Method for manufacturing a multi-tone photomask and multi-tone photomask

Abstract

The present invention provides a manufacturing method of a multi-tone photomask capable of being aligned without alignment and a multi-tone photomask. The manufacturing method of a multi-tone photomask includes: a step of preparing an intermediate body, the intermediate body being composed of a layer-structured film, the intermediate body having: a semi-transparent film 3 laminated on a transparent substrate 2; an intermediate film 4 having different etching characteristics from the semi-transparent film 3, laminated on the semi-transparent film 3 in a manner of being overlapped; a light-blocking film 5 having the same etching characteristics as the semi-transparent film 3, laminated on the intermediate film 4 in a manner of exposing at least a part of a peripheral area of the intermediate film 4; and at least a part of the exposed part of the intermediate film 4 having a shape expanding outward as closer to the edge 4a of the transparent substrate 2; a step of etching the exposed part of the intermediate film 4 in multiple times and finally removing; and a step of performing plasma treatment on the exposed part of the semi-transparent film 3 after each etching except the last time or including the last time, changing the transmittance of the part.

Description

TECHNICAL FIELD

[0001] The present application relates to a manufacturing method of a multi-tone photomask having a gradual change portion and a multi-tone photomask. BACKGROUND

[0002] The multi-tone photomask realizes a multi-tone (three or more tones) of combining two tones of a white tone of the transmissive portion and a black tone of the light-shielding portion, and an intermediate (gray tone) tone of white and black of the semi-transmissive portion, because it includes a semi-transmissive portion having a transmittance between a transmittance of the transmissive portion and a transmittance of the light-shielding portion. By using the multi-tone photomask, it is possible to form a pattern of different exposure amounts in a photoresist with one exposure. Therefore, it is possible to realize reduction in the number of uses of a photomask, reduction in manufacturing processes, and further reduction in manufacturing cost.

[0003] A gradual change mask is one of the multi-tone photomasks. The gradual change mask is a photomask including a gradual change portion (Patent Literature 1). The gradual change portion is constituted of a plurality of regions having different transmittances. More specifically, the gradual change portion is provided in a boundary region between the semi-transmissive portion and the transmissive portion in the semi-transmissive portion, and is constituted of a plurality of regions whose transmittances stepwise increase toward the boundary between the semi-transmissive portion and the transmissive portion.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1 Japanese Patent Application Laid-Open No. 2011-209759 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] The manufacturing method of the conventional gradual change mask requires at least two times of drawing processes, that is, a drawing process (exposure process) of a pattern constituting the light-shielding portion and a drawing process of a pattern constituting the semi-transmissive portion. Moreover, if the drawing processes are multiple times, it is easy to cause a positional shift (alignment shift) of the patterns formed in each process.

[0009] As a countermeasure, there is a use of an alignment mark. In the drawing process after the second time, alignment (positioning) is performed by reading the alignment mark. However, even if the alignment mark is used, it is not possible to completely eliminate the alignment shift, and at the maximum, an alignment shift of 500 nm occurs. Therefore, it leads to a situation where it is difficult to perform high refinement of the multi-tone photomask.

[0010] Therefore, the present application is completed in view of the above-described situation, and an object thereof is to provide a manufacturing method of a multi-tone photomask and a multi-tone photomask which do not have an alignment shift and can realize high refinement of the multi-tone photomask.

[0011] MEANS FOR SOLVING THE PROBLEMS

[0012] A manufacturing method of a multi-tone photomask of the present invention is a manufacturing method of a multi-tone photomask including a transmissive portion, a semi-transmissive portion, and an opaque portion, and including a gradual change portion in the semi-transmissive portion, the gradual change portion being composed of a plurality of regions in which transmittance is stepwise increased toward a boundary between the semi-transmissive portion and the transmissive portion;

[0013] The manufacturing method of the multi-tone photomask includes:

[0014] An intermediate body preparation step prepares an intermediate body composed of a laminated film structure in which the intermediate body has: a semi-transparent film having a prescribed pattern shape and laminated on a transparent substrate; an intermediate film having etching characteristics different from those of the semi-transparent film and laminated so as to overlap the semi-transparent film; and an opaque film having a prescribed pattern shape and the same etching characteristics as those of the semi-transparent film and laminated so as to expose at least a part of a peripheral region of the intermediate film, at least a part of the exposed part of the intermediate film having a shape that expands outward more as it approaches an edge of the transparent substrate;

[0015] An intermediate film etching step etches the exposed part of the intermediate film in multiple stages and finally removes it;

[0016] A plasma treatment step performs plasma treatment on the exposed part of the semi-transparent film after each of the multiple etching stages except the last stage or including the last stage, to change the transmittance of the part.

[0017] Further, a multi-tone photomask of the present invention includes:

[0018] a semi-transparent film having a prescribed pattern shape and laminated on a transparent substrate;

[0019] an intermediate film having etching characteristics different from those of the semi-transparent film and laminated so as to expose at least a part of a peripheral region of the semi-transparent film;

[0020] an opaque film having a prescribed pattern shape and the same etching characteristics as those of the semi-transparent film and laminated so as to overlap the intermediate film;

[0021] at least a part of the exposed part of the semi-transparent film includes a gradual change portion composed of a plurality of regions in which transmittance is stepwise increased toward an edge of the semi-transparent film.

[0022] Here, as one mode of the manufacturing method of the multi-tone photomask of the present invention, the following mode can be employed:

[0023] The intermediate body preparation step includes an intermediate body manufacturing step of manufacturing the intermediate body, and the intermediate body manufacturing step includes:

[0024] an etching resist film formation step of forming an etching resist film on a surface of the photomask blank;

[0025] resist pattern formation step of forming a prescribed resist pattern;

[0026] light shielding film etching step of etching and removing the exposed portion of the light shielding film using the resist pattern as a mask;

[0027] shaping step of alternately repeating intermediate film surface etching of etching and removing a prescribed depth in the film thickness direction of the exposed portion of the intermediate film using the light shielding film as a mask and light shielding film side etching of etching and removing a prescribed depth in the inside direction from the end surface of the exposed edge in the light shielding film, and shaping the exposed portion of the intermediate film into a shape in which the edge of the transparent substrate is expanded outward more as it is closer to the edge of the transparent substrate;

[0028] semi-permeable film etching step of etching and removing the exposed portion of the semi-permeable film using the intermediate film as a mask;

[0029] resist film removing step of removing the resist film.

[0030] Further, in this case, a method in which the portion of the intermediate film is shaped into a stepped shape in the shaping step can be employed.

[0031] Further, as another embodiment of the method of manufacturing a multi-tone photomask of the present application, a method in which the number of times of intermediate film surface etching and light shielding film side etching is set according to the number of tones of the gradual change portion can be employed.

