KR100617271B1 - Method for coating resist on blank mask - Google Patents

Abstract

A resist coating method of a blank mask is disclosed. The resist coating method of the blank mask according to the present invention comprises a spraying step of spraying a resist material on the mask substrate; A diffusion step of rotating the mask substrate at a predetermined first rotational speed at a predetermined first exhaust pressure or less to diffuse the resist material throughout the mask substrate; A first film forming step of forming a resist film having a predetermined thickness by rotating the mask substrate at a first rotational speed at a second exhaust pressure higher than the first exhaust pressure; A second film forming step of rotating the mask substrate at a second rotation speed lower than the first rotation speed to precisely adjust the uniformity of the thickness of the resist film; And a low speed drying step of drying the resist material by rotating the mask substrate at a third rotation speed lower than the second rotation speed. According to the present invention, it is possible to minimize the nonuniformity of the resist thickness of the four corners caused by coating the resist at a high rotational speed and the resulting fringe phenomenon by controlling the exhaust pressure together with the rotational speed during the resist coating.

Blank Mask, Shielding Plate, Spin Coating, Resist, Exhaust Pressure, Drying Speed

Description

Method for coating resist on blank mask

1 is a view showing a resist coating apparatus of a conventional blank mask,

2A is a view showing a process of performing a resist coating method of a conventional blank mask;

2B is a view showing a thickness distribution of a resist film of a blank mask manufactured by a resist coating method of a conventional blank mask;

3 is a view showing the configuration of a resist coating apparatus for performing a resist coating method of a blank mask according to the present invention;

4 is a view showing an example of a shield plate,

Figure 5 is a flow chart showing the implementation of a preferred embodiment for the resist coating method of the blank mask according to the present invention,

6 is a view showing the relationship between the rotational speed and the exhaust pressure over time in the resist coating method according to the present invention, and

7A and 7B show the thickness distribution of the resist film coated by the resist coating method according to the present invention with the process conditions shown in Table 1 and the resist coating method according to the present invention without performing the waiting step under the process conditions shown in Table 1, respectively. Is a diagram showing the thickness distribution of a resist film coated with a film.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resist coating method of a blank mask, and more particularly, to a method of coating a resist for applying photolithography technology to a blank mask on which a metal light shielding film and an antireflection film are deposited.

Photolithography technology using a photomask is essentially used for forming a semiconductor integrated circuit and a fine circuit for a TFT-LCD. The photomask is fabricated by forming a pattern on the blank mask using photolithography techniques. In this case, the blank mask is a product in which a photoresist called a resist is applied in order to apply photolithography technology after depositing a metal-based light shielding film and an antireflection film such as chromium by a reactive sputtering method on a transparent substrate. Recently, as the design rule according to the high integration of the semiconductor integrated circuit is refined, the pattern of the photomask used for the fine pattern is also required to be refined with high precision. And the uniformity of the resist coating film in the blank mask is a very important factor for the implementation of such a fine pattern.

1 is a view showing a resist coating apparatus of a blank mask used in the prior art.

Referring to FIG. 1, the resist coating apparatus 100 of a conventional blank mask includes an injection nozzle 110, a spin bowl 120, a rotary chuck 130, a motor 140, an exhaust line 150, and an exhaust damper. And a pressure gauge 170.

The injection nozzle 110 is positioned above the rotary chuck 130 to inject a resist material onto the mask substrate 190 mounted on the rotary chuck 130. The mask substrate 190 mounted on the rotary chuck 130 is a mask in which a chromium film is formed on the transparent substrate. When the resist film is formed on the chrome film of the mask substrate 190 by the resist coating apparatus 100 shown in FIG. 1, the mask becomes a blank mask. The spin bowl 120 accommodates the rotary chuck 130 and prevents the resist sprayed on the mask substrate 190 from being diffused to the outside during the rotation of the rotary chuck 130. The rotary chuck 130 receives the driving force from the motor 140 to rotate the mask substrate 190 mounted thereon. The motor 140 is set in the resist coating apparatus 100 so that the rotation time and the rotation speed are controlled by a control value. The exhaust line 150 communicates with the spin bowl 120 to form a movement path of the gas in the spin bowl 120. At this time, the air pressure in the spin bowl 120 may be represented by the exhaust pressure measured by the pressure gauge 170 installed in the exhaust line 150. The exhaust damper 160 controls the exhaust pressure in the exhaust line 150 by adjusting the exhaust velocity of the gas through the exhaust line 150. An exhaust fan (not shown) allows the exhaust pressure in the exhaust line 150 to be maintained at a constant level with the exhaust damper 160 open.

