JP2007249198A

JP2007249198A - Manufacturing method for four-gradation photomask, and photomask blank

Info

Publication number: JP2007249198A
Application number: JP2007037634A
Authority: JP
Inventors: Michiaki Sano; 道明佐野
Original assignee: Hoya Corp
Current assignee: Hoya Corp
Priority date: 2006-02-20
Filing date: 2007-02-19
Publication date: 2007-09-27
Anticipated expiration: 2027-02-19
Also published as: JP4570632B2

Abstract

PROBLEM TO BE SOLVED: To manufacture a four-gradation photomask with a small number of times of drawing through a photolithography stage. SOLUTION: The manufacturing method includes the stages of: preparing a photomask blank which has a first translucent film and a light shield film formed of materials mutually resistive to etching thereof on a light-transmissive substrate; forming a first resist pattern on the light shield film; etching the light shield film using the first resist pattern as a mask, and then etching the translucent film and further peeling the first resist pattern; forming a second translucent film on the light-transmissive substrate and light shield film; forming a second resist pattern on the second translucent film; and etching the second translucent film and light shield film using the second resist pattern as a mask and then removing the second resist pattern. COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、液晶表示装置（ＬｉｑｕｉｄＣｒｙｓｔａｌＤｉｓｐｌａｙ：以下、ＬＣＤと称する）の薄膜トランジスタ（ＴｈｉｎＦｉｌｍＴｒａｎｓｉｓｔｏｒ：以下、ＴＦＴと称する）などの製造に好適に使用される４階調フォトマスクの製造方法、及びこの４階調フォトマスクの製造方法に用いられるフォトマスクブランクに関する。 The present invention relates to a method of manufacturing a four-tone photomask suitably used for manufacturing a thin film transistor (hereinafter referred to as TFT) of a liquid crystal display (Liquid Crystal Display: hereinafter referred to as LCD) and the like, and The present invention relates to a photomask blank used in the manufacturing method of this four-tone photomask.

光透過率が３段階以上の多段階に変化する多階調フォトマスクが、特許文献１に開示されている。この多階調フォトマスクは、光学素子の屈折面や反射面を創成する際に使用される。 A multi-tone photomask whose light transmittance changes in multiple stages of three or more stages is disclosed in Patent Document 1. This multi-tone photomask is used when creating a refracting surface or a reflecting surface of an optical element.

上記公報記載の多階調フォトマスクは、まず、透光性基板上に形成された金属化合物等の膜上にレジスト膜を形成し、このレジスト膜を露光して描画し、現像して第１レジストパターンを形成する。そして、この第１レジストパターンをマスクにして上記金属化合物等の膜をエッチングする。 In the multi-tone photomask described in the above publication, first, a resist film is formed on a film of a metal compound or the like formed on a light-transmitting substrate, the resist film is exposed, drawn, developed, and developed. A resist pattern is formed. Then, the film of the metal compound or the like is etched using the first resist pattern as a mask.

次に、上記金属化合物等の膜上に再度レジスト膜を形成し、このレジスト膜を露光・描画して現像し、第２レジストパターンを形成する。そして、この第２レジストパターンをマスクにして上記金属化合物等の膜を再度エッチングする。上述のレジストパターンの形成と金属化合物等の膜のエッチングとを所望回数繰り返すことで、多階調のフォトマスクを製造している。
特開平９−１４６２５９号公報 Next, a resist film is formed again on the metal compound film, and the resist film is exposed, drawn and developed to form a second resist pattern. Then, using the second resist pattern as a mask, the metal compound film or the like is etched again. A multi-tone photomask is manufactured by repeating the above-described resist pattern formation and etching of a film of a metal compound or the like a desired number of times.
JP 9-146259 A

ところが、上記公報記載の多階調フォトマスクの製造方法では、金属化合物等の膜をエッチングする回数と、そのエッチング加工用のレジストパターンを形成するための露光・描画回数とが同一回数であるため、露光・描画回数が増大してしまう。例えば、光透過率を４段階に変化させる４階調のフォトマスクを製造するためには、露光・描画回数を３回実施しなければならない。 However, in the multi-tone photomask manufacturing method described in the above publication, the number of times of etching a film such as a metal compound is the same as the number of times of exposure / drawing for forming a resist pattern for the etching process. The number of exposure / drawing increases. For example, in order to manufacture a four-gradation photomask that changes the light transmittance in four steps, the number of exposures / drawings must be performed three times.

本発明の目的は、上述の事情を考慮してなされたものであり、４階調のフォトマスクをフォトグラフィ工程により少ない描画回数で製造できる４階調のフォトマスクの製造方法、及びこの製造方法に用いられるフォトマスクブランクを提供することにある。 An object of the present invention has been made in consideration of the above-described circumstances, and a manufacturing method of a four-tone photomask capable of manufacturing a four-tone photomask with a small number of drawing operations by a photolithography process, and the manufacturing method. It is to provide a photomask blank used in the manufacturing process.

本発明の第１の態様は、
遮光部、透光部、及びそれぞれ異なる光透過率の第１半透光部と第２半透光部を有する４階調フォトマスクの製造方法において、
透光性基板上に、互いのエッチングに対して耐性を有する材料からなる第１半透光膜と遮光膜とが順次成膜されたフォトマスクブランクを準備する工程と、
このフォトマスクブランクの上記遮光膜上に、前記透光部及び前記第２半透光部を開口領域とした第１レジストパターンを形成する工程と、
上記第１レジストパターンをマスクに上記遮光膜をエッチングした後、上記第１半透光膜をエッチングし、更に上記第１レジストパターンを剥離する工程と、
次に、上記透光性基板及び上記遮光膜上に第２半透光膜を成膜する工程と、
当該第２半透光膜上に、前記透光部及び前記第１半透光部を開口領域とした第２レジス
トパターンを形成する工程と、
上記第２レジストパターンをマスクに上記第２半透光膜及び上記遮光膜をエッチングした後、上記第２レジストパターンを除去して、前記透光部、前記遮光部、前記第１半透光部及び前記第２半透光部を形成する工程と、
を有する４階調フォトマスクの製造方法である。 The first aspect of the present invention is:
In a method for manufacturing a four-tone photomask having a light-shielding portion, a light-transmitting portion, and a first semi-transmissive portion and a second semi-transmissive portion having different light transmittances, respectively.
Preparing a photomask blank in which a first semi-transparent film and a light-shielding film made of materials having resistance to mutual etching are sequentially formed on a translucent substrate;
Forming a first resist pattern having the light-transmitting portion and the second semi-light-transmitting portion as an opening region on the light-shielding film of the photomask blank;
Etching the light-shielding film using the first resist pattern as a mask, etching the first semi-transparent film, and further peeling the first resist pattern;
Next, forming a second semi-transparent film on the translucent substrate and the light shielding film,
Forming a second resist pattern having the light-transmitting portion and the first semi-light-transmitting portion as an opening region on the second semi-transmissive film;
The second semi-transparent film and the light-shielding film are etched using the second resist pattern as a mask, and then the second resist pattern is removed, so that the light-transmitting part, the light-shielding part, and the first semi-transparent part And forming the second semi-transparent part,
Is a method of manufacturing a four-tone photomask having

