Photomask manufacturing method and phase shift mask

Abstract

To provide a photomask manufacturing method that can achieve even higher resolution of photomasks than conventional photomask manufacturing methods.SOLUTION: The edge position of a second area of a photomask pattern (the edge position of a semi-transparent film 3) is defined based not on the edge position of a second pattern 4B of an upper layer film pattern on the side opposite a first pattern 4A, but on the edge position of the second pattern 4B of the upper layer film pattern on the first pattern 4A side. Accordingly, the width of the second pattern 4B of the upper layer pattern is not a factor in setting the width of the second area (the width of an exposed portion of the semi-transparent film 3). Therefore, the present invention can achieve even higher resolution of photomasks than conventional photomask manufacturing methods.SELECTED DRAWING: Figure 4

Description

[Technical field]

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

[0002] Phase shift masks and halftone masks are known as photolithography techniques. A phase shift mask is a photomask that has a phase shift film on part of a transparent substrate and has the function of improving resolution and depth of focus (DOF) by changing the phase and intensity of light passing through this part. A halftone mask is a photomask that has a halftone film on part of a transparent substrate and has the function of realizing multiple gradations of three or more levels by changing the intensity of light passing through this part.

[0003] In the conventional photomask manufacturing method, at least two drawing steps are required: a drawing step (exposure step) of a pattern constituting a light-shielding portion and a drawing step of a pattern constituting a semi-transmitting portion. When the drawing steps are performed multiple times, positional deviation of the patterns formed in each step is likely to occur.

[0004] One solution to this problem is to use alignment marks. When performing the second or subsequent drawing process, the alignment mark created in the first drawing process is read, and alignment (positioning) is performed using this alignment mark as a reference. However, even when using alignment marks, it is impossible to completely eliminate pattern position shifts (alignment deviations), and alignment deviations of up to 0.5 μm can occur. For this reason, the impact of this problem is becoming greater as photomasks become more fine.

[0005] Therefore, a method for manufacturing a photomask that can perform the drawing process in one step has been considered. For example, the method for manufacturing a photomask described in Patent Document 1 is as follows: A method for manufacturing a photomask comprising: an underlayer film formed on a transparent substrate; and an upper layer film formed on the underlayer film so that at least a part of a peripheral region of the underlayer film is exposed; the photomask having a pattern constituted by a first region of a laminated portion of the underlayer film and the upper layer film and a second region of the underlayer film, i) a photomask blanks preparation step of preparing a photomask blank in which a lower layer film and an upper layer film are laminated on a transparent substrate; ii) a first resist pattern forming step of forming a first resist pattern including a first pattern corresponding to the first region and a second pattern spaced apart from the first pattern and having an edge on the opposite side to the first pattern set at a position corresponding to the position of the edge of the second region; iii) a first upper layer film etching process, in which an exposed portion of the upper layer film is removed by etching using the first resist pattern as a mask, to form an upper layer film pattern including a first pattern corresponding to the first region and a second pattern (temporary pattern) spaced apart from the first pattern and having an edge on the opposite side to the first pattern set at a position corresponding to the position of the edge of the second region; iv) a second resist pattern formation process for forming a second resist pattern that covers the first pattern of the upper layer film pattern, the exposed portion of the lower layer film between the first pattern and the second pattern (temporary pattern) of the upper layer film pattern, and a portion of the second pattern (temporary pattern) of the upper layer film pattern excluding a portion including an edge on the opposite side to the first pattern; v) an underlayer film etching step of removing exposed portions of the underlayer film by etching using the second resist pattern and the second pattern (temporary pattern) of the overlayer film pattern as a mask; vi) A second upper layer film etching process for removing the second pattern (temporary pattern) of the upper layer film pattern by etching.

[0006] According to the photomask manufacturing method described in Patent Document 1, except for the drawing process in which the positional accuracy of the pattern is not important (secondary resist pattern forming process), the drawing process can determine the final required pattern dimensions in one step (first resist pattern forming process). This eliminates the need for excessive alignment accuracy in the photomask manufacturing process. Since so-called self-aligned pattern formation is performed, the photomask manufacturing method described in Patent Document 1 can achieve high-definition photomasks without misalignment. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2014-2255 A Summary of the Invention [Problem to be solved by the invention]

[0008] However, in the photomask manufacturing method described in Patent Document 1, the second pattern (temporary pattern) of the upper layer film pattern needs to be formed to have a width greater than an alignment misalignment of up to 0.5 μm so that the second resist pattern reliably covers the relevant portion of the second pattern (temporary pattern) of the upper layer film pattern and so that the exposed portion of the lower layer film between the first pattern and the second pattern (temporary pattern) of the upper layer film pattern is not exposed from the second resist pattern.

[0009] For this reason, when manufacturing a photomask in which the first region is a light-shielding portion, the second region is a phase shift portion, and the second region functions as a rim portion of the light-shielding portion, and in which a line-and-space pattern in which lines (light-shielding portion) with a width in μm units and spaces (transmitting portion) with a width in μm units are arranged in parallel, or in which a hole pattern in which holes (transmitting portion) with a size in μm units are arranged, the width of the second region (rim portion) becomes large by the amount including the width of the second pattern (provisional pattern) of the upper layer film pattern, and cannot be formed smaller than the sum of the width of the second pattern (provisional pattern) and the beam diameter of the drawing device. This results in restrictions on the size of the second region (rim portion).

