JP2018005072A - Halftone mask and halftone mask blank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that since in a conventional multi-gradation halftone mask, a pinhole defect formed in a semi-transmitting film is detected by a defect detection device and corrected, it is difficult to repair a fine pinhole defect such as a defect equal to or smaller than a detection limit.SOLUTION: A halftone mask is provided, in which a semi-transmitting film of the halftone mask is configured to have a phase difference of 60 to 90 degrees with respect to a transparent substrate and a transmittance of 20 to 50%. Thereby, the halftone mask prevents exposure of a photoresist as a transfer target through a pinhole in a specific size or smaller in the semi-transmitting film and reduces the risk of generating a pattern defect in a product.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a multi-tone halftone mask and a halftone mask blank used for a flat panel display or the like.

In a technical field such as a flat panel display, a semi-transparent film is not a phase shifter, and a multi-tone photo called a half-tone mask (or gray-tone mask) having a function of limiting an exposure amount by its transmittance. A mask is being used. By using a halftone mask, photoresist patterns with different film thicknesses can be formed by a single exposure, reducing the number of lithography steps in the manufacturing process of flat panel displays and reducing manufacturing costs. It becomes possible.
Such a semi-transmissive film has a function that is completely different from a “phase shifter” that is substantially used for a binary mask, with the semi-transmissive film serving as an auxiliary pattern for the pattern of the light-shielding film for the purpose of improving the resolution of the fine pattern.

  The halftone mask for such applications uses a semi-transmissive film having an intermediate transmittance between the transparent substrate and the light-shielding film, and can realize, for example, three gradations by using the transparent substrate, the semi-transmissive film, and the light-shielding film. it can. It is also possible to realize a halftone mask having four or more gradations using a plurality of transflective films.

  In general, in the photomask manufacturing process, if an accidental defect such as a pinhole occurs due to, for example, a foreign substance during film formation or a developer mist during pattern formation of the photomask, the defect is caused by lithography using the photomask. In the process, it is exposed to a photoresist which is a transfer target. Therefore, the photomask is inspected for defects after completion, and repaired if necessary.

In the case of a halftone mask, if a pinhole defect in a semi-transmissive film is detected in the defect inspection process, the defect is repaired by forming a carbon film in the pinhole portion using an FIB apparatus (focused ion beam apparatus). Techniques for doing this are well known.
Patent Document 1 discloses a technique for recognizing the coordinates of a pinhole defect with a defect inspection apparatus and forming carbon in the pinhole portion using an FIB apparatus.

JP 2008-256759 A

As the image quality of flat panel displays increases, the miniaturization of patterns advances, and countermeasures against exposure failures due to minute pinholes become increasingly important.
However, it is generally difficult to detect a defect of a halftone mask as compared with a binary mask. In other words, the defect inspection optically detects a defect, and the light shielding film can detect the defect by the light contrast. However, since the semi-transmissive film has light transmission, Thus, it is difficult to detect a “white defect” in which a part of the semipermeable membrane is missing.

  Therefore, if minute pinholes (white defects) that have not been detected by the defect inspection apparatus remain, the photoresist is exposed with a halftone mask. As a result, the photoresist is exposed at the pinhole portion, and the photoresist film thickness is locally increased. Therefore, there is a risk of finishing thinner than a desired film thickness.

Reference 1 discloses a repair technique in which a carbon film matching the transmittance of the semi-permeable film is formed in the pinhole portion by using an FIB apparatus. However, the repair process is complicated, and repair is difficult when the defect size is small. There is a problem of being.
In addition, the repair technique for forming the carbon film by the FIB apparatus repairs defects detected by the defect inspection apparatus, and therefore cannot repair defects below the sensitivity limit of the defect inspection apparatus. As for the white defect of the film, there is a problem that it is difficult to detect a fine defect itself. Therefore, it is necessary to inspect again for the presence or absence of defects in the photoresist exposed by the halftone mask.

  In view of the above-described problems, the present invention provides a halftone mask capable of preventing exposure failure of a photoresist film due to pinholes (white defects) of a fine semi-transmissive film that is smaller than a specific size, for example, difficult to detect, and A halftone mask blank for manufacturing the same is provided.

