JP4139129B2 - Method for manufacturing polarization separating element, bonding apparatus, and optical pickup apparatus - Google Patents

Method for manufacturing polarization separating element, bonding apparatus, and optical pickup apparatus Download PDF

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JP4139129B2
JP4139129B2 JP2002127926A JP2002127926A JP4139129B2 JP 4139129 B2 JP4139129 B2 JP 4139129B2 JP 2002127926 A JP2002127926 A JP 2002127926A JP 2002127926 A JP2002127926 A JP 2002127926A JP 4139129 B2 JP4139129 B2 JP 4139129B2
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rotation
transparent substrate
birefringent film
organic birefringent
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JP2003322720A (en
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明繁 村上
康弘 東
秀一 曳地
孝二 森
哲司 守
剛 鈴土
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Ricoh Co Ltd
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Ricoh Co Ltd
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【０００１】
本発明は、偏光分離素子とその作製方法、接着装置及び光ピックアップ装置に関する。
【０００２】
【従来の技術】
光ディスク用の光ピックアップ装置では、光源からの入射光束と光ディスクにより反射され光ディスクの情報を帯びた戻り光束とを分離して、戻り光束を効率良く光検出手段に導くために偏光分離素子が用いられている。偏光分離素子としてプリズムを接着したビームスプリッタが、λ／４波長板と共に用いられているが、光ピックアップ装置の小型化・低コスト化の要請に答えるため、薄型化の可能な複屈折回折格子型の偏光分離素子の使用が意図されている。
【０００３】
特開２０００−７５１３号公報は、この種の偏光分離素子として、透明基板上に入射光の異なる振動面に対し屈折率が異なる有機複屈折膜を接着し、この有機複屈折膜の表面に周期的な凹凸による回折格子を形成したものを開示している。有機複屈折膜としては、延伸した有機高分子膜が用いられている。
この偏光分離素子では、接着剤を用いて有機複屈折膜を透明基板に接着しているが、回折格子を透過する光束に対して光路長を一定にするためには、接着剤層の厚さを均一にして有機複屈折膜の表面を平坦化する必要がある。また、接着剤層に気泡が入ると、入射・射出光束が気泡により散乱されて回折効率が低下するため、気泡を巻き込まない接着法が必要となる。
【０００４】
透明基板へ有機複屈折膜を接着する方法の一例として、貼り合わせ光ディスクで用いられているスピンナー法がある。スピンナー法による貼り合わせ光ディスクの作製工程を、図１３を用いて説明する。図１３（ａ）に示すように、第１の基板２０１に形成されたハブ２０２をスピンテーブル１０のセンターピン２０３にさし込み、スピンテーブル１０を回転させながら第１の基板２０１にディスペンサー１２で紫外線硬化型接着剤３を滴下する。図１３（ｂ）に示すように、第１の基板２０１の全面に紫外線硬化型接着剤３が広がったらスピンテーブル１０の回転を停止し、図１３（ｃ）に示すように、第２の基板２０４に形成されたハブ２０５をスピンテーブル１０のセンターピン２０３にさし込み、第１の基板２０１と第２の基板２０４を接触させる。次に、図１３（ｄ）に示すように、第１の基板２０１と第２の基板２０４とが載置されたスピンテーブル１０を回転させ、余分な紫外線硬化型接着剤３を振り切り接着層厚さを一定し、図１３（ｅ）に示すように、スピンテーブル１０の回転を停止し、紫外線（ＵＶ）を照射して紫外線硬化型接着層３を硬化し、貼り合わせ光ディスクを完成させる。
【０００５】
スピンナー法を有機複屈折膜の接着に適応して、大きさが数ｍｍ程度の偏光分離素子を作製しようとする場合、直径４〜８インチの透明基板に接着された有機複屈折膜上に数１０〜数１００個の回折格子をアレイ状に形成し、その後ダイシングによって個々の偏光分離素子を取り出すことが考えられる。１枚の基板から取れる偏光分離素子数を多くしようとすると、有機複屈折膜や透明基板にはハブを、スピンテーブル１０には、センターピンを設けない方が好ましい。例えば、図１４（ａ）に示すように、センターピンのないスピンテーブル１０に透明基板１を真空吸着し、その後、透明基板１の中央に紫外線硬化型接着剤３を滴下し、スピンテーブル１０を回転して紫外線硬化型接着剤３を透明基板１の滴下面全面に広げた後、有機複屈折膜５を透明基板１上に載せることが考えられる。
【０００６】
【発明が解決しようとする課題】
図１４に示す偏光分離素子の作製方法では、有機複屈折膜５にハブが、スピンテーブル１０にセンターピンが夫々ないので、有機複屈折膜５は、スピンテーブル１０上で固定されずフリーな状態で透明基板に乗ることになる。有機複屈折膜５を紫外線硬化型接着剤３が塗布された透明基板１に載せる場合、一般的に載置装置を用いるが、スピンテーブル１０の回転中心に有機複屈折膜５の中心を正確に合わせることは、載置装置の機械的精度の点から困難な場合が多い。有機複屈折膜５がスピンテーブル１０の回転中心に乗っていない場合、スピンテーブル１０を回転させると、図１４（ｂ）に示すように、有機複屈折膜５が透明基板１に対して位置ずれを起こしてしまう。この位置ずれが大きい場合、透明基板１から有機複屈折膜５がはみ出してしまう。
【０００７】
紫外線照射によって紫外線硬化型接着剤３を硬化させた後、回折格子を形成するためリソグラフィー／ドライエッチングを行うが、装置内や工程間の搬送時には透明基板１の側面を側方からクランプして行うことが多く、透明基板１から有機複屈折膜３がはみ出しているとクランプできず搬送が困難となり、回折格子を形成できない。
【０００８】
スピンテーブル１０の回転中に有機複屈折膜５の位置ずれを防止するためには、回転中に紫外線を照射する方法が考えられる。例えば、特開平１０-３３４５２１号公報や特開２０００−２６８４１６号公報に記載の、貼り合わせ光ディスクの作製方法では、回転中に紫外線を照射して紫外線硬化型接着剤を硬化する方法が提案されている。しかしながら偏光分離素子の作製においては、接着層厚さを均一化するため基板をある程度回転させた後に紫外線を照射しなければならないので、有機複屈折膜の位置ずれを完全に防止することは困難であった。
【０００９】
有機複屈折膜５を透明基板上に載置する載置装置にＣＣＤなどを用いた画像認識機能を搭載し、スピンテーブ１０の回転中心と有機複屈折膜５の中心を検出し、載置装置にフィードバック制御をかけながらスピンテーブルの回転中心に有機複屈折膜の中心を置く場合には、スピンテーブルの回転中心と有機複屈折膜の中心との位置合わせ精度を著しく向上できるため、スピンテーブルの回転中に有機複屈折膜の位置ずれが起きにくい。しかし、載置装置に画像認識機能やフィードバック機構を設ける必要があり、載置装置のコスト上昇を招いてしまう。また貼り合わせ時に位置検出やフィードバック制御を行うため、貼り合わせ工程のスループットが低下してしまい、安価に偏光分離素子を作製することが困難になる。
【００１０】
本発明は、透明基板に有機複屈折膜を接着する際に有機複屈折膜の透明基板からのはみ出しや位置ズレを抑制する偏光分離素子の作製方法や接着装置を提供することを目的としている。
本発明は、基板間での接着層厚さのバラツキを小さくする偏光分離素子の作製方法、歩留の向上や個々の素子間で回折効率を揃えることができる偏光分離素子を提供することを目的とする。
本発明は、従来構造よりも小型化が実現できる光ピックアップ装置を提供することを目的とする。
【００１１】
【課題を解決するための手段】
本発明の偏光分離素子の作製方法は、透明基板上に、入射光の異なる振動面に対して屈折率が異なる有機複屈折膜を接着する接着工程と、有機複屈折膜上に周期的なマスクパターンを形成し、このマスクパターンを用いて有機複屈折膜をエッチングして周期的な凹凸による回折格子を形成する工程とを有し、次のことを特徴としている。
【００１２】
請求項１では、接着工程が、透明基板上に紫外線硬化型接着剤を塗布する工程、紫外線硬化型接着剤上に有機複屈折膜を載せるセット工程、有機複屈折膜が載せられた透明基板を第１の回転で回転する第１回転工程、第１の回転で回転する透明基板の回転を止めて有機複屈折膜を透明基板上で滑動して位置修正を行う修正工程、透明基板を第２の回転で回転する第２回転工程、第２の回転で回転する透明基板の回転を止め、紫外線を照射して紫外線硬化型接着剤を硬化する硬化工程を有し、第１の回転によって有機複屈折膜が透明基板上で略動かなくなるまで第１回転工程と修正工程とを繰り返し、その後、第２回転工程と硬化工程とを行うことを特徴としている。
【００１３】
請求項４では、接着工程が、透明基板上に紫外線硬化型接着剤を塗布する工程、紫外線硬化型接着剤上に有機複屈折膜を載せるセット工程、有機複屈折膜が載せられた透明基板を第１の回転で回転する第１回転工程、第１の回転で回転する透明基板の回転を止めて有機複屈折膜を透明基板上で滑動して位置修正を行う修正工程、透明基板を第２の回転で回転する第２回転工程、第２回転工程中に紫外線を照射して、紫外線硬化型接着剤を半硬化する半硬化工程、第２の回転で回転する透明基板の回転を止め、紫外線を照射して紫外線硬化型接着剤を硬化する硬化工程を有し、第１の回転によって有機複屈折膜が透明基板上で略動かなくなるまで第１回転工程と修正工程とを繰り返し、その後、第２回転工程、半硬化工程、硬化工程を行うことを特徴としている。
【００１４】
請求項２，５では、第１回転工程と修正工程を繰り返し、かつ第１回転工程での透明基板の回転が複数の回転数を有する場合、Ｘ回目の第１の回転の回転数をＲ１（Ｘ）［ｒｐｍ］、第２回転工程での第２の回転の最大の回転数をＲ２ｍａｘ［ｒｐｍ］すると、Ｒ２ｍａｘ＝Ｒ１（Ｘ）≧Ｒ１（Ｘ−１）≧・・・≧Ｒ１（１） 但しＸ≧２の関係にあることを特徴としている。
【００１５】
請求項３、６では、第１回転工程と修正工程を繰り返し、かつＲ１（Ｘ）が複数の回転数を有する場合、Ｒ１（Ｘ）が等しい時の回転時間の総和が透明基板間一定であることを特徴としている。
【００１７】
本発明の有機複屈折膜の接着装置は、透明基板を保持するスピンテーブル、このスピンテーブルを回転させる回転機構、スピンテーブルに保持された透明基板に、紫外線硬化型接着剤を塗布する塗布機構、透明基板上に塗布された紫外線硬化型接着剤の上に有機複屈折膜を載置する載置機構、有機複屈折膜を介して紫外線硬化型接着剤に紫外線を照射する紫外線照射機構と、透明基板上に載置された有機複屈折膜を当該透明基板上で滑動して位置を修正する位置調整機構とを有することを特徴としている。
【００１８】
【発明の実施の形態】
以下に偏光分離素子の作製方法の実施の形態を、幾つかの具体的な実施例に即して説明する。偏光分離素子の作製方法は、透明基板上に、入射光の異なる振動面に対して屈折率が異なる有機複屈折膜を接着する接着工程と、この有機複屈折膜上に周期的なマスクパターンを形成し、このマスクパターンを用いて有機複屈折膜をエッチングして周期的な凹凸による回折格子を形成する工程とを有している。
【００１９】
【実施例】
実施例１
図１を参照して実施例１の作成方法を説明する。図１（ａ）〜図１（ｋ）は、偏光分離素子の作製方法の工程を示すものである。図１（ａ）では、直径１６５ｍｍ、厚さ１．５ｍｍのショット製光学ガラスＢＫ７からなる透明基板１をスピンテーブル１０に載せ、真空吸着によってスピンテーブル１０に固定し、スピンテーブル１０を１０〜５０ｒｐｍで回転させながら、透明基板１の中央部にディスペンサー１２を用いて屈折率１．５２、粘度：５００ｃｐのアクリル系の紫外線硬化型接着剤３を８〜１１ｇ滴下する。滴下後、スピンテーブル１０を３００ｒｐｍで回転し、図１（ｂ）に示すように、透明基板１の滴下面全面に紫外線硬化型接着剤３を広げ、その後スピンテーブル１０の回転を停止する。図１（ａ）、図１（ｂ）は、透明基板１上に紫外線硬化型接着剤３を塗布する工程を示す。
【００２０】
図１（ｃ）において、スピンテーブル１０の回転停止後、広げられた紫外線硬化型接着剤３の上に、後述する載置装置を用いて透明基板１の直径よりも小径な、直径１５５ｍｍ、厚さ８０μｍの有機複屈折膜５を、その中心をスピンテーブル１０の回転中心に略合わせながら載置する。図１（ｃ）は、紫外線硬化型接着剤３上に有機複屈折膜５を載せるセット工程を示す。
【００２１】
載置後、図１（ｄ）に示すように、スピンテーブル１０を４００ｒｐｍで第１の回転を行い、紫外線硬化型接着剤３を振り切る。ここで、Ｘ回目の第１の回転の回転数をＲ１（Ｘ）［ｒｐｍ］、Ｘ回目の第１の回転の回転時間をＴ１（Ｘ）とすると、Ｒ１（１）＝４００ｒｐｍ、Ｔ１（１）＝３秒となる。図１（ｄ）は、第１回転工程を示す。
【００２２】
図１（ｅ）において、スピンテーブル１０の回転を停止して有機複屈折膜５の位置ずれを観察したところ、図２（ａ）に示すように、有機複屈折膜５が透明基板１上で外側に５ｍｍ程度動いており、有機複屈折膜５の中心とスピンテーブル１０の回転中心が合わなくなっていた。そのため、調整治具２０を用いて有機複屈折膜５の外側にずれた側の端部を透明基板１の中心側へ押し、透明基板１上を滑るように有機複屈折膜５を動かし（以後、滑るように動かすことを「滑動」と略す）、図２（ｂ）に示すように、有機複屈折膜５の位置修正を行った。つまり透明基板１と有機複屈折膜５の中心を合わせ、有機複屈折膜５が透明基板１からはみ出さない位置へ有機複屈折膜５を動かした。図１（ｅ）は修正工程を示す。
【００２３】
このような修正工程後、図１（ｆ）に示すように、スピンテーブル１０を再度４００ｒｐｍで第１の回転（Ｒ１（２）＝４００ｒｐｍ、回転時間Ｔ１（２）＝７秒）を行い、紫外線硬化型接着剤３を振り切り、その後スピンテーブル１０の回転を停止して有機複屈折膜５の位置ずれを観察したところ、有機複屈折膜５は透明基板１上でほとんど動いていなかった。
【００２４】
観察後、スピンテーブル１０を７００ｒｐｍで第１の回転（Ｒ１（３）＝７００ｒｐｍ、回転時間Ｔ１（３）＝２秒）を行い、紫外線硬化型接着剤３を振り切る。この後、スピンテーブル１０の回転を停止して有機複屈折膜５の位置ずれを観察したところ、有機複屈折膜５は透明基板１上で約８ｍｍ程度動いていた。このため、図１（ｅ）、図２（ａ）に示すように調整治具２０を用い、有機複屈折膜５を透明基板１上で滑動し、有機複屈折膜５の位置修正を行った。
【００２５】
修正後、図１（ｆ）でスピンテーブル１０を再度７００ｒｐｍで第１の回転（Ｒ１（４）＝７００ｒｐｍ、回転時間Ｔ１（４）＝６秒）を行い、紫外線硬化型接着剤３を振り切り、その後にスピンテーブル１０の回転を停止して有機複屈折膜５の位置ずれを観察したところ、有機複屈折膜５は透明基板１上で約２ｍｍ程度動いていた。観測後、図１（ｅ）、図２（ａ）に示す調整治具２０を用い、有機複屈折膜５を透明基板１上で滑動し、有機複屈折膜５の位置修正を行った。
【００２６】
修正後、図１（ｆ）でスピンテーブル１０を再度７００ｒｐｍで第１の回転（Ｒ１（５）＝７００ｒｐｍ、回転時間Ｔ１（５）＝１０秒）を行い、紫外線硬化型接着剤３を振り切る。そして、スピンテーブル１０の回転を停止して有機複屈折膜５の位置ずれを観察したところ、有機複屈折膜５は透明基板１上でほとんど動いていなかった。
【００２７】
観察後、スピンテーブル１０を再度７００ｒｐｍで第１の回転（Ｒ１（６）＝７００ｒｐｍ、回転時間Ｔ１（６）＝１２秒）を行い、紫外線硬化型接着剤３を振り切る。その後スピンテーブル１０の回転を停止して有機複屈折膜５の位置ずれを観察したところ、有機複屈折膜５は透明基板１上でほとんど動いていなかった。
【００２８】
観察後スピンテーブル１０を９００ｒｐｍで第１の回転（Ｒ１（７）＝９００ｒｐｍ、回転時間Ｔ１（７）＝４秒）を行い、紫外線硬化型接着剤３を振り切る。その後スピンテーブル１０の回転を停止して有機複屈折膜５の位置ずれを観察したところ、有機複屈折膜５は透明基板１上で約８ｍｍ程度動いていた。
【００２９】
観測後、図１（ｅ）、図２（ａ）に示す調整治具２０を用い、有機複屈折膜５を透明基板１上で滑動し、有機複屈折膜５の位置修正を行った。修正後、図１（ｆ）でスピンテーブルを再度９００ｒｐｍで第１の回転（Ｒ１（８）＝９００ｒｐｍ、回転時間Ｔ１（８）＝１０秒）を行い、紫外線硬化型接着剤３を振り切る。その後スピンテーブル１０の回転を停止して有機複屈折膜５の位置ずれを観察したところ、有機複屈折膜５は透明基板１上で約２ｍｍ程度動いていた。観察後、調整治具２０を用い、有機複屈折膜５を透明基板１上で滑動し、有機複屈折膜５の位置修正を行った。
【００３０】
修正後、スピンテーブル１０を再度９００ｒｐｍで第１の回転（Ｒ１（９）＝９００ｒｐｍ、回転時間Ｔ１（９）＝２２秒）を行い、紫外線硬化型接着剤３を振り切る。その後スピンテーブル１０の回転を停止して有機複屈折膜５の位置ずれを観察したところ、有機複屈折膜５は透明基板１上でほとんど動いていなかった。
【００３１】
観察後、スピンテーブル１０を再度９００ｒｐｍで第１の回転（Ｒ１（１０）＝９００ｒｐｍ、回転時間Ｔ１（１０）＝５４秒）を行い、紫外線硬化型接着剤３を振り切る。その後、スピンテーブル１０の回転を停止して有機複屈折膜５の位置ずれを観察したところ、有機複屈折膜５は透明基板１上でほとんど動いていなかった。図３に、第１回転工程での第１の回転の回転数及び回転時間の推移を示す。
