Method for manufacturing a photomask and a photomask

Abstract

To provide a method of producing a photomask capable of forming a fine pattern exceeding drawing performance of a drawing apparatus, and a photomask.SOLUTION: The first invention is a method of producing a photomask having a line and space pattern including: i) dividing the line and space pattern into a plurality of groups line by line so that lines abutting each other are not included in the same group; and ii) patterning a respective plural kinds of films 3A, 3B respectively formed in correspondence with the respective groups and having different etching characteristics from each other so as to form lines pertaining to corresponding groups.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a photomask and a photomask.

Background Art

[0002] A photomask is manufactured through the steps of: i) preparing a photomask blank in which a light-shielding film is formed on the surface of a transparent substrate; ii) forming a resist film on the surface of the photomask blank; iii) drawing a predetermined resist pattern on the resist film, removing the unnecessary resist film by development, and forming a predetermined resist pattern; iv) using the resist pattern as a mask and removing the exposed portion of the light-shielding film by etching; and v) removing the remaining resist film. As a result, the photomask includes a light-shielding portion of a predetermined pattern where the light-shielding film remains and a transmissive portion where the transparent substrate is exposed.

[0003] As a typical pattern, there is a line and space pattern. The line and space pattern is a pattern in which lines (light-shielding portions) with a width in μm units and spaces (gaps) (transmissive portions) with a width in μm units are alternately repeated (see Patent Document 1). Also, a hole pattern is a pattern often used. The hole pattern is a pattern in which holes are two-dimensionally arranged (see Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in recent years, with the improvement of the image quality of flat panel displays such as liquid crystal displays and organic EL displays, pattern miniaturization has progressed in large-sized photomasks used in the production of these displays.

[0006] However, the pattern depends on the drawing performance of the drawing apparatus in the above step iii), that is, the resolution of the drawing apparatus. It is not possible to miniaturize the pattern beyond the resolution limit of the drawing apparatus.

[0007] Therefore, the present invention has been made in view of such circumstances, and an object thereof is to provide a method for manufacturing a photomask and a photomask capable of forming a fine pattern exceeding the drawing performance of a drawing apparatus.

Means for Solving the Problems

[0009] The method for manufacturing a photomask according to the first invention No. 1 is a method for manufacturing a photomask having a line-and-space pattern composed of at least one type of film selected from a light-shielding film, a semi-transmissive film, and a phase-shifting film, wherein the line-and-space pattern is divided into a plurality of groups in units of lines so that adjacent lines are not included in the same group, and each of a plurality of types of films formed corresponding to each group and having different etching characteristics from each other is patterned so as to form the lines corresponding to the corresponding group. In the method for manufacturing a photomask, A photomask blank preparation step of preparing a photomask blank in which a film corresponding to one group is formed on the surface of a transparent substrate, A patterning step of patterning the film corresponding to one group so as to form a line related to the group, A film formation step of forming a film corresponding to another group, And a patterning step of patterning the film corresponding to another group so as to form a line related to the group in this order are provided it is a method for manufacturing a photomask.

[0010] The method for manufacturing a photomask according to the second invention No. 1 is a method for manufacturing a photomask having a line-and-space pattern composed of at least one type of film selected from a light-shielding film, a semi-transmissive film, and a phase-shifting film, and each line being either only a light-shielding portion, only a semi-transmissive portion, or only a phase-shifting portion, wherein the line-and-space pattern is divided into a plurality of groups in units of lines so that adjacent lines are not included in the same group, and each of a plurality of types of films formed corresponding to each group and having different etching characteristics from each other is patterned so as to form the lines corresponding to the corresponding group. In the method for manufacturing a photomask, A photomask blank preparation step of preparing a photomask blank in which films corresponding to each group are laminated and formed on the surface of a transparent substrate, A patterning step of patterning the film corresponding to one group so as to form a line related to the group, And a patterning step of patterning the film corresponding to another group so as to form a line related to the group it is a method for manufacturing a photomask.

[0011] A method for manufacturing a photomask according to a second invention is Composed of at least one type of film selected from a light-shielding film, a semi-transmissive film, and a phase-shifting film A method for manufacturing a photomask having a polygonal hole pattern, The hole pattern is divided into a plurality of groups in units of sides so that adjacent sides are not included in the same group, Each of a plurality of types of films that are respectively formed corresponding to each group and have different etching characteristics from each other is patterned so as to form a side related to the corresponding group It is a method for manufacturing a photomask.

[0012] Here, as one aspect of the method for manufacturing a photomask according to the second invention, A photomask blank preparation step of preparing a photomask blank in which a film corresponding to one group is formed on the surface of a transparent substrate, A patterning step of patterning the film corresponding to one group so as to form a side related to the group, A film forming step of forming a film corresponding to another group, And a patterning step of patterning the film corresponding to another group so as to form a side related to the group A configuration as described above can be adopted.

[0013] Further, as another aspect of the method for manufacturing a photomask according to the second invention, A photomask blank preparation step of preparing a photomask blank in which films corresponding to each group are laminated and formed on the surface of a transparent substrate, A patterning step of patterning a film corresponding to one group so as to form a side related to the group, and a patterning step of patterning a film corresponding to another group so as to form a side related to the group. The configuration as described above can be adopted.

[0014] Also, in these cases, a direction changing step of changing the direction of the photomask blanks is further provided so that each side is formed along the scanning direction of drawing in each patterning step. The configuration as described above can be adopted.

