JP6259508B1 - Halftone mask, photomask blank, and method of manufacturing halftone mask - Google Patents

Abstract

A multi-tone halftone mask capable of exposing a fine photoresist pattern is provided. A transparent substrate includes a semi-transmissive portion made of a semi-transmissive film pattern and a phase shift portion made of a phase-shift film pattern. The phase shift film reverses the phase of the exposure light, The transmittance of the phase shift film is lower than the transmittance of the semi-transmissive film. Also, a semi-transmissive film, a laminated film of a phase shift film and an etching stopper film are formed at a boundary portion where the semi-transmissive part and the phase shift part are adjacent to each other. It is made of a material that is not etched by the etching solution. As a result, a photomask having both a halftone effect and a phase shift effect is realized. [Selection] Figure 3

Description

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

In a technical field such as a flat panel display, a multi-tone photomask called a halftone mask having a function of limiting an exposure amount by the transmittance of a semi-transmissive film is used.
The halftone mask uses a transflective film having an intermediate transmittance between the transparent substrate and the light shielding film, and a multi-tone photomask having three or more gradations is formed by the transparent substrate, the semitransmissive film, and the light shielding film. Can be realized.

By using a halftone mask as disclosed in Patent Document 1, photoresist patterns having different film thicknesses can be formed by a single exposure, and the number of lithography processes in the flat panel display manufacturing process can be reduced. In addition, manufacturing costs can be reduced.
For example, in a liquid crystal display device using a thin film transistor (TFT), a lithography process is performed by forming photoresist patterns having different film thicknesses in a single exposure process in the channel region and source / drain electrode formation region of the TFT. As a technique, the manufacturing cost is thereby reduced.

  On the other hand, in order to improve the image quality of flat panel displays, there is an increasing demand for finer wiring patterns. When a projection exposure machine tries to expose a pattern close to the resolution limit, a phase shifter for inverting the phase is provided at the edge of the light shielding area as disclosed in Patent Document 2 in order to secure an exposure margin. A phase shift mask has been proposed.

JP2011-227391 JP2011-13283A

  Although the halftone mask can contribute to the reduction of the lithography process, the change in the intensity distribution of the exposure light at the boundary between the semi-transmissive film and the light-shielding film is relatively gradual, so that exposure is performed using the half-tone mask. The photoresist film has a problem that the cross-sectional shape at the portion corresponding to the boundary shows a gentle inclination, the process margin is lowered, and it is difficult to form a fine pattern.

  By using the phase shift mask, the resolution is improved and the pattern can be further miniaturized. However, since the phase shift mask is a technique for a binary mask, it is impossible to reduce the lithography process like a halftone mask. Therefore, when used for manufacturing a flat panel display, it cannot contribute to the reduction of the lithography process.

  Thus, with the conventional photomask, it has been impossible to achieve both a reduction in flat panel display manufacturing cost and a resolution problem.

  In view of the above problems, an object of the present invention is to provide a photomask, a photomask blank used for manufacturing the photomask, and a method for manufacturing the photomask that can achieve both reduction of the lithography process and further miniaturization of the pattern. And

The photomask according to the present invention is
Having a transflective part, a phase shift part, a boundary part and a translucent part on a transparent substrate;
The translucent part consists of a portion where the transparent substrate is exposed,
The semi-transmissive portion is formed of a semi-transmissive film provided on the transparent substrate,
The phase shift part is formed of a phase shift film provided on the transparent substrate,
The boundary portion is formed in a region where the semi-transmissive portion and the phase shift portion are adjacent to each other,
The width of the boundary is not more than a certain width;
The boundary portion is formed of a laminated structure film in which the phase shift film, the etching stopper film, and the semi-transmissive film are formed in this order.

In addition, the photomask according to the present invention is
A transparent substrate has a semi-transmissive part, a phase shift part, a boundary part, and a translucent part,
The translucent part consists of a portion where the transparent substrate is exposed,
The semi-transmissive part is formed of a semi-permeable film provided on the transparent substrate,
The phase shift part is formed of a phase shift film provided on the transparent substrate,
The boundary portion is formed in a region where the semi-transmissive portion and the phase shift portion are adjacent to each other,
The width of the boundary is not more than a certain width;
The boundary portion is formed of a laminated structure film in which the semi-transmissive film, the etching stopper film, and the phase shift film are formed in this order.