[0032] Further, as another embodiment of the method of manufacturing a multi-tone photomask of the present application, a method in which the etching amount of each intermediate film surface etching is set so that the total of the etching amounts of the intermediate film surface etchings is the same as or greater than the film thickness of the intermediate film can be employed.

[0033] Further, as still another embodiment of the method of manufacturing a multi-tone photomask of the present application, a method in which the etching amount of each light shielding film side etching is set according to the gradient of the transmittance of the gradual change portion can be employed.

[0034] Further, as still another embodiment of the method of manufacturing a multi-tone photomask of the present application, a method in which the position of the edge of the portion of the resist pattern corresponding to the gradual change portion is a position offset outward by a value that is the total of the film thicknesses of the semi-permeable film, the intermediate film, and the light shielding film or a value greater than the total, with respect to the position of the edge of the semi-permeable film after the semi-permeable film etching step can be employed.

[0035] Further, as still another embodiment of the method of manufacturing a multi-tone photomask of the present application, a method in which a film having a lower etching rate than the semi-permeable film and the light shielding film is selected as the intermediate film can be employed.

[0036] Furthermore, as another embodiment of the manufacturing method of the multi-tone photomask of the present invention, the following method can be adopted: the number of times the intermediate film is etched and plasma treated is set according to the number of hues in the gradient section.

[0037] Furthermore, as another embodiment of the method for manufacturing the multi-tone photomask of the present invention, the processing time of each plasma process can be set according to the transmittance gradient of the gradient section.

[0038] Furthermore, as one embodiment of the multi-tone light mask of the present invention, the following structure can be adopted: by bringing the edge of the intermediate film into a position that is more inward than the edge of the light-shielding film, a cut bottom without the intermediate film is formed below the edge of the light-shielding film, thereby causing the end of the light-shielding film to be overhanging and becoming a protruding end.

[0039] Furthermore, as another embodiment of the multi-tone photomask of the present invention, a structure can be adopted in which the thickness of the intermediate film is 90 nm or more and 200 nm or less.

[0040] Invention Effects

[0041] According to the present invention, only one drawing process is required. Therefore, no alignment is required during the manufacturing process of multi-tone photomasks. Thus, according to the present invention, alignment deviations can be eliminated, achieving high precision in multi-tone photomasks. Attached Figure Description

[0042] Figure 1 This is an enlarged cross-sectional view of the main part of a multi-tone light mask according to one embodiment of the present invention.

[0043] Figure 2 (a) to (d) are illustrations of the manufacturing method of multi-color light masks.

[0044] Figure 3 (a) to (d) are following Figure 2 Explanatory diagram.

[0045] Figure 4 (a) to (d) are following Figure 3 Explanatory diagram.

[0046] Figure 5 (a) to (d) are following Figure 4 Explanatory diagram.

[0047] Figure 6 (a) to (c) are following Figure 5 Explanatory diagram.

[0048] Figure 7 (a) to (c) are explanatory diagrams of the plasma irradiation time in the plasma treatment process.

[0049] Figure 8 Fig. 2 is an explanatory view showing the relationship between the edge position of the semi- transparent film and the edge position of the resist film.

[0050] Figure 9 Fig. 3 is an explanatory view showing the relationship between the edge position of the light-shielding film and the edge position of the resist film.

[0051] Figure 10 Fig. 4 is an explanatory view showing the relationship between the stepped edge position of the light- shielding film and the boundary position of the gradual change portion.

[0052] Figure 11 Figs. 5 (a) and (b) are explanatory views of the transmittance gradient with respect to the gradual change portion.

[0053] Figure 12 Figs. 6 (a) and (b) are explanatory views showing the relationship between the edge position of the light- shielding film and the edge position of the intermediate film.

[0054] Figure 13 Fig. 7 (a) is an enlarged sectional view of a main portion of a multi-tone photomask of island type (convex type), and Fig. 7 (b) is an enlarged sectional view of a main portion of a multi-tone photomask of hole type (concave type).

[0055] Figure 14 Figs. 8 (a) to (d) are explanatory views of another manufacturing method of a multi-tone photomask.

[0056] Figure 15 Figs. 9 (a) to (d) are explanatory views of another manufacturing method of a multi-tone photomask. Figure 14

[0057] Figs. 10 (a) to (d) are explanatory views of another manufacturing method of a multi-tone photomask. Figure 16

[0058] Figs. 11 (a) to (d) are explanatory views of another manufacturing method of a multi-tone photomask. Figure 17 Figure 16 Figs. 12 (a) to (d) are explanatory views of another manufacturing method of a multi-tone photomask.

[0059] Symbol explanation

[0060] 1: Multi-tone photomask; 1A: Pattern; 2: Transparent substrate; 20: Transmissive portion; 3: Semi- transparent film; 3a: Edge; 3b: Boundary; 3c: Boundary; 3d: Portion; 30: Semi-transmissive portion, 31: Gradual change portion; 31A: Outermost portion; 31B: Intermediate portion; 31C: Innermost portion; 4: Intermediate film (etching stop film); 4a: Edge; 4b: Bottomed portion; 4c: Portion (surface portion); 4d: Lower section portion; 4e: Middle section portion; 4f: Upper section portion; 5: Light-shielding film; 5a: Edge; 5b: Projecting end portion; 5c: Portion; 5d: Portion; 50: Light-shielding portion; 6: Resist film; 6a: Edge; 6b: Remaining portion. DETAILED DESCRIPTION ​

[0061] First, the structure of a multi-tone photomask according to one embodiment of the present invention will be described.

[0062] like Figure 1 As shown, the multi-tone photomask 1 is a gradient mask including a transmissive portion 20, a semi-transmissive portion 30, and a light-shielding portion 50, with a gradient portion 31 included in the semi-transmissive portion 30. The gradient portion 31 includes multiple regions whose transmittance increases in a stepped manner towards the boundary between the semi-transmissive portion 30 and the transmissive portion 20 (towards the edge 3a of the semi-transmissive membrane 3). In this embodiment, the gradient portion 31 includes three regions (three hues) from the light-shielding portion 50 towards the transmissive portion 20, namely the innermost 31C, a middle portion 31B, and the outermost 31A. Therefore, in this embodiment, the multi-tone photomask 1 has five hues.

[0063] The multi-tone photomask 1 is manufactured from a photomask blank on a transparent substrate 2 by sequentially stacking a semi-permeable film 3, an intermediate film (etch stop film) 4, and a light-shielding film 5. Since the semi-permeable film 3 is located at the bottom layer, this photomask blank is called a bottom type.

