JP5497693B2 - Photomask substrate, photomask substrate manufacturing method, photomask manufacturing method, and pattern transfer method - Google Patents

Description

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

  Patent Document 1 discloses a two-sided side of a photomask as a deflection correction mechanism for reducing the deflection due to the weight of the photomask in a proximity exposure apparatus that exposes a photomask and an object to be transferred in close proximity. Each having a mask holder and two deflection correction bars that press the edges on both sides of the photomask held by the mask holder from above (FIGS. 1A and 1B). )reference).

  Patent Document 2 describes a mask holding device that corrects deflection of a photomask in a proximity exposure apparatus. Here, the mask is held by a frame-shaped mask holder that is approximately the same size as the mask, and an airtight chamber is formed above the photomask so that the weight of the photomask is balanced by the difference between the air pressure in the airtight chamber and the external pressure. Describes a method of correcting deflection by floating a photomask (see FIG. 2).

  In Patent Document 3, such a problem that the desired flatness cannot be obtained because the substrate is bent during actual use in which a large-sized photomask substrate is held horizontally in an exposure apparatus. A glass substrate for flattening the substrate is described.

JP 2009-260172 A JP 2003-131388 A Japanese Patent No. 4362732

  Recently, in the manufacture of a display device such as a liquid crystal display device, a high transfer accuracy is required along with an improvement in production efficiency due to an increase in the size of a photomask to be 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 bonded together, and liquid crystal is sealed therebetween. Such a TFT substrate and CF are manufactured by applying a photolithography process using a plurality of photomasks. In recent years, with the advancement of specifications such as the brightness and operation speed of the liquid crystal display device, which is the final product, the pattern of photomasks has become finer, and the requirements for line width accuracy and coordinate accuracy as a transfer result have become increasingly severe. Yes.

  Therefore, the present invention provides a photomask substrate capable of accurately transferring even a miniaturized transfer pattern faithfully to the pattern design value, and a photomask blank and photomask manufacturing method using the photomask substrate An object of the present invention is to propose a pattern transfer method using the same.

The first aspect of the present invention is:
A transfer pattern is formed on the main surface, mounted on a proximity exposure apparatus, exposed with a proximity gap between the transfer object placed on the stage of the proximity exposure apparatus, and the transfer pattern A photomask substrate for forming a photomask used to transfer
The photomask is formed by forming a concave shape, a convex shape, or a concavo-convex shape in one or a plurality of specific regions on the main surface by performing shape processing with a different removal amount from the peripheral region outside the specific region. Variation due to the position of the proximity gap that occurs when the substrate is mounted on the proximity exposure apparatus is reduced; and
The shape processing is a photomask substrate that reduces variations inherent in the proximity exposure apparatus extracted from variations due to the position of the proximity gap.

The second aspect of the present invention is:
The main surface on which the shape processing has been performed is the photomask substrate according to the first aspect having a corrected shape determined based on a variation inherent in the extracted proximity exposure apparatus.

The third aspect of the present invention is:
The shape processing is performed only on a specific region on the main surface including a region where the inherent variation of the extracted proximity exposure apparatus exceeds a predetermined gap variation allowable value. A photomask substrate according to the first or second aspect.

The fourth aspect of the present invention is:
The shape processing is the photomask substrate according to any one of the first to third aspects, in which one or a plurality of recesses are formed on the main surface.

According to a fifth aspect of the present invention,
A photomask having a transfer pattern formed on the main surface, mounted on a proximity exposure apparatus, and exposed by providing a proximity gap between the transfer object placed on the stage of the proximity exposure apparatus And a photomask substrate manufacturing method for forming a photomask used for transferring the transfer pattern,
Measuring proximity gaps at multiple locations on the main surface;
Among variations due to the proximity gap position, extract variations inherent to the proximity exposure apparatus,
And variation inherent to the extracted the proximity exposure apparatus, on the basis of the predetermined gap variation tolerance, to determine the correct shape of the main table surface of the photomask substrate,
Primary table surface of the photomask substrate, a manufacturing method of a photomask substrate subjected to shaping so as to with the determined correction shape.

The sixth aspect of the present invention is:
A photomask having a transfer pattern formed on the main surface, mounted on a proximity exposure apparatus, and exposed by providing a proximity gap between the transfer object placed on the stage of the proximity exposure apparatus And a photomask substrate manufacturing method for forming a photomask used for transferring the transfer pattern,
By mounting the sample mask substrate on the proximity exposure apparatus, placing the sample glass substrate on the stage of the proximity exposure apparatus, and measuring the proximity gap at a plurality of positions on the main surface of the sample mask substrate, Obtaining gap data indicating a change in proximity gap due to
Extracting a fluctuation component specific to the proximity exposure apparatus from the gap data to obtain specific gap data;
Obtaining shape processing data to be applied to the photomask substrate using the inherent gap data and a predetermined gap variation allowable value;
And a step of performing shape processing on the main surface of the photomask substrate using the shape processing data.

The seventh aspect of the present invention is
The method of manufacturing a photomask substrate according to the sixth aspect, wherein, in the step of obtaining the inherent gap data, a component of the proximity gap variation caused by the sample mask substrate is removed from the variation of the proximity gap at the plurality of positions. It is.

The eighth aspect of the present invention is
The photomask substrate according to the sixth or seventh aspect, wherein in the step of obtaining the inherent gap data, a component of the proximity gap variation caused by the sample glass substrate is removed from the variation of the proximity gap at the plurality of positions. It is a manufacturing method.

The ninth aspect of the present invention provides
In the measurement of the proximity gap, the photomask substrate manufacturing method according to any one of the sixth to eighth aspects, in which a deflection suppressing unit included in the proximity exposure apparatus is used to suppress the deflection due to the weight of the sample mask substrate. Is the method.

The tenth aspect of the present invention provides
In the step of obtaining the shape processing data, a portion of the proximity gap fluctuation indicated by the unique gap data and having a position unique to the proximity exposure apparatus that exceeds the gap fluctuation tolerance is specified, and the specified part is specified. It is a manufacturing method of the photomask substrate as described in any one of the 6th-9th aspect which shape-processes with respect to the specific area | region containing this.

The eleventh aspect of the present invention is
Of the inherent gap data, when the height of the main surface at the position where the proximity gap is the maximum value is Z1, and the gap variation allowable value is T, the height on the main surface is (Z1-T The method for manufacturing a photomask substrate according to any one of the sixth to tenth aspects, wherein a lower part is specified and shape processing is performed on a specific region including the specified part.