[0015] The photomask according to the first invention has a line and space pattern formed using at least one type of film selected from a light-shielding film, a semi-transmissive film, and a phase shift film. and each line is either only a light-shielding portion, only a semi-transmissive portion, or only a phase-shifting portion The photomask is such that each line is formed of a film having etching characteristics different from those of an adjacent line. The photomask is as described above. Here, as one aspect of the photomask according to the first invention, having a line-and-space pattern with a pitch smaller than the limit of the drawing performance of the drawing apparatus used in the patterning process a configuration as such can be adopted. Also, as one aspect of the photomask according to the first invention, having a line-and-space pattern with a pitch of 0.8 μm or less a configuration as such can be adopted.

[0016] The photomask according to the second invention Composed of at least one type of film selected from a light-shielding film, a semi-transmissive film, and a phase-shifting film is a photomask having a polygonal hole pattern, wherein each side is formed by an edge of a film having etching characteristics different from those of an adjacent side. The photomask is as described above.

Advantages of the Invention

[0017] According to the present invention, by utilizing the fact that the etching characteristics of each film are different, a fine pattern exceeding the drawing performance of a drawing apparatus can be formed.

Brief Description of the Drawings

[0018]

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MODE FOR CARRYING OUT THE INVENTION

[0019] <Embodiment 1> Hereinafter, Embodiment 1 of the present invention will be described with reference to FIGS. 1 to 4. First, the configuration of the photomask 1 will be described.

[0020] As shown in FIG. 1, the photomask 1 is a photomask having a line and space pattern (hereinafter referred to as an "L / S pattern") in which lines (light-shielding portions) having a width in μm units and spaces (transmission portions) having a width in μm units are alternately repeated. The L / S pattern is an equally spaced L / S pattern in which the line and the space have the same width.

[0021] In the photomask 1, a light-shielding film 3 is laminated on the surface of a transparent substrate 2, and the portion where the light-shielding film 3 is laminated becomes a light-shielding portion. On the other hand, the portion where the transparent substrate 2 not laminated with the light-shielding film 3 is exposed becomes a transmissive portion.

[0022] The transparent substrate 2 is a substrate such as synthetic quartz glass. The transparent substrate 2 has a transmittance of 95% or more with respect to the representative wavelength (for example, i-line, h-line, or g-line) included in the exposure light used in the exposure process using the photomask 1. Note that the exposure light may be, for example, i-line, h-line, or g-line, or may be mixed light including at least two of these lights. However, the exposure light is not limited to these.

[0023] The light-shielding film 3 has a transmittance of 1% or less with respect to the representative wavelength included in the exposure light. Alternatively, even if the transmittance of the light-shielding film 3 is higher than 1%, it is sufficient that the laminated transmittance in the light-shielding portion is 1% or less. Alternatively, it is sufficient that the optical density (OD value) in the light-shielding portion satisfies 2.7 or more. The light-shielding film 3 is formed on the surface of the transparent substrate 2 by a sputtering method, an evaporation method, or the like.

[0024] The light-shielding film 3 includes a first light-shielding film 3A and a second light-shielding film 3B. The L / S pattern is an L / S pattern in which the lines formed by the first light-shielding film 3A and the lines formed by the second light-shielding film 3B are alternately repeated with a space therebetween.

[0025] One of the first light-shielding film 3A or the second light-shielding film 3B uses a Cr-based material among known materials such as Cr or Cr-based compounds, Ni or Ni-based compounds, Ti or Ti-based compounds, Si-based compounds, and metal silicide compounds. The other of the first light-shielding film 3A or the second light-shielding film 3B uses a non-Cr-based material. Thus, since the first light-shielding film 3A and the second light-shielding film 3B have different materials, their etching characteristics are different from each other. That is, the first light-shielding film 3A has an etching selectivity with respect to the second light-shielding film 3B, and the second light-shielding film 3B has an etching selectivity with respect to the first light-shielding film 3A.

[0026] Next, a method for manufacturing the photomask 1 will be described.

[0027] The manufacturing method of the photomask 1 includes: i) a photomask blank preparation step (step 1), ii) a resist film formation step (step 2), iii) a drawing step (step 3), iv) a development step (step 4), v) a light-shielding film etching step (step 5), vi) a resist film removal step (step 6), vii) a light-shielding film formation step (step 7), viii) a resist film formation step (step 8), ix) a drawing step (step 9), x) a development step (step 10), xi) a light-shielding film etching step (step 11), and xii) a resist film removal step (step 12). The steps from the resist film formation step (step 2) to the resist film removal step (step 6) and the steps from the resist film formation step (step 8) to the resist film removal step (step 12) are each referred to as a patterning step.

[0028] In the photomask blank preparation step (step 1), as shown in Fig. 2(a), a photomask blank having a first light-shielding film 3A formed on the surface of a transparent substrate 2 is prepared. The first light-shielding film 3A is formed by a sputtering method, an evaporation method, or the like.

[0029] In the first resist film formation step (step 2), as shown in Fig. 2(b), a resist is uniformly applied to the surface of the photomask blank to form a resist film 4. The resist is applied by a coating method or a spray method.