[0064] In the photomask blank, a semi-permeable film 3 is formed on a transparent substrate 2 by sputtering, evaporation, or other methods. The thickness of the semi-permeable film 3 is, for example, in the range of 10 nm to 50 nm. An intermediate film 4 is formed on the semi-permeable film 3 by sputtering, evaporation, or other methods. The thickness of the intermediate film 4 is, for example, in the range of 90 nm to 200 nm. The reason for this will be explained later. A light-shielding film 5 is formed on the intermediate film 4 by sputtering, evaporation, or other methods. The thickness of the light-shielding film 5 is, for example, in the range of 50 nm to 120 nm.

[0065] The transparent substrate 2 is a substrate made of synthetic quartz glass or the like. The transparent substrate 2 has a transmittance of 95% or more for the representative wavelengths (e.g., i-lines, h-lines, or g-lines) contained in the exposure light used in the drawing process using the multi-tone photomask 1. Furthermore, the exposure light can be, for example, i-lines, h-lines, or g-lines, or it can be a mixture of at least two of these lights. However, the exposure light is not limited to these.

[0066] The semi-permeable membrane 3 uses a Cr-based material, such as Cr or Cr-based compounds, Ni or Ni-based compounds, Ti or Ti-based compounds, Si-based compounds, or metal silicide compounds. In this embodiment, the semi-permeable membrane 3 uses a Cr-based compound. The semi-permeable membrane 3 is a halftone film. Alternatively, the semi-permeable membrane 3 may also be a phase-shifting film. The semi-permeable membrane 3 is configured to have a transmittance of 10% to 70% relative to the representative wavelength contained in the exposure light, which is lower than that of the transparent substrate 2 and higher than that of the light-shielding film 5.

[0067] The intermediate film 4 is made of a non-Cr based material. In this embodiment, the intermediate film 4 is made of Ni, Ti, or a molybdenum silicide compound.

[0068] The light shielding film 5 uses the same material as the semi-permeable film 3. In the present embodiment, the light shielding film 5 uses a Cr-based compound. The light shielding film 5 has a transmittance of 1% or less with respect to a representative wavelength included in the exposure light. Alternatively, even if the transmittance of the light shielding film 5 is higher than 1%, as long as the laminated transmittance of the light shielding portion 50 is 1% or less. Alternatively, as long as the optical density (OD value) of the light shielding portion 50 satisfies 2.7 or more.

[0069] The semi-permeable film 3 and the light shielding film 5 have the same etching characteristics because they use the same material. However, the semi-permeable film 3 and the light shielding film 5 have different etching characteristics because of the material and the intermediate film 4. That is, the semi-permeable film 3 and the light shielding film 5 have etching selectivity with respect to the intermediate film 4, and the intermediate film 4 has etching selectivity with respect to the semi-permeable film 3 and the light shielding film 5.

[0070] The light shielding portion 50 corresponds to a region left without removing the semi-permeable film 3, the intermediate film 4, and the light shielding film 5, that is, a region of the light shielding film 5 up to the edge 5a where the light shielding film 5 exists. The semi-transmissive portion 30 is provided between the light shielding portion 50 and the transmissive portion 20. The semi-transmissive portion 30 corresponds to a region where the semi-permeable film 3 is exposed by removing the intermediate film 4 and the light shielding film 5 from the photomask blank, that is, a region of the semi-permeable film 3 from the edge 5a of the light shielding film 5 to the edge 3a of the semi-permeable film 3 where the semi-permeable film 3 is exposed. The transmissive portion 20 corresponds to a region where the transparent substrate 2 is exposed by removing the semi-permeable film 3, the intermediate film 4, and the light shielding film 5 from the photomask blank, that is, a region of the semi-permeable film 3 from the edge 3a where the semi-permeable film 3 is exposed to the transparent substrate 2.

[0071] The gradual change portion 31 is provided in the entire region of the semi-transmissive portion 30. The innermost portion 31C of the gradual change portion 31 corresponds to a region located at the innermost side and in contact with the light shielding portion 50, that is, a region from the edge 5a of the light shielding film 5 to the boundary 3c inside the semi-permeable film 3. The intermediate portion 31B of the gradual change portion 31 corresponds to a region between the innermost portion 31C and the outermost portion 31A of the gradual change portion 31, that is, a region from the boundary 3c to the boundary 3b inside the semi-permeable film 3. The outermost portion 31A of the gradual change portion 31 corresponds to a region located at the outermost side and in contact with the transmissive portion 20, that is, a region from the boundary 3b inside the semi-permeable film 3 to the edge 3a of the semi-permeable film 3. In the present embodiment, since the gradual change portion 31 is three-tone, the intermediate portion 31B is one. However, in the case where the gradual change portion 31 is four-tone, the intermediate portion 31B is provided with two, and if the number of tones of the gradual change portion 31 is n, the number of the intermediate portion 31B is n-2.

[0072] The edge 4a of the intermediate film 4 is more inward than the edge 5a of the light shielding film 5, and the lower portion of the edge 5a of the light shielding film 5 becomes a cutout portion 4b where the intermediate film 4 does not exist. Moreover, in conjunction therewith, the end portion of the light shielding film 5 overhangs to become a protruding end portion 5b.

[0073] Although not shown, however Figure 1 The illustrated laminated film structure is also disposed bilaterally symmetrically on the opposite side in a state where the light shielding film 5 has a prescribed width. Also, one pattern 1A is constituted by the light shielding portion 50 and the semi-transmissive portions 30, 30 (the gradual change portions 31, 31) on both sides.

[0074] Next, a manufacturing method of the multi-tone photomask 1 of one embodiment of the present application will be described.

[0075] The manufacturing method of the multi-tone photomask 1 includes: i) a resist film forming step (step 1); ii) a drawing step (step 2); iii) a developing step (step 3); iv) a light shielding film etching step (step 4); v) an intermediate film surface etching step (step 5); vi) a light shielding film side etching step (step 6); vii) a semi-transmissive film etching step (step 7); viii) a resist film removing step (step 8); ix) an intermediate film divided etching step (step 9); and x) a plasma treatment step (step 10). Among these, the drawing step (step 2) and the developing step (step 3) are collectively referred to as a resist pattern forming step, and the intermediate film surface etching step (step 5) and the light shielding film side etching step (step 6) are collectively referred to as a shaping step.

[0076] In the resist film forming step (step 1), as shown in Figure 2 (a), a resist is uniformly applied to the surface of a photomask blank, thereby forming a resist film 6. The resist is applied by a coating method or a spraying method.

