TW201830124A - Halftone mask, photomask blank, and method for manufacturing halftone mask - Google Patents

Abstract

To provide a halftone mask with which both a finer pattern and multi-gradation can be achieved. A first semitransparent region comprising a first semitransparent film, a second semitransparent region comprising a laminate of the first semitransparent film and a second semitransparent film, a transparent region, and a region in which the first semitransparent region and the second semitransparent region are adjacent to each other, are provided on a transparent substrate. The transmissivity of the first and second semitransparent regions with respect to exposure light respectively is 10-70% and 1-8%, and the second semitransparent region inverts the phase of the exposure light. Consequently, the intensity distribution of the exposure light changes sharply at the boundary portion of the adjacent first semitransparent region and second semitransparent region, enabling the cross-sectional shape of an exposed photoresist pattern to be improved.

Description

Half-tone mask, mask blank, and method for manufacturing half-tone mask

The invention relates to a multi-tone half-tone mask, a mask blank, and a method for manufacturing a half-tone mask. The half-tone mask is used in a flat panel display or the like.

In the technical field of flat-panel displays and the like, there has been used a multi-step dimming mask called a half-tone mask, which has a function of limiting the exposure amount with the transmittance of a semi-transmissive film. The half-tone mask can realize a multi-tone light-shielding mask of 3 colors or more by a transparent substrate, a light-shielding film, and a semi-transmissive film having a transmittance between the transparent substrate and the light-shielding film.

Patent Document 1 discloses a method for forming a half-tone mask, which processes a mask blank on which a light-shielding film has been formed on a transparent substrate, and after forming a pattern of the light-shielding film, a semi-transmissive film is formed, and then the light-shielding film is formed. Patterned with a semi-transmissive film to form a half-tone mask.

Such a half-tone mask is used, for example, in a manufacturing process of a liquid crystal display device to form a single exposure step in a channel region and a source / drain electrode formation region of a TFT (thin film transistor). The thickness of the photoresist pattern is different to reduce the lithography step.

On the other hand, in order to improve the image quality of a flat display, there is an increasing demand for miniaturization of wiring patterns. In the case where a pattern close to the resolution limit is to be exposed by a projection exposure machine, in order to ensure an exposure margin, Patent Document 2 discloses a phase shift mask which is provided to phase the edge portion of the light-shielding area. Reverse phase shifter.

[Prior Art Document] (Patent Document) Patent Document 1: Japanese Patent Application Laid-Open No. 2005-257712. Patent Document 2: Japanese Patent Application Laid-Open No. 2011-13283.

(Problems to be Solved by the Invention) In a half-tone mask, the intensity distribution of the exposure light at the boundary between the semi-transmissive film and the light-shielding film changes slowly. Therefore, a half-tone mask is used to expose the photoresist. The shape of the cross section at the boundary part of the boundary will show a gentle inclination, which will reduce the process margin, and as a result, it will be difficult to form a fine pattern.

By using a phase shift mask to improve the resolution, although the pattern can be further miniaturized, the lithography step cannot be reduced like a halftone mask. Therefore, when it is used in the manufacture of a flat panel display, it cannot contribute to reducing the manufacturing cost.

A gray pattern mask of a fine pattern type different from a halftone mask, although a relatively steep exposure light intensity distribution can be obtained between the light-shielding portion and the semi-transmissive portion, it has a problem that the depth of focus becomes shallow.

As described above, in the conventional photomask, the problem of reduction in manufacturing cost of a flat panel display and the like cannot be taken into consideration.

In view of the above-mentioned problems, an object of the present invention is to provide a photomask capable of both reducing the lithography step and further miniaturizing a pattern, and to provide a photomask blank and a method for manufacturing the photomask for manufacturing the photomask.

(Means for Solving the Problem) A photomask according to an embodiment of the present invention includes, on a transparent substrate, a first semi-transmissive region composed of a first semi-transmissive film and a second semi-transmissive region composed of the foregoing The first semi-permeable membrane and the second semi-permeable membrane are laminated; the transparent region does not include any of the first semi-permeable membrane and the second semi-permeable membrane; and the first semi-permeable membrane and the first semi-permeable membrane 2 The semi-transmissive region is adjacent to the region; wherein the transmittance of the first semi-transmissive region to the exposure light is 10 to 70%; the transmittance of the second semi-transmissive region to the exposure light is 1 to 8%, and the exposure light is The phase of the first semi-transmissive film and the second semi-transmissive film is reversed. When the phase shift angle of the first semi-transmissive film is α2, the phase shift angle of the semi-transmissive film is β180-α ≦ β ≦ 180.

In the photomask according to the embodiment of the present invention, the laminated film reverses the phase of the exposure light with respect to the first semi-transmissive region, or reverses the phase of the exposure light with respect to the transparent region.

Moreover, in the photomask according to the embodiment of the present invention, the phase shift angle α2 of the first semi-transmissive film and the phase shift angle β of the semi-transmissive film have a relationship of β = 180−α / 2.

By constructing such a photomask structure, a multi-level light-adjusting mask can be obtained, which has the gradation of the first semi-transmissive region, the second semi-transmissive region, and the transparent region, and further uses the second semi-transmissive region to control exposure light The phase reversal effect makes the change in the intensity distribution of the exposure light in the region adjacent to the first semi-transmissive region and the second semi-transmissive region steep. As a result, by using the photomask of the present invention, photoresists with different film thicknesses can be formed, and photoresists with steep cross-sectional shapes can be obtained.