[0030] In the first drawing step (step 3), as shown in Fig. 2(c), the resist film 4 is irradiated with exposure light using an electron beam or a laser of a drawing apparatus to draw a predetermined resist pattern. The resist pattern includes an L / S pattern. Alternatively, the resist pattern is an L / S pattern. In this example, the resist pattern includes an uneven pitch L / S pattern with a ratio a:b = 1:3 between the width a of the irradiated portion (if it is a positive resist, the non-irradiated portion) and the width b of the non-irradiated portion (if it is a positive resist, the irradiated portion). Note that b = 3 is the value when the width of the line (= a) + 2 × the width of the space, and the width of the line = the width of the space.

[0031] In the first development process (Process 4), as shown in FIG. 2(d), the unnecessary resist film 4 (portion 4a) is removed by development, and a resist pattern is formed. The development is performed by immersing in a developer. Note that the drawing process (Process 3) and the development process (Process 4) together are referred to as a resist pattern formation process.

[0032] In the first light-shielding film etching process (Process 5), as shown in FIG. 3(a), using the resist pattern as a mask for etching, the exposed portion of the first light-shielding film 3A is removed by etching. The etching may be either dry etching or wet etching, but for a large-sized photomask, wet etching is preferred. An etchant, such as an etching solution or an etching gas, is used. In any case, an etchant having etching selectivity with respect to the first light-shielding film 3A is used.

[0033] In the first resist film removal process (Process 6), as shown in FIG. 3(b), the resist film 4 is removed. The removal of the resist film 4 is performed by ashing or by immersing in a resist stripper.

[0034] In the light-shielding film formation process (Process 7), as shown in FIG. 3(c), the second light-shielding film 3B is formed over the entire surface of the transparent substrate 2 and the first light-shielding film 3A. The second light-shielding film 3B is formed by a sputtering method, an evaporation method, or the like. The film thickness of the second light-shielding film 3B is the same as that of the first light-shielding film 3A. Alternatively, the film thickness of the second light-shielding film 3B may be larger or smaller than that of the first light-shielding film 3A.

[0035] In the second resist film formation process (Process 8), similar to the first resist film formation process (Process 2), as shown in FIG. 3(d), a resist is applied onto the surface of the photomask blanks, and a resist film 4 is formed. The resist is applied by a coating method or a spray method.

[0036] In the second drawing process (Process 9), as shown in Fig. 4(a), similar to the first drawing process (Process 3), the resist film 4 is irradiated with exposure light using an electron beam or a laser of a drawing apparatus, and a predetermined resist pattern is drawn. The drawing apparatus is the same apparatus as the one used in the first drawing process (Process 3). The resist pattern includes an L / S pattern. Alternatively, the resist pattern is an L / S pattern. In this example, the resist pattern is an unequal pitch L / S pattern with a ratio a:b = 1:3 of the width a of the irradiated portion (if it is a positive resist instead of a negative resist, the non-irradiated portion) to the width b of the non-irradiated portion (if it is a positive resist, the irradiated portion), and the irradiated portion is located at the center in the width direction between adjacent lines formed by the first light-shielding film 3A and the line formed by the first light-shielding film 3A is located at the center in the width direction of the non-irradiated portion.

[0037] In the second developing process (Process 10), similar to the first developing process (Process 4), as shown in Fig. 4(b), the unnecessary resist film 4 (portion 4a) is removed by development, and a resist pattern is formed. The development is performed by immersing in a developer. Note that the drawing process (Process 9) and the developing process (Process 10) together are referred to as a resist pattern forming process.

[0038] In the second light-shielding film etching process (Process 11), as shown in Fig. 4(c), using the resist pattern as a mask for etching treatment, the exposed portion of the second light-shielding film 3B is removed by etching. The etching may be either dry etching or wet etching, but for a large-sized photomask, wet etching is preferable. An etchant such as an etching solution or an etching gas is used. Whichever etchant is used, an etchant having etching selectivity with respect to the second light-shielding film 3B (an etchant that does not etch the first light-shielding film 3A) is used, so that only the second light-shielding film 3B is selectively etched.

[0039] In the second resist film removal step (step 12), as in the first resist film removal step (step 6), the resist film 4 is removed as shown in FIG. 4(d). The removal of the resist film 4 is performed by an ashing method or by immersion in a resist stripper.

[0040] Through the above steps 1 to 12, the photomask 1 is completed.

[0041] Thus, the method for manufacturing the photomask 1 according to the present embodiment divides the L / S pattern into two groups in line units so that adjacent lines are not included in the same group, and patterns each of two light-shielding films 3A and 3B formed corresponding to each group and having different etching characteristics so as to form the lines corresponding to the corresponding group.

[0042] Further, on this premise, the method for manufacturing the photomask 1 according to the present embodiment includes: i) a photomask blank preparation step of preparing a photomask blank in which a light-shielding film 3A corresponding to one group is formed on the surface of a transparent substrate 2; ii) a patterning step of patterning the light-shielding film 3A corresponding to one group so as to form the lines corresponding to the group; iii) a light-shielding film forming step of forming a light-shielding film 3B corresponding to another group; and iv) a patterning step of patterning the light-shielding film 3B corresponding to another group so as to form the lines corresponding to the group.

[0043] According to the method for manufacturing the photomask 1 according to the present embodiment, two types of light-shielding films 3A and 3B having different etching characteristics are used, and an L / S pattern is formed by double patterning. Therefore, for example, even in a drawing apparatus in which an equally spaced L / S pattern with a line width of 0.7 μm and a pitch of 1.4 μm is the limit of drawing performance, by patterning each of the light-shielding films 3A and 3B with an L / S pattern having a line width:space width = a:b = 1:3 = 0.4 μm:1.2 μm, a fine equally spaced L / S pattern with a line width of 0.4 μm and a pitch of 0.8 μm can be formed.