[0077] In the drawing step (step 2), as shown in Figure 2 (b), an electron beam or a laser of a drawing device (exposure device) is used to irradiate exposure light to the surface of the resist film 6, thereby drawing a prescribed resist pattern. The method of considering the design of the resist pattern (the position of the edge 6a of the resist film 6) will be described later. In the developing step (step 3), as shown in Figure 2 (c), the remaining portion 6b of the resist film 6 is removed, thereby forming a resist pattern. The developing is performed by immersion in a developing solution.

[0078] In the light shielding film etching step (step 4), as shown in Figure 2 (d), the exposed portion 5c of the light shielding film 5 is etched and removed using the resist pattern as a mask for etching treatment. The etching can be either of a dry etching or a wet etching, but if it is a large-sized photomask, the wet etching is preferable. An etchant is an etching liquid or an etching gas. Regardless of which etchant is used, since an etchant having etching selectivity to the light shielding film 5 (an etchant that does not etch the intermediate film 4) is used, only the light shielding film 5 is selectively etched.

[0079] In addition, in the light shielding film etching process (process 4), in order not to leave the unetched light shielding film 5 on the surface of the intermediate film 4, so-called over-etching in which the etching amount is additionally increased to the film thickness of the light shielding film 5 is performed.

[0080] In the intermediate film surface etching process (process 5), as shown in Figure 3 (a), the surface of the intermediate film 4 is etched and removed from the prescribed depth in the film thickness direction (surface portion) 4c in the exposed portion. The etching can be either dry etching or wet etching, but if it is a large-sized photomask, wet etching is preferable. The etchant is an etching liquid or an etching gas. In either case, since an etchant having etching selectivity to the intermediate film 4 (an etchant that does not etch the light shielding film 5) is used, only the intermediate film 4 is selectively etched.

[0081] The material of the intermediate film 4 and / or the etchant of the intermediate film 4 are selected so that the etching rate of the intermediate film 4 is low. Thereby, only the surface portion 4c of the intermediate film 4 can be etched. Further, by selecting an appropriate etching rate, the etching amount (film loss amount of the intermediate film 4) can be appropriately controlled.

[0082] As shown in Figure 3 (a), Figure 3 (c), Figure 4 (a) and Figure 4 (c), the intermediate film surface etching process (process 5) is performed a plurality of times (processes 5-1, 5-2, 5-3, 5-4). The number of times of the intermediate film surface etching process (process 5) is (the number of gradation portions 31 + 1) times. In the present embodiment, since the gradation portion 31 is three-tone, the number of times of the intermediate film surface etching process (process 5) is four times.

[0083] In the light shielding film side etching process (process 6), as shown in Figure 3 (b), the prescribed depth (prescribed width) of the portion 5d in the inside direction from the end surface of the exposed edge 5a in the light shielding film 5 is side-etched and removed. The side-etching is performed by the same method and the same etchant as in the light shielding film etching process (process 4).

[0084] As shown in Figure 3 (b), Figure 3 (d) and Figure 4(b) shown, a plurality of light-shielding film side etching processes (process 6) are performed (process 6-1, 6-2, 6-3). The number of times of the light-shielding film side etching process (process 6) is the same as the number of color tones of the gradation portion 31. In other words, the number of times of the light-shielding film side etching process (process 6) is (the number of times of the intermediate film surface etching process (process 5) - 1). In the present embodiment, since the gradation portion 31 is three color tones, the number of times of the intermediate film surface etching process (process 5) is four, and thus the number of times of the light-shielding film side etching process (process 6) is three. In addition, in the present embodiment, the number of times of the intermediate film surface etching process (process 5) is four, and thus the number of times of the light-shielding film side etching process (process 6) is three. However, the number of times of the intermediate film surface etching process (process 5) and the number of times of the light-shielding film side etching process (process 6) are not limited to these numbers. The number of times of the intermediate film surface etching process (process 5) and the number of times of the light-shielding film side etching process (process 6) can be appropriately set according to the thickness of the intermediate film 4 and the thickness of the light-shielding film 5. Figure 3 (b), Figure 3 (d), and Figure 4 In (b), the etching amount of the side etching is shortened from the relationship of the width dimension of the paper. The actual image is close to the image described in Figure 9 (b).

[0085] The intermediate film surface etching process (process 5) and the light-shielding film side etching process (process 6) are alternately repeated a plurality of times, starting and ending with the intermediate film surface etching process (process 5). In the present embodiment, they are performed in the order of process 5-1, process 6-1, process 5-2, process 6-2, process 5-3, process 6-3, and process 5-4. By alternately repeating the surface etching of the intermediate film 4 and the side etching of the light-shielding film 5 a plurality of times, the exposed portion of the intermediate film 4 has a shape in which the closer to the transparent substrate 2, the more it expands outward. In more detail, the exposed portion of the intermediate film 4 has a stepped shape.

[0086] Each of the processes 5-1, 5-2, 5-3, and 5-4 of the intermediate film surface etching process (process 5) is performed in a divided etching amount such that the total of the etching amounts of the processes is the film thickness of the intermediate film 4. Preferably, each process is performed in an etching amount that is the film thickness of the intermediate film 4 divided by the number of times of the intermediate film surface etching process (process 5). For example, when the film thickness of the intermediate film 4 is 100 nm and the number of times of the intermediate film surface etching process (process 5) is four, the etching amount of each process is 25 nm. However, it is not necessary that the etching amount of each process be the same. The etching amount of each process can be different. In any case, as described above, since the etching rate of the intermediate film 4 is low, such fine surface etching can be performed. However, in the case where the total etching amount is equal to the film thickness, the intermediate film 4 can remain unetched on the surface of the semi-permeable film 3. Therefore, over-etching is performed in the last intermediate film surface etching process (process 5-4). This is Figure 4 (b) described in (c) is Figure 3 (a), Figure 3 (c), Figure 4 The reason why the etching amount described in (a) is

[0087] Each of the processes 6-1, 6-2, 6-3 of the light-shielding film side etching process (process 6) is performed in a manner corresponding to the transmittance gradient of the gradual change portion 31 and toward the designed position of the edge 5a of the light-shielding film 5 in a divided etching amount.

[0088] In the semi-permeable film etching process (process 7), as shown in Figure 4 (d), the intermediate film 4 is used as a mask for etching treatment, and the exposed portion 3d of the semi-permeable film 3 is etched and removed. The etching is performed by the same method and the same etchant as in the light-shielding film etching process (process 4) or the light-shielding film side etching process (process 6). In addition, since the etchant used has etching selectivity with respect to the light-shielding film 5 and the semi-permeable film 3, not only the exposed portion 3d of the semi-permeable film 3 is etched, but also a portion 5d of the light-shielding film 5 having the same depth from the end surface of the exposed edge 5a to the inside direction is also etched.