Figure 2a is a view showing the performance of the conventional resist coating method of the blank mask.

Referring to FIG. 2A, the resist coating method of the conventional blank mask includes a diffusion step and a drying step. The exhaust pressure is kept constant throughout the process, and in the diffusion step, the rotary chuck 130 rotates at a relatively high speed (for example, 1000 rpm or more) compared to the drying step. In this case, the resist thickness distribution of the blank mask is thin in the center and thick in the outer part, and the reflection of the light is not uniform at the corners of the blank mask, so that the fringes are diffused and reflected to the blank mask. There is a problem that occurs. The thickness distribution of the blank mask manufactured by the resist coating method of the conventional blank mask is shown in FIG. 2B.

As described above, when the photomask is manufactured by a blank mask manufactured by a conventional resist coating method, an uneven region is included in the region where the pattern of the photomask is formed, and thus the quality of the photomask pattern is measured. This will adversely affect the uniformity of the pattern size. This result is to reduce the yield in the semiconductor manufacturing process, as a result has a problem that causes a lot of burden in the manufacturing cost, production amount, time, etc. of the semiconductor manufacturing process.

SUMMARY OF THE INVENTION The present invention provides a resist coating method of a blank mask in which a resist film is uniformly coated on a mask substrate, so that thickness uniformity is excellent and fringes do not occur at edge portions of the blank mask caused by thickness variation. To provide.

In order to achieve the above technical problem, the resist coating method of the blank mask according to the present invention, the spraying step of spraying a resist material on the mask substrate; A diffusion step of rotating the mask substrate at a predetermined first rotational speed below a predetermined first exhaust pressure to diffuse the resist material over the entire mask substrate; A first film forming step of forming a resist film having a predetermined thickness by rotating the mask substrate at the first rotational speed at a second exhaust pressure higher than the first exhaust pressure; A second film forming step of rotating the mask substrate at a second rotation speed lower than the first rotation speed to precisely adjust the uniformity of the thickness of the resist film; And a low speed drying step of drying the resist material by rotating the mask substrate at a third rotation speed lower than the second rotation speed.

Accordingly, by controlling the exhaust pressure together with the rotational speed during the resist coating, the nonuniformity of the resist thickness of the four corner portions generated when the resist is coated at a high rotational speed and the resulting fringe phenomenon can be minimized.

Hereinafter, exemplary embodiments of a resist coating method of a blank mask according to the present invention will be described in detail with reference to the accompanying drawings.

3 is a diagram illustrating a configuration of a resist coating apparatus for performing a resist coating method of a blank mask according to the present invention.

 Referring to Figure 3, the resist coating apparatus 300 of the blank mask according to the present invention, the injection nozzle 310, spin bowl 320, rotary chuck 330, motor 340, exhaust line 350, The exhaust damper 360, the pressure gauge 370, the control means 380, and the shield plate 390.

The injection nozzle 310 is positioned above the rotary chuck 330 to inject a resist material onto the mask substrate 400 mounted on the rotary chuck 330. The injection nozzle 310 is rotated from an initial position at which the injection of the resist material is not performed to an injection position at which the injection of the resist material is performed. At this time, depending on the configuration of the device, it takes about three seconds for the injection nozzle 310 to move from the injection position to the initial position.

The mask substrate 400 placed on the rotary chuck 330 is a mask in which a chromium film is formed on a transparent substrate, and if the resist film is formed on the mask 400 by the resist coating apparatus 300 of the blank mask according to the present invention, the mask mask is formed. Becomes The rectangular blank mask is formed by forming a chromium film by reactive sputtering a metal material such as chromium on a transparent substrate such as synthetic quartz glass or soda lime glass, and coating a resist film on the chromium film. In addition, the resist means a resist such as a photoresist, an electron beam resist, and a chemically amplified resist used in the manufacturing process of the blank mask.