In the photomask according to the embodiment of the present invention, the first semi-transmissive film and the second semi-transmissive film are each selective to each other's wet etching solution.

In the photomask according to the embodiment of the present invention, the first semi-transmissive film is selected from Ti (titanium), titanium oxide, titanium nitride, titanium oxynitride, or a multilayer film of two or more of these. In addition, the second semi-transmitting film is selected from self-oxidizing Cr (chromium), chromium nitride, chromium oxynitride, or a laminated film of two or more of these; or, as the first semi-transmissive film, being selected from chromium and oxidation Chromium, chromium nitride, chromium oxynitride, or two or more of these laminated films, and the second semi-permeable membrane is selected from auto-oxidized Ti (titanium), titanium nitride, titanium oxynitride, or two of these. More than one kind of laminated film.

With such a structure, necessary optical characteristics can be achieved for the first semi-transmissive film and the second semi-transmissive film, and a desired pattern can be easily formed.

In the photomask according to the embodiment of the present invention, in the laminated film, an edge of the second semi-transmissive film protrudes from a edge of the first semi-transmissive film by a predetermined size; and if the size is set to a wavelength of exposure light, Is λ, and if the number of openings of the optical system of the projection exposure apparatus that projects the exposure light is set to NA, it is set to λ / (8NA) or more and λ / (3NA) or less.

With such a structure, the exposure light intensity distribution at the boundary portion between the laminated film of the first semi-transmissive film and the second semi-transmissive film and the transparent substrate becomes steep, and a fine pattern can be formed.

A photomask according to an embodiment of the present invention includes a third semi-transmissive film, a fourth semi-transmissive film, and the third semi-transmissive film and the fourth semi-transmissive film which are sequentially laminated on a transparent substrate. Wherein, in the laminated film, the edge of the fourth semi-transmissive film protrudes from the edge of the third semi-transmissive film; the transmittance of the third semi-transmissive film to exposure light is 10 to 70%; and, The transmittance of the fourth semi-transmissive film to the exposure light is 2 to 9%, and the phase of the exposure light is reversed.

In the photomask according to the embodiment of the present invention, the fourth semi-transmissive film has a phase shift angle of approximately 1803. The semi-transmissive film reverses the phase of the exposure light, and makes the exposure light relative to the transparent substrate. Phase reversal.

In addition, a photomask according to an embodiment of the present invention includes a region composed of a laminated film in which the third semi-transmissive film and the fourth semi-transmissive film are sequentially laminated; and The area formed by the fourth semi-permeable membrane.

By using a pattern composed of such a region, for example, it is easy to achieve miniaturization of a channel region of a TFT and a wiring pattern of a peripheral circuit.

In the photomask according to the embodiment of the present invention, the third semi-transmissive film and the fourth semi-transmissive film are each selective to each other's wet etching solution.

In the photomask according to the embodiment of the present invention, the third semi-transmissive film is selected from Ti (titanium), titanium oxide, titanium nitride, titanium oxynitride, or a laminated film of two or more of these, and The fourth semi-transmissive film is selected from self-oxidized Cr (chromium), chromium nitride, chromium oxynitride, or a laminated film of two or more of these; or the third semi-transmissive film is selected from chromium, chromium oxide, Chromium nitride, chromium oxynitride, or two or more of these laminated films, and the fourth semi-permeable film is selected from auto-oxidized Ti (titanium), titanium nitride, titanium oxynitride, or two or more of these Laminated film.

With such a structure, necessary optical characteristics can be achieved for the third semi-transmissive film and the fourth semi-transmissive film, and a desired pattern can be easily formed.

The method for manufacturing the photomask according to the embodiment of the present invention includes the following steps: forming a first semi-transmitting film on a transparent substrate; forming a second semi-transmitting film on the first semi-transmitting film; and Forming a first photoresist on the semi-transmissive film; patterning the first photoresist; using the first photoresist as a mask, etching the second semi-transmitting film; removing the first photoresist; forming a second Photoresist; patterning the second photoresist; using the second photoresist as a mask; etching the first semi-transmissive film; and removing the second photoresist.

The method for manufacturing a photomask according to an embodiment of the present invention includes the following steps: forming a first semi-transmitting film on a transparent substrate; forming a second semi-transmitting film on the first semi-transmitting film; and 2 forming a first photoresist on the semi-transmissive film; patterning the first photoresist; using the first photoresist as a mask, etching the second semi-transmitting film; removing the first photoresist; forming a first 2 photoresist; patterning the second photoresist; using the second photoresist as a mask, side etching the first semi-transmissive film so that the end of the second semi-transmissive film extends from the first half The end portion of the transmissive film only protrudes by a predetermined range; and the second photoresist is removed.

The method for manufacturing a photomask according to an embodiment of the present invention includes the following steps: forming a third semi-transmitting film on a transparent substrate; forming a third photoresist on the third semi-transmitting film; Pattern the photoresist; use the third photoresist as a mask to etch the third semi-transparent film; remove the third photoresist; form a fourth semi-transparent film; form a fourth photoresist; The photoresist is patterned; the fourth semi-transmissive film is etched using the fourth photoresist as a mask; and the fourth photoresist is removed.

