JP5372403B2 - Multi-tone photomask and pattern transfer method - Google Patents

Multi-tone photomask and pattern transfer method Download PDF

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JP5372403B2
JP5372403B2 JP2008119970A JP2008119970A JP5372403B2 JP 5372403 B2 JP5372403 B2 JP 5372403B2 JP 2008119970 A JP2008119970 A JP 2008119970A JP 2008119970 A JP2008119970 A JP 2008119970A JP 5372403 B2 JP5372403 B2 JP 5372403B2
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JP2009271213A (en
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道明 佐野
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Hoya Corp
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
    • G03F1/36—Masks having proximity correction features; Preparation thereof, e.g. optical proximity correction [OPC] design processes
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
    • G03F1/54—Absorbers, e.g. of opaque materials
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
    • G03F1/68—Preparation processes not covered by groups G03F1/20 - G03F1/50
    • G03F1/76—Patterning of masks by imaging
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
    • G03F1/68—Preparation processes not covered by groups G03F1/20 - G03F1/50
    • G03F1/80—Etching
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/027—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34
    • H01L21/033—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34 comprising inorganic layers
    • H01L21/0332—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34 comprising inorganic layers characterised by their composition, e.g. multilayer masks, materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/027—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34
    • H01L21/033—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34 comprising inorganic layers
    • H01L21/0334—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34 comprising inorganic layers characterised by their size, orientation, disposition, behaviour, shape, in horizontal or vertical plane
    • H01L21/0337—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34 comprising inorganic layers characterised by their size, orientation, disposition, behaviour, shape, in horizontal or vertical plane characterised by the process involved to create the mask, e.g. lift-off masks, sidewalls, or to modify the mask, e.g. pre-treatment, post-treatment

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Manufacturing & Machinery (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Preparing Plates And Mask In Photomechanical Process (AREA)
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Abstract

PURPOSE: A multi-gray photomask, a manufacturing method thereof, and a method for transferring the pattern are provided to design a gray tone part with plural transmissivity using a semi-transmissive layer with the required transmissivity. CONSTITUTION: A mask pattern is comprised of a shielding unit(11), a transmissive unit(12), and a semi-transmissive unit on a transparent substrate(14). The shielding unit is formed by a shielding layer(15) on the transparent substrate. The transmissive unit is formed by exposing the transparent substrate. A first semi-transmissive unit is comprised by forming a semi-transmissive layer on the transparent substrate. A second semi-transmissive unit has a minute pattern with a line width below the resolution limit under an exposure condition. The shielding layer is made of the material with chrome as a main component.

Description

本発明は、液晶表示装置（Liquid Crystal Display：以下、ＬＣＤと称する）製造等に好適に用いられる多階調フォトマスク及びその製造方法、並びに当該フォトマスクを用いたパターン転写方法に関するものである。  The present invention relates to a multi-tone photomask suitably used for manufacturing a liquid crystal display (Liquid Crystal Display: hereinafter referred to as LCD), a manufacturing method thereof, and a pattern transfer method using the photomask.

現在、ＬＣＤの分野において、薄膜トランジスタ液晶表示装置（Thin Film Transistor Liquid Crystal Display：以下、ＴＦＴ−ＬＣＤと呼ぶ）は、ＣＲＴ（陰極線管）に比較して、薄型にしやすく消費電力が低いという利点から、現在商品化が急速に進んでいる。ＴＦＴ−ＬＣＤは、マトリックス状に配列された各画素にＴＦＴが配列された構造のＴＦＴ基板と、各画素に対応して、レッド、グリーン、及びブルーの画素パターンが配列されたカラーフィルターが液晶相の介在の下に重ね合わされた概略構造を有する。ＴＦＴ−ＬＣＤでは、製造工程数が多く、ＴＦＴ基板だけでも５〜６枚のフォトマスクを用いて製造されていた。このような状況の下、ＴＦＴ基板の製造を４枚のフォトマスクを用いて行う方法が提案されている。   At present, in the field of LCD, a thin film transistor liquid crystal display (hereinafter referred to as TFT-LCD) is advantageous in that it is thinner and has lower power consumption than a CRT (cathode ray tube). Commercialization is progressing rapidly. A TFT-LCD includes a TFT substrate having a structure in which TFTs are arranged in pixels arranged in a matrix, and a color filter in which red, green, and blue pixel patterns are arranged corresponding to each pixel. It has a schematic structure superimposed under the intervention of. In TFT-LCD, the number of manufacturing processes is large, and the TFT substrate alone is manufactured using 5 to 6 photomasks. Under such circumstances, a method of manufacturing a TFT substrate using four photomasks has been proposed.

この方法は、遮光部と透光部の他に半透光部（グレートーン部）を有する多階調マスク(又はグレートーンマスク)と称されるフォトマスクを用いることにより、使用するマスク枚数を低減するというものである。ここで、半透光部とは、マスクを使用してパターンを被転写体に転写する際、透過する露光光の透過量を所定量低減させ、被転写体上のフォトレジスト膜の現像後の残膜量を制御する部分をいう。   This method uses a photomask called a multi-tone mask (or gray tone mask) having a semi-transparent portion (gray tone portion) in addition to the light shielding portion and the translucent portion, thereby reducing the number of masks to be used. It is to reduce. Here, the semi-transparent portion means that when a pattern is transferred to a transfer object using a mask, the amount of exposure light transmitted therethrough is reduced by a predetermined amount, and the photoresist film on the transfer object after development is developed. The part that controls the amount of remaining film.

ここで用いられるグレートーンマスクとしては、半透光部が、グレートーンマスクを使用するＬＣＤ用露光機の解像限界以下の微細パターンで形成されている構造のものが特許文献１により知られている。また、半透光部を半透過性の半透光膜によって形成する構造のものも従来知られている。何れの構造のものであっても、この半透光部での露光量を所定量少なくして露光することが出来、被転写体上に、レジスト残膜値の異なる２つの転写パターンを転写することができることから、１枚のグレートーンマスクを用いて従来のフォトマスク２枚分の工程が実施されることにより、TFT-ＬＣＤなどの電子デバイスを製造する際に、必要なマスク枚数が削減される。   As a gray tone mask used here, Patent Document 1 discloses a structure in which a semi-transparent portion is formed with a fine pattern below the resolution limit of an LCD exposure machine using a gray tone mask. Yes. In addition, a structure in which the semi-transparent portion is formed of a semi-transparent semi-transparent film is also conventionally known. Regardless of the structure, it is possible to expose the semi-translucent portion with a predetermined amount of light exposure, and transfer two transfer patterns having different resist residual film values onto the transfer target. Therefore, the number of masks required for manufacturing electronic devices such as TFT-LCDs can be reduced by carrying out the process of two conventional photomasks using one graytone mask. The

また、遮光部と透光部の他に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階調フォトマスクをリソグラフィ工程により少ない描画回数で製造できる４階調フォトマスクの製造方法が下記特許文献２に開示されている。   In addition to the light-shielding portion and the light-transmitting portion, a 4-tone photomask having a first semi-transparent portion and a second semi-transparent portion having different light transmittances can be manufactured by a lithography process with a small number of times of drawing. A photomask manufacturing method is disclosed in Patent Document 2 below.

特開２００２−１９６４７４号公報JP 2002-196474 A 特開２００７−２４９１９８号公報JP 2007-249198 A

特許文献１に開示されたグレートーンマスクは、遮光部と透光部と半透光部とを有し、露光光透過率を３段階に変化させる３階調のフォトマスクである。しかしながら、半透光部が、遮光膜のパターンによって形成されているため、そのグレートーン部の露光光透過率制約がある。例えば、均一に描画、パターニングできる線幅には制限があり、線幅が小さくなるにつれて、その均一性は劣化し、最終的には描画限界に至る。従って、比較的高透過率のグレートーン部を形成しようとしても、所望の描画、パターニングが行なえず、結局、露光条件に応じて、所定透過率以下のものしか設計できない不都合がある。   The gray-tone mask disclosed in Patent Document 1 is a three-tone photomask having a light-shielding portion, a light-transmitting portion, and a semi-light-transmitting portion, and changing the exposure light transmittance in three stages. However, since the semi-transparent portion is formed by the pattern of the light shielding film, there is a limitation on the exposure light transmittance of the gray tone portion. For example, there is a limit to the line width that can be drawn and patterned uniformly. As the line width decreases, the uniformity deteriorates and eventually reaches the drawing limit. Therefore, even if an attempt is made to form a gray tone portion having a relatively high transmittance, the desired drawing and patterning cannot be performed. Consequently, there is a disadvantage that only a predetermined transmittance or less can be designed according to the exposure conditions.

また、上記特許文献２に開示された４階調フォトマスクの製造方法によれば、グレートーン部に所望の透過率をもつ半透光膜を使用するので、その素材や膜厚を選択すれば、比較的自由に、所望の複数の透過率をもったグレートーン部を設計することができる。但し、階調数が増加するにつれて、新たな膜を成膜する必要があるため、成膜工程を増加させ、それに伴って欠陥発生の確率が上がるという不都合がある。更に、半透光膜を用いた場合でも、高透過率のものは素材に制約があり、更に、膜厚が極端に薄くなると、膜厚の面内分布が劣化しそれに伴い透過率分布も劣化する。
従って、３階調を超える多階調マスクの作製において、成膜工程などを増やさずに、透過率の異なる半透光部を作り分けること、更には、比較的高い透過率をもつ半透光部を有する多階調マスクを作製する上では、問題点があった。 In addition, according to the method for manufacturing a four-tone photomask disclosed in Patent Document 2, a semi-transparent film having a desired transmittance is used in the gray tone portion, so that the material and film thickness can be selected. The gray tone portion having a desired plurality of transmittances can be designed relatively freely. However, since it is necessary to form a new film as the number of gradations increases, there is an inconvenience that the number of film forming steps is increased and the probability of occurrence of defects is increased accordingly. Furthermore, even when a semi-transparent film is used, the material with high transmittance has restrictions on the material. Further, when the film thickness becomes extremely thin, the in-plane distribution of the film thickness deteriorates and the transmittance distribution also deteriorates accordingly. To do.
Therefore, in the production of a multi-tone mask exceeding 3 gradations, it is possible to create semi-transparent portions having different transmittances without increasing the number of film forming processes, and further, semi-transparent light having a relatively high transmittance. There is a problem in manufacturing a multi-tone mask having a portion.

本発明は、上記従来の事情に鑑みてなされたものであり、遮光部、透光部、半透光部を有し、従来の３階調を超えるフォトマスクとして用いることが可能な、所望の透過率をもつ多階調フォトマスクを提供することを第１の目的とする。また、本発明は、このような多階調フォトマスクを、効率的で、かつ欠陥発生の確率の低い簡便な工程によって製造できる多階調フォトマスクの製造方法を提供することを第２の目的とする。さらに、本発明は、上記多階調フォトマスクを用いたパターン転写方法を提供することを第３の目的とする。   The present invention has been made in view of the above-described conventional circumstances, and has a light-shielding portion, a light-transmitting portion, and a semi-light-transmitting portion, and can be used as a desired photomask exceeding three gradations. A first object is to provide a multi-tone photomask having transmittance. It is a second object of the present invention to provide a method for manufacturing a multi-tone photomask capable of manufacturing such a multi-tone photomask by a simple process that is efficient and has a low probability of occurrence of defects. And Furthermore, a third object of the present invention is to provide a pattern transfer method using the multi-tone photomask.

上記課題を解決するため、本発明は以下の構成を有する。
（構成１）透明基板上に、遮光部、透光部、及び露光光透過率を所定量低減させる半透光部からなるマスクパターンを有し、前記遮光部は、少なくとも前記透明基板上に形成された遮光膜により形成され、前記透光部は、露出した前記透明基板により形成され、前記半透光部は、少なくとも、前記透明基板上に形成された半透光膜によりなる第１半透光部と、前記透明基板上に形成された、前記半透光膜の微細パターン、前記遮光膜の微細パターン、及び前記半透光膜及び前記遮光膜が形成されていない微細隙間を含み、露光条件下における解像限界以下の線幅をもつ微細パターンが形成されてなる第２半透光部とを有していることを特徴とする多階調フォトマスク。 In order to solve the above problems, the present invention has the following configuration.
(Structure 1) A mask pattern including a light-shielding portion, a light-transmitting portion, and a semi-light-transmitting portion that reduces the exposure light transmittance by a predetermined amount is provided on the transparent substrate, and the light-shielding portion is formed on at least the transparent substrate. The translucent part is formed by the exposed transparent substrate, and the semi-translucent part is formed by at least a first semi-transparent film formed on the transparent substrate. An exposure including a light portion and a fine pattern of the semi-transparent film, a fine pattern of the light-shielding film, and a fine gap in which the semi-transparent film and the light-shielding film are not formed, formed on the transparent substrate A multi-tone photomask comprising: a second semi-transparent portion formed with a fine pattern having a line width less than a resolution limit under conditions.

上記本発明のフォトマスクは、透明基板上に半透光膜が形成されてなる第１半透光部を有する。更に、半透光膜の微細パターンと遮光膜の微細パターンと、膜が形成されず、基板表面が露出した、微細隙間とを含み、露光条件下における解像限界以下の線幅をもつ微細パターンが形成されてなる第２半透光部をも備える。すなわち、第１半透光部が微細パターンを有しない半透光膜によってなるのに対し、第２半透光部は、微細パターンを有してなる。ここで、「露光条件下における解像限界以下の線幅をもつ微細パターン」とは、半透光膜部分の線幅、又は遮光膜部分の線幅、或いは、半透光膜または遮光膜パターン間に形成された隙間（スペース）部分の線幅のいずれかが、露光条件下における解像限界以下の寸法であることをいう。すなわち、半透光膜によって形成されたパターン又は遮光膜によって形成されたパターンが、そのパターン形状が解像されない程度に、微細な線幅、又はスペース幅を有している。好ましくは、第２半透光部において、半透光膜の微細パターン、遮光膜の微細パターン、微細隙間の線幅のいずれもが、露光条件下で、解像限界以下であることが望ましい。   The photomask of the present invention has a first semi-transparent portion in which a semi-transparent film is formed on a transparent substrate. Furthermore, a fine pattern having a line width less than the resolution limit under exposure conditions, including a fine pattern of a semi-transparent film and a fine pattern of a light-shielding film, and a fine gap where a film is not formed and the substrate surface is exposed. A second semi-transparent portion formed of That is, the first semi-transparent portion is formed of a semi-transparent film having no fine pattern, whereas the second semi-transparent portion has a fine pattern. Here, “a fine pattern having a line width less than or equal to the resolution limit under exposure conditions” means a line width of a semi-transparent film part, a line width of a light-shielding film part, or a semi-transparent film or a light-shielding film pattern Any one of the line widths of the gaps formed between them is a dimension that is not more than the resolution limit under the exposure conditions. That is, the pattern formed by the semi-transparent film or the pattern formed by the light shielding film has a fine line width or space width to such an extent that the pattern shape is not resolved. Preferably, in the second semi-transparent portion, it is desirable that all of the fine pattern of the semi-transparent film, the fine pattern of the light shielding film, and the line width of the fine gap are not more than the resolution limit under the exposure conditions.