[0089] In addition, in the semi-permeable film etching process (process 7), in order not to leave the unetched semi-permeable film 3 on the surface of the transparent substrate 2, over-etching is performed in which the etching amount is additionally increased by an amount corresponding to the film thickness of the semi-permeable film 3.

[0090] In the resist film removal process (process 8), as shown in Figure 5 (a), the resist film 6 is removed. The resist film 6 is removed by a method of ashing or immersion in a resist peeling solution.

[0091] Through the above processes 1 to 8, an intermediate of the multi-tone photomask 1 is completed. As shown in Figure 5 (a), the intermediate is composed of these laminated film structures, that is, includes the semi-permeable film 3 of a prescribed pattern shape laminated on the transparent substrate 2, the intermediate film 4 laminated in a manner of overlapping the semi-permeable film 3, and the light-shielding film 5 of a prescribed pattern shape laminated on the intermediate film 4 in a manner of exposing at least a portion of the peripheral region of the intermediate film 4, and at least a portion of the exposed portion of the intermediate film 4 has a shape that expands more outward (in a direction away from the light-shielding film 5 among the surface directions) as it approaches the edge 4a of the transparent substrate 2. More specifically, at least a portion of the exposed portion of the intermediate film 4 has a stepped shape that expands more outward as it approaches the edge 4a of the transparent substrate 2. The number of steps is the same as the number of tones of the gradual change portion 31. In the present embodiment, since the gradual change portion 31 is three tones, the number of steps is three (lower step portion 4d, middle step portion 4e, upper step portion 4f). The subsequent processes 9 and 10 are processes on the prepared intermediate.

[0092] In the intermediate film divided etching process (process 9), as shown in Figure 5(b) shown, surface etching is performed on a prescribed depth in the film thickness direction (surface portion) 4c of the exposed portion of the intermediate film 4 using the light shielding film 5 as a mask for etching treatment. The surface etching is performed by the same method and the same etchant as in the intermediate film surface etching step (step 5). Since an etchant having etching selectivity with respect to the intermediate film 4 (an etchant that does not etch the semi-permeable film 3 and the light shielding film 5) is used, only the intermediate film 4 is selectively etched.

[0093] Further, in the intermediate film partial etching step (step 9), as in the intermediate film surface etching step (step 5), the etching rate of the intermediate film 4 is low. Thus, only the surface portion 4c of the intermediate film 4 can be etched. Further, by selecting an appropriate etching rate, the etching amount (film loss amount of the intermediate film 4) can be appropriately controlled.

[0094] As Figure 5 (b), Figure 5 (d) and Figure 6 (b) shown, the intermediate film partial etching step (step 9) is performed a plurality of times (steps 9-1, 9-2, 9-3). The number of times of the intermediate film partial etching step (step 9) is the same as the number of stages of the intermediate film 4 (i.e., the number of gradations of the gradual change portion 31). In the present embodiment, since the number of stages of the intermediate film 4 is three, the number of times of the intermediate film partial etching step (step 9) is three.

[0095] In the plasma treatment step (step 10), as Figure 5 (c) shown, plasma is irradiated to the surface of the exposed portion of the semi-permeable film 3 by a plasma treatment device. The plasma treatment device can be any one of a device that generates plasma and performs surface treatment under atmospheric pressure (atmospheric pressure plasma treatment device) and a device that generates plasma and performs surface treatment under reduced pressure in a closed chamber (reduced pressure plasma treatment device), but if the photomask is of a large size, the atmospheric pressure plasma treatment device is preferable.

[0096] The transmittance of the semi-permeable film 3 irradiated with the plasma changes (increases) depending on the irradiation time. On the other hand, since the portion of the semi-permeable film 3 covered with the intermediate film 4 is not affected by the plasma treatment, the transmittance does not change. Thus, the intermediate film 4 functions as a mask for plasma treatment.

[0097] As Figure 5 (c) and Figure 6(a) shown, a plurality of plasma treatment processes (process 10) (processes 10-1, 10-2) are performed. The number of plasma treatment processes (process 10) is (the number of gradation portions 31 - 1). In other words, the number of plasma treatment processes (process 10) is (the number of intermediate film partial etching processes (process 9) - 1). In the present embodiment, since the gradation portion 31 is three-tone, the number of intermediate film partial etching processes (process 9) is three, and thus the number of plasma treatment processes (process 10) is two.

[0098] The intermediate film partial etching processes (process 9) and the plasma treatment processes (process 10) are alternately repeated a plurality of times, starting and ending with the intermediate film partial etching processes (process 9). In the present embodiment, they are performed in the order of process 9-1, process 10-1, process 9-2, process 10-2, process 9-3.

[0099] The first intermediate film partial etching process (process 9-1) is performed with an etching amount corresponding to the film thickness of the lower section portion 4d of the intermediate film 4. Thereby, in the first intermediate film partial etching process (process 9-1), the lower section portion 4d of the intermediate film 4 is removed. Therefore, in the first plasma treatment process (process 10-1), plasma is irradiated to the surface of the exposed portion of the semi-permeable membrane 3 by removing the lower section portion 4d of the intermediate film 4, and the transmittance of the portion is made higher.

[0100] The second intermediate film partial etching process (process 9-2) is performed with an etching amount corresponding to the film thickness of the middle section portion 4e of the intermediate film 4 whose height is lowered by the first intermediate film partial etching process (process 9-1). Thereby, in the second intermediate film partial etching process (process 9-2), the middle section portion 4e of the intermediate film 4 is removed. Therefore, in the second plasma treatment process (process 10-2), plasma is further irradiated to the surface of the exposed portion of the semi-permeable membrane 3 by removing the lower section portion 4d of the intermediate film 4, so that the transmittance of the portion is further made higher, and plasma is irradiated to the surface of the exposed portion of the semi-permeable membrane 3 by removing the middle section portion 4e of the intermediate film 4, so that the transmittance of the portion is made higher. Thereby, in the gradation portion 31, the outermost portion 31A having the highest transmittance and the intermediate portion 31B having a transmittance next to the outermost portion 31A are formed.

[0101] The third intermediate film partial etching process (process 9-3) is performed by an etching amount corresponding to the film thickness of the upper section 4f of the intermediate film 4 whose height has been reduced by the second intermediate film partial etching process (process 9-2). Thus, in the third intermediate film partial etching process (process 9-3), the upper section 4f of the intermediate film 4 is removed. The innermost portion 31C of the gradual change portion 31 is a portion exposed by the removal of the upper section 4f of the intermediate film 4. The innermost portion 31C is not subjected to the plasma treatment. Thus, the transmittance of the innermost portion 31C is the same as the transmittance of the semi-permeable film 3, and is the lowest transmittance in the gradual change portion 31.