The photomask according to the present invention is
The phase shift film has a transmittance of 1 to 10% for exposure light, and the phase of the exposure light is inverted.

The photomask according to the present invention is
The transmissivity of the semi-transmissive film with respect to exposure light is 10 to 60%.

  With such a configuration, the transflective portion has a light transmittance intermediate between the phase shift portion and the translucent portion, and a multi-tone photomask is obtained by the transflective portion, the phase shift portion, and the translucent portion. be able to. Furthermore, by making the semi-transmission part and the phase shift part adjacent to each other, the profile of the exposure light at the boundary between the semi-transmission part and the phase shift part can be changed sharply, improving the shape of the exposed photoresist. In addition, pattern miniaturization can be realized. As a result, a photomask having both a halftone effect and a phase shift effect can be obtained.

The photomask according to the present invention is
The phase shift film and the semi-transmissive film can be etched with the same etching solution, and the etching stopper film has an etching selectivity with respect to the etching solution.

  With such a configuration, the photomask can be easily manufactured using wet etching in the photomask manufacturing process.

The photomask according to the present invention is
The width of the boundary portion is set to an alignment error of a photomask drawing apparatus and is equal to or less than a resolution limit of a projection exposure apparatus in which the photomask is used.

  With such a configuration, the semi-transmissive portion and the phase shift portion can be adjacent to each other without the etching stopper film at the boundary portion having an adverse effect on the exposure of the photoresist.

The photomask blanks according to the present invention are
A phase shift film and an etching stopper film are laminated on the transparent substrate in this order.

  By using the photomask blank having such a configuration, a multi-tone mask can be formed on the photomask blank by forming a transflective film according to customer specifications and applications. As a result, it is possible to shorten the manufacturing period of a photomask having desired characteristics having both a halftone effect and a phase shift effect.

A photomask manufacturing method according to the present invention includes:
A step of laminating a phase shift film and an etching stopper film in this order on a transparent substrate;
Forming a first photoresist film;
Patterning the first photoresist film;
Etching the etching stopper film using the first photoresist film as a mask;
Etching the phase shift film using the etching stopper film as a mask;
Removing the first photoresist film;
Forming a semipermeable membrane;
Forming a second photoresist film;
Patterning the second photoresist film;
Etching the semi-transmissive film using the second photoresist film as a mask;
Removing the second photoresist film;
Etching the etching stopper film using the semi-transmissive film as a mask.

In addition, the photomask manufacturing method according to the present invention includes:
A step of laminating a semi-transmissive film and an etching stopper film in this order on a transparent substrate;
Forming a third photoresist film;
Patterning the third photoresist film;
Etching the etching stopper film using the third photoresist film as a mask;
Etching the semi-transmissive film using the etching stopper film as a mask;
Removing the third photoresist film;
Forming a phase shift film;
Forming a fourth photoresist film;
Patterning the fourth photoresist film;
Etching the phase shift film using the fourth photoresist film as a mask;
Removing the fourth photoresist film;
Etching the etching stopper film using the phase shift film as a mask.

  Such a photomask manufacturing method enables patterning of the semi-transmissive film and the phase shift film. Further, it is possible to arrange the semi-transmissive film pattern and the phase shift film pattern adjacent to each other. As a result, a photomask having both a halftone effect and a phase shift effect can be manufactured.

  According to the present invention, a multi-tone halftone mask capable of further miniaturizing a pattern and reducing the number of lithography processes can be realized. As a result, for example, it is possible to contribute to a reduction in manufacturing cost of a high-quality flat panel display.

Sectional drawing which shows the main processes of the photomask by the 1st Embodiment of this invention. Sectional drawing which shows the main processes of the photomask by the 1st Embodiment of this invention. Sectional drawing which shows the main processes of the photomask by the 1st Embodiment of this invention. FIG. 5 is a comparative view of the inclination angle at the boundary between the photomask according to the first embodiment of the present invention and the photoresist film exposed by the conventional photomask. Sectional drawing which shows the main processes of the photomask by the 2nd Embodiment of this invention. Sectional drawing which shows the main processes of the photomask by the 2nd Embodiment of this invention. Sectional drawing which shows the main processes of the photomask by the 2nd Embodiment of this invention.

    Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, none of the following embodiments gives a limited interpretation in the recognition of the gist of the present invention. The same or similar members are denoted by the same reference numerals, and the description thereof may be omitted.