【００３２】
図１（ｇ）は、第２回転工程を示すもので、スピンテーブル１０を回転（第２の回転、３ステップで回転数を４００ｒｐｍから９００ｒｐｍに上げ、９００ｒｐｍで３０秒間保持）し、紫外線硬化型接着剤３を振り切り、紫外線硬化型接着剤３の接着層厚さを面内で一定にした。ここで第２の回転での最大の回転数をＲ２ｍａｘ［ｒｐｍ］すると、Ｒ２ｍａｘ＝９００ｒｐｍとなる。また第２回転工程中に、硬化前の紫外線硬化型接着剤３を溶解し、かつ有機複屈折膜５を溶解しない有機溶媒３１（本例ではイソプロピルアルコールを使用）を有機複屈折５と透明基板１の境界近傍にリンス機構３０より滴下し、透明基板１周辺の接着剤残を除去した。
【００３３】
次に図１（ｈ）に示すように、スピンテーブル１０の回転を停止し、有機複屈折膜５側から、図示しない高圧水銀灯を用いて紫外線ＵＶ（第１の紫外線）を照射し、紫外線硬化型接着剤３を硬化する。図１（ｈ）は硬化工程を示す。以後、有機複屈折膜５が接着された透明基板１を基板６０と略す。
【００３４】
図１（i）に示すように、作製された基板６０をスピンテーブル１０から外し、有機複屈折膜５上にポジレジストを１．１μｍの厚さに塗布し、６０℃、３０分のプリベークを行う。その後、基板６０を周知の図示しない縮小投影露光装置（ＮＡ＝０．４５、σ＝０．６、波長：I）に装着し、１０００周期ある１．５μｍラインアンドスペースパターンのレチクルを用いて露光を行い、現像液ＮＭＤ−３を用いて現像を行い、１００℃、３０分のポストベークを行い、周期的なレジストパターンを完成させた。その後、前記のレジストパターン上にスパッタ法によってアルミニウム（Ａｌ）を蒸着し、引き続きアセトンを用いてレジストを溶解してアルミニウム（Ａｌ）のリフトオフを行い、レジストパターンを反転させたアルミニウム（Ａｌ）パターンを完成させた。その後、ＥＣＲエッチング装置を用い酸素ガスを主成分とするエッチングガス雰囲気中で、前記のアルミニウム（Ａｌ）パターンを金属マスクにして有機複屈折膜５を深さ４μｍエッチングした。
その後リン酸系のアルミニウム（Ａｌ）エッチング液を用いてアルミニウム（Ａｌ）パターンを除去し、１０００周期ある凹凸状の格子となる回折格子６１を完成させた。
【００３５】
図１（ｊ）に示すように、平面加工したφ２５０ｍｍ、厚み５０ｍｍのステンレス台上に回折格子を形成した基板６０を置き、回折格子６１面に光学的に等方的なアクリル系紫外線硬化型接着剤としての等方性接着剤１１をマイクロシリンジで１．２ｍｌ滴下する。そして両面を光学研磨した直径１６５ｍｍ、厚み１ｍｍ、材質：ショット製光学ガラスＢＫ７の対向透明基板９を載せ、さらに対向透明基板９上に光学研磨した光学ガラスを載せ、対向透明基板９に１００ｇｆ／ｃｍ２の圧力を加え、等方性接着剤１１を被接着面全面に広げる。なお、対向透明基板９の被接着面と対向する面となる自由表面（空気と接する面）には、入射光の反射が最小となるよう反射防止膜（図示せず）を形成しておく。この状態で対向透明基板を通して紫外光を照射し、等方性接着剤１１を硬化する。図１（ｊ）において、符号１Ａは、このようにして対向透明基板１１を一体化した中間完成体と呼ぶ。
【００３６】
次いで、図１（ｋ）に示すように、中間完成体１Ａに含まれている数１００個の回折格子６１を、ダイシングソー１５を用いて５ｍｍ角（各々が、１個の回折格子を有する）」に切りだし、複数個の偏光分離素子１００を完成させる。図１（ｉ）、図１（ｊ）は、回折格子を形成する工程を示す。
【００３７】
図１（ａ）〜（ｈ）の工程により有機複屈折膜５を接着した基板６０を、ダイシングソー１５を用いて切断し、２００倍の金属顕微鏡で断面を観察し、基板６０の直径方向での接着層厚さを測定（測定範囲：有機複屈折膜端から５〜１３０ｍｍ）した。この測定結果を図４に示す。本条件での接着層厚さは平均２８μｍで、直径方向で略均一であることが確認された。
【００３８】
実施例１の作製方法によれば、第１の回転によって有機複屈折膜５が透明基板１上で略動かなくなるまで第１回転工程と修正工程とを繰り返し、その後、第２回転工程と硬化工程とを行うので、透明基板１からの有機複屈折膜５のはみ出しを防止することができる。
【００３９】
また、第１回転工程と修正工程とを繰り返し、かつ第１回転工程での透明基板１の回転が複数の回転数を有する場合、Ｘ回目の第１の回転の回転数をＲ１（Ｘ）［ｒｐｍ］、第２回転工程での第２の回転の最大の回転数をＲ２ｍａｘ［ｒｐｍ］すると、Ｒ２ｍａｘ＝Ｒ１（Ｘ）≧Ｒ１（Ｘ−１）≧・・・≧Ｒ１（１） 但しＸ≧２の関係になっている。よって第１回転工程と修正工程とを繰り返す毎に回転数が増加し、最終的には第１の回転の回転数は第２の回転の最大値、つまりＲ２ｍａｘに一致する。
【００４０】
ここで第１の回転の回転数が第２の回転の最大値（Ｒ２ｍａｘ）に一致した時も、有機複屈折膜５が透明基板１上で略動かなくなるまで第１回転工程と修正工程とを繰り返すので、第１の回転を行った後、第２の回転を実施しても有機複屈折膜５は透明基板１上でほとんど動かず、透明基板１の中心と有機複屈折膜５の中心が略一致した状態に保たれる。このため、有機複屈折膜５の端部と透明基板１の端部の距離を小さく、すなわち、有機複屈折膜５の直径と透明基板１の直径の差を小さくすることができる。この結果、透明基板１上で偏光分離素子１００を形成できる面積を大きくでき、１枚の透明基板１から取れる偏光分離素子１００を多くできる。さらに上記の工程を取ることで、図４に示したように、有機複屈折膜５を接着する接着層厚さを面内で略均一にすることができる。
【００４１】
本実施例では、有機複屈折膜５をそのまま透明基板１に接着したが、有機複屈折膜５の一面に粘着剤を介して有機高分子からなる保護膜が付いた有機複屈折膜を用い、かつ保護膜の付いていない面で透明基板１に接着し、硬化用の紫外線照射後に保護膜を剥離すると、透明基板１と有機複屈折膜５の貼り合わせ工程中は有機複屈折膜表面が保護膜で被覆されているため、有機複屈折膜５表面に異物やキズが付く確率を非常に小さくできる。このため、リソグラフィー工程において異物やキズによって発生するパターン欠陥を低減できるので、偏光分離素子１００の製造歩留を向上することができる。
【００４２】
実施例２
図１（ａ）において、直径１６５ｍｍ、厚さ１．５ｍｍのショット製光学ガラスＢＫ７からなる透明基板１をスピンテーブル１０に載せ、真空吸着によってスピンテーブル１０に固定し、スピンテーブル１０を１０〜５０ｒｐｍで回転させながら、透明基板１の中央部にディスペンサー１２を用いて屈折率１．５２、粘度：５００ｃｐのアクリル系の紫外線硬化型接着剤３を８〜１１ｇ滴下する。滴下後、スピンテーブルを３００ｒｐｍで回転させ、図１（ｂ）に示すように、透明基板１の滴下面全面に紫外線硬化型接着剤３を広げ、その後スピンテーブルの回転を停止する。
【００４３】
図１（ｃ）では、スピンテーブル１０の回転停止後、広げられた紫外線硬化型接着剤３の上に、後述する載置装置を用いて透明基板１の直径よりも小径な、直径１５５ｍｍ、厚さ８０μｍの有機複屈折膜５を、その中心をスピンテーブル１０の回転中心に略合わせながら載置する。
【００４４】
載置後、図１（ｄ）に示す第１回転工程では、スピンテーブル１０を４００ｒｐｍで第１の回転（Ｒ１（Ｘ）＝４００ｒｐｍ）を行い、紫外線硬化型接着剤３を振り切る。そしてスピンテーブル１０の回転を停止し有機複屈折膜５の位置ずれを観察し、有機複屈折膜５が図２（ａ）に示すように、透明基板１上で動いていた場合には、図２（ｂ）に示すように調整治具２０を用いて有機複屈折膜５の位置修正を行い、再度４００ｒｐｍで回転し、有機複屈折膜５が透明基板１上で位置ズレを起こさなくなるまで図１（ｄ）の工程を繰り返す。なお４００ｒｐｍでのＴ１（Ｘ）の総和は１０秒とした。
【００４５】
図１（ｅ）では、スピンテーブル１０を７００ｒｐｍで第１の回転（Ｒ１（Ｘ）＝７００ｒｐｍ）を行い、紫外線硬化型接着剤３を振り切る。そしてスピンテーブル１０の回転を停止し、有機複屈折膜５の位置ずれを観察し、有機複屈折膜５が透明基板１上で動いていた場合は調整治具２０を用いて有機複屈折膜５の位置修正を行い、再度７００ｒｐｍで回転し、有機複屈折膜５が透明基板１上で位置ズレを起こさなくなるまで図１（ｅ）の工程を繰り返す。なお７００ｒｐｍでのＴ１（Ｘ）の総和は３０秒とした。
【００４６】
図１（ｆ）では、スピンテーブルを９００ｒｐｍで第１の回転（Ｒ１（Ｘ）＝９００ｒｐｍ）を行い、紫外線硬化型接着剤３を振り切る。そしてスピンテーブル１０の回転を停止し有機複屈折膜５の位置ずれを観察し、有機複屈折膜５が透明基板１上で動いていた場合は調整治具２０を用いて有機複屈折膜５の位置修正を行い、再度９００ｒｐｍで回転し、有機複屈折膜が透明基板上で位置ズレを起こさなくなるまで図１（ｆ）の工程を繰り返す。なお９００ｒｐｍでのＴ１（Ｘ）の総和は９０秒とした。
【００４７】
図１（ｇ）では、その後スピンテーブルを回転（第２の回転、３ステップで回転数を４００ｒｐｍから９００ｒｐｍに上げ、９００ｒｐｍで３０秒間保持）し、紫外線硬化型接着剤３を振り切り、接着層厚さを面内で一定にする。また、第２の回転中に硬化前の紫外線硬化型接着剤３を溶解し、かつ有機複屈折膜５を溶解しない有機溶媒３１（本例ではイソプロピルアルコールを使用）を有機複屈折膜５と透明基板１の境界にリンス機構３０より滴下し、透明基板周辺の接着剤残を除去する。
【００４８】
図１（ｈ）では、スピンテーブル１０の回転を停止し、有機複屈折膜５側から、例えば図示しない高圧水銀灯を用いて紫外線ＵＶ（第１の紫外線）を照射し、紫外線硬化型接着剤３を硬化する。
【００４９】
上記の（ａ）〜（ｈ）の工程を実行し、３枚の透明基板１に対して有機複屈折膜５を接着したものを基板Ａ〜Ｃとする。なお３枚の基板Ａ、Ｂ、Ｃは、第１の回転Ｒ１（Ｘ）が等しい時の回転時間の総和が一定である。つまり４００ｒｐｍで１０秒、７００ｒｐｍで３０秒、９００ｒｐｍで９０秒回転させているが、３枚の基板間ではＴ１（Ｘ）自体は一致していない。
【００５０】
図１（ｉ）では、ダイシングソー１５を用いて前記の基板Ａ〜Ｃを切断し、２００倍の金属顕微鏡で断面を観察し、基板の直径方向での接着層厚さを測定（測定範囲：有機複屈折膜端から５〜１３０ｍｍ）した。直径方向での平均膜厚、最大値、最小値を図５に示す。基板Ａ〜Ｃにおいて、接着層の平均膜厚は２５〜２６μｍであり、実施例１の接着層厚さを加味しても、基板間での接着層の変動は数μｍ程度となり、接着層厚さの再現性が良いことが確認された。
【００５１】
実施例２の作製方法によれば、第１の回転によって有機複屈折膜５が透明基板１上で略動かなくなるまで第１回転工程と修正工程とを繰り返し、第１の回転が複数の回転数を有する場合，Ｘ回目の第１の回転の回転数をＲ１（Ｘ）［ｒｐｍ］、第２回転工程での第２の回転での最大の回転数をＲ２ｍａｘ［ｒｐｍ］すると、Ｒ２ｍａｘ＝Ｒ１（Ｘ）≧Ｒ１（Ｘ−１）≧・・・≧Ｒ１（１） 但しＸ≧２の関係になっている場合、Ｒ１（Ｘ）が等しい時の回転時間の総和を一定にすることによって基板間での接着層厚さの変動を抑制することができる。
【００５２】
上記の（ａ）〜（ｈ）と同じ工程で、３枚の透明基板１に対して有機複屈折膜５を接着し、実施例１と同様に有機複屈折膜３に回折格子を形成し、光学的に等方的なアクリル系紫外線硬化型接着剤（等方性接着剤）１１を用いて直径１６５ｍｍ、厚み１ｍｍの対向透明基板（材質：ショット製光学ガラスＢＫ７、裏面に反射防止膜あり）を接着し、ダイシングソー１５を用いて５ｍｍ角に切りだし、複数の偏光分離素子１００を完成させる。各基板の任意の５個の偏光分離素子について、回折効率を測定した結果、回折効率は略揃っていた。これは基板間で有機複屈折膜５を接着する接着層の膜厚変動が小さいためと予想される。
【００５３】
実施例３
図６を参照して実施例３の作成方法を説明する。図６（ａ）〜図６（ｋ）は、偏光分離素子の作製方法の工程を示すものである。
図６（ａ）では、直径１６５ｍｍ、厚さ１．５ｍｍのショット製光学ガラスＢＫ７からなる透明基板１をスピンテーブル１０に載せ、真空吸着によってスピンテーブル１０に固定する。その後スピンテーブル１０を１０〜５０ｒｐｍで回転させながら、透明基板１の中央部にディスペンサー１２を用いて屈折率１．５８、粘度：６００ｃｐのエポキシ系の紫外線硬化型接着剤３を８〜１２ｇ滴下した。滴下後、スピンテーブル１０を４００ｒｐｍで回転させ、図６（ｂ）に示すように、透明基板１全面に紫外線硬化型接着剤３を広げ、その後スピンテーブル１０の回転を停止する。図６（ａ）、図６（ｂ）は、透明基板１上に紫外線硬化型接着剤３を塗布する工程を示す。
【００５４】
図６（ｃ）において、スピンテーブル１０の回転停止後、広げられた紫外線硬化型接着剤３の上に、後述する載置装置を用いて透明基板１の直径よりも小径な、直径１５５ｍｍ、厚さ１００μｍの有機複屈折膜５を、その中心をスピンテーブル１０の回転中心に略合わせながら載置する。図６（ｃ）は、紫外線硬化型接着剤３上に有機複屈折膜５を載せるセット工程を示す。
【００５５】
図６（ｄ）に示すように、スピンテーブル１０を６００ｒｐｍで第１の回転（Ｒ１（1）＝６００ｒｐｍ、Ｔ１（１）＝８秒）を行い、紫外線硬化型接着剤３を振り切る。図６（ｄ）は、第１回転工程を示す。
【００５６】
図６（ｅ）において、スピンテーブル１０の回転を停止して有機複屈折膜５の位置ずれを観察したところ、図２（ａ）に示すように、有機複屈折膜５が透明基板１上で外側に１ｍｍ程度動いており、有機複屈折膜５の中心とスピンテーブル１０の回転中心が合わなくなっていた。そのため、調整治具２０を用いて有機複屈折膜５の外側にずれた側の端部を透明基板１の中心側へ押して、透明基板１上を滑動し、図２（ｂ）に示すように、有機複屈折膜５の位置修正を行った。つまり透明基板１と有機複屈折膜５の中心を合わせ、有機複屈折膜５が透明基板１からはみ出さない位置へ有機複屈折膜５を動かした。図６（ｅ）は修正工程を示す。
【００５７】
図６（ｆ）では、その後スピンテーブルを再度６００ｒｐｍで第１の回転（Ｒ１（２）＝６００ｒｐｍ、回転時間Ｔ１（２）＝２秒）を行い、接着剤を振り切る。その後スピンテーブル１０の回転を停止して有機複屈折膜５の位置ずれを観察したところ、有機複屈折膜５は透明基板１上でほとんど動いていなかった。
【００５８】
その後スピンテーブル１０を１０００ｒｐｍで第１の回転（Ｒ１（３）＝１０００ｒｐｍ、回転時間Ｔ１（３）＝５秒）を行い、接着剤を振り切る。その後スピンテーブル１０の回転を停止して有機複屈折膜５の位置ずれを観察したところ、有機複屈折膜５は透明基板１上で約２ｍｍ程度動いていた。その後調整治具２０を用い、有機複屈折膜５を透明基板１上で滑動し、有機複屈折膜５の位置修正を行った。
【００５９】
修正後、スピンテーブルを再度１０００ｒｐｍで第１の回転（Ｒ１（４）＝１０００ｒｐｍ、回転時間Ｔ１（４）＝６秒）を行い、紫外線硬化型接着剤３を振り切る。その後スピンテーブル１０の回転を停止して有機複屈折膜５の位置ずれを観察したところ、有機複屈折膜５は透明基板１上で約１ｍｍ程度動いていた。その後調整治具２０を用い、有機複屈折膜５を透明基板１上で滑動し、有機複屈折膜５の位置修正を行った。
【００６０】
修正後、スピンテーブル１０を再度１０００ｒｐｍで第１の回転（Ｒ１（５）＝１０００ｒｐｍ、回転時間Ｔ１（５）＝１０秒）を行い、紫外線硬化型接着剤３を振り切る。その後スピンテーブル１０の回転を停止して有機複屈折膜５の位置ずれを観察したところ、有機複屈折膜５は透明基板１上でほとんど動いていなかった。
【００６１】
観測後、スピンテーブル１０を再度１０００ｒｐｍで第１の回転（Ｒ１（６）＝１０００ｒｐｍ、回転時間Ｔ１（６）＝９秒）を行い、紫外線硬化型接着剤３を振り切る。その後スピンテーブル１０の回転を停止して有機複屈折膜５の位置ずれを観察したところ、有機複屈折膜５は透明基板１上でほとんど動いていなかった。
【００６２】
観測後、スピンテーブルを１５００ｒｐｍで第１の回転（Ｒ１（７）＝１５００ｒｐｍ、回転時間Ｔ１（７）＝２秒）を行い、紫外線硬化型接着剤３を振り切る。その後スピンテーブル１０の回転を停止して有機複屈折膜５の位置ずれを観察したところ、有機複屈折膜５は透明基板１上で約５ｍｍ程度動いていた。その後調整治具２０を用い、有機複屈折膜５を透明基板１上で滑動し、有機複屈折膜５の位置修正を行った。
【００６３】
修正後、スピンテーブル１０を再度１５００ｒｐｍで第１の回転（Ｒ１（８）＝１５００ｒｐｍ、回転時間Ｔ１（８）＝１６秒）を行い、紫外線硬化型接着剤３を振り切る。その後スピンテーブル１０の回転を停止して有機複屈折膜５の位置ずれを観察したところ、有機複屈折膜５は透明基板１上で約３ｍｍ程度動いていた。その後調整治具２０を用い、有機複屈折膜５を透明基板１上で滑動し、有機複屈折膜５の位置修正を行った。
【００６４】
修正後、スピンテーブル１０を再度１５００ｒｐｍで第１の回転（Ｒ１（９）＝１５００ｒｐｍ、回転時間Ｔ１（９）＝３０秒）を行い、接着剤を振り切る。その後スピンテーブルの回転を停止して有機複屈折膜の位置ずれを観察したところ、有機複屈折膜は透明基板上でほとんど動いていなかった。
【００６５】
観察後、スピンテーブルを再度１５００ｒｐｍで第１の回転（Ｒ１（１０）＝１５００ｒｐｍ、回転時間Ｔ１（１０）＝３２秒）を行い、紫外線硬化型接着剤３を振り切る。その後スピンテーブル１０の回転を停止して有機複屈折膜５の位置ずれを観察したところ、有機複屈折膜５は透明基板１上でほとんど動いていなかった。図７は、第１の回転の回転数と回転時間の推移を示す。
【００６６】
図６（ｇ）では、図６（ｆ）の終了後、スピンテーブル１０を回転（第２の回転、３ステップで回転数を６００ｒｐｍから１５００ｒｐｍに上げた。よってＲ２ｍａｘ［ｒｐｍ］は１５００ｒｐｍとなる）し、１５００ｒｐｍで５秒保持した後、１５００ｒｐｍで回転させながら有機複屈折膜５側から図示しないメタルハライドランプを用いて第２の紫外線ＵＶを照射し、紫外線硬化型接着剤３を徐々に半硬化する。なお、第２の紫外線照射のエネルギーは、第２の回転中に有機複屈折膜５が位置ずれを起こさない程度に紫外線硬化型接着剤３を半硬化できれば良いので、本例では実施例１で用いた第１の紫外線ＵＶの約３０％のエネルギーで照射した。図６（ｇ）は第２回転工程と半硬化工程を示す