[0044] Incidentally, considering the effect of pattern miniaturization, the most desirable is an equal pitch L / S pattern where the line and space have the same width, such as in this example. However, even if the lines have the same width and the spaces have the same width, but the line and space do not have the same width, an unequal pitch L / S pattern can still achieve pattern miniaturization. For example, by patterning each light-shielding film 3A, 3B with an L / S pattern where the line width:space width = 0.3 μm:1.3 μm, a fine unequal pitch L / S pattern with a line width of 0.3 μm and a pitch of 0.8 μm can be formed. Note that even for an unequal pitch L / S pattern, the ability to achieve pattern miniaturization is the same in the following embodiments.

[0045] Also, the line width:space width = 1:3 = 0.4 μm:1.2 μm is the specifications for achieving extremely high-level pattern miniaturization. Needless to say, even with looser specifications than this, it is possible to miniaturize the pattern beyond the drawing performance of the drawing apparatus. Note that this is the same in the following embodiments.

[0046] <Embodiment 2> Hereinafter, Embodiment 2 of the present invention will be described with reference to FIGS. 5 to 8. In the following, the differences from Embodiment 1 will be described, and the same points will be omitted assuming the description for Embodiment 1 is the same.

[0047] As shown in FIG. 5, the photomask 1 is a photomask having an L / S pattern in which the lines formed by the first light-shielding film 3A and the lines formed by the laminated film of the first light-shielding film 3A and the second light-shielding film 3B are alternately repeated with a space in between. The L / S pattern is an equal pitch L / S pattern where the line and space have the same width.

[0048] As shown in FIGS. 6 to 8, the method for manufacturing the photomask 1 includes: i) a photomask blank preparation step (step 1), ii) a resist film formation step (step 2), iii) a drawing step (step 3), iv) a development step (step 4), v) a light-shielding film etching step (step 5), vi) a resist film removal step (step 6), vii) a resist film formation step (step 7), viii) a drawing step (step 8), ix) a development step (step 9), x) a light-shielding film etching step (step 10), and xi) a resist film removal step (step 11). The steps from the resist film formation step (step 2) to the resist film removal step (step 6) and the steps from the resist film formation step (step 7) to the resist film removal step (step 11) are each referred to as a patterning step.

[0049] In the photomask blank preparation step (step 1), as shown in FIG. 6(a), a first light-shielding film 3A is formed on the surface of the transparent substrate 2, and a second light-shielding film 3B is formed on the surface of the first light-shielding film 3A. Thus, a photomask blank in which the first light-shielding film 3A and the second light-shielding film 3B are laminated and formed on the surface of the transparent substrate 2 is prepared.

[0050] In the first drawing step (step 3), as shown in FIG. 6(c), the resist film 4 is irradiated with exposure light using an electron beam or a laser of a drawing apparatus, and a predetermined resist pattern is drawn. The resist pattern includes an L / S pattern. Alternatively, the resist pattern is an L / S pattern. In this example, the resist pattern includes an unequal pitch L / S pattern in which the ratio a:b of the width a of the irradiated portion (if it is a positive resist instead of a negative resist, the non-irradiated portion) to the width b of the non-irradiated portion (if it is a positive resist, the irradiated portion) is 1:3.

[0051] In the first light-shielding film etching step (Step 5), as shown in FIG. 7(a), with the resist pattern as a mask for etching treatment, the exposed portion of the second light-shielding film 3B is removed by etching. The etching may be either dry etching or wet etching, but for a large-sized photomask, wet etching is preferred. As the etchant, an etching solution or an etching gas is used. Whichever etchant is used, an etchant having etching selectivity with respect to the second light-shielding film 3B (an etchant that does not etch the first light-shielding film 3A) is used, so that only the second light-shielding film 3B is selectively etched.

[0052] In the second drawing step (Step 8), similar to the first drawing step (Step 3), as shown in FIG. 8(a), the resist film 4 is irradiated with exposure light using an electron beam or a laser of a drawing apparatus, and a predetermined resist pattern is drawn. The drawing apparatus is the same apparatus as the one used in the first drawing step (Step 3). The resist pattern includes an L / S pattern. Alternatively, the resist pattern is an L / S pattern. In this example, the resist pattern is an unequal-spacing L / S pattern with a ratio a:b = 1:3 of the width a of the irradiated portion (if it is a positive resist instead of a negative resist, it is the non-irradiated portion) to the width b of the non-irradiated portion (if it is a positive resist, it is the irradiated portion), and the irradiated portion is located at the center in the width direction between adjacent lines formed by the second light-shielding film 3B and the lines formed by the second light-shielding film 3B are located at the center in the width direction of the non-irradiated portion.

[0053] In the second light-shielding film etching step (step 10), as shown in FIG. 8(c), with the resist pattern and the second light-shielding film 3B as etching masks, the exposed portion of the first light-shielding film 3A is removed by etching. The etching may be either dry etching or wet etching, but for a large-sized photomask, wet etching is preferred. As the etchant, an etching solution or an etching gas is used. Whichever etchant is used, an etchant having etching selectivity with respect to the first light-shielding film 3A (an etchant that does not etch the second light-shielding film 3B) is used, so that only the first light-shielding film 3A is selectively etched.