[0102] As described above, the transmittances of the respective portions 31A, 31B, 31C of the gradual change portion 31 have a correlation with the cumulative value of the irradiation time of the plasma. As Figure 7 As shown in (a), if the irradiation time S2 is required to make the transmittance of the outermost portion 31A T3, and the irradiation time S1 is required to make the transmittance of the intermediate portion 31B T2, in the first plasma treatment process (process 10-1), the plasma is irradiated for the time (S2-S1), and in the second plasma treatment process (process 10-2), the plasma is irradiated for the time S1. In this way, the irradiation time in each of the processes 10-1, 10-2 of the plasma treatment process (process 10) can be determined in accordance with the transmittances of the respective portions 31A, 31B, 31C of the gradual change portion 31.

[0103] Then, by appropriately setting the irradiation time in each of the processes 10-1, 10-2 of the plasma treatment process (process 10), the transmittance gradient of the gradual change portion 31 can be appropriately set. For example, Figure 7 The example shown in (a) is an example in which the transmittance gradient of the gradual change portion 31 becomes linear by making the irradiation time in each of the processes 10-1, 10-2 equal. Further, Figure 7 The example shown in (b) is an example in which the transmittance gradient of the gradual change portion 31 becomes a curve by making the irradiation time in the process 10-2 longer than the irradiation time in the process 10-1. Further, Figure 7 The example shown in (c) is an example in which the transmittance gradient of the gradual change portion 31 becomes a curve by making the irradiation time in the process 10-2 shorter than the irradiation time in the process 10-1.

[0104] Further, in each of the processes 9-1, 9-2, 9-3 of the intermediate film partial etching process (process 9), over-etching is performed so that the intermediate film 4 which has not been completely etched is not left on the surface of the semi-permeable film 3. Figure 5 (b) the etching amount is larger than the film thickness of the lower section 4d of the intermediate film 4, Figure 5 (d) the etching amount is larger than the film thickness of the middle section 4e of the intermediate film 4 whose film thickness has been reduced, Figure 6(b) The film thickness of the upper section 4f of the intermediate film 4, which is described as being reduced by the etching amount, is just for this reason.

[0105] Through the above procedures 1 to 9-3, the multitone photomask 1 is completed as shown in Figure 6 (c) (and Figure 1 ) The manufacturing method of the multitone photomask 1 according to the present embodiment requires only one time of the drawing procedure. Therefore, there is no need for alignment in the manufacturing process of the multitone photomask. Therefore, the manufacturing method of the multitone photomask 1 and the multitone photomask 1 according to the present embodiment have no alignment deviation, whereby the lead time can be shortened and a high-precision multitone photomask can be manufactured.

[0106] In addition, the conditions of the manufacturing method of the multitone photomask 1 are shown below as guide values.

[0107] • Process temperature of each etching procedure (procedures 4 to 7, procedure 9): 20 to 24°C (for example, 23°C)

[0108] • Process time of the light-blocking film etching procedure (procedure 4): 60 to 200 seconds

[0109] • Process time of each procedure of the intermediate film 4 etching procedure (procedure 5, procedure 9): 5 to 10 minutes

[0110] • Process time of each procedure of the light-blocking film side etching procedure (procedure 6): 500 to 2000 seconds

[0111] • Process time of the semi-permeable film etching procedure (procedure 7): 20 to 100 seconds

[0112] • In addition, as an example, the etching rate of each of the semi-permeable film 3 and the light-blocking film 5 is about 1 nm / sec; as an example, the etching rate of the intermediate film 4 is about 4 nm / min.

[0113] Next, the consideration method of the design of the resist pattern (the position on the design of the edge 6a of the resist film 6) involved in the explanation part of the drawing procedure (procedure 2) will be described.

[0114] The position of the edge 3a of the semi-permeable film 3 is formed as the position on the design in the semi-permeable film etching procedure (procedure 7). Therefore, in Figure 8 the relationship between the position on the design of the edge 6a of the resist film 6 and the position on the design of the edge 3a of the semi-permeable film 3 is shown. From Figure 8 it is known that the difference A of both is represented by the following equation. In addition, it is assumed that in each of the above etching procedures, the semi-permeable film 3, the intermediate film 4, and the light-blocking film 5 are etched at the same speed (etching rate) in the film thickness direction and the inner direction (hereinafter the same).

[0115] Difference A = film thickness FT3 of semi-permeable film 3 + over-etching amount OE3 in process 7 + film thickness FT4 of intermediate film 4 + over-etching amount OE4 in process 5 + film thickness FT5 of light-shielding film 5 + over-etching amount OE5 in process 4

[0116] Therefore, the designed position of the edge 6a of the resist film 6, that is, the drawing data of the resist pattern, is data that is shifted only by the difference A outward from the designed position of the edge 3a of the semi-permeable film 3.

[0117] In addition, the position of the edge 5a of the light-shielding film 5 is also formed as a designed position in the semi-permeable film etching process (process 7). Therefore, in Figure 9 The relationship between the designed position of the edge 6a of the resist film 6 and the designed position of the edge 5a of the light-shielding film 5 is shown in FIG. 8. Figure 9 As is apparent from FIG. 8, the difference B between the two is represented by the following formula.

[0118] Difference B = film thickness FT3 of semi-permeable film 3 + over-etching amount OE3 in process 7 + total side etching amount (SE5-1 to 3) in process 6 + film thickness FT5 of light-shielding film 5 + over-etching amount OE5 in process 4

[0119] Therefore, based on this formula, by appropriately setting the side etching amount in each of the processes 6-1, 6-2, 6-3 of the light-shielding film side etching process (process 6), it is possible to form the position of the edge 5a of the light-shielding film 5 as a designed position.

[0120] Next, the transmittance gradient of the gradual change portion 31 will be described.

[0121] Figure 10 The upper drawing of FIG. 9 shows the change in the layered film structure of the photomask blank caused by the intermediate film surface etching process (process 5) and the light-shielding film side etching process (process 6), Figure 10The lower drawing of FIG. 6 shows the multitone photomask 1, and both drawings are recorded in a state where the position in the plane direction is aligned in the up-down direction. As is apparent therefrom, the positions of the stepped edge 5a of the light shielding film 5 and the edge 4a of the intermediate film 4 and the boundaries of the sections 4d, 4e, 4f caused by the light shielding film side etching process (process 6) are slightly shifted due to the side etching of the sections 4d, 4e, 4f of the intermediate film 4, but have a correlation. Further, as is apparent therefrom, the positions of the edge 4a of the intermediate film 4 and the boundaries of the sections 4d, 4e, 4f and the edge 3a of the gradual change portion 31 and the boundaries 3b, 3c of the gradual change portion 31 are slightly shifted due to the side etching of the sections 4d, 4e, 4f of the intermediate film 4, but have a correlation. Further, as is apparent therefrom, the positions of the stepped edge 5a of the light shielding film 5 and the edge 3a of the gradual change portion 31 and the boundaries 3b, 3c of the gradual change portion 31 caused by the light shielding film side etching process (process 6) are slightly shifted due to the side etching of the sections 4d, 4e, 4f of the intermediate film 4, but have a correlation.