The twelfth aspect of the present invention provides
The shape processing is the method for manufacturing a photomask substrate according to any one of the fifth to eleventh aspects, in which one or a plurality of recesses are formed on the main surface of the photomask substrate.

The thirteenth aspect of the present invention provides
Optical thin film for forming the transfer pattern on the main surface of the photomask substrate according to any one of the first to fourth aspects or the photomask substrate according to the manufacturing method according to any one of the fifth to twelfth aspects Is a photomask blank formed.

The fourteenth aspect of the present invention provides
A photomask in which the transfer pattern is formed by patterning an optical thin film formed on the main surface of the photomask blank according to the thirteenth aspect by a photolithography method.

The fifteenth aspect of the present invention provides
The photomask according to the fourteenth aspect, which is used for manufacturing a liquid crystal display device.

The sixteenth aspect of the present invention provides
The photomask according to the fifteenth aspect is mounted on the proximity exposure apparatus used for the measurement of the proximity gap and exposed to expose a transfer pattern formed on the photomask on the transfer target. This is a pattern transfer method for transferring.

The seventeenth aspect of the present invention provides
A liquid crystal display manufacturing method using the pattern transfer method according to the sixteenth aspect.

The eighteenth aspect of the present invention provides
In the proximity gap evaluation method of the proximity exposure apparatus,
By mounting the sample mask substrate on the proximity exposure apparatus, placing the sample glass substrate on the stage of the proximity exposure apparatus, and measuring the proximity gap at a plurality of positions on the main surface of the sample mask substrate, Obtaining gap data indicating a change in proximity gap due to
Extracting a fluctuation component specific to the proximity exposure apparatus from the gap data to obtain specific gap data;
This is a proximity gap evaluation method that uses the unique gap data and a predetermined gap fluctuation allowable value to obtain a position where a proximity gap exceeding the fluctuation allowable value occurs and the excess amount.

  According to the present invention, when transferring a transfer pattern of a photomask to a transfer object using proximity exposure, the proximity gap is controlled within a certain numerical range to improve transfer accuracy. be able to. In particular, the fluctuation of the proximity gap depending on the exposure apparatus to be used can be greatly reduced.

It is the schematic explaining the bending correction mechanism of the exposure apparatus described in patent document 1. FIG. It is the schematic explaining the bending correction mechanism of the exposure apparatus described in patent document 2. FIG. It is the schematic which shows the simulation of correction | amendment with respect to the bending of a photomask board | substrate. It is the schematic which shows 1 process of the manufacturing process of the photomask substrate which concerns on this embodiment, and shows a mode that the gap fluctuation peculiar to the measurement of a proximity gap and exposure apparatus is grasped | ascertained. It is the schematic which shows 1 process of the manufacturing process of the photomask substrate which concerns on this embodiment, (a) is a mode that a proximity gap arises, (b) is gap data peculiar to exposure apparatus, (c) is a gap. Each of the surface shapes of the photomask substrate formed so as to cancel the data is illustrated. It is the schematic which shows the process of applying the fluctuation tolerance to gap data intrinsic | native to an exposure apparatus, and determining the correction | amendment shape of a photomask substrate.

(Importance of uniform proximity gap)
In manufacturing the TFT substrate or CF, a pattern transfer method employing proximity exposure is advantageously used. In proximity exposure, a transfer target (hereinafter also referred to as a glass substrate) on which a resist film is formed and the pattern surface of the photomask are held facing each other, the pattern surface faces downward, and the back surface of the photomask (pattern The pattern is transferred to the resist film by irradiating light from the side opposite to the formation surface. At this time, a predetermined minute gap (proximity gap) is provided between the photomask and the transfer body. The proximity gap can be, for example, about 30 to 300 μm, more preferably about 50 to 180 μm. The photomask includes a transfer pattern in which predetermined patterning is performed on an optical film (such as a light-shielding film or a semi-transparent film that partially transmits exposure light) formed on the main surface of the transparent substrate. . The main surface on which this transfer pattern is formed becomes the pattern surface.

  According to the proximity exposure method, if the proximity gap is maintained uniformly over the entire pattern surface, pattern transfer can be performed with high transfer accuracy, and if there is a guarantee that the proximity gap is maintained uniformly, By setting the proximity gap to be small, a transfer pattern with higher resolution can be obtained, and therefore, the importance of controlling in-plane variation of the proximity gap (that is, proximity gap fluctuation depending on the position) is increasing. However, it is not easy to maintain this proximity gap uniformly 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 main surface has, for example, a long side L1 of 600 to 1400 mm and a short side L2 of 500 to 500 mm. 1300 mm and thickness T can be about 5 to 13 mm. With the trend toward larger photomasks and increased weight, it has become increasingly important to suppress fluctuations in the proximity gap during transfer.

(Retention system for exposure equipment)
In the proximity exposure apparatus, there are a plurality of methods for mounting (holding in the apparatus) a photomask.

  In general, when a photomask is mounted on a proximity exposure apparatus, the outside of a pattern surface in which a transfer pattern is formed (also referred to as a pattern area) is held by a holding member of the exposure apparatus. For example, in the apparatus described in Patent Document 1 shown in FIG. 1, when the regions near the two opposite sides of the rectangular main surface of the photomask 1 are used as holding regions (two-side holding), this holding region Further, the mask holder 2 which is a holding member of the exposure apparatus abuts from below (holding the lower surface), and the photomask can be held. The contact surface between the photomask and the holding member may be adsorbed as a reduced pressure (see Japanese Patent Application Laid-Open No. 2010-2571), or may be contacted by a tangent line as shown in FIG. In the case of such lower surface holding, the photomask is held from below by two holding members, so that the photomask is arranged in the exposure apparatus in a substantially horizontal posture while maintaining a predetermined proximity gap with the glass substrate. Alternatively, the vicinity of the four sides of the main surface can be held from below (holding four sides).

  Further, for example, in the apparatus described in Patent Document 2 shown in FIG. 2, the outer side of the pattern region of the photomask M and the back surface (the surface opposite to the pattern surface) is used as a holding region, and a holding member is used here. The photomask M can be supported from the upper surface side by bringing a certain mask holder 1 into contact (holding the upper surface) and sucking and sucking these contact surfaces through the mask suction path 1a.

