JPH0580489A - Production of mask - Google Patents

Abstract

PURPOSE:To form phase shifter patterns by controlling the thickness of phase shifter films to an optimum value without fluctuating the thickness of the phase shifter films on a substrate by the ruggedness of the substrate. CONSTITUTION:This production process includes a stage 1 for forming a light shielding film having prescribed light shielding patterns on the substrate, a sage 2 for forming a film layer consisting of a radiation sensitive material on the substrate, a sage 3 for determining the irradiation quantity of active chemical rays in such a manner that the film thickness of the patterns is kept constant within transmission patterns regardless of the kinds of the transmission patterns in accordance with the information on the coating film thickness of the radiation sensitive material with respect to the kinds of the transmission patterns, a stage 4 for irradiating the surface of the film layer to the prescribed pattern shape by using inadiation quantity, and a stage 5 for forming the prescribed shifter patterns by developing the film layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection exposure mask used for forming fine patterns in various solid-state elements such as semiconductor elements, superconductor elements, magnetic elements and optical integrated circuit elements.

[0002]

2. Description of the Related Art Conventionally, formation of fine patterns in solid-state elements such as large-scale integrated circuits has been performed mainly by a reduction projection exposure method. Using this method, one of the methods that can dramatically improve the resolution is a method of introducing a phase difference between the light beams that have passed through the transmissive regions adjacent to each other on the mask (hereinafter referred to as the phase shift method and Call). In this method, for example, in the case of a repeating pattern of an elongated transmissive region and an opaque region, every other transmissive region is arranged so that the phase difference of light passing through the mutually transmissive regions on the mask becomes approximately 180 degrees. A transparent material (hereinafter referred to as a phase shifter) for introducing a phase difference is provided on the mask.

A mask used in the phase shift method can be manufactured by providing a phase shifter on a predetermined transmission region of a conventionally used chromium mask. Regarding this, for example, IEE, Transaction on Electron Devices, ED 29, No. 12 (1982), pages 1828 to 1836 (IEEE, Trans. Electron Devices, E
D29, No. 12 (1982) pp1828-183.
6).

[0004]

In the prior art, as a method of manufacturing a phase shift mask, a light-shielding film is processed to form a predetermined light-shielding pattern, and then a phase shifter material film is formed on the light-shielding film. There was a method of processing into the phase shifter pattern of. Here, since the light-shielding film has a certain predetermined thickness, irregularities corresponding to the light-shielding film thickness occur on the substrate surface after forming the predetermined light-shielding pattern. When a phase shifter film is formed on this substrate, the phase shifter film thickness varies on the substrate due to the unevenness of the substrate described above, and the pattern size and unevenness density.
There is a problem that the phase shifter film thickness deviates from the optimum value depending on (pattern density).

[0005]

The above problems have a predetermined light-shielding pattern used when projecting and exposing a mask pattern on a substrate using a projection optical system and a phase shifter pattern for imparting a phase difference to transmitted light. In the method for manufacturing a phase shift mask, a step of forming a light-shielding film having a predetermined light-shielding pattern on a substrate, a step of forming a film layer made of a radiation-sensitive material on the substrate, and the radiation for the type of the transmission pattern. Based on the information about the coating thickness of the sensitive material,
A step of determining the irradiation dose of the active actinic radiation so that the film thickness of the formed pattern is constant within the transmission pattern regardless of the type of the transmission pattern; and a predetermined amount on the film layer using the irradiation dose. Irradiating the active actinic radiation in a pattern of
By developing the film layer to form a predetermined phase shifter pattern, by further performing a heat treatment at a temperature equal to or higher than the glass transition temperature of the radiation sensitive material after the step of forming the predetermined phase shifter pattern. ,
Further, it is achieved by using a charged particle beam or a laser beam as the active actinic radiation, and further by using a material containing at least a coating type silicon compound or a coating type glass having residual silanol groups and an acid generator as the radiation sensitive material. It

[0006]

In the case of the mask (reticle) used in the projection exposure method, a chromium film or a three-layer chromium film (chromium oxide / chromium / chromium oxide laminated film) having a thickness of about 80 to 100 nm is often used as a light shielding film. There is.

On the other hand, the optimum value of the phase shifter film thickness for making the above-mentioned light phase difference 180 degrees is generally determined by the following equation.

