TW201812436A - Half tone mask and half tone mask blank that has a phase difference of 60 degrees to 90 degrees and a penetration rate of 20-50% with respect to a transparent substrate - Google Patents

Abstract

In an existing multiple-greyscale half tone mask, pinhole defects formed in a semi-permeable membrane are inspected and corrected with a defect inspection device and thus, it is difficult to repair fine pinhole defects that are for example smaller than inspection limit. In order to overcome such a problem, the present invention provides the following half tone mask. The semi-permeable membrane of the half tone mask is made to have a phase difference of 60 degrees to 90 degrees and a penetration rate of 20-50% with respect to a transparent substrate in order to prevent exposure of photoresist that serves as a transfer object due to pinholes smaller than a specific size on the semi-permeable membrane for reducing the risk of producing pattern defects in products.

Description

Halftone masks and halftone mask blanks

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

In the technical field of flat panel displays and the like, instead of using a phase shifter, a multi-grayscale light mask called a halftone mask (or gray-tone mask) is used. Function to limit the exposure. By using a halftone mask, photoresist patterns with different film thicknesses can be formed by a single exposure, the number of lithographic steps in the manufacturing steps of a flat panel display can be reduced, and the manufacturing cost can be reduced. Regarding such a semi-permeable film, the semi-permeable film is used as an auxiliary pattern of a pattern realized based on a light-shielding film for the purpose of improving the resolution of a fine pattern, and substantially has a phase shifter used in a binary mask. Different functions.

The half-tone mask used for this purpose is a semi-transparent film having a transmittance between the transparent substrate and the light-shielding film. For example, a three-level gray scale can be achieved by the transparent substrate, the semi-permeable film, and the light-shielding film. In addition, it is also possible to use a semi-permeable film with various transmittances to realize a half-tone mask of 4 gray levels or more.

Generally, in the manufacturing process of a photomask, when an occasional defect such as a pinhole occurs due to a foreign matter during film formation, a developing solution mist when forming a photomask pattern, and the like, the defect is used as a lithography of the photomask. In the step, it is sensitized by a photoresist as a transfer target. Therefore, after completion of the photomask, defect inspection is performed, and repair of the photomask is performed if necessary.

In the case of a half-tone mask, there has been the following technology: When a pinhole defect of a semi-permeable film is detected in the defect inspection step, a carbon film is formed at the pinhole portion by using a FIB device (focused ion beam device). To fix the defect. Patent Document 1 discloses a technique of identifying the coordinates of a pinhole defect by a defect inspection device, and forming a carbon film at the pinhole portion using a FIB device.

[Prior Art Document] [Patent Document] [Patent Document 1] Japanese Patent Laid-Open No. 2008-256759

[Problems to be Solved by the Invention] As the pattern of a flat-panel display becomes higher and the pattern becomes finer, countermeasures against poor exposure caused by fine pinholes become increasingly important. However, in general, defect detection of halftone masks is difficult compared to binary masks. That is, the defect inspection is to detect defects optically. Although the light-shielding film can detect defects by the contrast of light, the semi-transparent film has the condition of light transmission, so it is suitable for pinholes. It is difficult to detect a "white defect" in which a part of the semi-permeable membrane is missing.

Therefore, when a small amount of pinholes (white defects) that are not detected by the defect inspection device remain, as a result of the photoresist being sensitized by the halftone mask, the photoresist is sensitized at the pinhole portion, and the photoresist is present. There is a danger that the film thickness is locally thinner than the desired film thickness.

Patent Document 1 discloses a repair technology for forming a carbon film that matches the transmittance of a semi-permeable film by a FIB device at a pinhole portion. However, there are problems in that the repair steps are complicated, and when the defect size is small, the repair is difficult. . In addition, the repair technology for forming a carbon film by a FIB device is used to repair defects detected by the defect inspection device, so the defects below the sensitivity limit of the defect inspection device cannot be repaired, especially for the white of the semi-permeable membrane. For defects, there is a problem that it is difficult to detect minute defects. Therefore, it is necessary to check again whether there are any defects in the photoresist after exposure through the halftone mask.

