TW201310164A - Photomask substrate, method of manufacturing a photomask substrate, photomask blank, photomask, pattern transfer method, method of manufacturing liquid crystal display, and proximity gap evaluating method - Google Patents

Abstract

Even a miniaturized transfer pattern is transferred in exact conformity with designed pattern values with high accuracy. A photomask substrate is formed into a photomask. The photomask has a main surface provided with a transfer pattern. The photomask is mounted to a proximity exposure apparatus and used in transferring the transfer pattern by exposure with a proximity gap formed between the photomask and an object mounted on a stage of the exposure apparatus. In one or a plurality of specific regions on the main surface, shaping is performed in a removing amount different from that in a peripheral region except the specific region to form a concave shape, a convex shape, or a concave-convex shape. In this manner, it is possible to reduce the variation of the proximity gap due to a position thereof, which is caused when the photomask substrate is mounted to the exposure apparatus. The shaping is performed in order to reduce the variation inherent to the exposure apparatus, which is extracted from the variation of the proximity gap due to its position.

Description

Photomask substrate, method of manufacturing photomask substrate, mask base, photomask, pattern transfer method, method of manufacturing liquid crystal display device, and proximity gap evaluation method

The present invention relates to a photomask substrate used for a photomask or the like for a liquid crystal display device. In particular, when a pattern transfer is performed using a proximity exposure device, a mask substrate having improved shape accuracy (line width accuracy, coordinate accuracy, etc.) of a pattern formed on a transfer target body, and light using the same are used. A photomask blank, a method of manufacturing a photomask, and a pattern transfer method.

Patent Document 1 describes a bending correction mechanism for reducing the curvature due to the weight of the mask itself in a proximity exposure machine in which the mask and the object to be transferred are placed close to each other, and each of the sides of the mask is held. a side mask holder and two bending correction bars (bars) for pressing the edges of the masks held on the mask holder from above (refer to FIG. 1(a)(b)) .

Patent Document 2 describes a mask holding device for correcting curvature of a mask in a proximity exposure apparatus. Here, it is described that a mask holder having a frame shape of substantially the same size as the photomask holds a mask, and an airtight chamber is formed above the mask, and the difference between the air pressure of the airtight chamber and the external air pressure is used to match the mask. The method of self-weight balancing causes the reticle to float and correct the bending (refer to Figure 2).

Patent Document 3 describes a glass substrate in which the substrate is bent and the desired flatness is not obtained when the photomask substrate having a large size is horizontally held in the exposure apparatus, and the substrate is made flat.

[Advanced technical literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2009-260172

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2003-131388

[Patent Document 3] Patent No. 4362732

Recently, in the manufacture of display devices such as liquid crystal display devices, production efficiency and high transfer precision have been improved by increasing the size of the photomask used. The liquid crystal display device has a structure in which a TFT substrate on which a TFT (thin film transistor) array is formed and a CF (color filter) on which an RGB pattern is formed are attached, and a liquid crystal is sealed therebetween. Such a TFT substrate or a CF system is manufactured by using a plurality of photomasks by a photolithography step. In recent years, with the increase in the brightness and the speed of the liquid crystal display device of the final product, the pattern of the photomask has become finer, and the requirements for line width accuracy and coordinate accuracy as a result of the transfer have become stricter.

Therefore, an object of the present invention is to provide a mask substrate which can be transferred with high precision in pattern design value, a method of manufacturing a mask base and a mask using the same, and a method of using the same. Pattern transfer method, etc.

A first aspect of the present invention is a photomask substrate which is formed on a main surface to form a transfer pattern, is mounted on a proximity exposure device, and is disposed between a transfer target placed on a pedestal of the proximity exposure device. Exposing with a proximity gap to transfer the transfer pattern In the mask used, a shape of a removal amount different from a peripheral region outside the specific region is formed in one or a plurality of specific regions on the main surface to form a concave shape, a convex shape, or a concave-convex shape. Reducing a variation caused by a position of the proximity gap generated when the mask substrate is attached to the proximity exposure apparatus, and the shape processing system reduces the variation caused by the position of the proximity gap, and the proximity exposure apparatus is inherently Changer.

A second aspect of the present invention is the photomask substrate according to the first aspect, wherein the main surface subjected to the shape processing has a correction shape determined based on a variation inherent in the proximity exposure device.

A third aspect of the present invention is the photomask substrate according to the first or second aspect, wherein the shape processing is performed only on a variation of the proximity of the proximity exposure device including the aforesaid main surface on the main surface exceeding a specific gap (gap) A specific area of the area where the allowable value is changed.

A fourth aspect of the invention is the photomask substrate according to any one of the first to third aspect, wherein the shape processing is performed by forming one or a plurality of recesses on the main surface.

A fifth aspect of the present invention provides a method of manufacturing a photomask substrate, wherein the photomask substrate is a photomask having a transfer pattern formed on a main surface thereof, and is mounted on a proximity exposure device, and is placed on the proximity A light-shield used for transferring the transfer pattern is formed by providing a close gap between the transfer bodies of the pedestal of the exposure apparatus, and the method of manufacturing the mask substrate is Measuring a near gap of the plurality of positions on the main surface, and absorbing a variation inherent in the proximity exposure device due to a change in position of the proximity gap, based on the inherent variation of the proximity exposure device and the tolerance of the specific gap variation The value of the correction is determined by the shape of the main surface of the mask substrate, and the shape of the modified shape determined as described above is processed on the main surface of the mask substrate.

According to a sixth aspect of the present invention, in a method of manufacturing a photomask substrate, the photomask substrate is a photomask having a transfer pattern formed on a main surface thereof, and is mounted on a proximity exposure device, and is placed on the proximity The photoreceptor used for transferring the transfer pattern is formed by providing a close gap between the transfer bodies of the pedestal of the exposure device, and the method for manufacturing the photomask substrate includes the following steps: a sample mask substrate is mounted on the proximity exposure device, and a sample glass substrate is placed on a stage of the proximity exposure device, and a plurality of main surfaces of the sample mask substrate are measured. Positioning the adjacent gap to obtain the void data indicating the change of the adjacent gap caused by the position; extracting the variation component inherent to the proximity exposure device from the gap data to obtain the inherent void data; and using the inherent void data Obtaining shape processing data for the mask substrate with a specific gap variation allowable value; and using the shape processing data to form the mask base Processing the shape of the main surface.