第２の紫外線を照射している間に、完全硬化前の紫外線硬化型接着剤３を溶解し、かつ有機複屈折膜５を溶解しない有機溶媒３１（本例ではアセトンを使用）を有機複屈折膜５と透明基板１の境界にリンス機構３０より滴下し、透明基板周辺の接着剤残を除去した。
【００６７】
図６（ｈ）では、図６（ｇ）の工程終了後、スピンテーブル１０の回転を停止し、有機複屈折膜側から上記メタルハライドランプを用いて第１の紫外線ＵＶを照射し、紫外線硬化型接着剤３を完全に硬化する。図６（ｈ）は硬化工程を示す。以後、有機複屈折膜５が接着された透明基板１を基板６２と略す。
【００６８】
図６（ｉ）に示すように、作製された基板６２をスピンテーブル１０から外し、有機複屈折膜５上にポジレジストを１．５μｍの厚さに塗布し、６０℃、３０分のプリベークを行う。その後基板６０を縮小投影露光装置（ＮＡ＝０．５４、σ＝０．６、波長：ｉ線）に装着し、１０００周期ある１．０μｍのラインアンドスペースパターンのレチクルを用いて露光を行い、現像液ＮＭＤ−３を用いて現像を行い、１００℃、３０分のポストベークを行い、周期的なレジストパターンを完成させた。その後、前記のレジストパターンを１１０℃の雰囲気で１,１,３，３−テトラメチルヘキサジシラザン蒸気にさらし、レジスト表面に１,１,３，３−テトラメチルヘキサジシラザンをドープし、その後ＥＣＲエッチング装置を用いて酸素ガスを主成分とするエッチングガス雰囲気中で前記のレジストパターンをマスクとして有機複屈折膜を深さ４μｍエッチングした。その後剥離液を用いてレジストパターンを除去し、１０００周期ある凹凸状の格子となる回折格子６３を完成させた。
【００６９】
図６（ｊ）に示すように、平面加工したφ２００ｍｍ、厚み５０ｍｍのステンレス台上に回折格子６３を形成した基板６２を置き、回折格子６２面に光学的に等方的なエポキシ系紫外線硬化型接着剤（等方性接着剤）１１をマイクロシリンジで１．２ｍｌ滴下した。そして両面を光学研磨した直径１６５ｍｍ、厚み１ｍｍの対向透明基板９（材質：ショット製光学ガラスＢＫ７）を前記の等方性接着剤１１を塗布した基板面に載せ、さらに対向透明基板上に光学研磨した光学ガラスを載せ、対向透明基板に１００ｇｆ／ｃｍ２の圧力を加え、等方性接着剤１１を被接着面全面に広げた。なお、対向透明基板９の被接着面と対向する面となる自由表面（空気と接する面）には、入射光の反射が最小となるよう反射防止膜（図示せず）を形成しておく。この状態で対向透明基板を通して紫外光を照射し、等方性接着剤１１を硬化する。図６（ｊ）において、符号１Ｂは、このようにして対向透明基板１１を一体化した中間完成体を示す。
【００７０】
図６（ｋ）に示すように、中間完成体１Ｂに含まれている数１００個の回折格子６３を、ダイシングソー１５を用いて５ｍｍ角（各々が、１個の回折格子を有する）」に切りだし、複数個の偏光分離素子１０１を完成させる。
【００７１】
図６（ａ）〜図６（ｈ）の工程によって有機複屈折膜を接着した透明基板１をダイシングソー１５で切断し、２００倍の金属顕微鏡で断面を観察し、基板の直径方向での接着層厚さを測定（測定範囲：有機複屈折膜端から５〜１３０ｍｍ）した結果を図８に示す。本条件での接着層厚さは平均３２μｍであり、直径方向でも略均一であることが確認された。
【００７２】
実施例３の作製方法によれば、第１の回転によって有機複屈折膜５が透明基板１上で略動かなくなるまで、第１回転工程と修正工程とを繰り返し、その後、第２回転工程、半硬化工程、硬化工程を行うので、実施例１と同様に透明基板１からの有機複屈折膜５のはみ出しを防止することができる。さらに図６（ｇ）に示すように、第２の回転を行いながら、第２の紫外線ＵＶを照射して有機複屈折膜５を接着する紫外線硬化型接着剤３を半硬化させて高粘度化させるので、第２の回転中に透明基板１から有機複屈折膜５がはみ出すことをより確実に防止することができる。
【００７３】
第１回転工程と修正工程とを繰り返し、かつ第１の回転が複数の回転数を有する場合、Ｘ回目の第１の回転の回転数をＲ１（Ｘ）［ｒｐｍ］、第２回転工程での第２の回転での最大の回転数をＲ２ｍａｘ［ｒｐｍ］すると、
Ｒ２ｍａｘ＝Ｒ１（Ｘ）≧Ｒ１（Ｘ−１）≧・・・≧ Ｒ１（１） 但しＸ≧２の関係になっているので、第１回転工程と修正工程とを繰り返す毎に回転数が増加し、最終的には第１の回転の回転数は第２の回転の最大値、つまりＲ２ｍａｘに一致する。本実施例では、第１の回転の回転数が第２の回転の最大値（Ｒ２ｍａｘ）に一致した時も、有機複屈折膜５が透明基板１上で略動かなくなるまで第１回転工程と修正工程とを繰り返し、かつ第２の回転中に第２の紫外線を照射して紫外線硬化型接着剤を半硬化して高粘度化させている。このため、第１の回転を行った後、第２の回転を実施しても有機複屈折膜５は透明基板１上でより動かなくなり、透明基板１の中心と有機複屈折膜５の中心が略一致した状態に保たれる。このため、有機複屈折膜５の端部と透明基板１の端部の距離を小さく、すなわち、有機複屈折膜５の直径と透明基板１の直径の差を小さくすることができる。この結果、透明基板１上で偏光分離素子１００を形成できる面積を大きくでき、１枚の透明基板１から取れる偏光分離素子１００を多くできる。加えて上記の工程を取ると、図８に示したように有機複屈折膜５を接着する接着層厚さを面内で略均一にすることができる。
【００７４】
実施例４
本発明の実施例４の作成方法を説明する。
図６（ａ）直径１６５ｍｍ、厚さ１．５ｍｍのショット製光学ガラスＢＫ７からなる透明基板１をスピンテーブル１０に載せ、真空吸着によってスピンテーブル１０に固定した。その後スピンテーブル１０を１０〜５０ｒｐｍで回転させながら、透明基板１の中央部にディスペンサー１２を用いて屈折率１．５８、粘度：６００ｃｐのエポキシ系紫外線硬化型接着剤３を８〜１２ｇ滴下した。滴下後スピンテーブル１０を４００ｒｐｍで回転させ、図６（ｂ）に示すように、透明基板１全面に紫外線硬化型接着剤３を広げ、その後スピンテーブル１０の回転を停止する。
【００７５】
図６（ｃ）では、有機複屈折膜５の中心をスピンテーブル１０の回転中心に略合わせながら、後述の載置装置を用いて紫外線硬化型接着剤３の上に、直径１５５ｍｍ、厚さ９０μｍの有機複屈折膜５を載せる。
【００７６】
図６（ｄ）では、載置後、スピンテーブル１０を６００ｒｐｍで第１の回転（Ｒ１（Ｘ）＝６００ｒｐｍ）を行い、紫外線硬化型接着剤３を振り切る。そしてスピンテーブル１０の回転を停止し有機複屈折膜５の位置ずれを観察し、有機複屈折膜５が透明基板１上で動いていた場合は調整治具２０を用いて有機複屈折膜５の位置修正を行い、再度６００ｒｐｍで回転し、有機複屈折膜５が透明基板１上で位置ズレを起こさなくなるまで図６（ｄ）に示す工程を繰り返す。なお６００ｒｐｍでのＴ１（Ｘ）の総和は１０秒とした。
【００７７】
図６（ｅ）では、図６（ｄ）の工程後、スピンテーブル１０を１０００ｒｐｍで第１の回転（Ｒ１（Ｘ）＝１０００ｒｐｍ）を行い、紫外線硬化型接着剤３を振り切る。そしてスピンテーブル１０の回転を停止し有機複屈折膜５の位置ずれを観察し、有機複屈折膜５が透明基板１上で動いていた場合は調整治具２０を用いて有機複屈折膜５の位置修正を行い、再度１０００ｒｐｍで回転し、有機複屈折膜５が透明基板１上で位置ズレを起こさなくなるまで図６（ｅ）の工程を繰り返す。なお１０００ｒｐｍでのＴ１（Ｘ）の総和は３０秒とした。
【００７８】
図６（ｆ）では、さらにスピンテーブル１０を１５００ｒｐｍで第１の回転（Ｒ１（Ｘ）＝１５００ｒｐｍ）を行い、紫外線硬化型接着剤３を振り切る。そしてスピンテーブル１０の回転を停止し有機複屈折膜５の位置ずれを観察し、有機複屈折膜５が透明基板１上で動いていた場合は調整治具２０を用いて有機複屈折膜の位置修正を行い、再度１５００ｒｐｍで回転し、有機複屈折膜５が透明基板１上で位置ズレを起こさなくなるまで図６（ｆ）の工程を繰り返す。なお１５００ｒｐｍでのＴ１（Ｘ）の総和は８０秒とした。
【００７９】
図６（ｇ）では、図６（ｆ）の工程後、スピンテーブル１０を回転（第２の回転、３ステップで回転数を６００ｒｐｍから１５００ｒｐｍに上げた。よってＲ２ｍａｘ［ｒｐｍ］は１５００ｒｐｍとなる）し、１５００ｒｐｍで５秒保持した後、１５００ｒｐｍで回転させながら有機複屈折膜５側から図示しないメタルハライドランプを用いて第２の紫外線ＵＶを照射し、紫外線硬化型接着剤３を徐々に半硬化させた。なお第２の紫外線照射のエネルギーは、実施例３と同様に実施例１で用いた第１の紫外線の約３０％のエネルギーで照射した。また第２の紫外線を照射している間に、完全硬化前の紫外線硬化型接着剤３を溶解し、かつ有機複屈折膜５を溶解しない有機溶媒３１（本例ではアセトンを使用）を有機複屈折膜５と透明基板１の境界にリンス機構３０より滴下し、透明基板周辺の接着剤残を除去した。
【００８０】
図６（ｈ）では、半硬化工程後、スピンテーブル１０の回転を停止し、有機複屈折膜５側からメタルハライドランプを用いて第１の紫外線を照射し、紫外線硬化型接着剤３を完全に硬化させた。
【００８１】
図６（ａ）〜図６（ｈ）の工程を行い、３枚の透明基板１に対して有機複屈折膜５を接着した基板Ｄ〜Ｆを作製した。この３枚の基板Ｄ〜Ｆは、第１の回転Ｒ１（Ｘ）が等しい時の回転時間の総和が一定である。つまり６００ｒｐｍで１０秒、１０００ｒｐｍで３０秒、１５００ｒｐｍで８０秒回転させているが、３枚の基板間ではＴ１（Ｘ）自体は一致していない。
【００８２】
図６（ｉ）では、硬化後ダイシングソー１０を用いて前記の基板Ｄ〜Ｆを切断し、２００倍の金属顕微鏡で断面を観察し、基板の直径方向での接着層厚さを測定（測定範囲：有機複屈折膜端から５〜１３０ｍｍ）した。直径方向での平均膜厚、最大値、最小値を図９に示す。基板Ｄ〜Ｆにおいて、接着層の平均膜厚は３２〜３３μｍであり、実施例２と同様に基板間での紫外線硬化型接着剤３の変動は数μｍ程度であった。
【００８３】
実施例４の作製方法によれば、透明基板１上に入射光の異なる振動面に対して屈折率が異なる有機複屈折膜５を接着工程が、上記の工程からなり、第１の回転によって有機複屈折膜５が透明基板１上で略動かなくなるまで、第１回転工程と修正工程とを繰り返し、かつ第１の回転が複数の回転数を有する場合、Ｘ回目の第１の回転の回転数をＲ１（Ｘ）［ｒｐｍ］、第２回転工程での第２の回転での最大の回転数をＲ２ｍａｘ［ｒｐｍ］すると、
Ｒ２ｍａｘ＝Ｒ１（Ｘ）≧Ｒ１（Ｘ−１）≧・・・≧ Ｒ１（１） 但しＸ≧２の関係になっている場合、Ｒ１（Ｘ）が等しい時の回転時間の総和を一定にすることによって複数の基板間での接着層厚さの変動を抑制することができる。また図６（ａ）〜図６（ｈ）と同じ工程で、３枚の透明基板に対して有機複屈折膜５を接着し、実施例３と同様に有機複屈折膜５に回折格子６３を形成し、光学的に等方的なエポキシ系紫外線硬化型接着剤（等方性接着剤）１１を用いて直径１６５ｍｍ、厚み１ｍｍの対向透明基板（材質：ショット製光学ガラスＢＫ７、裏面に反射防止膜あり）を接着し、図６（ｋ）に示すダイシングソー１５を用いて５ｍｍ角に切りだし、複数の偏光分離素子１０１を完成させた。各基板の任意の５個の偏光分離素子１０１について回折効率を測定した結果、回折効率は略均一であった。これは各基板間で有機複屈折膜を接着する接着層の膜厚が均一であるためと予想される。
【００８４】
実施例１〜４において、透明基板１に紫外線硬化型接着剤３を塗布する方法は、透明基板１を回転しながらディスペンサー１２から紫外線硬化型接着剤３を滴下し、その後回転数を上げて均一な塗布厚さを得る方法を採用しているが、スピンテーブル１０を停止してディスペンサー１２から紫外線硬化型接着剤３を滴下し、その後透明基板１、すなわち、スピンテーブル１０を回転させて紫外線硬化型接着剤３を透明基板全面に広げても良い。また、本発明は上記の塗布方法に限定される必要は無く、均一な塗布厚さが得られる方法であれば何ら構わず、例えばスプレー法やロールコート法を用いることでも無論構わない。
【００８５】
実施例５
図１０は、本発明の光ピックアップ装置の一構成例を示す。図１０に示すＣＤ−ＲＷ用の光ピックアップ装置２００は、ＣＤからの情報の読み取りと、ＣＤ−ＲＷに対する情報の書き込みと情報の読み取りを行うものである。光ピックアップ装置では、レーザーダイオード８１から出射された波長７８０ｎｍの光は実施例１の偏光分離素子１００とコリメータレンズ８５、λ／４波長板８６、対物レンズ８７を通った後、ＣＤ−ＲＷ９０を照射する。照射された光は、ＣＤ−ＲＷ９０の記録ピットで反射され、その反射光はλ／４波長板８６で直線偏光になった後、偏光分離素子８３で回折してフォトダイオード８９に導かれ、フォーカス検出、トラック検出、信号検出が行われる。
【００８６】
本実施例の光ピックアップ装置を用い、ＣＤ−ＲＷ９０に信号を記録し、その後同じ光ピックアップ装置で信号の再生を行った所、プリズムを接着したビームスプリッタとλ／4波長板を組み合わせた従来のＣＤ−ＲＷ用の光ピックアップ装置と同等の再生信号出力を得ることができ、本実施例の光ピックアップ装置が従来の光ピックアップ装置と同等の記録／再生特性を持つことが確認できた。また本実施例のピックアップ装置では、偏光分離素子１００がプリズムを接着したビームスプリッタよりも小さくなっており、従来の光ピックアップ装置と比較して小型化が実現できた。
【００８７】
実施例６
図１１は、本発明の光ピックアップ装置の別な構成例を示す。図１１に示すＤＶＤ用の光ピックアップ装置３００は、ＣＤからの情報の読み取りと、ＤＶＤ−ＲＯＭ９１に対する情報の読み取りを行うものである。ＤＶＤ用の光ピックアッ装置では、レーザーダイオード８２から出射された波長６８０ｎｍの光は実施例３の偏光分離素子１０１とコリメータレンズ８５、λ／４波長板８６、対物レンズ８７を通った後、ＤＶＤ−ＲＯＭ９１を照射する。ＤＶＤ−ＲＯＭ９１の記録ピットからの反射光はλ／４波長板８６で直線偏光になった後、偏光分離素子１０１で回折してフォトダイオード８９に導かれ、フォーカス検出、トラック検出、信号検出が行われる。
【００８８】
本実施例の光ピックアップ装置を用い、ＤＶＤ−ＲＯＭ９１から情報信号の再生を行った所、プリズムを接着したビームスプリッタとλ／４波長板を組み合わせた従来のＤＶＤ用の光ピックアップ装置と同等の信号出力を得ることができ、本例の光ピックアップ装置が従来の光ピックアップ装置と同等の再生特性を持つことが確認できた。また、本実施例の光ピックアップ装置では、偏光分離素子１０１がプリズムを接着したビームスプリッタよりも小さくなっているため、従来の光ピックアップ装置よりも小型化となった。
【００８９】
実施例７
図１２は、本発明の有機複屈折膜の接着装置の一例を示す。この接着装置４００は、透明基板１を保持するスピンテーブル１０、スピンテーブル１０を回転させるステッピングモーター７１と図示しない駆動伝達機構を有する回転機構７０、透明基板１に紫外線硬化型接着剤３を塗布する塗布機構としてのディスペンサー１２、２本の吸着アーム５０，５０によって有機複屈折膜５の両端を吸着保持し、透明基板１上に塗布された紫外線硬化型接着剤３上に有機複屈折膜５を載置する載置機構５５、有機複屈折膜５を透明基板１上で滑動して位置を修正する位置調整機構４０、硬化前の紫外線硬化型接着剤を溶解しかつ有機複屈折膜を溶解しない有機溶媒（図１、図６参照）を透明基板１に滴下するリンス機構３０、透明基板１に紫外線を照射する高圧水銀灯やメタルハライドランプ等からなる紫外線照射機構６０等から構成されている。位置調整機構４４は、Ｘ、Ｙ方向に可動できる２軸アーム４１の先端に調整治具２０が装着されていて、この調整治具２０を用いて実施例１〜４で説明したように有機複屈折膜５を押し、透明基板１上を滑らせる機構になっている。
【００９０】
本実施例の接着装置を用いて有機複屈折膜５を接着する手順を次に説明する。直径１６５ｍｍ、厚さ１．５ｍｍのショット製光学ガラスＢＫ７からなる透明基板１をスピンテーブル１０に載せ、真空吸着によってスピンテーブル１０に固定する。その後透明基板１の中央部にロボットアーム３１によってディスペンサー１２を移動し、スピンテーブル１０を２０ｒｐｍで回転させながら、透明基板１の中央部にディスペンサー１２を用いて屈折率１．５２、粘度５００ｃｐのアクリル系紫外線硬化型接着剤３を１０g滴下する。
【００９１】
その後ディスペンサー１２を図に示す元の位置に戻し、スピンテーブル１０を３００ｒｐｍで回転させ、透明基板１全面に紫外線硬化型接着剤３を広げ、その後スピンテーブル１０の回転を停止する。その後直径１５５ｍｍ、厚さ８０μｍの有機複屈折膜５の両端を載置機構５５の２本の吸着アーム５０，５０に真空吸着して保持し、載置機構５５を透明基板１上へ移動し、有機複屈折膜５の中心をスピンテーブル１０の回転中心に略合わせながら２本の吸着アーム５０，５０の真空吸着を徐々に解除して、透明基板全面に広げられた紫外線硬化型接着剤３の上に有機複屈折膜５を載せる。
【００９２】
その後載置装置５５を図に示す元の位置に戻し、スピンテーブル１０を４００ｒｐｍで回転（第１の回転）させ、紫外線硬化型接着剤３を振り切る。その後スピンテーブル１０の回転を停止し、２軸アーム４１を動かして調整治具２０を有機複屈折膜５の側面に突き当て、有機複屈折膜５の位置ズレに応じて２軸アームをＸ，Ｙ方向に動かし、調整治具２０で有機複屈折膜５を押して透明基板１上で滑動し、有機複屈折膜５の位置修正を行う。
【００９３】
位置調整終了後、２軸アーム４１を元の位置に戻し、再度透明基板１を４００ｒｐｍで回転（第１の回転）し、第１の回転によって有機複屈折膜５が透明基板１上で動かなくなるまで上記の操作を繰り返す。その後スピンテーブル１０を７００ｒｐｍで回転（第１の回転）させ、紫外線硬化型接着剤３を振り切る。
【００９４】
その後スピンテーブル１０の回転を停止し、２軸アーム４１を動かして調整治具２０を有機複屈折膜５の側面に突き当て、有機複屈折膜５の位置ズレに応じて２軸アーム４１をＸ，Ｙ方向に動かし有機複屈折膜５を調整治具２０で押し、有機複屈折膜５を透明基板１上で滑動して有機複屈折膜５の位置修正を行う。
【００９５】
位置調整終了後、２軸アーム４１を図に示す元の位置に戻し、再度透明基板１を７００ｒｐｍで回転（第１の回転）し、第１の回転によって有機複屈折膜５が透明基板１上で動かなくなるまで上記の操作を繰り返す。その後スピンテーブルを９００ｒｐｍで回転（第１の回転）させ、紫外線硬化型接着剤３を振り切る。