The spin bowl 320 accommodates the rotary chuck 330 and prevents the resist sprayed on the mask substrate 400 from being diffused to the outside during the rotation of the rotary chuck 330. The rotary chuck 330 receives the driving force from the motor 340 to rotate the mask substrate 400 mounted thereon. The motor 340 is set in the resist coating apparatus 300 so that the rotation time and the rotation speed are controlled by a control value. The exhaust line 350 communicates with the spin bowl 320 to form a movement path of the gas in the spin bowl 320. At this time, the air pressure in the spin bowl 320 may be represented by the exhaust pressure measured by the pressure gauge 370 installed in the exhaust line 350. The exhaust damper 360 adjusts the exhaust pressure of the exhaust line 350 by adjusting the exhaust velocity of the gas through the exhaust line 350. An exhaust fan (not shown) allows the exhaust pressure in the exhaust line 350 to be maintained at a constant level (for example, 100 to 1000 Pa) while the exhaust damper 360 is open.

The control means 380 controls the rotation time and rotation speed of the motor 340 by a control value set in advance, and opens and closes the exhaust damper 360 to adjust the exhaust pressure. At this time, unlike the conventional resist coating method of the blank mask to maintain a constant exhaust pressure during the entire process, the control means 380 of the resist coating apparatus of the blank mask according to the present invention rotates the rotary chuck 330 at a constant rotation speed In order to form a resist film having a predetermined thickness by opening the exhaust damper 360 to increase the exhaust pressure at a time after a predetermined time elapses from the start of diffusion of the resist material (that is, when the diffusion process is completed). A film forming process is performed.

In addition, the control means 380 maintains the exhaust pressure at the time of performing the drying process performed after the film forming process equal to the exhaust pressure at the film forming process. In addition, the control means 380 rotates the rotary chuck 330 at the rotational speed of two stages during the film forming process. At this time, when the rotary chuck 330 is maintained at the same speed as the diffusion process, a resist film having a predetermined thickness is formed, and the rotary chuck 330 is rotated at a speed lower than the rotation speed during the diffusion process. At the time point, the uniformity of the thickness of the resist film is precisely adjusted. In addition, the control means 380 diffuses the low speed drying process and the rotary chuck 330 by drying the resist material by rotating the rotary chuck 330 at a speed lower than the rotation speed in the film forming process after the film forming process is finished. It performs a high speed drying process to dry the resist material by rotating at a speed higher than the rotation speed in the process. In this case, in order to maintain the desired exhaust pressure at a desired time, the exhaust damper 360 is manufactured to be opened and closed at intervals of 0.1 degrees, and the control means 380 opens and closes the exhaust damper 360 according to a given process condition.

The shield plate 390 is positioned above the spin bowl 320, and shields at least a portion of the mask substrate 400 mounted on the rotary chuck 330 from the outside atmosphere to increase the air flow rate on the mask substrate 400. Change. The shielding plate 390 partially adjusts the volatilization rate of the solvent contained in the resist material applied to the mask substrate 400 according to the shape of the through hole formed therein.

4 illustrates an example of the shield plate 390. Referring to FIG. 4, the shielding plate 390 has a disc shape in which a through hole 392 is formed. In this case, the through holes 392 are disposed at regular angular intervals along the circumferential direction of the shielding plate 390, and each of the plurality of straight lines and each of both ends of the plurality of straight lines formed perpendicular to the radial direction of the shielding plate 390. And a shape formed by a plurality of connection arcs connecting the ends of straight lines adjacent to each other with a predetermined curvature. Regarding the shape of the penetrating portion 392 of the shielding plate 390, the value of the length W of the straight line, the radius of curvature R of the connecting arc, and the distance D from the center of the shielding plate 390 to the straight line Therefore, a difference in thickness distribution after resist coating occurs.

By using these characteristics, the resist film having excellent uniformity may be coated on the mask substrate 400 by changing the W, R, and D values of the portion where the thickness distribution needs to be partially adjusted. At this time, it is preferable that the length W of each straight line is set to be the same, and it is preferable to select within the range of 0-50 mm. However, if it is 0 mm, the exhaust pressure is rapidly increased in the corresponding portion, so that the vortex is likely to be formed, so the length W of the straight line is preferably designed to be at least 5 mm or more. On the other hand, it is preferable that the radius of curvature R of each connection arc is also set equally, and it is preferable that it is selected within the range of 0-100 mm-more preferably, the range of 5-50 mm. In addition, in designing the shielding plate 390, the value of D has a great relation with the thickness formation of the four corner portions of the mask substrate 400, and is preferably selected within the range of 70 to 140 mm.