According to a seventh aspect of the present invention, in a method of manufacturing a photomask substrate according to the sixth aspect, in the step of obtaining the inherent void data, the variation of the adjacent gaps of the plurality of positions is caused by the sample mask substrate. Component removal in the vicinity of the gap change.

The eighth aspect of the present invention is the method of manufacturing the reticle substrate of the sixth or seventh aspect, wherein in the step of obtaining the inherent void data, the variation of the adjacent gap of the plurality of positions is caused by the sample glass substrate The components of the adjacent gap change are removed.

The ninth aspect of the invention is the method of manufacturing the photomask substrate according to any one of the sixth to eighth aspect, wherein the measurement of the proximity gap is performed to suppress bending due to the weight of the sample mask substrate. The bending suppression mechanism provided in the proximity exposure device.

The ninth aspect of the invention is the method of manufacturing the reticle substrate according to any one of the sixth to ninth aspect, wherein the step of obtaining the shape processing data specifies the inherent proximity of the proximity exposure device The portion exceeding the allowable value of the gap variation in the close gap change caused by the position is subjected to shape processing on a specific region including the specific portion.

The eleventh aspect of the invention is the method of manufacturing the reticle substrate according to any one of the sixth to tenth aspect, wherein the height of the main surface at a position where the close gap is at a maximum value is Z1, Let the aforementioned gap variation allowable value be T In the case of the above-mentioned main surface, the portion having a height lower than (Z1-T) is specified, and the specific region including the aforementioned specific portion is subjected to shape processing.

A twelfth aspect of the invention is the method of manufacturing a reticle substrate according to any one of the fifth aspect, wherein the shape processing is performed by forming one or a plurality of recesses on a main surface of the reticle substrate.

The ninth aspect of the present invention is a reticle substrate, which is a reticle substrate produced by the reticle substrate of any of the first to fourth aspects or the manufacturing method of any of the fifth to twelfth aspects On the main surface, an optical film for forming the transfer pattern is formed.

A fourteenth aspect of the present invention is a photomask which is formed by patterning an optical film formed on a main surface of a reticle base of the thirteenth aspect by photolithography pattern.

A fifteenth aspect of the invention is the photomask of the fourteenth aspect, which is used for the manufacture of a liquid crystal display device.

A sixteenth aspect of the present invention is a pattern transfer method which is formed by attaching a photomask of a fifteenth aspect to the proximity exposure apparatus used for the measurement of the proximity gap, and exposing the light to the light The transfer pattern of the cover is transferred onto the transfer target.

A seventeenth aspect of the invention is a method of manufacturing a liquid crystal display device using the pattern transfer method of the sixteenth aspect.

An eighteenth aspect of the present invention is a proximity gap evaluation method, which is a proximity gap evaluation method of a proximity exposure apparatus, comprising the following steps: Mounting the sample mask substrate on the proximity exposure device, and placing the sample glass substrate on the pedestal of the proximity exposure device, by measuring the close gap of the plurality of positions of the main surface of the sample mask substrate, The void data of the proximity gap change caused by the position; obtaining the inherent void data from the gap data, and obtaining the inherent void data; and using the inherent void data and the specific gap variation allowable value to exceed the variation allowable value The proximity gap creates a position and an excess thereof.

According to the present invention, when the transfer pattern having the mask is transferred to the object to be transferred by the proximity exposure, the transfer accuracy can be improved by controlling the proximity gap within a certain numerical range. In particular, variations in the proximity gaps caused by the exposure device used can be greatly reduced.

(Importance of close gap uniformity)

When manufacturing the above TFT substrate or CF, it is advantageous to use a pattern transfer method using proximity exposure. In the proximity exposure, the transfer target (hereinafter also referred to as a glass substrate) on which a resist film is formed is placed facing the pattern of the photomask, and the pattern surface faces downward, from the back side of the mask (pattern formation) The side opposite to the side of the face is irradiated with light to transfer a pattern on the resist film. At this time, a specific minute interval (near gap) is provided between the photomask and the transfer body. The proximal gap is, for example, about 30 to 300 μm, more preferably about 50 to 180 μm. Further, the photomask is formed by specifically patterning an optical film (a light-shielding film or a semi-transmissive film that transmits a part of the light for exposure) formed on the main surface of the transparent substrate. Transfer pattern. The main surface on which the transfer pattern is formed becomes a pattern surface.

According to the proximity exposure method, the pattern transfer can be performed with high transfer precision if the above-mentioned close gap is uniformly maintained in the entire pattern surface, and if the near gap is uniformly maintained, the near gap is small. By setting, the point of consideration of the transfer pattern having a higher resolution can be obtained, and the importance of controlling the in-plane deviation of the adjacent gap (that is, the change of the adjacent gap caused by the difference in position) is increased. However, it is not easy to uniformly maintain the close gap in the plane.

For example, the photomask substrate of the present invention can be advantageously applied to a photomask for manufacturing a display device such as a liquid crystal display device, and the size of the main surface thereof can be, for example, a long side L1 of 600 to 1400 mm, a short side L2 of 500 to 1300 mm, and a thickness T of 5~13 mm or so. Such an increase in the size of the mask is accompanied by a tendency to increase in weight, and it is becoming a problem to suppress the fluctuation of the close gap at the time of transfer.

(How to maintain the exposure device)

There are a plurality of means for mounting (holding in the device) the reticle on the proximity exposure device.

In general, in the case where the photomask is attached to the proximity exposure device, the holding member of the exposure device holds the outer side of the region (also referred to as a pattern region) where the transfer pattern is formed on the pattern surface. For example, in the device described in Patent Document 1, when the vicinity of each of the opposite sides of the main surface of the square of the mask 1 is used as the holding region (two sides are held), the holding member of the exposure apparatus is The reticle holder 2 abuts against the holding area from the lower side (the lower surface is held), and the reticle can be held. The abutting surface of the photomask and the holding member can be adsorbed under reduced pressure (refer to Japanese Laid-Open Patent Publication No. 2010-2571), or as shown in Fig. 1(b), or tangentially abutted. In this case, the surface is kept, the mask is protected by 2 The holding member is held from below to maintain a specific close gap with the glass substrate on the one hand, and is disposed in the exposure device in a substantially horizontal posture. Alternatively, the vicinity of the four sides of the main surface may be held from below (four sides are held).