[0008]

## EQU00001 ## d = .lambda. / 2 (n-1) (1) where d is the phase shifter film thickness, .lambda. Is the exposure wavelength, and n is the refractive index of the phase shifter film at the exposure wavelength .lambda .. i line (λ
= 365 nm), the refractive index is about 1.45 when a silicon oxide vapor-deposited film or a coatable silicon compound film is used as the phase shifter film.
It becomes about 0 nm. Also, a KrF excimer laser (λ = 2
48 nm), the refractive index is about 1.5 and the phase shifter film thickness is about 250 nm. As can be seen from the above, the thickness of the phase shifter is only about several times the thickness of the light shielding film.

By the way, generally, when a film layer is formed on a substrate having irregularities by a spin coating method, a vapor deposition method or the like, a variation in the film thickness occurs due to the irregularities of the substrate, and the film thickness varies in the plane of the substrate. On the other hand, in the phase shift method, in order to obtain the highest effect, it is necessary to accurately control the phase shifter condition so that the above-mentioned light phase difference becomes 180 degrees. For this purpose, the phase shifter film thickness must be controlled to an optimum value.

The structure of the phase shift mask is roughly classified into two types: a type in which a phase shifter film is provided between the light shielding film and the substrate, and a type in which a phase shifter is provided on the light shielding film. In the former type, after a phase shifter film is formed on a flat mask substrate surface, a predetermined light shielding pattern is formed on it.
Further, a predetermined region of the phase shifter film is etched to be manufactured. This type can reduce variations in film thickness of the phase shifter. However, because of the structure in which the phase shifter film is provided between the light-shielding film and the mask substrate, the phase shifter film must be processed by anisotropic dry etching so that the cross section becomes vertical, which makes the manufacturing process more difficult. It gets complicated. In addition, it is difficult to correct the defect of the phase shifter pattern as compared with the latter type.

On the other hand, the latter type is manufactured by etching a light-shielding film on a substrate to form a predetermined light-shielding pattern and then forming a predetermined phase shifter pattern thereon. In this case, it is possible to regenerate the phase shifter film after forming the light shielding pattern. For example, when a defect occurs in the phase shifter pattern once formed, it is possible to remove the defect, form the phase shifter film again, and process the phase shifter pattern. However, as described above, there is a drawback that the phase shifter film thickness is about several times the light-shielding film thickness, and the variation in the phase shifter film thickness is larger than the former type. Therefore, a technique is required to form the phase shifter pattern so that the film thickness of the phase shifter is constant regardless of the unevenness of the light shielding pattern.

Here, consider a case where a mask of the latter type is manufactured by directly forming a phase shifter pattern using a radiation sensitive material (for example, a resist material or a coating silicon compound) as the phase shifter material. in this case,
Although the phase shifter film is formed by the spin coating method, the coating film thickness varies due to the unevenness of the substrate. In general, FIG.
As shown in (3), the phase shifter film thickness tends to be smaller where the concavo-convex density is smaller and where the opening size of the light shielding pattern is larger. In addition, the film thickness of the phase shifter tends to be smaller near the center of the opening than near the end of the opening.

On the other hand, when the dose of active actinic radiation applied to the radiation-sensitive material is changed, the dissolution characteristics of the radiation-sensitive material in the developing solution are changed. Due to this property, the film thickness after development can be changed by appropriately selecting the irradiation amount of the active actinic radiation to be applied to the radiation sensitive material film as shown in FIG. Here, FIG. 3 shows an example of acting negatively on actinic radiation. The actinic radiation is
Although there are charged particle beams such as electron beams and ion beams, or far-ultraviolet light, electron beams and laser beams are generally used in the mask manufacturing process.

Using the characteristics of such a material, by selecting an appropriate actinic radiation dose and irradiating in a predetermined pattern, the film thickness of the radiation sensitive material film in a desired region on the mask, that is, It can be formed by controlling the film thickness of the phase shifter. For example, by setting the irradiation amount at a portion having a large uneven density to be smaller than that at a portion having a small uneven density, it is possible to reduce the variation in the phase shifter film thickness regardless of the unevenness of the substrate. Similarly, the same effect can be obtained by increasing the irradiation amount in the region where the opening size of the light shielding pattern is larger.
Further, if the irradiation amount in the vicinity of the end of the opening is smaller than that in the vicinity of the center of the opening, it is possible to reduce variations in film thickness within the opening. Note that the coating film thickness changes due to the combination of conditions such as the type of radiation-sensitive material, substrate uneven density, opening size, opening shape, coating method, etc. The film thickness can be controlled more accurately if it is determined.