With such a method for manufacturing a photomask, it is possible to produce a photomask having both a halftone effect and a phase shift effect.

In the photomask blank of the embodiment of the present invention, a first semi-transmissive film and a second semi-transmissive film are sequentially laminated on a transparent substrate; the first semi-transmissive film has a transmittance of 10 to 70% for exposure light. ; The laminated film of the first semi-transmissive film and the second semi-transmissive film has a transmittance of 1 to 8% for exposure light, and the phase of the exposure light is reversed by the laminated film; and the laminated film, when The phase shift angle of the first semi-transmissive film is α2, and the phase shift angle of the semi-transmissive film is β: 180−α ≦ β ≦ 180.

By preparing such a mask blank, it is possible to shorten the manufacturing period of a mask capable of achieving both the halftone effect and the phase shift effect.

(Effects of the Invention) According to the present invention, it is possible to realize a photomask capable of achieving both a halftone effect and a phase shift effect, and it is also useful for reducing the number of steps in pattern miniaturization and lithography processing.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, the following embodiments do not limit the definition of the gist of the present invention. In addition, the same reference numerals are assigned to the same or the same members, and the description thereof is omitted.

(Embodiment 1) Hereinafter, the manufacturing process of Embodiment 1 of the photomask of this invention is demonstrated in detail.

As shown in FIG. 1 (A), a first semi-transmissive film 12 is formed on a transparent substrate 11 such as synthetic quartz glass by a sputtering method or the like, and a film is formed thereon by a sputtering method or the like. A second semi-transmissive film 13 made of a material different from that of the first semi-transmissive film 12 is used to prepare a photomask blank 10. Then, a first photoresist 14 is formed on the second semi-transmissive film 13 by a coating method.

By preparing the photomask blank 10 in advance, the manufacturing period of the photomask can also be shortened. Since the first semi-transmissive film 12 and the second semi-transmissive film 13 are different materials, they can be etched by using different etching solutions and have resistance to each other's etching solutions, so they can be selectively etched separately. .

For example, the first semi-transmissive film 12 can be selected from Ti (titanium), titanium oxide, titanium nitride, titanium oxynitride, or a laminated film of two or more of these, and the second semi-transmissive film 13 can be The self-oxidation Cr (chromium), chromium nitride, chromium oxynitride, or a laminated film of two or more of these are selected. In addition, as the first semi-transmissive film 12, self-oxidation can be selected from chromium, chromium oxide, chromium nitride, chromium oxynitride, or a laminated film of two or more of these, and as the second semi-transmissive film 13, self-oxidation can be selected. Titanium, titanium nitride, titanium oxynitride, or a laminated film of two or more of these. Moreover, the composition of the said oxide, a nitride, and an oxynitride may also change with respect to a film thickness direction.

As described later, the first semi-transmissive film 12 has a function as a half-tone film. Generally speaking, it is relatively easy to adjust the phase shift by using a Cr-based material. Therefore, the following is directed to the first semi-permeable film 12 made of the Ti-based material and the second semi-permeable film 13 made of the Cr-based material. An example will be described, but the above-mentioned film configurations may be interchanged.

The first semi-transmissive film 12 has a transmittance for exposure light of 10 to 70%. The transmittance of the second semi-transmissive film 13 to the exposure light is set so that the transmittance of the laminated film of the first semi-transmissive film 12 and the second semi-transmissive film 13 to the exposure light is 1 to 8%. The laminated film of the first semi-transmissive film 12 and the second semi-transmissive film 13 has a function as a phase shifter. Therefore, the film thickness of the second semi-transmissive film 13 is adjusted so that the phase of the exposure light is inverted. Determines the phase offset angle. The so-called phase reversal of the exposure light means that the phase shift angle of the exposure light is about 180 180 180 ± 10

In addition, as the exposure light, it is possible to use g-rays, h-rays, i-rays, or a mixture of two or more of these rays. In the mixed wavelength, the transmittance and the center-of-gravity wavelength of the representative wavelength or spectral distribution are defined. Phase shift.

The phase shift angle of the single-layer film of the second semi-transmissive film 13 is about 1801. The phase shift angle of the transmitted light of the semi-transmissive film 12 and the transmitted light of the laminated film of the first semi-transmissive film 12 and the second semi-transmissive film 13 are about 1801. The phase shift is about 180, and it is hereinafter referred to as a first phase shift condition for convenience.

The phase shift angle of the laminated film of the first semi-transmissive film 12 and the second semi-transmissive film 13 is a condition that the exposure light is reversed relative to the area exposed by the transparent substrate 11, that is, if the first semi-transmissive film 12 is When the phase difference between the transmitted light with respect to the transparent substrate 11 is α, and when the phase difference between the second semi-transmissive film 13 and the transmitted light with the transparent substrate 11 is β, α + β becomes a phase shift condition of approximately 1802. .

The transmittance and the phase shift angle can be adjusted by the material and film thickness of the films used in the first semi-transmissive film 12 and the second semi-transmissive film 13.

Next, as shown in FIG. 1 (B), for example, the first photoresist 14 is exposed by a mask drawing device, and then the first photoresist patterns 14a, 14b, and 14c are formed by development.

Next, as shown in FIG. 1 (C), using the first photoresist patterns 14a, 14b, and 14c as a mask, the second semi-transmissive film 13 is selectively etched away from the first semi-transmissive film 12 to form The patterns 13a, 13b, and 13c of the second semi-transmissive film are then removed by an ashing process or the like to remove the first photoresist patterns 14a, 14b, and 14c.

The etching method of the second semi-transmissive film 13 may be a wet etching method or a dry etching method as long as a sufficient selection ratio can be obtained, but a wet etching method capable of obtaining a high selection ratio is more suitably used. When the second semi-permeable membrane 13 is formed using a Cr-based material, a cerium-based etching solution such as an aqueous cerium ammonium nitrate solution is suitable, but is not limited thereto.

Next, as shown in FIG. 1 (D), a second photoresist 15 is formed by a coating method.

Next, as shown in FIG. 1 (E), the second photoresist 15 is exposed, and then the second photoresist patterns 15a and 15b are formed by development.

Next, as shown in FIG. 2, using the second photoresist patterns 15 a and 15 b as a mask, the first semi-transmissive film 12 is etched to form the patterns 12 a and 12 b of the first semi-transmissive film, and then subjected to ashing treatment. The second photoresist patterns 15a and 15b are removed. The first semi-transmissive film 12 may be etched by a wet etching method or a dry etching method, but a wet etching method capable of obtaining a high selectivity is more suitable. As the first semi-permeable membrane 12, when a material different from the material of the second semi-permeable membrane 13, such as a Ti-based material, is used, a mixed solution of potassium hydroxide (KOH) and an aqueous hydrogen peroxide solution is preferably used, but Not limited to this.

As shown in FIG. 2, on the transparent substrate 11, there are the following areas: the area C of the single-layered film of the first semi-transmissive film 12; and the pattern of the first semi-transmissive film 12 a and the pattern of the second semi-transmissive film. Areas A and B of the laminated film of 13a and 13b and adjacent to the area C; and area D of the laminated film of the pattern of the first semi-transmissive film 12b and the pattern of the second semi-transmissive film 13c not adjacent to the area C . Hereinafter, a region of the single-layered film of the first semi-transmissive film 12 is referred to as a first semi-transmissive region, and a region where the first semi-transmissive film 12 and the second semi-transmissive film 13 are laminated is referred to as a second semi-transmissive region.

In the second semi-transmissive region (regions A, B, and D), the transmittance of the exposure light is 1 to 8%, and the phase of the exposure light is reversed. On the other hand, in the first semi-transmissive region (region C), the transmittance of the exposure light is 10 to 70%. The regions other than the first semi-transmissive region and the second semi-transmissive region are regions E, F, and G (hereinafter sometimes referred to as transparent regions) where the transparent substrate 11 is exposed, and the transmittance is 100%. The first semi-transmissive region has a transmittance in the middle of the transmittance of the transparent region and the transmittance of the second semi-transmissive region, and becomes a multi-tone mask.

In the first phase shift condition, that is, the phase shift angle of the single-layer film of the second semi-transmissive film 13 is about 180C and the boundary portion between the regions A and B, the change in the intensity distribution of the transmitted exposure light becomes steep. Therefore, the cross-sectional shape of the photoresist exposed by the present mask changes abruptly at a position corresponding to the boundary portion. For example, in the case where the channel region of the TFT is formed in the region C, and the source and drain electrodes are formed in the regions A and B, the channel length can be accurately controlled, and the size design of the TFT is compared with the use of the previous photomask In this case, the design margin (margin) can be increased, and a fine TFT can be manufactured.

The region D is a region having no boundary with the semi-transmissive region, and this region can be used for, for example, exposure of wiring of peripheral circuits.

In the second phase shift condition, that is, the phase shift angle of the laminated film of the first semi-transmissive film 12 and the second semi-transmissive film 13 with respect to the transparent region is about 180E and the boundary of the region A, and the boundary between the region F and the region B. In the realm of the realm, the areas F, G, and D, the phase is reversed, so the change in the exposure light intensity distribution at these realms becomes steep. Therefore, the cross-sectional shape of the photoresist exposed by the photomask also becomes a steep shape at a position corresponding to these realms. As a result, a fine pattern can be formed. For example, when the miniaturization of wiring is a priority in peripheral circuits such as a flat display, a second phase shift condition may be adopted.

Moreover, by creating a state intermediate between the first phase shift condition and the second phase shift condition, both effects can be obtained. The effect of improving the resolution caused by the phase shift is as long as it is β = 180 with a phase shift condition of about 180101 and the second phase shift condition is α + β = 180. The phase shift angle α is about 20 (when the material is a Cr-based flat halftone film and the transmittance is 15% or more, or when the material is a Cr-based ordinary halftone film and the transmittance is 45% or more ), By making the phase shift angle β of the second semi-transmissive film between the first phase shift condition and the second phase shift condition, that is, 180-α ≦ β ≦ 180, or more preferably β = 180－α / 2, which can get the effect of both sides. For example, when α = 20β = 170, since α + β = 190, both β and α + β fall within the range of 180 ± 10. Under such phase shift conditions, the intensity distribution of the exposure light becomes steep at all boundaries, so the profile shape of the exposed photoresist becomes a steep shape in any boundary. In addition, the phase shift angles α and β are generally not negative because they are phase differences with respect to air, and α in reality (even in the case where the transmittance is 10% of the lower limit) is the highest. It will only go to 82β and not become negative.

In addition, the Cr-based flat halftone film refers to a film containing Cr (chromium) as a main component and contains a trace amount of oxygen and nitrogen, while the Cr-based ordinary halftone film refers to Cr (chromium) oxide as Film of main ingredients.

Figure 3 compares the shape of the photoresist exposed by this embodiment with the shape of the photoresist exposed by the previous mask. This embodiment combines a half-tone film and a phase shift. Transfer film, the previous photomask combines a halftone film and a light-shielding film that does not allow exposure light to pass through.

Fig. 3 (a) is a cross-section of a photomask of this embodiment, and Fig. 3 (a) is an enlarged view of a part of Fig. 2. FIG. 3 (b) is a part of a cross section of a conventional photomask disclosed in Patent Document 1. A pattern 42 of a light-shielding film is formed on a transparent substrate 41, and a halftone film is formed on the pattern 42 of the light-shielding film. Pattern 43.

FIG. 3 (c) schematically shows the cross-sectional shape of the photoresist 30 exposed by the photomask shown in FIG. 3 (a). The thickness of the photoresist film at a position corresponding to the half-tone film, that is, the first semi-transmissive film 12a is thinner than that of the photoresist film at the position of the second semi-transmissive film 13a, which is equivalent to the phase shift film, One photomask is used to form regions with different photoresist film thicknesses in one exposure. In FIG. 3 (c), a point P indicated by a black dot indicates a position corresponding to the boundary between the halftone film and the phase shift film.

Similarly, it is possible to form a photoresist 40 having a region with a different film thickness with a single exposure using the previous photomask. Fig. 3 (d) schematically shows the cross-sectional shape of the photoresist 40 exposed by the photomask shown in Fig. 3 (b). A point Q indicated by a black dot in FIG. 3 (d) indicates a position corresponding to the boundary between the halftone film and the light-shielding film.

FIG. 3 (e) is a graph showing the calculated values of the inclination angles at the points P and Q of each of the photoresists 30 and 40 by simulation and comparing them. The phase shift angle of the phase shift film, that is, the second semi-transparent film is 1805%, and the phase shift angle of the half-tone film, that is, the first semi-transparent film, is 254%, while meeting the first phase shift condition and the first 2 Both of these are phase offset conditions. In addition, the transmittance of the light-shielding film of the conventional photomask shown in FIG. 3 (b) is 0%, and it has no effect of phase shift.

It can be clearly understood from FIG. 3 (e) that the inclination angle of the point P of the photomask of this embodiment is larger than the inclination angle of the point Q of the previous photomask, and the cross section of the boundary portion of the photoresist 30 The shape becomes steep. That is, it can be understood that the cross-sectional shape of the photoresist can be improved by this embodiment.

(Embodiment Mode 2) The photomask blank 10 used in Embodiment Mode 1 can be used, and a second semi-transmissive film 13 can be formed around the laminated area of the first semi-transmissive film 12 and the second semi-transmissive film 13 Single-layer film. Due to the effect of reversing the exposure light caused by the second semi-transmissive film 13, the intensity distribution of the exposure light at the boundary between the laminated region of the first semi-transmissive film 12 and the second semi-transmissive film 13 and the exposed area of the transparent substrate 11 It changes steeply, so the cross-sectional shape of the corresponding photoresist becomes steep.

As shown in FIG. 4 (A), after the step in FIG. 1 (E), the second photoresist patterns 15a and 15b are used as a mask, and the first semi-transmittance is selectively etched away from the second semi-transmissive film. Film 12. At this time, side etching is performed from the stage where the side surface of the first semi-transmissive film 12 has been exposed, thereby forming the second photoresist patterns 15a and 15b and the patterns 13a, 13b, and 13c with respect to the second semi-transmissive film. Patterns 12c, 12d of the first semi-transmissive film. Such etching can be achieved by isotropic etching, and a wet etching method or a dry etching method can be used, but a wet etching method with a relatively high selection is more suitable.

Since the etching at this time has an etching selectivity with respect to the second semi-transmissive film, the second photoresist pattern need only cover at least an area where only the first semi-transmissive film is exposed. Therefore, the width of the second photoresist patterns 15a and 15b can be adjusted by taking the alignment error of the mask drawing device into consideration, for example, narrowing them.

Then, as shown in FIG. 4 (B), the second photoresist patterns 15a and 15b are removed by an ashing method. As shown in FIG. 4 (B), the patterns 13a and 13b of the second semi-transmissive film protrude a distance Z from the pattern 12c of the first semi-transmissive film toward the side of the region exposed by the transparent substrate 11, and the second semi-transmissive film The pattern 13c of the film protrudes by a distance Z from the pattern 12d of the first semi-transmissive film toward the side of the region where the transparent substrate 11 is exposed. The size of Z can be controlled by the amount of side etching, such as wet etching time.

In this way, by controlling the size of Z by the etching process, the first semi-transmissive film patterns 12c and 12d can be formed in an automatic alignment manner without the occurrence of misalignment, so the second semi-transmissive film pattern can be formed. The phase shift effect is made uniform.

By setting the phase shift angles of the patterns 13a, 13b, and 13c of the second semi-transmissive film to the conditions where the exposure light is reversed relative to the area exposed by the transparent substrate 11, the phase shift angle is set to about 180 (180 ± 10), the boundary between the area where the patterns 13a, 13b of the second semi-transmissive film and the pattern 12c of the first semi-transmissive film are laminated and the area where the transparent substrate 11 is exposed, and the pattern 13c of the second semi-transmissive film and the first In the boundary between the area where the pattern 12d of the semi-transmissive film is laminated and the area where the transparent substrate 11 is exposed, the intensity distribution of the exposure light changes abruptly. As a result, the cross-sectional shape of the exposed photoresist also becomes steep.

If the size of the above-mentioned Z is too large, the pattern formed by the laminated film of the pattern 12d of the first semi-transmissive film and the pattern 13c of the second semi-transmissive film becomes unnecessarily thin and sometimes becomes a defect (broken line). 2. Causes of poor circuit. The size of Z is set to λ / (8NA) and λ / if the number of openings of the optical system of the projection exposure device using a photomask is NA and the wavelength (representative wavelength) of the exposure light is λ. (3NA) or less.

(Embodiment Mode 3) In Examples 1 and 2, a laminated film of a first semi-transmissive film 12 as a halftone film and a second semi-transmissive film 13 as a phase shifter is formed, and then patterned. However, it is also possible to form a pattern of the phase shifter film after forming the pattern of the half-tone film, thereby manufacturing a photomask. According to this embodiment mode, a single-layer film of a phase shifter can be formed at the edge portion of the halftone film, and the phase shift angle can be easily controlled.

As shown in FIG. 5 (A), a third semi-transmissive film 22 is formed on the transparent substrate 11 by a sputtering method or the like, a photomask blank 20 is prepared, and then a third semi-transmissive film 22 is formed by a coating method. A third photoresist 23 is formed on it. The third semi-transmissive film 22 has a function as a half-tone film, and has a transmittance for exposure light of 10 to 70%. For example, as the third semi-transmissive film 22, titanium, titanium oxide, titanium nitride, titanium oxynitride, or a laminated film of two or more of these, or chromium, chromium oxide, chromium nitride, chromium oxynitride, or Two or more of these are laminated films.

Next, as shown in FIG. 5 (B), for example, the third photoresist 23 is exposed by a mask drawing device, and then the third photoresist patterns 23a and 23b are formed by development.

Next, as shown in FIG. 5 (C), using the third photoresist patterns 23a and 23b as a mask, the third semi-transmissive film 22 is etched to form the patterns 22a and 22b of the third semi-transmissive film. The third photoresist patterns 23a and 23b are removed by an ashing process or the like.

Next, as shown in FIG. 5 (D), a fourth semi-transmissive film 24 made of a material different from the third semi-transmissive film 22 is formed by a sputtering method or the like, and then a fourth light is formed by a coating method. Resistance 25. The fourth semi-transmissive film 24 has a function as a phase shifter, and has a transmittance of 2 to 9% for exposure light. For example, as the third semi-transmissive film 22, titanium, titanium oxide, titanium nitride, titanium oxynitride, or a laminated film of two or more of these can be selected, and as the fourth semi-transmissive film 24, self-chromium oxide, Chromium nitride, chromium oxynitride, or a laminate of two or more of these. For example, as the third semi-transmissive film 22, self-oxidation can be selected from chromium, chromium oxide, chromium nitride, chromium oxynitride, or a laminated film of two or more thereof, and as the fourth semi-transmissive film 24, self-oxidation can be selected. Titanium, titanium nitride, titanium oxynitride, or a laminated film of two or more of these.

Next, as shown in FIG. 5 (D), the fourth photoresist 25 is exposed, and then the fourth photoresist patterns 25a, 25b, and 25c are formed by development.

Next, as shown in FIG. 6, using the fourth photoresist patterns 25a, 25b, and 25c as a mask, the fourth semi-transmissive film 24 is selectively etched with respect to the patterns 22a, 22b of the third semi-transmissive film to form a first The patterns of the semi-transparent film 24a, 24b, and 24c, and the fourth photoresist patterns 25a, 25b, and 25c are removed by ashing.

As shown in FIG. 6, the photomask includes the following areas: an area K composed of a single layer of the third semi-transmissive film 22; and an area I, M composed of a single layer of the fourth semi-transmissive film 24. ; Regions J, L, and O formed of a laminate of the third semi-transmissive film 22 and the fourth semi-transmissive film 24; and regions H, N, and P of the transparent substrate 11 that are exposed.

The phase shift angle of the fourth semi-transmissive film 24 is set to a condition that the phase of the exposure light is reversed relative to the third semi-transmissive film 22, that is, the phase shift angle is set to about 180 (180 ± 10) (called (This is the third phase shift condition.) In the boundary between the region K and the regions J and L, the intensity distribution of the exposure light changes abruptly, and the cross-sectional shape of the exposed photoresist also changes abruptly, so that fine patterns can be achieved. Into. For example, the region K can be used as a channel region of a TFT, and the regions J and L can be used as source and drain electrode regions.