In the device described in Patent Document 2, for example, the outer side of the pattern region of the mask M and the side of the back surface (the surface opposite to the pattern surface) are used as the holding regions, and the holding member is a mask holder. 4 Contact with the upper surface (holding of the upper surface), the contact faces are attracted and adsorbed via the mask adsorption path 1a, so that the mask M can be supported from the upper surface side.

(Bending suppression mechanism of exposure device and its effect)

As is apparent from the above documents 1 to 3, when the photomask substrate is attached to a proximity exposure device (hereinafter simply referred to as an exposure device), the photomask substrate is bent by its own weight. In response to this, there has been provided an exposure apparatus provided with a bending suppressing mechanism that suppresses bending of a mask substrate attached to an exposure apparatus.

For example, in the apparatus of Patent Document 1 shown in FIG. 1, the reticle holder 2 that holds the reticle 1 from the lower surface and holds the two sides of the reticle is pressed, and the edge of both sides of the reticle 1 is pressed from above. The two bending correction levers 3 are bent and corrected by the principle of leverage.

Further, in the apparatus of Patent Document 2 shown in FIG. 2, when the mask M is held (adsorbed) from the upper surface, the airtight chamber SA is formed above the mask M, and the airtight chamber SA is passed through the air suction path 1b. The inner exhaust gas is floated in a direction opposite to the direction of gravity by the negative pressure of the airtight chamber SA, and the manner in which the mask M is bent is corrected.

Therefore, the inventors simulated the relationship between the bending suppression mechanism and the bending of the mask substrate. The holding member to which the above two sides are held is applied A simulation of the bending suppression mechanism for bending suppression by the principle of leverage is shown in FIG. Fig. 3(a) shows a state in which the photomask substrate is attached to the proximity exposure device. The photomask substrate is supported from below by a holding member supported from below at the opposite sides (two sides apart from 800 mm). Then, the curvature of the mask substrate when the force pressed from above is gradually changed on the outer side of the holding member is calculated. The horizontal axis of Fig. 3(b) indicates the position (mm) on the mask substrate, and the vertical axis indicates the amount of bending (μm). Further, each line segment in the figure indicates a bending condition when the pressure is changed, and the pressing is based on the pressure at which the bending becomes zero (1).

As shown in Fig. 3(b), when the pressure applied from above is gradually increased, the amount of bending along with the central portion of the mask substrate is gradually reduced, and the bending is substantially eliminated at a certain point in time. If the pressure is further increased, the mask substrate is warped upward in the opposite direction.

As described above, it is understood that the in-plane inhomogeneity of the adjacent gap due to the bending of the mask substrate can be reduced by appropriately applying the bending suppressing mechanism provided in the exposure apparatus. In other words, if the cause of the change in the position of the proximity gap is due to the bending of the mask substrate itself, it is considered that the bending suppression mechanism of the exposure apparatus can suppress the fluctuation to some extent.

The inventors of the present invention have further expanded the knowledge, and have been able to perform high-precision high-definition pattern transfer of the photomask substrate with higher difficulty in managing the fluctuation of the position of the adjacent gap. That is, in order to improve the transfer accuracy, it is considered that the mechanism for suppressing the bending due to the weight of the photomask substrate as described above is insufficient, and a positive review is made.

(It is considered that only the bending suppression mechanism is insufficient basis)

Membrane holding mode or bending suppression mechanism of such an exposure device There are a plurality of shapes, and therefore, depending on the difference, the direction and magnitude of the force applied to the mask substrate and the pressure of each area are not the same. Therefore, it is considered that even if the bending suppression mechanism completely eliminates the bending of its own weight, the mask substrate is subjected to the contact (or the cut surface, the tangential line) of the holding member with the exposure device, and the contact (or the cut surface, the tangent line) with the bending suppression mechanism. Different kinds of forces. Further, it is presumed that the direction and magnitude of the force applied to the mask substrate and the pressure of each area differ depending on the manner in which the mask is held by the exposure device or the bending suppression mechanism. Further, it is estimated that the same holding method or the like differs depending on the size of the mask substrate or the holding method of each exposure apparatus. Further, since the pedestal on which the exposure apparatus for arranging the glass substrate of the transfer target is placed is not completely flat, it has a cause of affecting the adjacent gap. It is considered that such a cause causes a change in the position of the close gap, which affects the transfer accuracy. In particular, in the fine transfer of a pattern having a line width of 2 to 15 μm and further about 3 to 10 μm, the near-space gap due to various causes of the exposure apparatus cannot be ignored.

In view of the above, only the bending suppression mechanism described in Patent Document 1 or Patent Document 2 has insufficient control of the adjacent gap. In addition, even with the substrate of the "a cross-sectional arc shape in which the surface of the mother glass is recessed on the opposite side of the mother glass" described in Patent Document 3, it is not possible to reliably suppress the fluctuation of the adjacent gap due to reasons other than its own weight.

Therefore, the inventors of the present invention actively studied to suppress the in-plane variation of the close gap, and obtained the following solutions. Hereinafter, an embodiment of the present invention will be described.

(To obtain the process of the photomask substrate of the embodiment)

As a material applied to the mask substrate of the present embodiment, a glass material can be used. For example, silica glass, alkali-free glass, borosilicate glass, aluminosilicate glass, or soda-lime glass can be used.

In the present application, the term "mask substrate" as a material of the mask base refers to a state in which a surface of a flat plate such as glass is processed into a transparent substrate having a specific shape and flatness. However, in a state in which a thin film is formed on the photomask substrate in this state or a resist is applied (a photomask substrate), the state in which the thin film is patterned (photomask) is substantially the same in the photomask substrate portion. Therefore, it is sometimes referred to as a photomask substrate as appropriate.

The photomask substrate of this embodiment can be obtained by the following procedure.

1. Acquisition steps of void data and inherent void data

First, the amount of fluctuation caused by the position of the adjacent gap of the specific exposure device is grasped. The measurement of the proximity gap can be performed by attaching the sample mask substrate to the mask holding portion of the exposure device, placing the sample glass substrate on the pedestal on which the object to be transferred of the exposure device is placed, and measuring the distance therebetween. That is, at a plurality of positions on the main surface of the sample mask substrate, the distance between the sample mask substrate and the sample glass substrate, that is, the near gap is grasped. Specifically, the close gaps of the plurality of measurement points on the main surface of the sample mask substrate are respectively measured. For example, in a region corresponding to the pattern region in the main surface of the sample mask substrate, a lattice point having a specific interval (for example, a specific value in the range of 10 mm to 300 mm) is set, and each grid point can be used as a measurement point. The distance between the lattice points is preferably selected, for example, in the range of 50 mm to 250 mm.