[0054] Thus, the method for manufacturing the photomask 1 according to this embodiment is a method of dividing the L / S pattern into two groups in line units so that adjacent lines are not included in the same group, and patterning each of the two types of light-shielding films 3A and 3B, which are formed corresponding to each group and have different etching characteristics from each other, so as to form the lines corresponding to the corresponding group.

[0055] Also, on this premise, the method for manufacturing the photomask 1 according to this embodiment includes: i) a photomask blank preparation step of preparing a photomask blank in which light-shielding films 3A and 3B corresponding to each group are laminated and formed on the surface of the transparent substrate 2; ii) a patterning step of patterning the light-shielding film 3B corresponding to one group so as to form the lines corresponding to the group; and iii) a patterning step of patterning the light-shielding film 3A corresponding to the other group so as to form the lines corresponding to the group.

[0056] Also, in the method for manufacturing the photomask 1 according to the present embodiment, two types of light-shielding films 3A and 3B having different etching characteristics are used, and an L / S pattern is formed by double patterning. For this reason, for example, even in a lithography apparatus where an equally spaced L / S pattern with a line width of 0.7 μm and a pitch of 1.4 μm is the limit of the lithography performance, by patterning each of the light-shielding films 3A and 3B with an L / S pattern where the line width:space width = a:b = 1:3 = 0.4 μm:1.2 μm, a fine equally spaced L / S pattern with a line width of 0.4 μm and a pitch of 0.8 μm can be formed.

[0057] <Embodiment 3> Hereinafter, Embodiment 3 of the present invention will be described with reference to FIGS. 9 to 14. In the following description, the points different from Embodiment 1 will be described, and the same points will be omitted as being the same as the description of Embodiment 1.

[0058] As shown in FIG. 9, the light-shielding film 3 includes a first light-shielding film 3A, a second light-shielding film 3B, and a third light-shielding film 3C. The L / S pattern is an L / S pattern in which the lines formed by the first light-shielding film 3A, the lines formed by the second light-shielding film 3B, and the lines formed by the third light-shielding film 3C are repeated with a space in between. The L / S pattern is an equally spaced L / S pattern in which the line and the space have the same width.

[0059] The first light-shielding film 3A, the second light-shielding film 3B, and the third light-shielding film 3C are each selected from different materials among Cr or Cr-based compounds, Ni or Ni-based compounds, Ti or Ti-based compounds, or Mo or Mo-based compounds. Thus, the first light-shielding film 3A, the second light-shielding film 3B, and the third light-shielding film 3C have different etching characteristics from each other due to their different materials. That is, the first light-shielding film 3A has etching selectivity with respect to the second light-shielding film 3B and the third light-shielding film 3C, the second light-shielding film 3B has etching selectivity with respect to the first light-shielding film 3A and the third light-shielding film 3C, and the third light-shielding film 3C has etching selectivity with respect to the first light-shielding film 3A and the second light-shielding film 3B.

[0060] As shown in FIGS. 10 to 14, the method for manufacturing the photomask 1 includes: i) a photomask blank preparation step (step 1), ii) a resist film formation step (step 2), iii) a drawing step (step 3), iv) a development step (step 4), v) a light-shielding film etching step (step 5), vi) a resist film removal step (step 6), vii) a light-shielding film formation step (step 7), viii) a resist film formation step (step 8), ix) a drawing step (step 9), x) a development step (step 10), xi) a light-shielding film etching step (step 11), xii) a resist film removal step (step 12), xiii) a light-shielding film formation step (step 13), xiv) a resist film formation step (step 14), xv) a drawing step (step 15), xvi) a development step (step 16), xvii) a light-shielding film etching step (step 17), xviii) a resist film removal step (step 18). The resist film formation step (step 2) to the resist film removal step (step 6), the resist film formation step (step 8) to the resist film removal step (step 12), and the resist film formation step (step 14) to the resist film removal step (step 18) are each referred to as a patterning step.

[0061] In the first drawing step (step 3), as shown in FIG. 10(c), the resist film 4 is irradiated with exposure light using an electron beam or a laser of a drawing apparatus, and a predetermined resist pattern is drawn. The resist pattern includes an L / S pattern. Alternatively, the resist pattern is an L / S pattern. In this example, the resist pattern includes an uneven pitch L / S pattern with a ratio c:d = 1:5 between the width c of the irradiated portion (if it is a positive resist instead of a negative resist, it is the non-irradiated portion) and the width d of the non-irradiated portion (if it is a positive resist, it is the irradiated portion). Note that d = 5 is the value when the width of the line = the width of the space in d = 2 × the width of the line (= c) + 3 × the width of the space.

[0062] In the second and third drawing steps (steps 9 and 15), as in the first drawing step (step 3), as shown in FIGS. 12(a) and 13(c), the resist film 4 is irradiated with exposure light using an electron beam or a laser of a drawing apparatus, and a predetermined resist pattern is drawn. The drawing apparatus is the same apparatus as the drawing apparatus used in the first drawing step (step 3). The resist pattern includes an L / S pattern. Alternatively, the resist pattern is an L / S pattern. In this example, the resist pattern is an uneven pitch L / S pattern with a ratio c:d = 1:5 of the width c of the irradiated portion (if it is a positive resist instead of a negative resist, the non-irradiated portion) to the width d of the non-irradiated portion (if it is a positive resist, the irradiated portion), and the irradiated portion is located between adjacent lines formed by the first light-shielding film 3A and the lines formed by the first light-shielding film 3A are located in the non-irradiated portion.