The halftone mask according to the present invention is
On the transparent substrate, with a light shielding film pattern and a semi-transmissive film pattern,
The semi-transmissive film has a transmittance of 20 to 50% and a phase difference of 60 to 90 degrees with respect to the transparent substrate.

  Further, the transmissivity of the semi-transmissive film with respect to the transparent substrate is 30%, and the phase difference is 80 to 90 degrees.

  By giving a specific phase difference to the transflective film in the halftone mask, the interference effect at the boundary of a specific width between the transparent area and the transflective film area causes a specific size or less on the transflective film of the halftone mask. This pinhole does not resolve to the photoresist, or it is possible to cause only a variation that the photoresist film thickness falls within the allowable range of the exposure margin.

  The light shielding film is a chromium film, and the semi-transmissive film is a chromium oxide film, a nitride film, or an oxynitride film.

  By controlling and adjusting the composition and thickness of the chromium oxide film, nitride film, or oxynitride film, a pattern of a semi-transmissive film having a desired transmittance and phase difference can be formed on the halftone mask.

The halftone mask blank according to the present invention comprises a transflective film and a light shielding film on a transparent substrate,
The semi-transmissive film has a transmittance of 20 to 50% and a phase difference of 60 to 90 degrees with respect to the transparent substrate.

  The transflective film has a transmittance of 30% and a phase difference of 80 to 90 degrees with respect to the transparent substrate.

  By using such halftone mask blanks, selecting a semi-transmissive film according to the specifications and manufacturing a half-tone mask, it is possible to avoid resolving fine pinholes below a specific size of the semi-transmissive film. A tone mask can be manufactured at low cost.

The halftone mask according to the present invention is
The size of the semi-permeable membrane pattern is reduced by a predetermined correction amount with respect to a design value.

  By using such a semi-transmissive film pattern, it is possible to eliminate a defect in the photoresist due to a fine pinhole having a specific size or less, and to form a photoresist pattern as designed.

According to the present invention, halftone mask blanks and halftone masks that can prevent pattern abnormalities due to transfer even for pinholes of a specific size or less, especially for pinholes that have been difficult to repair in the past, are below detection limits. It can be provided at low cost.
As a result, it is possible to provide a halftone mask capable of reducing the risk of product pattern defects in a lithography process using the halftone mask according to the present invention.

Sectional drawing of a halftone mask of 3 gradations. Phase difference dependence of exposure light intensity at the pinhole. Pinhole diameter dependence of photoresist surface shape. Phase difference dependence of photoresist cross-sectional shape. Phase dependence of exposure light intensity and photoresist film thickness distribution using a halftone mask. Phase difference dependence of photoresist film thickness distribution near the boundary between transparent substrate and translucent film. The top view which shows the dimension correction | amendment of the semi-permeable membrane of a halftone mask. The transmittance and NA dependence of the dimensional correction amount of the semipermeable membrane.

(Principle of problem solving)
According to the halftone mask of the present invention, a pinhole having a specific size or less is set by setting a phase difference with a transparent substrate in a specific region for a semi-transmissive film having a predetermined transmittance with respect to exposure light. However, it is possible to prevent the occurrence of defects due to pinholes in the photoresist without repairing the pinholes in the semi-transmissive film.

  That is, due to the interference effect of the exposure light between the transparent area and the semi-transmissive film area, the exposure light transmission intensity near the boundary between the transparent area and the semi-transmissive area is reduced, and thereby the lower resolution limit for the hole shape of the semi-transmissive film By setting the value above the specific pinhole size of interest, pinholes below the specific pinhole size are resolved on the photoresist and the photoresist opens (thickness is zero or below the allowable lower limit) ).

On the other hand, in the region near the pinhole, particularly in the semi-transmissive film region surrounding the pinhole, the resist film thickness may be increased due to a decrease in exposure light intensity.
Therefore, the transmittance of the semi-transmissive film is semi-transmissive so that the thickness of the photoresist corresponding to the vicinity of the pin hole of the semi-transmissive film is within an allowable range with respect to the photoresist patterned by the lithography process. By setting the phase shift range of the film to an optimum range, countermeasures against pinhole defects in the semi-transmissive film are taken.

  Therefore, the conventional method for detecting pinholes in a semi-transmissive film of a photomask and detecting the pinholes is used to prevent the occurrence of photoresist defects.

Thus, since the problem-solving method of the present invention is to prevent defects in the photoresist by adjusting the resolution in the vicinity of the pinhole, the optimum range of the phase shift of the semi-transmissive film is the target. It also depends on the pinhole size of the semipermeable membrane.
As an example, the transmittance of the semi-transmissive film is determined by the required film thickness of the photoresist, and the transmittance of the semi-transmissive film of the halftone mask is normally set to a value of about 30%. Therefore, the case where the transmittance is 30% will be described in detail below as an example.
In addition, as the pinhole size, we focused on the size corresponding to the lower limit value of the conventional defect inspection apparatus, and as a result, compared with the pinhole of the semi-permeable membrane that could not be repaired in principle by the conventional technology. However, it will be explained that the defect of the photoresist due to the pinhole can be avoided.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. However, each embodiment and each example do not give 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.

  FIG. 1 shows a cross-sectional shape of a three-tone halftone mask. A pattern of the light-shielding film 2 made of, for example, a chromium film and a pattern of the semi-transmissive film 3 made of, for example, chromium oxide are formed on the transparent substrate 1 by a known manufacturing technique.

For example, the manufacturing process of the halftone mask of three gradations is as follows.
(1) First, a photomask blank in which the light shielding film 2 is covered on almost the entire surface of the transparent substrate 1 is prepared, a first resist pattern is formed on the light shielding film 2, and the exposed light shielding is performed using this as a mask. A light shielding pattern is formed by etching the film 2.
(2) Next, after removing the remaining first resist pattern, a semi-transmissive film 3 covering the transparent substrate 1 and the light shielding film 2 is formed.
(3) Next, a second resist pattern is formed on the semi-transmissive film 3 and the exposed semi-transmissive film 3 is etched using the second resist pattern as a mask to form a semi-transmissive pattern.

  Alternatively, a half-tone mask may be formed by forming the semi-transmissive film 3 and the light-shielding film 2 in this order on the transparent substrate 1 and etching using the resist pattern in the order of the light-shielding film 2 and the semi-transmissive film 3. Alternatively, an etching stopper film may be inserted between the semi-transmissive film and the light shielding film, and at least the same kind of film material may be used. Further, the light shielding film is not limited to a single layer, and may be any structure as long as the optical density satisfies 3.0 or more.

FIG. 2 shows the phase difference dependence of the intensity of exposure light (transmitted light) transmitted through a pinhole (white defect) diameter of 0.5 to 2 μm in the semi-transmissive film 3 when the transmittance of the semi-transmissive film 3 is 30%. Shown in In the figure, symbols ◇, □, Δ, and ○ indicate exposure light intensities with pinhole diameters (defect sizes) of 2.0, 1.5, 1.0, and 0.5 μm, respectively.
The transmittance is the transmittance of the semi-transmissive film 3 when the transmittance of the transparent substrate 1 is 100% with respect to the exposure light, and the phase difference is the phase difference of the semi-transmissive film 3 with respect to the transparent substrate 1. is there. The wavelength of the exposure light is a mixed wavelength from i to g line.

  In FIG. 2, dotted lines A and B indicate the upper and lower limits of the allowable range of exposure light intensity. When the upper limit is exceeded, the photoresist is exposed and the film thickness is greatly reduced (opened), resulting in a white defect, and when below the lower limit, the exposure amount is insufficient and the photoresist film thickness increases, resulting in a black defect.

  As shown in FIG. 2, the conditions for the variation of the photoresist film thickness to be within the allowable range of the exposure margin are when the pinhole diameter is 0.5 μm, at least in the range of phase difference 30 to 120 degrees, and 1.0 μm. The phase difference is in the range of 30 to 90 degrees, in the case of 1.5 μm, the phase difference is in the range of 60 to 90 degrees, and in the case of 2.0 μm, the phase difference is in the range of 80 to 110 degrees.

For example, even if the detection sensitivity of the defect detection device is 1.5 μm and it is difficult to repair pinholes below the detection sensitivity, the phase difference of the semi-permeable membrane with respect to the permeable membrane is 60 to 90 degrees (in FIG. In this case, such pinholes do not expose the photoresist.
Alternatively, even if a pin hole of 1.5 μm is detected by the defect detection device, it does not need to be repaired because it does not become a defect in the photoresist that is a transfer target.

  Further, in order to allow a pinhole of 2.0 μm having a larger diameter with respect to the semipermeable membrane 3, the phase difference may be set to 80 to 90 degrees. Therefore, regardless of the detection sensitivity of the defect inspection apparatus, the pinhole size may be appropriately specified according to the minimum size to be repaired, and the transmittance and the phase difference may be set accordingly.

FIG. 3 shows the surface shape of the photoresist when the semi-transmissive film 3 having a transmittance of 30% and a phase difference of 30 degrees and 80 degrees is exposed with a halftone mask having pinholes of various diameters.
When the phase difference is 30 degrees, a pin hole having a diameter of 2.0 μm exposes the photoresist of the transferred object, and a hole is opened in the photoresist film. When the phase difference is 80 degrees, the photoresist of the transferred object is exposed. It can be seen that pinholes do not resolve above and prevent photoresist opening.

  FIG. 4 shows a cross-sectional shape of a portion corresponding to a pinhole portion of a photoresist exposed using a halftone mask having a 2 μm-diameter pinhole in a semi-transmissive film, and a solid line indicates a transmittance of 30% and a phase difference of 80. In the case of a semi-transparent film, the dotted line shows the cross-sectional shape of the photoresist film thickness in the case of a semi-transmissive film having a transmittance of 30% and a phase difference of 30 degrees.

  In the case of a semi-transmissive film having a phase difference of 30 degrees, an opening having a photoresist film thickness of 0 (zero) exists, but in the case of a semi-transmissive film having a phase difference of 80 degrees, there is no opening and the film thickness is sufficient. Therefore, white defects can be avoided, and the film thickness variation is within the allowable range of the exposure margin.

As described above, the larger the white defect size to be allowed, the more strictly the phase difference needs to be controlled. However, when the transmissivity of the semi-transmissive film 3 changes, the optimum phase difference value also changes.
For example, when it is desired to allow a pinhole size of up to 1.5 μm, the range of the phase difference satisfying the exposure margin for a semi-transmissive film with a transmittance of 30% is 60 to 80 degrees, but the size is larger. When it is desired to allow 0 μm, it is necessary to control the phase difference to 80 degrees. On the other hand, the semi-transparent film 3 having a transmittance of 50% is optimal when it is desired to allow a pinhole size of up to 1.5 μm, a phase difference range of 50 to 70 degrees, and a pinhole size of up to 2.0 μm. The phase difference is 60 degrees.

  Thus, when the range of the phase to be controlled and the optimum value change depending on the transmittance and the pinhole size to be allowed and the pinhole size is allowed up to 2.0 μm, the optimum phase difference is the transmittance of the semi-transmissive film. In the case of 10, 20, 30, 40, 50%, the optimum phase difference is 100, 90, 80, 70, 60 degrees. The transmissivity of the semi-permeable membrane can be selected according to the customer's request and the like, and the phase difference can be determined with respect to the transmissivity.

    As described above, by adjusting the phase difference with respect to the semi-transmissive film 3, even if a pinhole having a diameter smaller than the detection limit of the inspection apparatus exists, it is possible to prevent the occurrence of a defective film thickness of the photoresist. Can do.

Therefore, the halftone mask blanks in which the semi-transmissive film 3 having the phase difference and the transmittance of 60 to 90 degrees and the transmittance of 20 to 50% and the light-shielding film 2 are formed on the transparent substrate 1, respectively. From the above, by selecting the transmittance according to the mask specifications (or customer requirements) and manufacturing the halftone mask, it is possible to avoid the defect of the photoresist due to the fine pinhole below the detection limit.
As a result, it is possible to improve the product yield while significantly reducing the cost of the halftone mask correction process.

  Note that the transmittance and the phase difference can be controlled by the film thickness and composition of the semipermeable membrane, and by controlling each, it is possible to obtain a desired semipermeable membrane. For example, by measuring the phase difference and transmittance of a film whose thickness and composition are changed in advance and converting it into data, it is possible to form a semi-transmissive film that meets the specifications of the halftone mask.

  As such a semi-permeable film, for example, an oxide film such as chromium (Cr), titanium (Ti), nickel (Ni), molybdenum (Mo), a nitride film, an oxynitride film, and an oxycarbide film can be used. The composition and film thickness of nitrogen and carbon may be adjusted.