The pattern area may be, for example, an area other than the area within 50 mm of the four sides of the outer edge of the sample mask substrate.

The measurement of the proximity gap can be performed, for example, by irradiating light obliquely above (or below) the sample mask substrate, and detecting reflected light from the mask pattern surface (main surface) of the sample mask substrate and reflected light from the glass substrate. Alternatively, as described in Patent No. 3,954,841, a measurement method using reflection of a glass plate constituting an airtight chamber can also be applied.

Here, a case where an apparatus for holding the both sides and holding the lower surface is provided, and a device for pressing the bending suppressing mechanism on the outer side of the holding member is provided as an example will be described.

In the measurement of the proximity gap, it is preferable to use a bending suppressing mechanism provided in the exposure apparatus. For example, the optimum conditions obtained by the simulation shown in Fig. 3 above (the condition that the bending is substantially zero) are applied, and the measurement of the close gap is preferable.

The adjacent gaps of the measurement points thus obtained are different (deviation) depending on the position, and thus indicate the change in the position of the proximal gap. The data of the adjacent gaps having such deviations is taken as the void data A.

In addition, the void data A obtained above actually means the flatness of the sample mask substrate (the pattern surface, the pattern surface and the back surface in the case where the upper surface is held) or the flatness of the sample glass substrate (the transferred surface and the back surface thereof) ) The adjacent gaps of the influence. However, for the purpose of the present embodiment, it is preferable to obtain void data which does not include variations other than the near-space variation inherent to the exposure apparatus.

The fluctuation inherent in the exposure apparatus caused by the positional change of the proximity gap is a change in reproducibility in a specific exposure apparatus, and includes the following (1) to (3).

(1) The variation of the gap caused by the bending of the reticle itself when the reticle substrate is mounted on the exposure apparatus

(2) The change in the gap caused by the mechanism (the shape of the holding portion, the contact area, etc.) of the holding mask or the manner of the bending suppressing mechanism (pressing position, pressure)

(3) The void variation caused by the unevenness of the flatness of the pedestal on which the transfer target (glass substrate) is placed in the exposure apparatus.

On the other hand, the fluctuations other than the variations inherent in the exposure apparatus include the following (4) and (5).

(4) Void fluctuation due to unevenness in flatness of the pattern surface of the photomask substrate (in the case of holding from the upper surface, void variation due to unevenness in flatness of the back surface)

(5) Void fluctuation due to unevenness in flatness of the transfer surface of the transfer target (glass substrate) placed on the pedestal of the exposure apparatus and the back surface thereof

In the present embodiment, an object of the present invention is to provide a method for effectively taking measures against the variation of the gap which is reproducible within a range in which a specific exposure apparatus is used and which can calculate a quantitative correction amount. Therefore, the measurement of the close gap based on the calculation of the correction amount should be performed using a sample mask substrate which is ideal for flatness without unevenness, and a sample glass substrate which is ideally constructed. Therefore, the sample mask substrate and the sample glass substrate which are close to the above ideal state should be prepared for analysis.

Further, in the case where it is difficult to obtain such an ideal substrate, it is only necessary to carry out the following. That is, it is preferable to obtain data on the inherent variation of the exposure apparatus based on the above-described void data A. That is, in addition to the inherent changes in the exposure apparatus The component of the change is preferably removed. Therefore, first, the void variation component depending on the flatness of the sample glass substrate to be used is first removed from the void data A.

Specifically, a plurality of sample glass substrates are prepared, and the close gaps are sequentially measured, and the individual differences of the sample glass substrates are eliminated by averaging the values of the respective measurement points using the respective void data A. Thereby, the close gap variation (the above (5)) due to the sample glass substrate can be removed. This is the sample data shown in Figure 4(a) (this is used as the void data B).

Next, the void-changing component resulting from the flat surface of the pattern of the sample glass substrate is removed. Here, the flatness of the pattern surface of the sample mask substrate is measured separately, and the corresponding flatness data can be subtracted from the void data B shown in FIG. 4(a) for each corresponding measurement point (FIG. 4(b) Shown).

For the measurement device used for the flatness measurement, for example, a flatness measuring machine manufactured by Kuroda Seiko Co., Ltd., or a Japanese Patent Publication No. 2007-46946 can be used. Specifically, in the same manner as the measurement of the proximity gap described above, a plurality of lattice points are provided on the pattern surface of the sample mask at a specific interval, and the lattice point is used as a measurement point for flatness measurement. Then, when the reference plane substantially parallel to the main surface of the sample mask substrate is determined, the height information of each measurement point with respect to the reference surface is obtained, and this can be used as the flatness data. In the measurement of the flatness, it is preferable to measure the substrate perpendicular to the object as far as possible without being affected by gravity.

Therefore, the gap data C shown in FIG. 4(c) obtained by subtracting the flatness data shown in FIG. 4(b) from the sample data B shown in FIG. 4(a) is a change in the near-space gap which is inherent to the exposure apparatus. Information (referred to as inherent void data).

Further, other methods may be used for the removal of the variable components of the above (4) and (5). For example, in (4), a plurality of sample mask substrates are prepared, and the above-mentioned (4) of the sample mask used can be removed by averaging the values of each of the measurement points using the respective sample data A.

(5), the flatness is measured in advance on the two main surfaces of the sample glass substrate, and the flatness data of each of the obtained measurement points is subtracted from the value of each measurement point corresponding to the reference void data B (actual It is sufficient to determine the difference between the flatness data of each measurement point corresponding to the two main surfaces, that is, the flatness data.

As described above, the obtained inherent void data indicates the change in the void caused by the position inherent to the exposure apparatus to be used. Therefore, the shape of the mask substrate according to the present embodiment is determined based on this.

2. Acquisition steps of shape processing data

The inherent void data obtained above indicates the variation in the voids caused by the exposure device when the ideal flat mask substrate and the ideal flat glass substrate are placed on the exposure apparatus. Therefore, in order to prevent the gap from being changed, if the pattern surface of the mask substrate is subjected to the shape inversion of the variation in advance, the gap variation can be made substantially zero. This state is shown in Fig. 4(d). Fig. 4(d) shows the shape processing data for forming the pattern surface of the inverted shape based on the void variation shown in Fig. 4(c). In addition, in FIG. 4(d), the mask substrate is inverted, and the surface shape of the mask substrate corrected to compensate for the gap variation shown in FIG. 4(c) is observed from the side of the pattern surface, so that the corresponding position is obtained. Move to the left and right symmetrical position.