The method described above can be realized, for example, by the steps shown in FIG. That is, based on the information about the coating thickness of the radiation-sensitive material for the type of the transmission pattern, the step of forming a light-shielding film having a predetermined transmission pattern, the step of forming a film layer made of the radiation-sensitive material on the substrate, Step 3 of determining the dose of active actinic radiation so that the film thickness of the formed pattern is constant within the transmissive pattern regardless of the type of the transmissive pattern. By performing step 4 of irradiating and step 5 of developing to form a phase shifter pattern, it is possible to suppress variation in film thickness and control the phase shifter film thickness to an optimum value. Here, when the negative type radiation sensitive material is used, the irradiation amount may be adjusted within a predetermined phase shifter pattern to be formed. On the other hand, in the case of the positive type, the portion other than the area irradiated with the active actinic radiation remains after the development. Therefore, in order to reduce the variation in the film thickness of the phase shifter, it is necessary to irradiate the area other than the phase shifter pattern with active actinic rays to adjust the film thickness, and the process is more complicated than the case of using the negative type. Become.

Next, the step of determining the dose of active actinic radiation will be described with a specific example. First, consider the case where the coating thickness of the negative radiation-sensitive material changes with respect to the linear isolated opening pattern dimension as shown by the solid line in FIG. 1 on the vertical axis
00% indicates the optimum value of the phase shifter film thickness. This value indicates the coating film thickness such that the phase shifter film thickness becomes the optimum value when the phase shift mask is completed. Here, in order to simplify the explanation, it is assumed that the coating film thickness in the opening pattern is constant. It should be noted that this solid line slightly changes in isolated opening patterns such as contact holes and periodic patterns.

In FIG. 4, the phase shifter film thickness has an optimum value (d '= 100%) for a pattern of dimension d or more. However, c '% for the dimension c, b'% for the dimension b,
It becomes a '% with respect to the dimension a, and the coating film thickness becomes thicker than the optimum film thickness.

On the other hand, consider the case where the film thickness of the negative type radiation sensitive material after development changes as shown in FIG. 3 with respect to the active actinic radiation dose. In order to control to the optimum film thickness value, the film thickness after development is 1 of the coating film thickness for each of the dimensions c, b, and a.
The irradiation amount may be set so as to be 00 / c ', 100 / b', 100 / a '.

From FIGS. 3 and 4, when the size of the isolated opening pattern is smaller than a, the dose of active actinic radiation is Ea, and when the size is larger than d, the dose is Ed. The doses Eb and Ec are used for the dimensions b and c. By irradiating and developing active actinic rays on a predetermined phase shifter pattern region by using the irradiation amount thus determined, FIG.
As shown in, the variation in the film thickness of the phase shifter can be reduced regardless of the pattern size. That is, the phase difference can be controlled to the optimum value.

Actually, as shown in FIG. 2, the film thickness varies within the opening pattern. However, by setting the active actinic radiation dose based on the principle described above, the inside of the opening pattern can be adjusted. It is possible to reduce the variation in the film thickness.

Depending on the type of radiation-sensitive material, a step of accelerating the pattern forming reaction, such as a heat treatment step, may be carried out after the irradiation with active actinic radiation for the purpose of increasing the sensitivity and before the development. For example, it is a chemical amplification material such as a material obtained by adding an acid generator to coated glass. By using such a material, the throughput of the mask manufacturing process can be improved.

By the way, since the mask is normally washed, the phase shifter pattern needs to have mechanical durability. When an organic polymer material such as a resist material is used as the radiation sensitive material, the mechanical durability is not so high and it is not optimal as a phase shifter material. However, when a coated silicon compound, for example, coated glass, or coated glass containing residual silanol groups and a material containing an acid generator is used as the phase shifter material, the temperature at which the material vitrifies after pattern formation, for example, 200 Sufficient mechanical strength can be obtained by heat treatment at a temperature of about ° C or higher. Therefore, these are suitable materials as phase shifter materials. It is preferable that the transmittance for the exposure light used is 90% or more in terms of pattern transfer characteristics, optical durability and the like.