Figure 5 is a flow chart showing the implementation of a preferred embodiment for the resist coating method of the blank mask according to the present invention.

Referring to FIG. 5, first, a resist material is sprayed onto the mask substrate 400 (S500). At this time, the injection of the resist material may be made in two steps. The first step is a static spraying step, in which the mask chuck 400 is rotated at a stop state or at a speed of 30 rpm or less in order to stably apply the resist to the mask substrate 400 during initial resist spraying. The resist is sprayed on at a flow rate of 1.0 ml / sec to 3.0 ml / sec. Since the resist must be prevented from splashing in the static spraying step, the spraying time is preferably set within 2 seconds. In addition, in order to minimize drying of the solvent, the lower exhaust damper 360 is closed to maintain the exhaust pressure in the range of 10 Pa to 30 Pa.

The second step is a dynamic spraying step. In the case of the rectangular blank mask, the spraying process is performed while rotating the mask substrate 400 at a relatively high rotational speed so that the resist can be applied to the four corner portions of the blank mask. This dynamic spraying step allows the resist to be applied to the mask substrate 400 in a flat and overall manner before the subsequent diffusion step is performed. At this time, the flow rate at which the resist is sprayed proceeds in the same manner as the static spraying step, and the spraying time is preferably within 4 seconds. In the dynamic spraying step, the rotational speed of the mask substrate 400 is preferably 200 rpm to 450 rpm. If the rotational speed of the mask substrate 400 is set to 200 rpm or less, it is difficult to achieve the purpose of dynamic spraying. If the rotational speed of the mask substrate 400 is set to 450 rpm or higher, the drying of the resist proceeds due to the high rotational speed, causing problems such as fringe phenomenon. Done. In addition, in the dynamic spraying step, it is preferable to close the exhaust damper 360 to minimize the drying of the resist and to spread the resist to the outside to maintain the exhaust pressure in the range of 10 Pa to 30 Pa.

Next, the rotation state of the mask substrate 400 is maintained at the same time as the end of the spraying step from the time when the spraying of the resist material is finished to the time when the subsequent diffusion step is started (S510). This waiting step is performed for the time required for the nozzle 310 to be ejected on the mask substrate 400, and when the nozzle 310 is on the mask substrate 400, the vortex is generated by the nozzle 310 and thus This is to prevent the thickness of the resist from being partially lowered. In the waiting step, the exhaust damper should be kept closed to prevent drying of the resist, and it is preferable to allow the damper to proceed within a range of not more than three seconds.

Next, the mask substrate 400 is rotated at a predetermined first rotational speed below a predetermined first exhaust pressure to spread the resist material over the entire mask substrate 400 (S520). This diffusion step is a step of adjusting the thickness using centrifugal force at a high rotational speed so that the thickness of the resist film maintains a thickness similar to the desired thickness. At this time, in order to quickly adjust to the desired thickness, it is preferable to close the exhaust damper 360 to maintain the exhaust pressure in the range of 10 Pa to 30 Pa to keep drying of the resist slow. In order to adjust the thickness of the resist to the desired thickness, the rotation speed and the rotation time of the rotation chuck 330 are adjusted in the diffusion step. The rotation speed is 1,000 rpm or less to suppress the fringe phenomenon caused by the centrifugal force during the high speed rotation. The rotation time can be added or subtracted according to the desired thickness. Rotational speed of the rotary chuck 330 of the diffusion step is different depending on the solvent contained in the resist, but is preferably set to 850rpm or less.