The phase shift angle of the fourth semi-transmissive film 24 is set to a condition that the phase of the exposure light is reversed relative to the area exposed by the transparent substrate 11, that is, the phase shift angle is set to about 180 (180 ± 10) (called (The fourth phase shift condition), the intensity distribution of the exposure light changes sharply at the boundary portion between the regions I and M composed of the single layer of the fourth semi-transmissive film 24 and the regions H and N exposed by the transparent substrate 11 In addition, the cross-sectional shape of the exposed photoresist also changes abruptly, and the pattern can be miniaturized. As a result, the intensity distribution of the exposure light in the regions between the regions J and L and the regions H and N abruptly changes, and the cross-sectional shape of the corresponding photoresistors becomes steep.

By creating conditions that can satisfy both the third phase shift condition and the fourth phase shift condition, the intensity distribution of the exposure light becomes steep in all realms, so the profile shape of the exposed photoresist is also in the realm part. It becomes steep and the pattern can be made finer. For example, the phase shift angle of the third semi-transmissive film 22 with respect to the transparent substrate is set to a small angle, such as 0.4 to 10, which is not laminated with the third semi-transmissive film 22 and the fourth semi-transmissive film 24. The isolated region O adjacent to the region can be used for a wiring pattern such as a peripheral circuit, and it is easy to achieve both TFT and wiring miniaturization.

In addition, by making the widths of the regions I and M composed of a single layer of the fourth semi-transmissive film 24 below the resolution limit, the adverse effects of these regions I and M on the photoresist pattern can be eliminated. Specifically, it is preferable to make the width of the regions J and L approximately 0.5 mm in consideration of the alignment accuracy (positional deviation of the third and fourth photoresist patterns) of the mask drawing device. If it is such a size, compared with the resolution limit of a projection exposure apparatus, it will be sufficiently small, and the development effect of a photoresist by exposure light will not be produced, and the bad influence of these areas can be suppressed.

(Embodiment Mode 4) As shown in FIG. 7, the film configuration of the region O may be a single-layer structure of the fourth semi-transmissive film 24. The single-layer structure of the fourth semi-transmissive film 24 can be formed by patterning the third semi-transmissive film 22 without forming the third photoresist 23b in the step of FIG. 5 (B). With the phase shift angle of the fourth semi-transmissive film 24 without the third semi-transmissive film 22 alone, the phase shift angle from the transparent substrate 11 in the region O can be set to about 180 (180 ± 10), In addition, the pattern can be miniaturized. Such a single-layer film of the fourth semi-transmissive film 24 can be used for, for example, a wiring pattern of a peripheral circuit.

(Industrial Applicability) According to the present invention, it is possible to provide a photomask capable of reducing lithography steps and miniaturizing a pattern, and is extremely industrially applicable.

10‧‧‧Mask blank

11‧‧‧ transparent substrate

12‧‧‧The first semi-permeable membrane

12a, 12b, 12c, 12d ‧‧‧ The pattern of the first semi-transmissive film

13‧‧‧The second semi-permeable membrane

13a, 13b, 13c‧‧‧The pattern of the second semi-transmissive film

14‧‧‧1st photoresist

14a, 14b, 14c‧‧‧The first photoresist pattern

15‧‧‧2nd photoresist

15a, 15b ‧‧‧ 2nd photoresist pattern

20‧‧‧Mask blank

22‧‧‧The third semi-permeable membrane

22a, 22b ‧‧‧ The pattern of the third semi-permeable membrane

23‧‧‧3rd photoresist

23a, 23b‧‧‧3rd photoresist pattern

24‧‧‧The fourth semi-permeable membrane

24a, 24b, 24c ‧‧‧ The pattern of the fourth semi-transmissive film

25‧‧‧4th photoresist

25a, 25b, 25c ‧‧‧ 4th photoresist pattern

30‧‧‧Photoresist

40‧‧‧Photoresist

41‧‧‧ substrate

42‧‧‧ Pattern of light-shielding film

43‧‧‧ pattern of halftone film

FIG. 1 is a cross-sectional view showing the main manufacturing steps of a photomask according to a first embodiment of the present invention. Fig. 2 is a cross-sectional view showing the main manufacturing steps of a photomask according to a first embodiment of the present invention. FIG. 3 is a comparison diagram of the cross-sectional shape of a photoresist exposed by a photomask according to the first embodiment of the present invention and a conventional halftone photomask. FIG. 4 is a cross-sectional view showing the main manufacturing steps of a photomask according to a second embodiment of the present invention. Fig. 5 is a cross-sectional view showing the main manufacturing steps of a photomask according to a third embodiment of the present invention. Fig. 6 is a sectional view showing a photomask according to a third embodiment of the present invention. Fig. 7 is a cross-sectional view showing the main manufacturing steps of a photomask according to a fourth embodiment of the present invention.

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Claims (15)

A photomask on a transparent substrate includes: a first semi-transmissive region composed of a first semi-transmissive film; and a second semi-transmissive region formed by laminating the aforementioned first semi-transmissive film and a second semi-transmissive film. A transparent region in which neither of the first semi-transmissive film and the second semi-transmissive film exists; and a region where the first semi-transmissive region and the second semi-transmissive region are adjacent; wherein the first semi-transmissive region The transmission area has a transmittance of 10 to 70% for the exposure light; the second semi-transmission area has a transmittance of 1 to 8% for the exposure light and reverses the phase of the exposure light; and the first semi-transmissive film When the phase shift angle of the first semi-transmissive film and the laminated film of the second semi-transmissive film is α2, the phase shift angle of the semi-transmissive film is β: 180-α ≦ β ≦ 180. The photomask according to claim 1, wherein the laminated film reverses a phase of the exposure light with respect to the first semi-transmissive region or a phase of the exposure light with respect to the transparent region. The photomask according to claim 1 or 2, wherein the phase shift angle α2 of the first semi-transmissive film is the phase shift angle β β of the semi-transmissive film = 180−α / 2. The photomask according to any one of claims 1 to 3, wherein each of the first semi-transmissive film and the second semi-transmissive film is selective to each other's wet etching solution. The photomask according to any one of claims 1 to 4, wherein the first semi-transmissive film is selected from titanium, titanium oxide, titanium nitride, titanium oxynitride, or a laminate of two or more of these. And the second semi-transmissive film is selected from chromium oxide, chromium nitride, chromium oxynitride, or a laminated film of two or more of these; or, as the first semi-transmissive film, selected from chromium and chromium oxide , Chromium nitride, chromium oxynitride, or two or more of these laminated films, and the second semi-permeable film is selected from titanium oxide, titanium nitride, titanium oxynitride, or two or more of these laminated films membrane. The photomask according to any one of claims 1 to 5, wherein, in the laminated film, the edge of the second semi-transmissive film protrudes from the edge of the first semi-transmissive film by a predetermined size; The wavelength of the exposure light is set to λ, and the number of openings of the optical system of the projection exposure device that projects the exposure light is set to NA, and is set to λ / (8NA) or more and λ / (3NA) or less. A photomask includes a third semi-transmissive film, a fourth semi-transmissive film, and a laminated film in which the third semi-transmissive film and the fourth semi-transmissive film are sequentially laminated on a transparent substrate; In the film, an edge of the fourth semi-transmissive film protrudes from an edge of the third semi-transmissive film; the third semi-transmissive film has a transmittance of 10 to 70% for exposure light; and the fourth semi-transmissive film, The transmittance of the exposure light is 2 to 9%, and the phase of the exposure light is reversed. The photomask according to claim 7, wherein the fourth semi-transmissive film has a phase shift angle of approximately 1803 and the semi-transmissive film reverses the phase of the exposure light and makes the phase of the exposure light relative to the transparent substrate. reverse. The photomask according to claim 7 or 8, which has the following area: an area composed of a laminated film in which the third semi-transmissive film and the fourth semi-transmissive film are sequentially laminated; and A region formed by the fourth semi-permeable membrane. The photomask according to any one of claims 7 to 9, wherein each of the third semi-permeable membrane and the fourth semi-permeable membrane is selective to each other's wet etching solution. The photomask according to any one of claims 7 to 10, wherein the third semi-transmissive film is selected from titanium, titanium oxide, titanium nitride, titanium oxynitride, or a laminated film of two or more of these And the fourth semi-permeable membrane is selected from chromium oxide, chromium nitride, chromium oxynitride, or a laminated film of two or more of these; or the third semi-permeable membrane is selected from chromium, chromium oxide, and nitrogen Chromium oxide, chromium oxynitride, or two or more of these laminated films, and the fourth semi-permeable membrane is selected from titanium oxide, titanium nitride, titanium oxynitride, or two or more of these laminated films. A method for manufacturing a photomask, which is the method for manufacturing a photomask according to claim 1, and has the following steps: forming a first semi-transmitting film on a transparent substrate; and forming a second semi-transmitting film on the first semi-transmitting film A transmissive film; forming a first photoresist on the second semitransparent film; patterning the first photoresist; using the first photoresist as a mask to etch the second semitransparent film; removing the first 1 photoresist; forming a second photoresist; patterning the second photoresist; using the second photoresist as a mask to etch the first semi-transmissive film; and removing the second photoresist. A method for manufacturing a photomask, which includes the following steps: forming a first semi-transmitting film on a transparent substrate; forming a second semi-transmitting film on the first semi-transmitting film; and forming a first semi-transmitting film on the second semi-transmitting film Photoresist; patterning the first photoresist; using the first photoresist as a mask; etching the second semi-transmissive film; removing the first photoresist; forming a second photoresist; The photoresist is patterned; the second photoresist is used as a mask, and the first semi-transmissive film is side-etched so that the end portion of the second semi-transmissive film protrudes only from the end of the first semi-transmissive film. The size of the range; and the aforementioned second photoresist is removed. A method for manufacturing a photomask, which includes the following steps: forming a third semi-transmissive film on a transparent substrate; forming a third photoresist on the third semi-transmitting film; patterning the third photoresist; The third photoresist is used as a mask to etch the third semitransparent film; remove the third photoresist; form a fourth semitransparent film; form a fourth photoresist; pattern the fourth photoresist; The fourth photoresist is used as a mask to etch the fourth semi-transmissive film; and removing the fourth photoresist. A photomask blank, in which a first semi-transmissive film and a second semi-transmissive film are sequentially laminated on a transparent substrate; the first semi-transmissive film has a transmittance of 10 to 70% for exposure light; The laminated film of the film and the second semi-transmissive film has a transmittance of 1 to 8% for exposure light, and the phase of the exposed light is reversed by the laminated film; and, when the laminated film is the first semi-transmissive film, The phase shift angle of α is the relationship between β2 and the phase shift angle of the semi-transmissive film is β: 180−α ≦ β ≦ 180.