(Embodiment 1)
Hereinafter, the manufacturing process of Embodiment 1 of the halftone mask according to the present invention will be described in detail.

  As shown in FIG. 1A, a phase shift film 12 is formed on a transparent substrate 11 such as synthetic quartz glass by a sputtering method or the like, and an etching stopper film 13 is formed thereon by a sputtering method or the like. Thus, a photomask blank 10 is prepared.

The phase shift film 12 has a phase shift angle of approximately 180 degrees, and the phase of the exposure light is reversed. The light transmittance of the phase shift film 12 with respect to the exposure light is 1% to 10%.
If the light transmittance of the phase shift film 12 is too low, the effect of phase shift is reduced, so that the typical light transmittance is 5 to 7%. Specifically, for example, a Cr (chromium) oxide film, a Cr oxynitride film or the like having a film thickness of 80 to 200 [nm] is used, and the film thickness and composition are adjusted in accordance with necessary characteristics. Further, it is not necessarily a single layer film, and for example, a film in which the composition changes in the film thickness direction or a film in which films having different compositions are stacked may be used.
As exposure light, g-line, h-line, i-line or a mixture of two or more of these can be used.
Here, approximately 180 [degrees] is specifically in the range of 180 ± 10 [degrees], and if it is within this range, the effect of phase inversion can be sufficiently obtained.

  The etching stopper film 13 is made of a material different from the phase shift film 12 and having different etching characteristics. Specifically, as the etching stopper film 13, for example, a Ti (titanium) -based film (Ti, Ti oxide film, Ti oxynitride film, or a laminated film thereof) having a film thickness of 4 to 30 [nm], Ni (nickel) A system film (Ni, Ni oxide film, Ni oxynitride film, or a laminated film thereof), a MoSi (molybdenum silicide) film, or the like is used.

  Next, a first photoresist film 14 is formed on the etching stopper film 13 by a coating method.

  Next, as shown in FIG. 1B, the first photoresist film 14 is exposed by, for example, a photomask drawing apparatus and then developed to form first photoresist patterns 14a, 14b, and 14c. .

Next, as shown in FIG. 1C, the etching stopper film 13 is etched using the first photoresist patterns 14a, 14b, and 14c as masks to form etching stopper film patterns 13a, 13b, and 13c.
Etching can be performed by wet etching or dry etching. When the etching stopper film 13 is selectively etched with respect to the phase shift film 12, it is preferable to use wet etching having a high selection ratio. The etchant has selectivity with respect to the phase shift film 12 (has etching resistance), and a chemical solution that can etch the etch stopper film 13 may be selected in accordance with the material of the etch stopper film 13. For example, in the case of using a Ti-based film, a mixed solution of potassium hydroxide (KOH) and hydrogen peroxide water can be preferably used, but is not limited thereto.

Next, as shown in FIG. 2A, the first photoresist patterns 14a, 14b, and 14c are removed by ashing or the like, and then the phase shift film 12 is formed using the etching stopper film patterns 13a, 13b, and 13c as a mask. Etching is performed to form phase shift film patterns 12a, 12b, and 12c.
As an etching method for the phase shift film 12, a wet etching method or a dry etching method is used. However, since the phase shift film 12 is selectively etched with respect to the etching stopper film, a wet etching method capable of obtaining a high etching selectivity can be suitably used.
For example, when the etching stopper film 13 is a Ti-based film and the phase shift film 12 is a Cr oxide film and a Cr oxynitride film as described above, a cerium-based etchant, for example, nitric acid first solution is used as the phase shift film 12 etchant An aqueous solution of dicerium ammonium can be preferably used, but is not limited thereto.

Alternatively, after the phase shift film 12 is etched to form the phase shift film patterns 12a, 12b, and 12c, the first photoresist pattern 14a may be removed by an ashing method or the like.
In this case, the etching process of the etching stopper film 13 and the etching process of the phase shift film 12 can be performed continuously.

Next, as shown in FIG. 2B, for example, a semi-transmissive film 15 such as Cr, Cr oxide film, Cr oxynitride film having a film thickness of 1 to 40 [nm] is formed as a halftone film by sputtering or the like. After that, a second photoresist film 16 is formed on the semi-transmissive film 15 by a coating method.
Here, the light transmittance of the semi-transmissive film 15 is set to 10 to 60%, typically 20% to 55%. The semi-transmissive film 15 does not reverse the phase of the exposure light, and the phase shift angle is, for example, 0.4 to 15 degrees. The optical characteristics of the semi-transmissive film can be adjusted by the film thickness and composition.