【００９６】
その後スピンテーブル１０の回転を停止し、２軸アーム４１を動かして調整治具２０を有機複屈折膜５の側面に突き当て、有機複屈折膜５の位置ズレに応じて２軸アーム４１をＸ，Ｙ方向に動かし有機複屈折膜５を調整治具２０で押し、有機複屈折膜５を透明基板１上で滑動して、その位置修正を行う。位置調整終了後、２軸アーム４１を図に示す元の位置に戻し、再度、透明基板１を９００ｒｐｍで回転（第１の回転）し、第１の回転によって有機複屈折膜５が透明基板１上で動かなくなるまで上記の操作を繰り返す。
【００９７】
その後第２の回転（３ステップで４００ｒｐｍから９００ｒｐｍに回転数を上げる）を行い、紫外線硬化型接着剤３を振り切り、接着層厚さを面内で一定にする。また、第２の回転中に有機複屈折膜上にリンス機構３０を移動して、硬化前の紫外線硬化型接着剤３を溶解しかつ有機複屈折膜５を溶解しない有機溶媒（本例ではイソプロピルアルコールを使用）を滴下し、基板周辺部に残っていた紫外線硬化型接着剤を除去する。
【００９８】
その後スピンテーブル１０の回転を停止し、リンス機構３０を元の位置に戻す。そして透明基板１上に紫外線照射機構６０を移動し、有機複屈折膜５側、すなわち本例では紙面垂直方向から第１の紫外線を照射して紫外線硬化型接着剤３を硬化させる。紫外線照射終了後、紫外線照射機構６０を図に示す元の位置に戻し、スピンテーブル１０の真空吸着を解除して有機複屈折膜５を接着した透明基板１を取り出す。
【００９９】
図１２に示すような構成の接着装置を用いると、実施例１、２の偏光分離素子１００の作製方法を実現できるため、透明基板１からの有機複屈折膜５のはみ出しを防止できる。またリンス機構３０から硬化前の紫外線硬化型接着剤３を溶解し、かつ有機複屈折膜５を溶解しない有機溶媒を滴下するため、基板周辺部に残っていた紫外線硬化型接着剤３を除去できる。
【０１００】
また、第１の回転Ｒ１（Ｘ）が複数個の回転数を有する場合、Ｒ１（Ｘ）が等しい時の回転時間の総和を一定にすることによって、実施例３の偏光分離素子１０１の作製方法を実現できることから、基板間での接着層厚さの変動（バラツキ）を抑えることができる。
【０１０１】
本例では第２の回転の終了後に第１の紫外線を照射して紫外線硬化型接着剤を硬化したが、第２の回転中に透明基板１上に紫外線照射機構６０を移動し、有機複屈折膜５側から第２の紫外線を照射して紫外線硬化型接着剤３を半硬化させ、その後スピンテーブ１０ルの回転を停止し、リンス機構３０を元の位置に戻し、さらに紫外線照射機構６０から有機複屈折膜５側から第１の紫外線を照射して紫外線硬化型接着剤３を硬化させると、実施例３、４の偏光分離素子の作製方法を実現できるため、透明基板１からの有機複屈折膜５のはみ出しや位置ズレをより確実に抑制することができる。
【０１０２】
さらに第１の回転Ｒ１（Ｘ）が複数の回転数を有する場合、Ｒ１（Ｘ）が等しい時の回転時間の総和を一定にすることによって、実施例４の偏光分離素子の作製方法を実現できることから、基板間での接着層厚さの変動（バラツキ）を抑えることができる。
【０１０３】
本例では紫外線照射機構６０は１つであるため、第１、第２の紫外線照射では照射時間や照射距離等を変えて第１の紫外線と第２の紫外線を照射するが、光強度の異なる２つの紫外線照射機構を配設し、各々第１の紫外線と第２の紫外線を照射する構成であっても良い。
【０１０４】
【発明の効果】
本発明によれば、第１の回転によって有機複屈折膜が透明基板上で略動かなくなるまで第１回転工程と修正工程とを繰り返し、その後、第２回転工程及び硬化工程を行うことで、透明基板からの有機複屈折膜のはみ出しが抑制され、回折格子を形成するためのリソグラフィー／ドライエッチング工程等において、装置内や工程間の搬送で基板側面をクランプすることができ、搬送不良の発生を抑制することができる。
【０１０５】
本発明によれば、第１の回転によって有機複屈折膜が透明基板上で略動かなくなるまで第１回転工程と修正工程とを繰り返し、その後、第２回転工程、半硬化工程、硬化工程を行うことで、紫外線硬化型接着剤が第２の回転中に半硬化して高粘度化されるので、透明基板からの有機複屈折膜のはみ出しがさらに抑制され、回折格子を形成するためのリソグラフィー／ドライエッチング工程等において、装置内や工程間の搬送で基板側面をクランプすることができ、搬送不良の発生をより抑制することができる。
【０１０６】
本発明によれば、Ｘ回目の第１の回転の回転数をＲ１（Ｘ）［ｒｐｍ］、第２回転工程での第２の回転での最大の回転数をＲ２ｍａｘ［ｒｐｍ］すると、Ｒ２ｍａｘ＝Ｒ１（Ｘ）≧Ｒ１（Ｘ−１）≧・・・≧Ｒ１（１） 但しＸ≧２の関係としているので、第１回転工程と修正工程とを繰り返す毎に回転数が増加し、最終的には第１の回転の回転数は第２の回転の最大値、つまりＲ２ｍａｘと一致する。このため、第１の回転の回転数が第２の回転の最大値（Ｒ２ｍａｘ）に一致した時も、有機複屈折膜が透明基板上で略動かなくなるまで第１回転工程と修正工程とを繰り返すことで、第１の回転を行った後、第２の回転を実施するので有機複屈折膜は透明基板上で動きにくくなり、有機複屈折膜の端部と透明基板の端部の距離を小さくできる。このため、基板上での偏光分離素子を形成できる面積が大きくなり、１枚の基板から取れる偏光分離素子を多くすることができて生産効率がよくなるとともに、有機複屈折膜を接着する接着層厚さを面内で略均一にすることができる。また、半硬化工程を有する場合、紫外線硬化型接着剤の高粘度化により透明基板上で有機複屈折膜が動きにくくなるので、有機複屈折膜の端部と透明基板の端部の距離をさらに小さくでき、基板上で偏光分離素子を形成できる面積をより一層広くでき、１枚の基板から取れる偏光分離素子をさらに多くできて、生産効率がより良くなる。
【０１０７】
本発明によれば、第１回転工程と修正工程を繰り返し、かつＲ１（Ｘ）が複数の回転数を有する場合、Ｒ１（Ｘ）が等しい時の回転時間の総和を透明基板間で一定としているので、基板間において有機複屈折膜を接着する接着層厚さの変動を抑制することができる。
【０１０８】
本発明によれば、有機複屈折膜の接着工程で透明基板からの有機複屈折膜のはみ出しや位置ズレを抑制できるので、リソグラフィー／ドライエッチング工程等において、装置内や工程間の搬送で基板側面をクランプしても搬送不良が発生しにくいので、歩留が向上する。特に、Ｒ１（Ｘ）が複数の回転数を有する場合、Ｒ１（Ｘ）が等しい時の回転時間の総和を一定として作製した場合、基板間で接着層の厚さ変動が小さいので、個々の偏光分離素子間での回折効率を揃えることができる。
【０１０９】
本発明によれば、有機複屈折膜に回折格子を設けた偏光分離素子を光ピックアップ装置に用いることで、従来のプリズムを接着したビームスプリッタよりも小型化が可能なので、光ピックアップ装置の小型化を図ることができる。
【０１１０】
本発明によれば、上記効果を有する偏光分離素子の作製方法を実現できるので、有機複屈折膜の接着工程において透明基板からの有機複屈折膜のはみ出しや位置ズレを抑制することができる。
【図面の簡単な説明】
【図１】偏光分離素子の作製方法の一例を示す工程図である。
【図２】有機複屈折膜の位置ずれ状態と修正後の状態を示す斜視図である。
【図３】実施例１における第１の回転の回転数と回転時間の推移を示す図である。
【図４】実施例１での接着層の膜厚の変位状態を示す図である。
【図５】実施例２での接着層の膜厚の変化状態を示す図である。
【図６】偏光分離素子の作製方法の別な例を示す工程図である。
【図７】実施例３における第１の回転の回転数と回転時間の推移を示す図である。
【図８】実施例３での接着層の膜厚の変位状態を示す図である。
【図９】実施例４での接着層の膜厚の変位状態を示す図である。
【図１０】光ピックアップ装置の一例を示す図である。
【図１１】光ピックアップ装置の別な例を示す図である。
【図１２】有機複屈折膜の接着装置の一例を示す図である。
【図１３】従来の偏光分離素子の作製方法を示す工程図である。
【図１４】貼り合わせ光ディスクの作製方法を示す工程図である。
【符号の説明】
１ 透明基板
３ 紫外線硬化型接着剤
５ 有機複屈折膜
１０ スピンテーブル
１２ 塗布機構
４０ 位置調整機構
５５ 載置機構
６０ 紫外線照射機構
６１，６３ 凹凸による回折格子
７０ 回転機構
１００，１０１ 偏光分離素子
２００，３００ 光ピックアップ装置
４００ 接着装置[0001]
The present invention relates to a polarization separation element, a manufacturing method thereof, an adhesive device, and an optical pickup device.
[0002]
[Prior art]
In an optical pickup device for an optical disk, a polarization separation element is used to separate an incident light beam from a light source and a return light beam reflected by the optical disk and bearing information on the optical disk, and efficiently guide the return light beam to a light detection means. ing. A beam splitter with a prism attached as a polarization separation element is used together with a λ / 4 wavelength plate. To meet the demand for miniaturization and cost reduction of optical pickup devices, a birefringent diffraction grating type that can be thinned is used. Are intended for use.
[0003]
Japanese Patent Application Laid-Open No. 2000-7513 discloses an organic birefringent film having a refractive index different from that of a vibrating surface of incident light on a transparent substrate as a polarization separating element of this type, and a periodicity is formed on the surface of the organic birefringent film. In which a diffraction grating is formed by general irregularities. As the organic birefringent film, a stretched organic polymer film is used.
In this polarization separation element, the organic birefringent film is bonded to the transparent substrate using an adhesive, but in order to make the optical path length constant for the light beam transmitted through the diffraction grating, the thickness of the adhesive layer To make the surface of the organic birefringent film flat. In addition, if bubbles enter the adhesive layer, the incident / emitted light flux is scattered by the bubbles and the diffraction efficiency is lowered. Therefore, an adhesion method that does not involve the bubbles is required.
[0004]
As an example of a method for adhering an organic birefringent film to a transparent substrate, there is a spinner method used in a bonded optical disk. A manufacturing process of a bonded optical disk by the spinner method will be described with reference to FIGS. As shown in FIG. 13A, the hub 202 formed on the first substrate 201 is inserted into the center pin 203 of the spin table 10, and the dispenser 12 is applied to the first substrate 201 while rotating the spin table 10. The ultraviolet curable adhesive 3 is dropped. As shown in FIG. 13B, when the UV curable adhesive 3 spreads over the entire surface of the first substrate 201, the rotation of the spin table 10 is stopped, and as shown in FIG. The hub 205 formed on 204 is inserted into the center pin 203 of the spin table 10 to bring the first substrate 201 and the second substrate 204 into contact with each other. Next, as shown in FIG. 13 (d), the spin table 10 on which the first substrate 201 and the second substrate 204 are placed is rotated, and the excess UV curable adhesive 3 is spun off and the thickness of the adhesive layer is increased. Then, as shown in FIG. 13E, the rotation of the spin table 10 is stopped, and the ultraviolet curable adhesive layer 3 is cured by irradiating ultraviolet rays (UV) to complete the bonded optical disk.
[0005]
When applying a spinner method to the adhesion of an organic birefringent film to produce a polarized light separating element having a size of about several millimeters, a few on the organic birefringent film bonded to a transparent substrate having a diameter of 4 to 8 inches. It is conceivable to form 10 to several hundred diffraction gratings in an array and then take out individual polarization separation elements by dicing. In order to increase the number of polarized light separating elements that can be taken from one substrate, it is preferable not to provide a hub for the organic birefringent film or transparent substrate and a center pin for the spin table 10. For example, as shown in FIG. 14 (a), the transparent substrate 1 is vacuum-sucked on a spin table 10 without a center pin, and thereafter, an ultraviolet curable adhesive 3 is dropped on the center of the transparent substrate 1. It can be considered that the organic birefringent film 5 is placed on the transparent substrate 1 after rotating and spreading the ultraviolet curable adhesive 3 over the entire dropping surface of the transparent substrate 1.