（構成２）透明基板上に、遮光部、透光部、及び露光光透過率を所定量低減させる半透光部からなるマスクパターンを有し、前記遮光部は、少なくとも前記透明基板上に形成された遮光膜により形成され、前記透光部は、露出した前記透明基板により形成され、前記半透光部は、少なくとも、前記透明基板上に形成された半透光膜によりなる第１半透光部と、前記透明基板上に形成された、前記半透光膜の微細パターンと前記遮光膜の微細パターンとからなる露光条件下における解像限界以下の線幅をもつ微細パターンが形成されてなる第３半透光部とを有していることを特徴とする多階調フォトマスク。
上記本発明のフォトマスクでは、前記第１半透光部に加えて、更に、半透光膜の微細パターンと遮光膜の微細パターンとからなる露光条件下における解像限界以下の線幅をもつ微細パターンが形成されてなる第３半透光部をも備える。この第３半透光部では、「露光条件下における解像限界以下の線幅をもつ微細パターン」とは、半透光膜部分の線幅、又は遮光膜部分の線幅のいずれかが、露光条件下における解像限界以下の寸法であることをいう。すなわち、半透光膜によって形成されたパターン又は遮光膜によって形成されたパターンが、そのパターン形状が解像されない程度に微細な線幅を有している。なお、第３半透光部は、透明基板が露出した隙間（スペース部分）は有していない。 (Configuration 2) A mask pattern including a light shielding part, a light transmitting part, and a semi-light transmitting part for reducing the exposure light transmittance by a predetermined amount is provided on the transparent substrate, and the light shielding part is formed on at least the transparent substrate. The translucent part is formed by the exposed transparent substrate, and the semi-translucent part is formed by at least a first semi-transparent film formed on the transparent substrate. A fine pattern having a line width equal to or less than a resolution limit under an exposure condition formed of an optical part and a fine pattern of the semi-transparent film and a fine pattern of the light-shielding film formed on the transparent substrate is formed. And a third semi-transparent portion.
In the photomask of the present invention, in addition to the first semi-transparent portion, the photomask further has a line width equal to or less than a resolution limit under an exposure condition including a fine pattern of the semi-transparent film and a fine pattern of the light-shielding film. A third semi-transparent part formed with a fine pattern is also provided. In the third semi-transparent portion, “a fine pattern having a line width less than or equal to the resolution limit under exposure conditions” is either the line width of the semi-transparent film portion or the line width of the light-shielding film portion. It means that the dimensions are below the resolution limit under exposure conditions. That is, the pattern formed by the semi-transparent film or the pattern formed by the light-shielding film has a line width so fine that the pattern shape is not resolved. In addition, the 3rd semi-translucent part does not have the clearance gap (space part) which the transparent substrate exposed.

（構成３）前記遮光膜はクロムを主成分とした材料からなり、前記半透光膜は金属シリサイドを主成分とした材料からなることを特徴とする構成１又は２に記載の多階調フォトマスク。
（構成４）前記遮光部は、少なくとも前記半透光膜と前記遮光膜が積層されてなり、前記半透光膜と前記遮光膜の間に、エッチングストッパ膜を有することを特徴とする構成１又は２に記載の多階調フォトマスク。 (Structure 3) The multi-tone photo according to Structure 1 or 2, wherein the light shielding film is made of a material containing chromium as a main component, and the semi-transparent film is made of a material containing metal silicide as a main component. mask.
(Structure 4) Structure 1 is characterized in that at least the semi-transparent film and the light-shield film are stacked, and the light-shielding portion has an etching stopper film between the semi-transparent film and the light-shield film. Or the multi-tone photomask of 2.

（構成５）透明基板上に、遮光部、透光部、及び露光光透過率を所定量低減させる半透光部からなるマスクパターンを有する多階調フォトマスクの製造方法であって、透明基板上に、半透光膜と遮光膜とをこの順に有するフォトマスクブランクを準備する工程と、前記フォトマスクブランクの前記遮光膜上に形成したレジスト膜を描画、現像して、所定の第１レジストパターンを形成する工程と、前記第１レジストパターンをマスクとして前記遮光膜をエッチングして遮光膜パターンを形成する工程と、前記第１レジストパターン又は遮光膜パターンをマスクとして前記半透光膜をエッチングする工程と、パターニングされた前記遮光膜及び前記半透光膜を含む基板上に形成したレジスト膜を描画、現像して第２レジストパターンを形成する工程と、前記第２レジストパターンをマスクとして露出した前記遮光膜をエッチングする工程と、を有し、前記第１レジストパターン及び第２レジストパターンの少なくとも一方に微細パターンを含み、前記透明基板上に形成された半透光膜及び遮光膜によりなる遮光部と、前記透明基板が露出してなる透光部と、前記透明基板上に形成された半透光膜によりなる半透光部と、前記透明基板上に、露光条件下における解像限界以下の線幅をもつ半透光膜の微細パターン及び露光条件下における解像限界以下の線幅をもつ遮光膜の微細パターンを含む半透光部とを形成することを特徴とする多階調フォトマスクの製造方法。 (Configuration 5) A method for producing a multi-tone photomask having a mask pattern comprising a light shielding portion, a light transmitting portion, and a semi-light transmitting portion for reducing the exposure light transmittance by a predetermined amount on a transparent substrate, the transparent substrate A step of preparing a photomask blank having a semi-transparent film and a light-shielding film in this order; and a resist film formed on the light-shielding film of the photomask blank is drawn and developed to form a predetermined first resist A step of forming a pattern, a step of etching the light shielding film using the first resist pattern as a mask to form a light shielding film pattern, and an etching of the semi-transparent film using the first resist pattern or the light shielding film pattern as a mask And drawing and developing a resist film formed on the substrate including the patterned light-shielding film and the semi-translucent film to form a second resist pattern And etching the light-shielding film exposed using the second resist pattern as a mask, wherein at least one of the first resist pattern and the second resist pattern includes a fine pattern, and is formed on the transparent substrate. A light-shielding portion made of the formed semi-light-transmitting film and light-shielding film, a light-transmitting portion in which the transparent substrate is exposed, a semi-light-transmissive portion made of a semi-light-transmitting film formed on the transparent substrate, and A semi-transparent portion including a fine pattern of a semi-transparent film having a line width below the resolution limit under exposure conditions and a fine pattern of a light-shielding film having a line width below the resolution limit under exposure conditions on a transparent substrate And forming a multi-tone photomask.

（構成６）透明基板上に、遮光部、透光部、及び露光光透過率を所定量低減させる半透光部からなるマスクパターンを有する多階調フォトマスクの製造方法であって、透明基板上に、半透光膜と遮光膜とをこの順に有するフォトマスクブランクを準備する工程と、前記フォトマスクブランクの前記遮光膜上に形成したレジスト膜を描画、現像して、所定の第１レジストパターンを形成する工程と、前記第１レジストパターンをマスクとして前記遮光膜をエッチングして遮光膜パターンを形成する工程と、パターニングされた前記遮光膜及び前記半透光膜を含む基板上に形成したレジスト膜を描画、現像して所定の第２レジストパターンを形成する工程と、前記第２レジストパターンをマスクとして露出した前記半透光膜又は前記遮光膜とその下の半透光膜をエッチングする工程と、を有し、前記第１レジストパターン及び第２レジストパターンの少なくとも一方に微細パターンを含み、前記透明基板上に形成された半透光膜及び遮光膜によりなる遮光部と、前記透明基板が露出してなる透光部と、前記透明基板上に形成された半透光膜によりなる半透光部と、前記透明基板上に露光条件下における解像限界以下の線幅をもつ半透光膜の微細パターン及び露光条件下における解像限界以下の線幅をもつ遮光膜の微細パターンを含む半透光部とを形成することを特徴とする多階調フォトマスクの製造方法。 (Structure 6) A method for producing a multi-tone photomask having a mask pattern comprising a light-shielding portion, a light-transmitting portion, and a semi-light-transmitting portion that reduces exposure light transmittance by a predetermined amount on a transparent substrate, the transparent substrate A step of preparing a photomask blank having a semi-transparent film and a light-shielding film in this order; and a resist film formed on the light-shielding film of the photomask blank is drawn and developed to form a predetermined first resist Forming a pattern, forming a light-shielding film pattern by etching the light-shielding film using the first resist pattern as a mask, and forming the patterned light-shielding film and the semi-transparent film on the substrate A step of drawing and developing a resist film to form a predetermined second resist pattern; the semi-transparent film or the light-shielding film exposed using the second resist pattern as a mask; and A step of etching the semitranslucent film, wherein at least one of the first resist pattern and the second resist pattern includes a fine pattern, and the semitranslucent film and the light shielding film are formed on the transparent substrate. A light-shielding portion, a light-transmitting portion formed by exposing the transparent substrate, a semi-light-transmitting portion formed of a semi-light-transmitting film formed on the transparent substrate, and a resolution limit under exposure conditions on the transparent substrate. Forming a fine pattern of a semi-transparent film having the following line width and a semi-transparent portion including a fine pattern of a light-shielding film having a line width less than a resolution limit under exposure conditions. Photomask manufacturing method.

（構成７）前記遮光膜と前記半透光膜は、エッチング選択性のある素材によってなることを特徴とする構成５又は６に記載の多階調フォトマスクの製造方法。
（構成８）前記遮光膜はクロムを主成分とした材料からなり、前記半透光膜は金属シリサイドを主成分とした材料からなることを特徴とする構成７に記載の多階調フォトマスクの製造方法。
（構成９）前記遮光膜と前記半透光膜の間に、エッチングストッパ膜を有することを特徴とする構成５又は６に記載の多階調フォトマスクの製造方法。 (Structure 7) The multi-tone photomask manufacturing method according to Structure 5 or 6, wherein the light shielding film and the semi-translucent film are made of a material having etching selectivity.
(Structure 8) The multi-tone photomask according to Structure 7, wherein the light shielding film is made of a material containing chromium as a main component, and the semi-transparent film is made of a material containing metal silicide as a main component. Production method.
(Structure 9) The method for producing a multi-tone photomask according to Structure 5 or 6, wherein an etching stopper film is provided between the light shielding film and the semi-transparent film.

（構成１０）透明基板上に、遮光部、透光部、及び露光光透過率を所定量低減させる半透光部からなるマスクパターンを有する多階調フォトマスクの製造方法であって、透明基板上に遮光膜を有するフォトマスクブランクを準備する工程と、前記フォトマスクブランクの前記遮光膜上に形成したレジスト膜を描画、現像して第１レジストパターンを形成する工程と、前記第１レジストパターンをマスクとして前記遮光膜をエッチングして遮光膜パターンを形成する工程と、前記第１レジストパターンを除去した後、パターニングされた前記遮光膜を含む基板上に半透光膜を形成する工程と、前記半透光膜上に形成したレジスト膜を描画、現像して第２レジストパターンを形成する工程と、前記第２レジストパターンをマスクとして露出した前記半透光膜、又は半透光膜及び前記遮光膜をエッチングする工程と、を有し、前記第１レジストパターン及び第２レジストパターンの少なくとも一方に微細パターンを含み、前記透明基板上に形成された遮光膜及び半透光膜によりなる遮光部と、前記透明基板が露出してなる透光部と、前記透明基板上に形成された半透光膜によりなる半透光部と、前記透明基板上に形成された露光条件下における解像限界以下の線幅をもつ半透光膜の微細パターン及び露光条件下における解像限界以下の線幅を持つ遮光膜の微細パターンを含む半透光部とを形成することを特徴とする多階調フォトマスクの製造方法。 (Configuration 10) A method for producing a multi-tone photomask having a mask pattern comprising a light shielding portion, a light transmitting portion, and a semi-light transmitting portion for reducing the exposure light transmittance by a predetermined amount on a transparent substrate, the transparent substrate A step of preparing a photomask blank having a light shielding film thereon, a step of drawing and developing a resist film formed on the light shielding film of the photomask blank to form a first resist pattern, and the first resist pattern Etching the light-shielding film using the mask as a mask to form a light-shielding film pattern; and removing the first resist pattern, and then forming a semi-transparent film on the substrate including the patterned light-shielding film; A step of drawing and developing a resist film formed on the semi-translucent film to form a second resist pattern, and before exposing the second resist pattern as a mask A semi-transparent film, or a step of etching the semi-transparent film and the light-shielding film, wherein at least one of the first resist pattern and the second resist pattern includes a fine pattern, and is formed on the transparent substrate. A light-shielding portion made of a light-shielding film and a semi-light-transmissive film, a light-transmissive portion in which the transparent substrate is exposed, a semi-light-transmissive portion made of a semi-light-transmissive film formed on the transparent substrate, and the transparent substrate A semi-transparent portion including a fine pattern of a semi-transparent film having a line width less than the resolution limit under the exposure conditions and a fine pattern of a light-shielding film having a line width less than the resolution limit under the exposure conditions formed above And forming a multi-tone photomask.

（構成１１）透明基板上に、遮光部、透光部、及び露光光透過率を所定量低減させる半透光部からなるマスクパターンを有し、前記遮光部は、少なくとも前記透明基板上に形成された遮光膜により形成され、前記透光部は、露出した前記透明基板により形成され、前記半透光部は、前記透明基板上に形成された半透光膜によりなる第１半透光部と、前記透明基板上に形成された、前記半透光膜の微細パターン、前記遮光膜の微細パターン、及び前記半透光膜及び前記遮光膜が形成されていない微細隙間を含み、露光条件下における解像限界以下の線幅をもつ微細パターンが形成されてなる第２半透光部、又は、前記半透光膜の微細パターンと前記遮光膜の微細パターンとからなる露光条件下における解像限界以下の線幅をもつ微細パターンが形成されてなる第３半透光部とを有していることを特徴とする多階調フォトマスク。
（構成１２）構成１乃至４のいずれか、または構成１１に記載の多階調フォトマスク、あるいは、構成５乃至１０のいずれかに記載の製造方法による多階調フォトマスクを用いて、被転写体に露光光を照射する露光工程を有し、被転写体上に多階調の転写パターンを形成することを特徴とするパターン転写方法。 (Configuration 11) A mask pattern including a light-shielding portion, a light-transmitting portion, and a semi-light-transmitting portion that reduces the exposure light transmittance by a predetermined amount is formed on the transparent substrate, and the light-shielding portion is formed on at least the transparent substrate. The light-transmitting part is formed by the exposed transparent substrate, and the semi-transparent part is a first semi-transparent part formed by a semi-transparent film formed on the transparent substrate. And a fine pattern of the semi-translucent film, a fine pattern of the light-shielding film, and a fine gap in which the semi-transparent film and the light-shielding film are not formed, formed on the transparent substrate, and under exposure conditions The second semi-transmission part in which a fine pattern having a line width less than or equal to the resolution limit in the above is formed, or resolution under exposure conditions comprising the fine pattern of the semi-transparent film and the fine pattern of the light-shielding film A fine pattern with a line width less than the limit Multi-tone photomask, characterized in that a third semi-light-transmitting portion made are composed.
(Configuration 12) Transferred using the multi-tone photomask according to any one of configurations 1 to 4, or the configuration 11, or the multi-tone photomask according to the manufacturing method according to any of the configurations 5 to 10. A pattern transfer method comprising an exposure step of irradiating a body with exposure light, and forming a multi-tone transfer pattern on a transfer target.