Next, a resist film having a predetermined thickness is formed by rotating the mask substrate 400 at a first rotational speed at a second exhaust pressure higher than the first exhaust pressure which is the exhaust pressure in the diffusion step (S530). The first film forming step is a step of controlling the shape of the resist thickness distribution while rapidly drying the resist spread on the mask substrate 400 after the diffusion step is performed. In the first film forming step, the rotational speed of the rotating chuck 330 is preferably maintained at the same speed as the diffusion step, and the shape is adjusted using the rotation time. Preferably, the rotation time of the mask substrate 400 in the first film forming step does not exceed 5 seconds. When the thickness distribution of the resist has a convex lens shape, the rotation time is increased, and the concave lens shape has a shape. It is desirable to reduce the rotation time. At this time, it is preferable to increase the drying speed of the solvent by opening the exhaust damper 360 to maintain the exhaust pressure in a high range of 200 to 800 Pa in order to form the resist quickly.

Next, the mask substrate 400 is rotated at a second rotation speed lower than the first rotation speed to precisely adjust the uniformity of the thickness of the resist film (S540). This second film forming step is performed to finely adjust the thickness distribution of the resist film of the mask substrate 400. For such fine adjustment, the rotational speed of the second film forming step is maintained at a level of 40 to 70% of the rotational speed of the first film forming step, and finely adjusted by adjusting the rotational speed and the rotation time within this range. In the second film forming step, it is preferable to increase the rotation time when the thickness distribution of the resist has the shape of the convex lens, and reduce the rotation time when the shape of the resist has the shape of the concave lens. In addition, when the rotation speed and the rotation time are increased, the center portion of the blank mask becomes flat, so that the thickness of the resist film is uniform by adjusting the rotation time and the rotation time of the first film forming step and the second film forming step. Can find a condition with

Next, the mask substrate 400 is rotated at a third rotational speed lower than the second rotational speed to dry the resist material (S550). In this case, the third rotational speed may be set equal to the first rotational speed, which is the rotational speed of the mask substrate 400 in the first film forming step. This low-speed drying step is to maintain the shape of the film by removing the solvent contained in the resist while maintaining the resist thickness distribution formed in the second film forming step, in order to prevent the thickness distribution tendency from rotating by 50 rpm or less Proceed with speed. Further, the exhaust pressure in the low speed drying step is kept the same as the exhaust pressure in the second film forming step.

Next, the mask substrate 400 is rotated at a fourth rotational speed higher than the first rotational speed to quickly dry the resist material (S560). This high speed drying step is a step for removing all the solvent that can be removed by the rotational force by proceeding by rotating the mask substrate 400 in the range of 1,000 rpm to 1,500 rpm. The rotation time of the mask substrate 400 in the high speed drying step may be set to rotate for a sufficient time to remove all the solvent, preferably not more than 100 seconds. In this low speed and high speed drying step, the solvent evaporation rate at a specific portion of the blank mask may be controlled by varying the flow rate of air in the center, side, and corners of the mask substrate 400 using the shield plate 390. By using such a shielding plate 390, it is possible to ensure uniformity with respect to the thickness of the resist film in the entire blank mask area.

6 is a view showing the relationship between the rotational speed and the exhaust pressure over time in the resist coating method according to the present invention. Referring to FIG. 6, in the resist coating method according to the present invention, the thickness distribution of the resist film may be more precisely adjusted by appropriately adjusting the rotation speed and the exhaust pressure of the mask substrate 400 during the process of the process.

The following table describes the process conditions for coating the resist substrate iP3500 (manufactured by Tokyo Ohka Kogyo) on the mask substrate 400 by the resist coating method according to the present invention.

division Rotation speed (rpm) Rotation time (seconds) Acceleration (rpm / sec) Exhaust Pressure (Pa) Static spraying step 5-30 0.5 ~ 2 0.5 or less 0 Dynamic injection stage 300-450 1 to 3 0.5 or less 0 Waiting 300-450 0.5 ~ 3 0.5 or less 0 Diffusion Stage 600-850 1-5 0.5 or less 0 First film formation step 600-850 1-5 0.5 or less 200-800 Second film formation step 200-500 1-10 0.5 or less 200-800 Low speed drying step 5-50 30-100 0.5 or less 200-800 High speed drying step 1000-1500 60-120 0.5 or less 200-800

At this time, the R, D, and W values of the penetrating portion formed in the shielding plate 360 are 210 mm, 90 mm, and 40 mm, respectively, and the injection flow rate of the resist material is 2.2 ml / sec.