When the heat treatment step is performed after the development, the film thickness of the formed pattern may be different from that before the heat treatment. In this case, it goes without saying that this amount of change must be taken into consideration in the step of setting the dose of active actinic radiation described above.

The case where the phase shifter film thickness is controlled to the optimum value without depending on the unevenness of the substrate has been described above. On the other hand, the phase shift method can obtain the highest resolution effect when the phase difference of light is 180 degrees, but depending on the shape and arrangement of the transmission pattern, the phase difference of light is a value other than 180 degrees, for example, The phase shifter film thickness may be set so as to be 60 degrees, 90 degrees, 120 degrees, or the like. This is the case, for example, as shown in FIG.

Even in such a case, by selecting the irradiation dose of the active actinic radiation as described above, the phase shifter film thickness,
That is, since the phase difference can be arbitrarily changed, it is possible to easily form a phase shifter pattern having a desired film thickness at a desired position on the mask. In this case as well, it goes without saying that the active actinic ray irradiation dose must be determined in consideration of the change of the coating film thickness depending on the pattern size and the like.

[0026]

【Example】

Example 1 An example of the present invention will be described below.

A 64 megabit DRAM (dynamic random access memory) wiring pattern manufacturing process phase shift mask having a minimum design dimension of 0.3 μm was manufactured. A manufacturing process of the phase shift mask for 10: 1 i-line (exposure wavelength 365 nm) reduction projection exposure having a numerical aperture NA = 0.42 according to this embodiment will be described with reference to FIGS.

First, a transparent conductive film 14 and a chromium film 13 were laminated in this order on a synthetic quartz substrate 11 (FIG. 7A). Here, the transparent conductive film 14 is provided to prevent charge-up during electron beam writing. The chromium film 13 is used as a light shielding film.

Although the chromium film is used as the light shielding film here, a film opaque to the exposure light, for example, a molybdenum silicide film or the like may be used. Note that a second phase shifter film may be provided between the transparent conductive film 12 and the chrome film 13 in order to facilitate the defect correction when a phase shifter defect occurs. The second phase shifter film may be provided on the chromium film.

Positive resist RE2000P on the substrate
(Hitachi Chemical Co., Ltd., product name) was applied to a film thickness of 0.5 μm.
After heat treatment at a temperature of 100 ° C for 30 minutes, accelerating voltage 30k
A predetermined transmission pattern was drawn with an electron beam using a V electron beam drawing apparatus. After that, predetermined development and heat treatment were performed to form a desired resist pattern.

Next, the chromium film was wet-etched using the resist pattern as a mask and using a predetermined etching solution and etching conditions. After that, the resist pattern was removed to form a desired transmission pattern (FIG. 7B).

Next, coating type glass OCD type 7 (Tokyo Ohka Co., Ltd., product name) was spin-coated on the substrate to form a coating type glass film 15 (FIG. 7 (c)). Here, the coating type glass film 15 is used as a phase shifter film. The material of the phase shifter film is not limited to this, and other coating type glass or organic polymer material may be used,
The transmittance for exposure light is preferably 90% or more.

Generally, the optimum value of the phase shifter film thickness is determined by the equation (1). Where d is the phase shifter film thickness, λ
Is the exposure wavelength, and n is the refractive index of the phase shifter film at the exposure wavelength λ. In this embodiment, λ = 365 nm and n = 1.
It was 45. According to the equation (1), the film thickness of the coating type glass film 15 is 406 nm. On the other hand, the coating type glass film 15 has a thickness of 90% of the coating thickness when the following steps are performed. Therefore, in the present embodiment, the coating film thickness of the coating type glass film 15 is set to 451 nm.

After that, the substrate was heat-treated at a temperature of 80 ° C. for 15 minutes using a hot air convection furnace. Here, the conditions of temperature and time of heat treatment are not limited to these values.

Next, a predetermined phase shifter pattern region was drawn by using an electron beam drawing device with an acceleration voltage of 30 kV. In the present embodiment, the dimensions of the transmission pattern in the light-shielding region where the phase shifter pattern is provided were 3 μm and 3.5 μm 2 on the mask. Further, a phase shifter pattern having a size of 6 μm was also arranged in the transmission region at the same time. On the other hand, in this example, the coating film thickness of the coating type glass film changed with respect to the size of the transmission pattern as shown in FIG. FIG. 8 shows the coating film thickness value at the center of the transmission pattern, and the film thickness value was about 20 nm at the end of the transmission pattern. Further, the coating type glass film thickness after development with respect to the electron beam irradiation amount changed as shown in FIG. In the present embodiment, the electron beam irradiation amount is set so that the central value of the transmission pattern is the same regardless of the pattern size.