  These films can be formed by reactive sputtering. For example, in adjusting the composition of a chromium oxynitride film, it can be formed by sputtering using a gas in which oxygen, nitrogen, or nitrous oxide is mixed with argon as a target, and the gas mixing ratio. The composition can be controlled by changing (partial pressure). For example, in the case of a chromium oxide film, a mixed gas of argon and oxygen; in the case of a chromium nitride film, a mixed gas of argon and nitrogen; in the case of a chromium oxycarbide film, argon and oxygen; A mixed gas with carbon may be used. The same applies to other metals.

  In addition to the reactive sputtering method, a semi-transmissive film may be formed using a reactive vapor deposition method or a CVD method using an organic metal source as a raw material, and the composition may be controlled.

  Hereinafter, a mechanism for avoiding a defect in the photoresist due to pinholes in the semi-transmissive film will be described in detail.

FIG. 5 shows (a) a halftone mask having a pattern of a light-shielding film and a semi-transmissive film on a transparent substrate, and (b) exposure light intensity distribution and (c) developed after exposure when exposed using the same. The film thickness distribution of a photoresist is shown. 5B and 5C, the solid line indicates the exposure light intensity when the phase difference of the semi-transmissive film with respect to the transparent substrate is 80 degrees, and the dotted line indicates the exposure light intensity when the phase difference of the semi-transmissive film with respect to the transparent substrate is 30 degrees. And shows the film thickness distribution of the photoresist film.
The transmissivity of the semi-transmissive film is 30%, and the wavelength of the exposure light is a mixed wavelength of i-line to g-line, and NA = 0.1.

  As shown in FIG. 5B, in any case, the exposure light intensity is 0 in the light shielding film region of the halftone mask, and the exposure light intensity is about 30% in the semi-transmissive film region. It is.

  However, in the region of the semi-transmissive film near the boundary between the semi-transmissive film and the transparent substrate, the semi-transmissive film having a phase difference of 80 degrees is compared with the semi-transmissive film having a phase difference of 80 degrees. , Exposure light intensity decreases.

  On the other hand, as shown in FIG. 5C, the thickness of the photoresist in the transparent substrate region is 0 [μm], and the thickness of the photoresist in the semi-transmissive film region is the same as that in the light shielding film region. It can be seen that three types of film thickness regions are formed by one exposure in any case.

In the transparent substrate side region near the boundary between the semi-transmissive film and the transparent substrate, the semi-transmissive film having a phase difference of 80 degrees has a greater photoresist film thickness than the semi-transmissive film having a phase difference of 30 degrees. It can be understood that it is thicker than the film thickness of the semi-transmissive film.
That is, in the region of a specific size on the transparent substrate side at the periphery of the semi-transmissive film having a phase difference of 80 degrees, the exposure light intensity is reduced as compared with the region of the semi-transmissive film. Therefore, in this region, the photoresist film thickness is formed thicker than that of the semi-transmissive film region, and the photoresist film thickness tends to decrease as the distance from the semi-transmissive film increases.

  Accordingly, when a pinhole defect having a fine specific size, for example, 2 μm or less, exists in the semi-transmissive film, the transparent substrate in the pinhole portion surrounded by the semi-transmissive film is exposed in the halftone mask. However, by setting the phase difference to 80 degrees, the photoresist film thickness corresponding to the region in the vicinity of the boundary between the semi-transmissive film and the transparent substrate has a sufficient film thickness, and by the photoresist from the periphery of the pinhole portion, As shown in the cross-sectional view of FIG. 4, pinholes are prevented from being formed in the photoresist film.

  FIG. 6 shows an enlarged view of the vicinity of the boundary between the semi-transmissive film and the transparent substrate in the photoresist film thickness distribution of FIG. In FIG. 6, the solid line indicates the shape of the photoresist film when the phase difference of the semi-transmissive film with respect to the transparent substrate is 80 degrees, and the dotted line indicates the shape of the photoresist film when the phase difference of the semi-transmissive film with respect to the transparent substrate is 30 degrees. α indicates a boundary position between the semi-transmissive film 3 and the transparent substrate 1.