本発明によれば、３階調を超えるフォトマスクとして用いることが可能な多階調フォトマスクが得られる。
また、本発明の多階調フォトマスクの製造方法によれば、このような多階調フォトマスクを、遮光膜と半透光膜との組み合わせを用い、フォトリソグラフィ法によって、効率的で、かつ欠陥発生の確率の低い簡便な工程によって製造することができる。本発明の多階調フォトマスクは、透過率の高い半透光部を含み、所望の透過率を有する半透光部を簡便に作製できる。 According to the present invention, a multi-tone photomask that can be used as a photomask having more than three tones can be obtained.
In addition, according to the method of manufacturing a multi-tone photomask of the present invention, such a multi-tone photomask can be efficiently used by a photolithography method using a combination of a light-shielding film and a semi-transparent film. It can be manufactured by a simple process with a low probability of occurrence of defects. The multi-tone photomask of the present invention includes a semi-transparent portion having a high transmittance, and a semi-transparent portion having a desired transmittance can be easily manufactured.

また、本発明に係る多階調フォトマスクを用いたパターン転写方法によれば、精度の高い多階調のパターン転写を実施することができ、またその結果、例えばＴＦＴ基板の製造等においてマスク枚数の大幅な削減が可能になる。また、後述するように、フォトマスク上の所定の半透光部について、パターンの線幅にかかわらず被転写体への露光量を一定にする（一致させる）ことができる。   Further, according to the pattern transfer method using the multi-tone photomask according to the present invention, high-precision multi-tone pattern transfer can be carried out. Can be significantly reduced. Further, as will be described later, the exposure amount to the transfer target can be made constant (matched) regardless of the line width of the pattern for a predetermined semi-transparent portion on the 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。
［第１の実施の形態］
図１は、本発明に係る多階調フォトマスクの第１の実施の形態と、当該多階調フォトマスクを用いたパターン転写方法を説明するための断面図である。
図１に示す多階調フォトマスク１０は、例えば液晶表示装置（ＬＣＤ）の薄膜トランジスタ（ＴＦＴ）やカラーフィルター、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の多階調グレートーンマスクとして用いることができるものであり、図１に示す被転写体２０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２３を形成するものである。なお、図１中において符号２２は、被転写体２０において基板２１上に積層された複数層の積層膜を示す。 The best mode for carrying out the present invention will be described below with reference to the drawings.
[First Embodiment]
FIG. 1 is a cross-sectional view for explaining a first embodiment of a multi-tone photomask according to the present invention and a pattern transfer method using the multi-tone photomask.
The multi-tone photomask 10 shown in FIG. 1 is used as a multi-tone gray tone mask for manufacturing a thin film transistor (TFT), a color filter, a plasma display panel (PDP), etc. of a liquid crystal display device (LCD), for example. A resist pattern 23 having different thicknesses stepwise or continuously is formed on the transfer target 20 shown in FIG. In FIG. 1, reference numeral 22 denotes a multi-layered film laminated on the substrate 21 in the transfer target 20.

上記本実施の形態のフォトマスク１０は、具体的には、当該フォトマスク１０の使用時に露光光を遮光（透過率が略０％）させる遮光部１１と、ガラス基板等の透明基板１４の表面が露出して露光光を透過させる透光部１２と、透光部１２の露光光透過率を１００％としたとき透過率を１０〜８０％程度、好ましくは、２０〜７０％程度の範囲内に低減させ、この範囲内において露光光透過率が例えば７段階に異なる、第1半透光部１３Ａ、第２半透光部１３Ｂ、第３半透光部１３Ｃ、第４半透光部１３Ｅ、第５半透光部１３Ｆ、および第６半透光部１３Ｄを有して構成されている。本実施の形態では、上記遮光部１１は、透明基板１４上に、光半透過性の半透光膜１６、遮光層１５ａ及び反射防止層１５ｂの積層からなる遮光膜１５が順に設けられて形成されている。また、上記のとおり、透光部１２は、透明基板１４の表面が露出している領域である。また、上記半透光部のうちの第１半透光部１３Ａは、透明基板１４上に成膜された光半透過性の半透光膜１６により形成されている。第１半透光部１３Ａの露光光透過率が所望の値となるように、上記半透光膜１６の材質及び膜厚が設定されている。また、第２半透光部１３Ｂは、上記半透光膜１６の微細パターン１７と、上記半透光膜１６と遮光膜１５の積層膜の微細パターン１８と、膜が形成されていない隙間部分（スペース部分）とからなる露光条件下における解像限界以下の線幅をもつ微細パターンが形成されて構成されている。
半透光膜微細パターンと遮光膜微細パターン、微細隙間のそれぞれの線幅、面積比は、所望の露光光透過率に基づいて決定することができる。
第２半透光部１３Ｂの露光光透過率が所望の値となるように、上記半透光膜１６で形成された微細パターン１７の線幅及び／又は上記遮光膜１５で形成された微細パターン１８の線幅及び／又は上記微細隙間（スペース部分）の線幅が設定されている。さらに、第３半透光部１３Ｃは、上記半透光膜１６と遮光膜１５の積層膜の微細パターン１８と、該微細パターン１８間に形成された上記半透光膜１６の微細パターンとからなる露光条件下における解像限界以下の線幅をもつ微細パターンが形成されて構成されている。第３半透光部１３Ｃの露光光透過率が所望の値となるように、上記半透光膜１６で形成された微細パターンの線幅及び上記遮光膜１５で形成された微細パターン１８の線幅が設定されている。 Specifically, the photomask 10 of the present embodiment includes a light shielding portion 11 that shields exposure light (transmittance is approximately 0%) when the photomask 10 is used, and a surface of a transparent substrate 14 such as a glass substrate. Is exposed and transmits the exposure light, and the exposure light transmittance of the light transmitting portion 12 is 100%, the transmittance is about 10 to 80%, preferably about 20 to 70%. The first light-transmitting portion 13A, the second light-transmitting portion 13B, the third light-transmitting portion 13C, and the fourth light-transmitting portion 13E having different exposure light transmittances in, for example, seven levels within this range. , A fifth semi-transparent portion 13F, and a sixth semi-transparent portion 13D. In the present embodiment, the light-shielding portion 11 is formed by sequentially providing a light-shielding film 15 made of a laminate of a light-semitransmissive semi-transparent film 16, a light-shielding layer 15a, and an antireflection layer 15b on a transparent substrate 14. Has been. Further, as described above, the light transmitting portion 12 is a region where the surface of the transparent substrate 14 is exposed. In addition, the first semi-transmissive portion 13 </ b> A among the semi-transmissive portions is formed by a light semi-transmissive semi-transmissive film 16 formed on the transparent substrate 14. The material and film thickness of the semi-transmissive film 16 are set so that the exposure light transmittance of the first semi-transmissive part 13A has a desired value. The second semi-transparent portion 13B includes a fine pattern 17 of the semi-transparent film 16, a fine pattern 18 of the laminated film of the semi-transparent film 16 and the light shielding film 15, and a gap portion where no film is formed. A fine pattern having a line width equal to or smaller than the resolution limit under the exposure conditions including (space portion) is formed.
The line width and area ratio of each of the semitransparent film fine pattern, the light shielding film fine pattern, and the fine gap can be determined based on the desired exposure light transmittance.
The line width of the fine pattern 17 formed by the semi-transparent film 16 and / or the fine pattern formed by the light-shielding film 15 so that the exposure light transmittance of the second semi-transparent part 13B becomes a desired value. A line width of 18 and / or a line width of the fine gap (space portion) is set. Further, the third semi-transparent portion 13C includes a fine pattern 18 of the laminated film of the semi-transparent film 16 and the light shielding film 15 and a fine pattern of the semi-transparent film 16 formed between the fine patterns 18. A fine pattern having a line width less than the resolution limit under the exposure conditions is formed. The line width of the fine pattern formed by the semi-transparent film 16 and the line of the fine pattern 18 formed by the light-shielding film 15 so that the exposure light transmittance of the third semi-transparent portion 13C becomes a desired value. The width is set.

また、第４半透光部１３Ｅは、上記半透光膜１６で形成された露光条件下において解像限界以下の微細パターン１７により構成されている。第４半透光部１３Ｅの露光光透過率が所望の値となるように、上記半透光膜１６で形成された微細パターン１７の線幅が設定されている。さらに第５半透光部１３Ｆは、上記半透光膜１６と遮光膜１５の積層膜で形成された露光条件下において解像限界以下の微細パターン１８により構成されている。第５半透光部１３Ｆについても露光光透過率が所望の値となるように、上記半透光膜１６と遮光膜１５の積層膜で形成された微細パターン１８の線幅が設定されている。
さらに、第６半透光部１３Ｄは、上記第３半透光部１３Ｃにおける半透光膜１６で形成された微細パターンの線幅と遮光膜１５で形成された微細パターン１８の線幅が同一幅ではなくて異なる幅に設定されている。図１には、半透光膜１６と遮光膜１５の積層膜による微細パターンの線幅が、半透光膜１６の微細パターンの線幅に対して広い場合と狭い場合を示し、この第６半透光部１３Ｄの領域において露光光透過率が２段階に異なる。 Further, the fourth semi-transparent portion 13E is constituted by a fine pattern 17 having a resolution limit or less under the exposure conditions formed by the semi-transparent film 16. The line width of the fine pattern 17 formed by the semi-transparent film 16 is set so that the exposure light transmittance of the fourth semi-transparent portion 13E becomes a desired value. Further, the fifth semi-transparent portion 13F is constituted by a fine pattern 18 having a resolution limit or less under the exposure conditions formed by the laminated film of the semi-transparent film 16 and the light shielding film 15. The line width of the fine pattern 18 formed of the laminated film of the semi-transparent film 16 and the light shielding film 15 is set so that the exposure light transmittance becomes a desired value also for the fifth semi-transparent portion 13F. .
Further, in the sixth semi-transparent portion 13D, the line width of the fine pattern formed by the semi-transparent film 16 in the third semi-transparent portion 13C and the line width of the fine pattern 18 formed by the light shielding film 15 are the same. It is set to a different width, not a width. FIG. 1 shows a case where the line width of the fine pattern by the laminated film of the semi-transparent film 16 and the light shielding film 15 is wider and narrower than the line width of the fine pattern of the semi-transparent film 16. The exposure light transmittance is different in two steps in the region of the semi-translucent portion 13D.

したがって、本実施の形態に係る上記フォトマスク１０は、露光光透過率が９段階に異なる９階調のフォトマスクとなっている。例えば、第１〜第６半透光部１３Ａから１３Ｆの光透過率は、透光部を１００％としたとき、それぞれ、２０％、３０％、４０％、５０％、６０％、７０％、８０％程度とすることができる。なお、図１に示す遮光部１１、透光部１２、及び半透光部１３Ａ〜１３Ｆのパターン形状はあくまでも一例である。もちろん、上記態様を参照し、第２〜第６半透光部のうち、例えば第２半透光部１３Ｂのみを採用すれば、露光光透過率が４段階に異なる４階調のフォトマスクとして使用することができる。また、第２〜第６半透光部のうち、例えば第２半透光部１３Ｂと第３半透光部１３Ｃのみを採用すれば、露光光透過率が５段階に異なる５階調のフォトマスクとして使用することができる。またここで、例えば第２半透光部１３Ｂ〜第５半透光部１３Ｆにおける、微細パターンの線幅を、領域によって変更すれば（例えば第６半透光部１３Ｄのように）、更に、多階調のフォトマスクを製造することももちろん可能であり、また、線幅を連続的に変化させて、光透過率が傾斜する半透光部を形成することもできる。   Therefore, the photomask 10 according to the present embodiment is a nine-tone photomask having different exposure light transmittances in nine stages. For example, the light transmittances of the first to sixth semi-transmissive parts 13A to 13F are 20%, 30%, 40%, 50%, 60%, 70%, respectively, when the light transmissive part is 100%. It can be about 80%. In addition, the pattern shape of the light-shielding part 11, the translucent part 12, and the semi-transparent parts 13A-13F shown in FIG. 1 is an example to the last. Of course, referring to the above embodiment, if only the second semi-transparent portion 13B, for example, of the second to sixth semi-transparent portions is employed, a four-tone photomask having different exposure light transmittances in four stages can be obtained. Can be used. Further, among the second to sixth semi-transparent portions, for example, if only the second semi-transparent portion 13B and the third semi-transparent portion 13C are adopted, the exposure light transmittance is a five-gradation photo having five levels. Can be used as a mask. Further, here, for example, if the line width of the fine pattern in the second semi-transparent part 13B to the fifth semi-transparent part 13F is changed depending on the region (for example, like the sixth semi-transparent part 13D), Of course, it is possible to manufacture a multi-tone photomask, and it is also possible to continuously change the line width to form a semi-translucent portion where the light transmittance is inclined.