[0122] Therefore, by appropriately setting the side etching amount in each of the processes 6-1, 6-2, 6-3 of the light shielding film side etching process (process 6), the transmittance gradient of the gradual change portion 31 can be appropriately set. For example, Figure 10 The example shown in the lower drawing of FIG. 6 (and Figure 1 ) is an example in which the transmittance gradient of the gradual change portion 31 becomes linear by making the side etching amounts equal. Further, Figure 11 The example shown in (a) of FIG. 7 is an example in which the width of the region gradually widens toward the edge 3a of the half transparent film 3, and the transmittance gradient of the gradual change portion 31 becomes a curve. Further, Figure 11 The example shown in (b) of FIG. 7 is an example in which the width of the region gradually narrows toward the edge 3a of the half transparent film 3, and the transmittance gradient of the gradual change portion 31 becomes a curve.

[0123] Next, the film thickness of the intermediate film 4 involved in the explanation of the photomask blank will be explained.

[0124] As is apparent from Figure 12 , the overhang amount of the protruding end portion 5b of the light shielding film 5 is represented by the following equation.

[0125] Overhang amount = Film thickness FT4 of intermediate film 4 - {Film thickness FT4 / (Number of tones of gradual change portion 31 + 1) + Over-etching amount OE4 in process 5} + Over-etching amount OE4 in process 9-3

[0126] According to this equation, the film thickness FT4 of the intermediate film 4 is represented by the following equation.

[0127] Film thickness FT4 = (Overhang amount + Over-etching amount OE4 in process 5 - Over-etching amount OE4 in process 9-3) / {1 - 1 / (Number of tones of gradual change portion 31 + 1)}

[0128] Here, in order to prevent deformation caused by sagging of the protruding end portion 5b, the overhang amount is preferably 150 nm or less. In this case, with each over-etching amount OE4 being 15 nm and the gradual change portion 31 being three color tones, the film thickness of the intermediate film 4 is 200 nm or less.

[0129] Next, regarding the lower limit of the film thickness of the intermediate film 4, in order to form an appropriate gradual change portion 31, it is important to control the film thickness of the intermediate film 4 in the intermediate film surface etching process (process 5) and the intermediate film batch etching process (process 9). If the etching rate is too high, it is difficult to control the film thickness of the intermediate film 4. On the contrary, if the etching rate is too low, it is necessary to spend processing time, and the productivity is reduced. Therefore, preferably, the etching rate is about 4 nm / min, and the process time of each of the intermediate film surface etching process (process 5) and the intermediate film batch etching process (process 9) is preferably about 7.5 minutes.

[0130] Thus, the film thickness FT4 of the intermediate film 4 is represented by the following equation.

[0131] Film thickness FT4 = (number of color tones of the gradual change portion 31 + 1) x 30 nm

[0132] As described above, by setting the film thickness of the intermediate film 4 in the range of 90 nm to 200 nm, it is possible to manufacture a gradual change portion 31 of two to five color tones (i.e., a high-precision multi-tone photomask of four to seven color tones).

[0133] Next, the entire pattern of the multi-tone photomask 1 will be described.

[0134] As one example, the unit pattern 1A of the multi-tone photomask 1 is in a form in which the semi-transmissive portion 30 (the gradual change portion 31) is provided in the entire peripheral region of the light shielding portion 50. Figure 13 Fig. (a) is an island-shaped (convex-shaped) multi-tone photomask 1 in which a plurality of unit patterns 1A,... are two-dimensionally arranged at a constant pitch with a large gap therebetween (so that the region of the transmissive portion 20 is sufficiently wide). Figure 13 Fig. (b) is a hole-shaped (concave-shaped) multi-tone photomask 1 in which a plurality of unit patterns 1A,... in which the region of the light shielding portion 50 is sufficiently widened are arranged at a constant pitch with each other being close (so that the region of the transmissive portion 20 is sufficiently narrow).

[0135] Furthermore, the present application is not limited to the above-described embodiments, and various changes can be made within the scope of the gist of the present application.

[0136] In the above embodiment, the multi-tone photomask is a five-tone. However, the present application is not limited to this. By making the number of steps of the step of the intermediate film four or more (the number of steps of the middle section two or more), the middle section of the gradual change section is formed two or more, and a multi-tone photomask of six or more tones can be manufactured. Alternatively, by making the number of steps of the step of the intermediate film two (not providing the middle section), the middle section of the gradual change section is not formed, and a multi-tone photomask of four tones can be manufactured.

[0137] Further, in the above embodiment, the gradual change section 31 is provided in the entire region of the semi-transmissive section 30, and coincides with the semi-transmissive section 30. However, the present application is not limited to this. The gradual change section can also be provided in a part of the semi-transmissive section.

[0138] Further, in the above embodiment, the intermediate film surface etching step (step 5) and the light shielding film side etching step (step 6) are alternately repeated a plurality of times starting with the intermediate film surface etching step (step 5). However, the present application is not limited to this. For example, as shown in Figure 14 and Figure 15 , the intermediate film surface etching step (step 5) and the light shielding film side etching step (step 6) can also be alternately repeated a plurality of times starting with the light shielding film side etching step (step 6). In addition, in the examples of Figure 14 and Figure 15 , the number of times of the intermediate film surface etching step (step 5) is the same as the number of tones of the gradual change section 31. The number of times of the light shielding film side etching step (step 6) is (the number of tones of the gradual change section 31 + 1). In other words, the number of times of the light shielding film side etching step (step 6) is (the number of times of the intermediate film surface etching step (step 5) + 1).

[0139] Further, in the above embodiment and the examples of Figure 14 and Figure 15 , either one of the intermediate film surface etching step (step 5) and the light shielding film side etching step (step 6) is one more step. However, the present application is not limited to this. For example, as shown in Figure 16 and Figure 17 , either one of the intermediate film surface etching step (step 5) and the light shielding film side etching step (step 6) can be the same number of steps regardless of which step is started.

[0140] Further, in the above embodiment, the plasma treatment step (step 10) is performed after the first intermediate film sub-etching step (step 9-1) and the second intermediate film sub-etching step (step 9-2). However, the present application is not limited to this. The plasma treatment step (step 10) can also be performed after the last intermediate film sub-etching step.