[0010] Therefore, the present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a photomask manufacturing method that can achieve even higher resolution photomasks compared to conventional photomask manufacturing methods. [Means for solving the problem]

[0011] The method for producing a photomask according to the present invention includes the steps of: A method for manufacturing a photomask comprising: an underlayer film formed on a transparent substrate; and an upper layer film formed on the underlayer film so that at least a part of a peripheral region of the underlayer film is exposed; the photomask having a pattern constituted by a first region of a laminated portion of the underlayer film and the upper layer film and a second region of the underlayer film, a photomask blanks preparation step of preparing a photomask blank in which a lower layer film and an upper layer film are laminated on a transparent substrate; a first resist pattern forming step of forming a first resist pattern including a first pattern corresponding to the first region and a second pattern spaced apart from the first pattern and having an edge on the first pattern side set at a position corresponding to the position of an edge of the second region; a first upper layer film etching process in which an upper layer film pattern is formed including a first pattern corresponding to a first region and a second pattern spaced apart from the first pattern and having an edge on the first pattern side set at a position corresponding to the position of an edge of the second region by removing an exposed portion of the upper layer film by etching using the first resist pattern as a mask; a second resist pattern forming process for forming a second resist pattern that covers the first pattern of the upper layer film pattern, the exposed portion of the lower layer film between the first pattern and the second pattern of the upper layer film pattern, and at least a portion including an edge on the first pattern side of the second pattern of the upper layer film pattern, and exposes at least a part of the other portion of the second pattern of the upper layer film pattern; a second upper layer film etching process for removing the second pattern of the upper layer film pattern by etching; and an underlayer film etching process for removing exposed portions of the underlayer film by etching using the second resist pattern as a mask. A method for manufacturing a photomask.

[0012] Here, as one aspect of the method for producing a photomask according to the present invention, The lower and upper layers are formed of a film in which the first region functions as a light shielding portion and the second region functions as a phase shift portion. The above configuration can be adopted.

[0013] Also, in this case, A phase shift film is used as the underlayer film. A light-shielding film is used as the upper layer. The above configuration can be adopted.

[0014] In another aspect of the method for producing a photomask according to the present invention, The second region functions as a rim portion of the light blocking portion. The above configuration can be adopted.

[0015] In another aspect of the method for producing a photomask according to the present invention, The photomask pattern is either a line and space pattern, a hole pattern or a dot pattern. The above configuration can be adopted. Effect of the Invention

[0016] According to the present invention, the position of the edge of the second region of the photomask pattern is determined based on the position of the edge of the second pattern of the upper layer film pattern on the side of the first pattern, not the position of the edge of the second pattern of the upper layer film pattern on the side opposite to the first pattern. As a result, the width of the second pattern of the upper layer film pattern is not a factor in setting the width of the second region. Therefore, according to the present invention, it is possible to realize a photomask with even higher resolution than the conventional photomask manufacturing method. [Brief description of the drawings]

[0017] [Figure 1] Fig. 1(a) is an enlarged plan view of a main part of a photomask according to embodiment 1. Fig. 1(b) is a cross-sectional view taken along line AA in Fig. 1(a). [Diagram 2] 2(a) to (d) are explanatory diagrams of the method for producing a photomask according to the first embodiment. [Diagram 3] 3(a) to (d) are explanatory diagrams continuing from FIG. [Figure 4] 4(a) to (d) are explanatory diagrams continuing from FIG. [Diagram 5] 5(a) to (d) are explanatory diagrams of a method for producing a photomask according to another example of the first embodiment. [Figure 6] 6(a) to (d) are explanatory diagrams continuing from FIG. [Figure 7] 7(a) to (d) are explanatory diagrams continuing from FIG. [Figure 8] Fig. 8(a) is an enlarged plan view of a main part of a photomask according to embodiment 2. Fig. 8(b) is a cross-sectional view taken along line BB in Fig. 8(a). [Figure 9] 9(a) to (d) are explanatory diagrams of a method for producing a photomask according to the second embodiment. [Figure 10] 10(a) to (d) are explanatory diagrams continuing from FIG. [Figure 11] 11(a) to (d) are explanatory diagrams continuing from FIG. [Figure 12] Fig. 12(a) is an enlarged plan view of a main part of a photomask according to embodiment 3. Fig. 12(b) is a cross-sectional view taken along line CC in Fig. 12(a). [Figure 13] 13(a) to (d) are explanatory diagrams of a method for producing a photomask according to the third embodiment. [Figure 14] 14(a) to (d) are explanatory diagrams continuing from FIG. [Figure 15] 15(a) to (d) are explanatory diagrams continuing from FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] <Configuration of the Photomask According to the First Embodiment> The configuration of the photomask according to the first embodiment will be described below.