[0063] In the second light-shielding film forming step (step 13), as shown in FIG. 13(a), a third light-shielding film 3C is formed on the entire surfaces of the transparent substrate 2, the first light-shielding film 3A, and the second light-shielding film 3B. The third light-shielding film 3C is formed by a sputtering method, an evaporation method, or the like. The film thickness of the third light-shielding film 3C is the same as the film thickness of the first light-shielding film 3A. Alternatively, the film thickness of the third light-shielding film 3C may be larger or smaller than the film thickness of the first light-shielding film 3A.

[0064] In the third light-shielding film etching step (step 17), as shown in FIG. 14(a), using the resist pattern as a mask for etching treatment, the exposed portion of the third light-shielding film 3C is removed by etching. The etching may be either dry etching or wet etching, but for a large-sized photomask, wet etching is preferred. An etchant, such as an etching solution or an etching gas, is used. Whichever etchant is used, an etchant having etching selectivity for the third light-shielding film 3C (an etchant that does not etch the first light-shielding film 3A and the second light-shielding film 3B) is used, so that only the third light-shielding film 3C is selectively etched.

[0065] Thus, the method for manufacturing the photomask 1 according to this embodiment is a method of dividing the L / S pattern into three groups in line units so that adjacent lines are not included in the same group, and patterning each of the three light-shielding films 3A, 3B, and 3C, which are formed corresponding to each group and have different etching characteristics from each other, so as to form the lines corresponding to the corresponding group.

[0066] Also, on this premise, the method for manufacturing the photomask 1 according to this embodiment includes: i) a photomask blank preparation step of preparing a photomask blank in which a light-shielding film 3A corresponding to one group is formed on the surface of the transparent substrate 2; ii) a patterning step of patterning the light-shielding film 3A corresponding to one group so as to form the lines corresponding to the group; iii) a light-shielding film formation step of forming a light-shielding film 3B corresponding to another group; iv) a patterning step of patterning the light-shielding film 3B corresponding to another group so as to form the lines corresponding to the group; v) a light-shielding film formation step of forming a light-shielding film 3C corresponding to still another group; and vi) a patterning step of patterning the light-shielding film 3C corresponding to still another group so as to form the lines corresponding to the group.

[0067] Alternatively, the method for manufacturing the photomask 1 according to this embodiment can also adopt the same method as the method for manufacturing the photomask 1 according to Embodiment 2. In this case, the method for manufacturing the photomask 1 according to this embodiment includes: i) a photomask blank preparation step of preparing a photomask blank in which light-shielding films 3A, 3B, and 3C corresponding to each group are laminated and formed on the surface of the transparent substrate 2; ii) a patterning step of patterning the light-shielding film 3C corresponding to one group so as to form the lines corresponding to the group; iii) a patterning step of patterning the light-shielding film 3B corresponding to another group so as to form the lines corresponding to the group; and iv) a patterning step of patterning the light-shielding film 3A corresponding to still another group so as to form the lines corresponding to the group.

[0068] According to the method for manufacturing the photomask 1 according to the present embodiment, three types of light-shielding films 3A, 3B, and 3C with different etching characteristics are used, and an L / S pattern is formed by triple patterning. Therefore, for example, even in a lithography apparatus where an equally spaced L / S pattern with a line width of 0.7 μm and a pitch of 1.4 μm is at the limit of lithography performance, by patterning each of the light-shielding films 3A, 3B, and 3C with an L / S pattern where the line width:space width = c:d = 1:5 = 0.3 μm:1.5 μm, a finer equally spaced L / S pattern with a line width of 0.3 μm and a pitch of 0.6 μm can be formed.

[0069] <Embodiment 4> Hereinafter, Embodiment 4 of the present invention will be described with reference to FIGS. 15 to 18. In the following, the differences from Embodiment 1 will be described, and the same points will be omitted as being the same as the description of Embodiment 1.

[0070] As shown in FIG. 15, the photomask 1 is a photomask having a hole pattern. The hole pattern is a hole pattern in which holes of a rectangle (square or rectangle) with all four corners equal are two-dimensionally arranged. The light-shielding film 3 includes a first light-shielding film 3A with an equally spaced L / S pattern and a second light-shielding film 3B with an equally spaced L / S pattern and arranged orthogonally to the first light-shielding film 3A. As a result, for each hole, two parallel opposite sides are formed by the edge of the first light-shielding film 3A (the line), and the other pair of parallel opposite sides are formed by the edge of the second light-shielding film 3B (the line).

[0071] As shown in FIGS. 16 to 18, the method for manufacturing the photomask 1 includes: i) a photomask blank preparation step (step 1), ii) a resist film formation step (step 2), iii) a drawing step (step 3), iv) a development step (step 4), v) a light-shielding film etching step (step 5), vi) a resist film removal step (step 6), vii) a light-shielding film formation step (step 7), viii) a resist film formation step (step 8), ix) a drawing step (step 9), x) a development step (step 10), xi) a light-shielding film etching step (step 11), and xii) a resist film removal step (step 12). Note that, from the resist film formation step (step 2) to the resist film removal step (step 6), and from the resist film formation step (step 8) to the resist film removal step (step 12) are each referred to as a patterning step.

[0072] The method for manufacturing the photomask 1 is the same as the method for manufacturing the photomask 1 according to Embodiment 1, except that the size of the L / S pattern is different and the orientation of the photomask blank is changed by 90 degrees (from one of the directions X and Y to the other) before performing the second drawing step (step 9).