[0006]
[Problems to be solved by the invention]
In the method of manufacturing the polarization separation element shown in FIG. 14, since the organic birefringent film 5 has no hub and the spin table 10 has no center pin, the organic birefringent film 5 is not fixed on the spin table 10 and is free. Will ride on a transparent substrate. When the organic birefringent film 5 is placed on the transparent substrate 1 coated with the ultraviolet curable adhesive 3, a mounting device is generally used, but the center of the organic birefringent film 5 is accurately set to the rotation center of the spin table 10. Matching is often difficult from the standpoint of mechanical accuracy of the mounting device. When the organic birefringent film 5 is not on the rotation center of the spin table 10, when the spin table 10 is rotated, the organic birefringent film 5 is displaced with respect to the transparent substrate 1 as shown in FIG. Will be caused. When this positional deviation is large, the organic birefringent film 5 protrudes from the transparent substrate 1.
[0007]
After the ultraviolet curable adhesive 3 is cured by ultraviolet irradiation, lithography / dry etching is performed to form a diffraction grating, but the side surface of the transparent substrate 1 is clamped from the side during conveyance in the apparatus or between processes. In many cases, if the organic birefringent film 3 protrudes from the transparent substrate 1, it cannot be clamped and transport becomes difficult, and a diffraction grating cannot be formed.
[0008]
In order to prevent the displacement of the organic birefringent film 5 during rotation of the spin table 10, a method of irradiating ultraviolet rays during rotation can be considered. For example, in the method for producing a bonded optical disk described in JP-A-10-334521 and JP-A-2000-268416, a method for curing an ultraviolet curable adhesive by irradiating ultraviolet rays during rotation has been proposed. Yes. However, in the production of the polarization separation element, it is difficult to completely prevent the misalignment of the organic birefringent film because the substrate must be rotated to some extent in order to make the thickness of the adhesive layer uniform and then irradiated with ultraviolet rays. there were.
[0009]
An image recognition function using a CCD or the like is mounted on a mounting device for mounting the organic birefringent film 5 on a transparent substrate, and the rotation center of the spin table 10 and the center of the organic birefringent film 5 are detected, and the mounting device When the center of the organic birefringent film is placed at the center of rotation of the spin table while applying feedback control, the alignment accuracy between the center of rotation of the spin table and the center of the organic birefringent film can be significantly improved. Misalignment of the organic birefringent film is less likely to occur inside. However, it is necessary to provide an image recognition function and a feedback mechanism in the mounting device, which increases the cost of the mounting device. Further, since position detection and feedback control are performed at the time of bonding, the throughput of the bonding process is lowered, and it becomes difficult to manufacture a polarization separation element at low cost.
[0010]
An object of the present invention is to provide a method and an apparatus for manufacturing a polarization separation element that suppresses the protrusion and displacement of an organic birefringent film from the transparent substrate when the organic birefringent film is bonded to the transparent substrate.
An object of the present invention is to provide a method for manufacturing a polarization separation element that reduces variations in the thickness of an adhesive layer between substrates, and a polarization separation element that can improve yield and achieve uniform diffraction efficiency between individual elements. And
SUMMARY OF THE INVENTION An object of the present invention is to provide an optical pickup device that can be made smaller than a conventional structure.
[0011]
[Means for Solving the Problems]
The method for producing a polarization separation element of the present invention includes an adhesion step of adhering an organic birefringent film having a different refractive index to a vibration surface having different incident light on a transparent substrate, and a periodic mask on the organic birefringent film. Forming a pattern, and etching the organic birefringent film using this mask pattern to form a diffraction grating having periodic irregularities, and is characterized by the following.
[0012]
In claim 1, the bonding step includes a step of applying an ultraviolet curable adhesive on a transparent substrate, a setting step of placing an organic birefringent film on the ultraviolet curable adhesive, and a transparent substrate on which the organic birefringent film is placed. A first rotation process that rotates in the first rotation, a correction process that stops the rotation of the transparent substrate that rotates in the first rotation and slides the organic birefringent film on the transparent substrate to correct the position; A second rotation process that rotates by rotating the second rotation, a curing process that stops the rotation of the transparent substrate that rotates by the second rotation, and cures the ultraviolet curable adhesive by irradiating ultraviolet rays. The first rotation process and the correction process are repeated until the refractive film does not substantially move on the transparent substrate, and then the second rotation process and the curing process are performed.
[0013]
According to a fourth aspect of the present invention, the bonding step includes a step of applying an ultraviolet curable adhesive on a transparent substrate, a setting step of placing an organic birefringent film on the ultraviolet curable adhesive, and a transparent substrate on which the organic birefringent film is placed. A first rotation process that rotates in the first rotation, a correction process that stops the rotation of the transparent substrate that rotates in the first rotation and slides the organic birefringent film on the transparent substrate to correct the position; The second rotation process that rotates with the rotation, the semi-curing process that irradiates ultraviolet rays during the second rotation process and semi-cures the UV-curable adhesive, the rotation of the transparent substrate that rotates with the second rotation is stopped, and the ultraviolet light And curing the ultraviolet curable adhesive by repeating the first rotation process and the correction process until the organic birefringent film substantially does not move on the transparent substrate by the first rotation, Perform two-rotation process, semi-curing process, curing process It is characterized.
[0014]
In the second and fifth aspects, when the first rotation process and the correction process are repeated and the rotation of the transparent substrate in the first rotation process has a plurality of rotation speeds, the rotation speed of the first rotation of the Xth time is R1 ( X) [rpm], R2max = R1 (X) ≧ R1 (X−1) ≧...> R1 (1) when the maximum number of rotations of the second rotation in the second rotation step is R2max [rpm]. However, it is characterized by the relationship of X ≧ 2.
[0015]
In Claims 3 and 6, when the first rotation process and the correction process are repeated and R1 (X) has a plurality of rotation speeds, the total rotation time when R1 (X) is equal is Between transparent substrates It is characterized by being constant.
[0017]
The organic birefringent film bonding apparatus of the present invention includes a spin table that holds a transparent substrate, a rotation mechanism that rotates the spin table, a coating mechanism that applies an ultraviolet curable adhesive to the transparent substrate held by the spin table, A mounting mechanism for placing an organic birefringent film on an ultraviolet curable adhesive applied on a transparent substrate, an ultraviolet irradiation mechanism for irradiating the ultraviolet curable adhesive with ultraviolet light through the organic birefringent film, and transparent It has a position adjusting mechanism for correcting the position by sliding the organic birefringent film placed on the substrate on the transparent substrate.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of a method for manufacturing a polarization separation element will be described with reference to some specific examples. The polarization separating element is manufactured by adhering an organic birefringent film having a different refractive index to a vibrating surface of incident light on a transparent substrate, and a periodic mask pattern on the organic birefringent film. And forming a diffraction grating with periodic irregularities by etching the organic birefringent film using this mask pattern.
[0019]
【Example】
Example 1
A creation method of the first embodiment will be described with reference to FIG. FIG. 1A to FIG. 1K show steps of a method for manufacturing a polarization separation element. In FIG. 1A, a transparent substrate 1 made of shot optical glass BK7 having a diameter of 165 mm and a thickness of 1.5 mm is placed on a spin table 10 and fixed to the spin table 10 by vacuum suction, and the spin table 10 is rotated at 10 to 50 rpm. 8 to 11 g of acrylic ultraviolet curable adhesive 3 having a refractive index of 1.52 and a viscosity of 500 cp is dropped onto the center of the transparent substrate 1 using the dispenser 12. After the dropping, the spin table 10 is rotated at 300 rpm, and as shown in FIG. 1B, the ultraviolet curable adhesive 3 is spread over the entire dropping surface of the transparent substrate 1, and then the rotation of the spin table 10 is stopped. FIG. 1A and FIG. 1B show a process of applying an ultraviolet curable adhesive 3 on the transparent substrate 1.
[0020]
In FIG. 1C, after the rotation of the spin table 10 is stopped, a diameter 155 mm, a thickness smaller than the diameter of the transparent substrate 1 is placed on the spread UV curable adhesive 3 using a mounting device described later. An organic birefringent film 5 having a thickness of 80 μm is placed with its center approximately aligned with the rotation center of the spin table 10. FIG. 1C shows a setting process for placing the organic birefringent film 5 on the ultraviolet curable adhesive 3.
[0021]
After the placement, as shown in FIG. 1D, the spin table 10 is rotated at 400 rpm for the first time, and the ultraviolet curable adhesive 3 is shaken off. Here, assuming that the rotation speed of the first rotation of the Xth time is R1 (X) [rpm], and the rotation time of the first rotation of the Xth time is T1 (X), R1 (1) = 400 rpm, T1 (1 ) = 3 seconds. FIG.1 (d) shows a 1st rotation process.
[0022]
In FIG. 1E, when the rotation of the spin table 10 is stopped and the displacement of the organic birefringent film 5 is observed, the organic birefringent film 5 is formed on the transparent substrate 1 as shown in FIG. It moved about 5 mm outward, and the center of the organic birefringent film 5 and the rotation center of the spin table 10 were not aligned. Therefore, the adjustment jig 20 is used to push the end of the organic birefringent film 5 on the outer side to the center side of the transparent substrate 1 and to move the organic birefringent film 5 so as to slide on the transparent substrate 1 (hereinafter referred to as “sliding”). The movement of the organic birefringent film 5 was corrected as shown in FIG. 2B. That is, the centers of the transparent substrate 1 and the organic birefringent film 5 are aligned, and the organic birefringent film 5 is moved to a position where the organic birefringent film 5 does not protrude from the transparent substrate 1. FIG. 1 (e) shows the correction process.
[0023]
After such a correction process, as shown in FIG. 1 (f), the spin table 10 is again rotated at 400 rpm for the first rotation (R1 (2) = 400 rpm, rotation time T1 (2) = 7 seconds), and ultraviolet rays When the curable adhesive 3 was shaken off, and then the rotation of the spin table 10 was stopped and the displacement of the organic birefringent film 5 was observed, the organic birefringent film 5 was hardly moved on the transparent substrate 1.
[0024]
After the observation, the spin table 10 is rotated at 700 rpm for the first time (R1 (3) = 700 rpm, rotation time T1 (3) = 2 seconds), and the ultraviolet curable adhesive 3 is shaken off. After that, when the rotation of the spin table 10 was stopped and the displacement of the organic birefringent film 5 was observed, the organic birefringent film 5 moved about 8 mm on the transparent substrate 1. Therefore, as shown in FIGS. 1E and 2A, the adjustment jig 20 is used to slide the organic birefringent film 5 on the transparent substrate 1 to correct the position of the organic birefringent film 5. .
[0025]
After the correction, the spin table 10 is rotated again at 700 rpm for the first time (R1 (4) = 700 rpm, rotation time T1 (4) = 6 seconds) in FIG. 1 (f), and the UV curable adhesive 3 is shaken off. After that, when the rotation of the spin table 10 was stopped and the displacement of the organic birefringent film 5 was observed, the organic birefringent film 5 moved on the transparent substrate 1 by about 2 mm. After the observation, the organic birefringent film 5 was slid on the transparent substrate 1 using the adjusting jig 20 shown in FIGS. 1E and 2A to correct the position of the organic birefringent film 5.
[0026]
After the correction, the first rotation of the spin table 10 at 700 rpm (R1 (5) = 700 rpm, rotation time T1 (5) = 10 seconds) is performed again in FIG. 1F, and the ultraviolet curable adhesive 3 is shaken off. Then, when the rotation of the spin table 10 was stopped and the displacement of the organic birefringent film 5 was observed, the organic birefringent film 5 hardly moved on the transparent substrate 1.
[0027]
After the observation, the spin table 10 is again rotated at 700 rpm for the first time (R1 (6) = 700 rpm, rotation time T1 (6) = 12 seconds), and the ultraviolet curable adhesive 3 is shaken off. Thereafter, when the rotation of the spin table 10 was stopped and the displacement of the organic birefringent film 5 was observed, the organic birefringent film 5 hardly moved on the transparent substrate 1.
[0028]
After the observation, the spin table 10 is rotated at 900 rpm for the first time (R1 (7) = 900 rpm, rotation time T1 (7) = 4 seconds), and the ultraviolet curable adhesive 3 is shaken off. Thereafter, when the rotation of the spin table 10 was stopped and the displacement of the organic birefringent film 5 was observed, the organic birefringent film 5 moved about 8 mm on the transparent substrate 1.
[0029]
After the observation, the organic birefringent film 5 was slid on the transparent substrate 1 using the adjusting jig 20 shown in FIGS. 1E and 2A to correct the position of the organic birefringent film 5. After the correction, the first rotation (R1 (8) = 900 rpm, rotation time T1 (8) = 10 seconds) of the spin table is again performed at 900 rpm in FIG. 1 (f), and the ultraviolet curable adhesive 3 is shaken off. Thereafter, when the rotation of the spin table 10 was stopped and the displacement of the organic birefringent film 5 was observed, the organic birefringent film 5 moved on the transparent substrate 1 by about 2 mm. After the observation, the organic birefringent film 5 was slid on the transparent substrate 1 using the adjusting jig 20 to correct the position of the organic birefringent film 5.
[0030]
After the correction, the spin table 10 is again rotated at 900 rpm for the first time (R1 (9) = 900 rpm, rotation time T1 (9) = 22 seconds), and the UV curable adhesive 3 is shaken off. Thereafter, when the rotation of the spin table 10 was stopped and the displacement of the organic birefringent film 5 was observed, the organic birefringent film 5 hardly moved on the transparent substrate 1.
[0031]
After the observation, the spin table 10 is again rotated at 900 rpm for the first time (R1 (10) = 900 rpm, rotation time T1 (10) = 54 seconds), and the ultraviolet curable adhesive 3 is shaken off. After that, when the rotation of the spin table 10 was stopped and the displacement of the organic birefringent film 5 was observed, the organic birefringent film 5 hardly moved on the transparent substrate 1. FIG. 3 shows the transition of the rotation speed and rotation time of the first rotation in the first rotation process.
[0032]
FIG. 1 (g) shows the second rotation process, in which the spin table 10 is rotated (second rotation, the number of rotations is increased from 400 rpm to 900 rpm in 3 steps, and held at 900 rpm for 30 seconds). The adhesive 3 was shaken off, and the thickness of the adhesive layer of the ultraviolet curable adhesive 3 was made constant in the plane. Here, when the maximum rotation speed in the second rotation is R2max [rpm], R2max = 900 rpm. Further, an organic solvent 31 (in this example, using isopropyl alcohol) that dissolves the ultraviolet curable adhesive 3 before curing and does not dissolve the organic birefringent film 5 is used for the organic birefringence 5 and the transparent substrate during the second rotation process. 1 was dropped from the rinse mechanism 30 near the boundary of 1 to remove the adhesive residue around the transparent substrate 1.
[0033]
Next, as shown in FIG. 1 (h), the rotation of the spin table 10 is stopped, and ultraviolet ray UV (first ultraviolet ray) is irradiated from the organic birefringent film 5 side using a high pressure mercury lamp (not shown) to cure the ultraviolet ray. The mold adhesive 3 is cured. FIG. 1 (h) shows the curing process. Hereinafter, the transparent substrate 1 to which the organic birefringent film 5 is bonded is abbreviated as the substrate 60.
[0034]
As shown in FIG. 1 (i), the fabricated substrate 60 is removed from the spin table 10, a positive resist is applied to the organic birefringent film 5 to a thickness of 1.1 μm, and prebaking at 60 ° C. for 30 minutes is performed. Do. Thereafter, the substrate 60 is mounted on a well-known reduction projection exposure apparatus (NA = 0.45, σ = 0.6, wavelength: I), and exposure is performed using a reticle having a 1.5 μm line and space pattern having 1000 cycles. Then, development was performed using the developer NMD-3, and post-baking was performed at 100 ° C. for 30 minutes to complete a periodic resist pattern. Thereafter, aluminum (Al) is vapor-deposited on the resist pattern by sputtering, and subsequently the resist is dissolved using acetone to lift off the aluminum (Al), thereby forming an aluminum (Al) pattern obtained by inverting the resist pattern. Completed. Thereafter, the organic birefringent film 5 was etched by 4 μm in depth using an ECR etching apparatus in an etching gas atmosphere containing oxygen gas as a main component, using the aluminum (Al) pattern as a metal mask.
Thereafter, the aluminum (Al) pattern was removed using a phosphoric acid-based aluminum (Al) etching solution to complete a diffraction grating 61 that was an uneven grating having 1000 cycles.
[0035]
As shown in FIG. 1 (j), a substrate 60 on which a diffraction grating is formed is placed on a flat-processed stainless steel plate having a diameter of φ250 mm and a thickness of 50 mm, and an optically isotropic acrylic ultraviolet curable adhesive is adhered to the surface of the diffraction grating 61. 1.2 ml of isotropic adhesive 11 as an agent is dropped with a microsyringe. Then, the opposite transparent substrate 9 having a diameter of 165 mm, a thickness of 1 mm, and a material: optical glass BK7 made of Schott is mounted on the both surfaces, and further optically polished optical glass is placed on the opposite transparent substrate 9, and 100 gf / cm is placed on the opposite transparent substrate 9. 2 The isotropic adhesive 11 is spread over the entire surface to be bonded. Note that an antireflection film (not shown) is formed on the free surface (surface in contact with air) that faces the surface to be bonded of the counter transparent substrate 9 so as to minimize the reflection of incident light. In this state, the isotropic adhesive 11 is cured by irradiating ultraviolet light through the opposing transparent substrate. In FIG. 1 (j), reference numeral 1A is referred to as an intermediate complete body in which the counter transparent substrate 11 is integrated in this way.
[0036]
Next, as shown in FIG. 1 (k), several hundreds of diffraction gratings 61 included in the intermediate finished product 1A are dimmed by using a dicing saw 15 (each having one diffraction grating). To complete a plurality of polarization splitting elements 100. 1 (i) and 1 (j) show a process of forming a diffraction grating.
[0037]
The substrate 60 to which the organic birefringent film 5 is bonded by the steps of FIGS. 1A to 1H is cut using a dicing saw 15, and a cross section is observed with a 200 × metal microscope. Was measured (measurement range: 5 to 130 mm from the end of the organic birefringent film). The measurement results are shown in FIG. The thickness of the adhesive layer under these conditions was an average of 28 μm and was confirmed to be substantially uniform in the diameter direction.