上述のような多階調フォトマスク１０を使用して、被転写体２０へのパターン転写を行ったときに、遮光部１１では露光光が実質的に透過せず、透光部１２では露光光が透過し、第１〜第６半透光部１３Ａ〜１３Ｆでは各々の光透過率に応じて露光光が低減される。そのため、被転写体２０上に塗布したレジスト膜（ここではポジ型フォトレジスト膜）は、パターン転写後、現像を経たとき、上記遮光部１１に対応する部分で膜厚が最も厚くなる。また、上記第１〜第６半透光部１３Ａ〜１３Ｆに対応する部分ではいずれも遮光部１１に対応する部分の膜厚よりも薄くなるが、各半透光部の光透過率に応じて段階的に膜厚が薄くなる。また、透光部１２に対応する部分では膜がない。その結果、本実施の形態のフォトマスク１０では、膜厚が９段階に異なる（そのうちの１段階は膜がない）レジストパターン２３を形成する。つまり、１枚の多階調フォトマスク１０を用いて、被転写体２０上に、レジスト残膜値の異なる９つの転写パターンを転写することができる。なお、ネガ型フォトレジストを用いた場合には、レジスト膜厚が上記と逆転することを考慮した設計を行うことができる。   When the pattern transfer to the transfer target 20 is performed using the multi-tone photomask 10 as described above, the exposure light is not substantially transmitted through the light shielding unit 11 and the exposure light is transmitted through the light transmitting unit 12. And the exposure light is reduced in the first to sixth semi-transparent portions 13A to 13F according to the respective light transmittances. Therefore, the resist film (here, positive photoresist film) applied on the transfer target 20 has the largest thickness in the portion corresponding to the light-shielding portion 11 when developed after pattern transfer. Moreover, in the part corresponding to the said 1st-6th semi-transparent part 13A-13F, although all become thinner than the film thickness of the part corresponding to the light-shielding part 11, according to the light transmittance of each semi-transparent part. The film thickness gradually decreases. Further, there is no film in the portion corresponding to the light transmitting portion 12. As a result, in the photomask 10 of the present embodiment, resist patterns 23 having different film thicknesses in nine stages (one of which has no film) are formed. That is, nine transfer patterns having different resist residual film values can be transferred onto the transfer target 20 using a single multi-tone photomask 10. In the case where a negative photoresist is used, it is possible to design in consideration of the reverse of the resist film thickness.

そして、図１に示す膜厚が９段階に異なるレジストパターン２３を用いて、被転写体２０における積層膜２２の各膜に順次エッチングを実施することにより、例えばＴＦＴ基板の製造における従来のフォトマスク８枚分の工程が実施されることになり、従来よりもマスク枚数を大幅に削減することが可能になる。
以上は、本実施の形態の多階調フォトマスク１０を例えば純粋に９階調のフォトマスクとして使用した場合を説明したが、これには限らず、フォトマスクの構成をたとえば９階調としても、以下のように実効的には３階調を超える３〜８階調のフォトマスクとしても使用することが可能であるという利点がある。 Then, by using the resist patterns 23 having different thicknesses shown in FIG. 1 to sequentially etch each film of the laminated film 22 in the transfer target 20, for example, a conventional photomask for manufacturing a TFT substrate. The process for eight sheets will be performed, and the number of masks can be greatly reduced as compared with the prior art.
The above has described the case where the multi-tone photomask 10 of the present embodiment is used as, for example, a purely nine-tone photomask. However, the present invention is not limited to this. As described below, there is an advantage that it can be effectively used as a photomask having 3 to 8 gradations exceeding 3 gradations.

一般に、本発明の属する多階調フォトマスク（遮光部、透光部のほかに半透光部を有する３階調以上のフォトマスク）においては、被転写体上に所望の残膜値をもつレジストパターンを得るために、半透光部の露光光透過率を選択し、決定する。この透過率としては、透光部（すなわち透明基板が露出している部分）の透過率を１００％としたときの、半透過膜の透過率を用いて規定する。これは、一定以上の広い領域のパターンについて、その透過率を特定する場合には問題がないが、ある程度以下の寸法のパターンに対しては、厳密にいうと、実際のパターン転写に寄与する露光光量を正確に反映していないこととなる。これは露光光の回折が原因であるため、この傾向は微小なパターンになるほど、露光光波長が長いほど顕著になる。しかし、パターンの寸法や、分光特性の異なる光源に対する透過率の変化については正確に考慮されていないのが現状である。   In general, a multi-tone photomask to which the present invention belongs (a photomask having three or more tones having a semi-transparent portion in addition to a light-shielding portion and a light-transmitting portion) has a desired remaining film value on a transfer target. In order to obtain a resist pattern, the exposure light transmittance of the semi-translucent portion is selected and determined. The transmittance is defined using the transmittance of the semi-transmissive film when the transmittance of the light transmitting portion (that is, the portion where the transparent substrate is exposed) is 100%. This is not a problem when specifying the transmittance of a pattern of a wide area above a certain level, but strictly speaking, for a pattern with a size of a certain degree or less, exposure that contributes to actual pattern transfer. The amount of light is not accurately reflected. Since this is due to diffraction of exposure light, this tendency becomes more prominent as the exposure light wavelength becomes longer as the pattern becomes smaller. However, the present situation is that the change in transmittance with respect to light sources having different pattern dimensions and spectral characteristics is not accurately taken into consideration.

具体的には、半透光部に、非常に狭い幅を含むパターン形状と、相対的に広い領域のパターン形状とが存在すると、半透光部には、被転写体上のレジスト膜に、常に一定の残膜値を与えるものであるべきところ、パターン形状に起因して異なる残膜値のレジストパターンが形成されてしまい、所望の許容範囲を越えた残膜値のばらつきを生じると、電子デバイス製造上の不安定要素となるという問題がある。   Specifically, when a pattern shape including a very narrow width and a pattern shape of a relatively wide region are present in the semi-transparent portion, the semi-transparent portion has a resist film on the transfer target, Where a constant residual film value should always be given, a resist pattern with a different residual film value is formed due to the pattern shape, and if the residual film value varies beyond the desired tolerance, There is a problem that it becomes an unstable factor in device manufacturing.

例えば、薄膜トランジスタ用の多階調フォトマスクとしては、チャネル部に相当する領域を半透光部とし、これを挟む形で隣接するソース及びドレインに相当する領域を遮光部で構成したものが多用される。このフォトマスクは、通常i線〜ｇ線の波長帯の露光光を用いて露光されるが、チャネル部の寸法（幅）が小さくなるにしたがい、隣接する遮光部との境界が、実際の露光条件下においてぼかされ、チャネル部の露光光透過率は半透過膜の透過率よりも低くなる。図６は、遮光部Ａに挟まれた半透光部Ｂのパターン（同図（１））と、該半透光部Ｂの透過光の光強度分布（同図（２））を示したもので、同図（ａ）は一例として半透光領域の幅が４μｍ、同図（ｂ）は２μｍの場合をそれぞれ示している。すなわち、図６（ａ），（ｂ）に示すように、遮光部Ａに挟まれた半透光部Ｂの透過光の光強度分布は、その半透光部Ｂの線幅が小さくなると、全体に下がり、ピークが低くなる。つまり、幅が狭い領域を有するパターンについては、実際に露光に寄与する透過率が相対的に低い一方、相対的に線幅が広い領域を有するパターンについては、実際の露光に寄与する透過率が相対的に高い。例えば、図７に示すように、チャネル幅が５μｍ以下では、該チャネル幅に対応した幅の半透光部における、実際の露光に寄与する光の透過率が低下する。   For example, a multi-tone photomask for a thin film transistor is often used in which a region corresponding to a channel portion is a semi-translucent portion and a region corresponding to a source and a drain adjacent to each other is formed by a light shielding portion. The This photomask is normally exposed using exposure light in the wavelength band of i-line to g-line, but as the size (width) of the channel portion becomes smaller, the boundary with the adjacent light-shielding portion is the actual exposure. The exposure light transmittance of the channel portion is lower than the transmittance of the semi-transmissive film. FIG. 6 shows the pattern of the semi-transparent part B sandwiched between the light-shielding parts A (FIG. 1 (1)) and the light intensity distribution of the transmitted light of the semi-transparent part B (FIG. 2). FIG. 6A shows the case where the width of the semi-translucent region is 4 μm as an example, and FIG. 6B shows the case where the width is 2 μm. That is, as shown in FIGS. 6A and 6B, the light intensity distribution of the transmitted light of the semi-transparent part B sandwiched between the light-shielding parts A is as follows. The whole is lowered and the peak is lowered. In other words, the transmittance that actually contributes to the exposure is relatively low for the pattern having the narrow width region, while the transmittance that contributes to the actual exposure is the pattern that has the relatively wide line width. Relatively high. For example, as shown in FIG. 7, when the channel width is 5 μm or less, the transmissivity of light contributing to actual exposure in the semi-transparent portion having a width corresponding to the channel width decreases.

そこで、一定の寸法をもつ半透光部の透過率を、その膜固有の透過率と区別し、実際の露光光の透過量を、透光部の透過量との比において、実効透過率として把握する必要が生じる。
一方で、膜固有の透過率とは、透明基板上の該膜を形成した、十分に広い領域において、該膜の組成や膜厚によって決定されるものである。十分に広い領域とは、該領域の広さの変化によって、実効透過率が実質的に変化しないような領域をいう。なお、図７においては、半透光部Ｂの透過光の光強度分布のピーク値によって、該領域の透過率を代表させている。この部分の透過率は、この多階調マスクを使用して露光したときの、被転写体上のレジスト残膜値と相関をもつ。 Therefore, the transmissivity of the semi-transparent part having a certain size is distinguished from the transmissivity inherent to the film, and the actual amount of exposure light transmission is determined as the effective transmissivity in the ratio of the transmissivity of the translucent part. It is necessary to grasp.
On the other hand, the transmittance specific to the film is determined by the composition and film thickness of the film in a sufficiently wide region where the film is formed on the transparent substrate. A sufficiently wide region refers to a region where the effective transmittance does not substantially change due to a change in the size of the region. In FIG. 7, the transmittance of the region is represented by the peak value of the light intensity distribution of the transmitted light of the semi-translucent portion B. The transmittance of this portion has a correlation with the resist residual film value on the transfer target when the multi-tone mask is used for exposure.

そこで、半透光部のパターン形状に応じて、その部分の膜構成や微細パターンを選択し、それによって光透過率を変えることにより、パターン形状にかかわらず、半透光部の実効透過率をほぼ均一とし、結果的に該マスクを用いてパターン転写を行う際の、被転写体上のレジスト膜の残膜値をほぼ同一にできることとなる。
例えば、本実施の形態によれば、マスク構成として、４つ乃至９つの階調を有する多階調フォトマスクを得ることができる。すなわち、透光部、遮光部のほかに、２つ乃至７つの異なる光透過率を有する半透光部を得ることができるのである。この例えば７種類の半透光部によって、被転写体上に、それぞれ異なるレジスト残膜値をもつレジストパターンを形成してもよい。しかしながら、他方、この例えば７種類の半透光部によって、被転写体上に、パターンの寸法が異なる（従って、同一の光透過率を有する半透光部を使用すると、形成されるレジスト残膜値が異なってしまう）にもかかわらず、実効透過率をほぼ均一にし、被転写体上に一定のレジスト残膜値を有するレジストパターンを形成することができる。換言すれば、上記半透光部１３Ａから１３Ｆはそれぞれ、半透光膜により形成された部分、半透光膜の微細パターンと遮光膜の微細パターンの組合せにより形成された部分、半透光膜の微細パターンにより形成された部分、及び遮光膜の微細パターンにより形成された部分のいずれかから構成され、半透光部のパターン形状に応じて異なる例えば７種類の光透過率を有するが、パターン転写の結果ほぼ同一の実効透過率を有するような半透光部を形成しても良い。この場合、本実施の形態のフォトマスクを３階調のフォトマスクとして用いることになる。 Therefore, depending on the pattern shape of the semi-transparent part, the film configuration and fine pattern of that part are selected, and the light transmittance is changed accordingly, so that the effective transmittance of the semi-transparent part can be increased regardless of the pattern shape. As a result, the residual film value of the resist film on the transfer target can be made substantially the same when pattern transfer is performed using the mask.
For example, according to the present embodiment, a multi-tone photomask having 4 to 9 gradations can be obtained as a mask configuration. That is, in addition to the light-transmitting portion and the light-shielding portion, a semi-light-transmitting portion having two to seven different light transmittances can be obtained. For example, resist patterns having different resist residual film values may be formed on the transfer object by using seven types of semi-transparent portions. However, on the other hand, for example, the seven types of semi-transparent portions have different pattern dimensions on the transfer target (therefore, the remaining resist film formed when the semi-transparent portions having the same light transmittance are used. Despite the difference in value, the effective transmittance can be made substantially uniform, and a resist pattern having a certain resist residual film value can be formed on the transfer target. In other words, the semi-transparent portions 13A to 13F are respectively a part formed by a semi-transparent film, a part formed by a combination of a fine pattern of the semi-transparent film and a fine pattern of the light shielding film, and a semi-transparent film. For example, there are seven different light transmittances depending on the pattern shape of the semi-translucent portion. A semi-transparent portion having substantially the same effective transmittance as a result of the transfer may be formed. In this case, the photomask of this embodiment is used as a three-tone photomask.

もちろん、半透光部１３Ａから１３Ｆのうち、例えば半透光部１３Ａと１３Ｂ、あるいはこれらを含む複数の半透光部を、同一の実効透過率を有する異なる形状のパターンに用い、残りの半透光部を、異なる実効透過率を有するパターンに供しても良い。この場合、本実施の形態のフォトマスクを４階調〜８階調のフォトマスクとして用いることになる。   Of course, among the semi-transparent portions 13A to 13F, for example, the semi-transparent portions 13A and 13B or a plurality of semi-transparent portions including these are used for patterns of different shapes having the same effective transmittance, and the remaining semi-transparent portions are used. The translucent part may be provided for patterns having different effective transmittances. In this case, the photomask of this embodiment is used as a photomask having 4 to 8 gradations.