[0019] As shown in FIG. 1, the photomask 1 is a three-tone multi-tone photomask having a transparent portion (white portion) 10, a light-shielding portion (black portion) 11, and a semi-transmitting portion (hatched portion) 12. The transparent portion 10 is composed of a transparent substrate 2. The light-shielding portion 11 is composed of a semi-transmitting film 3 as a lower layer film and a light-shielding film 4 as an upper layer film. The semi-transmitting portion 12 is composed of the semi-transmitting film 3. That is, the exposed portion of the transparent substrate 2 on which the semi-transmitting film 3 and the light-shielding film 4 are not laminated becomes the transparent portion 10, the portion on which the semi-transmitting film 3 and the light-shielding film 4 are laminated on the transparent substrate 2 becomes the light-shielding portion 11, and the portion on which only the semi-transmitting film 3 is formed on the transparent substrate 2 becomes the semi-transmitting portion 12.

[0020] The light-shielding portion 11 and the semi-transmitting portion 12 constitute the pattern of the photomask 1. The pattern is composed of a first region 11 and a second region 12. The first region 11 is a laminated portion of the semi-transmitting film 3 and the light-shielding film 4, and functions as the light-shielding portion 11. The second region 12 is a single layer portion of the semi-transmitting film 3, and functions as the semi-transmitting portion 12.

[0021] In this embodiment, lines (light-shielding portions 11) having widths in the order of μm and spaces (light-transmitting portions 10) having widths in the order of μm are arranged in parallel (and in some cases, these are repeated alternately), and the pattern of the photomask 1 is a line-and-space pattern. As an example, the pattern is used as a pattern for forming source-drain electrodes in a transfer substrate manufactured by photolithography using the photomask 1. In this case, the light-transmitting portions 10 function as channel portions, the light-shielding portions 11 function as electrode portions, and the semi-transmitting portions 12 function as rim portions of the light-shielding portions 11.

[0022] The rim portion 12 is provided in order to improve the process tolerance on the panel side. For example, the rim portion 12 is provided in order to make the edges of the resist pattern corresponding to the source / drain electrodes on the transfer substrate steeper. The width of the rim portion 12 is, for example, in the range of 0.1 μm or more, or 0.5 μm or more and 3.0 μm or less.

[0023] 1 and the following drawings, the semi-transmitting film 3 and the light-shielding film 4 are illustrated as being exaggeratedly thick. Also, in FIG. 1 and the following drawings, the light-shielding film 4 is illustrated as being thicker than the semi-transmitting film 3. However, this is for the sake of convenience, and the film thicknesses of the semi-transmitting film 3 and the light-shielding film 4 are set individually and appropriately.

[0024] The transparent substrate 2 is a substrate such as synthetic quartz glass. The transparent substrate 2 has a transmittance of 95% or more for a representative wavelength (for example, i-line, h-line, or g-line) contained in the exposure light used in the exposure step of photolithography. The exposure light may be, for example, i-line, h-line, or g-line, or may be a mixed light containing at least two of these lights. Alternatively, the exposure light may have a wavelength band shifted or expanded to the short wavelength side and / or long wavelength side compared to these lights. As an example, the wavelength band of the exposure light may be expanded from a broadband of 365 nm to 436 nm to 300 nm to 450 nm. However, the exposure light is not limited to these.

[0025] The semi-transparent film 3 is a kind of functional film having a function of adjusting the optical characteristics of the exposure light, and is a functional film having a function of changing the phase of the exposure light, that is, a phase shift film. The phase shift film is set so that the phase shift amount for the representative wavelength is approximately 180°. Approximately 180° means a value within the range of 180±20°, and more preferably, a value within the range of 180°±10°. In addition, the phase shift film has a transmittance for the representative wavelength contained in the exposure light that is lower than the transmittance of the transparent substrate 2 and higher than the transmittance of the light-shielding film 4, and is set so that the transmittance for the representative wavelength is 5% to 30%.

[0026] The semi-transparent film 3 is made of a metal silicide-based material selected from known materials such as Cr or a Cr-based compound (oxide, nitride, carbide, oxynitride, oxynitride carbide, etc. of Cr, the same applies below), Ni or a Ni-based compound (oxide, nitride, carbide, oxynitride, oxynitride carbide, etc. of Ni, the same applies below), Ti or a Ti-based compound (oxide, nitride, carbide, oxynitride, oxynitride carbide, etc. of Ti, the same applies below), a Si-based compound (oxide, nitride, carbide, oxynitride, oxynitride carbide, etc. of Si, the same applies below), Zr or a Zr compound (oxide, nitride, carbide, oxynitride, oxynitride carbide, etc. of Zr, the same applies below), a metal silicide compound (molybdenum silicide, tungsten silicide, tantalum silicide, zirconium silicide, or nitrides or oxynitrides thereof, the same applies below), etc. In this embodiment, the semi-transparent film 3 is made of a molybdenum silicide compound.

[0027] The light-shielding film 4 is a type of functional film having a function of adjusting the optical characteristics of the exposure light, and is a functional film having a function of blocking the exposure light. The light-shielding film 4 has a transmittance of 1% or less for a representative wavelength contained in the exposure light. Alternatively, the optical density (OD value) in the light-shielding portion 11 may be 2.7 or more. As an example, the light-shielding film 4 has a laminated structure including a first film-forming layer and a second film-forming layer. The first film-forming layer is made of a metal film and has a purpose of blocking light. The second film-forming layer is made of a metal oxide film and has a purpose of suppressing reflection. In this case, even if the transmittance of the first film-forming layer is higher than 1%, it is sufficient that the laminated transmittance of the first film-forming layer and the second film-forming layer is 1% or less.

