JP3707269B2 - Manufacturing method of liquid crystal device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of defects by the adhesion of alignment stock to sealing portions, packaging portions, etc., to improve productivity and to reduce a production cost. SOLUTION: An alignment layer 12 on a panel substrate 10 is subjected to an alignment treatment by diagonally irradiating the alignment layer 12 with ions (a) and thereafter, the unnecessary portions of the alignment layer 12 are removed by the irradiation with the ions in the state of installing a mask 13. The ion acceleration is preferably 1000 V to 1500 V when the ion current density is 15 μA/cm2 to 25 μA/cm2 and the ion irradiation time is >=20 seconds.

Description

【００２８】
【化２】

【００２９】
などの主鎖を持つものが、高い電圧保持率、均一な液晶配向及び高いプレチルト角を実現するために特に適している。
【００３０】
また、ポリアミック酸タイプのポリイミド素材としては、
【００３１】
【化３】

【００３２】
の主鎖部の構造を備えたものがある。
【００３３】
上記のようにして表面上に配向膜１２を形成したパネル基板１０をイオン照射装置のチャンバー内に導入した。そして、チャンバー内部を真空にして、イオン源２１からＡｒイオンを放出させ、加速電極２２によって加速して照射した。
【００３４】
このイオン照射は配向膜１２に配向処理を施すためのものである。このときの真空度は５×１０^−３ｔｏｒｒであり、イオン照射角度はθ＝４５°であり、加速電圧１００Ｖ、電流密度２０μＡ／ｃｍ^２ の条件でＡｒイオンを照射した。また、この照射条件で、パネル基板１０を図示矢印の方向（すなわち、パネル基板１０のパネル面に平行な（含まれる）方向であって、イオン源２１がパネル面に対して傾斜している方位に向かう方向）に１ｃｍ／秒の速度で移動（走査）させながら配向処理を実施した。もちろん、パネル基板１０の代わりにイオン源２１を走査してもよい。
【００３５】
配向処理におけるイオン照射の条件は、図２に示すイオン加速電圧と液晶分子のプレチルト角及び配向秩序度との関係（イオンの照射角度を４５°とした場合のデータである。）、図３に示す照射角度とプレチルト角及び配向秩序度との関係（イオン加速電圧を１００Ｖとした場合のデータである。）、図４に示す真空度と配向秩序度との関係（照射角度を４５°、イオン加速電圧を１００Ｖとし、イオン照射口から配向膜１２までの距離をＬとしたときのデータである。）などから最適化されることが好ましい。
【００３６】
ここで、プレチルト角は配向膜１２に接する液晶分子の角度であり、「液晶 応用」（岡野光治／小林駿介 共編）第６３頁に記載されている磁界電位法を用いて１８０°配向処理方向が異なるアンチパラレル液晶セルで測定を行ったものである。配向秩序度は、同書第２８頁に記載されているＧＨ（ゲストホスト）液晶を用いて測定を行ったものであり、少なくとも１ｃｍ^２以上の面積範囲において平均をとったものである。イオン加速電圧としては、プレチルト角を高く、配向秩序度を高くするために、１００Ｖ以上、２００Ｖ以下であることが好ましい。また同様に、プレチルト角と配向秩序度の観点から、イオンの照射角度θは４０〜５０°、特に４５〜５０°であることが好ましい。さらに、イオン照射時の真空度が１０^−１〜１０^−４torrであり、しかも、イオン照射口から配向膜１２までの距離Ｌが１ｍｍ以上３００ｍｍ以下であることが好ましい。
【００３７】
特に、液晶表示装置としては、配向膜１２の配向処理後の厚さが１０〜１００ｎｍの範囲内であることが、配向膜による電圧降下の影響を少なくし、しかも、充分な配向規制力を確保するために好ましい。
【００３８】
次に、上述のように配向処理された配向膜１２に対して、図１（ｂ）に示すように例えば、金属製のマスク１３をセットしてほぼ垂直方向からイオン照射を行う。この工程は、上記のパネル基板１０の表面上から不要な配向膜１２を除去するための配向膜除去工程である。このときのイオン加速電圧としては、配向処理を施す必要がないとともに、短時間で配向膜１２の除去を行うためには１０００Ｖ以上であることが好ましい。特に、１０００Ｖ以上１５００Ｖ以下であることが配向膜１２の除去速度を実用的な範囲にするとともに、表面構造１１へのダメージを与えない観点から望ましい。
【００３９】
配向膜のイオンビームによる除去は、イオンビームを主として配向膜を除去したい部分を中心に照射できるようにイオン源２１とパネル基板１０とを相対的に走査して行うことが好ましい。このようにすることによって、配向膜１２の不要部分を均一に除去することができる。
【００４０】
この工程では、イオンビームを配向膜１２の表面に対して垂直方向から照射することによって、配向膜１２とマスク１３との間隔が存在しても、マスク１３の平面パターンに対して精度良く一致した範囲で配向膜１２を除去できるとともに、イオンによる配向膜の除去効率を高めることができ、迅速に工程を完了させることができる。
【００４１】
