curable adhesive was applied to the lower surface of the exposed intermediate layer (film thickness: 100 μm), and a large-sized film having a length of 200 mm × width 300 mm × thickness 1.1 mm as a secondary transfer member was applied to the coating film. After bonding the transparent fluororesin substrate, the adhesive was cured by irradiating with ultraviolet rays, and these were bonded and fixed.
[0097]
Thereafter, the primary transfer member was removed by immersion in acetone. Thereby, the thin film transistor and the intermediate layer were secondarily transferred to the fluororesin substrate side as a secondary transfer body. The thickness of the primary transfer member was different from that of the secondary transfer member so that the hardness of the primary transfer member was higher than that of the secondary transfer member.
[0098]
Here, if the primary transfer body is larger than the quartz substrate, the primary transfer from the quartz substrate as in this embodiment is repeatedly performed on different areas in a plan view, and the primary transfer body is placed on the quartz substrate. More thin film transistors than the number of thin film transistors that can be formed can be formed. Furthermore, it can be repeatedly laminated on the primary transfer body to form more thin film transistors. Alternatively, the substrate serving as the secondary transfer body may be larger than the primary transfer body and the quartz substrate, and the secondary transfer may be repeatedly performed to form more thin film transistors than the number of thin film transistors that can be formed on the quartz substrate. it can.
[0099]
【The invention's effect】
As described above, according to the present invention, in the thin film device transfer / manufacturing method using the double transfer technology, the transfer layer is peeled or separated from the first transfer substrate in preference to the second transfer substrate. It is possible to provide a transfer / separation technique for a thin film device that can be used.
[0100]
Furthermore, according to the present invention, it is possible to provide a transfer / separation technique for a thin film device in which a transfer body can be sufficiently peeled off from a transfer layer by a release layer in the twice transfer technique.
[Brief description of the drawings]
FIG. 1 shows a thin film device of the present invention. Manufacturing It is sectional drawing which shows the 1st process in 1st Embodiment of a method.
FIG. 2 shows the thin film device of the present invention. Manufacturing It is sectional drawing which shows the 2nd process in 1st Embodiment of a method.
FIG. 3 shows the thin film device of the present invention. Manufacturing It is sectional drawing which shows the 3rd process in 1st Embodiment of a method.
FIG. 4 shows the thin film device of the present invention. Manufacturing It is sectional drawing which shows the 4th process in 1st Embodiment of a method.
FIG. 5 shows a thin film device of the present invention. Manufacturing It is sectional drawing which shows the 5th process in 1st Embodiment of a method.
FIG. 6 shows the thin film device of the present invention. Manufacturing It is sectional drawing which shows the 6th process in 1st Embodiment of a method.
FIG. 7 shows the thin film device of the present invention. Manufacturing It is sectional drawing which shows the 7th process in 1st Embodiment of a method.
FIG. 8 shows a thin film device of the present invention. Manufacturing It is sectional drawing which shows the 8th process in 1st Embodiment of a method.
FIG. 9 shows a thin film device of the present invention. Manufacturing It is sectional drawing which shows the 9th process in 1st Embodiment of a method.
10 is a diagram showing a change in transmittance of the first substrate (substrate 100 in FIG. 1) with respect to the wavelength of laser light.
11 is a cross-sectional view showing a first step for forming the thin film device of FIG. 2; FIG.
12 is a cross-sectional view showing a second step in the second embodiment for forming the thin film device of FIG. 2; FIG.
13 is a cross-sectional view showing a third step for forming the thin film device of FIG. 2; FIG.
14 is a cross-sectional view showing a fourth step for forming the thin film device of FIG. 2; FIG.
15 is a cross-sectional view showing a fifth step for forming the thin film device of FIG. 2. FIG.
16 is a cross-sectional view showing a sixth step for forming the thin film device of FIG. 2. FIG.
17 is a cross-sectional view showing a seventh step for forming the thin film device of FIG. 2. FIG.
FIG. 18 is a cross-sectional view of an eighth step, illustrating the step of FIG. 3 with a specific structure.
FIG. 19 is a cross-sectional view of a ninth step, illustrating the step in FIG. 4 with a specific structure.
FIG. 20 is a cross-sectional view of a tenth step illustrating the step of FIG. 5 with a specific structure.
FIG. 21 is a cross-sectional view of an eleventh step for describing the step of FIG. 6 with a specific structure.
22 is a cross-sectional view of a twelfth process illustrating the process of FIG. 7 with a specific structure. FIG.
FIG. 23 is a cross-sectional view of a thirteenth step for describing the step of FIG. 8 with a specific structure.
FIG. 24 is a cross-sectional view of the fourteenth step for describing the step in FIG. 9 with a specific structure.
FIG. 25 shows a thin film device according to a second embodiment of the invention. Manufacturing It is sectional drawing which shows the state of the secondary transfer (corresponding to the process 8 (FIG. 8) of 1st embodiment) in a method.

Claims (4)

A first step of forming a first separation layer on the original substrate; a second step of forming a transfer layer comprising a plurality of thin films including a source electrode and a drain electrode on the first separation layer; A third step of bonding a first transfer substrate on the transfer layer; a fourth step of peeling the transfer layer from the original substrate with the first separation layer as a boundary; and A fifth step of bonding a second transfer substrate to the lower side, and removing the first transfer substrate from the first transfer substrate while dissolving and removing the first transfer substrate in a specific solvent, thereby removing the transferred layer from the second transfer substrate. And a sixth step of transferring to the transfer substrate.
The method of manufacturing a thin film device, wherein the material of the first transfer substrate is acrylic resin, the material of the second transfer substrate is polyethylene, and the solvent is IPA. A first step of forming a first separation layer on the original substrate; a second step of forming a transfer layer comprising a plurality of thin films including a source electrode and a drain electrode on the first separation layer; A third step of bonding a first transfer substrate on the transfer layer; a fourth step of peeling the transfer layer from the original substrate with the first separation layer as a boundary; and A fifth step of bonding a second transfer substrate to the lower side, and removing the first transfer substrate from the first transfer substrate while dissolving and removing the first transfer substrate in a specific solvent, thereby removing the transferred layer from the second transfer substrate. And a sixth step of transferring to the transfer substrate.
The method of manufacturing a thin film device, wherein the material of the first transfer substrate is vinyl chloride resin or polyethersulfone, the material of the second transfer substrate is fluororesin, and the solvent is acetone.   3. The method of manufacturing a thin film device according to claim 1, wherein the first transfer substrate is selected from those harder than the second transfer substrate. 4.   At least one thin film of the plurality of thin films and the first and second separation layers constituting the thin film device is formed using a liquid phase process that is solidified after a liquid containing a component of the thin film is applied. The manufacturing method of the thin film device in any one of Claims 1-3.

Images