[0038]
According to the manufacturing method of Example 1, the first rotation process and the correction process are repeated until the organic birefringent film 5 does not substantially move on the transparent substrate 1 by the first rotation, and then the second rotation process and the curing process. Therefore, the organic birefringent film 5 can be prevented from protruding from the transparent substrate 1.
[0039]
Further, when the first rotation process and the correction process are repeated and the rotation of the transparent substrate 1 in the first rotation process has a plurality of rotation speeds, the rotation speed of the first rotation of the Xth time is set to R1 (X) [ rpm], when the maximum rotation speed of the second rotation in the second rotation step is R2max [rpm], R2max = R1 (X) ≧ R1 (X−1) ≧... ≧ R1 (1) where X ≧ There is a relationship of two. Therefore, the number of rotations increases each time the first rotation step and the correction step are repeated, and finally the number of rotations of the first rotation coincides with the maximum value of the second rotation, that is, R2max.
[0040]
Here, even when the rotation speed of the first rotation matches the maximum value (R2max) of the second rotation, the first rotation process and the correction process are performed until the organic birefringent film 5 does not substantially move on the transparent substrate 1. Since it repeats, even if it implements 2nd rotation after performing 1st rotation, the organic birefringent film 5 hardly moves on the transparent substrate 1, and the center of the transparent substrate 1 and the center of the organic birefringent film 5 are It is kept in a state of approximately matching. For this reason, the distance between the end of the organic birefringent film 5 and the end of the transparent substrate 1 can be reduced, that is, the difference between the diameter of the organic birefringent film 5 and the diameter of the transparent substrate 1 can be reduced. As a result, the area where the polarization separation element 100 can be formed on the transparent substrate 1 can be increased, and the number of polarization separation elements 100 that can be taken from one transparent substrate 1 can be increased. Further, by taking the above steps, the thickness of the adhesive layer to which the organic birefringent film 5 is adhered can be made substantially uniform in the plane as shown in FIG.
[0041]
In this example, the organic birefringent film 5 was directly bonded to the transparent substrate 1, but an organic birefringent film having a protective film made of an organic polymer with an adhesive on one surface of the organic birefringent film 5 was used. If the protective film is peeled off after the ultraviolet light for curing is adhered to the transparent substrate 1 on the surface without the protective film, the surface of the organic birefringent film is protected during the bonding process of the transparent substrate 1 and the organic birefringent film 5. Since it is covered with a film, the probability of foreign matter or scratches on the surface of the organic birefringent film 5 can be greatly reduced. For this reason, since the pattern defect which generate | occur | produces with a foreign material or a damage | wound in a lithography process can be reduced, the manufacturing yield of the polarization splitting element 100 can be improved.
[0042]
Example 2
In FIG. 1A, a transparent substrate 1 made of shot optical glass BK7 having a diameter of 165 mm and a thickness of 1.5 mm is placed on a spin table 10 and fixed to the spin table 10 by vacuum suction, and the spin table 10 is rotated at 10 to 50 rpm. 8 to 11 g of acrylic ultraviolet curable adhesive 3 having a refractive index of 1.52 and a viscosity of 500 cp is dropped onto the center of the transparent substrate 1 using the dispenser 12. After the dropping, the spin table is rotated at 300 rpm, and as shown in FIG. 1B, the ultraviolet curable adhesive 3 is spread over the entire dropping surface of the transparent substrate 1, and then the rotation of the spin table is stopped.
[0043]
In FIG. 1C, after the rotation of the spin table 10 is stopped, the diameter 155 mm, the thickness is smaller than the diameter of the transparent substrate 1 on the spread UV curable adhesive 3 using a mounting device described later. An organic birefringent film 5 having a thickness of 80 μm is placed with its center approximately aligned with the rotation center of the spin table 10.
[0044]
After the placement, in the first rotation step shown in FIG. 1D, the spin table 10 is rotated at 400 rpm for the first time (R1 (X) = 400 rpm), and the ultraviolet curable adhesive 3 is shaken off. Then, the rotation of the spin table 10 is stopped, the positional deviation of the organic birefringent film 5 is observed, and the organic birefringent film 5 is moved on the transparent substrate 1 as shown in FIG. As shown in FIG. 2B, the position of the organic birefringent film 5 is corrected using the adjusting jig 20 and rotated again at 400 rpm until the organic birefringent film 5 does not shift in position on the transparent substrate 1. Step 1 (d) is repeated. The total of T1 (X) at 400 rpm was 10 seconds.
[0045]
In FIG. 1E, the spin table 10 is rotated at 700 rpm for the first time (R1 (X) = 700 rpm), and the ultraviolet curable adhesive 3 is shaken off. Then, the rotation of the spin table 10 is stopped, the displacement of the organic birefringent film 5 is observed, and when the organic birefringent film 5 is moved on the transparent substrate 1, the organic birefringent film 5 is used using the adjusting jig 20. The position shown in FIG. 1E is repeated until the organic birefringent film 5 is not displaced on the transparent substrate 1 by rotating again at 700 rpm. The total T1 (X) at 700 rpm was 30 seconds.
[0046]
In FIG. 1 (f), the spin table is rotated at 900 rpm for the first time (R 1 (X) = 900 rpm), and the ultraviolet curable adhesive 3 is shaken off. Then, the rotation of the spin table 10 is stopped, the positional deviation of the organic birefringent film 5 is observed, and when the organic birefringent film 5 is moved on the transparent substrate 1, the adjustment jig 20 is used to adjust the organic birefringent film 5. The position is corrected and rotated again at 900 rpm, and the process shown in FIG. 1 (f) is repeated until the organic birefringent film does not shift on the transparent substrate. The total T1 (X) at 900 rpm was 90 seconds.
[0047]
In FIG. 1 (g), the spin table is then rotated (second rotation, the number of rotations is increased from 400 rpm to 900 rpm in 3 steps and held at 900 rpm for 30 seconds), the UV curable adhesive 3 is shaken off, and the thickness of the adhesive layer Keep the thickness constant in the plane. Further, an organic solvent 31 (in this example, using isopropyl alcohol) that dissolves the pre-curing ultraviolet curable adhesive 3 and does not dissolve the organic birefringent film 5 during the second rotation is transparent to the organic birefringent film 5. Dropping from the rinse mechanism 30 to the boundary of the substrate 1 removes the adhesive residue around the transparent substrate.
[0048]
In FIG. 1 (h), the rotation of the spin table 10 is stopped, and the ultraviolet curable adhesive 3 is irradiated from the organic birefringent film 5 side with ultraviolet UV (first ultraviolet) using, for example, a high pressure mercury lamp (not shown). To cure.
[0049]
The above-described steps (a) to (h) are executed, and the substrates B to C are obtained by bonding the organic birefringent film 5 to the three transparent substrates 1. The three substrates A, B, and C have a constant total rotation time when the first rotation R1 (X) is equal. That is, it is rotated at 400 rpm for 10 seconds, 700 rpm for 30 seconds, and 900 rpm for 90 seconds, but T1 (X) itself does not match between the three substrates.
[0050]
In FIG. 1 (i), the substrates A to C are cut using a dicing saw 15, the cross section is observed with a 200 × metal microscope, and the adhesive layer thickness in the diameter direction of the substrate is measured (measurement range: 5 to 130 mm from the edge of the organic birefringent film). The average film thickness, maximum value, and minimum value in the diameter direction are shown in FIG. In the substrates A to C, the average film thickness of the adhesive layer is 25 to 26 μm, and even if the adhesive layer thickness of Example 1 is taken into account, the fluctuation of the adhesive layer between the substrates is about several μm, and the adhesive layer thickness It was confirmed that the reproducibility was good.
[0051]
According to the manufacturing method of Example 2, the first rotation process and the correction process are repeated until the organic birefringent film 5 does not substantially move on the transparent substrate 1 by the first rotation, and the first rotation has a plurality of rotation speeds. If the rotational speed of the first rotation of the Xth time is R1 (X) [rpm] and the maximum rotational speed of the second rotation in the second rotation process is R2max [rpm], then R2max = R1 ( X) ≧ R1 (X-1) ≧... ≧ R1 (1) However, when X ≧ 2 is satisfied, the total rotation time when R1 (X) is equal is made constant between the substrates. The fluctuation of the thickness of the adhesive layer can be suppressed.
[0052]
In the same process as (a) to (h) above, the organic birefringent film 5 is adhered to the three transparent substrates 1, and a diffraction grating is formed on the organic birefringent film 3 in the same manner as in Example 1. Opposite transparent substrate having a diameter of 165 mm and a thickness of 1 mm using an optically isotropic acrylic ultraviolet curable adhesive (isotropic adhesive) 11 (material: shot optical glass BK7, with an antireflection film on the back) Are then cut into 5 mm squares using a dicing saw 15 to complete a plurality of polarization separation elements 100. As a result of measuring the diffraction efficiency of any five polarized light separating elements on each substrate, the diffraction efficiency was substantially uniform. This is presumably because the film thickness variation of the adhesive layer for adhering the organic birefringent film 5 between the substrates is small.
[0053]
Example 3
A creation method of the third embodiment will be described with reference to FIG. FIG. 6A to FIG. 6K show steps of a method for manufacturing a polarization separation element.
In FIG. 6A, the transparent substrate 1 made of shot optical glass BK7 having a diameter of 165 mm and a thickness of 1.5 mm is placed on the spin table 10 and fixed to the spin table 10 by vacuum suction. Thereafter, while rotating the spin table 10 at 10 to 50 rpm, 8 to 12 g of an epoxy-based ultraviolet curable adhesive 3 having a refractive index of 1.58 and a viscosity of 600 cp was dropped onto the central portion of the transparent substrate 1 using a dispenser 12. . After the dropping, the spin table 10 is rotated at 400 rpm, and as shown in FIG. 6B, the ultraviolet curable adhesive 3 is spread on the entire surface of the transparent substrate 1, and then the rotation of the spin table 10 is stopped. FIGS. 6A and 6B show a process of applying the ultraviolet curable adhesive 3 on the transparent substrate 1.
[0054]
In FIG. 6C, after the rotation of the spin table 10 is stopped, the diameter 155 mm, the thickness, which is smaller than the diameter of the transparent substrate 1 is placed on the spread UV curable adhesive 3 using a mounting device described later. An organic birefringent film 5 having a thickness of 100 μm is placed with its center substantially aligned with the rotation center of the spin table 10. FIG. 6C shows a setting process for placing the organic birefringent film 5 on the ultraviolet curable adhesive 3.
[0055]
As shown in FIG. 6D, the spin table 10 is first rotated at 600 rpm (R1 (1) = 600 rpm, T1 (1) = 8 seconds), and the ultraviolet curable adhesive 3 is shaken off. FIG. 6D shows the first rotation process.
[0056]
6E, when the rotation of the spin table 10 is stopped and the displacement of the organic birefringent film 5 is observed, the organic birefringent film 5 is formed on the transparent substrate 1 as shown in FIG. It moved about 1 mm outward, and the center of the organic birefringent film 5 and the rotation center of the spin table 10 were not aligned. Therefore, the adjustment jig 20 is used to push the end of the organic birefringent film 5 on the outer side to the center side of the transparent substrate 1 and slide on the transparent substrate 1, as shown in FIG. The position of the organic birefringent film 5 was corrected. That is, the centers of the transparent substrate 1 and the organic birefringent film 5 are aligned, and the organic birefringent film 5 is moved to a position where the organic birefringent film 5 does not protrude from the transparent substrate 1. FIG. 6E shows a correction process.
[0057]
In FIG. 6F, the spin table is then rotated again at 600 rpm for the first time (R1 (2) = 600 rpm, rotation time T1 (2) = 2 seconds), and the adhesive is shaken off. Thereafter, when the rotation of the spin table 10 was stopped and the displacement of the organic birefringent film 5 was observed, the organic birefringent film 5 hardly moved on the transparent substrate 1.
[0058]
Thereafter, the spin table 10 is rotated at 1000 rpm for the first time (R1 (3) = 1000 rpm, rotation time T1 (3) = 5 seconds), and the adhesive is shaken off. Thereafter, when the rotation of the spin table 10 was stopped and the displacement of the organic birefringent film 5 was observed, the organic birefringent film 5 moved on the transparent substrate 1 by about 2 mm. Thereafter, using the adjusting jig 20, the organic birefringent film 5 was slid on the transparent substrate 1 to correct the position of the organic birefringent film 5.
[0059]
After the correction, the spin table is again rotated at 1000 rpm for the first time (R1 (4) = 1000 rpm, rotation time T1 (4) = 6 seconds), and the UV curable adhesive 3 is shaken off. After that, when the rotation of the spin table 10 was stopped and the displacement of the organic birefringent film 5 was observed, the organic birefringent film 5 moved on the transparent substrate 1 by about 1 mm. Thereafter, using the adjusting jig 20, the organic birefringent film 5 was slid on the transparent substrate 1 to correct the position of the organic birefringent film 5.
[0060]
After the correction, the spin table 10 is again rotated at 1000 rpm for the first time (R1 (5) = 1000 rpm, rotation time T1 (5) = 10 seconds), and the ultraviolet curable adhesive 3 is shaken off. Thereafter, when the rotation of the spin table 10 was stopped and the displacement of the organic birefringent film 5 was observed, the organic birefringent film 5 hardly moved on the transparent substrate 1.
[0061]
After the observation, the spin table 10 is again rotated at 1000 rpm for the first time (R1 (6) = 1000 rpm, rotation time T1 (6) = 9 seconds), and the UV curable adhesive 3 is shaken off. Thereafter, when the rotation of the spin table 10 was stopped and the displacement of the organic birefringent film 5 was observed, the organic birefringent film 5 hardly moved on the transparent substrate 1.
[0062]
After observation, the spin table is rotated at 1500 rpm for the first time (R1 (7) = 1500 rpm, rotation time T1 (7) = 2 seconds), and the ultraviolet curable adhesive 3 is shaken off. Thereafter, when the rotation of the spin table 10 was stopped and the displacement of the organic birefringent film 5 was observed, the organic birefringent film 5 moved about 5 mm on the transparent substrate 1. Thereafter, using the adjusting jig 20, the organic birefringent film 5 was slid on the transparent substrate 1 to correct the position of the organic birefringent film 5.
[0063]
After the correction, the spin table 10 is again rotated at 1500 rpm for the first time (R1 (8) = 1500 rpm, rotation time T1 (8) = 16 seconds), and the ultraviolet curable adhesive 3 is shaken off. Thereafter, when the rotation of the spin table 10 was stopped and the displacement of the organic birefringent film 5 was observed, the organic birefringent film 5 was moved about 3 mm on the transparent substrate 1. Thereafter, using the adjusting jig 20, the organic birefringent film 5 was slid on the transparent substrate 1 to correct the position of the organic birefringent film 5.
[0064]
After the correction, the spin table 10 is again rotated at 1500 rpm for the first time (R1 (9) = 1500 rpm, rotation time T1 (9) = 30 seconds), and the adhesive is shaken off. Thereafter, when the rotation of the spin table was stopped and the displacement of the organic birefringent film was observed, the organic birefringent film hardly moved on the transparent substrate.
[0065]
After the observation, the spin table is again rotated at 1500 rpm for the first time (R1 (10) = 1500 rpm, rotation time T1 (10) = 32 seconds), and the ultraviolet curable adhesive 3 is shaken off. Thereafter, when the rotation of the spin table 10 was stopped and the displacement of the organic birefringent film 5 was observed, the organic birefringent film 5 hardly moved on the transparent substrate 1. FIG. 7 shows the transition of the rotation speed and rotation time of the first rotation.
[0066]
In FIG. 6G, after the end of FIG. 6F, the spin table 10 is rotated (second rotation, the number of rotations is increased from 600 rpm to 1500 rpm in 3 steps. Therefore, R2max [rpm] is 1500 rpm). Then, after holding at 1500 rpm for 5 seconds, the second ultraviolet ray UV is irradiated from the organic birefringent film 5 side using a metal halide lamp (not shown) while rotating at 1500 rpm, and the ultraviolet curable adhesive 3 is gradually semi-cured. . Note that the energy of the second ultraviolet irradiation is sufficient if the ultraviolet curable adhesive 3 can be semi-cured to such an extent that the organic birefringent film 5 does not shift during the second rotation. Irradiation was performed with an energy of about 30% of the first ultraviolet UV used. FIG. 6G shows the second rotation process and the semi-curing process.
Organic birefringence is applied to the organic solvent 31 (in this example, acetone is used) that dissolves the pre-curing ultraviolet curable adhesive 3 and does not dissolve the organic birefringent film 5 while irradiating the second ultraviolet light. It was dripped from the rinse mechanism 30 to the boundary between the film 5 and the transparent substrate 1 to remove the adhesive residue around the transparent substrate.
[0067]
In FIG. 6 (h), after the process of FIG. 6 (g) is completed, the rotation of the spin table 10 is stopped, and the first ultraviolet ray UV is irradiated from the organic birefringent film side using the metal halide lamp. The adhesive 3 is completely cured. FIG. 6 (h) shows the curing process. Hereinafter, the transparent substrate 1 to which the organic birefringent film 5 is bonded is abbreviated as a substrate 62.
[0068]
As shown in FIG. 6 (i), the fabricated substrate 62 is removed from the spin table 10, a positive resist is applied to the organic birefringent film 5 to a thickness of 1.5 μm, and prebaking at 60 ° C. for 30 minutes is performed. Do. Thereafter, the substrate 60 is mounted on a reduction projection exposure apparatus (NA = 0.54, σ = 0.6, wavelength: i-line), and exposure is performed using a reticle of a 1.0 μm line-and-space pattern having 1000 cycles, Development was performed using a developer NMD-3, and post-baking was performed at 100 ° C. for 30 minutes to complete a periodic resist pattern. Thereafter, the resist pattern is exposed to 1,1,3,3-tetramethylhexadisilazane vapor at 110 ° C., and the resist surface is doped with 1,1,3,3-tetramethylhexadisilazane. Using an ECR etching apparatus, the organic birefringent film was etched to a depth of 4 μm using the resist pattern as a mask in an etching gas atmosphere containing oxygen gas as a main component. Thereafter, the resist pattern was removed by using a stripping solution, and a diffraction grating 63 to be an uneven grating having 1000 cycles was completed.