[0028] The light-shielding film 4 is made of a Cr-based material among known materials such as Cr or a Cr-based compound, Ni or a Ni-based compound, Ti or a Ti-based compound, a Si-based compound, Zr or a Zr compound, and a metal silicide compound. In the present embodiment, a Cr-based compound is used for the light-shielding film 4. The reason for using a Cr-based compound is that a thin film made of a Cr-based compound has a suitable resistance to a cleaning process that is performed when a photomask is contaminated or has foreign matter attached thereto during a manufacturing process of a transfer substrate.

[0029] The semi-transmitting film 3 and the light-shielding film 4 are made of different materials and therefore have different etching characteristics. That is, the semi-transmitting film 3 has etching selectivity with respect to the light-shielding film 4, and the light-shielding film 4 has etching selectivity with respect to the semi-transmitting film 3.

[0030] <Method of Manufacturing Photomask According to Embodiment 1> Next, a method for manufacturing the photomask 1 according to the first embodiment will be described.

[0031] The manufacturing method includes: i) Photomask blanks preparation process (process 1) ii) First resist film formation process (process 2) iii) First drawing process (process 3) iv) First development process (process 4) v) First upper layer etching process (process 5) vi) First resist film removal process (process 6) vii) Second resist film formation process (process 7) viii) Second drawing process (process 8) ix)Second development process (Step 9) x) Second upper layer etching process (process 10) xi) Underlayer film etching process (step 11) xii) Second resist film removal process (process 12) Equipped with.

[0032] The steps from the resist film formation step (step 2) to the resist film removal step (step 6) and from the resist film formation step (step 7) to the resist film removal step (step 12) are referred to as patterning steps, respectively. In the former patterning step, the upper layer film (light-shielding film) 4 of the photomask blank is patterned, and in the latter patterning step, the lower layer film (phase shift film) 3 of the photomask blank is patterned.

[0033] In the photomask blanks preparation step (step 1), a photomask blank is prepared as shown in Fig. 2(a). In the photomask blanks, a lower layer film 3 is formed on a transparent substrate 2, and an upper layer film 4 is formed on the lower layer film 3, so that the lower layer film 3 and the upper layer film 4, which have different etching properties, are laminated on the transparent substrate 2. The lower layer film 3 and the upper layer film 4 are each formed by a physical vapor deposition (PVD) method such as a sputtering method or a deposition method.

[0034] In the first resist film formation step (step 2), as shown in FIG. 2(b), a resist is uniformly applied onto the upper layer film 4 to form a resist film 5. The resist is applied by a coating method, a spraying method, or the like. The resist may be either positive type or negative type, but in this example, a positive type is used.

[0035] In the first writing step (step 3), as shown in FIG. 2(c), the resist film 5 is irradiated with exposure light using an electron beam or laser of a writing device, and a first resist pattern is written. At this time, two regions with different exposure amounts are formed in the resist film 5. The first region 5a is an unexposed region. The second region 5b is an exposed region with a predetermined exposure amount. In the case of a negative resist, the relationship of the exposure amounts is opposite to that of a positive resist. In addition to writing the resist pattern, in the first writing step (step 3), a mark (alignment mark) for aligning the position of writing in the second writing step (step 8) is written. Although not shown, the alignment marks are formed, for example, at appropriate three or four places in the surrounding region surrounding the resist pattern.

[0036] In the first developing step (step 4), as shown in FIG. 2(d), the unnecessary resist film 5 (second region 5b) is developed and removed to form first resist patterns 5A and 5B. The first resist patterns 5A and 5B are patterns including a first pattern 5A corresponding to the first region 11 of the pattern of the photomask 1, and a second pattern 5B separated from the first pattern 5A and set at a position where the edge of the first pattern 5A side corresponds to the position of the edge of the second region 12 of the pattern of the photomask 1. The development is performed by a dipping method, a spin method, a paddle method, a spray method, or the like. The first resist film forming step (step 2), the first drawing step (step 3), and the first developing step (step 4) are collectively referred to as a first resist pattern forming step.

[0037] In the first upper layer film etching step (step 5), as shown in FIG. 3(a), the exposed portion of the upper layer film 4 is removed by etching using the first resist patterns 5A and 5B as an etching mask. The etching may be either dry etching or wet etching, but wet etching is preferable for a large-sized photomask. An etching solution or an etching gas is used as the etchant. Regardless of the etchant, an etchant having etching selectivity for the upper layer film 4 (an etchant that does not etch the lower layer film 3) is used. During etching, the upper layer film 4 is also side-etched. This is why the edge position of the upper layer film 4 is offset inward from the edge position of the first resist patterns 5A and 5B in the figure. However, depending on the film thickness of the upper layer film 4, the material of the upper layer film 4, or the type of etchant, side etching may not occur. The etching rate of the upper layer film 4 can be adjusted by adjusting the concentration, temperature, etching time, and other conditions under which the etchant is used. By adjusting the etching rate of the upper layer 4, it is possible to adjust the offset dimension to a desired value.