以上のように、本実施の形態の多階調フォトマスク１０は、例えば９つの異なる光透過率をもたせることができるので、純粋に９階調フォトマスクとして使用することができるが、これに限定されず、例えば半透光部のパターン形状にかかわらず、ほぼ同一の残膜値のレジストパターンを形成する場合に、３階調乃至８階調のフォトマスクとして使用することが可能である。しかも、本実施の形態では、半透光部１３Ａから１３Ｆはそれぞれ、半透光膜により形成された部分、半透光膜の微細パターンと遮光膜の微細パターンの組合せにより形成された部分、半透光膜の微細パターンにより形成された部分、及び遮光膜の微細パターンにより形成された部分のいずれかから構成されるので、たとえば半透光部１３Ｂは、半透光部１３Ａと同じ半透光膜を用いた微細パターンと、遮光部１１と同じ遮光膜を用いた微細パターンを透明基板上に形成することにより簡便に得ることができる。また、半透光部１３Ｃ（半透光部１３Ｄも同様）は、透明基板上の半透光膜１６の上に遮光部１１と同じ遮光膜を用いて微細パターンを形成することにより簡便に得ることができる。さらに、半透光部１３Ｅは、半透光部１３Ａと同じ半透光膜を用いた微細パターンを形成することにより、また半透光部１３Ｆは、遮光部１１と同じ遮光膜を用いて微細パターンを形成することにより簡便に得ることができる。たとえば半透光膜の材質や膜厚の変更によって３種類以上の半透光部を形成する場合と比べると、本発明では、半透光部の透過率を調節できる範囲、精度が大きく、膜構成が単純で、製造上のメリットも大きい。したがって、本実施の形態の多階調フォトマスクは、実効的に例えば９階調のフォトマスクとして使用する場合はもちろんのこと、実効的に３階調乃至８階調のフォトマスクとして使用する場合にも好適である。   As described above, since the multi-tone photomask 10 of the present embodiment can have, for example, nine different light transmittances, it can be used purely as a nine-tone photomask, but is not limited thereto. However, for example, when a resist pattern having substantially the same remaining film value is formed regardless of the pattern shape of the semi-translucent portion, it can be used as a photomask of 3 to 8 gradations. Moreover, in the present embodiment, the semi-transparent portions 13A to 13F are each a portion formed by a semi-transparent film, a portion formed by a combination of a fine pattern of the semi-transparent film and a fine pattern of the light-shielding film, For example, the semi-transparent portion 13B is the same as the semi-transparent portion 13A because the semi-transparent portion 13B is composed of either the portion formed by the fine pattern of the translucent film or the portion formed by the fine pattern of the light-shielding film. A fine pattern using a film and a fine pattern using the same light-shielding film as the light-shielding part 11 can be easily obtained by forming them on a transparent substrate. Further, the semi-transparent portion 13C (the same applies to the semi-transparent portion 13D) can be easily obtained by forming a fine pattern on the semi-transparent film 16 on the transparent substrate using the same light-shielding film as the light-shielding portion 11. be able to. Further, the semi-transparent portion 13E is formed by forming a fine pattern using the same semi-transparent film as the semi-transparent portion 13A, and the semi-transparent portion 13F is finely formed using the same light-shielding film as the light-shielding portion 11. It can be easily obtained by forming a pattern. For example, in comparison with the case where three or more kinds of semi-transparent portions are formed by changing the material and film thickness of the semi-transparent film, the present invention has a greater range and accuracy in which the transmittance of the semi-transparent portion can be adjusted. The structure is simple and there are great manufacturing advantages. Therefore, the multi-tone photomask of this embodiment is effectively used as, for example, a nine-tone photomask, as well as a three- to eight-tone photomask. Also suitable.

なお、上記では、遮光部１１と透光部１２のほかに、半透光部１３Ａ〜１３Ｆを有するフォトマスクを示したが、本発明はこれには限定されず、遮光部１１と透光部１２のほかに、半透光部１３Ａ〜１３Ｆのうちから任意に選択された半透光部を有するフォトマスク、例えば、遮光部１１と透光部１２のほかに、半透光膜１６によりなる半透光部１３Ａと、半透光膜１６の微細パターン、半透光膜１６と遮光膜１５の積層膜の微細パターン及びこれらの微細パターン間の微細隙間（スペース部分）によりなる半透光部１３Ｂとを有するフォトマスク、あるいは、遮光部１１と透光部１２のほかに、上記半透光部１３Ａと半透光部１３Ｂと、上記半透光膜１６と遮光膜１５の積層膜の微細パターン１８と該微細パターン１８間に形成された上記半透光膜１６の微細パターンによりなる半透光部１３Ｃを有するフォトマスクとしてもよい。この場合、実効的に５階調乃至３階調のフォトマスクとして用いることができる。   In the above description, the photomask having the semi-transparent portions 13A to 13F in addition to the light shielding portion 11 and the light transmitting portion 12 is shown. However, the present invention is not limited to this, and the light shielding portion 11 and the light transmitting portion are provided. 12, a photomask having a semitransparent portion arbitrarily selected from the semitransparent portions 13 </ b> A to 13 </ b> F, for example, a semitransparent film 16 in addition to the light shielding portion 11 and the translucent portion 12. Semi-translucent portion composed of semi-transparent portion 13A, micro-pattern of semi-transparent film 16, micro-pattern of laminated film of semi-transparent film 16 and light-shielding film 15, and micro-gap (space portion) between these micro-patterns In addition to the photomask having 13B, or the light-shielding portion 11 and the light-transmitting portion 12, in addition to the semi-light-transmitting portion 13A, the semi-light-transmitting portion 13B, the laminated film of the semi-light-transmitting film 16 and the light-shielding film 15 The above-mentioned formed between the pattern 18 and the fine pattern 18 Or as a photo mask having a semi-transparent portion 13C made by fine pattern translucent film 16. In this case, it can be effectively used as a photomask having 5 to 3 gradations.

次に、上記の本実施の形態に係る多階調フォトマスク１０の製造方法について説明する。図２は、上記第１の実施の形態の多階調フォトマスク１０の製造工程を工程順に示す断面図である。
使用するフォトマスクブランクは、図２（ａ）に示すように、ガラス基板等の透明基板１４上に、半透光膜１６と、遮光層１５ａ及び反射防止層１５ｂの積層からなる遮光膜１５が順に形成されている。ただし、上記半透光膜１６と上記遮光膜１５は、エッチング工程に用いるエッチャントに対するエッチング選択性のある材質の組み合わせが選択される。したがって、上記遮光層１５ａとしては、例えばクロム又はその化合物（例えばＣｒＮ，ＣｒＯ，ＣｒＣ等）が好ましく挙げられ、上記反射防止層１５ｂとしては、クロム系化合物（例えばＣｒＮ，ＣｒＯ，ＣｒＣ等）などが挙げられる。ここでは、Ｃｒの遮光層、ＣｒＯの反射防止層を用いた。さらに上記半透光膜１６としては、例えば金属シリサイド、特にモリブデンシリサイド化合物（MoSixのほか、MoSiの窒化物、酸化物、酸化窒化物、炭化物など）等が好ましく挙げられる。上記半透光膜１６は、透明基板１４（透光部）の露光光の透過量に対し１０〜８０％程度、好ましくは２０〜７０％程度の透過量を有するものが好ましい。ここでは、膜透過率４０％（透光部を１００％としたとき）のＭｏＳｉｘ膜を用いた。 Next, a method for manufacturing the multi-tone photomask 10 according to the present embodiment will be described. FIG. 2 is a cross-sectional view showing the manufacturing steps of the multi-tone photomask 10 of the first embodiment in the order of steps.
As shown in FIG. 2A, the photomask blank to be used includes a semi-transparent film 16 and a light shielding film 15 made of a laminate of a light shielding layer 15a and an antireflection layer 15b on a transparent substrate 14 such as a glass substrate. It is formed in order. However, the semi-transparent film 16 and the light shielding film 15 are selected from a combination of materials having etching selectivity with respect to the etchant used in the etching process. Therefore, as the light shielding layer 15a, for example, chromium or a compound thereof (for example, CrN, CrO, CrC, etc.) is preferably mentioned, and as the antireflection layer 15b, a chromium compound (for example, CrN, CrO, CrC, etc.) or the like is preferable. Can be mentioned. Here, a Cr light shielding layer and a CrO antireflection layer were used. Further, as the semi-transparent film 16, for example, metal silicide, in particular, molybdenum silicide compound (MoSix, MoSi nitride, oxide, oxynitride, carbide, etc.) is preferable. The semi-transparent film 16 preferably has a transmission amount of about 10 to 80%, preferably about 20 to 70% with respect to the transmission amount of exposure light of the transparent substrate 14 (translucent portion). Here, a MoSix film having a film transmittance of 40% (when the light transmitting portion is 100%) was used.

まず、上記フォトマスクブランク上にレジストを塗布してレジスト膜を形成し、１度目の描画を行う。本実施の形態では例えばレーザー光を用いる。また、上記レジストとしてはポジ型フォトレジストを使用する。そして、レジスト膜に対し、所定のパターンを描画し、描画後に現像を行うことにより、第１レジストパターン３０ａ〜３０ｃを形成する（図２（ｂ）参照）。該第１レジストパターン３０ａ、３０ｃは、製造されるフォトマスクの遮光部１１、第１半透光部１３Ａ、第３半透光部１３Ｃ及び第６半透光部１３Ｄの領域を覆い、第１レジストパターン３０ｂは、第２半透光部１３Ｂ、及び第４、第５半透光部１３Ｅ，１３Ｆの領域に所定の微細パターンを形成するためのレジストパターンを含む。   First, a resist is applied on the photomask blank to form a resist film, and a first drawing is performed. In this embodiment, for example, laser light is used. A positive photoresist is used as the resist. Then, a predetermined pattern is drawn on the resist film, and development is performed after the drawing, thereby forming first resist patterns 30a to 30c (see FIG. 2B). The first resist patterns 30a and 30c cover the regions of the light shielding part 11, the first semi-transparent part 13A, the third semi-transparent part 13C, and the sixth semi-transparent part 13D of the photomask to be manufactured, The resist pattern 30b includes a resist pattern for forming a predetermined fine pattern in the regions of the second semi-transparent portion 13B and the fourth and fifth semi-transparent portions 13E and 13F.

なお、フォトマスクの第２半透光部１３Ｂを構成する上記半透光膜１６の微細パターン及び上記半透光膜１６と上記遮光膜１５の積層膜の微細パターン、第３半透光部１３Ｃ及び第６半透光部１３Ｄを構成する上記半透光膜１６と遮光膜１５の積層膜の微細パターン１８と該微細パターン１８間に形成された上記半透光膜１６の微細パターン、第４半透光部１３Ｅを構成する上記半透光膜１６の微細パターン、および第５半透光部１３Ｆを構成する上記半透光膜１６と上記遮光膜１５の積層膜の微細パターンはいずれもフォトマスクを使用する露光条件下で解像限界以下の微細パターンであり、かつ第１半透光部１３Ａの露光光透過率が所望の値となるように、上記半透光膜の膜透過率（膜としての固有の透過率、すなわち、膜素材と膜厚による）を設定するとともに、第２〜第６半透光部１３Ｂから１３Ｆのそれぞれの露光光透過率が所望の値となるように上記微細パターンのそれぞれの線幅が設定される。   The fine pattern of the semi-transparent film 16 and the fine pattern of the laminated film of the semi-transparent film 16 and the light shielding film 15 constituting the second semi-transmissive part 13B of the photomask, and the third semi-transmissive part 13C. And a micropattern 18 of the laminated film of the semitranslucent film 16 and the light shielding film 15 constituting the sixth semitransparent portion 13D, and a micropattern of the semitranslucent film 16 formed between the micropatterns, a fourth The fine pattern of the semi-transparent film 16 constituting the semi-transparent part 13E and the fine pattern of the laminated film of the semi-transparent film 16 and the light shielding film 15 constituting the fifth semi-transparent part 13F are both photo The film transmissivity of the semi-transparent film (the transmissivity of the semi-transparent film so that the exposure light transmissivity of the first semi-translucent portion 13A becomes a desired value under the exposure conditions using a mask and having a fine pattern below the resolution limit. Inherent transmittance as a membrane, i.e., membrane material and film thickness That) sets a, the line widths of the fine pattern so that each of the exposure light transmittance of 13F from the second to sixth semi-light-transmitting portion 13B becomes a desired value is set.

次に、上記第１レジストパターン３０ａ〜３０ｃをエッチングマスクとして遮光層１５ａ及び反射防止層１５ｂの積層からなる遮光膜１５をエッチングして遮光膜パターンを形成する（図２（ｃ）参照）。クロムを主成分とする遮光膜１５を用いた場合、エッチング手段としては、ドライエッチングもしくはウェットエッチングのどちらでも可能であるが、たとえば大型液晶表示パネル製造に使用する大型サイズのフォトマスクでは、ウェットエッチングが好適である。ウェットエッチングでは、エッチング液として例えば硝酸第二セリウムアンモニウムを用いる。なお、上記遮光膜１５とその下の半透光膜１６は、互いに所定のエッチャントに対するエッチング選択性を有する材質で形成されていることが好ましい。この場合、上記遮光膜１５のエッチング時には上記半透光膜１６はエッチングされにくい。   Next, using the first resist patterns 30a to 30c as an etching mask, the light shielding film 15 formed by stacking the light shielding layer 15a and the antireflection layer 15b is etched to form a light shielding film pattern (see FIG. 2C). When the light shielding film 15 mainly composed of chromium is used, the etching means can be either dry etching or wet etching. For example, in the case of a large-sized photomask used for manufacturing a large liquid crystal display panel, wet etching is used. Is preferred. In wet etching, for example, ceric ammonium nitrate is used as an etchant. The light shielding film 15 and the semi-transparent film 16 below the light shielding film 15 are preferably formed of materials having etching selectivity with respect to a predetermined etchant. In this case, the semi-transparent film 16 is hardly etched when the light shielding film 15 is etched.

残存する第１レジストパターン３０を除去した後（図２（ｄ）参照）（あるいは次の半透光膜１６のエッチング工程終了後に除去してもよい）、上記で形成された遮光膜パターンをマスクとして、下層の半透光膜１６をエッチングする（図２（ｅ）参照）。例えばモリブデンシリサイド化合物を主成分とする半透光膜１６を用いた場合、エッチング手段としては、ドライエッチングもしくはウェットエッチングのどちらでも可能であるが、ウェットエッチングではエッチング液として例えばフッ化水素アンモニウムを主成分とするものを用いる。   After the remaining first resist pattern 30 is removed (see FIG. 2D) (or may be removed after the next semi-transparent film 16 is etched), the light shielding film pattern formed above is masked. Then, the lower semi-transparent film 16 is etched (see FIG. 2E). For example, when the translucent film 16 mainly composed of a molybdenum silicide compound is used, either dry etching or wet etching can be used as an etching means. In wet etching, for example, ammonium hydrogen fluoride is mainly used as an etching solution. Use ingredients.

次に、再び全面に上記と同じレジスト膜を形成し、２度目の描画を行う。すなわち、このレジスト膜に対し、所定のパターンを描画し、描画後に現像を行うことにより、第２レジストパターン３１ａ〜３１ｄを形成する（図２（ｆ）参照）。該第２レジストパターン３１ａと３１ｂは、製造されるフォトマスクの遮光部１１の領域を覆うとともに、上記半透光膜１６と上記遮光膜１５の積層膜の微細パターンが形成された第５半透光部１３Ｆの領域を覆うように形成される。また、第２レジストパターン３１ｃは、製造されるフォトマスクの第２半透光部１３Ｂの領域に形成された微細パターンのうち最終的に半透光膜１６と遮光膜１５の積層膜の微細パターンを形成する微細パターンとその両側の微細隙間（スペース領域）を覆うように形成され、３１ｄは、第３半透光部１３Ｃと第６半透光部１３Ｄの領域に所定の微細パターンを形成するためのレジストパターンである。   Next, the same resist film as described above is formed again on the entire surface, and a second drawing is performed. That is, a predetermined pattern is drawn on the resist film, and development is performed after the drawing, thereby forming second resist patterns 31a to 31d (see FIG. 2F). The second resist patterns 31a and 31b cover the region of the light-shielding portion 11 of the photomask to be manufactured, and the fifth semi-transparent film in which the fine pattern of the laminated film of the semi-transmissive film 16 and the light-shielding film 15 is formed. It is formed so as to cover the region of the optical part 13F. The second resist pattern 31c is a fine pattern of a laminated film of the semi-transparent film 16 and the light shielding film 15 among the fine patterns formed in the region of the second semi-transmissive part 13B of the photomask to be manufactured. Is formed so as to cover the fine patterns forming the gaps and the fine gaps (space areas) on both sides thereof, and 31d forms a predetermined fine pattern in the areas of the third semi-transmissive part 13C and the sixth semi-transmissive part 13D. This is a resist pattern.

