JPH0544016B2 - - Google Patents
Info
- Publication number
- JPH0544016B2 JPH0544016B2 JP24665487A JP24665487A JPH0544016B2 JP H0544016 B2 JPH0544016 B2 JP H0544016B2 JP 24665487 A JP24665487 A JP 24665487A JP 24665487 A JP24665487 A JP 24665487A JP H0544016 B2 JPH0544016 B2 JP H0544016B2
- Authority
- JP
- Japan
- Prior art keywords
- film
- light
- photomask
- mask substrate
- metal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 239000000758 substrate Substances 0.000 claims description 35
- 230000001681 protective effect Effects 0.000 claims description 13
- 239000010408 film Substances 0.000 description 83
- 229910052751 metal Inorganic materials 0.000 description 37
- 239000002184 metal Substances 0.000 description 37
- 229910004298 SiO 2 Inorganic materials 0.000 description 13
- 239000010410 layer Substances 0.000 description 7
- 239000010409 thin film Substances 0.000 description 7
- 239000011521 glass Substances 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- 230000003287 optical effect Effects 0.000 description 6
- 230000009993 protective function Effects 0.000 description 4
- 239000000956 alloy Substances 0.000 description 3
- 229910045601 alloy Inorganic materials 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000010453 quartz Substances 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 3
- 229910010413 TiO 2 Inorganic materials 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000005530 etching Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052761 rare earth metal Inorganic materials 0.000 description 2
- HUAUNKAZQWMVFY-UHFFFAOYSA-M sodium;oxocalcium;hydroxide Chemical compound [OH-].[Na+].[Ca]=O HUAUNKAZQWMVFY-UHFFFAOYSA-M 0.000 description 2
- 229910052723 transition metal Inorganic materials 0.000 description 2
- 150000003624 transition metals Chemical class 0.000 description 2
- 238000004506 ultrasonic cleaning Methods 0.000 description 2
- 229910016006 MoSi Inorganic materials 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 229920002120 photoresistant polymer Polymers 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は、例えば、レーザ等の光にて情報の記
録、再生および消去等を行う光メモリ素子の光露
光方式による製造に供されるフオトマスクに関す
るものである。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a photomask used for manufacturing an optical memory element using a light exposure method, which records, reproduces and erases information using light such as a laser. It is something.
この種の従来のフオトマスクは、第２図に示す
ように、透光性のマスク基板１１に、マスクパタ
ンを形成する遮光性のTa，Cr，Ti等の金属膜１
２……が埋設されたもの、或いは、第３図に示す
ように、マスク基板１１の表面に金属膜１２……
設けられたものに大別される。このようなフオト
マスクを、例えば、光メモリの案内溝の形成に使
用する際には、その案内溝の寸法が、一般に0.6
〜1.3μmというように、サブミクロンオーダーで
あることにより、マスクパタンを正確にレジスト
に転写するために、フオトマスクをレジストに密
着させる密着転写が行われている。
This type of conventional photomask, as shown in FIG.
2... is embedded, or as shown in FIG. 3, a metal film 12... is buried on the surface of the mask substrate 11.
It is broadly divided into those that have been established. When such a photomask is used, for example, to form a guide groove for an optical memory, the dimensions of the guide groove are generally 0.6
Since the mask pattern is on the submicron order of ~1.3 μm, contact transfer is performed in which the photomask is brought into close contact with the resist in order to accurately transfer the mask pattern onto the resist.
ところが、上記の密着転写の際には、フオトマ
スクへのレジストの付着、或いは、レジストとフ
オトマスクとの間へのごみの介入等により、しば
しばフオトマスクに汚れが発生する。そして、汚
れたフオトマスクは超音波洗浄されるが、この際
に、金属膜１２……の剥がれが生じ、マスクパタ
ンの一部が欠損するという不都合を招来してい
る。 However, during the above-mentioned close-contact transfer, stains often occur on the photomask due to adhesion of the resist to the photomask or dirt entering between the resist and the photomask. The dirty photomask is then subjected to ultrasonic cleaning, but at this time, the metal film 12... peels off, resulting in the inconvenience that part of the mask pattern is missing.