[0073] In the first and second drawing steps (steps 3 and 9), as shown in FIGS. 16(c) and 18(a), the resist film 4 is irradiated with exposure light using an electron beam or a laser of a drawing apparatus, and a predetermined resist pattern is drawn. The resist pattern includes an L / S pattern. Alternatively, the resist pattern is an L / S pattern. In this example, the resist pattern includes an equally spaced L / S pattern in which the ratio of the width of the irradiated portion (if it is a positive resist instead of a negative resist, the non-irradiated portion) to the width of the non-irradiated portion (if it is a positive resist, the irradiated portion) = 1:1.

[0074] In any step after the first drawing step (step 3) and before the second drawing step (step 9), the orientation (angular position around the vertical axis) of the photomask blank around the vertical axis is changed by 90 degrees. Thereby, the L / S pattern of the first light-shielding film 3A and the L / S pattern of the second light-shielding film 3B are orthogonal to each other, and a rectangular hole is formed.

[0075] Thus, the method for manufacturing the photomask 1 according to this embodiment is a method of dividing a hole pattern into a plurality of groups by side, such that adjacent sides are not included in the same group, and patterning each of two types of light-shielding films 3A and 3B, which are respectively formed corresponding to each group and have different etching characteristics, so as to form the sides corresponding to the corresponding group.

[0076] Also, on this premise, the method for manufacturing the photomask 1 according to this embodiment includes: i) a photomask blank preparation step of preparing a photomask blank in which a light-shielding film 3A corresponding to one group is formed on the surface of a transparent substrate 2; ii) a patterning step of patterning the light-shielding film 3A corresponding to one group so as to form the sides corresponding to the group; iii) a light-shielding film formation step of forming a light-shielding film 3B corresponding to another group; and iv) a patterning step of patterning the light-shielding film 3B corresponding to another group so as to form the sides corresponding to the group.

[0077] Alternatively, the method for manufacturing the photomask 1 according to this embodiment can also adopt the same method as the method for manufacturing the photomask 1 according to Embodiment 2. In this case, the method for manufacturing the photomask 1 according to this embodiment includes: i) a photomask blank preparation step of preparing a photomask blank in which light-shielding films 3A and 3B corresponding to each group are laminated and formed on the surface of a transparent substrate 2; ii) a patterning step of patterning the light-shielding film 3B corresponding to one group so as to form the sides corresponding to the group; and iii) a patterning step of patterning the light-shielding film 3A corresponding to another group so as to form the sides corresponding to the group.

[0078] According to the method for manufacturing the photomask 1 according to this embodiment, two types of light-shielding films 3A and 3B having different etching characteristics are used, and adjacent sides of the hole pattern are separately formed by double patterning. As a result, the corners of the rectangular holes are formed sharply without rounding. For this reason, even in a lithography apparatus where, for example, a 1.0 μm square hole pattern is at the limit of the drawing performance due to the beam diameter of the electron beam or laser, by patterning each of the light-shielding films 3A and 3B with an L / S pattern having a line width of 0.8 μm and a pitch of 1.6 μm, a fine 0.8 μm square hole pattern can be formed.

[0079] Also, according to the method for manufacturing the photomask 1 according to this embodiment, the edge of the first light-shielding film 3A (of the line) is formed along the scanning direction of the electron beam or laser, and by performing the second drawing step (step 9) after changing the orientation of the photomask blank by 90 degrees, the edge of the second light-shielding film 3B (of the line) is also formed along the scanning direction of the electron beam or laser. For this reason, each side of the hole pattern can be formed as a clean straight line with the same accuracy.

[0080] However, double patterning may be performed without changing the orientation of the photomask blank. In this case, the edge of one of the first light-shielding film 3A or the second light-shielding film 3B (of the line) is formed along a direction orthogonal to the scanning direction of the electron beam or laser.

[0081] Note that the density, number, and size of the holes in the hole pattern can be set as appropriate. The example shown in FIG. 19 is an example in which the density of the holes is smaller than the example shown in FIG. 15.

[0082] <Embodiment 5> FIG. 20 shows Embodiment 5 of the present invention. The difference from Embodiment 4 is that the intersection angle between the L / S pattern of the first light-shielding film 3A and the L / S pattern of the second light-shielding film 3B is not a right angle but an acute angle, and thus the shape of the hole becomes a rhombus or a parallelogram. Other than this, it is the same as Embodiment 4. The direction of the photomask blank is also changed (from one of Direction P and Direction Q to the other) so that the edges of each of the first light-shielding film 3A and the second light-shielding film 3B (of the lines) are formed along the scanning direction of the electron beam or the laser. Regarding the same points, the description is omitted on the assumption that it is the same as the description for Embodiments 1 and 4.

[0083] Note that the density, number, and size of the holes in the hole pattern can be set as appropriate. The example shown in FIG. 21 is an example with a smaller hole density than the example shown in FIG. 20.

[0084] <Embodiment 6> FIG. 22 shows Embodiment 6 of the present invention. The difference from Embodiment 1 is that the L / S pattern is not a straight line but a curve. In this example, the curve is a circular line or an arc line. Other than this, it is the same as Embodiment 1. Regarding the same points, the description is omitted on the assumption that it is the same as the description for Embodiment 1.

[0085] Also, the method for manufacturing the photomask 1 can adopt the same method as the method for manufacturing the photomask 1 according to Embodiment 2, similar to Embodiments 3 to 5.