[0069]
As shown in FIG. 6 (j), a substrate 62 on which a diffraction grating 63 is formed is placed on a flattened stainless steel plate having a diameter of 200 mm and a thickness of 50 mm, and an optically isotropic epoxy UV curing type is provided on the diffraction grating 62 surface. 1.2 ml of adhesive (isotropic adhesive) 11 was dropped with a micro syringe. Then, an opposing transparent substrate 9 (material: shot optical glass BK7) having a diameter of 165 mm and a thickness of 1 mm optically polished on both sides is placed on the substrate surface coated with the isotropic adhesive 11 and further optically polished on the opposite transparent substrate. The optical glass was placed and placed on the opposite transparent substrate at 100 gf / cm 2 The isotropic adhesive 11 was spread over the entire adherend surface. Note that an antireflection film (not shown) is formed on the free surface (surface in contact with air) that faces the surface to be bonded of the counter transparent substrate 9 so as to minimize the reflection of incident light. In this state, the isotropic adhesive 11 is cured by irradiating ultraviolet light through the opposing transparent substrate. In FIG. 6 (j), reference numeral 1B indicates an intermediate completed body in which the counter transparent substrate 11 is integrated in this way.
[0070]
As shown in FIG. 6 (k), several hundred diffraction gratings 63 included in the intermediate finished product 1B are converted into 5 mm squares (each having one diffraction grating) by using a dicing saw 15. Cut out and complete a plurality of polarization splitting elements 101.
[0071]
The transparent substrate 1 to which the organic birefringent film is bonded by the steps of FIGS. 6A to 6H is cut with a dicing saw 15, and a cross section is observed with a 200 × metal microscope, and bonding in the diameter direction of the substrate is performed. FIG. 8 shows the result of measuring the layer thickness (measurement range: 5 to 130 mm from the end of the organic birefringent film). The average thickness of the adhesive layer under this condition was 32 μm, and it was confirmed that the adhesive layer was substantially uniform in the diameter direction.
[0072]
According to the manufacturing method of Example 3, the first rotation process and the correction process are repeated until the organic birefringent film 5 does not substantially move on the transparent substrate 1 by the first rotation, and then the second rotation process, the half process Since the curing step and the curing step are performed, the protrusion of the organic birefringent film 5 from the transparent substrate 1 can be prevented as in the first embodiment. Further, as shown in FIG. 6 (g), while performing the second rotation, the UV curable adhesive 3 that adheres the organic birefringent film 5 by irradiating the second UV UV is semi-cured to increase the viscosity. Therefore, the organic birefringent film 5 can be more reliably prevented from protruding from the transparent substrate 1 during the second rotation.
[0073]
When the first rotation process and the correction process are repeated and the first rotation has a plurality of rotation speeds, the rotation speed of the first rotation of the Xth time is R1 (X) [rpm], and the second rotation process When the maximum number of rotations in the second rotation is R2max [rpm],
R2max = R1 (X) .gtoreq.R1 (X-1) .gtoreq..gtoreq.R1 (1) However, since X.gtoreq.2, the number of revolutions increases each time the first rotation process and the correction process are repeated. Finally, the number of rotations of the first rotation matches the maximum value of the second rotation, that is, R2max. In this embodiment, even when the rotation speed of the first rotation coincides with the maximum value (R2max) of the second rotation, the first rotation process and the correction are performed until the organic birefringent film 5 does not move substantially on the transparent substrate 1. The process is repeated, and the second ultraviolet ray is irradiated during the second rotation so that the ultraviolet curable adhesive is semi-cured to increase the viscosity. For this reason, even if the second rotation is performed after the first rotation, the organic birefringent film 5 does not move on the transparent substrate 1, and the center of the transparent substrate 1 and the center of the organic birefringent film 5 are located. It is kept in a state of approximately matching. For this reason, the distance between the end of the organic birefringent film 5 and the end of the transparent substrate 1 can be reduced, that is, the difference between the diameter of the organic birefringent film 5 and the diameter of the transparent substrate 1 can be reduced. As a result, the area where the polarization separation element 100 can be formed on the transparent substrate 1 can be increased, and the number of polarization separation elements 100 that can be taken from one transparent substrate 1 can be increased. In addition, when the above steps are taken, the thickness of the adhesive layer to which the organic birefringent film 5 is adhered can be made substantially uniform in the plane as shown in FIG.
[0074]
Example 4
A creation method according to the fourth embodiment of the present invention will be described.
6A. The transparent substrate 1 made of shot optical glass BK7 having a diameter of 165 mm and a thickness of 1.5 mm was placed on the spin table 10 and fixed to the spin table 10 by vacuum suction. Thereafter, while rotating the spin table 10 at 10 to 50 rpm, 8 to 12 g of an epoxy ultraviolet curable adhesive 3 having a refractive index of 1.58 and a viscosity of 600 cp was dropped onto the central portion of the transparent substrate 1 using a dispenser 12. After the dropping, the spin table 10 is rotated at 400 rpm, and as shown in FIG. 6B, the ultraviolet curable adhesive 3 is spread on the entire surface of the transparent substrate 1, and then the rotation of the spin table 10 is stopped.
[0075]
In FIG. 6C, a diameter of 155 mm and a thickness of 90 μm are formed on the ultraviolet curable adhesive 3 by using a mounting device described later while substantially aligning the center of the organic birefringent film 5 with the rotation center of the spin table 10. The organic birefringent film 5 is placed.
[0076]
In FIG. 6D, after placing, the spin table 10 is rotated at 600 rpm for the first rotation (R1 (X) = 600 rpm), and the ultraviolet curable adhesive 3 is shaken off. Then, the rotation of the spin table 10 is stopped, the positional deviation of the organic birefringent film 5 is observed, and when the organic birefringent film 5 is moved on the transparent substrate 1, the adjustment jig 20 is used to adjust the organic birefringent film 5. The position is corrected and rotated again at 600 rpm, and the process shown in FIG. 6D is repeated until the organic birefringent film 5 does not cause a positional shift on the transparent substrate 1. The total T1 (X) at 600 rpm was 10 seconds.
[0077]
In FIG. 6E, after the step of FIG. 6D, the spin table 10 is first rotated at 1000 rpm (R1 (X) = 1000 rpm), and the ultraviolet curable adhesive 3 is shaken off. Then, the rotation of the spin table 10 is stopped, the positional deviation of the organic birefringent film 5 is observed, and when the organic birefringent film 5 is moved on the transparent substrate 1, the adjustment jig 20 is used to adjust the organic birefringent film 5. The position is corrected and rotated again at 1000 rpm, and the process of FIG. 6E is repeated until the organic birefringent film 5 does not cause a positional shift on the transparent substrate 1. The total sum of T1 (X) at 1000 rpm was 30 seconds.
[0078]
In FIG. 6F, the spin table 10 is further rotated at 1500 rpm for the first time (R1 (X) = 1500 rpm), and the ultraviolet curable adhesive 3 is shaken off. Then, the rotation of the spin table 10 is stopped, the positional deviation of the organic birefringent film 5 is observed, and when the organic birefringent film 5 is moved on the transparent substrate 1, the position of the organic birefringent film is adjusted using the adjusting jig 20. Correction is performed, the rotation is again performed at 1500 rpm, and the process of FIG. 6F is repeated until the organic birefringent film 5 does not cause misalignment on the transparent substrate 1. The total T1 (X) at 1500 rpm was 80 seconds.
[0079]
In FIG. 6G, after the step of FIG. 6F, the spin table 10 is rotated (the second rotation, the number of rotations is increased from 1500 rpm to 1500 rpm in 3 steps. Therefore, R2max [rpm] is 1500 rpm). Then, after holding at 1500 rpm for 5 seconds, the second ultraviolet ray UV is irradiated from the organic birefringent film 5 side using a metal halide lamp (not shown) while rotating at 1500 rpm, and the ultraviolet curable adhesive 3 is gradually semi-cured. It was. Note that the energy of the second ultraviolet irradiation was the same as in Example 3 with the energy of about 30% of the first ultraviolet used in Example 1. Further, while the second ultraviolet ray is irradiated, an organic solvent 31 (in this example, acetone) that dissolves the ultraviolet curable adhesive 3 before complete curing and does not dissolve the organic birefringent film 5 is used. It was dripped from the rinsing mechanism 30 to the boundary between the refractive film 5 and the transparent substrate 1 to remove the adhesive residue around the transparent substrate.
[0080]
In FIG. 6 (h), after the semi-curing process, the rotation of the spin table 10 is stopped, and the first ultraviolet ray is irradiated from the organic birefringent film 5 side using a metal halide lamp, and the ultraviolet curable adhesive 3 is completely removed. Cured.
[0081]
6A to 6H were performed to produce substrates D to F in which the organic birefringent film 5 was bonded to the three transparent substrates 1. The three substrates D to F have a constant total rotation time when the first rotation R1 (X) is equal. That is, it is rotated at 600 rpm for 10 seconds, 1000 rpm for 30 seconds, and 1500 rpm for 80 seconds, but T1 (X) itself does not match between the three substrates.
[0082]
In FIG. 6 (i), the substrates D to F are cut using the dicing saw 10 after curing, the cross section is observed with a 200-fold metal microscope, and the thickness of the adhesive layer in the diameter direction of the substrate is measured (measurement). Range: 5 to 130 mm from the edge of the organic birefringent film). The average film thickness, maximum value, and minimum value in the diameter direction are shown in FIG. In the substrates D to F, the average thickness of the adhesive layer was 32 to 33 μm, and the variation of the ultraviolet curable adhesive 3 between the substrates was about several μm as in Example 2.
[0083]
According to the manufacturing method of Example 4, the step of adhering the organic birefringent film 5 having a different refractive index with respect to the vibration surface having different incident light on the transparent substrate 1 includes the above-described steps. When the first rotation process and the correction process are repeated until the birefringent film 5 does not substantially move on the transparent substrate 1, and the first rotation has a plurality of rotation speeds, the rotation speed of the first rotation of the Xth time R1 (X) [rpm], and the maximum rotation speed in the second rotation in the second rotation step is R2max [rpm],
R2max = R1 (X) .gtoreq.R1 (X-1) .gtoreq..gtoreq.R1 (1) However, when X.gtoreq.2, the total rotation time when R1 (X) is equal is constant. As a result, fluctuations in the thickness of the adhesive layer among a plurality of substrates can be suppressed. 6A to 6H, the organic birefringent film 5 is adhered to the three transparent substrates, and the diffraction grating 63 is formed on the organic birefringent film 5 in the same manner as in the third embodiment. An optically isotropic epoxy-based UV curable adhesive (isotropic adhesive) 11 is used to form an opposing transparent substrate having a diameter of 165 mm and a thickness of 1 mm (material: shot optical glass BK7, antireflection on the back surface) The film was cut into 5 mm square using a dicing saw 15 shown in FIG. 6 (k), and a plurality of polarization separation elements 101 were completed. As a result of measuring the diffraction efficiency for any five polarization separation elements 101 on each substrate, the diffraction efficiency was substantially uniform. This is presumably because the thickness of the adhesive layer for adhering the organic birefringent film between the substrates is uniform.
[0084]
In Examples 1 to 4, the method of applying the ultraviolet curable adhesive 3 to the transparent substrate 1 is performed by dropping the ultraviolet curable adhesive 3 from the dispenser 12 while rotating the transparent substrate 1, and then increasing the number of rotations to make it uniform. The spin table 10 is stopped and the UV curable adhesive 3 is dropped from the dispenser 12, and then the transparent substrate 1, that is, the spin table 10 is rotated to cure the UV. The mold adhesive 3 may be spread over the entire transparent substrate. Further, the present invention is not necessarily limited to the above coating method, and any method can be used as long as a uniform coating thickness can be obtained. For example, a spray method or a roll coating method may be used.
[0085]
Example 5
FIG. 10 shows a configuration example of the optical pickup device of the present invention. The CD-RW optical pickup apparatus 200 shown in FIG. 10 reads information from a CD, writes information to the CD-RW, and reads information. In the optical pickup device, light having a wavelength of 780 nm emitted from the laser diode 81 passes through the polarization separation element 100, the collimator lens 85, the λ / 4 wavelength plate 86, and the objective lens 87 of the first embodiment, and then irradiates the CD-RW 90. To do. The irradiated light is reflected by the recording pits of the CD-RW 90, and the reflected light is linearly polarized by the λ / 4 wavelength plate 86, and then diffracted by the polarization separation element 83 and guided to the photodiode 89 for focusing. Detection, track detection, and signal detection are performed.
[0086]
When the signal was recorded on the CD-RW 90 using the optical pickup device of this example and then the signal was reproduced with the same optical pickup device, a conventional beam splitter combined with a prism and a λ / 4 wavelength plate was combined. A reproduction signal output equivalent to that of an optical pickup device for CD-RW could be obtained, and it was confirmed that the optical pickup device of this example had recording / reproduction characteristics equivalent to those of a conventional optical pickup device. Further, in the pickup device of the present embodiment, the polarization separation element 100 is smaller than the beam splitter to which the prism is bonded, and the size can be reduced as compared with the conventional optical pickup device.
[0087]
Example 6
FIG. 11 shows another configuration example of the optical pickup device of the present invention. An optical pickup device 300 for DVD shown in FIG. 11 reads information from a CD and reads information from a DVD-ROM 91. In the DVD optical pickup apparatus, the light having a wavelength of 680 nm emitted from the laser diode 82 passes through the polarization separation element 101, the collimator lens 85, the λ / 4 wavelength plate 86, and the objective lens 87 of Example 3, and then the DVD- The ROM 91 is irradiated. Reflected light from the recording pits of the DVD-ROM 91 is linearly polarized by the λ / 4 wavelength plate 86 and then diffracted by the polarization separation element 101 and guided to the photodiode 89 for focus detection, track detection, and signal detection. Is called.
[0088]
When the information signal was reproduced from the DVD-ROM 91 using the optical pickup device of this embodiment, a signal equivalent to that of a conventional DVD optical pickup device combining a beam splitter with a prism attached and a λ / 4 wavelength plate. An output can be obtained, and it has been confirmed that the optical pickup device of this example has reproduction characteristics equivalent to those of the conventional optical pickup device. Further, in the optical pickup device of the present embodiment, the polarization separating element 101 is smaller than the beam splitter to which the prism is bonded, so that the size is smaller than the conventional optical pickup device.
[0089]
Example 7
FIG. 12 shows an example of the organic birefringent film bonding apparatus of the present invention. The bonding apparatus 400 applies the ultraviolet curable adhesive 3 to the spin table 10 that holds the transparent substrate 1, the stepping motor 71 that rotates the spin table 10, the rotation mechanism 70 that has a drive transmission mechanism (not shown), and the transparent substrate 1. The two ends of the organic birefringent film 5 are adsorbed and held by the dispenser 12 and the two adsorbing arms 50 and 50 as an application mechanism, and the organic birefringent film 5 is placed on the ultraviolet curable adhesive 3 applied on the transparent substrate 1. The mounting mechanism 55 to be mounted, the position adjusting mechanism 40 for sliding the organic birefringent film 5 on the transparent substrate 1 to correct the position, the ultraviolet curable adhesive before curing is dissolved, and the organic birefringent film is not dissolved A rinsing mechanism 30 for dropping an organic solvent (see FIGS. 1 and 6) onto the transparent substrate 1, an ultraviolet ray comprising a high-pressure mercury lamp, a metal halide lamp, or the like that irradiates the transparent substrate 1 with ultraviolet rays. And a morphism mechanism 60 and the like. The position adjusting mechanism 44 has an adjustment jig 20 attached to the tip of a biaxial arm 41 that can move in the X and Y directions. The refractive film 5 is pushed and slides on the transparent substrate 1.
[0090]
The procedure for bonding the organic birefringent film 5 using the bonding apparatus of this embodiment will be described next. A transparent substrate 1 made of shot optical glass BK7 having a diameter of 165 mm and a thickness of 1.5 mm is placed on the spin table 10 and fixed to the spin table 10 by vacuum suction. Thereafter, the dispenser 12 is moved by the robot arm 31 to the central portion of the transparent substrate 1, and the acrylic resin having a refractive index of 1.52 and a viscosity of 500 cp is used by using the dispenser 12 at the central portion of the transparent substrate 1 while rotating the spin table 10 at 20 rpm. 10 g of the system ultraviolet curable adhesive 3 is dropped.
[0091]
Thereafter, the dispenser 12 is returned to the original position shown in the figure, the spin table 10 is rotated at 300 rpm, the ultraviolet curable adhesive 3 is spread on the entire surface of the transparent substrate 1, and then the rotation of the spin table 10 is stopped. Thereafter, both ends of the organic birefringent film 5 having a diameter of 155 mm and a thickness of 80 μm are held by vacuum suction on the two suction arms 50 and 50 of the mounting mechanism 55, and the mounting mechanism 55 is moved onto the transparent substrate 1. While gradually aligning the center of the organic birefringent film 5 with the center of rotation of the spin table 10, the vacuum adsorption of the two adsorption arms 50, 50 is gradually released, and the ultraviolet curable adhesive 3 spread over the entire surface of the transparent substrate. An organic birefringent film 5 is placed thereon.
[0092]
Thereafter, the mounting device 55 is returned to the original position shown in the drawing, the spin table 10 is rotated at 400 rpm (first rotation), and the ultraviolet curable adhesive 3 is shaken off. Thereafter, the rotation of the spin table 10 is stopped, the biaxial arm 41 is moved, the adjustment jig 20 is brought into contact with the side surface of the organic birefringent film 5, and the biaxial arm is moved to X, X according to the positional deviation of the organic birefringent film 5. The organic birefringent film 5 is pushed by the adjusting jig 20 and slid on the transparent substrate 1 to correct the position of the organic birefringent film 5.
[0093]
After the position adjustment is completed, the biaxial arm 41 is returned to the original position, the transparent substrate 1 is rotated again at 400 rpm (first rotation), and the organic birefringence film 5 does not move on the transparent substrate 1 by the first rotation. Repeat the above operation until Thereafter, the spin table 10 is rotated at 700 rpm (first rotation), and the ultraviolet curable adhesive 3 is shaken off.
[0094]
Thereafter, the rotation of the spin table 10 is stopped, the biaxial arm 41 is moved, the adjustment jig 20 is brought into contact with the side surface of the organic birefringent film 5, and the biaxial arm 41 is moved to X according to the misalignment of the organic birefringent film 5. The organic birefringent film 5 is pushed with the adjusting jig 20 and is slid on the transparent substrate 1 to correct the position of the organic birefringent film 5.
[0095]
After the position adjustment is completed, the biaxial arm 41 is returned to the original position shown in the figure, the transparent substrate 1 is rotated again at 700 rpm (first rotation), and the organic birefringent film 5 is placed on the transparent substrate 1 by the first rotation. Repeat the above operation until it stops moving. Thereafter, the spin table is rotated at 900 rpm (first rotation), and the ultraviolet curable adhesive 3 is shaken off.