According to the process conditions shown in Table 1, the average thickness of the resist film formed on the mask substrate 400 was 4,650 mm 3, and the thickness uniformity (that is, the maximum value-minimum value of the resist thickness) of the resist film was 25 mm 3. The thickness uniformity of the resist film was obtained by placing 11 × 11 gratings in the effective area of 132 × 132 mm in the mask substrate 400 having a width and length of 152 × 152 mm, and measuring them at 121 intersection points of the gratings. The result is.

7A and 7B respectively show the thickness distribution of the resist film coated by the resist coating method according to the present invention at the process conditions shown in Table 1 and the resist coating method according to the present invention without performing the waiting step at the process conditions shown in Table 1, respectively. Is a diagram showing the thickness distribution of a resist film coated by " 7A and 7B, since the four corner portions of the blank mask coated by the conventional resist coating method have a strong centrifugal force due to the high rotational speed, the drying of the resist proceeds quickly and shows a thickness distribution higher than the average. This causes a fringe phenomenon. On the contrary, it can be seen that the resist film coated by the resist coating method according to the present invention under the process conditions described in Table 1 is formed uniformly as a whole without a large difference in thickness between the four corner portions of the blank mask. On the other hand, the resist film coated by the resist coating method according to the present invention without performing the waiting step in the process conditions shown in Table 1 shows that the thickness of the center portion of the blank mask is about 30 mm 3, the overall uniformity is lowered have.

The following table describes the process conditions for coating the chemically amplified resist FEP171 (manufacturer: FUJIFILM) on the mask substrate 400 by the resist coating method according to the present invention.

division Rotation speed (rpm) Rotation time (seconds) Acceleration (rpm / sec) Exhaust Pressure (Pa) Static spraying step 0-30 0.5 ~ 2 1 or less 0 Dynamic injection stage 200-400 1 ~ 2.5 1 or less 0 Waiting 200-400 0.5 ~ 3 1 or less 0 Diffusion Stage 550-850 2 ~ 5 1 or less 0 First film formation step 550-850 1-5 1 or less 200-800 Second film formation step 300-450 1-10 1 or less 200-800 Low speed drying step 30-40 30-90 1 or less 200-800 High speed drying step 1000-1500 60-120 1 or less 200-800

At this time, the R, D and W values of the penetrating portion formed in the shielding plate 360 are 220 mm, 80 mm and 30 mm, respectively, and the injection flow rate of the resist material is 2.1 ml / sec.

According to the process conditions shown in Table 2, the average thickness of the resist film formed on the mask substrate 400 was 3,998 mm 3, and the thickness uniformity (that is, the maximum value-minimum value of the resist thickness) of the resist film was 30 mm 3. The thickness uniformity of the resist film was obtained by placing 11 × 11 gratings in the effective area of 132 × 132 mm in the mask substrate 400 having a width and length of 152 × 152 mm, and measuring them at 121 intersection points of the gratings. The result is. Considering that the uniformity specification typically required in the current blank mask is about 80 GPa and even about 50 GPa in special cases, the thickness uniformity of the resist film formed on the mask substrate 400 according to the process conditions shown in Table 2 is quite excellent. It can be seen that the result.

Since the resists used in the above-described embodiments include different solvents and all have different characteristics such as drying speed, the resists are excellent in terms of thickness uniformity. The present invention is not limited thereto and may be applied to all processes in which a liquid in a form in which a polymer is dissolved in a solvent is coated in the form of a polymer film using a spin coating apparatus. That is, the resist to which the present invention can be applied includes main chain cleavage type, dissolution inhibiting type and chemically amplified resist, and as a solvent, propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), 2-hep Tanone, methyl isoamyl ketone (MAK), ethyl lactate (EL), diethylene glycol ether (DYGLYME), anisole (ANISOLE), methyl cellosolve acetate (MCA) and the like can be used.

Although the preferred embodiments of the present invention have been shown and described above, the present invention is not limited to the specific preferred embodiments described above, and the present invention belongs to the present invention without departing from the gist of the present invention as claimed in the claims. Various modifications can be made by those skilled in the art, and such changes are within the scope of the claims.