[0141] In addition, in the present application, a phase shift film can be used instead of the light shielding film. As long as the phase shift film is laminated with the lower semi-permeable film, the optical density (OD value) is 2.7 or more.

Claims

1. A method for manufacturing a multi-tone photomask, the multi-tone photomask comprising a transmissive portion, a semi-transmissive portion, and a light-shielding portion, wherein the semi-transmissive portion includes a gradient portion composed of multiple regions whose transmittance increases in a stepped manner towards the boundary between the semi-transmissive portion and the transmissive portion; characterized in that, The method for manufacturing this multi-tone photomask includes: The intermediate preparation process prepares an intermediate consisting of the following laminated film structures: a semi-permeable film having a defined pattern shape and laminated on a transparent substrate; an intermediate film having different etching characteristics than the semi-permeable film and laminated on top of the semi-permeable film; and a light-shielding film having a defined pattern shape and the same etching characteristics as the semi-permeable film and laminated on the intermediate film such that at least a portion of the peripheral area of ​​the intermediate film is exposed; at least a portion of the exposed portion of the intermediate film has a shape in which the edges extend outward the closer it is to the transparent substrate. The intermediate film is etched in multiple stages, and the exposed part of the intermediate film is etched in multiple stages and finally removed. The plasma treatment process involves applying plasma to the exposed portion of the semi-permeable membrane after each etching cycle, except for the final one, or including the final one, to alter the transmittance of that portion.

2. The method for manufacturing a multi-tone photomask according to claim 1, characterized in that, The intermediate preparation process includes the intermediate manufacturing process for manufacturing intermediates. The intermediate manufacturing process includes: The resist film formation process forms a resist film on the surface of the photomask blank; The resist pattern forming process forms the specified resist pattern; In the process of etching the light-shielding film, the resist pattern is used as a mask to etch and remove the exposed part of the light-shielding film; The shaping process involves alternating and repeating the etching of the intermediate film surface and the etching of the light-shielding film side multiple times to shape the exposed portion of the intermediate film into a shape where the edges extend outwards as it gets closer to the transparent substrate. Specifically, the etching of the intermediate film surface uses the light-shielding film as a mask to etch and remove a portion of the exposed portion of the intermediate film at a predetermined depth in the film thickness direction. The etching of the light-shielding film side involves etching and removing a portion of the light-shielding film at a predetermined depth in the inward direction, starting from the end face of the exposed edge. The semi-permeable membrane etching process uses the intermediate membrane as a mask to etch and remove the exposed portion of the semi-permeable membrane; The resist film removal process removes the resist film.

3. The method for manufacturing a multi-tone photomask according to claim 2, characterized in that, In the shaping process, this part of the intermediate membrane is shaped into a stepped shape.

4. The method for manufacturing a multi-tone photomask according to claim 2 or 3, characterized in that, The number of etching operations on the intermediate film surface and the light-shielding film side is set according to the number of hues in the gradient section.

5. The method for manufacturing a multi-tone photomask according to claim 2 or 3, characterized in that, The etching amount of each intermediate film surface etching is set such that the total etching amount of each intermediate film surface etching is the same as or greater than the thickness of the intermediate film.

6. The method for manufacturing a multi-tone photomask according to claim 2 or 3, characterized in that, The etching amount of each etching step on the light-shielding film side is set according to the transmittance gradient of the gradient section.

7. The method for manufacturing a multi-tone photomask according to claim 2 or 3, characterized in that, The position of the edge of the resist pattern corresponding to the gradient is the position offset outward relative to the edge of the semi-permeable membrane after the semi-permeable membrane etching process, by the total thickness of the semi-permeable membrane, intermediate membrane, and light-shielding membrane, or a value greater than that total value.

8. A method for manufacturing a multi-tone photomask according to any one of claims 1 to 3, characterized in that, As an intermediate film, a film with a lower etching rate than the semi-permeable film and the light-shielding film is selected.

9. A method for manufacturing a multi-tone photomask according to any one of claims 1 to 3, characterized in that, The number of etching steps and plasma treatments of the intermediate film is set according to the number of hues in the gradient section.

10. A method for manufacturing a multi-tone photomask according to any one of claims 1 to 3, characterized in that, The processing time for each plasma treatment is set according to the transmittance gradient of the gradient section.

11. A multi-tone light mask comprising a transmissive portion, a semi-transmissive portion, and a light-shielding portion, characterized in that, include: A semi-permeable membrane having a prescribed pattern shape is laminated on a transparent substrate; An intermediate membrane, having different etching characteristics from the semipermeable membrane, is laminated on the semipermeable membrane in such a way that at least a portion of the peripheral region of the semipermeable membrane is exposed; The light-shielding film, having a prescribed pattern shape and the same etching characteristics as the semi-permeable film, is laminated on top of the intermediate film. At least a portion of the exposed part of the semipermeable membrane has a gradient section consisting of multiple regions on the same membrane in which the transmittance increases stepwise toward the edge of the semipermeable membrane.

12. A multi-tone light mask comprising a transmissive portion, a semi-transmissive portion, and a light-shielding portion, characterized in that, include: A semi-permeable membrane having a prescribed pattern shape is laminated on a transparent substrate; An intermediate membrane, having different etching characteristics from the semipermeable membrane, is laminated on the semipermeable membrane in such a way that at least a portion of the peripheral region of the semipermeable membrane is exposed; The light-shielding film, having a prescribed pattern shape and the same etching characteristics as the semi-permeable film, is laminated on top of the intermediate film. At least a portion of the exposed part of the semipermeable membrane has a gradient section consisting of multiple regions whose transmittance increases stepwise toward the edge of the semipermeable membrane. By positioning the edge of the interlayer film further inward than the edge of the light-shielding film, a cut bottom without the interlayer film is formed below the edge of the light-shielding film, thereby causing the end of the light-shielding film to overhang and become a protruding end.

13. A multi-tone light mask comprising a transmissive portion, a semi-transmissive portion, and a light-shielding portion, characterized in that, include: A semi-permeable membrane having a prescribed pattern shape is laminated on a transparent substrate; An intermediate membrane, having different etching characteristics from the semipermeable membrane, is laminated on the semipermeable membrane in such a way that at least a portion of the peripheral region of the semipermeable membrane is exposed; The light-shielding film, having a prescribed pattern shape and the same etching characteristics as the semi-permeable film, is laminated on top of the intermediate film. At least a portion of the exposed part of the semipermeable membrane has a gradient section consisting of multiple regions whose transmittance increases stepwise toward the edge of the semipermeable membrane. The thickness of the intermediate film is above 90nm and below 200nm.

Images