Figure 4(d) shows the variation of the void based on Figure 4(c) to form the inverse Shape processing data of the shape of the shape of the shape. In other words, a mask substrate having the pattern surface shape shown in FIG. 4(d) is prepared, and when the mask is produced based on this, the actual exposure apparatus will remain substantially free of voids. This is shown in Fig. 4(e).

The above description will be made in a side view using FIG.

Fig. 5(a) shows a state in which a mask substrate having a desired flatness and a panel substrate having a desired flatness are placed on a real exposure apparatus, and a state in which the close gap is changed in accordance with the in-plane position is shown. That is, the distance between the mask substrate and the panel substrate is the largest, and the gap value is maximized (Fig. 5(b)). This corresponds to the aforementioned inherent void data (void data C).

The variation range of the gap (the difference between the maximum and the minimum of the gap) varies depending on the actual exposure apparatus, but is generally in the range of 20 to 70 μm. For example, in the case of an exposure apparatus having a variation width of 50 μm, the portion of the 50 μm portion can be offset by the shape of the pattern surface of the mask substrate. The surface shape of the mask substrate at this time is shown in Fig. 5(c). In FIG. 5(c), when the curved line is a pattern surface, the upper side becomes the space side and the lower side becomes the mask substrate side.

From the viewpoint of transfer accuracy, the variation in voids is extremely small. However, in the proximity exposure, the extent to which the variation of the void caused by the position in the plane is allowed is different depending on the use or specification of the desired product, and therefore the variation allowable value is set according to the target accuracy. The reason for this is that in the shape processing of the photomask substrate for causing the void variation to be zero, the removal amount of the removal processing (polishing or the like) is increased, or the shape requiring difficulty in processing is required, and the actual production efficiency and yield are points. Not necessarily beneficial.

On the other hand, in the case where the in-plane uniformity of the adjacent gap is sought to be described below, the case where the allowable value of the void variation corresponding to the applicable product or specification is considered. For example, in the product to be obtained, the maximum allowable void variation value (hereinafter referred to as the variation allowable value T (μm)) can be set to a specific value between 40 and 10 (μm). In other words, according to the accuracy of the liquid crystal display device to be obtained, the extremely high precision is 10 μm, the slightly smaller specification is 40 μm, and the middle can be appropriately set to 20 μm or 30 μm.

Fig. 6 is a view showing the step of determining the corrected shape of the mask substrate by displaying the value of the gap data C application variation tolerance value T.

Fig. 6(a) determines the corrected shape based on the maximum value (the gap is the largest) of the void data C. In other words, when the position P of the maximum gap is compared with the upper limit of the allowable value T of the pattern surface after the shape processing, the portion where the variation allowable value T cannot be satisfied by the shape machining correction (the portion where the void exceeds the allowable range becomes smaller). 6(a) slash part). In other words, when the height of the position P which becomes the maximum gap is Z1, the portion which is lower than (Z1-T) is subjected to, for example, the shape processing for removing at least the portion. This method is used as the maximum reference method.

In addition, the height referred to herein is the distance from the vertical direction of the main surface of the reticle (when a desired main surface is assumed), and is considered to be relative to the height of the ideal main surface.

For example, when the maximum value reference method is employed, a concave shape indicated by a broken line in FIG. 6(b) may be formed on the pattern surface of the mask substrate. Further, since the concave portion is corrected by the portion where the gap is too small, it is necessary to perform the removal processing until the broken line shape, but it is also possible to continue the removal processing beyond the above, and to allow the removal processing up to the solid line. That is, between the dotted line and the solid line, it can be said The processing tolerance is removed. Then, the area to be processed between the two becomes a specific area as described in the present invention. Further, according to the maximum reference method, the shape of the mask substrate material is processed to form a concave shape.

In Fig. 6(b), the corrected shape is determined based on the center value of the maximum value and the minimum value with respect to the gap data C. In other words, the shape of the gap is more than 2/T with respect to the gap center value, and the gap is larger than 2/T. In other words, if the height of the position where the near gap indicates the central value is Z2, the portion where the height on the main surface exceeds (Z2+T/2) and the portion lower than (Z2-T/2) are respectively specified. This part is specified and shape processed. Use this method as a central benchmark.

According to the center reference method, as shown in FIG. 6(d), the removal processing may be performed by a broken line, and the allowable range of the removal processing may be allowed between the broken line and the solid line.

Further, in Fig. 6(c), the corrected shape is determined based on the minimum value (the minimum of the gap) with respect to the gap data C. In other words, when the position B of the minimum gap is compared with the lower limit of the allowable value T of the pattern surface after the shape processing, the portion where the variation allowable value T cannot be satisfied by the shape machining correction (the portion where the gap exceeds the allowable range becomes larger, FIG. 6 (e) the slash part). That is, when the height of the position B which is the minimum gap is Z3, the portion which is higher than (Z3+T) is processed, and the shape in which at least the remaining portion is removed is processed. Use this method as the minimum benchmark.

If the minimum reference method is used, it is only necessary to have a corrected shape as shown in Fig. 6(c). Specifically, as long as the convex shape indicated by the broken line is formed on the pattern surface, and as an allowable range, the area between the dotted line and the solid line is allowed. area.

In the center value reference method or the minimum value reference method, the area to be processed becomes a specific area between the broken line and the solid line in FIGS. 6(d) and (f).

According to any of the above three methods, the corrected shape is different. Therefore, the most appropriate way can be selected depending on the device or step used in the processing.

For example, according to the maximum reference method, the amount of removal (workload) from the substantially flat mask substrate material can be reduced, which is preferable. Further, when the removal processing is performed as a polishing process and the concave shape is formed on the surface, the removal amount is locally increased by increasing the polishing load of the portion. In the case of using such a method, the efficiency of locally forming the concave portion is better than the partial formation of the convex portion (the periphery of the position where the convex portion is removed), and therefore the maximum reference method is advantageous.

The above investigation was made to determine the corrected shape when the variation allowable value T was applied. Figures 4(f) to (n) show them in plan view.