[0086] <Example> In each of the above embodiments, the film is a light-shielding film. In addition to this, various combinations of films shown in Table 1 below can be adopted.

Table 1

[0087] Note that the present invention is not limited to the above embodiments, and various modifications are possible without departing from the gist of the present invention.

[0088] In the above-described Embodiments 1 to 3 and 6, the L / S pattern of the photomask 1 is an equally spaced L / S pattern. However, the present invention is not limited thereto. The L / S pattern may be an unequally spaced L / S pattern in which the width of the space is larger than that of the line or vice versa.

[0089] Also, in the above-described Embodiments 4 and 5, the hole pattern is a square hole. However, the present invention is not limited thereto. The polygonal hole pattern may be another polygon such as a triangle or a hexagon.

[0090] Moreover, as long as there is no physical interference, it is naturally possible to apply the above-described technical elements to other embodiments or examples, replace the above-described technical elements with technical elements related to other embodiments or examples, combine the above-described technical elements with each other, etc., which is what the present invention naturally intends.

Description of Reference Numerals

[0091] 1... photomask, 2... transparent substrate, 3... light-shielding film, 3A... first light-shielding film, 3B... second light-shielding film, 3C... third light-shielding film, 4... resist film, 4a... unnecessary portion

Claims

A method for manufacturing a photomask having a line-and-space pattern composed of at least one type of film selected from a light-shielding film, a semi-transmissive film, and a phase shift film, comprising: dividing the line-and-space pattern into a plurality of groups in line units so that adjacent lines are not included in the same group; pattern-forming each of a plurality of types of films that are respectively formed corresponding to each group and have different etching characteristics from each other so as to form lines corresponding to the corresponding group; In the method for manufacturing a photomask, a photomask blank preparation step of preparing a photomask blank having a film corresponding to one group formed on the surface of a transparent substrate; a patterning step of patterning the film corresponding to one group so as to form lines corresponding to the group; a film formation step of forming a film corresponding to another group; and a patterning step of patterning the film corresponding to another group so as to form lines corresponding to the group, in this order. A method for manufacturing a photomask. A method for manufacturing a photomask having a line-and-space pattern composed of at least one type of film selected from a light-shielding film, a semi-transmissive film, and a phase shift film, wherein each line is only a light-shielding portion, each line is only a semi-transmissive portion, or each line is only a phase shift portion, comprising: dividing the line-and-space pattern into a plurality of groups in line units so that adjacent lines are not included in the same group; pattern-forming each of a plurality of types of films that are respectively formed corresponding to each group and have different etching characteristics from each other so as to form lines corresponding to the corresponding group; In the method for manufacturing a photomask, a photomask blank preparation step of preparing a photomask blank having films corresponding to each group laminated on the surface of a transparent substrate; a patterning step of patterning the film corresponding to one group so as to form lines corresponding to the group; and a patterning step of patterning the film corresponding to another group so as to form lines corresponding to the group. A method for manufacturing a photomask. Enabling the manufacture of a photomask having a line-and-space pattern with a pitch smaller than the limit of the drawing performance of the drawing apparatus used in the patterning step The method for manufacturing a photomask according to claim 1 or claim 2. To enable the production of a photomask having a line-and-space pattern with a pitch of 0.8 μm or less The method for manufacturing a photomask according to claim 1 or claim 2.

5. A method for manufacturing a photomask having a polygonal hole pattern formed using at least one type of film selected from a light-shielding film, a semi-transmissive film, and a phase shift film, dividing the hole pattern into a plurality of groups by side so that adjacent sides are not included in the same group, pattern each of a plurality of types of films that are respectively formed corresponding to each group and have different etching characteristics from each other so as to form the sides related to the corresponding group, The method for manufacturing a photomask.

6. A photomask blank preparation step of preparing a photomask blank having a film corresponding to one group formed on the surface of a transparent substrate, A patterning step of patterning the film corresponding to one group so as to form the sides related to the group, A film formation step of forming a film corresponding to another group, comprising a patterning step of patterning the film corresponding to another group so as to form the sides related to the group. The method for manufacturing a photomask according to claim 5.

7. A photomask blank preparation step of preparing a photomask blank having films corresponding to each group laminated on the surface of a transparent substrate, A patterning step of patterning the film corresponding to one group so as to form the sides related to the group, comprising a patterning step of patterning the film corresponding to another group so as to form the sides related to the group. The method for manufacturing a photomask according to claim 5.

8. further comprising an orientation change step of changing the orientation of the photomask blank so that each side is formed along the scanning direction of drawing in each patterning step. The method for manufacturing a photomask according to claim 6 or claim 7.

9. A photomask having a line-and-space pattern formed using at least one type of film selected from a light-shielding film, a semi-transmissive film, and a phase shift film, wherein each line is only a light-shielding portion, each line is only a semi-transmissive portion, or each line is only a phase shift portion, and each line is formed of a film having different etching characteristics from an adjacent line. The photomask. A photomask having a line and space pattern with a pitch smaller than the limit of the drawing performance of a drawing apparatus used in a patterning process The photomask according to claim 9. A photomask having a line and space pattern with a pitch of 0.8 μm or less The photomask according to claim 9.

12. A photomask having a polygonal hole pattern formed using at least one type of film selected from a light-shielding film, a semi-transmissive film, and a phase shift film, wherein each side is formed by an edge of a film having etching characteristics different from those of an adjacent side The photomask.

Images