(Exposure device deflection suppression means and its effects)
It is known from Documents 1 to 3 that when a photomask substrate is mounted on a proximity exposure apparatus (hereinafter also simply referred to as an exposure apparatus), the photomask substrate is bent by its own weight. In view of this, there has been provided an exposure apparatus provided with a bending suppression means for suppressing the bending of the photomask substrate mounted on the exposure apparatus.

  For example, in the apparatus of Patent Document 1 shown in FIG. 1, the photomask 1 is held on the lower surface, where the mask holder 2 that holds two sides of the photomask and the edges on both sides of the photomask 1 are positioned upward. The deflection correction is performed based on the principle of scissors by the two deflection correction bars 3 pressed from above.

  Further, in the apparatus of Patent Document 2 shown in FIG. 2, when holding the photomask M by holding (sucking) the upper surface, an airtight chamber SA is formed above the photomask M, and the airtight chamber SA is suctioned with air. A method is adopted in which the photomask M is levitated through the path 1b and the photomask M is levitated in the direction opposite to the direction of gravity by using the negative pressure of the hermetic chamber SA to correct the deflection of the photomask M.

  Therefore, the inventors performed a simulation on the correlation between the bending suppression means and the bending of the photomask substrate. FIG. 3 shows a simulation in which the holding member for holding the two sides and the bending suppression means for suppressing the bending by the principle of scissors are applied. FIG. 3A shows a state in which the photomask substrate is mounted on the proximity exposure apparatus. The photomask substrate is supported from below by holding members that support it from below in the vicinity of the two opposite sides (two sides spaced apart by 800 mm). Then, the bending behavior of the photomask substrate when the force pressed from above was gradually changed outside the holding member was calculated. In FIG. 3B, the horizontal axis indicates the position (mm) on the photomask substrate, and the vertical axis indicates the amount of deflection (μm). Moreover, each line segment in the figure shows the bending behavior when the pressure is changed, and the pressing is based on the pressure (1) when the bending becomes zero.

  As shown in FIG. 3B, as the pressure applied from above is gradually increased, the amount of deflection at the center of the photomask substrate gradually decreases, and at some point, the deflection is substantially reduced. Eliminate. When the pressure is further increased, the photomask substrate is warped upward.

  Thus, it can be seen that the in-plane non-uniformity of the proximity gap due to the deflection of the photomask substrate is reduced if the deflection suppressing means provided in the exposure apparatus is appropriately used. In other words, if the main cause of the variation due to the proximity gap position is a deflection due to the weight of the photomask substrate, it is considered that this variation can be suppressed to some extent by the deflection suppressing means of the exposure apparatus.

  The present inventors have further developed this knowledge, and studied a photomask substrate capable of managing fluctuations due to the proximity gap position with higher accuracy and enabling high-definition pattern transfer which becomes increasingly difficult. That is, in order to improve the transfer accuracy, the inventors have earnestly studied that they have obtained the knowledge that it is not sufficient to simply take the above-described means for suppressing the bending due to the weight of the photomask substrate.

(Evidence that bending suppression means alone is considered insufficient)
Since there are a plurality of methods and shapes of the photomask holding method and the deflection suppressing means of such an exposure apparatus, the direction and magnitude of the force received by the photomask substrate and the pressure per area are not the same due to these differences. Accordingly, even if the self-weight deflection is completely eliminated by the deflection suppressing means, the photomask substrate differs depending on the contact (or contact surface, tangent) with the holding member of the exposure apparatus and the contact with the deflection suppression means (same). , Is considered to have received various kinds of power. The direction and magnitude of the force received by the photomask substrate and the pressure per area are presumed to be different depending on the photomask holding method and the deflection suppressing means of the exposure apparatus. Furthermore, even if the same holding method or the like is adopted, it is presumed that it varies depending on the size of the photomask substrate, the maintenance method of each exposure apparatus, and the like. Further, the stage of the exposure apparatus on which the glass substrate constituting the transfer target is placed is not a completely flat surface, and thus has a factor that affects the proximity gap. These factors are thought to cause fluctuations due to the proximity gap position and to affect the transfer accuracy. In particular, along with the miniaturization of transfer patterns, proximity gap fluctuations due to various factors of the exposure apparatus cannot be ignored in precise transfer of patterns with a line width of 2 to 15 μm, and further about 3 to 10 μm. Yes.

  In view of the above, the bending suppression means described in Patent Document 1 and Patent Document 2 alone is insufficient for controlling the proximity gap. Furthermore, even with a substrate having a “cross-sectional arc shape with a concave surface on the side facing the mother glass” described in Patent Document 3, fluctuations in the proximity gap due to factors other than self-weight deflection cannot be reliably suppressed.

  Therefore, the present inventor has intensively studied to suppress the in-plane variation of the proximity gap, and has obtained the following solution. Hereinafter, an embodiment of the present invention will be described.

(Process for obtaining a photomask substrate according to this embodiment)
As a material for the photomask substrate applied to this embodiment, a glass material can be used. For example, quartz glass, alkali-free glass, borosilicate glass, aluminosilicate glass, and soda lime glass can be used.

  In the present application, the “photomask substrate” is a material for a photomask blank, and refers to a state of a transparent substrate obtained by processing the front and back of a flat plate such as glass into a predetermined shape and flatness. However, the photomask substrate portion is substantially the same even when a thin film is formed on the photomask substrate in this state or a resist is further applied (photomask blank) and the thin film is patterned (photomask). The photomask substrate is sometimes referred to as appropriate.

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

1. Gap Data and Unique Gap Data Acquisition Step First, the amount of variation due to the proximity gap position of a predetermined exposure apparatus is grasped. The proximity gap is measured by mounting the sample mask substrate on the photomask holder of the exposure apparatus, placing the sample glass substrate on the stage on which the transfer object of the exposure apparatus is placed, and measuring the distance between them. Can be implemented. That is, the proximity gap which is the distance between the sample mask substrate and the sample glass substrate is grasped at a plurality of positions on the main surface of the sample mask substrate. Specifically, each of the proximity gaps at a plurality of measurement points on the main surface of the sample mask substrate is measured. For example, in the region corresponding to the pattern region on the main surface of the sample mask substrate, lattice points with a predetermined constant interval (for example, a predetermined value within a range of 10 mm to 300 mm) are set, and each lattice point is used as a measurement point. be able to. The distance between the lattice points is more preferably selected within a range of 50 mm to 250 mm, for example.