In view of this, the present invention provides a half-tone mask and a half-tone mask blank for manufacturing the half-tone mask. The half-tone mask can prevent a fine semi-permeable membrane, for example, which is difficult to detect due to a certain size or less. Pinhole (white defect) caused by poor exposure of the photoresist film.

[Means for Solving the Problem] The present invention provides a halftone mask characterized in that a pattern of a light-shielding film and a pattern of a semi-permeable film are provided on a transparent substrate, and the transmittance of the semi-permeable film to the transparent substrate is 20% to 50%, the retardation of the semi-permeable film with respect to the transparent substrate is 60 degrees to 90 degrees.

In the halftone mask of the present invention, a transmittance of the semi-permeable film to the transparent substrate is 30%, and a phase difference of the semi-permeable film to the transparent substrate is 80 degrees to 90 degrees.

The semi-transparent film in the half-tone mask has a specific phase difference. Therefore, the semi-transparent film of the half-tone mask can be placed on the semi-transparent film of the half-tone mask due to the interference effect at the boundary between the transparent region and the specific width of the semi-transparent film region. Pinholes below a certain size do not cause image dissection on the photoresist, or converge the film thickness variation caused by the photoresist to within the allowable range of the exposure margin.

In the half-tone mask of the present invention, the light-shielding film is a chromium film, and the semi-permeable film is a chromium oxide film, a nitride film, or a oxynitride film.

By controlling and adjusting the composition and thickness of the chromium oxide film, nitride film, or oxynitride film, it is possible to form a pattern of a semi-permeable film having a desired transmittance and retardation on a half-tone mask.

In the halftone mask of the present invention, the size of the pattern of the semi-permeable membrane is reduced by a predetermined correction amount (correction value) from the design value.

By adopting such a pattern of the semi-permeable film, it is possible to eliminate the defects of the photoresist due to minute pinholes below a specific size, and to form a photoresist pattern according to a design value.

The invention also provides a half-tone mask blank, which is characterized in that it has a semi-permeable film and a light-shielding film on a transparent substrate. The transmissivity of the semi-permeable film to the transparent substrate is 20% to 50%. The phase difference with respect to the transparent substrate is 60 degrees to 90 degrees.

In the half-tone mask blank of the present invention, the transmissivity of the semi-permeable film to the transparent substrate is 30%, and the phase difference of the semi-permeable film to the transparent substrate is 80 degrees to 90 degrees.

By using such a halftone mask blank and selecting a semi-permeable membrane that matches the specifications to produce a half-tone mask, it is possible to produce low-cost half-tones that prevent fine pinholes below the specific size of the semi-permeable membrane from being resolved. Matte.

[Effects of the Invention] In summary, according to the present invention, it is possible to provide a halftone mask blank and a halftone mask at a low cost, which target pinholes below a certain size, especially below the detection limit that was difficult to repair in the past. Pinholes can also prevent pattern abnormalities caused by transfer. As a result, it is possible to provide a halftone mask in which the risk of pattern defects in a product can be reduced in the lithography step using the halftone mask of the present invention.

(Principle of Solving the Problem) According to the halftone mask of the present invention, a phase difference from a transparent substrate is set in a specific region for a semi-permeable film having a predetermined transmittance with respect to exposure, thereby avoiding a specific size or less The pinholes are resolved on the photoresist. Therefore, it is not necessary to repair the pinholes of the semi-permeable membrane, and it is possible to prevent the photoresist from generating defects due to the pinholes.

That is, due to the interference effect of the exposure of the transparent region and the semi-permeable membrane region, the transmission intensity of the exposure near the boundary between the transparent region and the semi-transmissive region is reduced, thereby lowering the lower limit of the resolution of the semi-permeable membrane to the hole shape. The value is set to be larger than the specific pinhole size of the target, thereby preventing pinholes smaller than the specific pinhole size from being resolved on the photoresist, and opening the photoresist (the film thickness becomes zero or less than the allowable lower limit).