また、例えば特公昭50−23595号公報には、マ
スク基板上に金属膜が突出して設けられ、さら
に、フオトマスクの耐用性の向上や、金属膜の反
射率の低下を目的として、上記金属膜を覆う被覆
薄膜層が形成されたフオトマスクが開示されてい
る。 Further, for example, in Japanese Patent Publication No. 50-23595, a metal film is provided protrudingly on a mask substrate, and the metal film is further provided for the purpose of improving the durability of the photomask and reducing the reflectance of the metal film. A photomask is disclosed that has a covering thin film layer formed thereon.
このように、マスク基板上に設けられた金属膜
を覆う被覆膜層を形成すると、前記したフオトマ
スク洗浄時における金属膜の剥がれを防止するこ
とができ、マスクパタンに欠損が生じるのを防ぐ
ことが可能になる。 In this way, by forming a coating layer that covers the metal film provided on the mask substrate, it is possible to prevent the metal film from peeling off during the photomask cleaning described above, and to prevent defects from occurring in the mask pattern. becomes possible.
しかしながら、上記の場合には、マスク基板表
面から金属膜が突出して設けられているので、被
覆薄膜層は、金属膜によるマスク基板上の凹凸を
覆うように形成する必要がある。このため、上記
金属膜を確実に被覆するには、金属膜の厚みより
も、上記被覆薄膜層を厚くする必要があり、寸法
上の制約を受けることになる。また、被覆薄膜層
の膜厚が、金属膜の膜厚を下回ると、金属膜が露
出し、マスクパタンの欠損を生じる虞れがある。
However, in the above case, since the metal film is provided protruding from the surface of the mask substrate, the coating thin film layer needs to be formed so as to cover the irregularities on the mask substrate caused by the metal film. Therefore, in order to reliably cover the metal film, it is necessary to make the coating thin film layer thicker than the metal film, which results in dimensional restrictions. Furthermore, if the thickness of the coating thin film layer is less than the thickness of the metal film, the metal film may be exposed and the mask pattern may be damaged.
本発明のフオトマスクは、上記問題点を解決す
るために、透光性のマスク基板に、マスクパタン
を形成する遮光膜が上記マスク基板表面と同一平
面をなすように埋設され、上記遮光膜が埋設され
たマスク基板表面に、遮光膜を被覆する透光性の
保護膜が設けられている構成である。
In order to solve the above-mentioned problems, the photomask of the present invention has a light-shielding film forming a mask pattern embedded in a light-transmitting mask substrate so as to be flush with the surface of the mask substrate, and the light-shielding film is In this configuration, a light-transmitting protective film covering the light-shielding film is provided on the surface of the mask substrate.
上記の構成によれば、マスク基板に埋設されて
いる遮光膜は、マスク基板表面と同一平面をなし
ており、この平面上に保護膜が形成されるように
なつている。つまり、この保護膜は、遮光膜の膜
厚より多少薄くても、遮光膜が露出する虞れがな
く、遮光膜の保護機能を損なわない程度であれ
ば、それほど寸法上の制約を受けるものではな
い。したがつて、遮光膜は保護膜により確実に覆
われるので、フオトマスク洗浄時における遮光膜
の剥がれを確実に防止して、マスクパタンの欠損
を防ぐことが可能になる。
According to the above configuration, the light shielding film embedded in the mask substrate is flush with the surface of the mask substrate, and the protective film is formed on this plane. In other words, even if this protective film is somewhat thinner than the light-shielding film, as long as there is no risk of the light-shielding film being exposed and the protective function of the light-shielding film is not impaired, it is not subject to significant dimensional restrictions. do not have. Therefore, since the light-shielding film is reliably covered with the protective film, it is possible to reliably prevent the light-shielding film from peeling off during photomask cleaning, thereby preventing damage to the mask pattern.
本発明の一実施例を第１図に基づいて以下に説
明する。
An embodiment of the present invention will be described below based on FIG.
本発明に係るフオトマスクは、石英、ソーダラ
イム等からなる透光性のマスク基板１を有してい
る。このマスク基板１の上部には、遮光膜である
複数の金属膜２……が、上記マスク基板１表面と
同一平面をなすように埋設されている。この金属
膜２……はマスクパタンを形成すると共に、マス
ク基板１に照射される紫外線等の露光用の光を遮
断するようになつている。そして、金属膜２……
は、マスク基板１における金属膜２……の配設部
位をエツチングにて除去し、その部位に遮光性を
有するTa，Ti，Cr或いはMo等の金属材料、ま
たは、これらの材料を母材とする、例えばTaSi，
MoSi等の材料が設けられることによつて形成さ
れている。尚、上記の金属膜２……は、ネガ型レ
ジストを用いる場合には、現像によつてレジスト
が除去される部位に設けられ、ポジ型レジストを
用いる場合には、現像にてレジストが残る部位に
設けられる。 The photomask according to the present invention has a transparent mask substrate 1 made of quartz, soda lime, or the like. A plurality of metal films 2 serving as light shielding films are buried in the upper part of the mask substrate 1 so as to be flush with the surface of the mask substrate 1. These metal films 2 form a mask pattern and are designed to block exposure light such as ultraviolet rays irradiated onto the mask substrate 1. And metal film 2...
In this method, the portion of the mask substrate 1 where the metal film 2... is disposed is removed by etching, and a metal material such as Ta, Ti, Cr, or Mo that has a light-shielding property is removed in that portion, or these materials are used as a base material. For example, TaSi,
It is formed by providing a material such as MoSi. In addition, the above-mentioned metal film 2... is provided in a region where the resist is removed by development when a negative resist is used, and is provided in a region where the resist remains after development when a positive resist is used. established in
上記金属膜２……が埋設されたマスク基板１表
面には、保護膜である透光性のSiO2膜３が設け
られている。このSiO2膜３の膜厚は、30〜
300nm程度が望ましい。即ち、SiO2膜３は薄く
なり過ぎると、金属膜２……に対する保護機能が
低下する反面、厚くなり過ぎるとパタン転写の精
度が低下する。 A transparent SiO 2 film 3 serving as a protective film is provided on the surface of the mask substrate 1 in which the metal films 2 are embedded. The thickness of this SiO 2 film 3 is 30~
Approximately 300 nm is desirable. That is, if the SiO 2 film 3 becomes too thin, its protective function against the metal film 2 .
上記の構成において、本フオトマスクでは、
SiO2膜３にて金属膜２……が被覆されているこ
とにより、たとえば、超音波洗浄の際において
も、金属膜２……の剥がれが防止され、マスクパ
タンが保護されている。 In the above configuration, in this photomask,
By covering the metal films 2 with the SiO 2 film 3, the metal films 2 are prevented from peeling off even during ultrasonic cleaning, and the mask pattern is protected.
また、SiO2膜３は、石英、或いはソーダライ
ム等のガラス材料からなるマスク基板１に含まれ
るSiO2成分との密着性が良好であり、特に強靱
な保護膜となる。そして、石英からなるマスク基
板１にCrからなる金属膜２……にてマスクパタ
ンンを作製し、この金属膜２……をSiO2膜３に
て保護したマスクにて、光メモリ素子用案内溝を
転写した結果、SiO2膜３を設けていないフオト
マスクの場合には、数回の光メモリ素子への転写
にて、マスクパタンの欠損が発生したのに対し、
本フオトマスクでは、数千回の転写工程において
もパタン欠けが生じなかつた。 Further, the SiO 2 film 3 has good adhesion to the SiO 2 component contained in the mask substrate 1 made of a glass material such as quartz or soda lime, and becomes a particularly tough protective film. Then, a mask pattern is prepared on a mask substrate 1 made of quartz using a metal film 2 made of Cr, and a guide groove for an optical memory element is transferred using a mask that protects this metal film 2 with a SiO 2 film 3. As a result, in the case of a photomask without the SiO 2 film 3, defects in the mask pattern occurred after several transfers to the optical memory element.
With this photomask, no pattern chipping occurred even after several thousand transfer steps.
さらに、金属膜２……とマスク基板１とが同一
平面をなすように、金属膜２……がマスク基板１
に埋設されているので、金属膜２……の保護機能
を有するSiO2膜３は、この平面上に形成される。
したがつて、前記従来のように、マスク基板上に
金属膜が突出して設けられた凹凸状の表面に膜を
形成する場合と比較すると、本フオトマスクに形
成されるSiO2膜３は、上述した膜厚の範囲内で
あれば、それほど寸法上の制約を受けるものでは
ない。これにより、SiO2膜３の膜厚が、金属膜
２……の膜厚より薄い場合でも、金属膜２……が
露出する虞れが回避され、確実に金属膜２……を
保護することができる。 Further, the metal film 2... is placed on the mask substrate 1 so that the metal film 2... and the mask substrate 1 are on the same plane.
The SiO 2 film 3 having a protective function for the metal film 2 is formed on this plane.
Therefore, compared to the case where a film is formed on the uneven surface of a mask substrate with a protruding metal film as described above, the SiO 2 film 3 formed on the present photomask has the above-mentioned characteristics. As long as the film thickness is within the range, there are not many dimensional restrictions. As a result, even if the thickness of the SiO 2 film 3 is thinner than that of the metal film 2, the risk of the metal film 2 being exposed is avoided, and the metal film 2 is reliably protected. I can do it.
また、本フオトマスクは、光磁気デイスク等の
光メモリ素子の製造に適する。即ち、光磁気デイ
スクはメモリ媒体として、希土類元素と遷移金属
との合金薄膜を使用するのが一般的であるが、こ
の合金薄膜は、水分や酸素等によつて劣化し易い
という性質を有している。そこで、本フオトマス
クにより、光メモリ素子のガラス基板に案内溝パ
タンを露光して現象した後、エツチングにて直接
ガラス基板に案内溝を掘り込み、このガラス基板
上に、希土類元素と遷移金属との合金薄膜を形成
すると、ガラス基板を通じてメモリ媒体に達する
酸素や水分がないため、非常に信頼性の高いメモ
リ素子を得ることができる。 Further, this photomask is suitable for manufacturing optical memory elements such as magneto-optical disks. In other words, magneto-optical disks generally use an alloy thin film of rare earth elements and transition metals as a memory medium, but this alloy thin film has the property of being easily degraded by moisture, oxygen, etc. ing. Therefore, after exposing a guide groove pattern on the glass substrate of an optical memory element using this photomask to develop the phenomenon, guide grooves are dug directly into the glass substrate by etching, and an alloy of rare earth elements and transition metals is formed on the glass substrate. By forming a thin film, there is no oxygen or moisture reaching the memory medium through the glass substrate, making it possible to obtain a highly reliable memory element.
尚、本実施例では、保護膜としてSiO2膜３を
設けた例を示したが、これに限定されるものでは
なく、保護機能を有する透光性の膜であれば、他
の保護膜であつても構わないのは勿論である。そ
の材料としては、例えば、ＡＮ，SiN，TaN
等の窒化物、或いはＡ2O3，TiO2等の酸化物が
挙げられる。 Although this example shows an example in which the SiO 2 film 3 is provided as a protective film, the present invention is not limited to this, and any other protective film may be used as long as it is a transparent film that has a protective function. Of course, it doesn't matter if there is. Examples of the material include AN, SiN, TaN
Examples include nitrides such as A 2 O 3 and TiO 2 , and oxides such as A 2 O 3 and TiO 2 .
また、金属膜２は、前記した金属の単層膜、金
属とその金属の酸化物との二層膜、或いは三層以
上の複層膜としてもよい。さらに、遮光膜として
は、金属膜２に限定されるものではなく、遮光性
を有し、かつマスクパタンを形成し得る他の材料
からなるものであつてもよい。 Further, the metal film 2 may be a single-layer film of the metal described above, a two-layer film of a metal and an oxide of the metal, or a multi-layer film of three or more layers. Furthermore, the light-shielding film is not limited to the metal film 2, but may be made of other materials that have light-shielding properties and can form a mask pattern.
本発明のフオトマスクは、以上のように、透光
性のマスク基板に、マスクパタンを形成する遮光
膜が上記マスク基板表面と同一平面をなすように
埋設され、上記遮光膜が埋設されたマスク基板表
面に、遮光膜を被覆する透光性の保護膜が設けら
れている構成である。
As described above, the photomask of the present invention has a light-shielding film forming a mask pattern embedded in a light-transmitting mask substrate so as to be flush with the surface of the mask substrate, and a mask substrate in which the light-shielding film is embedded. It has a structure in which a light-transmitting protective film covering the light-shielding film is provided on the surface.
それゆえ、マスク基板に埋設されている遮光膜
はマスク基板表面と同一平面をなしており、保護
膜はこの平面上に形成されるので、保護膜の厚み
が遮光膜の厚みより薄い場合でも、遮光膜が露出
する虞れはなく、寸法上の制約を受けることはほ
とんどない。したがつて、確実に遮光膜を保護す
ることができるので、フオトマスクの寿命を延長
することが可能になり、このフオトマスクを利用
することにより、例えば、ガラス基板型光磁気デ
イスクの量産が容易になるという効果を奏する。 Therefore, the light-shielding film embedded in the mask substrate is on the same plane as the mask substrate surface, and the protective film is formed on this plane, so even if the thickness of the protective film is thinner than that of the light-shielding film, There is no risk that the light-shielding film will be exposed, and there are almost no dimensional restrictions. Therefore, the light-shielding film can be reliably protected, making it possible to extend the life of the photomask, and by using this photomask, for example, mass production of glass substrate type magneto-optical disks becomes easier. This effect is achieved.
第１図は本発明の一実施例を示す要部の縦断面
図、第２図は従来例を示す要部の縦断面図、第３
図は他の従来例を示す要部の縦断面図である。
１はマスク基板、２は金属膜（遮光膜）、３は
SiO2膜（保護膜）である。
FIG. 1 is a vertical cross-sectional view of the main part showing an embodiment of the present invention, FIG. 2 is a vertical cross-sectional view of the main part showing a conventional example, and FIG.
The figure is a longitudinal cross-sectional view of the main parts of another conventional example. 1 is a mask substrate, 2 is a metal film (light shielding film), 3 is a
It is a SiO 2 film (protective film).
Claims (1)
する遮光膜が上記マスク基板表面と同一平面をな
すように埋設され、上記遮光膜が埋設されたマス
ク基板表面に、遮光膜を被覆する透光性の保護膜
が設けられていることを特徴とするフオトマス
ク。1. A light-shielding film forming a mask pattern is embedded in a light-transmitting mask substrate so as to be flush with the surface of the mask substrate, and a light-transmitting film covering the light-shielding film is embedded on the surface of the mask substrate in which the light-shielding film is embedded. A photomask characterized by being provided with a protective film.
Priority Applications (9)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24665487A JPS6488550A (en) | 1987-09-30 | 1987-09-30 | Photomask |
| CA000578870A CA1315023C (en) | 1987-09-30 | 1988-09-29 | Photo-mask |
| EP88309089A EP0310412B1 (en) | 1987-09-30 | 1988-09-30 | Improvements in photo-masks |
| DE3889053T DE3889053T2 (en) | 1987-09-30 | 1988-09-30 | Photomasks. |
| DE3856089T DE3856089T2 (en) | 1987-09-30 | 1988-09-30 | Photomasks |
| EP93202205A EP0574092B1 (en) | 1987-09-30 | 1988-09-30 | Photo-masks |
| US07/631,277 US5260150A (en) | 1987-09-30 | 1990-12-20 | Photo-mask with light shielding film buried in substrate |
| CA000616373A CA1322685C (en) | 1987-09-30 | 1992-05-07 | Photo-mask |
| US08/102,229 US5403683A (en) | 1987-09-30 | 1993-08-05 | Photo-mask |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24665487A JPS6488550A (en) | 1987-09-30 | 1987-09-30 | Photomask |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6488550A JPS6488550A (en) | 1989-04-03 |
| JPH0544016B2 true JPH0544016B2 (en) | 1993-07-05 |
Family
ID=17151633
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP24665487A Granted JPS6488550A (en) | 1987-09-30 | 1987-09-30 | Photomask |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6488550A (en) |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2589276Y2 (en) * | 1990-03-07 | 1999-01-27 | 株式会社きもと | Surface protection film |
| JP2000206671A (en) | 1999-01-13 | 2000-07-28 | Mitsubishi Electric Corp | Photomask, its production and production of semiconductor integrated circuit device |
| JP3760086B2 (en) * | 2000-07-07 | 2006-03-29 | 株式会社ルネサステクノロジ | Photomask manufacturing method |
| CN1846174A (en) * | 2003-08-25 | 2006-10-11 | 凸版光掩膜公司 | Photomask and method for maintaining optical properties of the same |
| JP5064041B2 (en) * | 2007-01-18 | 2012-10-31 | 株式会社エスケーエレクトロニクス | Photomask having protective film formed on its surface and method for manufacturing the same |
| JP2008310092A (en) * | 2007-06-15 | 2008-12-25 | Shin Etsu Chem Co Ltd | Photomask |
| JP2016018187A (en) * | 2014-07-11 | 2016-02-01 | 株式会社ディスコ | Method for producing exposure mask |
| JP2016028442A (en) * | 2015-10-08 | 2016-02-25 | 大日本印刷株式会社 | Template |
| JP6308281B2 (en) * | 2016-10-21 | 2018-04-11 | 大日本印刷株式会社 | Template manufacturing method |
| CN109265013A (en) * | 2018-10-16 | 2019-01-25 | 彩虹（合肥）液晶玻璃有限公司 | Etaching device and cleaning equipment |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5023595A (en) * | 1973-06-29 | 1975-03-13 |
-
1987
- 1987-09-30 JP JP24665487A patent/JPS6488550A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5023595A (en) * | 1973-06-29 | 1975-03-13 |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6488550A (en) | 1989-04-03 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP4764214B2 (en) | Halftone phase shift mask and manufacturing method thereof | |
| JPH0544016B2 (en) | ||
| JPH0427614B2 (en) | ||
| CN115280236A (en) | Mask blank, transfer mask, and method for manufacturing semiconductor device | |
| US5403683A (en) | Photo-mask | |
| CA2221723C (en) | Optical card | |
| JPH0547040A (en) | Optical recording medium | |
| JP3009723B2 (en) | Method of manufacturing optically readable disk and the disk | |
| US4547876A (en) | Optical recording medium and information record and method of making same | |
| EP0310412B1 (en) | Improvements in photo-masks | |
| JPH0570213B2 (en) | ||
| JPH02179941A (en) | Optical information recording medium and its production | |
| JPS6161375B2 (en) | ||
| JPS6034171B2 (en) | Video disk master using optical recording method | |
| JP5339085B2 (en) | Reflective mask, manufacturing method thereof, and mask pattern inspection method | |
| JPS60164937A (en) | Information recording medium | |
| JPH0339341B2 (en) | ||
| JPH0359493B2 (en) | ||
| US20030193101A1 (en) | Super resolution optical disk mother mold | |
| GB2110115A (en) | Optical recording medium | |
| JPH0648548B2 (en) | Method of manufacturing optical memory device | |
| JP3139479B2 (en) | Information recording medium, method for manufacturing information recording medium, method for recording / reproducing information, and method for erasing information | |
| JPH04324445A (en) | Mask for exposing and production thereof | |
| JPS6223861B2 (en) | ||
| JPS62123465A (en) | Photomask |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20070705 Year of fee payment: 14 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20080705 Year of fee payment: 15 |
|
| EXPY | Cancellation because of completion of term | ||
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20080705 Year of fee payment: 15 |