[0038] In the first resist film removal step (step 6), the remaining resist film 5 (first resist patterns 5A, 5B) is removed as shown in FIG. 3(b). The resist film 5 is removed by an ashing method, a dipping method, or the like. As a result, upper layer film patterns 4A, 4B are formed on the semipermeable membrane 3. The upper layer film patterns 4A, 4B are patterns including a first pattern 4A corresponding to a first region 11 of the pattern of the photomask 1, and a second pattern 4B spaced apart from the first pattern 4A and set at a position where an edge on the first pattern 4A side corresponds to the position of an edge of a second region 12 of the pattern of the photomask 1.

[0039] In the second resist film forming step (step 7), as shown in Fig. 3(c), a resist is applied onto the underlayer film 3 and the overlayer film 4 to form a resist film 5. The method itself is the same as that of the first resist film forming step (step 2).

[0040] In the second writing step (step 8), a second resist pattern is written on the resist film 5, as shown in Fig. 3(d). The method itself is the same as in the first writing step (step 3), and the writing device is the same as the writing device used in the first writing step (step 3). In the second writing step (step 8), the writing device detects the alignment mark formed in the surrounding area surrounding the pattern formation area of ​​the lower layer film in the first writing step (step 3), and aligns the transparent substrate 2.

[0041] However, the second resist pattern only needs to cover and protect the necessary areas, and does not require high positional accuracy of the pattern. Therefore, strict alignment is not required in the second drawing process (process 8).

[0042] However, in the second drawing process (step 8), misalignment inevitably occurs. Therefore, in the second drawing process (step 8), a second resist pattern is set taking misalignment into consideration. Specifically, the second resist pattern is designed to lap (overlap) the laminated portion of the lower layer film 3 and the upper layer film 4 by a predetermined lap amount from the edge of the laminated portion. The lap amount is, for example, a value of 0.3 μm or more and 0.5 μm or less.

[0043] In the second developing step (step 9), as shown in FIG. 4(a), the unnecessary resist film 5 (part 5b) is removed by development to form a second resist pattern 5C. The second resist pattern 5C is a pattern that covers the first pattern 4A of the upper layer film pattern, the exposed part of the lower layer film 3 between the first pattern 4A and the second pattern 4B of the upper layer film pattern, and at least the part including the edge on the first pattern 4A side of the second pattern 4B of the upper layer film pattern, and exposes at least a part of the other part of the second pattern 4B of the upper layer film pattern. The method itself is the same as that of the first developing step (step 4). The second resist film forming step (step 7), the second drawing step (step 8), and the second developing step (step 9) are collectively referred to as the second resist pattern forming step.

[0044] In the second upper layer film etching step (step 10), as shown in FIG. 4(b), the second pattern 4B of the upper layer film pattern is removed by etching. The method itself is the same as the first upper layer film etching step (step 5). In the second upper layer film etching step (step 10), the second pattern 4B of the upper layer film pattern is finally side-etched and completely removed. As a result, an edge (lower edge) is formed at the bottom of the second resist pattern 5C that coincides with the position of the edge of the second pattern 4B of the upper layer film pattern on the first pattern 4A side.

[0045] In the lower layer film etching step (step 11), as shown in FIG. 4(c), the exposed portion of the lower layer film 3 is removed by etching using the second resist pattern 5C (the lower edge of the second resist pattern 5C) as an etching mask. The etching may be either dry etching or wet etching, but wet etching is preferable for a large-sized photomask. An etching solution or an etching gas is used as the etchant. Regardless of the etchant, an etchant having etching selectivity for the lower layer film 3 (an etchant that does not etch the upper layer film 4) is used. During etching, the lower layer film 3 is also side-etched. This is why the position of the edge of the lower layer film 3 is offset inward from the position of the lower edge of the second resist pattern 5C in the figure. However, depending on the film thickness of the lower layer film 3, the material of the lower layer film 3, or the type of etchant, side etching may not occur. The etching rate of the lower layer film 3 can be adjusted by adjusting the concentration, temperature, etching time, and other conditions under which the etchant is used. By adjusting the etching rate of the underlayer film 3, it is possible to adjust the offset dimension to a desired value.

[0046] In the second resist film removal step (step 12), the remaining resist film 5 (second resist pattern 5C) is removed as shown in Fig. 4(d). The method itself is the same as that of the first resist film removal step (step 6).

[0047] Through the above steps 1 to 12, the photomask 1 is completed.

[0048] As described above, according to the method for manufacturing the photomask 1 of this embodiment, except for the drawing step (second drawing step (step 8)) in which the positional accuracy of the pattern is not important, the final required pattern dimensions can be determined in one drawing step (first drawing step (step 3)). This eliminates the need for excessive alignment accuracy in the manufacturing process of the photomask 1. Therefore, according to the method for manufacturing the photomask 1 of this embodiment, there is no alignment misalignment, and high definition photomask 1 can be achieved.