According to the resist coating method of the blank mask according to the present invention, the non-uniformity of the resist thickness of the four corners caused by coating the resist at a high rotational speed by controlling the exhaust pressure with the rotational speed during the resist coating and the resulting fringes The phenomenon can be minimized, and a resist film having excellent uniformity over the entire effective area for uniformity-inhibiting conditions in several cases by using partial exhaust pressure control and multi-step coating process on the mask substrate using a shielding plate Can be formed.

Claims (16)

Spraying a resist material onto the mask substrate; A diffusion step of rotating the mask substrate at a predetermined first rotational speed below a predetermined first exhaust pressure to diffuse the resist material over the entire mask substrate; A first film forming step of forming a resist film having a predetermined thickness by rotating the mask substrate at the first rotational speed at a second exhaust pressure higher than the first exhaust pressure; A second film forming step of rotating the mask substrate at a second rotation speed lower than the first rotation speed to precisely adjust the uniformity of the thickness of the resist film; And And a low speed drying step of drying the resist material by rotating the mask substrate at a third rotational speed lower than the second rotational speed. The method of claim 1, The spraying step, A static spraying step of spraying a resist while the mask substrate is stopped; And And a dynamic spraying step of spraying a resist while the mask substrate is rotated. The method of claim 2, The resist coating method of the blank mask, characterized in that the mask substrate is rotated at 200 rpm to 450 rpm in the dynamic spraying step. The method of claim 1, The spraying step is performed at or below the first exhaust pressure, and the second film forming step is performed at or above the second exhaust pressure. The method of claim 4, wherein The low speed drying step is a resist coating method of a blank mask, characterized in that performed under the second exhaust pressure. The method according to any one of claims 1, 4 or 5, The first exhaust pressure is set in the range of 10 to 30 Pa, the second exhaust pressure is set in the range of 200 to 800 Pa resist coating method of the blank mask. The method according to any one of claims 1 to 5, In order to prevent the formation of the vortex by the spray nozzle for spraying the resist material onto the mask substrate, the predetermined atmosphere is terminated from the time when the spraying step is completed and the diffusion step is started. And a waiting step of maintaining the rotational state of the mask substrate at the same time as the end of the spraying step for a time period. The method of claim 7, wherein The waiting time is a resist coating method of a blank mask, characterized in that the spray nozzle is set to be greater than or equal to the time required to escape on the mask substrate. The method of claim 1, And drying the resist material by rotating the mask substrate at a fourth rotational speed higher than the first rotational speed. The method of claim 1, The first rotation speed is a resist coating method of the blank mask, characterized in that set to 850 rpm or less to improve the thickness uniformity of the resist material formed on the outer side of the mask substrate. The method according to claim 1 or 10, And the second rotational speed is set to 40% to 70% of the first rotational speed. The method according to claim 1 or 10, And the third rotational speed is set to 50 rpm or less so that the thickness distribution of the resist film formed on the mask substrate is maintained by performing the second film forming step. The method of claim 1, The spraying step to the low speed drying step is performed in a state where at least a part of the mask substrate is shielded by a disk-shaped shielding plate in which a through hole is formed, The through-holes are arranged at predetermined angular intervals along the circumferential direction of the shielding plate, and each of the plurality of straight lines formed at right angles to the radial direction of the shielding plate and end portions of the straight lines adjacent to both ends of the plurality of straight lines. A resist coating method of a blank mask, characterized in that formed in the shape of a figure formed by a plurality of connecting arcs connected at a predetermined curvature. The method of claim 13, The length of the straight line is determined in the range of 5 to 50 mm, and the distance from the center of the line connecting the ends of the adjacent straight lines to the connecting arc in the direction of the center of the shielding plate is determined in the range of 5 to 50 mm. Resist coating method of a blank mask, characterized in that. The method according to claim 13 or 14, The resist coating method of the blank mask, characterized in that the distance between the center line of the straight line facing each other of the plurality of straight lines and the remaining straight line is determined within the range of 70 to 140mm. The method according to any one of claims 1 to 5, The resist material is propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), 2-heptanone, methyl isoamyl ketone (MAK), ethyl ractate (EL), diethylene glycol ether (DYGLYME) Anisole (ANISOLE), methyl cellosolve acetate (MCA) A resist coating method of a blank mask, characterized in that it comprises a volatile solvent selected from the group consisting of.

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