  The pattern region can be a region excluding a region within 50 mm from the four sides forming the outer edge of the main surface of the sample mask substrate.

  The proximity gap is measured by, for example, irradiating light from 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. Can be done. Or you may apply the method of measuring using reflection of the glass plate which comprises an airtight chamber, as described in patent 3953841.

  Here, a case will be described as an example in which an exposure apparatus that holds two sides and is held on the lower surface and includes an apparatus that is provided with a bending suppression means that presses the outside of the holding member from above.

  When measuring the proximity gap, it is preferable to use a deflection suppressing means of the exposure apparatus. For example, it is preferable to measure the proximity gap while applying the optimum conditions (conditions in which the deflection is substantially zero) obtained by the simulation shown in FIG.

  Since the proximity gap at each measurement point obtained in this manner varies (varies) depending on the position, the variation due to the position of the proximity gap is shown. Proximity gap data having such variations is referred to as gap data A.

  The gap data A obtained above is actually the flatness of the sample mask substrate (pattern surface, pattern surface and back surface in the case of holding the upper surface) and the flatness of the sample glass substrate (transfer surface and its surface). This means a proximity gap that is influenced by the backside. However, for the purpose of this embodiment, it is preferable to obtain gap data that does not include fluctuations other than the proximity gap fluctuation inherent in the exposure apparatus.

Among variations due to the proximity gap position, variations inherent in the exposure apparatus are reproducible variations in a predetermined exposure apparatus, and include the following (1) to (3).
(1) Gap fluctuation due to photomask weight deflection when a photomask substrate is mounted on the exposure apparatus (2) Mechanism (holding portion shape, contact area, etc.) that holds the photomask by the exposure apparatus, and deflection suppression Gap fluctuation due to means (pressing position, pressure) (3) Gap fluctuation due to unevenness of flatness of the stage on which the transfer target (glass substrate) of the exposure apparatus is placed

On the other hand, fluctuations other than those inherent to the exposure apparatus include the following (4) and (5).
(4) Gap variation due to non-uniformity of flatness of pattern surface of photomask substrate (in the case of holding the top surface, gap variation due to non-uniformity of flatness of the back surface is also included)
(5) Gap fluctuation due to unevenness of the flatness of the transfer surface and back surface of the transfer object (glass substrate) placed on the stage of the exposure apparatus.

  An object of the present embodiment is to obtain means for taking effective measures against gap fluctuations that are reproducible and that can calculate a quantitative correction amount as long as a predetermined exposure apparatus is used. Therefore, the proximity gap measurement, which is the basis for calculating the correction amount, should be performed using an ideal sample mask substrate with non-uniformity in flatness and an ideal sample glass substrate configured similarly. . However, in practice, it is difficult to obtain such an ideal substrate. Therefore, it is preferable to obtain data from which fluctuations specific to the exposure apparatus are extracted based on the gap data A. That is, it is preferable to remove components due to variations other than variations inherent in the exposure apparatus. Therefore, in the following, first, the gap fluctuation component due to the flatness of the used sample glass substrate is removed from the gap data A.

  Specifically, by preparing a plurality of sample glass substrates and measuring the proximity gap sequentially, and averaging the values for each measurement point of the gap data A obtained using each sample glass substrate, Eliminate individual differences. Thereby, the proximity gap fluctuation (above (5)) due to the sample glass substrate can be removed. This is the gap data shown in FIG. 4A (this is the gap data B).

  Next, a gap variation component due to the pattern surface flatness of the sample mask substrate is removed. Here, the flatness measurement is separately performed on the pattern surface of the sample mask substrate, and the obtained flatness data (shown in FIG. 4B) is shown in FIG. 4A for each corresponding measurement point. It can be subtracted from the gap data B shown.

As a measuring device used for the flatness measurement, for example, a flatness measuring machine manufactured by Kuroda Seiko Co., Ltd., or a device described in JP-A-2007-46946 can be applied. Specifically, a plurality of lattice points are provided at predetermined intervals on the pattern surface of the sample mask in the same manner as the above-described proximity gap measurement, and these lattice points are used as measurement points for flatness measurement. Then, when determining the substantially parallel reference plane to the main table surface of the sample mask substrate, with the height information of each measurement point with respect to the reference plane, which can be the flatness data. In measuring the flatness, it is preferable to measure by holding the substrate as the subject vertically so as not to be affected by gravity as much as possible.

  Therefore, the gap data C shown in FIG. 4C obtained by subtracting the flatness data shown in FIG. 4B from the gap data B shown in FIG. 4A is a variation in proximity gap unique to the exposure apparatus. (This is called inherent gap data).

  It should be noted that other methods may be used for removing the fluctuation components in the above (4) and (5). For example, with respect to (4), a plurality of sample mask substrates are prepared, and the values for each measurement point of the gap data A obtained by using each of them are averaged to obtain the above (4) for the used sample mask. ) Can be removed.

  For (5), flatness measurement is performed in advance for the two main surfaces of the sample glass substrate, and flatness data for each measurement point obtained (in fact, for each measurement point corresponding to both main surfaces) The difference in flatness data, that is, parallelism data) may be subtracted from the numerical value for each corresponding measurement point of the underlying gap data B.

  As described above, the obtained unique gap data indicates the gap variation depending on the position, which is unique to the exposure apparatus to be used. Based on this, the shape of the photomask substrate of this embodiment is determined.

2. Shape processing data acquisition process The inherent gap data obtained above is attributed to the exposure apparatus when an ideally flat photomask substrate and an ideally flat glass substrate are set in the exposure apparatus. This represents the gap variation that occurs. Therefore, in order to prevent the gap variation from occurring, the gap variation can be reduced to substantially zero by processing the pattern surface of the photomask substrate with a shape that reverses the variation in advance. it can. This state is shown in FIG. FIG. 4D shows shape processing data for forming a pattern surface having an inverted shape based on the gap fluctuation shown in FIG. Here, in FIG. 4D, the surface shape of the photomask substrate corrected to cancel the gap fluctuation shown in FIG. 4C is viewed from the pattern surface side with the photomask substrate turned over. Since it shows, the corresponding position has moved to the left-right symmetrical position.