From FIG. 8, the coating film thickness is 5 for a size of 3 μm.
The irradiation amount may be set so that the normalized film thickness after development is 85% in order to obtain 31 nm and 451 nm after development. Similarly, for a size of 3.5 μm, 5
Since it is 08 nm, the dimension is 6μ so that it is 89%.
Since it is 451 nm with respect to m, it may be 100%. 8 and 9, the electron beam irradiation amount when drawing a phase shifter pattern arranged on a transmission pattern of 3 μm is 245 μC / cm, 270 μC / cm for a transmission pattern of 3.5 μm, and 395 μC for a transmission pattern of 6 μm. /
I set it to cm. In the actual electron beam writing process, the phase shifter pattern and the transmission pattern provided with the phase shifter pattern may be misaligned. So 3μ
For the phase shifter patterns of m and 3.5 μm, patterns having dimensions of 5 μm and 5.5 μm were drawn around the transmission pattern.

In this embodiment, the electron beam irradiation amount is set in this way, but the drawing conditions change depending on the size and shape of the phase shifter pattern to be drawn, the material of the phase shifter film, the coating conditions of the phase shifter film, and the like.

After that, the substrate was developed with methanol for 30 seconds and dried, and then further heat-treated at a temperature of 200 ° C. for 30 minutes to form a phase shifter pattern. Here, the conditions of the heat treatment are not limited to the above, but in order to improve the mechanical durability, the heat treatment temperature is preferably the glass transition temperature of the material or higher, for example, 200 ° C. or higher.

Thus, a phase shift mask having a desired pattern was obtained (FIG. 7 (d)). Reduction ratio 10 of the manufactured phase shift mask and projection optical system with NA = 0.42:
When pattern transfer was performed using the i-line reduction projection exposure apparatus No. 1, the pattern could be transferred with good resolution.

<Embodiment 2> 6 having a minimum design dimension of 0.3 μm
A phase shift mask for a 4 megabit DRAM wiring pattern manufacturing process was manufactured. In this example, a predetermined transmission pattern was formed as described in Example 1, and coating glass was applied to a film thickness of 451 nm and heat-treated at a temperature of 80 ° C. for 15 minutes.

Next, a predetermined phase shifter pattern region was drawn by using an electron beam drawing device with an acceleration voltage of 30 kV. In this embodiment, the dimensions of the transmission pattern in the light-shielding area where the phase shifter pattern is provided are 3 μm and 3.5 on the mask.
was μm. Further, a phase shifter pattern having a size of 6 μm was also arranged in the transmission region at the same time. On the other hand, in the present example, the coating film thickness of the coating type glass film changed with respect to the size of the transmission pattern as shown in FIG. FIG. 8 shows the coating film thickness value at the center of the transmission pattern. For a pattern with a size of 3.5 μm, 1 μm from the end of the transmission pattern.
In the area of about m, the maximum coating film thickness is 20 from the value in FIG.
nm thickened. Further, the coating type glass film thickness after development with respect to the electron beam irradiation amount changed as shown in FIG.

FIG. 10 shows the method of setting the dose in this embodiment.
Will be explained. First, the width of the transparent pattern edge is 1.0μ.
It was divided into m 2 strips. As a result, one linear pattern was divided into a total of three areas including the pattern central area A and the two pattern end areas B. In the actual electron beam writing process, there is a possibility that the phase shifter pattern and the transmission pattern on which the phase shifter pattern is provided may be misaligned. So 3
Patterns with dimensions of 5 μm and 5.5 μm were drawn around the transmission pattern with respect to the phase shifter patterns of μm and 3.5 μm, respectively. Therefore, the region B also includes a region that does not overlap the transmission pattern. The coating film thickness in the region A was according to FIG. In addition, the film thickness at the edge of the pattern is 2 times larger than the film thickness at the center of the pattern for the size of 3.5 μm.
Since the thickness is about 0 nm, the coating film thickness in region B is (region A
Coating thickness of +10 nm).