In addition, on the other hand, in a region near the pinhole, particularly in a region of a semi-permeable film surrounding the pinhole, the exposure intensity decreases, and thus the thickness of the photoresist film may increase. Therefore, for the transmittance of the semi-permeable membrane and for the photoresist to be patterned by the lithography step, the range of the phase shift of the semi-permeable membrane is set to the optimal range, so that the needle The thickness of the photoresist film in a corresponding portion near the hole is within an allowable range, and therefore, countermeasures against pinhole defects in the semi-permeable film are performed.

Therefore, the conventional method of detecting pinholes of a semi-permeable film of a light mask and repairing the pinholes as in the past is used to prevent defects in the photoresist.

In this way, the problem-solving method of the present invention is to prevent the defect of the photoresist by adjusting the resolution near the pinhole. Therefore, the optimal range of the phase shift of the semi-permeable film also depends on the target semi-permeable film. Pinhole size. As an example, the transmittance of a semi-permeable film is determined according to the film thickness of a necessary photoresist. The transmittance of a semi-permeable film of a halftone mask is generally set to a value of about 30%. Therefore, the transmittance is hereinafter referred to as 30% The case will be described in detail as an example. In addition, a case will be explained in which, as the pinhole size, focusing on the size corresponding to the lower limit value of the previous defect inspection device, the pinholes of the semi-permeable membrane that could not be repaired in principle in the prior art can also be focused on. Avoid pinhole defects caused by photoresist.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. However, each of the embodiments and examples does not provide a limited explanation in the determination of the gist of the present invention. In addition, the same reference numerals are given to the same or the same components, and the description is omitted.

FIG. 1 shows a cross-sectional shape of a three-tone grayscale halftone mask. According to the conventional manufacturing technique, a pattern of a light-shielding film 2 made of, for example, a chromium film and the like, and a pattern of a semi-permeable film 3 made of, for example, chromium oxide are formed on the transparent substrate 1.

An example of the manufacturing process of a gray scale halftone mask is shown below. (1) First, prepare a light-shielding blank covering the entire surface of the transparent substrate 1 with a light-shielding film 2. A first photoresist pattern is formed on the light-shielding film 2 and the exposed light-shielding film 2 is used as a mask. Etching is performed to form a light-shielding pattern. (2) Next, after the remaining first photoresist pattern is removed, a semi-permeable film 3 covering the transparent substrate 1 and the light-shielding film 2 is formed. (3) Next, a second photoresist pattern is formed on the semi-permeable film 3, and the exposed semi-permeable film 3 is etched as a mask to form a semi-transparent pattern.

In addition, a semi-permeable film 3 and a light-shielding film 2 may be sequentially formed on the transparent substrate 1 and a photoresist pattern may be used for etching in the order of the light-shielding film 2 and the semi-permeable film 3 to form a half-tone mask. An etching stopper film is interposed between the film and the light-shielding film, and is made of at least the same kind of film material. In addition, the light-shielding film is not limited to a single layer, as long as it has a structure that satisfies an optical density of 3.0 or more.

FIG. 2 shows the phase difference dependency of the intensity of the exposure (transmitted light) transmitted from the pinhole (white defect) diameter of 0.5 to 2 μm when the transmittance of the semipermeable film 3 is 30%. Symbols ◇, □, △, and ○ in the figure represent exposure intensities of pinhole diameters (defect sizes) of 2.0, 1.5, 1.0, and 0.5 μm, respectively. In addition, the transmittance is the transmittance of the semi-permeable film 3 when the transmittance of the transparent substrate 1 to the exposure is 100%, and the phase difference is the phase difference of the semi-permeable film 3 with respect to the transparent substrate 1. In addition, the wavelength of exposure is a mixed wavelength of the i to g lines.