  FIG. 4D shows shape processing data for forming a pattern surface having an inverted shape based on the gap fluctuation shown in FIG. That is, if a photomask substrate having the pattern surface shape shown in FIG. 4D is prepared and a photomask is manufactured based on the photomask substrate, residual gap fluctuations are substantially eliminated in an actual exposure apparatus. This is shown in FIG.

  The above will be described with reference to FIG.

  In FIG. 5A, even if a photomask substrate having an ideal flatness and a panel substrate having an ideal flatness are set in an actual exposure apparatus, the proxy is changed according to the position in the plane. This shows a state in which a variation in the Mitty gap occurs. That is, the gap value is maximized at the portion where the distance between the photomask substrate and the panel substrate is maximized (FIG. 5B). This corresponds to the above-described inherent gap data (gap data C).

  Although the gap fluctuation range (difference between the maximum and minimum gaps) varies depending on the actual exposure apparatus, it is generally a numerical value within the range of 20 to 70 μm. For example, for an exposure apparatus having a gap fluctuation width of 50 μm, in order to make this zero, the 50 μm portion can be offset by shape processing of the pattern surface of the photomask substrate. The surface shape of the photomask substrate at this time is shown in FIG. In FIG. 5C, when the curve is a pattern surface, the upper side is the space side and the lower side is the photomask substrate side.

  From the viewpoint of transfer accuracy, the gap variation is preferably as small as possible. However, in proximity exposure, how much gap fluctuation due to in-plane position is allowed depends on the application and specifications of the product to be obtained. Is more preferable. The reason for this is that the shape processing of the photomask substrate to eliminate the gap variation is the actual production such as the removal amount of removal processing (polishing etc.) increases or the shape that is difficult to process becomes necessary. It is mentioned that it is not necessarily advantageous in terms of efficiency and yield.

  Therefore, a case where the gap variation allowable value according to the application product and the specification is taken into consideration in achieving in-plane uniformity of the proximity gap will be described below. For example, in the product to be obtained, the maximum allowable gap fluctuation value (hereinafter referred to as fluctuation tolerance T (μm)) can be a predetermined numerical value between 40 and 10 (μm). That is, depending on the required accuracy of the liquid crystal display device to be obtained, the extremely high definition can be 10 μm, the slightly loose specification can be 40 μm, and the intermediate can be appropriately 20 μm or 30 μm.

  FIG. 6 shows a process of determining the correction shape of the photomask substrate by fitting the gap data C with the variation allowable value T.

  In FIG. 6A, the correction shape is determined with respect to the gap data C on the basis of the maximum value (where the gap is maximum). That is, when the position P that becomes the maximum gap is matched with the upper limit of the variation allowable value T on the pattern surface after shape processing, a portion where the variation allowable value T cannot be satisfied (a portion where the gap becomes smaller than the allowable range. FIG. The shaded portion in (a) is corrected by shape processing. In other words, when the height of the position P that is the maximum gap is Z1, a portion that is lower than (Z1-T) is specified, and shape processing is performed to remove at least this portion. This method is the maximum value reference method.

Here, a height of say, can be a distance in the vertical direction with respect to the photomask main table surface (when assuming an ideal primary table surface), considered as the height relative to the ideal main table surface.

  For example, when the maximum value reference method is employed, a concave shape indicated by a dotted line in FIG. 6B may be formed on the pattern surface of the photomask substrate. Further, since this concave portion is a correction of a portion where the gap becomes too small, removal processing is necessary until the shape of the dotted line is reached, but further removal processing may be continued beyond this, until the solid line is reached. The removal process is allowed. That is, it can be said that the margin between the dotted line and the solid line is a margin for removal processing. And the area | region used as the process target between both becomes a specific area said by this invention. According to the maximum value reference method, the shape processing on the photomask substrate material forms a concave shape.

In FIG. 6 (c), with respect to the gap data C, with reference to the center value between the maximum value and the minimum value, and determines the corrected shape. That is, for a gap center value, T / 2 the portion gap is larger than the portion of the gap beyond the T / 2 becomes smaller, be corrected by shaping. In other words, when the height of the position where the proximity gap shows the median value is Z2, a portion where the height on the main surface is higher than (Z2 + T / 2), and (Z2−T / 2) The lower part is specified, and this part is specified to perform shape processing. This method is the central reference method.

  If the center reference method is adopted, as shown in FIG. 6D, the removal process may be performed as a dotted line, and a gap between the dotted line and the solid line is allowed as a margin for the removal process.

Further, in FIG. 6 ( e ), the correction shape is determined with respect to the gap data C on the basis of the minimum value (where the gap is minimum). That is, when the position B that becomes the minimum gap is set to the lower limit of the variation allowable value T on the pattern surface after shape processing, the portion where the variation allowable value T cannot be satisfied (the portion where the gap becomes larger than the allowable range, FIG. The hatched portion in (e) is corrected by shape processing. That is, when the height of the position B that is the minimum gap is Z3, a portion that is higher than (Z3 + T) is specified, and shape processing is performed so as to remove at least this portion. This method is the minimum value reference method.

Taking the minimum reference method may be the corrected shape as shown in FIG. 6 (f). Specifically, a convex shape indicated by a dotted line may be formed on the pattern surface, and an area between the dotted line and the solid line is allowed as a margin.

  Also in the center value reference method or the minimum value reference method, a region to be processed between the dotted line and the solid line in FIGS. 6D and 6F is a specific region.

  The correction shape differs depending on which of the above three methods is adopted. Therefore, the most appropriate method can be selected according to the apparatus and process used for processing.

  For example, the maximum value reference method is preferable because the removal amount (work amount) from the substantially flat photomask substrate material can be reduced. Further, when the removal process is a polishing process and a concave shape is formed on the surface, the removal amount is locally increased by increasing the polishing load of the part. When using such a method, it is more efficient to form a concave portion locally than to form a convex portion locally (removing the periphery of the position to be a convex portion). Is advantageous.

  Considering the above, the correction shape when the variation allowable value T is applied is determined. 4 (f) to 4 (n) show this in plan view.