  Here, the light transmittance of the semi-transmissive film, which is a halftone film, is determined by the purpose of use, customer specifications, and the like. Therefore, by preparing a photomask blank in which a phase shift film and an etching stopper film are laminated in advance and forming a halftone film according to the customer's specifications, manufacturing from photomask specification determination to photomask completion The construction period can be shortened.

  Next, as shown in FIG. 2C, the second photoresist film 16 is exposed and developed to form a second photoresist pattern 16a.

Next, as shown in FIG. 2D, the semi-transmissive film 15 is etched using the second photoresist pattern 16a as a mask to form a semi-transmissive film pattern 15a, and then the second photo pattern is formed by ashing or the like. The resist pattern 16a is removed.
A wet etching method or a dry etching method can be used as an etching method for the semi-transmissive film 15, but a wet etching method capable of obtaining a high etching selectivity can be preferably used.
When a Cr film is used as the semi-transmissive film 15 similarly to the phase shift film 12, for example, an aqueous solution of ceric ammonium nitrate can be used as an etching solution.

Next, as shown in FIG. 3, the etching stopper film patterns 13a, 13b, and 13c on the phase shift film patterns 12a, 12b, and 12c are etched using the semi-transmissive film pattern 15a as a mask. A part of the etching stopper film patterns 13d and 13e remain below the semi-transmissive film pattern 15a.
As the etching method, a wet etching method or a dry etching method can be used, but a wet etching method that can obtain a high etching selectivity can be preferably used. As described above, a mixed solution of KOH and hydrogen peroxide water can be suitably used as the etching solution.

  2C, the semi-transmissive film 15 is etched using the second photoresist pattern 16a as a mask to form a semi-transmissive film pattern 15a, and an etching stopper on the phase shift film pattern 12a. After etching the film pattern 13a, the second photoresist pattern 16a may be removed by ashing or the like.

  As shown in FIG. 3, phase shift film patterns 12a, 12b and 12c and a semi-transmissive film pattern 15a are formed on the photomask, and the transparent substrate 11 is exposed in the other regions.

  In FIG. 3, the phase difference between the phase shift portion formed by the phase shift film patterns 12b and 12c and the semi-transmission portion formed by the semi-transmission film pattern 15a is approximately 180 [degrees]. The phase difference between the phase shift part in the part and the semi-transmission part formed by the pattern 15a of the semi-transmission part is 180-α when the phase shift angle of the semi-transmission film is α [degrees]. For example, when the transmittance is 54%, α = 1.1 [degrees] is extremely small, and the phase difference can be regarded as approximately 180 [degrees]. Alternatively, if necessary, the phase difference can be easily kept within a range of 180 ± 10 [degrees] by fine adjustment of the thickness of the phase shift film 12 or the like. For this reason, the exposure light distribution also changes steeply at these boundary portions, and as a result, the profile of a photoresist formed on, for example, a flat panel substrate using the present photomask changes sharply at the boundary portions.

In addition, since the phase shift angle between the transparent portion where the substrate is exposed and the phase shift portion formed of the phase shift film is approximately 180 degrees, the profile of the photoresist formed by exposure is also steep at these boundaries. Become.
As a result, it is possible to realize a photomask that can achieve both a halftone effect and a phase shift effect.

  As described above, the etching stopper film patterns 13d and 13e remain at the boundary between the phase shift portion and the semi-transmissive portion. The width of the etching stopper film patterns 13d and 13e remaining at the boundary portion is an amount corresponding to an alignment error (alignment deviation) of a photomask drawing apparatus (laser drawing apparatus) for exposing the second photoresist pattern 16a. It is. As a result, the semi-transmissive portion and the phase shift portion are overlapped and can be adjacent to each other without generating a gap.

The widths of the etching stopper film patterns 13d and 13e are set to dimensions that do not affect the exposure result when the photoresist is exposed by the photomask pattern. That is, the widths of the etching stopper film patterns 13d and 13e are set to be equal to or less than the resolution limit of a projection exposure apparatus that exposes the photoresist using a photomask.
As a rule of thumb, the value of the resolution limit of the projection exposure apparatus is expressed by
Can be used. Here, λ is the wavelength (representative wavelength) of the projection exposure apparatus, and NA is the numerical aperture of the projection exposure apparatus. By setting the width of the etching stopper film patterns 13d and 13e to be equal to or less than the resolution limit, the exposure result of the photoresist is not affected.