In FIG. 2, the dotted lines A and B indicate the upper and lower limits of the allowable range of the exposure intensity. When the upper limit is exceeded, the photoresist is photosensitive, and the film thickness is greatly reduced (opening) to become a white defect. When it is lower than the lower limit, the exposure amount is insufficient, and the photoresist film thickness is increased to become a black defect.

As can be seen from FIG. 2, the condition that the variation in the film thickness of the photoresist converges within the allowable range of the exposure margin is that when the diameter of the pinhole is 0.5 μm, the phase difference is at least within the range of 30 degrees to 120 degrees. In the case where the diameter of the pinhole is 1.0 μm, the phase difference is in the range of 30 degrees to 90 degrees, and in the case of the diameter of the pinhole is 1.5 μm, the phase difference is in the range of 60 degrees to 90 degrees. When the pinhole diameter is 2.0 μm, the phase difference is in the range of 80 degrees to 110 degrees.

For example, the detection sensitivity of the defect inspection device is 1.5 μm, and pinhole repair below the detection sensitivity is difficult. However, if the phase difference between the semi-permeable membrane and the transmissive membrane is set to 60 degrees to 90 degrees (one point chain in FIG. 2) Line range), such pinholes will not sensitize the photoresist. Alternatively, even if a pinhole of 1.5 μm is detected in a defect inspection device, it does not need to be repaired because it does not become a defect in the photoresist as a transfer target.

In addition, in order to allow the semi-permeable membrane 3 to further allow pinholes with a larger diameter of 2.0 μm, a phase difference of 80 degrees to 90 degrees may be set. Therefore, regardless of the detection sensitivity of the defect inspection device, an appropriate pinhole size can be determined corresponding to the minimum size as a repair target, and the transmittance and phase difference can be set in cooperation with it.

FIG. 3 shows the surface shape of a photoresist in the case of exposure through a half-tone mask. The half-tone mask is present on the semi-permeable film 3 having a transmittance of 30%, a phase difference of 30 degrees, and 80 degrees. Pinholes of various diameters. It can be understood that in the case of a phase difference of 30 degrees, a pinhole with a diameter of 2.0 μm sensitizes the photoresist of the object to be transferred and opens holes in the photoresist film. However, in the case of a phase difference of 80 degrees, The pinhole on the photoresist as the object to be transferred will not be resolved, preventing the photoresist from opening.

FIG. 4 shows a cross-sectional shape of a portion of the photoresist corresponding to the pinhole portion using a halftone mask having pinholes having a diameter of 2 μm on the semipermeable membrane. The solid line shows a transmittance of 30% and a phase difference. The cross-sectional shape of the photoresist film thickness in the case of a 80-degree semi-permeable film, and the dashed line shows the cross-sectional shape of the photoresist film thickness in the case of a semi-permeable film with a transmittance of 30% and a phase difference of 30 degrees.

In the case of a semi-permeable film with a retardation of 30 degrees, there are openings with a photoresist film thickness of 0 (zero). However, in the case of a semi-permeable film with a retardation of 80 degrees, there are no openings. With sufficient film thickness, white defects can be avoided, and film thickness variation is within the allowable range of exposure margin.

As described above, the larger the size of the white defect to be allowed, the stricter the control of the phase difference is required. When the transmittance of the semi-permeable membrane 3 changes, the value of the optimal phase difference also changes. For example, when it is desired to allow a pinhole size of 1.5 μm, for a semi-transmissive film with a transmittance of 30%, the phase difference that satisfies the exposure margin is 60 degrees to 80 degrees, and it is desired to further allow a larger size of 2.0 μm. In this case, the phase difference needs to be controlled at 80 degrees. On the other hand, for a semi-permeable membrane 3 having a transmittance of 50%, when the pinhole size is desired to be 1.5 μm, the phase difference ranges from 50 ° to 70 °, and when the pinhole size is desired to be 2.0 μm, it is optimal. The phase difference is 60 degrees.

In this way, the range and optimal value of the phase to be controlled are changed according to the transmittance and the desired pinhole size. The optimal phase difference when the pinhole size is to be 2.0 μm is allowed to pass through the semi-permeable membrane. When the rate is 10%, 20%, 30%, 40%, or 50%, the optimum phase difference is 100 degrees, 90 degrees, 80 degrees, 70 degrees, and 60 degrees. The transmittance of the semi-permeable membrane can be selected according to the customer's expectation, and the phase difference can be determined for the transmittance.

As described above, by adjusting the retardation of the semi-permeable membrane 3, even if there are pinholes having a diameter below the detection limit of the inspection device, it is possible to prevent the occurrence of defective film thickness of the photoresist.

Therefore, from the half-tone mask blank on which the semi-permeable film 3 and the light-shielding film 2 are formed on the transparent substrate 1, a transmissivity that matches the specification of the mask (or customer's request) is selected to manufacture a half-tone mask. Therefore, the defects of the photoresist caused by the pinholes below the detection limit can be avoided, wherein the phase difference and transmittance of the semi-permeable film 3 with respect to the transparent substrate 1 are 60 degrees to 90 degrees and 20%, respectively. ~ 50%. As a result, the cost of the correction step of the halftone mask can be significantly reduced, and the product yield can be improved.

In addition, the transmittance and phase difference can be controlled by the thickness and composition of the semi-permeable film, and by controlling the transmittance and phase difference respectively, a desired semi-permeable film can be obtained. For example, by measuring and documenting the retardation and transmittance of films with different film thicknesses and compositions in advance, a semi-permeable film that matches the specifications of the half-tone mask can be formed.

As such a semi-permeable film, for example, an oxide film such as chromium (Cr), titanium (Ti), nickel (Ni), molybdenum (Mo), a nitride film, a nitrogen oxide film, or a carbon oxide film can be used to adjust oxygen and nitrogen. , Carbon, composition and film thickness are sufficient.

These films can be formed by a reactive sputtering method. For example, in the adjustment of the composition of the chromium oxynitride film, chromium can be used as a target, and a film obtained by mixing a gas obtained by mixing oxygen, nitrogen, or nitrous oxide in argon can be formed by a sputtering method. Mixing ratio (partial pressure) enables composition control. In addition, for example, in the case of a chromium oxide film, a mixed gas of argon and oxygen may be used, and in the case of a chromium nitride film, a mixed gas of argon and nitrogen may be used. In this case, a mixed gas of argon, oxygen, and carbon dioxide may be used. The same applies to other metals.

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

The mechanism for avoiding defects in the photoresist caused by the pinholes of the semi-permeable membrane will be described in detail below.

FIG. 5 shows (a) a halftone mask having a pattern of a light-shielding film and a semi-permeable film on a transparent substrate, and (b) exposure intensity distribution and (c) exposure when the halftone mask is used for exposure. Film thickness distribution of post-developed photoresist. In (b) and (c) of FIG. 5, the solid line indicates the exposure intensity and the film thickness distribution of the photoresist film when the retardation of the semi-permeable film with respect to the transparent substrate is 80 degrees, and the dotted line indicates that the semi-permeable film is transparent. The exposure intensity and the thickness distribution of the photoresist film when the retardation of the substrate was 30 degrees. In addition, the transmittance of the semi-permeable membrane was 30%, and the exposure wavelength was a mixed wavelength of i-line to g-line, and NA = 0.1.

As shown in FIG. 5 (b), in either case, the exposure intensity is 0 in the area of the light-shielding film of the halftone mask, and the exposure intensity is approximately 30% in the area of the semi-permeable film.

However, in the region of the semi-permeable membrane near the boundary between the semi-permeable membrane and the transparent substrate, compared to a semi-permeable membrane with a phase difference of 30 degrees, the interference effect is caused in the case of a semi-permeable membrane with a phase difference of 80 degrees. , The exposure intensity decreases.