  4C to 4E show the determination of the corrected shape so that the gap variation is eliminated when the allowable variation value T is set to zero and the shape-processed photomask substrate is used. (F)-(h) shows the case where correction | amendment shape determination is performed by the maximum value reference | standard method. In this case, the gap data shown in FIG. 4C is used as it is, and a photomask substrate having a surface shape obtained by reversing the gap data is not formed, but the maximum value position in FIG. Only the portion where the allowable value (35 μm in this case) could not be satisfied was subjected to shape processing. As is apparent from FIG. 4G, it can be seen that the shape processing only needs to form the recesses. Further, according to FIG. 4H, it is understood that the gap fluctuation remains after the shape processing, but the fluctuation width is 35 μm or less of the fluctuation allowable value T.

  Similarly, FIGS. 4I to 4K show shape processing data and gap fluctuation remaining after shape processing when the central reference method is adopted. 4 (l) to 4 (n) show similar data when the minimum value reference method is adopted.

3. The process generally performing shape processing in the photomask substrate, a photomask substrate, providing a glass substrate material for a photomask, two main table surface can be planarized by polishing. For example, a glass substrate material having a flatness of 5 to 30 μm can be used on each of the pattern surface and the back surface of the pattern surface. The glass substrate material thus obtained can be used as a photomask substrate material and further processed to obtain the photomask substrate of this embodiment.

  The shape to be processed is determined by the method described above. For example, the shape processing data shown in FIG. 4G can be used for shape processing by a known processing apparatus.

  For example, shape processing is performed using a polishing apparatus that includes a rotatable polishing surface plate, a polishing pad provided on the polishing surface plate, and an abrasive supply unit that supplies an abrasive to the surface of the polishing pad. be able to. When holding the glass substrate material on the polishing pad and trying to form a recess by shape correction, press the polishing pad so that the pressure of the polishing pad against the substrate is larger than other areas, and polish the glass substrate material on one side Can do. When pressing, an apparatus having a plurality of pressurizing bodies and having a control means capable of independently controlling pressure and pressurization on each pressurizing body is preferable. In the case of forming the convex portion, it is possible to control the pressurization so as to obtain a larger removal amount with respect to the peripheral region of the convex portion.

  Alternatively, shape processing using a vertical milling machine may be performed. A polishing cup head with an abrasive cloth attached to the processing portion of the apparatus can be attached, an abrasive liquid can be supplied, and processing can be performed while controlling the height direction.

  In the polishing step, the glass substrate material subjected to rough polishing and precision polishing may be subjected to the above shape processing, or after rough processing, the shape processing data is reflected simultaneously with the precision processing. The processed shape may be performed.

  The type and particle size of the abrasive used can be appropriately selected according to the substrate material and the flatness to be obtained. Examples of the abrasive include cerium oxide, zirconium oxide, and colloidal silica. The particle size of the abrasive can be several tens of nm to several μm.

4). Configuration of Photomask Substrate The photomask substrate according to this embodiment is configured as follows.
That is, a transfer pattern is formed on the main surface, mounted on a proximity exposure apparatus, exposed with a proximity gap between a transfer object placed on the stage of the proximity exposure apparatus, and the transfer A photomask substrate for forming a photomask used for transferring a pattern for use,
The photomask is formed by forming a concave shape, a convex shape, or a concavo-convex shape in one or a plurality of specific regions on the main surface by performing shape processing with a different removal amount from the peripheral region outside the specific region. Variation due to the position of the proximity gap that occurs when the substrate is mounted on the proximity exposure apparatus is reduced; and
The shape processing is configured as a photomask substrate that reduces variations inherent in the exposure apparatus extracted from variations due to the position of the proximity gap.

The concave shape, convex shape, or concave / convex shape mentioned above means a shape obtained when the influence of gravity is eliminated from the photomask substrate. Also. The peripheral region refers to a peripheral region outside the specific region and adjacent to the specific region. And this particular area, be any area on the main table surface of the photomask substrate, a region to be shaping. It can be a shape processing region represented by a dotted line or a solid line in FIGS. 6B, 6D, and 6F. One or more specific regions are set on the main surface. In the case of setting a plurality, there are no restrictions on the types of convex shapes, concave shapes, and concave-convex shapes, and combinations thereof.

  As a processing method, for example, removal processing for removing the surface portion by polishing or the like can be applied. In addition to polishing, a method such as sandblasting can also be applied. The removal amount different from the peripheral region means shape processing as deeper removal or shallower removal than the periphery. By increasing or decreasing the removal amount (for example, the polishing amount), a portion having a relatively higher or lower height than other regions can be formed. Alternatively, by removing only a specific region, the height may be relatively lower than other regions.

  Note that the shape processing can be performed so that the gap fluctuation inherent in the exposure apparatus is within the allowable range of the product (which is equal to or less than the fluctuation allowable value T). This variation allowable value T is determined based on the application and specification of the device to be manufactured using the photomask of this embodiment. Therefore, the proximity gap variation formed when the photomask substrate of this embodiment is mounted on the exposure apparatus is less than the gap allowable value T with respect to an ideal glass substrate.

  In the present invention, when the region excluding the region within 50 mm from the four sides forming the outer edge of the main surface of the photomask substrate is used as the pattern region, the shape processing is applied to the pattern region. It is preferable. On the other hand, in the area within 50 mm from the four sides (outside the pattern area), the above-described shape processing can be omitted, and in this case, the following points are advantageous.

  When considering using the photomask substrate mounted on the above-described two-side holding and lower-side holding exposure apparatus, the photomask substrate has two opposite sides of the pattern surface (the pattern surface of the photomask substrate is In the case of a rectangle, the region within 50 mm from the opposing long side) is preferably a holding region in contact with the holding member of the exposure apparatus, and thus the photomask substrate surface preferably has high flatness.

  For example, when the difference in height between any two points separated by Pmm (5 ≦ P ≦ 15) in this region is Z μm, Z / P is preferably 0.08 or less.

  Further, considering that the photomask substrate of the present invention is mounted on an exposure apparatus that holds four sides and holds the lower surface, the holding member of the exposure apparatus is used for an area within 50 mm from the four sides of the pattern surface. In order to be in contact with the holding region, the photomask substrate surface preferably has high flatness, and the same Z / P as described above is preferably 0.08 or less.

  Further, when considering that the photomask substrate of the present invention is mounted on an exposure apparatus that holds four sides and holds the upper surface, the area within 50 mm from the four sides of the back surface of the pattern surface is held by the exposure apparatus. Since it becomes a holding region where the members come into contact, the surface of the photomask substrate is preferably highly flat, and in this region, Z / P is preferably 0.08 or less.