From the above, when the phase shifter pattern arranged on the transmission pattern of 3 μm is drawn, the electron beam irradiation amount to the regions A and B is set to 245 μC / cm. Also, 3.5μ
For a transmission pattern of m 2, the area A is 270 μC / c
The area m and the area B were 260 μC / cm. Further, it was set to 395 μC / cm for a 6 μm phase shifter pattern.

In this embodiment, the electron beam irradiation amount was set in this way, but the pattern division method depending on the size, shape, density of the phase shifter pattern to be drawn, the material of the phase shifter film, the coating conditions of the phase shifter film, etc. Drawing conditions such as the number of divided areas and irradiation amount change.

After that, the substrate was developed with methanol for 30 seconds and dried, and then heat-treated at a temperature of 200 ° C. for 30 minutes to form a phase shifter pattern. Here, the conditions of the heat treatment are not limited to those described above, but the heat treatment temperature is preferably the glass transition temperature of the material or higher, for example, 200 ° C. or higher in order to improve the mechanical durability. As described above, a phase shift mask having a desired pattern was obtained.

A reduction ratio of 10 having the phase shift mask thus manufactured and a projection optical system with NA = 0.42:
1 i-line reduction projection exposure apparatus, coherency condition
When the pattern was transferred at 0.3, the pattern could be transferred with good resolution.

Example 3 A phase shift mask for a 256 megabit DRAM wiring pattern manufacturing process having a minimum design dimension of 0.25 μm was manufactured. The manufacturing process of the phase shift mask for 5: 1 KrF excimer laser (exposure wavelength 248 nm) reduction projection exposure according to this embodiment will be described.

First, the transparent conductive film 12 was laminated on the synthetic quartz substrate 11, and a silicon oxide film 25 was further deposited as a phase shifter film for defect correction. In formula (1), λ = 2
From 48nm, n = 1.5, the phase shifter film thickness is 248n
m. Therefore, the thickness of the silicon oxide film 25 is set to 248.
nm. Here, the material of the phase shifter film is not limited to these, and other materials may be used, but it is preferable that the transmittance for the exposure light is 90% or more.

After that, a chromium film having a thickness of 80 nm was vapor-deposited as a light-shielding film on the substrate. Next, a positive resist RE2000P (Hitachi Chemical Co., Ltd., product name) is formed on the substrate to a film thickness of 0.5.
It was applied to a thickness of μm. After heat treatment at a temperature of 100 ° C. for 30 minutes, a predetermined transmission pattern was drawn with an electron beam using an electron beam drawing device with an acceleration voltage of 30 kV. After that, predetermined development and heat treatment were performed to form a desired resist pattern. next,
The chromium film was wet-etched using the resist pattern as a mask and using a predetermined etching solution and etching conditions. Then, the resist pattern was removed to form a desired transmission pattern. Next, coating glass OCD type 7 (Tokyo Ohka Co., Ltd., product name) was spin-coated on the substrate to form coating glass film 21 as a phase shifter film. Formula (1)
At λ = 248 nm and n = 1.49, the phase shifter film thickness becomes 253 nm. On the other hand, the coating type glass film 20
Is 90% of the coating thickness when the following steps are performed.
Becomes thick. Therefore, in this embodiment, the coating film thickness of the coating type glass film 20 is set to 281 nm. Here, the material of the phase shifter film is not limited to the above, and other materials may be used, but it is preferable that the transmittance for the exposure light is 90% or more. Then, the substrate was heat-treated for 15 minutes at a temperature of 80 ° C. using a hot air convection furnace. Here, the conditions of temperature and time of heat treatment are not limited to the above values.

Next, a predetermined phase shifter pattern region was drawn by using an electron beam drawing device with an acceleration voltage of 30 kV. In the present example, the dimensions of the transmission pattern in the light-shielding region where the phase shifter pattern is provided were 1.25 μm and 1.5 μm on the mask. On the other hand, the coating film thickness of the coating type glass film in this example was 280 nm in the central part of the transmission pattern and about 295 nm in the region having a width of about 0.5 μm from the end of the transmission pattern. Further, the coating type glass film thickness after development with respect to the electron beam irradiation amount changed as shown in FIG.

In this embodiment, the pattern is divided into regions A and B as described in the second embodiment. However, although the width of the region B is set to 0.5 μm, this value changes depending on the coating conditions and the like. From FIG. 9, the electron beam irradiation amount when drawing the region A is 3
95 μC / cm. In region B, the normalized film thickness is 280
/ 295 = 0.95 so that the irradiation dose is 34 from Fig. 9.
It was set to 0 μC / cm.

Although the electron beam irradiation amount is set in this way in the present embodiment, the drawing conditions change depending on the size of the phase shifter pattern to be drawn, the material of the phase shifter film, the film thickness of the phase shifter, the coating conditions of the phase shifter film, and the like.

After that, the substrate was developed with methanol for 30 seconds and dried, and then heat-treated at a temperature of 200 ° C. for 30 minutes to form a phase shifter pattern. Here, the conditions of the heat treatment are not limited to those described above, but the heat treatment temperature is preferably 200 ° C. or higher in order to improve the mechanical durability. Thus, a phase shift mask having a desired pattern was obtained.

When the film thickness of the phase shifter pattern of the phase shift mask thus manufactured was measured by using a film thickness measuring device, a desired value of 250 ± 5 nm was obtained. Furthermore, the phase shift mask and N manufactured in this way
KrF with a projection optical system of A = 0.42 and a reduction ratio of 5: 1
When pattern transfer was performed using an excimer laser reduction projection exposure apparatus, the pattern could be transferred with good resolution.

[0055]

According to the present invention, the phase shifter pattern can be formed by controlling the phase shifter film thickness to an optimum value without causing the phase shifter film thickness to vary on the substrate due to the unevenness of the substrate surface.

[Brief description of drawings]

FIG. 1 is a flowchart of a mask manufacturing method according to an embodiment of the present invention.

FIG. 2 is an explanatory view showing a cross section of a phase shift mask.

FIG. 3 is a sensitivity characteristic diagram of a radiation-sensitive material with respect to actinic radiation.

FIG. 4 is a characteristic diagram showing a relationship between an opening pattern size and a radiation-sensitive material coating film thickness.

FIG. 5 is an explanatory view showing a cross section of a phase shift mask.

FIG. 6 is an explanatory view showing the arrangement of phase shifters.

FIG. 7 is an explanatory diagram of a mask manufacturing process according to the first embodiment.

FIG. 8 is a characteristic diagram showing the relationship between the pattern size and the coating type glass coating film thickness in Example 1.

9 is a sensitivity characteristic diagram of the coating type glass in Example 1 against an electron beam. FIG.

FIG. 10 is an explanatory diagram showing a method of setting an active actinic radiation dose in Example 2.

[Explanation of symbols]

1 step of forming a light-shielding film having a predetermined transmission pattern, 2
… Step of forming radiation sensitive material film, step of setting irradiation dose of active actinic radiation, step of irradiation of actinic actinic rays in a predetermined pattern with the above dose, step of developing and patterning Forming step.

Claims (6)

[Claims] 1. A method of manufacturing a phase shift mask having a predetermined transmission pattern used when projecting a mask pattern onto a substrate using a projection optical system and a phase shifter pattern for giving a phase difference to the transmitted light, Forming a light-shielding film having the predetermined transmission pattern on the substrate; forming a film layer made of a radiation-sensitive material on the substrate;
Based on the information about the coating film thickness of the radiation sensitive material for the type of the transmission pattern, the active actinic radiation is applied so that the film thickness of the formed pattern is constant in the transmission pattern regardless of the type of the transmission pattern. A step of determining an irradiation amount, a step of irradiating the active actinic radiation in a predetermined pattern on the film layer using the irradiation amount, and a step of developing the film layer to form a predetermined phase shifter pattern A method for manufacturing a mask, comprising: 2. The mask manufacturing method according to claim 1, wherein after the step of developing the film layer to form the predetermined phase shifter pattern, a step of heat-treating at a temperature equal to or higher than a glass transition temperature of the radiation sensitive material is performed. 3. The mask manufacturing method according to claim 1, wherein the active actinic radiation is a charged particle radiation. 4. The mask manufacturing method according to claim 1, wherein the active actinic radiation is laser light. 5. The mask manufacturing method according to claim 1, wherein the radiation-sensitive material is a coatable silicon compound. 6. The mask manufacturing method according to claim 1, wherein the radiation-sensitive material is a material containing coated glass containing residual silanol groups and an acid generator.