On the other hand, as shown in FIG. 5 (c), it can be seen that the film thickness of the photoresist in the region of the transparent substrate is 0 μm μ, and the film thickness of the photoresist in the region of the semi-permeable film is light in the region of the light-shielding film. In either case, the film thickness between the film thicknesses of the resist is formed into three types of film thickness regions by one exposure.

It can be understood that, in a region on the transparent substrate side near the boundary between the semi-permeable film and the transparent substrate, the thickness of the photoresist film of the semi-permeable film having a retardation of 80 degrees is increased compared to the semi-permeable film having a retardation of 30 degrees. Larger and thicker than the photoresist film thickness of the semi-permeable film. That is, in a specific-size area on the transparent substrate side of the periphery of the semi-permeable film having a phase difference of 80 degrees, the exposure intensity is reduced compared to the area of the semi-permeable film. Therefore, compared to the thickness of the photoresist film in the area of the semi-permeable film, the photoresist film thickness in the area of the specific size is formed to be thicker, and further, the photoresist is present as the film is away from the semi-permeable film. The agent film thickness tends to decrease.

Therefore, when there is a minute specific size on the semi-permeable membrane, for example, pinhole defects of 2 μm or less, a transparent substrate with a pin-hole portion surrounded by the semi-permeable membrane is exposed in a half-tone mask. However, by setting the retardation to 80 degrees, the photoresist film thickness equivalent to the area near the boundary between the semi-permeable film and the transparent substrate has a sufficient film thickness, as shown in the cross-sectional view of FIG. The photoresist around the hole prevents the formation of pinholes in the photoresist film.

FIG. 6 is an enlarged view of the vicinity of the boundary between the semi-permeable film and the transparent substrate in the photoresist film thickness distribution of FIG. 5 (c). In FIG. 6, the solid line shows the shape of the photoresist film when the retardation of the semi-permeable film with respect to the transparent substrate is 80 degrees, and the dotted line shows the light when the retardation of the semi-permeable film with respect to the transparent substrate is 30 degrees. In the shape of the resist film, a dot chain line α indicates a boundary position between the semi-permeable film 3 and the transparent substrate 1.

As shown in FIG. 6, when the phase difference is 30 degrees and the phase difference is 80 degrees, when the diffracted exposure at the boundary between the semi-transmissive film and the transmission region and the exposure through the semi-transmissive film interfere, Since the effect of suppressing the exposure intensity near the boundary is exerted, the non-resolution region on the side of the photoresist expands toward the transmission region side. Therefore, the size of the pattern width of the semi-permeable membrane 3 is adjusted according to a predetermined design value, whereby the pattern width of the semi-permeable membrane can be determined.

Therefore, in order to realize a photoresist pattern having a design size (designed simply for design simplicity) of a design value determined based on characteristics of an electronic circuit, the semi-permeable film 3 of the halftone mask is reduced in advance to have a photoresist pattern. A semi-transmissive film having a retardation for avoiding pinhole defects is sufficient, for example, a difference between a pattern width dimension of the semi-transparent film having a retardation of 80 degrees and a width dimension of a photoresist pattern formed by exposure.

FIG. 7 is a plan view of a halftone mask showing the size correction of the semipermeable membrane. In FIG. 7, a dotted line D indicates a design-size pattern (or a photoresist pattern). With respect to the dotted line D, the pattern size of the semi-permeable film 3 having a phase difference for avoiding pinhole defects is reduced by a difference s on each side. That is, the pattern size is reduced by only the correction amount -s (one side) with respect to the dotted line D. In this way, by using the semi-permeable film 3 that has been dimensionally corrected (or changed in size), the photoresist can achieve a desired pattern (a pattern according to a design size), and can prevent the pinhole caused by the semi-permeable film. Opening.