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

5. Step for Producing Photomask There are no particular restrictions on the use of the photomask substrate of this embodiment. For example, the present invention can be applied to the types of photomasks exemplified below. In particular, when the photomask is used for manufacturing a liquid crystal display device and used for manufacturing a CF (color filter) or a TFT (thin film transistor) substrate, the effect of the present invention is remarkably obtained.

  For example, a binary mask blank for manufacturing a photomask can be obtained by forming a light-shielding film as an optical thin film on the main surface of the photomask substrate obtained by the above process. As the light-shielding film, chromium, a film containing a chromium compound containing one or more selected from oxygen, nitrogen, and carbon in chromium, or a metal element selected from silicon, tantalum, molybdenum, tungsten, and the like Or the like, a film containing a metal containing a major component such as a metal, a metal oxide, a metal nitride, a metal oxynitride, a metal oxycarbide, a metal oxycarbide, or a metal oxynitride carbide can be used.

  Alternatively, as the optical thin film, a semi-transparent film that partially transmits exposure light during exposure can be used. A plurality of thin films may be stacked. The material of the semi-transparent film can also be selected from the same materials as the light shielding film, and the exposure light transmittance can be adjusted to 5 to 80% depending on the composition and film thickness.

  Furthermore, a multi-tone mask can be obtained by patterning using the light-shielding film or the semi-transparent film as appropriate. That is, a transfer pattern including a light-shielding part that shields exposure light, a semi-transparent part that partially transmits exposure light, and a light-transmitting part that substantially transmits exposure light when the transparent substrate is exposed. A multi-tone photomask having the above can be obtained. This is a mask for processing a resist pattern formed on a transfer object into a three-dimensional shape with different remaining film amounts (heights) depending on the position. This is performed twice on the transfer object using a single photomask. This is a mask capable of obtaining the above patterning effect. For example, it can be advantageously used for manufacturing a color filter having a plurality of photo spacers having different heights.

  As a method for forming the optical thin film, a known method such as a sputtering method or a vacuum deposition method can be applied.

In the photomask manufacturing process, a known photolithography method can be applied. Primary table surface of the photomask substrate obtained by the above process (pattern surface), the optical thin film and the required number deposition, to produce a photomask blank further coated with a photoresist. Then, a pattern is drawn on the resist film using a drawing apparatus using a laser or an electron beam. Then, the drawn resist film is developed, and the optical thin film is wet-etched or dry-etched using the formed resist pattern as a mask to form a thin-film pattern. By repeating the photolithography process as many times as necessary, a photomask having a desired transfer pattern can be manufactured.

6). Process for performing pattern transfer As the exposure apparatus, a known proximity exposure apparatus can be used. As the exposure light source, a light source in a wavelength region including i-line, h-line, and g-line can be used.

  The photomask obtained by the photomask substrate of this embodiment is a photomask for use by being mounted on the exposure apparatus used for the above-described proximity gap measurement. As long as it is the same as the exposure apparatus used for measuring the proximity gap, the substrate holding mechanism of the exposure apparatus for holding the photomask substrate is not particularly limited. The above-described two-side holding, four-side holding, bottom surface holding, and top surface holding can be applied. When the deflection gap is measured at the time of measuring the proximity gap, the exposure is performed in the same manner at the time of pattern transfer.

  When the photomask substrate of this embodiment is mounted on the exposure apparatus, the photomask substrate is mounted with reference to the orientation of the photomask substrate determined when performing the shape processing. That is, the photomask substrate is mounted so that the orientation of the proximity gap coincides between the measurement of the proximity gap and the pattern transfer.

  As described above, the correction shape of the photomask substrate differs depending on how the gap variation allowable range (variable allowable value T) is applied. That is, the proximity gap setting value set in the exposure apparatus at the time of pattern transfer differs depending on whether the photomask substrate is processed into a concave shape or a convex shape.

  According to this embodiment, since the variation of the proximity gap can be controlled within a predetermined range, the setting value of the proximity gap itself can be made smaller than before. That is, 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 increased. For example, the set value of the proximity gap set in the exposure apparatus during pattern transfer can be set to 30 to 180 μm.

  As described above, according to the present embodiment, it is possible to largely eliminate the variation factor of the proximity gap caused by the exposure apparatus to be used. Note that the deflection of the photomask itself due to its own weight is one of the fluctuation factors of the proximity gap that occurs depending on the structure of the exposure apparatus to be used. However, according to the examination by the inventors, the exposure apparatus causes it. When there are fluctuation factors that cannot be ignored, according to the present embodiment, it is possible to effectively suppress such a variation in proximity gap.

  There is no particular limitation on the application of the photomask according to the present embodiment. As described above, when used as a photomask for manufacturing a liquid crystal display device, a remarkable effect can be obtained. For example, if the photomask according to this embodiment is used as a photomask for manufacturing a TFT substrate, the proximity gap can be controlled within a predetermined allowable range, so that the accuracy of the pattern line width and coordinates can be greatly improved. it can. Further, when used as a photomask for CF production, for example, when producing a black matrix or color plate, line width accuracy and coordinate accuracy can be greatly improved. In addition, when manufacturing photo spacers that control the accuracy of the gap between TFT and CF, the spacer shape (X direction, Y direction shape, height and slope shape in the Z direction in plan view) is improved. Effect is obtained.

7). Proximity Gap Evaluation Method As described above, according to the present embodiment, it is possible to accurately and efficiently evaluate the proximity gap when the photomask is set in the exposure apparatus.

Specifically, the sample mask substrate is mounted on the proximity exposure apparatus, the sample glass substrate is placed on the stage of the proximity exposure apparatus, and the proximity gap at a plurality of positions on the main surface of the sample mask substrate is measured. To obtain gap data indicating a change in proximity gap depending on the position;
Extracting a fluctuation component unique to the proximity exposure apparatus from the gap data to obtain the unique gap data;
By using the inherent gap data and a predetermined gap fluctuation allowable value, a position where a proximity gap exceeding the fluctuation allowable value is generated and an excess amount thereof are obtained, and when the photomask is set in the exposure apparatus. Proximity gaps can be evaluated accurately and efficiently.

<Other embodiments of the present invention>
As mentioned above, although embodiment of this invention was described concretely, this invention is not limited to the above-mentioned embodiment, It can change variously in the range which does not deviate from the summary.