4(c) to (e), the variation allowable value T is zero, and the correction shape of the void variation when the shape-processed mask substrate is used is determined, and FIG. 4(f) to (h) This shows the case where the shape determination is performed in the maximum reference mode. At this time, instead of directly using the void data shown in FIG. 4(c), the mask substrate having the surface shape reversed is formed, and the maximum position of FIG. 4(c) is used as a reference, and only the unsatisfied The part of the variation allowable value (here, 35 μm) is the object of shape processing. As can be seen from Fig. 4(g), the shape processing may be a concave shape. Further, as is clear from Fig. 4(h), the void variation remains after the shape processing, but the fluctuation range is 35 μm or less of the variation allowable value T.

Similarly, Figures 4(i)~(k) show the shape plus the central reference method. Changes in voids remaining after work data and shape processing. Further, Fig. 4 (l) to (n) show the same data when the minimum value reference method is used.

3. Steps of shape processing on the mask substrate

In general, the photomask substrate can be prepared by preparing a glass substrate material for a photomask and planarizing the two main surfaces by polishing. For example, a glass substrate material having a flatness of 5 to 30 μm on the back side of the pattern surface and the pattern surface can be used. The glass substrate material thus obtained is used as a material of the mask substrate, and further processed into a shape to obtain a mask substrate of the present embodiment.

The shape of the processing is determined according to the above method. For example, the shape processing data shown in Fig. 4(g) can be used to perform shape processing using a well-known processing apparatus.

For example, a shape processing can be performed using a polishing apparatus having a polishing flat plate that is rotatable, a polishing pad provided on the polishing flat plate, and an abrasive supply mechanism that supplies an abrasive to the surface of the polishing pad. When the glass substrate material is held on the polishing pad and the concave portion is to be formed by shape correction, the pressure of the polishing pad to the substrate is increased as compared with other regions, and the glass substrate material can be polished on one side. When pressing, it is preferable to have a device having a plurality of pressurizing bodies, and a control mechanism capable of independently performing pressure pressurization control on each of the pressurizing bodies. In the case where the convex portion is formed, the peripheral region of the convex portion can be subjected to pressure control in a larger removal amount.

Or it can be processed using a shape of a vertical milling machine. A polishing cup head to which a polishing cloth is adhered may be attached to the processing portion of the apparatus, and the polishing liquid may be supplied while being processed while controlling the height direction.

Further, in the polishing step, the glass substrate material subjected to the rough polishing and the precision polishing may be subjected to the above-described shape processing, or the rough processing may be performed after the rough processing, and the shape processing reflecting the shape processing data may be performed.

The kind or particle diameter of the abrasive to be used can be appropriately selected depending on the substrate material or the desired flatness. Examples of the polishing agent include cerium oxide, zirconium oxide, colloidal silica, and the like. The particle size of the abrasive may be several tens of nm to several μm.

4. Composition of the mask substrate

The photomask substrate of this embodiment is configured as follows.

In other words, a photomask substrate is formed on a main surface to form a transfer pattern, and is attached to a proximity exposure device, and is provided with a close gap between the transfer target placed on the pedestal of the proximity exposure device and exposed. For the photomask used for transferring the transfer pattern, One or a plurality of specific regions on the main surface are subjected to shape processing different from the peripheral region outside the specific region to form a concave shape, a convex shape, or a concave-convex shape, thereby reducing the mounting of the mask substrate The change caused by the position of the aforementioned close gap generated when the exposure device is close to the exposure device, The shape processing system is inherently variable in the exposure apparatus that reduces fluctuations in the position caused by the proximity gap.

The above-mentioned concave shape, convex shape, or uneven shape means a shape when the above-mentioned mask substrate is excluded from the influence of gravity. Further, the peripheral region is a peripheral region adjacent to the specific region on the outer side of the specific region. The specific area is any area on the main surface of the reticle substrate, and is shaped into a shape The area of the object. The shape processing region shown by the broken line or the solid line in the above-mentioned Figs. 6(b), (d), and (f) can be obtained. The specific area is set to one or plural on the main surface. In the case where a plurality of sheets are set, the types of the convex shape, the concave shape, the uneven shape, or a combination thereof are not restricted.

As the processing method, for example, a removal process of removing a surface portion by grinding or the like can be applied. In addition to grinding, methods such as sandblasting can also be applied. The removal amount different from the peripheral region means that the shape is processed as a deeper removal or a shallower removal than the periphery. A portion having a height relatively higher or lower than other regions can be formed by increasing or decreasing the amount of removal (for example, the amount of polishing). Or by removing only a specific area of processing, the height is relatively lower than the other areas.

Further, the shape processing may be performed such that the gap inherent in the exposure apparatus fluctuates within the allowable range of the product (the variation allowable value T or less). The variation allowable value T is determined based on the use or specification of a device to be manufactured using the photomask of the embodiment. Therefore, the proximity gap variation formed when the mask substrate of the present embodiment is attached to the exposure apparatus is equal to or less than the gap variation allowable value T of the ideal glass substrate.

Further, in the present invention, when the region other than the region within 50 mm from the four sides of the outer surface of the main surface of the mask substrate is used as the pattern region, it is preferable to carry out the above-described shape processing in the pattern region. On the other hand, in the region within 50 mm from the four sides (outside the pattern region), the above-described shape processing may not be performed, and the following points are advantageous.

When the photomask substrate is mounted on the above-mentioned two-side holding and the lower surface is held by the exposure apparatus, the photomask substrate is opposite to the two sides of the pattern surface. (When the pattern surface of the mask substrate is rectangular, it is preferably relatively long. Side) within 50 mm Since the area is the holding area where the holding member of the exposure device contacts, the flatness of the surface of the mask substrate is preferably high.

For example, when the difference between the two points of the distance Pmm (5 ≦ P ≦ 15) in the region is Z μm, Z/P is preferably 0.08 or less.

Further, when the photomask substrate of the present invention is used in the case where the photomask substrate is mounted on the four sides and the lower surface is held by the exposure device, the contact member is kept in contact with the holding member of the exposure device within 50 mm from the four sides of the pattern surface. Therefore, the flatness of the surface of the mask substrate is preferably high, and the above-described Z/P is preferably 0.08 or less.

Further, in consideration of the case where the photomask substrate of the present invention is mounted on the four-side holding and the upper surface is held by the exposure apparatus, the area in which the distance from the four sides of the pattern surface is within 50 mm is maintained by the contact of the holding member of the exposure apparatus. Therefore, the flatness of the surface of the reticle substrate is preferably high, and the same Z/P in the region is preferably 0.08 or less.

The flatness measuring method can be the same as that described for the flatness measurement of the sample mask substrate.