なおここで、半透光膜１６と遮光膜１５の積層膜の微細パターンが形成された第５半透光部１３Ｆの領域を覆う第２レジストパターン３１ｂを該領域幅よりも幅広に形成することが好適である（図２（ｆ）中の符号３１ｅにより示す部分を参照）。これによって、第２レジストパターンを形成するための２度目の描画時に仮に１度面の描画パターンに対するアライメントずれが発生した場合に、そのアライメントずれの影響を防止でき、微細パターンのＣＤ精度が良好に維持される。従って、半透光部１３Ｆの透過率が許容範囲を超えてずれてしまうことが防止できる。なお、ここで、第２レジストパターン３１ｂのパターンデータを加工することによって、上記した幅広のレジストパターンを形成するが、このときにサイズ拡大するマージン幅の決定に際しては、想定されるアライメントずれ量を加算したときに、上記積層膜の微細パターンが、整数個確実に包含されるような、レジストパターン幅とすることが好ましい。同様のアライメントずれ対策は、他の態様においても用いることができる。   Here, the second resist pattern 31b covering the region of the fifth semi-transparent portion 13F in which the fine pattern of the laminated film of the semi-transparent film 16 and the light shielding film 15 is formed is formed wider than the region width. (Refer to the portion indicated by reference numeral 31e in FIG. 2 (f)). As a result, if a misalignment with respect to the drawing pattern on the first surface occurs at the time of the second drawing for forming the second resist pattern, the influence of the misalignment can be prevented and the CD accuracy of the fine pattern can be improved. Maintained. Accordingly, it is possible to prevent the transmissivity of the semi-translucent portion 13F from deviating beyond an allowable range. Here, by processing the pattern data of the second resist pattern 31b, the above-described wide resist pattern is formed. In determining the margin width to be enlarged at this time, an assumed misalignment amount is set. It is preferable that the resist pattern width be such that when added, an integer number of fine patterns of the laminated film are surely included. Similar countermeasures against misalignment can be used in other embodiments.

次に、上記第２レジストパターン３１ａ〜３１ｄをマスクとして、露出した領域上の遮光膜１５及び遮光膜１５の微細パターンを同時にエッチングする（図２（ｇ）参照）。この場合のエッチング条件は、上述の（ｃ）工程と同様でよい。この遮光膜１５のエッチング条件に対してその下の半透光膜１６はエッチング選択性を有するため、上記半透光膜１６はエッチングされにくい。   Next, using the second resist patterns 31a to 31d as a mask, the light shielding film 15 and the fine pattern of the light shielding film 15 on the exposed region are simultaneously etched (see FIG. 2G). The etching conditions in this case may be the same as the above-described step (c). The semi-transparent film 16 under the light-shielding film 15 has etching selectivity with respect to the etching conditions of the light-shielding film 15, so that the semi-transparent film 16 is hardly etched.

そして、残存する第２レジストパターン３１ａ〜３１ｄを除去する。こうして、透明基板１４上に、半透光膜１６と、遮光層１５ａ及び反射防止層１５ｂからなる遮光膜１５との積層によりなる遮光部１１、透明基板１４が露出する透光部１２、及び、上記半透光膜１６によりなる第１半透光部１３Ａと、上記と同じ半透光膜１６の微細パターン１７と、上記遮光部と同じ半透光膜１６と遮光膜１５の積層膜の微細パターン１８と、微細隙間（スペース部分）とからなる露光条件下における解像限界以下の線幅をもつ微細パターンによりなる第２半透光部１３Ｂと、上記半透光膜１６と遮光膜１５の積層膜の微細パターン１８と、該微細パターン１８間に形成された上記半透光膜１６の微細パターンとからなる露光条件下における解像限界以下の線幅をもつ微細パターンによりなる第３半透光部１３Ｃと、上記と同じ半透光膜１６で形成された露光条件下において解像限界以下の微細パターン１７によりなる第４半透光部１３Ｅと、上記遮光部と同じ半透光膜１６及び遮光膜１５の積層膜で形成された露光条件下において解像限界以下の微細パターン１８によりなる第５半透光部１３Ｆと、上記第３半透光部１３Ｃにおける半透光膜１６で形成された微細パターンの線幅と遮光膜１５で形成された微細パターン１８の線幅が異なる幅に形成された第６半透光部１３Ｄを有するマスクパターンが形成された、露光光透過率が例えば９段階に異なる９階調のフォトマスク１０が出来上がる（図２（ｈ）参照）。ここで、例えば第２半透光部１３Ｂ〜第５半透光部１３Ｆにおいても、微細パターンの線幅を領域によって変更すれば、更に、多階調のフォトマスクを製造することも可能である。その場合、製造プロセスは上記のままで行うことができる。   Then, the remaining second resist patterns 31a to 31d are removed. Thus, on the transparent substrate 14, the light-shielding portion 11 formed by stacking the light-transmitting film 16 and the light-shielding film 15 including the light-shielding layer 15a and the antireflection layer 15b, the light-transmitting portion 12 from which the transparent substrate 14 is exposed, and The first semi-transparent portion 13A formed of the semi-transparent film 16, the fine pattern 17 of the same semi-transparent film 16 as described above, and the fine film of the laminated film of the same semi-transparent film 16 and light-shield film 15 as the light-shielding portion. A second semi-transparent portion 13B made of a fine pattern having a line width less than the resolution limit under exposure conditions comprising a pattern 18 and fine gaps (space portions); and the semi-transparent film 16 and the light-shielding film 15 A third semi-transparent film comprising a fine pattern 18 having a line width equal to or smaller than the resolution limit under an exposure condition comprising the fine pattern 18 of the laminated film and the fine pattern of the semi-transmissive film 16 formed between the fine patterns 18. Optical part 13C and the above A fourth semi-transparent portion 13E having a fine pattern 17 below the resolution limit under the exposure conditions formed by the same semi-transparent film 16, and a laminated film of the same semi-transparent film 16 and light-shielding film 15 as the light-shielding portion The line width of the fine pattern formed by the semi-transparent film 13 in the fifth semi-transparent portion 13F and the third semi-transparent portion 13C formed by the fine pattern 18 below the resolution limit under the exposure conditions formed in FIG. The mask pattern having the sixth semi-transparent portion 13D formed with different widths of the fine pattern 18 formed of the light shielding film 15 and the light shielding film 15 is formed. The photomask 10 is completed (see FIG. 2H). Here, for example, also in the second semi-transparent part 13B to the fifth semi-transparent part 13F, it is possible to manufacture a multi-tone photomask by changing the line width of the fine pattern depending on the region. . In that case, the manufacturing process can be carried out as described above.

以上のように本実施の形態の多階調フォトマスクの製造方法によれば、遮光膜と半透光膜との組み合わせを用い、フォトリソグラフィ法によって、半透光膜によりなる半透光部と、半透光膜の微細パターン及び／又は遮光膜の微細パターンによりそれぞれなる半透光部を一緒に精度良く形成することができ、上記多階調フォトマスクを効率的で、かつ欠陥発生の確率の低い簡便な工程によって製造することができるので、量産上のメリットが大きい。
また、前述の図１に示すような本発明に係る多階調フォトマスクを用いたパターン転写を実施すると、被転写体には所望のレジスト残膜値を有する、精度の高い多階調の転写パターンを形成することができる。
なお、上記において、遮光膜１５と半透光膜１６には、互いにエッチング選択性のある膜を用いた。一方、遮光膜１５と半透光膜１６に十分なエッチング選択性が無い場合には、両者の間にエッチングストッパ膜を導入することも可能である。この場合、遮光膜１５、及び半透光膜１６をともに、クロム又はクロム化合物からなる膜とし、エッチングストッパ膜に、モリブデンシリサイドや二酸化ケイ素などを用いることが可能である。 As described above, according to the method for manufacturing a multi-tone photomask of the present embodiment, a combination of a light-shielding film and a semi-transparent film is used, and a semi-transparent portion made of a semi-transparent film is formed by photolithography. The semi-transparent portion can be formed with high accuracy by the micro-pattern of the semi-transparent film and / or the micro-pattern of the light-shielding film, and the multi-tone photomask can be formed efficiently and the probability of defect occurrence. Since it can be manufactured by a simple and low process, the merit in mass production is great.
In addition, when pattern transfer using the multi-tone photomask according to the present invention as shown in FIG. 1 is performed, high-precision multi-tone transfer having a desired resist residual film value on the transfer target is performed. A pattern can be formed.
In the above description, the light shielding film 15 and the semi-transparent film 16 are films having etching selectivity with each other. On the other hand, if the light shielding film 15 and the semi-transparent film 16 do not have sufficient etching selectivity, an etching stopper film can be introduced between them. In this case, both the light shielding film 15 and the semi-transparent film 16 can be made of chromium or a chromium compound, and molybdenum silicide, silicon dioxide, or the like can be used for the etching stopper film.

なお、図２に示す本発明の多階調マスクは、その製造工程を変更し、図３のように製造することも可能である。ここでは、前述の図２において、第1レジストパターン（又はそれをマスクとしてエッチングした遮光膜パターン）をマスクとして半透光膜をエッチングしたのに対し、遮光膜のみをエッチングする。更に、第２レジストパターンをマスクとして、遮光膜をエッチングするかわりに、半透光膜をエッチングする点が相違している。
なお、ここで、第２レジストパターンは、少なくとも遮光部の一部分を含むことが好ましいが、より好ましくは、図３のように、透光部に隣接する遮光部には、第２レジストパターンに含まれない部分があることが好ましい。このようにすると、微細パターンにおけるアライメントずれや、遮光膜のダメージの影響が抑止される。 The multi-tone mask of the present invention shown in FIG. 2 can be manufactured as shown in FIG. 3 by changing the manufacturing process. Here, in FIG. 2 described above, the semi-transparent film is etched using the first resist pattern (or the light shielding film pattern etched using the first resist pattern as a mask), whereas only the light shielding film is etched. Another difference is that the semi-transparent film is etched instead of etching the light shielding film using the second resist pattern as a mask.
Here, the second resist pattern preferably includes at least a part of the light shielding part, but more preferably, the light shielding part adjacent to the light transmitting part is included in the second resist pattern as shown in FIG. It is preferable that there is a portion that is not. In this way, the effects of misalignment in the fine pattern and damage to the light shielding film are suppressed.

［第２の実施の形態］
次に、図４に従って本発明の第２の実施の形態を説明する。図４は第２の実施の形態に係る多階調フォトマスク１０の製造工程を工程順に示す断面図である。なお、前述の第１の実施の形態を示す図１及び図２と同等の箇所には同一の符号を付している。
使用するフォトマスクブランクは、図４（ａ）に示すように、ガラス基板等の透明基板１４上に、遮光層１５ａ及び反射防止層１５ｂの積層からなる遮光膜１５が形成されている。上記遮光層１５ａとしては、例えばクロム又はその化合物（例えばＣｒＮ，ＣｒＯ，ＣｒＣ等）が好ましく挙げられ、上記反射防止層１５ｂとしては、クロム系化合物（例えばＣｒＮ，ＣｒＯ，ＣｒＣ等）などが挙げられる。 [Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 4 is a cross-sectional view showing the manufacturing steps of the multi-tone photomask 10 according to the second embodiment in the order of steps. In addition, the same code | symbol is attached | subjected to the location equivalent to FIG.1 and FIG.2 which shows the above-mentioned 1st Embodiment.
As shown in FIG. 4A, the photomask blank to be used has a light shielding film 15 formed of a laminate of a light shielding layer 15a and an antireflection layer 15b on a transparent substrate 14 such as a glass substrate. As the light shielding layer 15a, for example, chromium or a compound thereof (for example, CrN, CrO, CrC, etc.) is preferably mentioned, and as the antireflection layer 15b, a chromium compound (for example, CrN, CrO, CrC, etc.) can be mentioned. .

まず、上記フォトマスクブランク上にレジストを塗布してレジスト膜を形成し、１度目の描画を行う。上記レジストとしてはポジ型フォトレジストを使用する。そして、レジスト膜に対し、所定のパターンを描画し、描画後に現像を行うことにより、第１レジストパターン３２ａ〜３２ｄを形成する（図４（ｂ）参照）。
該第１レジストパターン３２ａは、製造されるフォトマスクの遮光部１１、透光部１２、及び第５半透光部１３Ｆの領域を覆い、第１レジストパターン３２ｂは、第４半透光部１３Ｅの領域に所定の微細パターンを形成するためのレジストパターンである。また、第１レジストパターン３２ｃは、第２半透光部１３Ｂの領域に半透光膜の微細パターンを形成するためのレジストパターンであり、また３２ｄは、第３、第６半透光部１３Ｃ，１３Ｄの領域に半透光膜の微細パターンを形成するためのレジストパターンである。 First, a resist is applied on the photomask blank to form a resist film, and a first drawing is performed. A positive photoresist is used as the resist. Then, a predetermined pattern is drawn on the resist film, and development is performed after the drawing, thereby forming first resist patterns 32a to 32d (see FIG. 4B).
The first resist pattern 32a covers the regions of the light shielding part 11, the light transmitting part 12, and the fifth semi-transparent part 13F of the photomask to be manufactured, and the first resist pattern 32b is the fourth semi-transparent part 13E. This is a resist pattern for forming a predetermined fine pattern in the region. The first resist pattern 32c is a resist pattern for forming a fine pattern of a semi-transparent film in the region of the second semi-transparent portion 13B, and 32d is the third and sixth semi-transparent portions 13C. , 13D, a resist pattern for forming a fine pattern of a semi-translucent film.

次に、上記第１レジストパターン３２ａ〜３２ｄをエッチングマスクとして遮光層１５ａ及び反射防止層１５ｂの積層からなる遮光膜１５をエッチングして遮光膜パターンを形成する（図４（ｃ）参照）。クロムを主成分とする遮光膜１５を用いた場合、エッチング手段としては、ドライエッチングもしくはウェットエッチングのどちらでも可能であるが、たとえば大型サイズのフォトマスク製造に好適なウェットエッチングでは、エッチング液として例えば硝酸第二セリウムアンモニウムを用いる。   Next, using the first resist patterns 32a to 32d as an etching mask, the light shielding film 15 formed by stacking the light shielding layer 15a and the antireflection layer 15b is etched to form a light shielding film pattern (see FIG. 4C). When the light shielding film 15 mainly composed of chromium is used, the etching means can be either dry etching or wet etching. For example, in wet etching suitable for manufacturing a large size photomask, Ceric ammonium nitrate is used.