Specifically, the actual widths of 13d and 13e in the produced photomask are set by setting the widths (set values) of the boundary portions 13d and 13e as the alignment error d [μm] of the photomask drawing apparatus. The (actual measured value) falls within the range of 0 to 2d. A typical value of d of the laser drawing apparatus is, for example, 0.5 [μm], and the actual width of the boundary portion in the photomask is 0 to 1 [μm].
Further, in the currently widely used projection exposure apparatus for flat panel displays, the NA is about 0.09 and the representative wavelength λ is 365 [nm]. When these values are applied to the above equation, the resolution limit value is 2.0 [μm]. Compared with the value of the resolution limit, the alignment error of the laser drawing apparatus is sufficiently small. Therefore, by setting the widths of the etching stopper film patterns 13d and 13e to the alignment error of the photomask drawing apparatus, the actual conditions will be less than the resolution limit of the photoresist projection exposure apparatus. It is possible to achieve both.

  For the photomask of this embodiment, for example, the phase shift film patterns 12b and 12c can be used for TFT source / drain electrodes, and the semi-transmissive film pattern 15a can be used for patterning the TFT channel region. Since the profile of the photoresist film at the boundary between the source / drain region and the channel region becomes steep, and the edge portion of the source / drain electrode also becomes steep, miniaturization of the TFT can be realized.

  FIG. 4 shows a photo exposed by a conventional photomask in which the shape of the photoresist exposed by this embodiment combining a halftone film and a phase shift film and a halftone film and a light-shielding film that does not transmit exposure light are combined. A comparison with the resist shape is shown.

  4A is a cross-sectional view of the photomask of this embodiment, and FIG. 4A is an enlarged view of a part of FIG. FIG. 4B is a part of a cross section of a conventional photomask disclosed in Patent Document 1, in which a halftone film pattern 43 is formed on a transparent substrate 42, and a barrier is formed on the halftone film pattern 43. A film (etching stopper film) pattern 44 and a light shielding film pattern 45 are formed.

FIG. 4C schematically shows a cross-sectional shape of the photoresist 30 exposed by the photomask shown in FIG. The photoresist film thickness at the portion corresponding to the semi-transmissive film, which is a halftone film, is thinner than the photoresist film thickness at the position corresponding to the phase shift film, and different photoresist film thicknesses by one exposure with one photomask. A region having can be formed.
In FIG. 4C, a point P indicated by a black circle indicates a portion corresponding to the boundary between the semi-transmissive film that is a halftone film and the phase shift film.

  Similarly, using a conventional photomask, a photoresist 40 having different film thicknesses can be formed by one exposure, and FIG. 4D is exposed by the photomask shown in FIG. The cross-sectional shape of the photoresist 40 is schematically shown. A point Q indicated by a black circle in FIG. 4D indicates a portion corresponding to the boundary between the halftone film and the light shielding film.

FIG. 4E is a graph showing the inclination angles of the photoresists 30 and 40 at points P and Q in comparison. As apparent from FIG. 4E, the inclination angle of the point P of the photomask according to the present embodiment is larger than the inclination angle of the point Q of the conventional photomask, and the cross-sectional shape of the boundary portion of the photoresist 30 is larger. It can be understood that it becomes steep.
That is, in comparison with the case where the photoresist is exposed by the conventional photomask, the photoresist film is improved by exposing the photoresist by the photomask according to the present embodiment, and in the boundary region where the resist film thickness changes. A steep cross-sectional shape can be obtained.

(Embodiment 2)
In Embodiment 1 above, the semi-transmissive film is formed after the phase shift film is formed on the transparent substrate. However, the photomask is manufactured by forming the semi-transmissive film on the transparent substrate and then forming the phase shift film. May be.
Hereinafter, a photomask manufacturing method will be described with reference to the drawings. However, as the transparent substrate, the phase shift film, the semi-transmissive film, and the etching stopper film, films similar to those in Embodiment 1 can be used.

  As shown in FIG. 5A, a semi-transmissive film 22 is formed as a halftone film on a transparent substrate 21 such as synthetic quartz glass by a sputtering method or the like, and an etching stopper film 23 is formed thereon by a sputtering method or the like. The photomask blanks 20 are prepared by forming a film by the above.

  Next, a third photoresist film 24 is formed on the etching stopper film 23 by a coating method.

  Next, as shown in FIG. 5B, the third photoresist film 24 is exposed and developed to form a third photoresist pattern 24a.

  Next, as shown in FIG. 5C, the etching stopper film 23 is etched using the third photoresist pattern 24a as a mask to form an etching stopper film pattern 23a.

    Next, as shown in FIG. 6A, the third photoresist pattern 24a is removed by ashing or the like, and then the semi-transmissive film 22 is etched using the pattern 23a of the etching stopper film as a mask. 22a is formed.

Further, after the step of FIG. 5C, the semi-transmissive film 22 may be etched to form the semi-transmissive film pattern 22a, and then the third photoresist pattern 24a may be removed by an ashing method or the like. In this case, the etching step of the etching stopper film 23 and the etching step of the semi-transmissive film 22 can be performed continuously, and a high etching selectivity with respect to the semi-transmissive film 22 is not necessarily ensured in the etching step of the etching stopper film 23. There is no need.
However, as in the step of FIG. 2A, etching the semi-transmissive film 22 using the pattern 23a of the etching stopper film as a mask is effective in suppressing side etching of both films.

  Next, as shown in FIG. 6B, a phase shift film 25 is formed by a sputtering method or the like, and then a fourth photoresist film 26 is formed on the phase shift film 25 by a coating method.

  Next, as shown in FIG. 6C, the fourth photoresist film 26 is exposed and developed to form fourth photoresist patterns 26a, 26b, and 26c.

  Next, as shown in FIG. 6D, the phase shift film 25 is etched using the fourth photoresist patterns 26a, 26b, and 26c as masks to form phase shift film patterns 25a, 25b, and 25c. Thereafter, the fourth photoresist patterns 26a, 26b, and 26c are removed by ashing or the like.

  Next, as shown in FIG. 7, the pattern 23a of the etching stopper film on the pattern 22a of the semi-transmissive film is etched using the patterns 25a and 25b of the phase shift film as a mask.

  6C, the phase shift film 25 is etched using the fourth photoresist pattern 26a as a mask to form phase shift film patterns 25a, 25b, and 25c, and a semi-transmissive film pattern 22a. After the etching stopper film pattern 23a is etched, the fourth photoresist pattern 26a may be removed by ashing or the like.

In FIG. 7, the phase difference between the phase shift part formed by the phase shift film patterns 25a and 25b and the semi-transmission part of the semi-transmission film pattern 22a is 180 when the phase shift angle of the semi-transmission film is α [degrees]. -Α, but when the transmissivity of the semi-permeable membrane is high, for example, if the transmissivity is 54%, α = 1.1 degrees is extremely small, and the phase difference can be regarded as approximately 180 [degrees]. Alternatively, if necessary, the phase difference can be easily kept within a range of 180 ± 10 [degrees] by fine adjustment of the thickness of the phase shift film 12 or the like. For this reason, the exposure light distribution changes steeply even in this boundary portion, and as a result, the profile of a photoresist formed on, for example, a flat panel substrate using this photomask changes sharply in the corresponding boundary portion.
In addition, since the phase difference between the phase shift portion and the transparent portion where the substrate is exposed is also approximately 180 degrees, the exposure light distribution at the boundary portion changes abruptly, and a photoresist formed using this photomask. The profile can be a steep shape at the corresponding boundary portion.

  INDUSTRIAL APPLICABILITY The present invention can provide a photomask capable of realizing a reduction in photolithography processes and pattern miniaturization, and the industrial applicability is extremely large.