本発明の第２の態様は、
遮光部、透光部、及びそれぞれ異なる光透過率の第１半透光部と第２半透光部を有する４階調フォトマスクの製造方法において、
透光性基板上に、互いのエッチングに対して耐性を有する材料からなる第１半透光膜と遮光膜とが順次成膜されたフォトマスクブランクを準備する工程と、
このフォトマスクブランクの上記遮光膜上に、前記透光部及び前記第２半透光部を開口領域とした第１レジストパターンを形成する工程と、
上記第１レジストパターンをマスクに上記遮光膜をエッチングした後、上記第１レジストパターンを剥離し、上記遮光膜をマスクに上記第１半透光膜をエッチングする工程と、
次に、上記透光性基板及び上記遮光膜上に第２半透光膜を成膜する工程と、
当該第２半透光膜上に、前記透光部及び前記第１半透光部を開口領域とした第２レジストパターンを形成する工程と、
上記第２レジストパターンをマスクに上記第２半透光膜及び上記遮光膜をエッチングした後、上記第２レジストパターンを除去して、前記透光部、前記遮光部、前記第１半透光部及び前記第２半透光部を形成する工程と、
を有する４階調フォトマスクの製造方法である。 The second aspect of the present invention is:
In a method for manufacturing a four-tone photomask having a light-shielding portion, a light-transmitting portion, and a first semi-transmissive portion and a second semi-transmissive portion having different light transmittances, respectively.
Preparing a photomask blank in which a first semi-transparent film and a light-shielding film made of materials having resistance to mutual etching are sequentially formed on a translucent substrate;
Forming a first resist pattern having the light-transmitting portion and the second semi-light-transmitting portion as an opening region on the light-shielding film of the photomask blank;
Etching the light shielding film using the first resist pattern as a mask, then peeling the first resist pattern and etching the first semi-transparent film using the light shielding film as a mask;
Next, forming a second semi-transparent film on the translucent substrate and the light shielding film,
Forming a second resist pattern having the light-transmitting portion and the first semi-light-transmitting portion as an opening region on the second semi-transmissive film;
The second semi-transparent film and the light-shielding film are etched using the second resist pattern as a mask, and then the second resist pattern is removed, so that the light-transmitting part, the light-shielding part, and the first semi-transparent part And forming the second semi-transparent part,
Is a method of manufacturing a four-tone photomask having

本発明の第３の態様は、
上記第２半透光膜は、上記遮光膜と同様のエッチングが可能な材料からなる本発明の第１又は２の態様に記載の４階調フォトマスクの製造方法である。 The third aspect of the present invention is:
The second semi-transparent film is the four-tone photomask manufacturing method according to the first or second aspect of the present invention, which is made of a material that can be etched in the same manner as the light-shielding film.

本発明の第４の態様は、
上記第１半透光膜が、モリブデンシリサイドを主成分とした材料からなり、上記遮光膜及び上記第２半透光膜がクロムを主成分とした材料からなる本発明の第１〜３の態様のいずれかに記載の４階調フォトマスクの製造方法である。 The fourth aspect of the present invention is:
The first to third aspects of the present invention, wherein the first semi-transparent film is made of a material containing molybdenum silicide as a main component, and the light shielding film and the second semi-transparent film are made of a material containing chromium as a main component. The method for producing a four-tone photomask according to any one of the above.

本発明の第５の態様は、
本発明の第１〜４の態様のいずれかに記載の４階調フォトマスクの製造方法に用いるためのフォトマスクブランクであって、
透光性基板と、前記透光性基板上に第１半透光膜と遮光膜とが積層されたパターンと、前記透光性基板上及び当該パターン上に成膜された第２半透光膜と、を有するフォトマスクブランクである。 According to a fifth aspect of the present invention,
A photomask blank for use in the method for producing a four-tone photomask according to any one of the first to fourth aspects of the present invention,
A translucent substrate, a pattern in which a first semi-transparent film and a light-shielding film are stacked on the translucent substrate, and a second semi-transparent film formed on the translucent substrate and the pattern. A photomask blank having a film.

本発明の第６の態様は、
遮光部、透光部、及びそれぞれ異なる光透過率の第１半透光部と第２半透光部を有する４階調フォトマスクの製造方法において、
透光性基板上に、第１半透光膜、第２半透光膜及び遮光膜が順次成膜され、これらの第１半透光膜及び遮光膜と上記第２半透光膜とが互いのエッチングに対して耐性を有する材料からなるフォトマスクブランクを準備する工程と、
このフォトマスクブランクの上記遮光膜上に、前記透光部及び前記第１半透光部を開口領域とした第１レジストパターンを形成する工程と、
上記第１レジストパターンをマスクに上記遮光膜をエッチングした後、上記第２半透光膜をエッチングし、更に上記第１レジストパターンを剥離する工程と、
次に、前記透光部及び前記第２半透光部を開口領域とした第２レジストパターンを形成
する工程と、
上記第２レジストパターンをマスクに上記遮光膜及び上記第１半透光膜をエッチングした後、上記第２レジストパターンを除去して、前記透光部、前記遮光部、前記第１半透光部及び前記第２半透光部を形成する工程と、
を有する４階調フォトマスクの製造方法である。 The sixth aspect of the present invention is:
In a method for manufacturing a four-tone photomask having a light-shielding portion, a light-transmitting portion, and a first semi-transmissive portion and a second semi-transmissive portion having different light transmittances, respectively.
A first semi-transparent film, a second semi-transparent film, and a light-shielding film are sequentially formed on the translucent substrate, and the first semi-transparent film, the light-shielding film, and the second semi-transparent film are formed. Preparing a photomask blank made of a material resistant to mutual etching;
Forming a first resist pattern having the light-transmitting portion and the first semi-light-transmitting portion as an opening region on the light-shielding film of the photomask blank;
Etching the light-shielding film using the first resist pattern as a mask, etching the second semi-transparent film, and further peeling the first resist pattern;
Next, a step of forming a second resist pattern having the light-transmitting portion and the second semi-light-transmitting portion as opening regions;
After the light shielding film and the first semi-transparent film are etched using the second resist pattern as a mask, the second resist pattern is removed, and the light transmitting part, the light shielding part, and the first semi light transmitting part are removed. And forming the second semi-transparent part,
Is a method of manufacturing a four-tone photomask having

本発明の第７の態様は、
遮光部、透光部、及びそれぞれ異なる光透過率の第１半透光部と第２半透光部を有する４階調フォトマスクの製造方法において、
透光性基板上に、第１半透光膜、第２半透光膜及び遮光膜が順次成膜され、これらの第１半透光膜及び遮光膜と上記第２半透光膜とが互いのエッチングに対して耐性を有する材料からなるフォトマスクブランクを準備する工程と、
このフォトマスクブランクの上記遮光膜上に、前記透光部及び前記第１半透光部を開口領域とした第１レジストパターンを形成する工程と、
上記第１レジストパターンをマスクに上記遮光膜をエッチングした後、上記第１レジストパターンを剥離し、上記遮光膜をマスクに上記第２半透光膜をエッチングする工程と、
次に、前記透光部及び前記第２半透光部を開口領域とした第２レジストパターンを形成する工程と、
上記第２レジストパターンをマスクに上記遮光膜及び上記第１半透光膜をエッチングした後、上記第２レジストパターンを除去して、前記透光部、前記遮光部、前記第１半透光部及び前記第２半透光部を形成する工程と、
を有する４階調フォトマスクの製造方法である。 The seventh aspect of the present invention is
In a method for manufacturing a four-tone photomask having a light-shielding portion, a light-transmitting portion, and a first semi-transmissive portion and a second semi-transmissive portion having different light transmittances, respectively.
A first semi-transparent film, a second semi-transparent film, and a light-shielding film are sequentially formed on the translucent substrate, and the first semi-transparent film, the light-shielding film, and the second semi-transparent film are formed. Preparing a photomask blank made of a material resistant to mutual etching;
Forming a first resist pattern having the light-transmitting portion and the first semi-light-transmitting portion as an opening region on the light-shielding film of the photomask blank;
Etching the light shielding film using the first resist pattern as a mask, then peeling the first resist pattern and etching the second semi-transparent film using the light shielding film as a mask;
Next, a step of forming a second resist pattern having the light-transmitting portion and the second semi-light-transmitting portion as opening regions;
After the light shielding film and the first semi-transparent film are etched using the second resist pattern as a mask, the second resist pattern is removed, and the light transmitting part, the light shielding part, and the first semi light transmitting part are removed. And forming the second semi-transparent part,
Is a method of manufacturing a four-tone photomask having

本発明の第８の態様は、
上記第１半透光膜と上記遮光膜とが同様のエッチング剤によってエッチングが可能である本発明の第６又は７の態様に記載の４階調フォトマスクの製造方法である。 The eighth aspect of the present invention is
The four-tone photomask manufacturing method according to the sixth or seventh aspect of the present invention, wherein the first semi-transparent film and the light-shielding film can be etched with the same etching agent.

本発明の第９の態様は、
上記第２半透光膜が、モリブデンシリサイドを主成分とした材料からなり、上記第１半透光膜及び上記遮光膜がクロムを主成分とした材料からなる本発明の第８の態様に記載の４階調フォトマスクの製造方法である。 The ninth aspect of the present invention provides
In the eighth aspect of the present invention, the second semi-transparent film is made of a material mainly composed of molybdenum silicide, and the first semi-transparent film and the light-shielding film are made of a material mainly composed of chromium. The four-tone photomask manufacturing method.

本発明の第１０の態様は、
本発明の第６〜９の態様のいずれかに記載の４階調フォトマスクの製造方法に用いるためのフォトマスクブランクであって、
透光性基板と、前記透光性基板上に順次積層された第１半透光膜、第２半透光膜及び遮光膜と、を有するフォトマスクブランクである。 The tenth aspect of the present invention provides
A photomask blank for use in the method for producing a four-tone photomask according to any one of the sixth to ninth aspects of the present invention,
A photomask blank comprising a translucent substrate, and a first semi-transparent film, a second semi-transparent film, and a light-shielding film sequentially stacked on the translucent substrate.

請求項1乃至５のいずれかに記載の発明によれば、透光性基板上に、互いのエッチング
に対し耐性を有する材料からなる第１半透光膜と遮光膜とが順次成膜され、この遮光膜上に、好ましくは遮光膜と同様のエッチングが可能な材料からなる第２半透光膜が成膜されることから、互いにエッチング耐性がある膜とない膜との組合せにより、フォトリソグラフィ工程によって描画回数を低減して４階調フォトマスクを製造できる。 According to the invention according to any one of claims 1 to 5, the first semi-transparent film and the light-shielding film made of materials having resistance to mutual etching are sequentially formed on the translucent substrate, On this light shielding film, a second semi-transparent film made of a material that can be etched, preferably the same as the light shielding film, is formed. A four-tone photomask can be manufactured by reducing the number of times of writing by a process.

請求項６乃至１０のいずれかに記載の発明によれば、透光性基板上に、第１半透光膜
、第２半透光膜及び遮光膜が順次成膜され、第１半透光膜と遮光膜とが同様のエッチングが可能であり、これらの第１半透光膜及び遮光膜と第２半透光膜とが互いのエッチングに対して耐性を有する材料からなることから、互いにエッチング耐性がある膜とない膜との組合せにより、フォトリソグラフィ工程によって描画回数を低減して４階調フォトマスク
を製造できる。 According to the invention of any one of claims 6 to 10, the first semi-transparent film, the second semi-transparent film, and the light-shielding film are sequentially formed on the translucent substrate, and the first semi-transparent film is formed. Since the film and the light-shielding film can be etched in the same manner, the first semi-transparent film and the light-shielding film and the second semi-transparent film are made of materials having resistance to mutual etching. A combination of a film having etching resistance and a film having no etching resistance can reduce the number of times of drawing by a photolithography process and manufacture a four-tone photomask.

以下、本発明を実施するための最良の形態を、図面に基づき説明する。
［Ａ］第１の実施の形態（図１、図２）
図１は、本発明に係る４階調フォトマスクの製造方法における第１の実施の形態である４階調グレートーンマスクの製造工程を示す工程図である。図２は、図１の製造工程により製造された４階調グレートーンマスクを示し、（Ａ）が平面図、（Ｂ）が側断面図である。 The best mode for carrying out the present invention will be described below with reference to the drawings.
[A] First embodiment (FIGS. 1 and 2)
FIG. 1 is a process diagram showing a manufacturing process of a four-tone gray-tone mask according to the first embodiment of the method for manufacturing a four-tone photomask according to the present invention. 2A and 2B show a four-tone gray-tone mask manufactured by the manufacturing process of FIG. 1, wherein FIG. 2A is a plan view and FIG. 2B is a side sectional view.

図２に示すグレートーンマスク１０は、例えば液晶表示装置（ＬＣＤ）の薄膜トランジスタ（ＴＦＴ）やカラーフィルタ、またはプラズマディスプレイパネル（ＰＤＰ）などを製造するために用いられるものであり、被転写体１１上に、膜厚が段階的または連続的に異なるレジストパターン１２を形成するものである。尚、図２（Ｂ）中において符号１９Ａ、１９Ｂ、１９Ｃは、被転写体１１において積層された膜を示す。 A gray tone mask 10 shown in FIG. 2 is used for manufacturing, for example, a thin film transistor (TFT), a color filter, a plasma display panel (PDP), or the like of a liquid crystal display (LCD). In addition, the resist patterns 12 having different film thicknesses are formed stepwise or continuously. In FIG. 2B, reference numerals 19A, 19B, and 19C denote films stacked on the transfer object 11.

上記グレートーンマスク１０は、当該グレートーンマスク１０の使用時に露光光を遮光（光透過率が略０％）させる遮光部１３と、露光光を略１００％透過させる透光部１４と、露光光の透過率を２０〜５０％程度に低減させる第１半透光部１５Ａ及び第２半透光部１５Ｂとを有して構成される。このように、遮光部１３及び透光部１４の他に半透光部を有するフォトマスクがグレートーンマスクと称される。上記第１半透光部１５Ａと第２半透光部１５Ｂとは光透過率が異なり、本実施の形態では、第１半透光部１５Ａの光透過率が第２半透光部１５Ｂの光透過率よりも低く設定されている。従って、上記グレートーンマスク１０は、露光光の透過率が４段階に異なる４階調のグレートーンマスクとなっている。 The gray tone mask 10 includes a light shielding portion 13 that shields exposure light (light transmittance is approximately 0%) when the gray tone mask 10 is used, a light transmitting portion 14 that transmits approximately 100% of the exposure light, and exposure light. The first semi-transmissive portion 15A and the second semi-transmissive portion 15B are configured to reduce the transmittance of the light to about 20 to 50%. In this way, a photomask having a semi-transparent part in addition to the light-shielding part 13 and the translucent part 14 is referred to as a gray tone mask. The first semi-transmissive portion 15A and the second semi-transmissive portion 15B have different light transmittances. In this embodiment, the light transmittance of the first semi-transmissive portion 15A is that of the second semi-transmissive portion 15B. It is set lower than the light transmittance. Therefore, the gray tone mask 10 is a four-tone gray tone mask having different exposure light transmittances in four stages.

上記第１半透光部１５Ａは、ガラス基板等の透光性基板１６の表面に光半透過性の第１半透光膜１７Ａが設けられて構成される。また、第２半透光部１５Ｂは、透光性基板１６の表面に光半透過性の第２半透光膜１７Ｂが設けられて構成される。更に、遮光部１３は、透光性基板１６の表面に、上記第１半透光膜１７Ａ、遮光膜１８及び上記第２半透光膜１７Ｂが順次積層されて構成される。 The first semi-transparent portion 15A is configured by providing a light semi-transmissive first semi-transparent film 17A on the surface of a translucent substrate 16 such as a glass substrate. The second semi-transparent portion 15B is configured by providing a light semi-transmissive second semi-transparent film 17B on the surface of the translucent substrate 16. Further, the light shielding portion 13 is configured by sequentially laminating the first semi-transmissive film 17A, the light-shielding film 18 and the second semi-transmissive film 17B on the surface of the translucent substrate 16.

上記第１半透光膜１７Ａは、金属とシリコンを含む薄膜であり、モリブデンシリサイド（ＭｏＳｉ）を主成分とする膜が好ましく、例えばＭｏＳｉ（ＭｏＳｉ２）、ＭｏＳｉＮ、ＭｏＳｉＯＮ、ＭｏＳｉＣＯＮ等が挙げられる。また、第２半透光膜１７Ｂ及び遮光膜１８は、クロムを主成分とする膜であり、遮光膜１８はクロム、第２半透光膜１７Ｂは窒化クロム、酸化クロム、酸窒化クロム、フッ化クロム等が好ましい。第１半透光部１５Ａの光透過率は、第１半透光膜１７Ａの膜材質と膜厚との選定によって設定される。また、第２半透光部１５Ｂの光透過率は、第２半透光膜１７Ｂの膜材質と膜厚との選定によって設定される。更に、遮光部１３の光透過率は、第１半透光膜１７Ａ、第２半透光膜１７Ｂ及び遮光膜１８の膜材質と膜厚との選定によって設定される。 The first semi-transparent film 17A is a thin film containing metal and silicon and is preferably a film mainly composed of molybdenum silicide (MoSi). Examples thereof include MoSi (MoSi 2), MoSiN, MoSiON, and MoSiCON. The second semi-transparent film 17B and the light shielding film 18 are films mainly composed of chromium. The light shielding film 18 is chromium, and the second semi-transparent film 17B is chromium nitride, chromium oxide, chromium oxynitride, fluorine. Chromium oxide is preferred. The light transmittance of the first semi-transparent portion 15A is set by selecting the film material and film thickness of the first semi-transparent film 17A. Further, the light transmittance of the second semi-transparent portion 15B is set by selecting the film material and film thickness of the second semi-transparent film 17B. Further, the light transmittance of the light shielding portion 13 is set by selecting the film materials and film thicknesses of the first semi-transmissive film 17A, the second semi-transmissive film 17B, and the light-shielding film 18.

上述のような４階調のグレートーンマスク１０を使用したとき、遮光部１３では露光光が透過せず、第２半透光部１５Ｂでは露光光が低減され、第１半透光部１５Ａでは、第２半透光部１５Ｂよりも露光光が更に低減されるため、被転写体１１上に付着したレジスト膜（ポジ型フォトレジスト膜）は、遮光部１３に対応する部分で膜厚が最も高くなり、第１半透光部１５Ａに対応する部分で膜厚が次に厚くなり、第２半透光部１５Ｂに対応する部分で膜厚が薄くなり、透光部１４に対応する部分で膜がないレジストパターン１２を形成する。なお、レジスト膜をネガ型フォトレジスト膜とした場合には、各部に対応するレジスト膜の膜厚は上記の逆になる。 When the four-tone gray-tone mask 10 as described above is used, the exposure light is not transmitted through the light shielding portion 13, the exposure light is reduced at the second semi-transparent portion 15B, and the first semi-transparent portion 15A. Since the exposure light is further reduced as compared with the second semi-transparent portion 15B, the resist film (positive photoresist film) adhering to the transferred body 11 has the largest thickness at the portion corresponding to the light shielding portion 13. The film thickness becomes higher next in the portion corresponding to the first semi-transparent portion 15A, the film thickness becomes thinner in the portion corresponding to the second semi-transparent portion 15B, and in the portion corresponding to the translucent portion 14. A resist pattern 12 having no film is formed. If the resist film is a negative photoresist film, the resist film thickness corresponding to each part is the reverse of the above.

そして、レジストパターン１２の膜のない部分（透光部１４に対応する部分）で、被転写体１１における例えば膜１９Ａ、１９Ｂ及び１９Ｃに第１エッチングを実施する。続いて、レジストパターン１２の膜のうち最も膜厚が薄い部分（第２半透光部１５Ｂに対応する部分）をアッシング等によって除去し、この部分（第２半透光部１５Ｂに対応する部分）で、被転写体１１における例えば膜１９Ｂ及び１９Ｃに第２エッチングを実施する。続いて、レジストパターン１２の膜のうち次に膜厚が薄い部分（第１半透光部１５Ａに対応する部分）をアッシング等によって除去し、この部分（第１半透光部１５Ａに対応する部分）で、被転写体１１における例えば膜１９Ｃに第３エッチングを実施する。このようにして、１枚のグレートーンマスク１０を用いて、従来のフォトマスク３枚分の工程が実施されることになり、マスク枚数が削減される。 Then, first etching is performed on, for example, the films 19 A, 19 B, and 19 C in the transferred object 11 at a portion of the resist pattern 12 where there is no film (a portion corresponding to the light transmitting portion 14). Subsequently, the thinnest portion (the portion corresponding to the second semi-transparent portion 15B) of the film of the resist pattern 12 is removed by ashing or the like, and this portion (the portion corresponding to the second semi-transparent portion 15B). Then, the second etching is performed on, for example, the films 19B and 19C in the transferred object 11. Subsequently, the next thinnest part (the part corresponding to the first semi-transparent part 15A) of the film of the resist pattern 12 is removed by ashing or the like, and this part (corresponding to the first semi-transparent part 15A). For example, the third etching is performed on the film 19 C of the transfer target 11. In this manner, the process for three conventional photomasks is performed using one graytone mask 10, and the number of masks is reduced.

ところで、上述のような４階調グレートーンマスク１０を製造する製造工程を、図１を用いて以下に述べる。 A manufacturing process for manufacturing the above-described four-tone gray-tone mask 10 will be described below with reference to FIG.

まず、透光性基板１６の表面に、第１半透光膜１７Ａ、遮光膜１８を順次成膜する工程を実施してフォトマスクブランク２０を形成し、準備する（図１（Ａ））。この第１半透光膜１７Ａと遮光膜１８は、グレートーンマスク１０の製造工程において、互いのエッチングに対し耐性を有する膜になっている。たとえば、第１半透光膜１７Ａは、クロム用エッチングガスまたは液に対して耐性を有し、遮光膜１８は、ＭｏＳｉ用エッチングガスまたは液に対して耐性を有する素材（材料）を選択することが出来る。 First, a photomask blank 20 is formed by preparing a first semi-transparent film 17A and a light-shielding film 18 on the surface of the translucent substrate 16 to prepare (FIG. 1A). The first semi-transmissive film 17A and the light shielding film 18 are films having resistance to mutual etching in the manufacturing process of the gray tone mask 10. For example, the first semi-transparent film 17A is resistant to a chromium etching gas or liquid, and the light shielding film 18 is a material (material) that is resistant to an MoSi etching gas or liquid. I can do it.

次に、上記フォトマスクブランク２０の遮光膜１８上にレジスト膜（ポジ型フォトレジスト膜）を成膜する。続いて、このレジスト膜を電子線またはレーザーを用いた描画装置によって露光して描画し、現像して、第１レジストパターン２１を形成する（図１（Ｂ））。この第１レジストパターン２１は、製造されるグレートーンマスク１０の透光部１４及び第２半透光部１５Ｂを開口領域とする形状に形成される。 Next, a resist film (positive photoresist film) is formed on the light shielding film 18 of the photomask blank 20. Subsequently, the resist film is exposed and drawn by a drawing apparatus using an electron beam or a laser, and developed to form a first resist pattern 21 (FIG. 1B). The first resist pattern 21 is formed in a shape having the light-transmitting portion 14 and the second semi-light-transmitting portion 15B of the manufactured gray-tone mask 10 as opening regions.

次に、この第１レジストパターン２１が形成されたフォトマスクブランク２０の遮光膜１８を、クロム用エッチングガスまたは液を用い、第１レジストパターン２１をマスクにしてドライエッチングまたはウェットエッチングする（図１（Ｃ））。このエッチングにより、遮光膜１８に遮光膜パターン２２が形成される。また、第１半透光膜１７Ａは、クロム用エッチングガスまたは液に対して耐性を有することから、この遮光膜１８のエッチング時にはエッチングされにくい。 Next, the light-shielding film 18 of the photomask blank 20 on which the first resist pattern 21 is formed is dry-etched or wet-etched using a chromium etching gas or liquid with the first resist pattern 21 as a mask (FIG. 1). (C)). By this etching, a light shielding film pattern 22 is formed on the light shielding film 18. Further, since the first semi-transparent film 17A is resistant to the etching gas or liquid for chromium, it is difficult to etch when the light shielding film 18 is etched.

遮光膜パターン２２の形成後、第１レジストパターン２１を剥離し（図１（Ｄ））、その後、遮光膜パターン２２をマスクにし、第１半透光膜１７Ａをドライまたはウェットエッチングして第１半透光膜パターン２３を形成する（図１（Ｅ））。または、上記遮光膜パターン２２の形成後、第１レジストパターン２１及び遮光膜パターン２２をマスクにし、第１半透光膜１７Ａをドライまたはウェットエッチングして第１半透光膜パターン２３を形成し、その後に上記第１レジストパターン２１を剥離してもよい。これらのウェットまたはドライエッチングにおいて、遮光膜１８は、ＭｏＳｉ用エッチングガスまたは液に対して耐性を有するため、この第１半透光膜１７Ａのエッチング時にエッチングされることがない。また、上記ＭｏＳｉ用エッチング液としては、例えば弗化水素酸、珪弗化水素酸、弗化水素アンモニウムから選ばれる少なくとも一つの弗素化合物と、過酸化水素、硝酸、硫酸から選ばれる少なくとも一つの酸化剤を含むものが使用される。 After the formation of the light shielding film pattern 22, the first resist pattern 21 is peeled off (FIG. 1D), and then the first semi-transparent film 17A is dry or wet etched using the light shielding film pattern 22 as a mask. A semi-transparent film pattern 23 is formed (FIG. 1E). Alternatively, after the light shielding film pattern 22 is formed, the first semi-transparent film pattern 23 is formed by dry or wet etching the first semi-transparent film 17A using the first resist pattern 21 and the light shielding film pattern 22 as a mask. Thereafter, the first resist pattern 21 may be peeled off. In these wet or dry etching, since the light shielding film 18 is resistant to the etching gas or liquid for MoSi, it is not etched during the etching of the first semi-transparent film 17A. The MoSi etching solution includes, for example, at least one fluorine compound selected from hydrofluoric acid, silicohydrofluoric acid, and ammonium hydrogen fluoride, and at least one oxidation selected from hydrogen peroxide, nitric acid, and sulfuric acid. The one containing the agent is used.

上述のようにして第１半透光膜パターン２３を形成後、遮光膜１８上及び露出した透光性基板１６上に第２半透光膜１７Ｂを成膜して、他のフォトマスクブランク２４、すなわち、透光性基板１６と、この透光性基板１６上に第１半透光膜１７Ａと遮光膜１８とが積
層されたパターンと、露出した透光性基板１６上及び当該パターン上に成膜された第２半透光膜１７Ｂと、を有するフォトブランクマスク２４を形成する（図１（Ｆ））。なお、第２半透光膜１７Ｂと遮光膜１８とは、グレートーンマスク１０の製造工程において、互いのエッチングに対して耐性が小さい膜である。すなわち、第２半透光膜１７Ｂと遮光膜１８とは、同種のエッチングガスまたは液によってエッチングが可能な素材（材料）により構成される。 After forming the first semi-transparent film pattern 23 as described above, a second semi-transparent film 17B is formed on the light shielding film 18 and the exposed translucent substrate 16, and another photomask blank 24 is formed. That is, the translucent substrate 16, the pattern in which the first semi-transparent film 17A and the light-shielding film 18 are laminated on the translucent substrate 16, the exposed translucent substrate 16 and the pattern. A photo blank mask 24 having the formed second semi-transmissive film 17B is formed (FIG. 1F). Note that the second semi-transparent film 17B and the light shielding film 18 are films having low resistance to mutual etching in the manufacturing process of the gray tone mask 10. That is, the second semi-transparent film 17B and the light shielding film 18 are made of a material (material) that can be etched with the same kind of etching gas or liquid.

次に、上記フォトマスクブランク２４の第２半透光膜１７Ｂ上にレジスト膜を成膜する。続いて、このレジスト膜を前述と同様に露光して描画し、現像して、第２レジストパターン２５を形成する（図１（Ｇ））。この第２レジストパターン２５は、透光部１４及び第１半透光部１５Ａを開口領域とする形状に形成される。 Next, a resist film is formed on the second semi-transparent film 17B of the photomask blank 24. Subsequently, the resist film is exposed, drawn and developed in the same manner as described above to form a second resist pattern 25 (FIG. 1G). The second resist pattern 25 is formed in a shape having the light transmitting portion 14 and the first semi-light transmitting portion 15A as an opening region.

次に、第２レジストパターン２５をマスクにして、前記クロム用エッチングガスまたは液を用い遮光膜１８及び第２半透光膜１７Ｂをドライまたはウェットエッチングする（図１（Ｈ））。その後、残存する第２レジストパターン２５を除去（剥離）して、第１半透光膜１７Ａからなる第１半透光部１５Ａ、第２半透光膜１７Ｂからなる第２半透光部１５Ｂ、第１半透光膜１７Ａ、第２半透光膜１７Ｂ及び遮光膜１８が積層されてなる遮光部１３を有する４階調のグレートーンマスク１０を製造する（図１（Ｉ））。 Next, using the second resist pattern 25 as a mask, the light shielding film 18 and the second semi-transparent film 17B are dry or wet etched using the chromium etching gas or liquid (FIG. 1H). Thereafter, the remaining second resist pattern 25 is removed (peeled), and the first semi-transmissive portion 15A made of the first semi-transmissive film 17A and the second semi-transmissive portion 15B made of the second semi-transmissive film 17B. Then, the four-tone gray-tone mask 10 having the light-shielding portion 13 formed by laminating the first semi-transparent film 17A, the second semi-transparent film 17B, and the light-shielding film 18 is manufactured (FIG. 1I).

以上のように構成されたことから、上記実施の形態によれば、次の効果を奏する。グレートーンマスク１０の製造工程によれば、透光性基板１６と、この透光性基板１６上に第１半透光膜１７Ａと遮光膜１８とが積層されたパターンと、この透光性基板１６の露出面及び当該パターン上に成膜された第２半透光膜１７Ｂと、を有するフォトブランクマスク２４が形成される。そして、第１半透光膜１７Ａと遮光膜１８とは互いのエッチングに対し耐性を有する膜であり、また、遮光膜１８と第２半透光膜１７Ｂとは同様のエッチング剤によってエッチングが可能な膜である。このように、互いにエッチング耐性が大きい膜と相対的に小さい膜との組合せにより、フォトリソグラフィ工程による描画回数を２回に低減して、４階調のフォトマスク１０を製造できる。 With the configuration as described above, according to the above embodiment, the following effects are obtained. According to the manufacturing process of the gray tone mask 10, the translucent substrate 16, the pattern in which the first semi-transparent film 17A and the light shielding film 18 are laminated on the translucent substrate 16, and the translucent substrate. A photo blank mask 24 having 16 exposed surfaces and a second semi-transparent film 17B formed on the pattern is formed. The first semi-transparent film 17A and the light-shielding film 18 are films resistant to mutual etching, and the light-shielding film 18 and the second semi-transparent film 17B can be etched with the same etching agent. It is a simple film. As described above, the combination of the film having a high etching resistance and the film having a relatively small etching resistance reduces the number of times of drawing in the photolithography process to two, thereby manufacturing the four-tone photomask 10.

［Ｂ］第２の実施の形態（図３、図４）
図３は、本発明に係る４階調フォトマスクの製造方法における第２の実施の形態である４階調グレートーンマスクの製造工程を示す工程図である。図４は、図３の製造工程により製造された４階調グレートーンマスクを示し、（Ａ）が平面図、（Ｂ）が側断面図である。この第２の実施の形態において、前記第１の実施の形態と同様な部分は、同一の符号を付すことにより説明を省略する。 [B] Second embodiment (FIGS. 3 and 4)
FIG. 3 is a process diagram showing a manufacturing process of a 4-tone gray-tone mask which is the second embodiment in the method of manufacturing a 4-tone photomask according to the present invention. 4A and 4B show a four-tone gray-tone mask manufactured by the manufacturing process of FIG. 3, in which FIG. 4A is a plan view and FIG. 4B is a side sectional view. In the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

図２に示すグレートーンマスク３０も、例えば液晶表示装置（ＬＣＤ）の薄膜トランジスタ（ＴＦＴ）やカラーフィルタ、またはプラズマディスプレイパネル（ＰＤＰ）などを製造するために用いられるものであり、被転写体３１上に、膜厚が段階的または連続的に異なるレジストパターン３２を形成するものである。 The gray tone mask 30 shown in FIG. 2 is also used for manufacturing, for example, a thin film transistor (TFT), a color filter, or a plasma display panel (PDP) of a liquid crystal display device (LCD). In addition, resist patterns 32 having different film thicknesses stepwise or continuously are formed.

上記グレートーンマスク３０は、当該グレートーンマスク３０の使用時に露光光を遮光（光透過率が略０％）させる遮光部３３と、露光光を略１００％透過させる透光部３４と、露光光の透過率を２０〜５０％程度に低減させる第１半透光部３５Ａ及び第２半透光部３５Ｂとを有して構成される。上記第１半透光部３５Ａと第２半透光部３５Ｂとは光透過率が異なり、本実施の形態では、第１半透光部３５Ａの光透過率が第２半透光部３５Ｂの光透過率よりも高く設定されている。従って、上記グレートーンマスク３０も、前記グレートーンマスク１０と同様に、露光光の透過率が４段階に異なる４階調のグレートーンマスクとなっている。 The gray-tone mask 30 includes a light-blocking portion 33 that blocks exposure light (light transmittance is approximately 0%) when the gray-tone mask 30 is used, a light-transmitting portion 34 that transmits approximately 100% of the exposure light, and exposure light. The first semi-transmissive portion 35A and the second semi-transmissive portion 35B are configured to reduce the transmittance of the light to about 20 to 50%. The first semi-transmissive part 35A and the second semi-transmissive part 35B have different light transmittances. In the present embodiment, the light transmittance of the first semi-transmissive part 35A is the same as that of the second semi-transmissive part 35B. It is set higher than the light transmittance. Accordingly, the gray tone mask 30 is also a four-tone gray tone mask having different exposure light transmittances in four stages, like the gray tone mask 10.

上記第１半透光部３５Ａは、ガラス基板等の透光性基板１６の表面に光半透過性の第１半透光膜３７Ａが設けられて構成される。また、第２半透光部３５Ｂは、透光性基板１６の表面に、上記第１半透光膜３７Ａと光半透過性の第２半透光膜３７Ｂとが積層されて構成される。更に、遮光部３３は、透光性基板１６の表面に、上記第１半透光膜３７Ａ、第２半透光膜３７Ｂ及び遮光膜３８が順次積層されて構成される。 The first semi-transparent portion 35A is configured by providing a light semi-transmissive first semi-transparent film 37A on the surface of a translucent substrate 16 such as a glass substrate. The second semi-transmissive portion 35B is configured by laminating the first semi-transmissive film 37A and the light semi-transmissive second semi-transmissive film 37B on the surface of the translucent substrate 16. Further, the light shielding portion 33 is configured by sequentially stacking the first semi-transmissive film 37A, the second semi-transmissive film 37B, and the light shielding film 38 on the surface of the translucent substrate 16.

上記第２半透光膜３７Ｂは、金属とシリコンを含む薄膜であり、モリブデンシリサイド（ＭｏＳｉ）を主成分とする膜が好ましく、例えばＭｏＳｉ（ＭｏＳｉ２）、ＭｏＳｉＮ、ＭｏＳｉＯＮ、ＭｏＳｉＣＯＮ等が挙げられる。また、第１半透光膜３７Ａ及び遮光膜３８は、クロムを主成分とする膜であり、遮光膜３８はクロム、第１半透光膜３７Ａは窒化クロム、酸化クロム、酸窒化クロム、フッ化クロム等が好ましい。第１半透光部３５Ａの光透過率は、第１半透光膜３７Ａの膜材質と膜厚との選定によって設定される。また、第２半透光部３５Ｂの光透過率は、第１半透光膜３７Ａ及び第２半透光膜３７Ｂのそれぞれの膜材質と膜厚との選定によって設定される。 The second semi-transparent film 37B is a thin film containing metal and silicon and is preferably a film mainly composed of molybdenum silicide (MoSi). Examples thereof include MoSi (MoSi2), MoSiN, MoSiON, and MoSiCON. The first semi-transparent film 37A and the light-shielding film 38 are films mainly composed of chromium, the light-shielding film 38 is chromium, and the first semi-transparent film 37A is chromium nitride, chromium oxide, chromium oxynitride, fluorine. Chromium oxide is preferred. The light transmittance of the first semi-transparent portion 35A is set by selecting the film material and thickness of the first semi-transparent film 37A. The light transmittance of the second semi-transmissive part 35B is set by selecting the film material and the film thickness of the first semi-transmissive film 37A and the second semi-transmissive film 37B.

上述のような４階調のグレートーンマスク３０を使用したとき、遮光部３３では露光光が透過せず、第１半透光部３５Ａでは露光光が低減され、第２半透光部３５Ｂでは、第１半透光部３５Ａよりも露光光が更に低減されるため、被転写体３１上に付着したレジスト膜（ポジ型フォトレジスト膜）は、遮光部３３に対応する部分で膜厚が最も高くなり、第２半透光部３５Ｂに対応する部分で膜厚が次に厚くなり、第１半透光部３５Ａに対応する部分で膜厚が薄くなり、透光部３４に対応する部分で膜がないレジストパターン３２を形成する。なお、レジスト膜をネガ型フォトレジスト膜とした場合には、各部に対応するレジスト膜の膜厚は上記の逆になる。 When the four-tone gray-tone mask 30 as described above is used, the exposure light is not transmitted through the light shielding portion 33, the exposure light is reduced at the first semi-transmissive portion 35A, and the second semi-transmissive portion 35B. Since the exposure light is further reduced as compared with the first semi-translucent portion 35A, the resist film (positive type photoresist film) adhering to the transfer target 31 has the largest thickness at the portion corresponding to the light shielding portion 33. The film thickness becomes higher next at the portion corresponding to the second semi-transparent portion 35B, the film thickness becomes thinner at the portion corresponding to the first semi-transparent portion 35A, and at the portion corresponding to the translucent portion 34. A resist pattern 32 having no film is formed. If the resist film is a negative photoresist film, the resist film thickness corresponding to each part is the reverse of the above.

そして、レジストパターン３２の膜のない部分（透光部３４に対応する部分）で、被転写体３１における例えば膜１９Ａ、１９Ｂ及び１９Ｃに第１エッチングを実施する。続いて、レジストパターン３２の膜のうち最も膜厚が薄い部分（第１半透光部３５Ａに対応する部分）をアッシング等によって除去し、この部分（第１半透光部３５Ａに対応する部分）で、被転写体３１における例えば膜１９Ｂ及び１９Ｃに第２エッチングを実施する。続いて、レジストパターン３２の膜のうち次に膜厚が薄いが薄い部分（第２半透光部３５Ｂに対応する部分）をアッシング等によって除去し、この部分（第２半透光部３５Ｂに対応する部分）で、被転写体３１における例えば膜１９Ｃに第３エッチングを実施する。このようにして、１枚のグレートーンマスク３０を用いて、従来のフォトマスク３枚分の工程が実施されることになり、マスク枚数が削減される。 Then, first etching is performed on, for example, the films 19 A, 19 B, and 19 C in the transfer target 31 at a portion of the resist pattern 32 where there is no film (a portion corresponding to the light transmitting portion 34). Subsequently, the thinnest portion (portion corresponding to the first semi-translucent portion 35A) of the film of the resist pattern 32 is removed by ashing or the like, and this portion (portion corresponding to the first semi-transparent portion 35A). ), The second etching is performed on, for example, the films 19B and 19C in the transfer target 31. Subsequently, the thinnest part (the part corresponding to the second semi-transparent part 35B) of the film of the resist pattern 32 is removed by ashing or the like, and this part (the second semi-transparent part 35B) is removed. In the corresponding portion), for example, the third etching is performed on the film 19C in the transfer target 31. In this way, the process for three conventional photomasks is performed using one graytone mask 30, and the number of masks is reduced.

ところで、上述のような４階調グレートーンマスク３０を製造する製造工程を、図３を用いて以下に述べる。 A manufacturing process for manufacturing the above-described four-tone gray-tone mask 30 will be described below with reference to FIG.

まず、透光性基板１６の表面に、第１半透光膜３７Ａ、第２半透光膜３７Ｂ及び遮光膜３８を順次成膜する工程を実施してフォトマスクブランク４０を形成し、準備する（図３（Ａ））。ここで、第２半透光膜３７Ｂと遮光膜３８とは、グレートーンマスク３０の製造工程において、互いのエッチングに対し耐性を有する膜になっている。たとえば、第２半透光膜３７Ｂは、クロム用エッチングガスまたは液に対して耐性を有し、遮光膜３８は、ＭｏＳｉ用エッチングカスまたは液に対して耐性を有する素材（材料）を選択することが出来る。また、第１半透光膜３７Ａは、遮光膜３８と同様なエッチングが可能な材料からなり、従って、第１半透光膜３７Ａと遮光膜３８は、互いのエッチングに対し耐性の小さい膜である。すなわち、第１半透光膜３７Ａと遮光膜３８とは、同種のエッチングガスまたは液によってエッチングが可能な素材（材料）により構成される。 First, a step of sequentially forming a first semi-transparent film 37A, a second semi-transparent film 37B, and a light shielding film 38 on the surface of the translucent substrate 16 is performed to form and prepare a photomask blank 40. (FIG. 3 (A)). Here, the second semi-transparent film 37 B and the light shielding film 38 are films having resistance to mutual etching in the manufacturing process of the gray tone mask 30. For example, the second semi-transparent film 37B is resistant to a chromium etching gas or liquid, and the light shielding film 38 is a material (material) that is resistant to MoSi etching residue or liquid. I can do it. The first semi-transparent film 37A is made of a material that can be etched in the same manner as the light-shielding film 38. Therefore, the first semi-transparent film 37A and the light-shielding film 38 are films having low resistance to mutual etching. is there. That is, the first semi-transmissive film 37A and the light shielding film 38 are made of a material that can be etched with the same kind of etching gas or liquid.

次に、上記フォトマスクブランク４０の遮光膜３８上にレジスト膜（ポジ型フォトレジ
スト膜）を成膜する。続いて、このレジスト膜を電子線またはレーザーを用いた描画装置によって露光して描画し、現像して、第１レジストパターン４１を形成する（図３（Ｂ））。この第１レジストパターン４１は、製造されるグレートーンマスク３０の透光部３４及び第１半透光部３５Ａを開口領域とする形状に形成される。 Next, a resist film (positive photoresist film) is formed on the light shielding film 38 of the photomask blank 40. Subsequently, the resist film is exposed and drawn by a drawing apparatus using an electron beam or a laser, and developed to form a first resist pattern 41 (FIG. 3B). The first resist pattern 41 is formed in a shape having the light-transmitting portion 34 and the first semi-light-transmitting portion 35A of the manufactured gray-tone mask 30 as opening regions.

次に、この第１レジストパターン４１が形成されたフォトマスクブランク４０の遮光膜３８を、クロム用エッチングガスまたは液を用い、第１レジストパターン４１をマスクにしてドライエッチングまたはウェットエッチングする（図３（Ｃ））。このエッチングにより、遮光膜３８に遮光膜パターン４２が形成される。また、第２半透光膜３７Ｂは、クロム用エッチングガスまたは液に対して耐性を有することから、この遮光膜３８のエッチング時にはエッチングされにくい。 Next, the light-shielding film 38 of the photomask blank 40 on which the first resist pattern 41 is formed is dry-etched or wet-etched using a chromium etching gas or liquid with the first resist pattern 41 as a mask (FIG. 3). (C)). By this etching, a light shielding film pattern 42 is formed on the light shielding film 38. Further, since the second semi-transparent film 37B is resistant to the etching gas or liquid for chromium, it is difficult to etch when the light shielding film 38 is etched.

遮光膜パターン４２の形成後、第１レジストパターン４１を剥離し、その後、遮光膜パターン４２をマスクにし、第２半透光膜３７Ｂをドライまたはウェットエッチングして第２半透光膜パターン４３を形成する（図３（Ｄ））。または、上記遮光膜パターン４２の形成後、第１レジストパターン４１及び遮光膜パターン４２をマスクにし第２半透光膜３７Ｂをドライまたはウェットエッチングして第２半透光膜パターン４３を形成し、その後に上記第１レジストパターン４１を剥離してもよい。これらのウェットまたはドライエッチングにおいて、遮光膜３８及び第１半透光膜３７Ａは、ＭｏＳｉ用エッチングガスまたは液に対して耐性を有するため、この第２半透光膜３７Ｂのエッチング時にはエッチングされにくい。 After the formation of the light shielding film pattern 42, the first resist pattern 41 is peeled off, and then, using the light shielding film pattern 42 as a mask, the second semi-transmissive film 37B is dry or wet etched to form the second semi-transmissive film pattern 43. It is formed (FIG. 3D). Alternatively, after the formation of the light shielding film pattern 42, the second semitransparent film 37B is dry or wet etched using the first resist pattern 41 and the light shielding film pattern 42 as a mask to form the second semitransparent film pattern 43, Thereafter, the first resist pattern 41 may be peeled off. In these wet or dry etching, the light-shielding film 38 and the first semi-transparent film 37A are resistant to the etching gas or liquid for MoSi, so that they are not easily etched when the second semi-transparent film 37B is etched.

上述のようにして第２半透光膜パターン４３を形成後、遮光膜３８上及び露出した第１半透光膜３７Ａ上にレジスト膜を成膜する。続いて、このレジスト膜を前述と同様に露光して描画し、現像して、第２レジストパターン４４を形成する（図３（Ｅ））。この第２レジストパターン４４は、透光部３４及び第２半透光部３５Ｂを開口領域とする形状に形成される。 After forming the second semi-transparent film pattern 43 as described above, a resist film is formed on the light shielding film 38 and the exposed first semi-transparent film 37A. Subsequently, the resist film is exposed, drawn and developed in the same manner as described above to form a second resist pattern 44 (FIG. 3E). The second resist pattern 44 is formed in a shape having the translucent portion 34 and the second semi-transparent portion 35B as opening regions.

次に、第２レジストパターン４４をマスクにして、前記クロム用エッチングガスまたは液を用い、遮光膜３８及び第１半透光膜３７Ａをドライまたはウェットエッチングする（図３（Ｆ））。その後、残存する第２レジストパターン４４を除去（剥離）して、第１半透光膜３７Ａからなる第１半透光部３５Ａ、第１半透光膜３７Ａ及び第２半透光膜３７Ｂが積層されてなる第２半透光部３５Ｂ、第１半透光膜３７Ａ、第２半透光膜３７Ｂ及び遮光膜３８が積層されてなる遮光部３３を有する４階調のグレートーンマスク３０を製造する（図３（Ｇ））。 Next, using the second resist pattern 44 as a mask, the light shielding film 38 and the first semi-transparent film 37A are dry or wet etched using the chromium etching gas or liquid (FIG. 3F). Thereafter, the remaining second resist pattern 44 is removed (peeled), and the first semi-transmissive portion 35A, the first semi-transmissive film 37A, and the second semi-transmissive film 37B made of the first semi-transmissive film 37A are formed. A four-tone gray-tone mask 30 having a light-shielding portion 33 in which a second semi-transparent portion 35B, a first semi-transparent film 37A, a second semi-transparent film 37B, and a light-shielding film 38 are laminated. Manufacture (FIG. 3G).

以上のように構成されたことから、上記実施の形態によれば、次の効果を奏する。グレートーンマスク３０の製造工程によれば、透光性基板１６と、透光性基板１６上に順次積層された第１半透光膜３７Ａ、第２半透光膜３７Ｂ及び遮光膜３８と、を有するフォトブランクマスク４０が形成される。ここで、第２半透光膜３７Ｂと遮光膜３８とは互いのエッチングに対し耐性を有する膜であり、また、第１半透光膜３７Ａと遮光膜３８とは同様のエッチング剤によってエッチングが可能な膜である。このように、互いにエッチング耐性が大きい膜と相対的に小さい膜との組合せにより、フォトリソグラフィ工程による描画回数を２回に低減して、４階調のフォトマスク１０を製造できる。 With the configuration as described above, according to the above embodiment, the following effects are obtained. According to the manufacturing process of the gray tone mask 30, the translucent substrate 16, the first semi-transparent film 37A, the second semi-transparent film 37B, and the light-shielding film 38 sequentially stacked on the translucent substrate 16, A photo blank mask 40 having the above is formed. Here, the second semi-transparent film 37B and the light-shielding film 38 are films that are resistant to mutual etching, and the first semi-transparent film 37A and the light-shielding film 38 are etched by the same etching agent. It is a possible membrane. As described above, the combination of the film having a high etching resistance and the film having a relatively small etching resistance reduces the number of times of drawing in the photolithography process to two, thereby manufacturing the four-tone photomask 10.

以上、本発明を上記実施の形態に基づいて説明したが、本発明はこれに限定されるものではない。 As mentioned above, although this invention was demonstrated based on the said embodiment, this invention is not limited to this.

本発明に係る４階調フォトマスクの製造方法における第１の実施の形態である４階調グレートーンマスクの製造工程を示す工程図である。It is process drawing which shows the manufacturing process of the 4 gradation gray tone mask which is 1st Embodiment in the manufacturing method of the 4 gradation photomask which concerns on this invention. 図１の製造工程により製造された４階調グレートーンマスクを示し、（Ａ）が平面図、（Ｂ）が側断面図である。4A and 4B show a four-tone gray-tone mask manufactured by the manufacturing process of FIG. 1, in which FIG. 本発明に係る４階調フォトマスクの製造方法における第２の実施の形態である４階調グレートーンマスクの製造工程を示す工程図である。It is process drawing which shows the manufacturing process of the 4 gradation gray tone mask which is 2nd Embodiment in the manufacturing method of the 4 gradation photomask which concerns on this invention. 図３の製造工程により製造された４階調グレートーンマスクを示し、（Ａ）が平面図、（Ｂ）が側断面図である。4A and 4B show a four-tone gray-tone mask manufactured by the manufacturing process of FIG. 3, in which FIG. 3A is a plan view and FIG.

Explanation of symbols

１０グレートーンマスク（フォトマスク）
１３遮光部
１４透光部
１５Ａ第１半透光部
１５Ｂ第２半透光部
１６透光性基板
１７Ａ第１半透光膜
１７Ｂ第２半透光膜
１８遮光膜
２０フォトマスクブランク
２１第１レジストパターン
２４フォトマスクブランク
２５第２レジストパターン
３０グレートーンマスク（フォトマスク）
３３遮光部
３４透光部
３５Ａ第１半透光部
３５Ｂ第２半透光部
３７Ａ第１半透光膜
３７Ｂ第２半透光膜
３８遮光膜
４０フォトマスクブランク
４１第１レジストパターン
４４第２レジストパターン 10 Gray tone mask (photomask)
13 light-shielding part 14 light-transmitting part 15A first semi-light-transmitting part 15B second semi-light-transmitting part 16 light-transmitting substrate 17A first semi-light-transmitting film 17B second semi-light-transmitting film 18 light-shielding film 20 photomask blank 21 first Resist pattern 24 Photomask blank 25 Second resist pattern 30 Gray tone mask (photomask)
33 light-shielding part 34 light-transmitting part 35A first semi-light-transmitting part 35B second semi-light-transmitting part 37A first semi-light-transmitting film 37B second semi-light-transmitting film 38 light-shielding film 40 photomask blank 41 first resist pattern 44 second Resist pattern

Claims

In a method for manufacturing a four-tone photomask having a light-shielding portion, a light-transmitting portion, and a first semi-transmissive portion and a second semi-transmissive portion having different light transmittances, respectively.
Preparing a photomask blank in which a first semi-transparent film and a light-shielding film made of materials having resistance to mutual etching are sequentially formed on a translucent substrate;
Forming a first resist pattern having the light-transmitting portion and the second semi-light-transmitting portion as an opening region on the light-shielding film of the photomask blank;
Etching the light-shielding film using the first resist pattern as a mask, etching the first semi-transparent film, and further peeling the first resist pattern;
Next, forming a second semi-transparent film on the translucent substrate and the light shielding film,
Forming a second resist pattern having the light-transmitting portion and the first semi-light-transmitting portion as an opening region on the second semi-transmissive film;
The second semi-transparent film and the light-shielding film are etched using the second resist pattern as a mask, and then the second resist pattern is removed, so that the light-transmitting part, the light-shielding part, and the first semi-transparent part And forming the second semi-transparent part,
A method for manufacturing a four-tone photomask, comprising:

In a method for manufacturing a four-tone photomask having a light-shielding portion, a light-transmitting portion, and a first semi-transmissive portion and a second semi-transmissive portion having different light transmittances, respectively.
Preparing a photomask blank in which a first semi-transparent film and a light-shielding film made of materials having resistance to mutual etching are sequentially formed on a translucent substrate;
Forming a first resist pattern having the light-transmitting portion and the second semi-light-transmitting portion as an opening region on the light-shielding film of the photomask blank;
Etching the light shielding film using the first resist pattern as a mask, then peeling the first resist pattern and etching the first semi-transparent film using the light shielding film as a mask;
Next, forming a second semi-transparent film on the translucent substrate and the light shielding film,
Forming a second resist pattern having the light-transmitting portion and the first semi-light-transmitting portion as an opening region on the second semi-transmissive film;
The second semi-transparent film and the light-shielding film are etched using the second resist pattern as a mask, and then the second resist pattern is removed, so that the light-transmitting part, the light-shielding part, and the first semi-transparent part And forming the second semi-transparent part,
A method for manufacturing a four-tone photomask, comprising:

3. The method of manufacturing a four-tone photomask according to claim 1, wherein the second semi-transparent film is made of a material that can be etched in the same manner as the light-shielding film.

The first semi-transparent film is made of a material mainly composed of molybdenum silicide, and the light-shielding film and the second semi-transparent film are made of a material mainly composed of chromium. 4. A method for producing a four-tone photomask according to any one of 3 above.

A photomask blank for use in the method for producing a four-tone photomask according to claim 1,
A translucent substrate, a pattern in which a first semi-transparent film and a light-shielding film are stacked on the translucent substrate, and a second semi-transparent film formed on the translucent substrate and the pattern. A photomask blank comprising: a film;

In a method for manufacturing a four-tone photomask having a light-shielding portion, a light-transmitting portion, and a first semi-transmissive portion and a second semi-transmissive portion having different light transmittances, respectively.
A first semi-transparent film, a second semi-transparent film, and a light-shielding film are sequentially formed on the translucent substrate, and the first semi-transparent film, the light-shielding film, and the second semi-transparent film are formed. Preparing a photomask blank made of a material resistant to mutual etching;
Forming a first resist pattern having the light-transmitting portion and the first semi-light-transmitting portion as an opening region on the light-shielding film of the photomask blank;
Etching the light-shielding film using the first resist pattern as a mask, etching the second semi-transparent film, and further peeling the first resist pattern;
Next, a step of forming a second resist pattern having the light-transmitting portion and the second semi-light-transmitting portion as opening regions;
After the light shielding film and the first semi-transparent film are etched using the second resist pattern as a mask, the second resist pattern is removed, and the light transmitting part, the light shielding part, and the first semi light transmitting part are removed. And forming the second semi-transparent part,
A method for manufacturing a four-tone photomask, comprising:

In a method for manufacturing a four-tone photomask having a light-shielding portion, a light-transmitting portion, and a first semi-transmissive portion and a second semi-transmissive portion having different light transmittances, respectively.
A first semi-transparent film, a second semi-transparent film, and a light-shielding film are sequentially formed on the translucent substrate, and the first semi-transparent film, the light-shielding film, and the second semi-transparent film are formed. Preparing a photomask blank made of a material resistant to mutual etching;
Forming a first resist pattern having the light-transmitting portion and the first semi-light-transmitting portion as an opening region on the light-shielding film of the photomask blank;
Etching the light shielding film using the first resist pattern as a mask, then peeling the first resist pattern and etching the second semi-transparent film using the light shielding film as a mask;
Next, a step of forming a second resist pattern having the light-transmitting portion and the second semi-light-transmitting portion as opening regions;
After the light shielding film and the first semi-transparent film are etched using the second resist pattern as a mask, the second resist pattern is removed, and the light transmitting part, the light shielding part, and the first semi light transmitting part are removed. And forming the second semi-transparent part,
A method for manufacturing a four-tone photomask, comprising:

8. The method for manufacturing a four-tone photomask according to claim 6, wherein the first semi-transparent film and the light-shielding film can be etched with the same etching agent.

9. The second semi-transparent film is made of a material containing molybdenum silicide as a main component, and the first semi-transparent film and the light shielding film are made of a material containing chromium as a main component. A method for producing the four-tone photomask as described.

A photomask blank for use in the method for producing a four-tone photomask according to claim 6,
A photomask blank comprising: a light-transmitting substrate; and a first semi-light-transmitting film, a second semi-light-transmitting film, and a light-shielding film that are sequentially stacked on the light-transmitting substrate.