[0049] Furthermore, according to the method for manufacturing the photomask 1 of this embodiment, the position of the edge of the second region 12 of the pattern of the photomask 1 is determined based on the position of the edge of the second pattern 4B of the upper layer film pattern on the first pattern 4A side, not on the position of the edge of the second pattern 4B of the upper layer film pattern on the opposite side to the first pattern 4A. As a result, the width of the second pattern 4B of the upper layer film pattern is not a factor in setting the width of the second region 12. Therefore, according to the method for manufacturing the photomask 1 of this embodiment, it is possible to realize a photomask with even higher resolution than the conventional photomask manufacturing methods.

[0050] <Method of manufacturing a photomask according to another example of the first embodiment> 5 to 7, the method for manufacturing the photomask 1 according to the alternative embodiment of the present invention is substantially the same as the method for manufacturing the photomask 1 according to the embodiment 1, except that the width of the second pattern 4B of the upper layer film pattern is reduced within a range that is not affected by misalignment (see FIG. 6(b)). Therefore, the description of the method for manufacturing the photomask 1 according to the alternative embodiment of the present invention will be omitted, since it is the same as the description of the method for manufacturing the photomask 1 according to the embodiment 1.

[0051] <Configuration of the Photomask According to the Second Embodiment> As shown in Fig. 8, the pattern of the photomask 1 according to the second embodiment is a hole pattern having holes (transmitting portions 10) of a size in the order of µm (in some cases, these are arranged one-dimensionally or two-dimensionally at a predetermined interval). Therefore, in the photomask 1 according to the second embodiment, the transmitting portions 10 that become the hole pattern are formed in the underlayer film 3, and the second regions 12 are formed around them. The configuration of the photomask 1 according to the second embodiment is substantially the same as that of the photomask 1 according to the first embodiment, except for the difference in the shape of the pattern. Therefore, the description of the configuration of the photomask 1 according to the second embodiment will be omitted, since it is the same as the description of the configuration of the photomask 1 according to the first embodiment.

[0052] <Method of Manufacturing Photomask According to Second Embodiment> The method for producing the photomask 1 according to the second embodiment is as shown in Figs. 9 to 11, and is substantially the same as the method for producing the photomask 1 according to the first embodiment, except for the difference in the form of the pattern. Therefore, the description of the method for producing the photomask 1 according to the second embodiment is omitted, since it is the same as the description of the method for producing the photomask 1 according to the first embodiment. To supplement, in the photomask 1 according to the first embodiment, the first region 11 and the second region 12 are defined in the first drawing step, and the first region 11 functions as the light-shielding portion 11. In contrast, in the photomask 1 according to the second embodiment, the second pattern 4B of the upper layer film pattern is for defining the dimensions of the resist pattern for forming the hole pattern to be formed in the lower layer film 3, and is finally removed, and then the lower layer film 3 is removed using the resist pattern for forming the hole pattern as a mask, and the hole pattern is formed.

[0053] In this way, the method for manufacturing the photomask 1 according to the second embodiment also provides the same advantageous effects as those provided by the method for manufacturing the photomask 1 according to the first embodiment.

[0054] <Configuration of the Photomask According to the Third Embodiment> 12, the configuration of the photomask 1 according to embodiment 3 is substantially the same as that of the photomask 1 according to embodiment 1, except that the widths of the second regions (rim portions) 12, 12 on both sides are different (width A on the left side > width B on the right side). Therefore, a description of the configuration of the photomask 1 according to embodiment 3 will be omitted since it is the same as the description of the configuration of the photomask 1 according to embodiment 1.

[0055] <Method of Manufacturing Photomask According to Third Embodiment> 13 to 15, the method for manufacturing the photomask 1 according to the third embodiment is substantially the same as the method for manufacturing the photomask 1 according to the first embodiment, except that the widths of the resist removed portions on both sides are different (width a on the left side in FIG. 13(d)>width b on the right side). Therefore, the description of the method for manufacturing the photomask 1 according to the third embodiment will be omitted, as it is the same as the description of the method for manufacturing the photomask 1 according to the first embodiment.

[0056] In this way, the method for manufacturing the photomask 1 according to the third embodiment also provides the same advantageous effects as those provided by the method for manufacturing the photomask 1 according to the first embodiment.

[0057] Moreover, according to the method for manufacturing the photomask 1 of the third embodiment, by changing the positions of the second patterns 5B, 5B on both sides of the primary resist pattern (the second patterns 4B, 4B on both sides of the upper layer film pattern), the widths of the second regions (rim portions) 12, 12 on both sides can be set individually and arbitrarily. Therefore, according to the method for manufacturing the photomask 1 of the third embodiment, it is also possible to form an asymmetric pattern in which one second region (rim portion) 12 is larger in width and the other second region (rim portion) 12 is smaller in width.

[0058] The asymmetric pattern and manufacturing method of the third embodiment are not limited to the line and space pattern of the first embodiment, but can be applied to various patterns. For example, the third embodiment can be applied to the hole pattern of the second embodiment. In this case, the width of the resist removed portions on both sides can be made different in FIG. 9(d). Also, the width of the second region (rim portion) 12 can be made different not only in the left-right direction, but also in the up-down direction in FIG. 8(a). That is, the widths of the four sides of the hole can be set individually and arbitrarily.

[0059] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the gist of the present invention.

[0060] In the above embodiment, the second region 12 of the photomask pattern is a rim portion. However, the present invention is not limited to this. The second region may be another functional portion.