残存する第１レジストパターン３２ａ〜３２ｄを除去した後（図４（ｄ）参照）、パターニングされた遮光膜１５を含む基板全面に、半透光膜１６を成膜する（図４（ｅ）参照）。
上記半透光膜１６としては、例えば前述の実施の形態と同様、金属シリサイド化合物、特にモリブデンシリサイド化合物（MoSixのほか、MoSiの窒化物、酸化物、酸化窒化物、炭化物など）が好ましく挙げられる。また、本実施の形態では、上記半透光膜１６は、遮光膜１５とのエッチング選択性はとくに要求されないため、例えば遮光膜と同様、クロム又はクロム系化合物を用いることもできる。クロム系化合物には、酸化クロム(ＣｒＯｘ)、窒化クロム(ＣｒＮｘ)、炭化クロム(ＣｒＣｘ)、酸窒化クロム(ＣｒＯｘＮ)、フッ化クロム(ＣｒＦｘ)や、これらに炭素や水素を含むものがある。上記半透光膜１６は、透明基板１４（透光部）の露光光の透過量に対し１０〜８０％程度、好ましくは２０〜７０％程度の透過量を有するものが好ましい。 After removing the remaining first resist patterns 32a to 32d (see FIG. 4D), a semi-transmissive film 16 is formed on the entire surface of the substrate including the patterned light shielding film 15 (see FIG. 4E). ).
As the semi-transparent film 16, for example, a metal silicide compound, in particular, a molybdenum silicide compound (MoSix, MoSi nitride, oxide, oxynitride, carbide, etc.) is preferably mentioned as in the above-described embodiment. . In the present embodiment, the semi-transparent film 16 is not particularly required to have etching selectivity with respect to the light shielding film 15, and therefore, for example, chromium or a chromium-based compound can be used as in the case of the light shielding film. The chromium-based compounds include chromium oxide (CrOx), chromium nitride (CrNx), chromium carbide (CrCx), chromium oxynitride (CrOxN), chromium fluoride (CrFx), and those containing carbon and hydrogen. The semi-transparent film 16 preferably has a transmission amount of about 10 to 80%, preferably about 20 to 70% with respect to the transmission amount of exposure light of the transparent substrate 14 (translucent portion).

次に、再び全面に上記と同じレジスト膜を形成し、２度目の描画を行う。すなわち、このレジスト膜に対し、所定のパターンを描画し、描画後に現像を行うことにより、第２レジストパターン３３ａ〜３３ｄを形成する（図４（ｆ）参照）。該第２レジストパターン３３ａは、製造されるフォトマスクの遮光部１１と第１半透光部１３Ａの領域を覆い、３３ｂは、第４半透光部１３Ｅの領域に形成された微細パターンのうち半透光膜１６の微細パターンを覆い、さらに第５半透光部１３Ｆの領域に所定の微細パターンを形成するためのレジストパターンを含む。また、第２レジストパターン３３ｃは、第２半透光部１３Ｂの領域に遮光膜の微細パターンを形成するためのレジストパターンを含み、また３３ｄは、第３、第６半透光部１３Ｃ，１３Ｄの領域を覆うレジストパターンである。
ここで、たとえば第４半透光部１３Ｅの領域に形成された微細パターンのうち半透光膜１６の微細パターンを覆うレジストパターン３３ｂを形成するための描画工程においては、上記１度目の描画との位置あわせが重要となる。位置ずれが発生すると、パターン加工された半透光膜１６で形成されるはずの半透光部１３Ｅに、遮光膜が残存してしまうおそれがある。なお、前述の第１の実施の形態における製造方法は、この位置あわせの課題が軽減される点で優れているといえる。 Next, the same resist film as described above is formed again on the entire surface, and a second drawing is performed. That is, a predetermined pattern is drawn on the resist film, and development is performed after the drawing, thereby forming second resist patterns 33a to 33d (see FIG. 4F). The second resist pattern 33a covers the regions of the light shielding portion 11 and the first semi-transparent portion 13A of the photomask to be manufactured, and 33b is a fine pattern formed in the region of the fourth semi-transparent portion 13E. A resist pattern for covering the fine pattern of the semi-transparent film 16 and further forming a predetermined fine pattern in the region of the fifth semi-transparent portion 13F is included. The second resist pattern 33c includes a resist pattern for forming a fine pattern of a light-shielding film in the region of the second semi-transparent portion 13B, and 33d is the third and sixth semi-transparent portions 13C and 13D. This is a resist pattern covering the region.
Here, for example, in the drawing process for forming the resist pattern 33b that covers the fine pattern of the semi-transmissive film 16 among the fine patterns formed in the region of the fourth semi-transmissive part 13E, Alignment of is important. When the positional deviation occurs, the light shielding film may remain in the semi-translucent portion 13E that should be formed by the patterned semi-transparent film 16. It can be said that the manufacturing method in the first embodiment described above is excellent in that this alignment problem is reduced.

次に、上記第２レジストパターン３３ａ〜３３ｄをマスクとして、露出した領域上の半透光膜１６とその下層の遮光膜１５を連続してエッチングする（図４（ｇ）参照）。   Next, using the second resist patterns 33a to 33d as a mask, the semi-transparent film 16 on the exposed region and the light shielding film 15 therebelow are continuously etched (see FIG. 4G).

そして、残存する第２レジストパターン３３ａ〜３３ｄを除去する。こうして、透明基板１４上に、遮光層１５ａ及び反射防止層１５ｂからなる遮光膜１５と半透光膜１６との積層によりなる遮光部１１、透明基板１４が露出する透光部１２、及び、上記半透光膜１６によりなる第１半透光部１３Ａと、上記と同じ半透光膜１６の微細パターン１７と、上記遮光部と同じ遮光膜１５と半透光膜１６の積層膜の微細パターン１８と、微細隙間（スペース部分）とからなる露光条件下における解像限界以下の線幅をもつ微細パターンによりなる第２半透光部１３Ｂと、上記遮光膜１５と半透光膜１６の積層膜の微細パターン１８と、該微細パターン１８間に形成された上記半透光膜１６の微細パターンとからなる露光条件下における解像限界以下の線幅をもつ微細パターンによりなる第３半透光部１３Ｃと、上記と同じ半透光膜１６で形成された露光条件下において解像限界以下の微細パターン１７によりなる第４半透光部１３Ｅと、上記遮光部と同じ遮光膜１５と半透光膜１６の積層膜で形成された露光条件下において解像限界以下の微細パターン１８によりなる第５半透光部１３Ｆと、上記第３半透光部１３Ｃにおける半透光膜１６で形成された微細パターンの線幅と遮光膜１５で形成された微細パターン１８の線幅が異なる幅に形成された第６半透光部１３Ｄを有するマスクパターンが形成された、露光光透過率が例えば９段階に異なる９階調のフォトマスク１０が出来上がる（図４（ｈ）参照）。   Then, the remaining second resist patterns 33a to 33d are removed. Thus, on the transparent substrate 14, the light-shielding portion 11 formed by stacking the light-shielding film 15 and the semi-transparent film 16 including the light-shielding layer 15a and the antireflection layer 15b, the light-transmitting portion 12 from which the transparent substrate 14 is exposed, and the above 13A of 1st semi-transparent parts which consist of the semi-transparent film 16, the fine pattern 17 of the same semi-transparent film 16 as the above, and the fine pattern of the laminated film of the same light-shield film 15 and the semi-transparent film 16 as the said light-shielding part 18 and a second semi-transparent portion 13B having a fine pattern having a line width less than the resolution limit under the exposure conditions including a fine gap (space portion), and the light shielding film 15 and the semi-transparent film 16 are laminated. A third semi-transparent light comprising a fine pattern having a line width less than or equal to the resolution limit under an exposure condition comprising the fine pattern 18 of the film and the fine pattern of the semi-transmissive film 16 formed between the fine patterns 18. Part 13C and the above A fourth semi-transparent portion 13E having a fine pattern 17 below the resolution limit under the exposure conditions formed by the same semi-transparent film 16, and a laminated film of the same light-shielding film 15 and the semi-transparent film 16 as the light-shielding portion The line width of the fine pattern formed by the semi-transparent film 13 in the fifth semi-transparent portion 13F and the third semi-transparent portion 13C formed by the fine pattern 18 below the resolution limit under the exposure conditions formed in FIG. The mask pattern having the sixth semi-transparent portion 13D formed with different widths of the fine pattern 18 formed of the light shielding film 15 and the light shielding film 15 is formed. The photomask 10 is completed (see FIG. 4H).

［第３の実施の形態］
次に、図５に従って本発明の第３の実施の形態を説明する。図５は第３の実施の形態に係る多階調フォトマスク１０の製造工程を工程順に示す断面図である。なお、前述の第１の実施の形態を示す図１、図２と同等の箇所には同一の符号を付している。
使用するフォトマスクブランク（図５（ａ））は、図４（ａ）と同様、ガラス基板等の透明基板１４上に、遮光層１５ａ及び反射防止層１５ｂの積層からなる遮光膜１５が形成されている。 [Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 5 is a cross-sectional view showing the manufacturing steps of the multi-tone photomask 10 according to the third embodiment in the order of steps. In addition, the same code | symbol is attached | subjected to the location equivalent to FIG. 1, FIG. 2 which shows the above-mentioned 1st Embodiment.
In the photomask blank (FIG. 5A) to be used, a light shielding film 15 made of a laminate of a light shielding layer 15a and an antireflection layer 15b is formed on a transparent substrate 14 such as a glass substrate, as in FIG. 4A. ing.

まず、上記フォトマスクブランク上にレジストを塗布してレジスト膜を形成し、１度目の描画を行う。上記レジストとしてはポジ型フォトレジストを使用する。そして、レジスト膜に対し、所定のパターンを描画し、描画後に現像を行うことにより、第１レジストパターン３４を形成する（図５（ｂ）参照）。
該第１レジストパターン３４は、製造されるフォトマスクの遮光部１１の領域を覆うとともに、半透光部１３Ｂ〜１３Ｄ、１３Ｆの領域にそれぞれ所定の微細パターンを形成するためのレジストパターンを含む。 First, a resist is applied on the photomask blank to form a resist film, and a first drawing is performed. A positive photoresist is used as the resist. Then, a predetermined pattern is drawn on the resist film, and development is performed after the drawing, thereby forming the first resist pattern 34 (see FIG. 5B).
The first resist pattern 34 includes a resist pattern for covering a region of the light shielding part 11 of the photomask to be manufactured and forming a predetermined fine pattern in each of the semi-transparent parts 13B to 13D and 13F.

次に、上記第１レジストパターン３４をエッチングマスクとして遮光層１５ａ及び反射防止層１５ｂの積層からなる遮光膜１５をエッチングして遮光膜パターンを形成する（図５（ｃ）参照）。クロムを主成分とする遮光膜１５を用いた場合、エッチング手段としては、ドライエッチングもしくはウェットエッチングのどちらでも可能であるが、たとえば大型サイズのフォトマスク製造に好適なウェットエッチングでは、エッチング液として例えば硝酸第二セリウムアンモニウムを用いる。   Next, by using the first resist pattern 34 as an etching mask, the light shielding film 15 formed by stacking the light shielding layer 15a and the antireflection layer 15b is etched to form a light shielding film pattern (see FIG. 5C). When the light shielding film 15 mainly composed of chromium is used, the etching means can be either dry etching or wet etching. For example, in wet etching suitable for manufacturing a large size photomask, Ceric ammonium nitrate is used.

残存する第１レジストパターン３４を除去した後（図５（ｄ）参照）、パターニングされた遮光膜１５を含む基板全面に、半透光膜１６を成膜する（図５（ｅ）参照）。
上記半透光膜１６としては、例えば前述の第２の実施の態様と同様のものが用いられる。上記半透光膜１６は、透明基板１４（透光部）の露光光の透過量に対し１０〜８０％程度、好ましくは２０〜７０％程度の透過量を有するものが好ましい。 After removing the remaining first resist pattern 34 (see FIG. 5D), a semi-transparent film 16 is formed on the entire surface of the substrate including the patterned light shielding film 15 (see FIG. 5E).
As the semi-transparent film 16, for example, the same film as in the second embodiment described above is used. The semi-transparent film 16 preferably has a transmission amount of about 10 to 80%, preferably about 20 to 70% with respect to the transmission amount of exposure light of the transparent substrate 14 (translucent portion).

次に、再び全面に上記と同じレジスト膜を形成し、２度目の描画を行う。すなわち、このレジスト膜に対し、所定のパターンを描画し、描画後に現像を行うことにより、第２レジストパターン３５を形成する（図５（ｆ）参照）。該第２レジストパターン３５は、製造されるフォトマスクの遮光部１１及び半透光部１３Ａの領域を覆うとともに、半透光部１３Ｃ，１３Ｄの領域に形成された微細パターンを覆うレジストパターンと、半透光部１３Ｂの領域に形成された遮光膜の微細パターンを覆うと同時にかかる遮光膜の微細パターン間に半透光膜の微細パターンを形成するためのレジストパターンと、半透光部１３Ｅの領域に半透光膜の微細パターンを形成するためのレジストパターンと、半透光部１３Ｆの領域に形成された遮光膜の微細パターンを覆うレジストパターンを含む。
次に、上記第２レジストパターン３５をマスクとして、露出した領域上の半透光膜１６をエッチングする（図５（ｇ）参照）。 Next, the same resist film as described above is formed again on the entire surface, and a second drawing is performed. That is, a second resist pattern 35 is formed by drawing a predetermined pattern on the resist film and performing development after the drawing (see FIG. 5F). The second resist pattern 35 covers a region of the light-shielding part 11 and the semi-transparent part 13A of the photomask to be manufactured, and also covers a fine pattern formed in the areas of the semi-transparent parts 13C and 13D, A resist pattern for covering the fine pattern of the light-shielding film formed in the region of the semi-light-transmissive portion 13B and at the same time forming a fine pattern of the semi-light-transmissive film between the fine patterns of the light-shielding film, and the semi-light-transmissive portion 13E A resist pattern for forming a fine pattern of the semi-transparent film in the region and a resist pattern covering the fine pattern of the light shielding film formed in the region of the semi-transparent portion 13F are included.
Next, the semi-transparent film 16 on the exposed region is etched using the second resist pattern 35 as a mask (see FIG. 5G).