In addition, in order to prevent the defect of the photoresist due to the pinhole of the semi-permeable membrane 3, only the size of the semi-permeable membrane may be corrected.

The correction amount (difference amount) depends on the transmittance of the semi-permeable membrane and the NA value of the exposure device. FIG. 8 shows the results of analyzing the dependence of the correction amount on the transmittance and the NA value when the phase difference is 80 degrees by simulation. The correction amount depends on the semi-transmittance and the NA of the exposure machine, and there is a tendency that as the transmittance increases, the absolute value of the correction amount increases, and as the NA of the exposure machine increases, the correction amount decreases.

Since the correction amount (difference amount) can be calculated using the transmittance, phase difference, and NA value of the exposure machine through simulation, the halftone mask can be determined based on the design size of the semi-transmissive film and the difference amount. On the semi-permeable membrane 3.

In addition, basic data on the half transmittance of the photoresist pattern shape and the NA value dependence of the exposure device may be obtained in advance without simulation, and the difference may be determined based on the basic data.

In addition, when applying reduced exposure, it is sufficient to multiply the size of each pattern of the halftone mask by the reduction magnification.

In addition, in the above-mentioned embodiment, the three-tone half-tone mask has been described. However, it goes without saying that the present invention can also be applied to a multi-gray-tone half-tone having four or more gray-scales having a semi-transmissive film having a different transmittance. In tonal mask.

By performing such a size correction, a photoresist shape according to the designed pattern can be realized, and a halftone mask capable of preventing photoresist defects due to pinholes of the semi-permeable film can be obtained, in addition to reducing the manufacturing cost of the mask Product yields such as flat panel displays can also be improved.

1‧‧‧ transparent substrate

2‧‧‧ light-shielding film

3‧‧‧ semi-permeable membrane

FIG. 1 is a cross-sectional view of a three-tone halftone mask. FIG. 2 is a graph showing a phase difference dependency of an exposure intensity of a pinhole portion. FIG. 3 is a diagram showing the pinhole dependency of the surface shape of a photoresist. FIG. 4 is a diagram showing a phase difference dependency of a cross-sectional shape of a photoresist. FIG. 5 is a graph showing a phase difference dependency of an exposure intensity using a halftone mask and a photoresist film thickness distribution. FIG. 6 is a diagram showing a phase difference dependency of a photoresist film thickness distribution near a boundary between a transparent substrate and a semi-permeable film. FIG. 7 is a plan view showing the size correction of a semi-permeable film of a half-tone mask. FIG. 8 is a graph showing the transmittance and NA dependency of the size correction amount of the semi-permeable membrane.

Claims (6)

A half-tone mask comprising a pattern of a light-shielding film and a pattern of a semi-permeable film on a transparent substrate, wherein the transmittance of the semi-permeable film to the transparent substrate is 20% to 50%, and the semi-permeable film is relatively The phase difference on the transparent substrate is 60 degrees to 90 degrees. The halftone mask according to claim 1, wherein a transmittance of the semi-permeable film to the transparent substrate is 30%, and a phase difference of the semi-permeable film to the transparent substrate is 80 degrees to 90 degrees. The halftone mask according to claim 1 or 2, wherein the light-shielding film is a chromium film, and the semi-permeable film is an oxide film, a nitride film, or an oxynitride film of chromium. The halftone mask according to any one of claims 1 to 3, wherein the size of the pattern of the semi-permeable membrane is reduced by a predetermined correction amount relative to a design value. A half-tone mask blank, comprising: a semi-permeable film and a light-shielding film on a transparent substrate; a transmittance of the semi-permeable film to the transparent substrate is 20% to 50%; and the semi-permeable film is transparent to the transparent material. The phase difference of the substrate is 60 degrees to 90 degrees. The halftone mask blank according to claim 5, wherein a transmittance of the semi-permeable film to the transparent substrate is 30%, and a phase difference of the semi-permeable film to the transparent substrate is 80 degrees to 90 degrees.