[0096]
Thereafter, the rotation of the spin table 10 is stopped, the biaxial arm 41 is moved, the adjustment jig 20 is brought into contact with the side surface of the organic birefringent film 5, and the biaxial arm 41 is moved to X according to the misalignment of the organic birefringent film 5. The organic birefringent film 5 is pushed by the adjusting jig 20 in the Y direction, and the organic birefringent film 5 is slid on the transparent substrate 1 to correct its position. After the position adjustment is completed, the biaxial arm 41 is returned to the original position shown in the figure, the transparent substrate 1 is rotated again at 900 rpm (first rotation), and the organic birefringent film 5 is transparent substrate 1 by the first rotation. Repeat the above operation until it stops moving.
[0097]
Thereafter, the second rotation (increase the number of rotations from 400 rpm to 900 rpm in 3 steps) is performed, and the ultraviolet curable adhesive 3 is shaken off to make the thickness of the adhesive layer constant in the plane. Further, during the second rotation, the rinsing mechanism 30 is moved onto the organic birefringent film to dissolve the ultraviolet curable adhesive 3 before curing and not the organic birefringent film 5 (isopropyl in this example). (Using alcohol) is dropped to remove the UV curable adhesive remaining on the periphery of the substrate.
[0098]
Thereafter, the rotation of the spin table 10 is stopped, and the rinse mechanism 30 is returned to the original position. Then, the ultraviolet irradiation mechanism 60 is moved onto the transparent substrate 1, and the ultraviolet curable adhesive 3 is cured by irradiating the first ultraviolet from the organic birefringent film 5 side, that is, in this example, the direction perpendicular to the paper surface. After completion of the ultraviolet irradiation, the ultraviolet irradiation mechanism 60 is returned to the original position shown in the figure, the vacuum adsorption of the spin table 10 is released, and the transparent substrate 1 to which the organic birefringent film 5 is bonded is taken out.
[0099]
When the bonding apparatus having the configuration as shown in FIG. 12 is used, the method for manufacturing the polarization separation element 100 of Examples 1 and 2 can be realized, and thus the protrusion of the organic birefringent film 5 from the transparent substrate 1 can be prevented. Moreover, since the organic solvent which does not melt | dissolve the ultraviolet curable adhesive 3 before hardening and the organic birefringent film | membrane 5 is dripped from the rinse mechanism 30, the ultraviolet curable adhesive 3 which remained in the board | substrate peripheral part can be removed. .
[0100]
In addition, when the first rotation R1 (X) has a plurality of rotation speeds, the method of manufacturing the polarization separation element 101 of Example 3 is made constant by making the total sum of the rotation times when R1 (X) are equal. Therefore, variation (variation) in the thickness of the adhesive layer between the substrates can be suppressed.
[0101]
In this example, after the second rotation is completed, the first ultraviolet ray is irradiated to cure the ultraviolet curable adhesive. However, during the second rotation, the ultraviolet irradiation mechanism 60 is moved onto the transparent substrate 1 and the organic birefringence is moved. The ultraviolet curable adhesive 3 is semi-cured by irradiating the second ultraviolet ray from the film 5 side, and then the rotation of the spin table 10 is stopped, the rinse mechanism 30 is returned to the original position, and the When the ultraviolet curable adhesive 3 is cured by irradiating the first ultraviolet ray from the birefringent film 5 side, the method for producing the polarization separation element of Examples 3 and 4 can be realized. The protrusion and positional deviation of the film 5 can be more reliably suppressed.
[0102]
Further, when the first rotation R1 (X) has a plurality of rotation speeds, the method of manufacturing the polarization separation element of Example 4 can be realized by making the total sum of the rotation times when R1 (X) are equal. Therefore, variation (variation) in the thickness of the adhesive layer between the substrates can be suppressed.
[0103]
In this example, since there is one ultraviolet irradiation mechanism 60, the first and second ultraviolet irradiations irradiate the first ultraviolet ray and the second ultraviolet ray by changing the irradiation time, the irradiation distance, etc., but the light intensity is different. Two ultraviolet irradiation mechanisms may be provided to irradiate the first ultraviolet ray and the second ultraviolet ray, respectively.
[0104]
【The invention's effect】
According to the present invention, the first rotation process and the correction process are repeated until the organic birefringence film does not substantially move on the transparent substrate by the first rotation, and then the second rotation process and the curing process are performed, thereby transparent The protrusion of the organic birefringent film from the substrate is suppressed, and in the lithography / dry etching process for forming the diffraction grating, the side surface of the substrate can be clamped by the transfer in the apparatus or between the processes, resulting in the occurrence of a transfer failure. Can be suppressed.
[0105]
According to the present invention, the first rotation process and the correction process are repeated until the organic birefringent film does not substantially move on the transparent substrate by the first rotation, and then the second rotation process, the semi-curing process, and the curing process are performed. As a result, the UV curable adhesive is semi-cured during the second rotation to increase the viscosity, so that the protrusion of the organic birefringent film from the transparent substrate is further suppressed, and the lithography / In a dry etching process or the like, the side surface of the substrate can be clamped by conveyance within the apparatus or between processes, and the occurrence of conveyance defects can be further suppressed.
[0106]
According to the present invention, when the rotation speed of the first rotation of the Xth time is R1 (X) [rpm] and the maximum rotation speed in the second rotation in the second rotation process is R2max [rpm], R2max = R1 (X) ≧ R1 (X−1) ≧ ・ ・ ・ ≧ R1 (1) However, since X ≧ 2 is established, the number of rotations increases each time the first rotation step and the correction step are repeated. The rotation speed of the first rotation coincides with the maximum value of the second rotation, that is, R2max. For this reason, even when the rotation speed of the first rotation matches the maximum value (R2max) of the second rotation, the first rotation process and the correction process are repeated until the organic birefringent film does not substantially move on the transparent substrate. Thus, since the second rotation is performed after the first rotation, the organic birefringent film is difficult to move on the transparent substrate, and the distance between the end of the organic birefringent film and the end of the transparent substrate is reduced. it can. For this reason, the area on which the polarization separation element can be formed on the substrate is increased, the number of polarization separation elements that can be taken from one substrate can be increased, the production efficiency is improved, and the thickness of the adhesive layer for adhering the organic birefringent film The thickness can be made substantially uniform in the plane. In addition, in the case of having a semi-curing process, the organic birefringent film becomes difficult to move on the transparent substrate by increasing the viscosity of the ultraviolet curable adhesive. The area where the polarization separation element can be formed on the substrate can be further increased, the number of polarization separation elements that can be taken from a single substrate can be increased, and the production efficiency can be improved.
[0107]
According to the present invention, when the first rotation process and the correction process are repeated and R1 (X) has a plurality of rotation speeds, the total rotation time when R1 (X) is equal is calculated. Between transparent substrates Since it is constant, fluctuations in the thickness of the adhesive layer that adheres the organic birefringent film between the substrates can be suppressed.
[0108]
According to the present invention, the organic birefringent film can be prevented from protruding or misaligned from the transparent substrate in the organic birefringent film adhering step. Therefore, in the lithography / dry etching process, the substrate side surface can be transported in the apparatus or between processes. Even if it clamps, since a conveyance defect does not generate | occur | produce easily, a yield improves. In particular, when R1 (X) has a plurality of rotation speeds, when the total rotation time when R1 (X) is equal is made constant, the thickness variation of the adhesive layer between the substrates is small. The diffraction efficiency between the separation elements can be made uniform.
[0109]
According to the present invention, a polarization separating element having a diffraction grating provided on an organic birefringent film can be used in an optical pickup device, so that it can be made smaller than a conventional beam splitter to which a prism is bonded. Can be achieved.
[0110]
According to the present invention, since the method for producing a polarization separation element having the above-described effect can be realized, it is possible to suppress the protrusion or misalignment of the organic birefringent film from the transparent substrate in the organic birefringent film adhesion step.
[Brief description of the drawings]
FIG. 1 is a process diagram showing an example of a method for manufacturing a polarization separation element.
FIG. 2 is a perspective view showing a misaligned state and a corrected state of an organic birefringent film.
FIG. 3 is a graph showing changes in the rotation speed and rotation time of the first rotation in the first embodiment.
4 is a diagram showing a state of displacement of the adhesive layer thickness in Example 1. FIG.
5 is a view showing a change state of the film thickness of an adhesive layer in Example 2. FIG.
FIG. 6 is a process diagram showing another example of a method for manufacturing a polarization separation element.
7 is a graph showing changes in the number of first rotations and the rotation time in Example 3. FIG.
8 is a diagram showing a state of displacement of the adhesive layer thickness in Example 3. FIG.
9 is a diagram showing a state of displacement of the adhesive layer thickness in Example 4. FIG.
FIG. 10 is a diagram illustrating an example of an optical pickup device.
FIG. 11 is a diagram illustrating another example of the optical pickup device.
FIG. 12 is a view showing an example of an organic birefringent film bonding apparatus.
FIG. 13 is a process diagram showing a conventional method of manufacturing a polarization separation element.
FIG. 14 is a process diagram showing a method for producing a bonded optical disc.
[Explanation of symbols]
1 Transparent substrate
3 UV curable adhesive
5 Organic birefringent film
10 Spin table
12 Coating mechanism
40 Position adjustment mechanism
55 Placement mechanism
60 UV irradiation mechanism
61, 63 Diffraction grating with irregularities
70 Rotating mechanism
100, 101 Polarization separation element
200,300 Optical pickup device
400 Bonding device

Claims (7)

透明基板上に、入射光の異なる振動面に対して屈折率が異なる有機複屈折膜を接着する接着工程と、上記有機複屈折膜上に周期的なマスクパターンを形成し、このマスクパターンを用いて有機複屈折膜をエッチングして周期的な凹凸による回折格子を形成する工程とを有する偏光分離素子の作製方法において、
前記接着工程が、透明基板上に紫外線硬化型接着剤を塗布する工程、紫外線硬化型接着剤上に有機複屈折膜を載せるセット工程、有機複屈折膜が載せられた透明基板を第１の回転で回転する第１回転工程、第１の回転で回転する透明基板の回転を止めて有機複屈折膜を透明基板上で滑動して位置修正を行う修正工程、透明基板を第２の回転で回転する第２回転工程、第２の回転で回転する透明基板の回転を止め、紫外線を照射して紫外線硬化型接着剤を硬化する硬化工程を有し、
第１の回転によって有機複屈折膜が透明基板上で略動かなくなるまで第１回転工程と修正工程とを繰り返し、その後、第２回転工程と硬化工程とを行うことを特徴とする偏光分離素子の作製方法。Adhering step of adhering organic birefringent film having different refractive index to vibration surface with different incident light on transparent substrate, and forming periodic mask pattern on the organic birefringent film, and using this mask pattern A method for producing a polarization separation element, comprising: etching the organic birefringent film to form a diffraction grating with periodic unevenness;
The bonding step includes a step of applying an ultraviolet curable adhesive on a transparent substrate, a setting step of placing an organic birefringent film on the ultraviolet curable adhesive, and a first rotation of the transparent substrate on which the organic birefringent film is placed. The first rotation process that rotates at the first rotation, the correction process that stops the rotation of the transparent substrate that rotates at the first rotation and corrects the position by sliding the organic birefringent film on the transparent substrate, and the second rotation of the transparent substrate The second rotation step, the rotation of the transparent substrate rotating in the second rotation is stopped, and the curing step of curing the ultraviolet curable adhesive by irradiating ultraviolet rays,
A polarization separation element characterized by repeating the first rotation step and the correction step until the organic birefringent film substantially does not move on the transparent substrate by the first rotation, and then performing the second rotation step and the curing step. Manufacturing method. 請求項１項に記載の偏光分離素子の作製方法において、
第１回転工程と修正工程を繰り返し、かつ第１回転工程での透明基板の回転が複数の回転数を有する場合、Ｘ回目の第１の回転の回転数をＲ１（Ｘ）［ｒｐｍ］、第２回転工程での第２の回転の最大の回転数をＲ２ｍａｘ［ｒｐｍ］すると、Ｒ２ｍａｘ＝Ｒ１（Ｘ）≧Ｒ１（Ｘ−１）≧・・・≧Ｒ１（１） 但しＸ≧２の関係にあることを特徴とする偏光分離素子の作製方法。In the manufacturing method of the polarization splitting device according to claim 1,
When the first rotation process and the correction process are repeated and the rotation of the transparent substrate in the first rotation process has a plurality of rotation speeds, the rotation speed of the first rotation of the Xth time is R1 (X) [rpm], R2max = R1 (X) ≧ R1 (X−1) ≧...> R1 (1) where X ≧ 2 when the maximum number of rotations of the second rotation in the two-rotation process is R2max [rpm]. There is provided a method for manufacturing a polarization separation element. 請求項２項に記載の偏光分離素子の作製方法において、
第１回転工程と修正工程を繰り返し、かつＲ１（Ｘ）が複数の回転数を有する場合、Ｒ１（Ｘ）が等しい時の回転時間の総和が透明基板間で一定であることを特徴とする偏光分離素子の作製方法。In the manufacturing method of the polarization splitting device according to claim 2,
Polarization characterized in that when the first rotation step and the correction step are repeated and R1 (X) has a plurality of rotation speeds, the total rotation time when R1 (X) is equal is constant between the transparent substrates. A method for manufacturing a separation element. 透明基板上に入射光の異なる振動面に対して屈折率が異なる有機複屈折膜を接着する工程と、前記の有機複屈折膜上に周期的なマスクパターンを形成し、前記のマスクパターンを用いて有機複屈折膜をエッチングして周期的な凹凸状の回折格子を形成する工程からなる偏光分離素子の作製方法において、
前記接着工程が、透明基板上に紫外線硬化型接着剤を塗布する工程、紫外線硬化型接着剤上に有機複屈折膜を載せるセット工程、有機複屈折膜が載せられた透明基板を第１の回転で回転する第１回転工程、第１の回転で回転する透明基板の回転を止めて有機複屈折膜を透明基板上で滑動して位置修正を行う修正工程、透明基板を第２の回転で回転する第２回転工程、第２回転工程中に紫外線を照射して、紫外線硬化型接着剤を半硬化する半硬化工程、第２の回転で回転する透明基板の回転を止め、紫外線を照射して紫外線硬化型接着剤を硬化する硬化工程を有し、
第１の回転によって有機複屈折膜が透明基板上で略動かなくなるまで第１回転工程と修正工程とを繰り返し、その後、第２回転工程、半硬化工程、硬化工程を行うことを特徴とする偏光分離素子の作製方法。A step of adhering an organic birefringent film having a different refractive index to a vibration surface having different incident light on a transparent substrate, a periodic mask pattern is formed on the organic birefringent film, and the mask pattern is used. In the method of manufacturing a polarization separation element comprising the step of etching the organic birefringent film to form a periodic uneven diffraction grating,
The bonding step includes a step of applying an ultraviolet curable adhesive on a transparent substrate, a setting step of placing an organic birefringent film on the ultraviolet curable adhesive, and a first rotation of the transparent substrate on which the organic birefringent film is placed. The first rotation process that rotates at the first rotation, the correction process that stops the rotation of the transparent substrate that rotates at the first rotation and corrects the position by sliding the organic birefringent film on the transparent substrate, and the second rotation of the transparent substrate The second rotation step, the semi-curing step of semi-curing the ultraviolet curable adhesive by irradiating ultraviolet rays during the second rotating step, stopping the rotation of the transparent substrate rotating in the second rotation, and irradiating the ultraviolet rays Having a curing step to cure the UV curable adhesive;
Polarized light characterized by repeating the first rotation process and the correction process until the organic birefringent film does not move substantially on the transparent substrate by the first rotation, and then performing the second rotation process, the semi-curing process, and the curing process. A method for manufacturing a separation element. 請求項４項に記載の偏光分離素子の作製方法において、
第１回転工程と修正工程を繰り返し、かつ第１回転工程での透明基板の回転が複数の回転数を有する場合、Ｘ回目の第１の回転の回転数をＲ１（Ｘ）［ｒｐｍ］、第２回転工程での第２の回転の最大の回転数をＲ２ｍａｘ［ｒｐｍ］すると、Ｒ２ｍａｘ＝Ｒ１（Ｘ）≧Ｒ１（Ｘ−１）≧・・・≧Ｒ１（１） 但しＸ≧２の関係にあることを特徴とする偏光分離素子の作製方法。In the manufacturing method of the polarization separation element according to claim 4,
When the first rotation process and the correction process are repeated and the rotation of the transparent substrate in the first rotation process has a plurality of rotation speeds, the rotation speed of the first rotation of the Xth time is R1 (X) [rpm], R2max = R1 (X) ≧ R1 (X−1) ≧...> R1 (1) where X ≧ 2 when the maximum number of rotations of the second rotation in the two-rotation process is R2max [rpm]. There is provided a method for manufacturing a polarization separation element. 請求項５項に記載の偏光分離素子の作製方法において、
第１回転工程と修正工程を繰り返し、かつＲ１（Ｘ）が複数の回転数を有する場合、Ｒ１（Ｘ）が等しい時の回転時間の総和が透明基板間で一定であることを特徴とする偏光分離素子の作製方法。In the manufacturing method of the polarization splitting device according to claim 5,
Polarization characterized in that when the first rotation step and the correction step are repeated and R1 (X) has a plurality of rotation speeds, the total rotation time when R1 (X) is equal is constant between the transparent substrates. A method for manufacturing a separation element. 透明基板を保持するスピンテーブルと、
このスピンテーブルを回転させる回転機構と、
上記スピンテーブルに保持された透明基板に、紫外線硬化型接着剤を塗布する塗布機構と、
上記透明基板上に塗布された紫外線硬化型接着剤の上に有機複屈折膜を載置する載置機構と、
上記透明基板上に載置された有機複屈折膜を当該透明基板上で滑動して位置を修正する位置調整機構と、
上記有機複屈折膜を介して上記紫外線硬化型接着剤に紫外線を照射する紫外線照射機構とを有する有機複屈折膜の接着装置。 A spin table holding a transparent substrate;
A rotation mechanism for rotating the spin table;
An application mechanism for applying an ultraviolet curable adhesive to the transparent substrate held by the spin table;
A mounting mechanism for mounting an organic birefringent film on the ultraviolet curable adhesive applied on the transparent substrate;
A position adjusting mechanism for correcting the position by sliding the organic birefringent film placed on the transparent substrate on the transparent substrate;
An organic birefringent film bonding apparatus having an ultraviolet irradiation mechanism for irradiating the ultraviolet curable adhesive with ultraviolet rays through the organic birefringent film .
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