5. Steps for manufacturing a photomask

The use of the photomask substrate of the present embodiment is not particularly limited. For example, it can be applied to a photomask of the kind exemplified below. In particular, when used in a photomask for manufacturing a liquid crystal display device, a photomask used for the production of a CF (color filter) or a TFT (thin film) substrate, the effects of the present invention can be remarkably obtained.

For example, a light-shielding film as an optical film is formed on the main surface of the photomask substrate obtained by the above steps, whereby a binary mask blank for photomask manufacturing can be obtained. As a light-shielding film, chromium can be used. (chromium) or chromium containing a film selected from a chromium compound of at least one of oxygen, nitrogen, and carbon, or containing a film selected from the group consisting of silicon, tantalum, molybdenum, and tungsten (tungsten). A metal such as a metal element, a metal oxide, a metal nitride, a metal oxynitride, a metal oxycarbide, a metal carbide carbide, or a metal oxynitride carbide.

Alternatively, as the optical film, a semi-transmissive film that transmits a part of the exposure light during exposure may be used. A plurality of films may also be laminated. The material of the semi-transmissive film can also be selected from the same material as the above-mentioned light-shielding film, and can be used by adjusting the light transmittance for exposure to 5 to 80% by combining and film thickness.

Further, a multi-tone mask can be obtained by patterning using the above-described light shielding film or semi-transmissive film as appropriate. A multi-step dimming cover having a light-shielding portion for light-shielding exposure, a portion of a semi-transmissive portion for transmitting light for exposure, and a light-transmissive portion for substantially transmitting the light for exposure, which has a transfer pattern, can be obtained. . In this case, the resist pattern formed on the transfer target is processed into a three-dimensional shape mask in which the amount of residual film (height) differs depending on the position, and it is obtained by using one mask on the transfer target twice. The mask of the above patterned effect. For example, it can be advantageously used for the manufacture of a color filter having a plurality of photo spacers having different heights.

As a film forming method of the above optical film, a known method such as a sputtering method or a vacuum vapor deposition method can be applied.

In the manufacturing steps of the photomask, a well-known photolithography method can be applied. The optical film was formed on the main surface (pattern surface) of the photomask substrate obtained by the above procedure as many times as necessary, and a resist was further applied to produce a photomask substrate. Then, use a laser or electron The beam drawing device draws a pattern on the resist film. Then, the drawn resist film is developed, and the formed resist pattern is used as a mask, wet etching or dry etching of the optical film, thereby forming a thin film pattern. The above-described photolithography process is repeated as many times as necessary to manufacture a photomask having a desired transfer pattern.

6. Steps for pattern transfer

The exposure device can use a well-known proximity contact user. As the exposure light source, a light source including a wavelength range of an i line, an h line, and a g line can be used.

The photomask obtained by the photomask substrate of the present embodiment is a photomask used for attachment to an exposure apparatus used for measurement of the proximity gap. The substrate holding mechanism for the exposure device for holding the photomask substrate is not particularly limited under the same conditions as those for the measurement for the proximity gap. It can also be applied to any of the above-described two-side holding, four-side holding or lower surface holding, and upper surface holding. In the case where the gap is measured, when the bending suppressing mechanism or the like is acted upon, the same effect is applied to the pattern transfer and exposure.

When the mask substrate of the present embodiment is mounted on the exposure apparatus, it is attached in consideration of the orientation of the mask substrate determined during the shape processing. That is, the measurement of the proximity gap and the pattern transfer are performed so that the orientation of the mask substrate coincides.

Further, depending on the application method of the gap variation allowable range (variation allowable value T), the correction shape of the mask substrate is different. That is, according to the concave shape processing or the convex shape processing of the mask substrate, the setting values of the close gaps set in the exposure apparatus at the time of pattern transfer are different.

According to this embodiment, the variation of the close gap can be suppressed to a specific range. Therefore, the set value of the close gap can be reduced by itself. In other words, the distance between the pattern surface of the photomask and the resist film surface of the transfer target can be set small, and the resolution can be improved. For example, the setting value of the close gap set in the exposure apparatus at the time of pattern transfer can be set to 30 to 180 μm.

As described above, according to the present embodiment, it is possible to largely remove the cause of the fluctuation of the proximity gap caused by the exposure machine used. In addition, although the bending due to the weight of the photomask itself is one of the causes of the change in the close gap caused by the structure of the exposure machine used, according to the study of the inventors of the present invention, the exposure apparatus cannot be ignored. In the case of the cause of the change, according to the present embodiment, the fluctuation of the adjacent gap can be effectively suppressed.

The application of the photomask of the present embodiment is not particularly limited. Further, as described above, when used as a photomask for manufacturing a liquid crystal display device, a remarkable effect can be obtained. For example, when the photomask of the present embodiment is used as a TFT substrate manufacturing mask, the proximity gap can be controlled within a specific allowable range, so that the pattern line width or the coordinates can be greatly improved. Further, when used as a mask for CF manufacturing, for example, when a black matrix or a color plate is manufactured, line width accuracy or coordinate accuracy can be greatly improved. Further, when the photosensitive spacer which controls the gap precision between the TFT-CF is manufactured, the shape of the spacer (the shape in the X direction, the Y direction, the height in the Z direction, or the slope shape) can be improved in accuracy. Get a significant effect.

7. Evaluation method for the adjacent gap

As described above, according to the present embodiment, the close gap in the case where the photomask is placed on the exposure apparatus can be accurately and effectively evaluated.

Specifically, the sample mask substrate is mounted on the proximity exposure device, Carrying the sample glass substrate on the pedestal of the proximity exposure device, and determining the gap data indicating the change of the proximity gap caused by the position by measuring the close gap of the plurality of positions of the main surface of the sample mask substrate;

Obtaining, from the gap data, the step of obtaining the inherent void data by taking in the variable components inherent in the proximity exposure device,

By using the above-described inherent void data and the specific gap variation allowable value, by finding the position of the close gap and the excess amount exceeding the variation allowable value, it is possible to accurately and effectively evaluate the close gap when the mask is placed on the exposure apparatus.

<Other Embodiments of the Invention>

The embodiment of the present invention has been specifically described above, but the present invention is not limited to the embodiment described above, and various modifications can be made without departing from the spirit and scope of the invention.

1‧‧‧Photomask

2‧‧‧Photomask holder

1a‧‧‧Photomask Adsorption Road

1b‧‧‧Air attraction road

3‧‧‧Bend correction rod

4‧‧‧Photomask holder

M‧‧‧Photo Mask

SA‧‧‧Intensive room

(a) and (b) of FIG. 1 are schematic views of a bending correction mechanism of an exposure apparatus described in Patent Document 1.