DESCRIPTION OF SYMBOLS 10 Photomask blank 11 Transparent substrate 12 Phase shift film 12a, 12b, 12c Phase shift film pattern 13 Etching stopper film 13a, 13b, 13c, 13d, 13e Etching stopper film pattern 14 First photoresist film 14a, 14b, 14c First photoresist pattern 15 Semi-transmissive film 15a Semi-transmissive film pattern 16 Second photoresist film 16a Second photoresist pattern 20 Photomask blanks 21 Transparent substrate 22 Semi-transmissive film 22a Semi-transmissive film pattern 23 Etching Stopper film 23a Etching stopper film pattern 24 Third photoresist film 25 Phase shift film 25a, 25b, 25c Phase shift film pattern 26 Fourth photoresist film 26a, 26b, 26c Fourth photoresist Pattern of turns 30 photoresist 40 photoresist 42 transparent substrate 43 pattern 45 light-shielding film pattern 44 barrier film of the halftone film

Claims (9)

Having a transflective part, a phase shift part, a boundary part and a translucent part on a transparent substrate;
The translucent part consists of a portion where the transparent substrate is exposed,
The semi-transmissive portion is formed of a semi-transmissive film provided on the transparent substrate,
The phase shift part is formed of a phase shift film provided on the transparent substrate,
The boundary portion is formed in a region where the semi-transmissive portion and the phase shift portion are adjacent to each other,
The width of the boundary is not more than a certain width;
The boundary portion, the phase shift film, the etching stopper Pas film, the one that the semi-permeable membrane Ru is formed in a laminated structure film formed in this order, the semi-transmission portion excluding the boundary portion, the phase sheet
The etching stopper film of the bottom part and the light transmitting part is removed,
A width of the boundary portion is less than a resolution limit of a projection exposure apparatus in which the photomask is used . A transparent substrate has a semi-transmissive part, a phase shift part, a boundary part, and a translucent part,
The translucent part consists of a portion where the transparent substrate is exposed,
The semi-transmissive part is formed of a semi-permeable film provided on the transparent substrate,
The phase shift part is formed of a phase shift film provided on the transparent substrate,
The boundary portion is formed in a region where the semi-transmissive portion and the phase shift portion are adjacent to each other,
The width of the boundary is not more than a certain width;
The boundary portion, the semi-transparent film, the etching stopper Pas film, whereas the phase shift film is Ru are formed in this order, the semi-transmission portion excluding the boundary portion, the etching stopper of said phase shift portion and said light transmission portion The membrane is removed,
A width of the boundary portion is less than a resolution limit of a projection exposure apparatus in which the photomask is used . 3. The photomask according to claim 1, wherein the phase shift film has a transmittance of 1 to 10% for exposure light, and the phase of the exposure light is inverted. 4. The photomask according to claim 1, wherein the transflective film has a transmittance of 10 to 60% for exposure light. The phase shift film and the semi-transmissive film can be etched with the same etchant,
The photomask according to claim 1, wherein the etching stopper film has etching selectivity with respect to the etching solution. The etching stopper film is composed of a Ti-based film, and the phase shift film is composed of a Cr oxide film.
The photomask according to claim 5 . A photomask blank for producing the photomask according to claim 1,
Photomask blank in which the phase shift film and the etching stopper layer on the transparent substrate, characterized in that are laminated in this order. A step of laminating a phase shift film and an etching stopper film in this order on a transparent substrate;
Forming a first photoresist film;
Patterning the first photoresist film;
Etching the etching stopper film using the first photoresist film as a mask;
Etching the phase shift film using the etching stopper film as a mask;
Removing the first photoresist film;
Forming a semipermeable membrane;
Forming a second photoresist film;
Patterning the second photoresist film so as to have an overlap of the etched stopper film and the width below the resolution limit of the projection exposure apparatus ;
Etching the semi-transmissive film using the second photoresist film as a mask;
Removing the second photoresist film;
2. The method of claim 1 , further comprising: etching the etching stopper film on the phase shift film using the semi-transmissive film as a mask, and removing the etching stopper film excluding the boundary portion . Production method. A step of laminating a semi-transmissive film and an etching stopper film in this order on a transparent substrate;
Forming a third photoresist film;
Patterning the third photoresist film;
Etching the etching stopper film using the third photoresist film as a mask;
Etching the semi-transmissive film using the etching stopper film as a mask;
Removing the third photoresist film;
Forming a phase shift film;
Forming a fourth photoresist film;
Patterning the fourth photoresist film so as to have an overlap of the etched stopper film and the width below the resolution limit of the projection exposure apparatus ;
Etching the phase shift film using the fourth photoresist film as a mask;
Removing the fourth photoresist film;
3. The photomask according to claim 2 , further comprising: etching the etching stopper film on the semi-transmissive film using the phase shift film as a mask, and removing the etching stopper film excluding the boundary portion . Production method.

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