As shown in FIG. 6, when the phase difference is 80 degrees compared to the phase difference of 30 degrees, the exposure light diffracted at the boundary between the semi-transmissive film and the transmissive region interferes with the exposure light transmitted through the semi-transmissive film. Since it works to suppress the exposure intensity in the vicinity of the boundary, the unresolved area of the side surface of the photoresist extends toward the transmissive area.
Therefore, the semi-permeable membrane pattern width can be determined by sizing the pattern width dimension of the semi-permeable membrane 3 in advance with respect to the design value.

  Therefore, for example, in order to realize a photoresist pattern having a design dimension determined by the characteristics of an electronic circuit (referred to as a design dimension for simplicity), a transflective film having a phase difference for avoiding pinhole defects, For example, the difference amount between the pattern width dimension of the semi-transmissive film having a phase difference of 80 degrees and the photoresist pattern width dimension formed by exposure may be reduced in advance with respect to the semi-transmissive film 3 of the halftone mask.

  FIG. 7 is a plan view of a halftone mask showing dimensional correction of the semi-transmissive film. In FIG. 7, a dotted line D indicates a pattern (or a photoresist pattern) having a design dimension. The pattern dimension of the semi-transmissive film 3 having a phase difference for avoiding pinhole defects with respect to the dotted line D is reduced by a difference amount s on each side. That is, with respect to the dotted line D, the pattern dimension is reduced by the correction amount −s (one side). By using the semi-transmissive film 3 whose dimensions have been corrected (or changed in size) in this way, the photoresist can realize a desired pattern (pattern as designed) and prevent the semi-permeable film from being opened by pinholes. be able to.

  In order to prevent photoresist defects due to pinholes in the semi-transmissive film 3, only the semi-transmissive film needs to be corrected.

  The correction amount (difference amount) depends on the transmittance of the semi-transmissive film and the NA value of the exposure apparatus. FIG. 8 shows the result of analyzing the transmittance and NA value dependence of the correction amount in the case of the phase difference of 80 degrees by simulation. The correction amount depends on the semi-transmittance and the NA of the exposure device. The absolute value of the correction amount increases as the transmittance increases, and the correction amount tends to decrease as the NA of the exposure device increases.

  Since the correction amount (difference amount) can be calculated by simulation using the transmissivity of the translucent film, the phase difference, and the NA value of the exposure apparatus, the halftone mask is designed based on the design size of the transflective film and the difference amount. The pattern of the semipermeable membrane 3 can be determined.

  Instead of using simulation, basic data on the semi-transmissivity of the photoresist pattern shape and the NA value dependency of the exposure apparatus may be acquired in advance, and the difference may be determined based on the basic data.

  When applying reduced exposure, each pattern size of the halftone mask may be multiplied by a reduction magnification.

  In the above embodiment, the halftone mask of three gradations has been described. However, the present invention is also applied to a multi-tone halftone mask of four gradations or more provided with a semi-transmissive film having different transmittances. Needless to say, you can.

  By performing size correction in this way, it is possible to obtain a halftone mask capable of realizing a photoresist shape with a designed pattern and preventing the occurrence of photoresist defects due to pinholes in the semi-transmissive film. In addition to reducing the manufacturing cost of the mask, it is possible to improve the yield of products such as flat panel displays.

1 Transparent substrate 2 Light-shielding film 3 Semi-transmissive film

Claims (6)

On the transparent substrate, with a light shielding film pattern and a semi-transmissive film pattern,
The transflective film has a transmittance of 20 to 50% and a phase difference of 60 to 90 degrees with respect to the transparent substrate. 2. The halftone mask according to claim 1, wherein a transmittance of the semi-transmissive film with respect to the transparent substrate is 30%, and a phase difference is 80 to 90 degrees.   The halftone mask according to claim 1, wherein the light shielding film is a chromium film, and the semi-transmissive film is a chromium oxide film, a nitride film, or an oxynitride film. A translucent film and a light shielding film are provided on a transparent substrate,
The half-tone mask blank is characterized in that the transflective film has a transmittance of 20 to 50% and a phase difference of 60 to 90 degrees with respect to the transparent substrate. 5. The halftone mask blank according to claim 4, wherein a transmittance of the semi-transmissive film with respect to the transparent substrate is 30% and a phase difference is 80 to 90 degrees. 4. The halftone mask according to claim 1, wherein the dimension of the pattern of the semi-transmissive film is reduced by a predetermined correction amount with respect to a design value. 5.

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