図８には、イオン照射時のイオン加速電圧を変化させた場合の上記配向膜の除去率（％）を測定した結果を示す。ここでは、一例として配向膜の厚さは約５００オングストロームである。イオン電流密度は約２０μＡ／ｃｍ^２、イオン照射時間は約２０秒である。尚、ここで記載のイオン照射時間とは所定の個所に実質にイオンが照射される時間を示す。従って、イオン照射する場合は所定の幅を有するイオンビームを走査させながら所定の個所を２０秒照射しても良いし、あるいはイオンビームを走査させずに一度に所定の個所にビームを２０秒照射させても良い。この図から分かるように、イオン加速電圧が１０００Ｖ以上であれば配向膜をほぼ完全に除去できる。また、イオン加速電圧は１５００Ｖ以下であると基板の表面構造に損傷を与えずに配向膜を除去することができる。尚、イオン電流密度は１５μＡ／ｃｍ^２以上２５μＡ／ｃｍ^２以下であり、イオン照射時間が２０秒以上であればほぼ同様な結果が得られた。
【００４２】
図９には、イオン照射時のイオン電流密度を変化させた場合の上記と同じ配向膜の除去率（％）を測定した結果を示す。ここで、イオン加速速度は約２００Ｖ、イオン照射時間は約２０秒である。この図から分かるように、イオン電流密度が１００μＡ／ｃｍ^２以上であると配向膜をほぼ完全に除去できる。また、イオン電流密度が１５０μＡ／ｃｍ^２以下であると基板の表面構造に損傷を与えずに配向膜を除去できる。尚、イオン加速電圧は１５０Ｖ以上２５０Ｖ以下、イオン照射時間は２０秒以上であればほぼ同様な結果が得られた。
【００４３】
図１０には、イオン照射時の基板表面のイオン照射時間の平均値を変化させた場合の上記と同じ配向膜の除去率（％）を測定した結果を示す。ここで、イオン加速電圧は約２００Ｖ、イオン電流密度は約２０μＡ／ｃｍ^２である。イオン照射時間が１００秒を越えるとほぼ完全に配向膜が除去できる。尚、イオン加速電圧は１５０Ｖ以上２５０Ｖ以下、イオン電流密度は１５μＡ／ｃｍ^２以上２５μＡ／ｃｍ^２の場合同様な結果が得られた。
【００４４】
基板上の配向膜に配向処理を施すと共に、配向膜の不要部分を除去する方法としては、上記の説明にあるように配向処理工程と、配向膜除去工程とを順次に行っていく方法の他に、イオンビームを走査していく際に、配向膜の必要部分にはイオン照射による配向処理を施し、配向膜の不要部分にはイオン照射による膜除去処理を施すことによって、一工程で配向膜の処理をする方法がある。この方法は、配向膜の必要部分に対するイオン照射条件と、不要部分に対するイオン照射条件とを異ならせることによって実施できる。このときの配向膜の必要部分に対するイオン照射条件は上述の配向処理工程にて説明した条件を採用でき、配向膜の不要部分に対するイオン照射条件は上述の配向膜の除去工程に対する説明部分で記述した条件を採用できる。
【００４５】
なお、イオンビームの走査はイオンビームと基板のいずれを移動させることによっても行うことができる。また、このときの走査手順としては、基板上の配向膜の必要部分のみをまとめて先に走査した後にイオン照射条件を切り換えて配向膜の不要部分をまとめて走査することも可能であり、或いは、配向膜上にイオンビームを順次に走査していく際に、配向膜の必要部分の表面上にイオンビームが照射される期間と不要部分の表面上にイオンビームが照射されている期間とでイオンビームの照射条件を繰り返し切り換えるように制御することも可能である。
【００４６】
図５は、パネル基板１０の平面図である。パネル基板１０の内部に一点鎖線で示された矩形領域は液晶表示領域１０Ａであって、配向膜１２に対して配向処理を施す必要のある領域である。この液晶表示領域１０Ａの外側には図示点線で示すようにシール材が塗布される予定のシール領域１０Ｂであり、このシール領域１０Ｂには配向膜１２の素材や溶剤などが付着するとシールの接着強度が低下するため、配向膜１２を完全に除去する必要のある領域である。シール領域１０Ｂのさらに外側には駆動用ＩＣやフレキシブル配線基板などを実装する外部領域１Ｃであり、この領域においても、実装不良を防止するために配向膜１２を完全に除去する必要がある。したがって、上記の図１（ｂ）に示す工程では、マスク１３によって図５に示す液晶表示領域１０Ａにある配向膜１２の表面を完全に覆い隠し、液晶表示領域１０Ａの表面にイオンが照射されないようにして、シール領域１０Ｂ及び外部領域１０Ｃの配向膜１２を完全に除去する。
【００４７】
本実施形態は、特に、液晶プロジェクタなどの投射型表示装置のライトバルブに用いる高精細な液晶パネルを製造する場合に特に効果的である。高精細な液晶パネルでは配向不良などの影響が大きいとともに、塵埃などの存在によって表示品位が大きく損なわれるとともに、シール領域や外部領域から配向素材を完全になくすことが印刷法などでは困難であるからである。
【００４８】
図６は、本実施形態を適用したＴＦＴ素子を備えたアクティブマトリクス型の液晶パネルの素子基板上の表面構造の平面パターンを示し、図７は図６のＸ−Ｘ線に沿って切断した基板断面構造を示すものである。素子基板上には走査線１０１とデータ線１０３が縦横にそれぞれ並列するように形成され、走査線１０１は画素毎に形成されたＴＦＴ１０４のゲートに接続され、ＴＦＴ１０４のソースはデータ線１０３に接続されている。ＴＦＴ１０４のドレインは画素電極１０６に電気的接続されているとともに蓄積容量１０５に電気的接続されている。蓄積容量１０５は容量線１０２に接続されている。この蓄積容量１０５を形成する方法としては、容量線１０２の代わりに前段の走査線１０１との間に接続してもよい。ＴＦＴ１０４は図６に斜線にて示す領域に延在し、ソース１０４１はデータ線１０３に対して開口部１０４１ａにて導電接続され、ゲート１０４２は走査線１０１と交差して図示しない薄い絶縁膜を介して対向する。ドレイン１０４３は開口部１０４３ａを介して画素電極１０６と導電接続される。これらの構造から延在した下電極１０４０は容量線１０２と絶縁層を介して平面的に重なり、上記蓄積容量１０５を構成している。蓄積容量１０５は、公知のように電荷のリークに対して画素電極１０６の電位を長時間保持するためのものである。
【００４９】
図６に示すような素子基板上に配向膜を形成し、配向処理を行う場合、従来のラビング法では、素子基板上の表面構造の凹凸（例えば配線部分が凸部となる。）によって凸部の際部などにおいて配向が充分になされない場合があり、配向不良が発生する可能性がある。特に、投射型表示装置に用いられる高精細な液晶パネルでは配向不良の部分が大きく画質に影響する。
【００５０】
これに対して、本実施形態では、ラビングによる発塵や洗浄の必要性をなくすことができ、表面の凹凸による配向不良の有無にも無縁である（４０〜５０°の傾斜角でイオンを照射しても配線の凹凸による影響はほとんど発生しないため、配向不良も抑制できる。）から、支障なく製造することができる。そして、イオン照射によって配向膜の配向処理と、不要部分の除去の２つの処理を行うことができるので、生産性が向上し、製造コストも低減できる。
【００５１】
上記実施形態では、配向処理のためのイオン照射工程と、不要部分除去のためのイオン照射工程とを連続して行っているが、必ずしも連続して行う必要はなく、両工程の間に他の処理を挟んだり、或いは、両工程の間で一旦真空を解除してもよい。また、両工程の順序を逆にして行ってもよい。
【００５２】
上記両工程を同じ装置内にて連続して行うには、イオン照射装置内にマスクを交換したり、マスクを繰り出したり待避させたりする機構と、イオンビームの照射方向とパネル基板のパネル面との角度を変える機構とを設ける必要がある。この場合、イオン照射条件としては、両工程においてそれぞれ最適な条件で行うことが望ましい。例えば、不要な配向膜除去工程では４０〜５０°の傾斜角のままでも、電圧、電流密度、時間（送り速度）、真空度、イオン種の調整により除去が可能である。
【００５３】
【発明の効果】
以上説明したように本発明によれば、イオン照射によって配向膜の配向処理と不要部分の除去とを共に行うことができるので、印刷法において問題となる周囲部分への配向素材の付着を回避できると同時に、製造時の手間を低減して生産性を高めることができ、液晶装置の品位低下を抑制しながら製造コストの低減を図ることが可能である。
【図面の簡単な説明】
【図１】本発明に係る液晶装置の製造方法の実施形態における配向処理工程を示す模式的な説明図（ａ）及び配向膜除去工程を示す模式的な説明図（ｂ）である。
【図２】同実施形態における配向膜へのイオン照射において、イオン加速電圧に対する液晶のプレチルト角及び配向秩序度の変化を示すグラフである。
【図３】同実施形態における配向膜へのイオン照射において、照射角度に対するプレチルト角及び配向秩序度の変化を示すグラフである。
【図４】同実施形態における配向膜へのイオン照射において、真空度に対する配向秩序度の変化をイオン照射口から配向膜までの距離Ｌ毎に示すグラフである。
【図５】パネル面上の各領域を示すためのパネル基板の平面図である。
【図６】液晶パネルの素子基板上の表面構造の平面パターンを示す拡大平面図である。
【図７】図６のＸ−Ｘ線に沿って切断した場合の素子基板の断面構造を示す拡大断面図である。
【図８】イオン照射時のイオン加速電圧を変化させた場合の配向膜の除去率を示すグラフである。
【図９】イオン照射時のイオン電流密度を変化させた場合の配向膜の除去率を示すグラフである。
【図１０】イオン照射時のイオン照射時間を変化させた場合の配向膜の除去率を示すグラフである。
【符号の説明】
１０ パネル基板
１１ 表面構造
１２ 配向膜
１３ マスク
２１ イオン源
２２ 加速電極[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a liquid crystal device, and more particularly to a process technique related to an alignment film for aligning an inner surface of a substrate.
[0002]
[Prior art]
Conventionally, when manufacturing a liquid crystal display panel as a liquid crystal device, for example, wiring, an electrode structure, an active element, etc. are formed on the inner surfaces of two panel substrates, and an alignment film made of an organic or inorganic material is formed thereon. Form. The alignment film has a function of aligning liquid crystal molecules in a predetermined direction by contacting a liquid crystal layer sandwiched between two panel substrates.
[0003]
There are various alignment films, but the most frequently used alignment films are made of organic materials such as polyimide resin and polyvinyl alcohol. In many cases, the alignment film made of these organic materials is formed by coating on the inner surface of the panel substrate and then curing it by drying or baking. After forming the alignment film, it is necessary to perform an alignment process such as a rubbing process.
[0004]
Conventionally, as a well-known alignment treatment method, there is a rubbing method in which the surface of an alignment film is rubbed in a predetermined direction with fibers or fabrics. However, since this method mechanically rubs the surface of the alignment film, it tends to generate dust during rubbing, so a cleaning process is required after rubbing. If dust remains, liquid crystal characteristics deteriorate and rubbing causes static electricity. Since it tends to occur, there is a risk that the liquid crystal alignment may be disturbed by static electricity, or an active element such as a TFT (thin film transistor) element or a two-terminal nonlinear element may be destroyed.
[0005]
Accordingly, various alignment treatment methods other than the rubbing method have been proposed. As this type of alignment treatment method, there are known a method of irradiating the surface of the alignment film with linearly polarized ultraviolet rays in a predetermined direction, a method of irradiating an ion beam or ultraviolet rays with inclination to the alignment film surface, and the like ing.
[0006]
As a method for forming an alignment film, which is a precondition for the alignment treatment, a method in which an alignment film material is selectively applied on a substrate by flexographic printing or the like, and then dried or baked is the mainstream. This is because the sealing material is applied to the substrate surface immediately outside the liquid crystal encapsulating region later in the substrate bonding process, so it is necessary to remove the alignment film in order to apply the sealing material on the substrate with high adhesion. It is because it becomes. Further, outside the seal portion, there is a portion for mounting an IC for driving liquid crystal, a flexible circuit board, etc., and this portion also needs to remove the alignment film.
[0007]
[Problems to be solved by the invention]
However, in the method of selectively applying the alignment material onto the inner surface of the substrate by printing as described above, it is difficult to reduce the manufacturing cost due to the time and effort required for the application, and the seal portion and the IC due to the bleeding of the printing or the like. There is a possibility that the alignment material adheres to the mounting portion, which may cause insufficient bonding strength of the panel substrate, poor mounting of the IC, and the like. Further, in a substrate having a large step, such as a TFT substrate, unevenness due to printing may occur, resulting in poor alignment.
[0008]
On the other hand, in the method of removing the unnecessary portion of the alignment film after coating the alignment material on the entire surface, the application of the alignment material itself is easy and does not cost, but the process for removing the alignment film on the outer periphery of the substrate There is a problem that the manufacturing cost is disadvantageous compared with the printing method.
[0009]
Therefore, the present invention solves the above-mentioned problems, and the problem is that the orientation material is prevented from adhering to the seal portion, the mounting portion, etc., leading to defects, and improving productivity and reducing manufacturing costs. An object of the present invention is to provide a method of manufacturing a liquid crystal device that can be used.
[0010]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the means taken by the present invention is a method of manufacturing a liquid crystal device in which a liquid crystal is arranged between two substrates. The surface of an alignment film formed on at least one inner surface of the substrate And an alignment treatment step for aligning by ion irradiation, and an alignment film removing step for selectively removing unnecessary portions of the alignment film by ion irradiation.
[0011]
According to this means, alignment treatment of the alignment film and removal of unnecessary portions can be performed together by ion irradiation, so that it is possible to avoid alignment material adhesion to surrounding portions, which is a problem in the printing method, and at the time of manufacture. It is possible to increase the productivity by reducing the labor of manufacturing, and it is possible to reduce the manufacturing cost while suppressing the deterioration of the quality of the liquid crystal device. In ion irradiation, a predetermined alignment process can be performed with a relatively small irradiation energy, and the alignment film can be easily removed by using a relatively large irradiation energy. As ion species to be irradiated, there are inert gas ions such as Ar.
[0012]
In the first aspect of the present invention, in the alignment film removing step, it is preferable to irradiate the ion beam by disposing a mask that covers a necessary portion of the alignment film between the ion source and the surface of the alignment film. Since the mask covers the necessary portion of the alignment film, damage to the required portion of the alignment film and disorder of the alignment treatment state due to ion beam irradiation can be prevented. The mask preferably does not transmit ions such as metal in order to block ions.
[0013]
In the first or second aspect, in the alignment film removing step, it is preferable to irradiate an ion beam from a direction intersecting a surface of the alignment film. In the alignment film removal process, the ion beam is irradiated from the direction that intersects the surface of the alignment film, preferably from a substantially orthogonal direction, so that it is difficult to cause damage to necessary portions of the alignment film due to mask displacement and the removal pattern is highly accurate. The removal rate can be increased by increasing the irradiation impact of irradiated ions.
[0014]
4. The alignment film removing process according to claim 1, wherein, in the alignment film removing step, the ion source and the substrate including the alignment film are relatively aligned in a direction substantially parallel to a surface of the alignment film. It is preferable to perform ion irradiation while moving. According to this means, it is possible to ensure local uniformity of the removal rate of the alignment film.
[0015]
In any one of claims 1 to 3, in the alignment layer removing step, the ion current density of 15 .mu.A / cm ² or more 25 .mu.A / cm ^2, where the ion irradiation time is 20 seconds or more, the ion acceleration rate 1000V The voltage is preferably 1500 V or less. With this configuration, the alignment film can be removed almost completely without damaging the surface structure of the substrate.
[0016]
4. The ion current density (μA / cm ² ) according to claim 1, wherein, in the alignment film removing step, when the ion acceleration voltage is 150 V or more and 250 V or less and the ion irradiation time is 20 seconds or more. It is preferable that it is 100 or more and 150 or less. With this configuration, the alignment film can be removed almost completely without damaging the surface structure of the substrate.
[0017]
^{2. The} ion irradiation time according to claim 1, wherein, in the alignment film removing step, when the ion current density is 15 μA / cm ² or more and 25 μA / cm ² and the ion acceleration voltage is 150 V or more and 250 V or less, the ion irradiation time is 100 seconds. The above is preferable. With this configuration, the alignment film can be removed almost completely without damaging the surface structure of the substrate.
[0018]
7. The ion acceleration voltage according to claim 1, wherein the ion accelerating voltage is 100 to 200 V with respect to a normal line of the alignment film in the alignment treatment step.
Chamber vacuum degree 10 ^-1 to 10 ^-4 torr
Ion irradiation is preferably performed under irradiation conditions of an ion irradiation angle of 40 to 50 degrees (more preferably 45 to 50 degrees). According to this configuration, the pretilt angle is high and the alignment order can be increased.
[0019]
8. The method according to claim 1, further comprising a step of coating the entire surface of the alignment film on the inner surface of the substrate before the alignment process step and the alignment film removal step. . By coating the entire surface of the alignment film on the substrate, the coating process can be simplified and the productivity can be improved. For example, a spin coating method that is relatively time-consuming can be used.
[0020]
In any one of Claims 1-8, it is desirable to perform the said alignment process process and the said alignment film removal process continuously within the same ion irradiation apparatus. By continuously performing both steps in the same ion irradiation apparatus, it is possible to further improve productivity and reduce management and work labor.
[0021]
The alignment film removing step may be performed after performing the alignment treatment step in any one of claims 1 to 9. It is also possible to reverse the order of both steps.
[0022]
In any one of Claims 1-10, in the said alignment process process, it is preferable to irradiate an ion beam from the direction inclined by the predetermined angle toward the predetermined direction with respect to the surface of the said alignment film. In this case, it is desirable to adopt each condition described in detail in an embodiment described later as the alignment treatment condition by ion irradiation.
[0023]
Next, in a method for manufacturing a liquid crystal device in which liquid crystal is disposed between two substrates, the method includes an ion irradiation step of performing ion irradiation on the surface of an alignment film formed on at least one inner surface of the substrate, In the ion irradiation step, an ion beam or the substrate is scanned to perform an alignment process on a necessary portion of the alignment film, and unnecessary portions of the alignment film are selectively removed by ion irradiation. According to this means, it is possible to perform the alignment process on the necessary portion of the alignment film and remove the unnecessary portion of the alignment film simply by changing the irradiation condition of the ion beam. Can be performed in one step.
[0024]
14. The irradiation according to claim 13, wherein a necessary portion of the alignment film is irradiated under a condition that the irradiation intensity or irradiation amount of the ion beam is small and an unnecessary portion of the alignment film is increased. Is preferred. In this case, the normal alignment film can be sufficiently removed by irradiating the unnecessary portion of the alignment film with ions under the conditions described in the following examples.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of a method for manufacturing a liquid crystal device according to the present invention will be described in detail. FIG. 1 is explanatory drawing (a) and (b) which showed the manufacturing process of this embodiment typically. In the present embodiment, first, after forming a required surface structure 11 such as a wiring, an electrode, and an active element on the surface of the panel substrate 10, an alignment material is entirely applied on the inner surface of the panel substrate 10 by a spin coating method or the like. Apply. As the alignment material, a soluble type polyimide material, a polyimide material that requires polymerization and curing, a polyamic acid type polyimide material, or the like can be used. The soluble polyimide material can be subjected to an alignment treatment while being applied. Other alignment materials are usually cured by drying or baking.
[0026]
As a soluble type polyimide material,
[0027]
[Chemical 1]

[0028]
[Chemical formula 2]

[0029]
Are particularly suitable for realizing a high voltage holding ratio, uniform liquid crystal alignment and a high pretilt angle.
[0030]
In addition, as a polyamic acid type polyimide material,
[0031]
[Chemical 3]

[0032]
Some have the structure of the main chain.
[0033]
The panel substrate 10 having the alignment film 12 formed on the surface as described above was introduced into the chamber of the ion irradiation apparatus. Then, the chamber was evacuated, Ar ions were released from the ion source 21, accelerated by the acceleration electrode 22, and irradiated.
[0034]
This ion irradiation is for performing alignment treatment on the alignment film 12. The degree of vacuum at this time was 5 × 10 ⁻³ torr, the ion irradiation angle was θ = 45 °, and Ar ions were irradiated under the conditions of an acceleration voltage of 100 V and a current density of 20 μA / cm ² . In addition, under this irradiation condition, the panel substrate 10 is oriented in the direction indicated by the arrow (that is, the direction parallel to (included in) the panel surface of the panel substrate 10 and the ion source 21 is inclined with respect to the panel surface. The alignment treatment was carried out while moving (scanning) at a speed of 1 cm / second in the direction toward the surface. Of course, the ion source 21 may be scanned instead of the panel substrate 10.
[0035]
The ion irradiation conditions in the alignment treatment are the relationship between the ion acceleration voltage shown in FIG. 2, the pretilt angle of the liquid crystal molecules, and the degree of alignment order (data when the ion irradiation angle is 45 °), and FIG. The relationship between the irradiation angle shown, the pretilt angle, and the degree of orientation order (data when the ion acceleration voltage is 100 V), the relationship between the degree of vacuum and the degree of orientation order shown in FIG. It is preferable that the acceleration voltage is 100 V and the distance from the ion irradiation port to the alignment film 12 is L.
[0036]
Here, the pretilt angle is an angle of the liquid crystal molecules in contact with the alignment film 12, and the 180 ° alignment treatment direction is determined by using the magnetic field potential method described in “Liquid Crystal Application” (Co-edited by Mitsuji Okano / Yusuke Kobayashi), page 63. Measurements were taken with different anti-parallel liquid crystal cells. The degree of orientational order is measured using GH (guest host) liquid crystal described on page 28 of the same book, and is averaged over an area range of at least 1 cm ² or more. The ion acceleration voltage is preferably 100 V or more and 200 V or less in order to increase the pretilt angle and increase the degree of alignment order. Similarly, from the viewpoint of the pretilt angle and the degree of orientation order, the ion irradiation angle θ is preferably 40 to 50 °, particularly 45 to 50 °. Furthermore, the degree of vacuum at the time of ion irradiation is preferably 10 ⁻¹ to 10 ⁻⁴ torr, and the distance L from the ion irradiation port to the alignment film 12 is preferably 1 mm to 300 mm.
[0037]
In particular, for a liquid crystal display device, the thickness of the alignment film 12 after the alignment treatment is in the range of 10 to 100 nm, which reduces the influence of voltage drop due to the alignment film and ensures sufficient alignment regulating power. This is preferable.
[0038]
Next, as shown in FIG. 1B, for example, a metal mask 13 is set on the alignment film 12 subjected to the alignment treatment as described above, and ion irradiation is performed from a substantially vertical direction. This process is an alignment film removing process for removing the unnecessary alignment film 12 from the surface of the panel substrate 10 described above. The ion accelerating voltage at this time is preferably 1000 V or higher in order to remove the alignment film 12 in a short period of time without performing an alignment treatment. In particular, the voltage is preferably 1000 V or more and 1500 V or less from the viewpoint of making the removal rate of the alignment film 12 within a practical range and not damaging the surface structure 11.
[0039]
The removal of the alignment film by the ion beam is preferably performed by relatively scanning the ion source 21 and the panel substrate 10 so that the ion beam can be mainly irradiated around the portion where the alignment film is desired to be removed. By doing in this way, the unnecessary part of the alignment film 12 can be removed uniformly.
[0040]
In this step, by irradiating the ion beam from the direction perpendicular to the surface of the alignment film 12, even if there is a gap between the alignment film 12 and the mask 13, the plane pattern of the mask 13 is accurately matched. The alignment film 12 can be removed within a range, and the removal efficiency of the alignment film by ions can be increased, and the process can be completed quickly.
[0041]
FIG. 8 shows the result of measuring the removal rate (%) of the alignment film when the ion acceleration voltage at the time of ion irradiation is changed. Here, as an example, the thickness of the alignment film is about 500 angstroms. The ion current density is about 20 μA / cm ² , and the ion irradiation time is about 20 seconds. In addition, the ion irradiation time described here indicates a time during which ions are substantially irradiated to a predetermined portion. Accordingly, when ion irradiation is performed, a predetermined portion may be irradiated for 20 seconds while scanning an ion beam having a predetermined width, or a predetermined portion may be irradiated for 20 seconds at a time without scanning the ion beam. You may let them. As can be seen from this figure, when the ion acceleration voltage is 1000 V or more, the alignment film can be almost completely removed. Further, when the ion acceleration voltage is 1500 V or less, the alignment film can be removed without damaging the surface structure of the substrate. The ion current density is 15 .mu.A / cm ² or more 25 .mu.A / cm ² or less, almost the same results were obtained if the ion irradiation time 20 seconds or more.
[0042]
FIG. 9 shows the result of measuring the removal rate (%) of the same alignment film as described above when the ion current density during ion irradiation is changed. Here, the ion acceleration speed is about 200 V, and the ion irradiation time is about 20 seconds. As can be seen from this figure, when the ion current density is 100 μA / cm ² or more, the alignment film can be almost completely removed. Further, when the ion current density is 150 μA / cm ² or less, the alignment film can be removed without damaging the surface structure of the substrate. Note that substantially the same results were obtained when the ion acceleration voltage was 150 V to 250 V and the ion irradiation time was 20 seconds or more.
[0043]
FIG. 10 shows the result of measuring the removal rate (%) of the same alignment film as described above when the average value of the ion irradiation time on the substrate surface during ion irradiation is changed. Here, the ion acceleration voltage is about 200 V, and the ion current density is about 20 μA / cm ² . When the ion irradiation time exceeds 100 seconds, the alignment film can be almost completely removed. Incidentally, the ion acceleration voltage is 150V to 250V, the ion current density when similar results of 15 .mu.A / cm ² or more 25 .mu.A / cm ² was obtained.
[0044]
As a method for performing an alignment process on the alignment film on the substrate and removing unnecessary portions of the alignment film, as described above, an alignment process step and an alignment film removal step are sequentially performed. In addition, when the ion beam is scanned, the alignment film is subjected to alignment treatment by ion irradiation on the necessary portion of the alignment film, and the unnecessary portion of the alignment film is subjected to film removal treatment by ion irradiation, thereby performing the alignment film in one step. There is a method of processing. This method can be carried out by making the ion irradiation conditions for the necessary portions of the alignment film different from the ion irradiation conditions for the unnecessary portions. The ion irradiation conditions for the necessary part of the alignment film at this time can adopt the conditions described in the above-described alignment treatment step, and the ion irradiation conditions for the unnecessary part of the alignment film are described in the description part for the above-described alignment film removal process. Conditions can be adopted.
[0045]
Note that the scanning of the ion beam can be performed by moving either the ion beam or the substrate. Further, as a scanning procedure at this time, it is also possible to scan only unnecessary portions of the alignment film on the substrate and scan the unnecessary portions of the alignment film collectively by switching the ion irradiation conditions after scanning first, or When the ion beam is sequentially scanned on the alignment film, the ion beam is irradiated on the surface of the necessary part of the alignment film and the ion beam is irradiated on the surface of the unnecessary part. It is also possible to control so that the ion beam irradiation conditions are switched repeatedly.
[0046]
FIG. 5 is a plan view of the panel substrate 10. A rectangular area indicated by a one-dot chain line inside the panel substrate 10 is a liquid crystal display area 10 </ b> A, which is an area where the alignment film 12 needs to be subjected to an alignment process. Outside the liquid crystal display area 10A is a seal area 10B where a sealing material is to be applied as shown by the dotted line in the figure. When the material of the alignment film 12 or a solvent adheres to the seal area 10B, the adhesive strength of the seal Therefore, the alignment film 12 needs to be completely removed. Further outside the seal region 10B is an external region 1C for mounting a driving IC, a flexible wiring board, and the like. In this region as well, it is necessary to completely remove the alignment film 12 in order to prevent mounting defects. Therefore, in the process shown in FIG. 1B, the surface of the alignment film 12 in the liquid crystal display region 10A shown in FIG. 5 is completely covered by the mask 13 so that the surface of the liquid crystal display region 10A is not irradiated with ions. Thus, the alignment film 12 in the seal region 10B and the outer region 10C is completely removed.
[0047]
This embodiment is particularly effective when a high-definition liquid crystal panel used for a light valve of a projection display device such as a liquid crystal projector is manufactured. High-definition liquid crystal panels are greatly affected by poor alignment, and the display quality is greatly impaired by the presence of dust, etc., and it is difficult to completely eliminate alignment materials from the seal area and external area by printing methods. It is.
[0048]
FIG. 6 shows a plane pattern of the surface structure on the element substrate of the active matrix type liquid crystal panel provided with the TFT element to which this embodiment is applied, and FIG. 7 shows the substrate cut along the line XX in FIG. A cross-sectional structure is shown. On the element substrate, the scanning line 101 and the data line 103 are formed so as to be parallel in the vertical and horizontal directions, the scanning line 101 is connected to the gate of the TFT 104 formed for each pixel, and the source of the TFT 104 is connected to the data line 103. ing. The drain of the TFT 104 is electrically connected to the pixel electrode 106 and is also electrically connected to the storage capacitor 105. The storage capacitor 105 is connected to the capacitor line 102. As a method for forming the storage capacitor 105, the storage capacitor 105 may be connected to the preceding scanning line 101 instead of the capacitor line 102. The TFT 104 extends in a hatched area in FIG. 6, the source 1041 is conductively connected to the data line 103 through the opening 1041a, and the gate 1042 intersects the scanning line 101 via a thin insulating film (not shown). Facing each other. The drain 1043 is conductively connected to the pixel electrode 106 through the opening 1043a. The lower electrode 1040 extending from these structures overlaps the capacitor line 102 in a plan view via the insulating layer, and constitutes the storage capacitor 105. The storage capacitor 105 is for holding the potential of the pixel electrode 106 for a long time against charge leakage as is well known .
[0049]
In the case where an alignment film is formed on an element substrate as shown in FIG. 6 and alignment processing is performed, in the conventional rubbing method, convex portions are formed by irregularities in the surface structure on the element substrate (for example, wiring portions become convex portions). In such a case, the alignment may not be sufficiently performed in the portion at the time, and alignment failure may occur. In particular, in a high-definition liquid crystal panel used in a projection display device, a poorly aligned portion greatly affects the image quality.
[0050]
On the other hand, in the present embodiment, it is possible to eliminate the need for dust generation and cleaning by rubbing, and there is no alignment defect due to surface irregularities (irradiation with ions at an inclination angle of 40 to 50 °). However, since the influence of the unevenness of the wiring hardly occurs, the orientation failure can be suppressed. And since two processes of alignment process of an alignment film and removal of an unnecessary part can be performed by ion irradiation, productivity improves and manufacturing cost can also be reduced.
[0051]
In the above embodiment, the ion irradiation process for the alignment treatment and the ion irradiation process for removing the unnecessary portion are continuously performed. However, the ion irradiation process is not necessarily performed continuously. The process may be sandwiched, or the vacuum may be released once between both processes. Further, the order of both steps may be reversed.
[0052]
In order to carry out both of the above processes in the same apparatus continuously, a mechanism for exchanging the mask in the ion irradiation apparatus, a mechanism for extending and retracting the mask, an ion beam irradiation direction and a panel surface of the panel substrate It is necessary to provide a mechanism for changing the angle. In this case, as ion irradiation conditions, it is desirable to carry out under optimum conditions in both steps. For example, in the unnecessary alignment film removal step, even if the inclination angle is 40 to 50 °, the removal can be performed by adjusting the voltage, current density, time (feed rate), vacuum degree, and ion species.
[0053]
【The invention's effect】
As described above, according to the present invention, alignment treatment of the alignment film and removal of unnecessary portions can be performed together by ion irradiation, so that it is possible to avoid adhesion of alignment materials to surrounding portions, which is a problem in the printing method. At the same time, it is possible to increase the productivity by reducing labor during manufacturing, and it is possible to reduce the manufacturing cost while suppressing the deterioration of the quality of the liquid crystal device.
[Brief description of the drawings]
FIG. 1A is a schematic explanatory view showing an alignment treatment step in an embodiment of a method for manufacturing a liquid crystal device according to the present invention, and FIG. 1B is a schematic explanatory view showing an alignment film removal step.
FIG. 2 is a graph showing changes in pretilt angle and orientation degree of liquid crystal with respect to ion acceleration voltage in ion irradiation of the alignment film in the same embodiment.
FIG. 3 is a graph showing changes in pretilt angle and orientation order with respect to the irradiation angle in ion irradiation on the alignment film in the same embodiment;
FIG. 4 is a graph showing changes in the degree of alignment order with respect to the degree of vacuum for each distance L from the ion irradiation port to the alignment film in the ion irradiation to the alignment film in the same embodiment.
FIG. 5 is a plan view of a panel substrate for showing each region on the panel surface.
FIG. 6 is an enlarged plan view showing a planar pattern of the surface structure on the element substrate of the liquid crystal panel.
7 is an enlarged cross-sectional view showing a cross-sectional structure of the element substrate when cut along the line XX in FIG. 6;
FIG. 8 is a graph showing the removal rate of the alignment film when the ion acceleration voltage at the time of ion irradiation is changed.
FIG. 9 is a graph showing the removal rate of the alignment film when the ion current density during ion irradiation is changed.
FIG. 10 is a graph showing the removal rate of the alignment film when the ion irradiation time during ion irradiation is changed.
[Explanation of symbols]
10 Panel substrate 11 Surface structure 12 Alignment film 13 Mask 21 Ion source 22 Accelerating electrode

Claims (14)

In a method of manufacturing a liquid crystal device in which liquid crystal is disposed between two substrates, an alignment treatment step of aligning the surface of an alignment film formed on at least one inner surface of the substrate by ion irradiation, and the alignment An alignment film removing step of selectively removing unnecessary portions of the film by ion irradiation,
A method of manufacturing a liquid crystal device, wherein the alignment treatment step and the alignment film removal step are performed in the same ion irradiation apparatus.   2. The alignment film removing step according to claim 1, wherein in the alignment film removing step, a mask that covers a necessary portion of the alignment film is disposed between the ion source and the surface of the alignment film, and the ion beam is irradiated. A method for manufacturing a liquid crystal device.   3. The method for manufacturing a liquid crystal device according to claim 1, wherein in the alignment film removing step, an ion beam is irradiated from a direction intersecting the surface of the alignment film. In any one of claims 1 to 3, in the alignment layer removing step, the ion current density of 15 .mu.A / cm ² or more 25 .mu.A / cm ^2,
When the ion irradiation time is 20 seconds or more, the ion acceleration speed is 1000 V or more and 1500 V or less. 4. The ion current density (μA / cm ² ) according to claim 1, wherein, in the alignment film removing step, when the ion acceleration voltage is 150 V or more and 250 V or less and the ion irradiation time is 20 seconds or more. A method for manufacturing a liquid crystal device, which is 100 to 150. In any one of claims 1 to 3, in the alignment layer removing step, the ion current density of 15 .mu.A / cm ² or more 25 .mu.A / cm ^2,
A method of manufacturing a liquid crystal device, wherein the ion irradiation time is 100 seconds or more when the ion acceleration voltage is 150 V or more and 250 V or less. 7. The method for manufacturing a liquid crystal device according to claim 1, wherein, in the alignment treatment step, ion irradiation is performed with respect to a normal line of the alignment film under the following conditions.
Ion acceleration voltage 100-200V
Chamber vacuum degree 10 ^-1 to 10 ^-4 torr
Ion irradiation angle 40-50 degrees   8. The alignment film removing step according to claim 1, wherein in the alignment film removing step, the ion source and the substrate provided with the alignment film are relatively aligned in a direction substantially parallel to a surface of the alignment film. A method for manufacturing a liquid crystal device, characterized in that ion irradiation is performed while being moved.   The method according to any one of claims 1 to 8, further comprising a step of applying the alignment film on an inner surface of the substrate before the alignment treatment step and the alignment film removal step. A method for manufacturing a liquid crystal device.   10. The method of manufacturing a liquid crystal device according to claim 1, wherein the alignment treatment step and the alignment film removal step are continuously performed in the same ion irradiation apparatus. 11.   11. The method of manufacturing a liquid crystal device according to claim 1, wherein the alignment film removing step is performed after the alignment treatment step.   12. The alignment processing step according to claim 1, wherein in the alignment treatment step, an ion beam is irradiated from a direction inclined at a predetermined angle toward a predetermined direction with respect to a surface of the alignment film. A method for manufacturing a liquid crystal device. In a method of manufacturing a liquid crystal device in which a liquid crystal is arranged between two substrates, the method includes an ion irradiation step of irradiating ions on the surface of an alignment film formed on at least one inner surface of the substrate. The process includes a step of performing an alignment process on a necessary portion of the alignment film by an ion beam and selectively removing unnecessary portions of the alignment film by ion irradiation.
The method for manufacturing a liquid crystal device, wherein the alignment treatment and the removal are performed in the same ion irradiation apparatus.   14. The irradiation according to claim 13, wherein a necessary portion of the alignment film is irradiated under a condition that the irradiation intensity or irradiation amount of the ion beam is small and an unnecessary portion of the alignment film is increased. A method of manufacturing a liquid crystal device.

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