2(a) and 2(b) are schematic diagrams showing a bending correction mechanism of the exposure apparatus described in Patent Document 2.

3(a) and 3(b) are schematic diagrams showing a simulation of correction of the curvature of the mask substrate.

4(a) to 4(n) are schematic diagrams showing the steps of the manufacturing process of the photomask substrate of the embodiment, showing the measurement of the proximity gap and the variation of the gap inherent in the exposure apparatus.

5(a)-(c) show the manufacturing steps of the photomask substrate of the embodiment. A schematic diagram of a step, (a) exemplifies the case where the near gap is generated, (b) exemplifies the void information inherent to the exposure apparatus, and (c) exemplifies the surface shape of the mask substrate formed by offsetting the void data.

6(a) to 6(f) are schematic diagrams showing the steps of determining the correction shape of the mask substrate, which is shown in the tolerance value of the gap data set in the exposure apparatus.

Claims (18)

A photomask substrate characterized in that a transfer pattern is formed on a main surface, and is mounted on a proximity exposure device, and is provided with a close gap between the transfer target placed on the pedestal of the proximity exposure device and exposed. For forming a photomask used for transferring the transfer pattern, one or a plurality of specific regions on the main surface are subjected to shape processing different from the peripheral region outside the specific region. Forming a concave shape, a convex shape, or a concave-convex shape, thereby reducing a positional change caused by the position of the proximity gap generated when the mask substrate is attached to the proximity exposure apparatus, and the shape processing system lowers a position from the proximity gap The change caused by the aforementioned proximity exposure device is taken up by the change. The reticle substrate of claim 1, wherein the main surface subjected to the shape processing has a correction shape determined based on a variation inherent in the proximity exposure device. The photomask substrate according to claim 1, wherein the shape processing is performed only on a specific region on the main surface including a region in which the variation of the proximity exposure device that is extracted exceeds a specific gap variation allowable value. The reticle substrate of claim 1, wherein the shape processing is performed on the main surface to form one or a plurality of recesses. A method of manufacturing a mask substrate, wherein the mask substrate is a photomask having a transfer pattern formed on a main surface thereof, and is attached to a proximity exposure device and mounted on a pedestal of the proximity exposure device Exposing the adjacent transfer gap between the transfer bodies to expose the transfer A photomask used for printing a pattern, wherein the method of manufacturing the mask substrate is to measure a near gap of a plurality of positions on the main surface, and to vary the position of the proximity gap caused by a change in the position of the proximity gap. And determining a correction shape of the main surface of the mask substrate based on the variation of the proximity of the proximity exposure apparatus and the specific tolerance of the gap change, and performing the correction as determined above on the main surface of the mask substrate Shape shape processing. A method of manufacturing a mask substrate, wherein the mask substrate is a photomask having a transfer pattern formed on a main surface thereof, and is attached to a proximity exposure device and mounted on a pedestal of the proximity exposure device The light-receiver used for transferring the transfer pattern is formed by providing a close gap between the transfer bodies, and the method for manufacturing the mask substrate includes the steps of: mounting the sample mask substrate on the sample mask substrate In the proximity exposure device, the sample glass substrate is placed on the pedestal of the proximity exposure device, and by measuring the close gap of the plurality of positions on the main surface of the sample mask substrate, the proximity gap caused by the position is obtained. Varying void data; obtaining the inherent void data from the gap data by using the inherent variation component of the proximity exposure apparatus; and obtaining the shape processing data for the mask substrate by using the inherent void volume data and the specific gap variation allowable value; And using the aforementioned shape processing data to enter the main surface of the reticle substrate Line shape processing. The method of manufacturing a photomask substrate according to claim 6, wherein in the step of obtaining the intrinsic void material, the component of the adjacent gap of the plurality of positions is removed by a component of the adjacent mask gap of the sample mask substrate. The method of manufacturing a photomask substrate according to claim 6, wherein in the step of obtaining the intrinsic void data, the component of the adjacent space of the plurality of positions is removed by a component of the adjacent glass gap of the sample glass substrate. The method of manufacturing a photomask substrate according to claim 6, wherein in the measurement of the proximity gap, the bending suppression mechanism provided in the proximity exposure apparatus is used to suppress bending due to the weight of the sample mask substrate. The method of manufacturing a photomask substrate according to claim 6, wherein in the step of obtaining the shape processing data, the gap between the adjacent gaps caused by the position of the proximity exposure device indicated by the inherent gap data is greater than the gap variation tolerance Part of the value, and shape processing is performed on a specific region including the aforementioned specific portion. The method of manufacturing a photomask substrate according to claim 6, wherein the height of the main surface at a position where the near gap is at a maximum value is Z1, and when the allowable value of the gap variation is T, the main surface is specified. The upper portion is lower than the portion (Z1-T), and the specific region including the aforementioned specific portion is subjected to shape processing. The method of manufacturing a photomask substrate according to any one of claims 5 to 11, wherein the shape processing is performed by forming one or a plurality of recesses on a main surface of the photomask substrate. A reticle substrate obtained by forming an optical film for forming the transfer pattern, on a main surface of a reticle substrate according to any one of claims 1 to 4. A photomask obtained by patterning an optical film formed on a main surface of a photomask base of claim 13 by photolithography to form the transfer pattern. The reticle of claim 14 is for use in the manufacture of a liquid crystal display device. A pattern transfer method, characterized in that a transfer pattern formed on the photomask is formed by attaching a photomask as claimed in claim 15 to the proximity exposure device used for measurement of the proximity gap Transfer onto the transfer target. A method of manufacturing a liquid crystal display device characterized by using a pattern transfer method as claimed in claim 16. A method for evaluating a proximity gap, which is a method for evaluating a proximity gap of a proximity exposure device, comprising the steps of: mounting a sample mask substrate on the proximity exposure device, and placing a sample glass substrate on a pedestal of the proximity exposure device; The gap data indicating the change of the adjacent gap caused by the position is obtained by measuring the close gap of the plurality of positions of the main surface of the sample mask substrate; and the variation component inherent to the proximity exposure device is obtained from the gap data. The inherent void data; and the use of the inherent void data and the specific allowable value of the void variation, and the position of the close gap generation exceeding the allowable variation value and the excess amount thereof are obtained.