[0061] In the above embodiment, the rim portion 12 is formed on both sides of the light shielding portion 11. However, the present invention is not limited to this. The rim portion may be formed on only one side of the light shielding portion.

[0062] In the above embodiment, the lower layer film is a phase shift film. However, the present invention is not limited to this. The lower layer film may be a halftone film. The halftone film is a kind of functional film having a function of adjusting the optical characteristics of the exposure light, and is a functional film having a function of adjusting the transmittance of the exposure light. The halftone film has a transmittance lower than the transmittance of the transparent substrate and higher than the transmittance of the light-shielding film for the representative wavelength contained in the exposure light, and is set to have a transmittance of 10% to 70% for the representative wavelength. The halftone film is set so that the phase shift amount for the representative wavelength is less than 20°, more preferably less than 5°. The halftone film may be a semi-transmitting metal film in which the transmittance distribution in the plane of the photomask is improved by adjusting the nitrogen content. The halftone film can also change the optical density (OD value) in the semi-transmitting part by containing other elements. The advantage of using such a semi-transmitting film is that it has an effect of improving the process margin on the panel side.

[0063] In the above embodiment, the lower layer is a phase shift film, and the upper layer is a light-shielding film. However, the present invention is not limited to this. The lower layer may be a halftone film, and the upper layer may be a phase shift film. Alternatively, the lower layer may be a phase shift film, and the upper layer may be a halftone film. In these cases, the laminated portion of the lower layer and the upper layer may function as a light-shielding portion. In short, the lower layer and the upper layer are each selected from various functional films having the function of adjusting the optical properties of the exposure light, such as a light-shielding film, a phase shift film, and a halftone film, and a laminated structure of any combination of the lower layer and the upper layer can be adopted.

[0064] In the above embodiment, the lower layer is made of a metal silicide-based material, and the upper layer is made of a Cr-based material. However, the present invention is not limited to this. For example, the lower layer is made of a Cr-based material, and the upper layer is made of a metal silicide-based material. In other words, the lower layer and the upper layer have different etching characteristics, and can be selected from Cr-based materials, Ni-based materials, Ti-based materials, Si-based materials, Zr-based materials, or metal silicide-based materials, or from other materials, according to the corresponding transfer shape and part.

[0065] In the above embodiment, the structure is a two-layer structure of a lower layer film and an upper layer film. However, the present invention is not limited to this. As long as the layer structure is applicable to the photomask manufacturing method according to the present invention, cases in which other films are formed in addition to the lower layer film and the upper layer film are not excluded. For example, i) an intermediate film such as an etching stopper film may be formed at the interface between the upper layer film and the lower layer film. Alternatively, ii) another film may be formed on the upper surface of the upper layer film. In this case, the width of the second region is made wide in advance, and after the second resist film removal step (step 12) shown in FIG. 4(d), for example, a high-transmittance semi-transmitting film is formed and laminated on the upper layer of the second region. At this time, the high-transmittance semi-transmitting film is set to have a transmittance of 10% to 70% for the representative wavelength, and the phase shift amount is set to be less than 20°, more preferably less than 5°, so that the phase effect can be maintained at the transmitting side edge of the second region and the edge adjacent to the first region, and the laminated semi-transmitting film can adjust the laminated transmittance near the center of the second region. This allows the resist pattern formed on the transfer substrate to be formed with a thickness and shape according to the region to be formed. This improves the resolution by the phase effect, enables further finer patterns, and improves the process margin on the panel side in the lithography process such as a halftone mask. That is, a photomask capable of achieving both the halftone effect and the phase shift effect can be realized. When patterning this third highly transmissive semi-transmissive film, it can be realized by further performing a drawing process (secondary drawing process (process 8)) in which the positional accuracy of the pattern is not important according to the manufacturing method of the photomask 1 according to this embodiment. Even if misalignment occurs due to this drawing process, the influence on the phase effect is within an acceptable range at the edge of the transmissive part of the second region. In addition, the highly transmissive semi-transmissive film laminated on the upper layer of the first region is preferable because it suppresses even slight reduction in the thickness of the resist pattern formed on the transfer substrate to which the first region corresponds. In addition, the upper layer film may be replaced with the light-shielding film 4, and a semi-transmissive film may be laminated, and a functional thin film having the function of an anti-reflection film may be laminated on the upper layer.In this case, there is no change in the process of formation, but the first and second regions are determined in the first drawing process (process 3) shown in FIG. 2(c), and then the etching process is increased when patterning the functional thin film and the semi-transparent film. This can be realized by selecting a film having etching selectivity for the functional thin film and the upper film of the uppermost layer. In the case of this film configuration, a photomask that can achieve both the halftone effect and the phase shift effect described above can be realized, and by using the functional thin film as an etching mask in combination, it is possible to achieve etching with higher accuracy, so that the dimensional accuracy can be improved. In addition, since the phase shift film is laminated as the lower film and the semi-transparent film is laminated as the upper film in the first region, it is originally expected that the film thickness of the corresponding resist pattern on the transfer substrate will be reduced because some exposure light is transmitted through the film thickness, but the optical density OD of the functional thin film of the uppermost layer can be adjusted in advance to suppress the film reduction of the resist pattern formed on the corresponding transfer substrate. Alternatively, iii) another film may be formed on the lower surface of the lower film. That is, by forming an anti-reflection film as the bottom layer, the exposure light incident from the substrate side during exposure to the transfer substrate is reflected by the surface of the lower film, thereby preventing what could be called stray light.

[0066] In the above embodiment, the photomask pattern is a line and space pattern in which lines (light-shielding portion 11) having a width in the unit of μm and spaces (light-transmitting portion 10) having a width in the unit of μm are arranged in parallel in at least a part of the region (sometimes these are alternately repeated). Alternatively, in the above embodiment, the photomask 1 pattern is a hole pattern having holes (light-transmitting portion) having a size in the unit of μm in at least a part of the region (sometimes these are arranged one-dimensionally or two-dimensionally with a predetermined interval). However, the present invention is not limited to this. The photomask pattern may be a dot pattern having dots (light-shielding portion) having a size in the unit of μm in at least a part of the region (sometimes these are arranged one-dimensionally or two-dimensionally with a predetermined interval). Of course, other patterns may be used. In short, the type of pattern is not limited as long as it can be implemented by the method of the present invention.

[0067] In addition, in the above embodiment 2, the shape of the hole (transmissive portion 10) (the boundary line with the rim portion (semi-transmissive portion 12)) is rectangular, and the shape of the rim portion (semi-transmissive portion 12) (the boundary line with the light-shielding portion 11) is rectangular. However, the present invention is not limited to this. The shape of the hole and the shape of the rim portion may be other shapes, such as a circle or a polygon. Also, the shape of the hole and the shape of the rim portion may be different. [Explanation of symbols]

[0068] 1...photomask, 10...transmitting portion, 11...light-shielding portion (first region), 12...semi-transmitting portion (second region), 2...transparent substrate, 3...underlayer film (semi-transmitting film), 4...upperlayer film (light-shielding film), 4A...first pattern of upper layer film pattern, 4B...second pattern of upper layer film pattern, 5...resist film, 5a...first region, 5b...second region, 5A...first pattern of primary resist pattern, 5B...second pattern of primary resist pattern, 5C...second resist pattern

Claims

1. A method for manufacturing a photomask comprising: a lower layer film formed on a transparent substrate; and an upper layer film formed on the lower layer film so that at least a part of a peripheral region of the lower layer film is exposed; the photomask having a pattern constituted by a first region of a stacked portion of the lower layer film and the upper layer film and a second region of the lower layer film, a patterning step of removing unnecessary portions from an upper layer film of a photomask blank, which is formed by laminating a lower layer film and an upper layer film on a transparent substrate, while leaving a first pattern corresponding to a first region and a second pattern spaced apart from the first pattern, the second pattern having an edge on the first pattern side set at a position corresponding to the edge position of the second region and an edge on an opposite side to the first pattern; a resist pattern forming step of forming a resist pattern that covers the first pattern of the upper layer film pattern, the exposed portion of the lower layer film between the first and second patterns of the upper layer film pattern, and at least a portion of the second pattern of the upper layer film pattern that includes an edge on the first pattern side, and exposes at least a portion of the second pattern of the upper layer film pattern that includes an edge on the opposite side to the first pattern; a removing step of removing the second pattern of the upper layer film pattern; and an etching step of removing the lower layer film by etching so that the edge of the lower layer film is located closer to the second pattern than the edge of the first pattern of the upper layer film pattern on the second pattern side and closer to the first pattern than the edge of the second pattern on the side opposite to the first pattern. A method for manufacturing a photomask.

2. The lower and upper layers are formed of films in which the first region functions as a light-shielding portion and the second region functions as a phase-shifting portion. The method for manufacturing the photomask according to claim 1 .

3. A phase shift film is used as the underlayer film, A light-shielding film is used as the upper layer. The method for manufacturing a photomask according to claim 2 .

4. The second region functions as a rim portion of the light blocking portion. The method for manufacturing a photomask according to claim 2 .

5. After the lower layer film etching step, a step of laminating a highly transparent semi-transparent film on the lower layer film of the second region is included. The method for manufacturing the photomask according to claim 1 .

6. A laminated film of a semi-transparent film and an anti-reflection film is used as the upper layer film. The method for manufacturing the photomask according to claim 1 .

7. An underlayer film formed on a transparent substrate; an upper layer film formed on the lower layer film, a line-and-space pattern or a hole pattern configured from a first region that is a laminated portion of a lower layer film and an upper layer film, and a second region that is a single layer portion of the lower layer film where no upper layer film is laminated; The first region functions as a light blocking portion, the second region is a rim portion provided around the first region and functions as a phase shift portion; The second region provided on one side of the first region and the second region provided on the other side of the first region are provided to have different widths. Phase shift mask.

8. An underlayer film formed on a transparent substrate; an upper layer film formed on the lower layer film, a pattern including a first region which is a laminated portion of a lower layer film and an upper layer film, and a second region which is a single layer portion of the lower layer film where no upper layer film is laminated; The first region functions as a light blocking portion, the second region is a rim portion provided around the first region and functions as a phase shift portion; The width of the rim is 0.5 μm or less. Phase shift mask for panels.

Images