そして、残存する第２レジストパターン３５を除去する。こうして、透明基板１４上に、遮光層１５ａ及び反射防止層１５ｂからなる遮光膜１５と半透光膜１６との積層によりなる遮光部１１、透明基板１４が露出する透光部１２、及び、上記半透光膜１６によりなる第１半透光部１３Ａと、上記と同じ半透光膜１６の微細パターン１７と、上記遮光部と同じ遮光膜１５と半透光膜１６の積層膜の微細パターン１８と、隙間部分（スペース部分）とからなる露光条件下における解像限界以下の線幅をもつ微細パターンによりなる第２半透光部１３Ｂと、上記遮光膜１５と半透光膜１６の積層膜の微細パターン１８と、該微細パターン１８間に形成された上記半透光膜１６の微細パターンとからなる露光条件下における解像限界以下の線幅をもつ微細パターンによりなる第３半透光部１３Ｃと、上記と同じ半透光膜１６で形成された露光条件下において解像限界以下の微細パターン１７によりなる第４半透光部１３Ｅと、上記遮光部と同じ遮光膜１５と半透光膜１６の積層膜で形成された露光条件下において解像限界以下の微細パターン１８によりなる第５半透光部１３Ｆと、上記第３半透光部１３Ｃにおける半透光膜１６で形成された微細パターンの線幅と遮光膜１５で形成された微細パターン１８の線幅が異なる幅に形成された第６半透光部１３Ｄを有するマスクパターンが形成された、露光光透過率が例えば９段階に異なる９階調のフォトマスク１０が出来上がる（図５（ｈ）参照）。   Then, the remaining second resist pattern 35 is removed. Thus, on the transparent substrate 14, the light-shielding portion 11 formed by stacking the light-shielding film 15 and the semi-transparent film 16 including the light-shielding layer 15a and the antireflection layer 15b, the light-transmitting portion 12 from which the transparent substrate 14 is exposed, and the above 13A of 1st semi-transparent parts which consist of the semi-transparent film 16, the fine pattern 17 of the same semi-transparent film 16 as the above, and the fine pattern of the laminated film of the same light-shield film 15 and the semi-transparent film 16 as the said light-shielding part 18 and a second semi-transparent portion 13B having a fine pattern having a line width less than the resolution limit under the exposure condition including a gap portion (space portion), and the light shielding film 15 and the semi-transparent film 16 are laminated. A third semi-transparent light comprising a fine pattern having a line width less than or equal to the resolution limit under an exposure condition comprising the fine pattern 18 of the film and the fine pattern of the semi-transmissive film 16 formed between the fine patterns 18. Part 13C and the above A fourth semi-transparent portion 13E having a fine pattern 17 below the resolution limit under the exposure conditions formed by the same semi-transparent film 16, and a laminated film of the same light-shielding film 15 and the semi-transparent film 16 as the light-shielding portion The line width of the fine pattern formed by the semi-transparent film 13 in the fifth semi-transparent portion 13F and the third semi-transparent portion 13C formed by the fine pattern 18 below the resolution limit under the exposure conditions formed in FIG. The mask pattern having the sixth semi-transparent portion 13D formed with different widths of the fine pattern 18 formed of the light shielding film 15 and the light shielding film 15 is formed. The photomask 10 is completed (see FIG. 5H).

以上のように本実施の形態による多階調フォトマスクの製造方法においても、遮光膜と半透光膜との組み合わせを用い、フォトリソグラフィ法によって、半透光膜によりなる半透光部と、半透光膜の微細パターン及び遮光膜の微細パターンによりそれぞれなる半透光部を一緒に精度良く形成することができ、上記多階調フォトマスクを効率的で、かつ欠陥発生の確率の低い簡便な工程によって製造することができる。   As described above, also in the manufacturing method of the multi-tone photomask according to the present embodiment, by using a combination of a light-shielding film and a semi-transparent film, by a photolithography method, a semi-transparent portion made of a semi-transparent film, The semi-transparent part formed by the micro-pattern of the semi-transparent film and the micro-pattern of the light-shielding film can be formed together with high accuracy, and the multi-tone photomask is efficient and simple with a low probability of occurrence of defects. It can be manufactured by a simple process.

なお、上記実施の形態のうちいずれを用いて、本発明のフォトマスクを作製してもよい。なおこれらを比較すると、第２、第３の実施形態においては、２度目の描画の際に、半透光膜上のレジストに微細パターンを描画することとなるが、この半透光膜は、製品に応じた様々の透過率の半透光膜である。従って、個々に、半透光膜の膜質、膜厚が異なり、このため反射光の強度も異なるところ、微細パターンの描画に際しては、線幅、すなわち露光光量の制御が極めて精緻に行われる必要がある。一方、第１の実施形態においては、微細パターン形成のための描画は、遮光膜（含反射防止膜）上で行われるので、一定の描画条件で所定線幅を実現できる。従って、より安定した透過率の多階調フォトマスクが生産しやすい利点がある。
また、第３の実施形態（図５）によれば、遮光膜と半透光膜による微細パターンからなる半透光部において、一回目の描画によって、微細パターンを含む半透光部の膜パターンの線幅が画定し、かつ、透過率が製品によって異なる半透光膜上への描画が必要ないため、微細パターンが精度よく形成でき、透過率の制御がしやすい利点がある。
また、上記第１の実施形態で用いた、モリブデンシリサイド系の半透光膜は、２０〜７０％の透過率を得るための膜厚が薄く（１０〜２００Å程度）、サイドエッチングによるＣＤ劣化の懸念が非常に小さいため、本発明の効果が特に顕著である。
なお、本発明の多階調フォトマスクの製造方法は、上記に例示したものに限定されない。 Note that the photomask of the present invention may be manufactured using any of the above embodiments. When comparing these, in the second and third embodiments, a fine pattern is drawn on the resist on the semi-transparent film at the time of the second drawing. It is a semi-transparent film with various transmittances according to the product. Therefore, the film quality and film thickness of the semi-transparent film are different from each other, and therefore the intensity of reflected light is also different. Therefore, when drawing a fine pattern, it is necessary to control the line width, that is, the amount of exposure light very precisely. is there. On the other hand, in the first embodiment, drawing for forming a fine pattern is performed on a light-shielding film (an antireflection film), so that a predetermined line width can be realized under certain drawing conditions. Therefore, there is an advantage that it is easy to produce a multi-tone photomask with more stable transmittance.
Further, according to the third embodiment (FIG. 5), the film pattern of the semi-transparent part including the fine pattern is drawn by the first drawing in the semi-transparent part composed of the fine pattern of the light shielding film and the semi-transparent film. Therefore, there is an advantage that a fine pattern can be formed with high accuracy and the transmittance can be easily controlled.
Further, the molybdenum silicide semi-transparent film used in the first embodiment has a thin film thickness (about 10 to 200 mm) for obtaining a transmittance of 20 to 70%, and CD deterioration due to side etching is reduced. Since the concern is very small, the effect of the present invention is particularly remarkable.
In addition, the manufacturing method of the multi-tone photomask of this invention is not limited to what was illustrated above.

本発明に係る多階調フォトマスクの第１の実施の形態と、当該多階調フォトマスクを用いたパターン転写方法を説明するための断面図である。It is sectional drawing for demonstrating 1st Embodiment of the multi-tone photomask which concerns on this invention, and the pattern transfer method using the said multi-tone photomask. 上記第１の実施の形態に係る多階調フォトマスクの製造工程を工程順に示す断面図である。It is sectional drawing which shows the manufacturing process of the multi-tone photomask which concerns on the said 1st Embodiment in process order. 第１の実施の形態に係る多階調フォトマスクの他の製造工程を工程順に示す断面図である。It is sectional drawing which shows the other manufacturing process of the multi-tone photomask which concerns on 1st Embodiment in order of a process. 第２の実施の形態にかかる多階調フォトマスクの製造工程を工程順に示す断面図である。It is sectional drawing which shows the manufacturing process of the multi-tone photomask concerning 2nd Embodiment in order of a process. 第３の実施の形態に係る多階調フォトマスクの製造工程を工程順に示す断面図である。It is sectional drawing which shows the manufacturing process of the multi-tone photomask which concerns on 3rd Embodiment in process order. 遮光部Ａに挟まれた半透光部Ｂのパターン（同図（１））と、該半透光部Ｂの透過光の光強度分布（同図（２））を示し、同図（ａ）は半透光領域の幅が４μｍ、同図（ｂ）は２μｍの場合を示す。The pattern of the semi-translucent part B sandwiched between the light-shielding parts A (FIG. 1A) and the light intensity distribution of the transmitted light of the semi-transparent part B (FIG. 2B) are shown. ) Shows a case where the width of the semi-translucent region is 4 μm, and FIG. チャネル幅と該チャネル幅に対応した幅の半透光部における露光光の透過率との関係を示す図である。It is a figure which shows the relationship between the transmittance | permeability of exposure light in the semi-transmission part of the width | variety corresponding to the channel width and this channel width.

符号の説明Explanation of symbols

１０ 多階調フォトマスク
１１ 遮光部
１２ 透光部
１３Ａ 第１半透光部
１３Ｂ 第２半透光部
１３Ｃ 第３半透光部
１４ 透明基板
１５ 遮光膜
１６ 半透光膜
１７ 半透光膜の微細パターン
１８ 遮光膜の微細パターン
２０ 被転写体
２３ レジストパターン
DESCRIPTION OF SYMBOLS 10 Multi-gradation photomask 11 Light-shielding part 12 Light-transmitting part 13A 1st semi-light-transmitting part 13B 2nd semi-light-transmitting part 13C 3rd semi-light-transmitting part 14 Transparent substrate 15 Light-shielding film 16 Semi-light-transmitting film 17 Semi-light-transmitting film Fine pattern 18 Light-shielding film fine pattern 20 Transfer object 23 Resist pattern

Claims (5)

透明基板上に、遮光部、透光部、及び露光光透過率を所定量低減させる、パターン幅５μｍ以下の部分を有する半透光部をもつマスクパターンを有する多階調フォトマスクであって、
前記遮光部は、少なくとも前記透明基板上に形成された遮光膜により形成され、
前記透光部は、露出した前記透明基板により形成され、かつ、
前記多階調フォトマスクは、２乃至７種類の異なる種類の半透光部を有し、該２乃至７種類の半透光部は、パターンの寸法が異なるとともに被転写体上に同一のレジスト残膜値を有するレジストパターンを形成することができる、異なる種類の半透光部を含み、
前記２乃至７種類の半透光部は、半透光膜により形成された部分、半透光膜の微細パターンと遮光膜の微細パターンの組合せにより形成された部分、半透光膜の微細パターンにより形成された部分、及び遮光膜の微細パターンにより形成された部分、のいずれかの種類から構成されることを特徴とする多階調フォトマスク。 On a transparent substrate, the light shielding portion, the translucent portion, and reducing a predetermined amount of exposure light transmittance, a multi-tone photomask have a mask pattern having a semi-light-transmitting portion having the following partial pattern width 5μm ,
The light shielding part is formed by at least a light shielding film formed on the transparent substrate,
The translucent part is formed by the exposed transparent substrate, and
The multi-tone photomask has two to seven different types of semi-transparent portions, and the two to seven types of semi-transparent portions have different pattern dimensions and the same resist on the transfer target. Including different types of semi-transparent portions capable of forming a resist pattern having a residual film value;
The two to seven kinds of semi-transparent portions are a part formed by a semi-transparent film, a part formed by a combination of a micro-pattern of the semi-transparent film and a micro-pattern of the light shielding film, and a micro pattern of the semi-transparent film. A multi-tone photomask comprising any one of a part formed by the above and a part formed by a fine pattern of a light shielding film . 前記遮光膜はクロムを主成分とした材料からなり、前記半透光膜は金属シリサイドを主成分とした材料からなることを特徴とする請求項１に記載の多階調フォトマスク。 2. The multi-tone photomask according to claim 1, wherein the light shielding film is made of a material containing chromium as a main component, and the semi-transparent film is made of a material containing metal silicide as a main component. 前記遮光部は、少なくとも前記半透光膜と前記遮光膜が積層されてなり、前記半透光膜と前記遮光膜の間に、エッチングストッパ膜を有することを特徴とする請求項１に記載の多階調フォトマスク。 The light shielding portion is constituted by laminating at least the semi-transparent film and the light-shielding film, between the semi-transparent film and the light-shielding film, according to claim 1, characterized in that it comprises an etching stopper film Multi-tone photomask. 透明基板上に、遮光部、透光部、及び露光光透過率を所定量低減させる、パターン幅５μｍ以下の部分を有する半透光部をもつマスクパターンを有する多階調フォトマスクであって、
前記遮光部は、少なくとも前記透明基板上に形成された遮光膜により形成され、
前記透光部は、露出した前記透明基板により形成され、かつ、
前記多階調フォトマスクは、前記透明基板上に形成された半透光膜によりなる第１半透光部と、前記透明基板上に形成された、前記半透光膜の微細パターン、前記遮光膜の微細パターン、及び前記半透光膜及び前記遮光膜が形成されていない微細隙間を含み、露光条件下における解像限界以下の線幅をもつ微細パターンが形成されてなる第２半透光部、又は、前記半透光膜の微細パターンと前記遮光膜の微細パターンとからなる露光条件下における解像限界以下の線幅をもつ微細パターンが形成されてなる第３半透光部とを有し、
前記第１乃至第３半透光部は、パターンの寸法が異なるとともに被転写体上に同一のレジスト残膜値を有するレジストパターンを形成することができる、異なる種類の半透光部を含むことを特徴とする多階調フォトマスク。 On a transparent substrate, the light shielding portion, the translucent portion, and reducing a predetermined amount of exposure light transmittance, a multi-tone photomask have a mask pattern having a semi-light-transmitting portion having the following partial pattern width 5μm ,
The light shielding part is formed by at least a light shielding film formed on the transparent substrate,
The translucent part is formed by the exposed transparent substrate, and
The multi-tone photomask includes a first semi-transparent portion made of a semi-transparent film formed on the transparent substrate, a fine pattern of the semi-transparent film formed on the transparent substrate, and the light shielding. A second semi-transparent light formed by forming a fine pattern of the film, and a fine pattern having a line width less than a resolution limit under exposure conditions, including a fine gap in which the semi-transparent film and the light-shielding film are not formed. Or a third semi-transparent part formed with a fine pattern having a line width less than the resolution limit under exposure conditions comprising the fine pattern of the semi-transparent film and the fine pattern of the light-shielding film. has,
The first to third semi-transparent portions include different types of semi-transparent portions that have different pattern dimensions and can form resist patterns having the same resist residual film value on the transfer target. Multi-tone photomask characterized by 請求項１乃至４のいずれかに記載の多階調フォトマスクを用いて、被転写体に露光光を照射する露光工程を有し、被転写体上に多階調の転写パターンを形成することを特徴とするパターン転写方法。 Using a multi-tone photomasks any crab of claims 1 to 4, comprising an exposure step of irradiating the exposure light transfer object, to form a multi-gradation of the transfer pattern onto the transfer member A pattern transfer method.
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