Claims (22)

A transfer pattern is formed on the main surface, mounted on a proximity exposure apparatus, exposed with a proximity gap between the transfer object placed on the stage of the proximity exposure apparatus, and the transfer pattern A photomask substrate for forming a photomask used to transfer
The photomask is formed by forming a concave shape, a convex shape, or a concavo-convex shape in one or a plurality of specific regions on the main surface by performing shape processing with a different removal amount from the peripheral region outside the specific region. Variation of the proximity gap caused by mounting the substrate on the proximity exposure apparatus due to the position is reduced; and
The shape processing, the proximity gap was extracted from variation due to position state, and are not to reduce the inherent variation in the proximity exposure device,
The variation inherent in the proximity exposure apparatus is a variation in the proximity gap caused by the sample mask substrate or the sample glass substrate used for the measurement from the variation of the gap data obtained by the measurement of the proximity gap. photomask substrate, characterized in der Rukoto obtained by removing the component. The variation inherent in the proximity exposure apparatus is a variation in the proximity gap caused by the sample mask substrate and the sample glass substrate used for the measurement from the variation of the gap data obtained by the measurement of the proximity gap. 2. The photomask substrate according to claim 1, wherein components are removed. 3. The photomask substrate according to claim 1, wherein a component of the proximity gap variation caused by the sample mask substrate used for the measurement is flatness data of the photomask substrate. 4. The removal of the proximity gap fluctuation component due to the sample glass substrate used for the measurement is performed by obtaining an average of the gap data values obtained using a plurality of sample glasses. Item 4. The photomask substrate according to any one of Items 1 to 3. Major surface wherein the shaping is performed, according to any of claims 1-4, which is characterized by having a corrected shape determined based on the inherent variation in the extracted the proximity exposure device Photomask substrate. The shape processing is performed only on a specific region on the main surface including a region where the inherent variation of the extracted proximity exposure apparatus exceeds a predetermined gap variation allowable value. The photomask substrate according to any one of claims 1 to 5, wherein: It said shape processing, on said main surface, a photomask substrate according to any one of claims 1 to 6, characterized in that for forming one or more recesses. A photomask having a transfer pattern formed on the main surface, mounted on a proximity exposure apparatus, and exposed by providing a proximity gap between the transfer object placed on the stage of the proximity exposure apparatus And a photomask substrate manufacturing method for forming a photomask used for transferring the transfer pattern,
By mounting the sample mask substrate on the proximity exposure apparatus, placing the sample glass substrate on the stage of the proximity exposure apparatus, and measuring the proximity gap at a plurality of positions on the main surface of the sample mask substrate, Obtaining gap data indicating a change in proximity gap due to
By removing a component of the proximity gap variation caused by the sample mask substrate or the sample glass substrate from the gap data, a variation component unique to the proximity exposure apparatus is extracted, and the unique gap data is extracted. Obtaining
Obtaining shape processing data to be applied to the photomask substrate using the inherent gap data and a predetermined gap variation allowable value;
And a step of performing shape processing on the main surface of the photomask substrate using the shape processing data. 9. The photomask according to claim 8 , wherein, in the step of obtaining the inherent gap data, a component of the proximity gap variation caused by the sample mask substrate is removed from the variation of the proximity gap at the plurality of positions. A method for manufacturing a substrate. The photomask substrate manufacturing method according to claim 9, wherein flatness data of the photomask substrate is used as a component of a proximity gap variation caused by the sample mask substrate. The component of the proximity gap fluctuation resulting from the sample glass substrate is removed from the fluctuation of the proximity gap at the plurality of positions in the step of obtaining the inherent gap data . A method for producing a photomask substrate as described in 1. The removal of the component of the proximity gap fluctuation caused by the sample glass substrate is performed by obtaining an average of the values of the gap data obtained using a plurality of sample glasses. Photomask substrate manufacturing method. 13. The photo according to claim 8 , wherein a deflection suppressing unit included in the proximity exposure apparatus is used in order to suppress the deflection due to the weight of the sample mask substrate when measuring the proximity gap. Manufacturing method of mask substrate. In the step of obtaining the shape processing data, a portion of the proximity gap fluctuation indicated by the unique gap data and having a position unique to the proximity exposure apparatus that exceeds the gap fluctuation tolerance is specified, and the specified part is specified. The method for manufacturing a photomask substrate according to claim 8 , wherein shape processing is performed on a specific region including Of the inherent gap data, when the height of the main surface at the position where the proximity gap is the maximum value is Z1, and the gap variation allowable value is T, the height on the main surface is (Z1-T The method for manufacturing a photomask substrate according to claim 8 , wherein a lower part is specified, and shape processing is performed on a specific region including the specified part. The method for manufacturing a photomask substrate according to any one of claims 8 to 15 , wherein the shape processing is to form one or a plurality of concave portions on a main surface of the photomask substrate. An optical thin film for forming the transfer pattern is formed on the main surface of the photomask substrate according to any one of claims 1 to 7 or the photomask substrate according to the production method according to any one of claims 8 to 16. A photomask blank characterized by the above. A photomask, wherein the transfer pattern is formed by patterning an optical thin film formed on a main surface of the photomask blank according to claim 17 by a photolithography method. The photomask according to claim 18 , wherein the photomask is used for manufacturing a liquid crystal display device. The photomask according to claim 19 is mounted on the proximity exposure apparatus used for the measurement of the proximity gap and exposed to transfer a transfer pattern formed on the photomask onto a transfer target. And a pattern transfer method. A method for manufacturing a liquid crystal display device, wherein the pattern transfer method according to claim 20 is used. In the proximity gap evaluation method of the proximity exposure apparatus,
By mounting the sample mask substrate on the proximity exposure apparatus, placing the sample glass substrate on the stage of the proximity exposure apparatus, and measuring the proximity gap at a plurality of positions on the main surface of the sample mask substrate, Obtaining gap data indicating a change in proximity gap due to
From the gap data, the component of the proximity gap variation caused by the sample mask substrate and the sample glass substrate is removed, and the variation component specific to the proximity exposure apparatus is extracted,
Obtaining inherent gap data;
Using the specific gap data and a predetermined gap fluctuation tolerance, determining a position where a proximity gap exceeding the fluctuation tolerance is generated, and an excess amount thereof ;
A proximity gap evaluation method characterized by comprising: