KR102685030B1 - Method for manufacturing photomask - Google Patents

Abstract

A method for manufacturing a photomask capable of forming patterns with different optical characteristics by suppressing the occurrence of overlap errors during exposure is provided.
A photomask blank having a semi-transmissive film, an intermediate film, and an upper layer film is prepared on a transparent substrate, and the photoresist film formed on the upper layer film is exposed to form a first region, a second region, and a third region with different exposure amounts. . Thereafter, the first region is selectively removed and the upper layer film is etched. Thereafter, the second region is selectively removed, the semi-transmissive film is etched, and the upper layer film and middle film are also etched. Afterwards, the third area is removed.

Description

Photomask manufacturing method {METHOD FOR MANUFACTURING PHOTOMASK}

The present invention relates to a method of manufacturing a photomask.

Photomasks are used in the process of manufacturing electronic devices such as flat panel displays. Conventionally, a binary mask having a transmitting portion and a light-shielding portion has been used as a photomask. However, in recent years, for example, a phase shift mask including a light shielding film and a phase shift film to form a fine pattern, or a multi-gradation photomask may be used to reduce the number of manufacturing processes for electronic devices. Such photomasks have multiple patterns with different optical properties on a transparent substrate, and multiple pattern drawing (exposure) processes are required to form these patterns.

Patent Document 1: Japanese Patent Application Publication No. 2017-76146 Patent Document 2: Japanese Patent Application Publication No. 2013-134435

When forming a semi-transmissive region and a light-shielding region having different optical characteristics, photoresist exposure (drawing) processing is required for each pattern formation, and the number of manufacturing processes increases. Additionally, since exposure processing is performed by setting the photomask substrate in an exposure (drawing) device each time each pattern is drawn, an overlap error (alignment misalignment) may occur. Therefore, it is necessary to arrange the pattern taking the overlap margin into consideration, making it impossible to obtain a detailed pattern.

A method for avoiding the occurrence of overlapping errors is disclosed in Patent Document 1. In Patent Document 1, a first etching is performed using the first resist pattern formed by preliminary development as a mask, and then additional development is performed to retract the edge portion of the first resist pattern, and then a second etching is performed, and a light-shielding portion is formed. A method of forming a phase shift film symmetrically on both sides is disclosed. However, although it is possible to prevent the occurrence of overlapping errors in the exposure device in the second etching, it is unstable and the pattern size is limited because unnecessary amount of light is used during exposure. Additionally, the patterns that can be formed are also limited.

Patent Document 2 discloses a method of forming a pattern made of another material. In Patent Document 2, a resist pattern is formed on a stack of a lower layer film and an upper layer film made of different materials, the upper layer film and the lower layer film are selectively wet etched using the resist pattern as a mask, and then the resist pattern is etched. A method of side etching the upper layer film using a mask is disclosed. Patent Document 2 uses a resist pattern formed in a single drawing process to prevent the occurrence of overlapping errors, but because it uses an unnecessary amount of light during exposure, it is unstable and the pattern size is limited.

In view of the above problems, the object of the present invention is to provide a method for manufacturing a photomask that can form patterns with different optical characteristics by suppressing the occurrence of overlap errors during exposure.

A. The first sun

The method for manufacturing a photomask according to the present invention is,

A process of preparing a photomask blank having a semi-transmissive film on a transparent substrate, a middle film on the semi-transmissive film, and an upper layer on the middle film;

A process of forming a photoresist film on the upper layer film;

an exposure process of exposing the photoresist film to form a first region, a second region, and a third region with different exposure amounts;

a first resist removal process for selectively removing the first region;

a first etching process of etching the upper layer film;

a second resist removal process to selectively remove the second region;

a second etching process of etching the semi-transmissive film, the upper layer film, and the intermediate film;

It is characterized in that it includes a process of removing the third area.

In addition, the method for manufacturing a photomask according to the present invention,

The semi-permeable film and the upper layer film are characterized in that they are made of the same material.

In addition, the method for manufacturing a photomask according to the present invention,

In the exposure process, the exposure amount of the first area is greater than that of the second area, and the exposure amount of the third area is 0.

With this photomask manufacturing method, a pattern made of a semi-transmissive film and a pattern made of a semi-transmissive film, an intermediate film, and an upper layer can be formed by suppressing the occurrence of overlap errors during exposure, and the photomask manufacturing process period. can contribute to shortening.

In addition, pattern design is possible without considering the overlap margin, enabling detailed pattern formation and reducing the designer's work burden.

Additionally, it can contribute to cost reduction in the manufacturing process.

In addition, the method for manufacturing a photomask according to the present invention,

The semi-permeable membrane is characterized in that it is a halftone membrane.

By using this photomask manufacturing method, a halftone mask, which is a multi-gradation mask, can be manufactured.

The method for manufacturing a photomask according to the present invention is,

The semi-transmissive film is characterized in that it is a phase shift film.

By using this photomask manufacturing method, a phase shift mask can be manufactured.

B. The Second Sun

The method for manufacturing a photomask according to the present invention is,

A process of preparing a photomask blank having a lower layer film on a transparent substrate and an upper layer film on the lower layer film;

A process of forming a resist film on the upper layer film;

an exposure step of exposing the resist film to form a first region, a second region, and a third region with different exposure amounts;

a first resist removal process for selectively removing the first region;

a first etching process of etching the upper layer film and the lower layer film;

a second resist removal process to selectively remove the second region;

a second etching process of etching the upper layer film;

It is characterized in that it includes a process of removing the third area.

In addition, the method for manufacturing a photomask according to the present invention,

The lower layer film and the upper layer film are characterized in that they are made of different materials.

In addition, the method for manufacturing a photomask according to the present invention,

In the exposure process, the exposure amount of the first area is greater than that of the second area, and the exposure amount of the third area is 0.

With this photomask manufacturing method, a pattern made of a lower layer film and a pattern made of a lower layer film and an upper layer film can be formed while suppressing the occurrence of overlap errors during exposure. Pattern design is possible without considering overlapping margins, detailed patterns can be formed, and the designer's work burden can be reduced.

Additionally, it can contribute to cost reduction in the manufacturing process.

In addition, the method for manufacturing a photomask according to the present invention,

The lower layer film is characterized in that it is a halftone film.

By using this photomask manufacturing method, a halftone mask, which is a multi-gradation mask, can be manufactured.

In addition, the method for manufacturing a photomask according to the present invention,

The lower layer film is characterized in that it is a phase shift film.

By using this photomask manufacturing method, a phase shift mask can be manufactured.

According to the first and second aspects, in any case, it is possible to provide a photomask manufacturing method capable of forming patterns with different optical characteristics by suppressing the occurrence of overlap errors during exposure.

Figure 1 is a cross-sectional view showing the main manufacturing process of a photomask.
Figure 2 is a cross-sectional view showing the main manufacturing process of a photomask.
Figure 3 is an SEM photograph showing a cross section of a photoresist film.
Figure 4 is a cross-sectional view showing the main manufacturing process of a photomask.
Figure 5 is a cross-sectional view showing the main manufacturing process of the photomask in Embodiment 2.
Figure 6 is a cross-sectional view showing the main manufacturing process of the photomask in Embodiment 2.
Figure 7 is a cross-sectional view showing the main manufacturing process of the photomask in Embodiment 1.
Figure 8 is a cross-sectional view showing the main manufacturing process of the photomask in Embodiment 1.
Figure 9 is an SEM photograph showing a cross section of a photoresist film.
Figure 10 is a cross-sectional view showing the main manufacturing process of the photomask in Embodiment 1.
Figure 11 is a cross-sectional view showing the main manufacturing process of the photomask in Embodiment 2.
Figure 12 is a cross-sectional view showing the main manufacturing process of the photomask in Embodiment 2.

Below, embodiments of the present invention will be described with reference to the drawings. However, the following embodiments do not give a limited interpretation in acknowledging the gist of the present invention. Additionally, identical or similar members may be given the same reference numerals and descriptions may be omitted.

(Embodiment 1)

1 and 2 are cross-sectional views showing the main manufacturing process of the photomask 100 according to Embodiment 1.

Hereinafter, a method of manufacturing the photomask 100 will be described with reference to the drawings.

(Film formation process: photomask blank preparation process)

As shown in FIG. 1(a), a transparent substrate 1 such as synthetic quartz glass is prepared, and a known substance such as a Cr-based metal compound, a Si-based compound, or a metal silicide compound is placed on the transparent substrate 1. A semi-permeable functional film 2 (semi-permeable film) made of a material is formed by sputtering, vapor deposition, etc.

Here, the transparent substrate 1 is 90 to 100% (90%) of the representative wavelengths (e.g., i-line, h-line, g-line) included in the exposure light used in the lithography process using the photomask 100. Transmittance It has a transmittance of 100%).

In addition, semi-transmittance means that the transmittance for representative wavelengths included in the exposure light is lower than the transmittance of the transparent substrate 1 and higher than the transmittance of the laminated structure film described later.

Additionally, the exposure light may be, for example, i-line, h-line, or g-line, or may be a mixed light containing at least two of these lights. Additionally, the exposure light is not limited to these.

The functional film 2 can be used as a halftone film or a phase shift film.

For example, when the functional film 2 is used as a halftone film, the transmittance of the functional film 2 is 10 to 70% (10%) for a representative wavelength. Transmittance Set it to 70%). Additionally, the phase shift amount can be set small (approximately 0°, for example, 0 to 20°).

In addition, for example, when the functional film 2 is used as a phase shift film, the transmittance of the functional film 2 is 3 to 15% (3%) with respect to the representative wavelength included in the exposure light. Transmittance 15%), the amount of phase shift is approximately 180° (160° phase shift amount 200°), more preferably 170° phase shift amount Set it to 190°.

The optical properties of the functional film 2 as a halftone film and a phase shift film can be realized by, for example, adjusting the composition and film thickness.

Next, the etching stopper film 3 (intermediate film 3) is formed by sputtering, vapor deposition, etc. (for example, with a film thickness of 1 nm to 20 nm).

Next, the light-shielding film 4 (upper layer film) is formed by sputtering, vapor deposition, etc. (for example, with a film thickness of 50 nm to 100 nm).

As will be described later, the etching stopper film 3 is made of a material that has different etching characteristics (having resistance) from the light-shielding film 4 (upper layer film) and the functional film 2.

In addition, if the laminated film consisting of the functional film 2, the etching stopper film 3, and the light-shielding film 4 has light-shielding properties, the light-shielding film 4 (upper layer film) does not need to be a single-layer light-shielding film having light-shielding properties. From this point of view, the material (composition) and film thickness of the light-shielding film 4 can be adjusted. The transmittance of this laminated film for a representative wavelength is, for example, 1% or less. In other words, the material (composition) and film thickness of the light-shielding film (4) can be adjusted in the laminated area of the functional film (2), the etching stopper film (3), and the light-shielding film (4) to ensure that the optical density OD value satisfies 3.0 or more. .

Hereinafter, a laminated structure in which a functional film (2), an etching stopper film (3), and a light-shielding film (4) are formed on a transparent substrate (1) is referred to as a photomask blank.

You may prepare and store a plurality of photomask blanks of the above configuration in advance. When an order is placed from a customer, etc., using a photomask blank of the above configuration that has been prepared in advance can contribute to shortening the process period.

(Photoresist formation process)

Next, as shown in FIG. 1(b), a (photo)resist film 5 is formed on the light shielding film 4 by a coating method, a spray method, or the like.

(Exposure process)

Next, as shown in FIG. 1(c), the photomask blank is loaded (placed on the exposure stage in the exposure device) into an exposure (drawing) device, such as laser drawing, and the resist film 5 is exposed. do.

At this time, the resist film 5 has three regions with different exposure amounts, namely, a high-dose region 5c (first region) and a low-dose region 5b ( A second area) and an unexposed area 5a (a third area) are formed.

Here, the unexposed area 5a is an area that is not exposed, that is, an area with an exposure amount of 0, the low dose area 5b is an area exposed with a relatively low exposure amount relative to the high dose area, and the high dose area 5c ) is an area exposed with a relatively high exposure amount compared to the low dose area.

The drawing method using the exposure device is not limited to laser drawing. For example, exposure may be performed using an electron beam.

More specifically, the high dose in the high dose region means an exposure amount greater than that required to dissolve the resist when the resist is removed in the first developing process described later. On the other hand, the low dose in the low dose area means that the resist is not removed in the first developing process, which will be described later, and is left behind, so that it is removed in the second developing process. For example, when based on the high dose required for the first development process, it means an exposure amount in the range of 5% to 90% of the high dose.

Although the low dose amount can be appropriately set within the above range, it goes without saying that the process time of the second development process needs to be taken into consideration.

Additionally, for convenience, the high dose region 5c of the resist film 5 is referred to as “high dose region 5c”, the low dose region 5b of the resist film 5 is referred to as “low dose region 5b”, and the resist film ( The unexposed area 5a in 5) may be referred to as “unexposed area 5a.”

The low dose region 5b and the high dose region 5c can be formed without unloading (taking out) the transparent substrate 1 from the exposure apparatus. For example, the area corresponding to the low dose area 5b and the area corresponding to the high dose area 5c are exposed by scanning the laser to the first exposure amount and the second exposure amount, respectively, and these areas are exposed. can be formed.

Additionally, the areas corresponding to the low dose area 5b and the high dose area 5c are exposed by scanning the laser to a first exposure amount, and then the high dose area 5c is exposed to a second exposure amount. Only the area corresponding to the high dose area 5c may be exposed by additionally scanning the laser. The exposure amount is averaged through multiple laser irradiations, thereby improving the uniformity of the exposure amount in the high dose area 5c. Additionally, when the low dose area 5b and the high dose area 5c are in contact, the uniformity of exposure amount in the boundary area is also improved.

Since the exposure process of the low dose area 5b and the high dose area 5c is performed without unloading the photomask blank from the exposure apparatus, the occurrence of overlap errors (misalignment) between these areas (patterns) is suppressed.

(First development (resist removal) process)

Next, as shown in FIG. 1(d), in the first development process, only the resist film 5 in the high dose area 5c is selectively removed with a developer to pattern the resist film 5.

As will be described later, since the dissolution characteristics of the resist film 5 by the developer depend on the exposure amount (dose amount), it becomes possible to selectively and sequentially remove the exposed resist film 5 according to the exposure amount. In the first development process, the dissolution rate of the high-dose region 5c is sufficiently increased (for example, several times to about 10 times or more) relative to the dissolution rate of the unexposed region 5a and the low-dose region 5b. By performing development (dissolution with developer) under these conditions, only the high dose area 5c can be selectively removed.

Additionally, as shown in Fig. 1(d), the resist film thickness in the low dose area 5b becomes thinner compared to the resist film thickness in the unexposed area 5a.

(First etching process)

Next, as shown in FIG. 2(a), the light-shielding film 4 is formed using the patterned resist film 5, that is, the resist film 5 in the unexposed area 5a and the low dose area 5b as an etching mask. ) is etched using a wet etching method or a dry etching method. The light-shielding film 4 and the etching stopper film 3 are made of different materials, and the light-shielding film on the etching stopper film 3 is formed using an etchant (chemical solution or gas) in which the etching stopper film 3 is not etched. (4) can be selectively etched. As a result, the etching stopper film 3 and its underlying functional film 2 are not etched and remain on the transparent substrate 1.

Since the functional film 2 whose surface is covered with the etching stopper film 3 is not etched in this process, the functional film 2 and the light-shielding film 4 can be constructed using the same material.

In this case, the same film formation device or the same film formation material (sputtering target, deposition material) can be used in the film formation process of the functional film 2 and the light shielding film 4, and the etching of the functional film 2 and the light shielding film 4 may also be performed. Since the same etching device or the same etchant can be used in the process, production management is easy and manufacturing costs are reduced.

Next, as shown in FIG. 2(b), the etching stopper film 3 is wet etched or dry etched using the resist film 5 in the unexposed area 5a and the low dose area 5b as an etching mask. Etch by law. The functional film (2) and the etching stopper film (3) are made of different materials, and an etchant (chemical solution or gas) that does not etch the functional film (2) is used to form the etching stopper film (3) on the functional film (2). ) can be selectively etched. As a result, the functional film 2 is not etched, but remains on the transparent substrate 1.

(Second development (resist removal) process)

Next, as shown in FIG. 2(c), in the second development process, only the resist film 5 in the low dose region 5b is selectively removed with a developing solution to pattern the resist film 5. In this process, only the unexposed area 5a is left on the light shielding film 4.

As shown in the first development process and the second development process, the resist film 5 with different exposure amounts can be sequentially removed depending on the exposure amount because the dissolution rate depends nonlinearly on the development conditions (time, etc.). am. Using the characteristic that the change point at which the dissolution rate changes (increases) varies depending on the exposure amount, areas with different exposure amounts can be selectively removed sequentially.

In the second development process, development (dissolution) is performed under developing conditions in which the dissolution rate of the low-dose region 5b is sufficiently high compared to the dissolution rate of the unexposed region 5a to selectively remove only the low-dose region 5b. You can.

Additionally, by using this method, it is also possible to obtain three or more different patterns of the resist film 5.

(Second etching process)

Next, as shown in FIG. 2(d), the functional film 2 is removed by etching by a wet etching method or a dry etching method, and a light-shielding film is formed using the resist film 5 in the unexposed area 5a as an etching mask. (4) is removed by etching using a wet etching method or a dry etching method. In the area where the functional film 2 is etched, the transparent substrate 1 is exposed.

By constructing the functional film 2 and the light-shielding film 4 from the same material, the functional film 2 and the light-shielding film 4 can be etched simultaneously using the same etchant.

Thereafter, the etching stopper film 3 is removed by etching using a wet etching method or a dry etching method.

Thereafter, the resist film 5 in the unexposed area 5a is removed by ashing or immersion in a resist stripper (third resist removal process).

Above, a semi-transmissive region 6 composed of a functional film 2, a light-shielding region composed of a laminated layer including the functional film 2 as the lower layer, the etching stopper film 3 as the middle layer, and the light-shielding film 4 as the upper layer. (7), and a photomask 100 having a transparent area 8 where the transparent substrate 1 is exposed can be obtained.

The photomask 100 functions as a multi-gradation halftone mask by adopting the conditions of the halftone film as the functional film 2, and functions as a phase shift mask by adopting the conditions of the phase shift film as the functional film 2. It functions.

In addition, after selectively etching the etching stopper film 3 on the functional film 2 in the process shown in FIG. 2(b), the functional film 2 may be further etched.

However, in this case, if the light-shielding film 4 is etched using, for example, isotropic etching such as wet etching in the second etching process shown in FIG. 2(d), the functional film 2 is also etched, resulting in the functional film ( 2) The amount of side etching increases.

In the process shown in FIG. 2(b), only the light shielding film 4 and the etching stopper film 3 are etched to leave the functional film 2, so that the side of the functional film 2 in the process shown in FIG. 2(d) is etched. The etching amount can be reduced. As a result, the patterning controllability of the functional film 2 is improved.

Figure 3 is an SEM photograph showing the cross-sectional shape of the photoresist. FIG. 3(a) shows the cross-sectional shape of the resist film 5 after the first developing process, and FIG. 3(b) shows the cross-sectional shape of the resist film 5 after the second developing process.

As shown in FIG. 3(a), the cross section of the resist film 5 may have a gently tapered shape at the boundary where the unexposed area 5a and the low dose area 5b meet.

However, as shown in Fig. 3(b), after the second development process, the cross section of the resist film 5 in the unexposed area 5a shows a very steep shape. That is, it shows that the resist film 5 in the low dose region 5b, which was determined in the exposure process shown in FIG. 1(c), was selectively removed in the second development process.

If the resist film 5 is uniformly dissolved in the second development process, the cross-section of the resist film 5 in the unexposed area 5a cannot obtain a very steep shape as shown in FIG. 3(b). does not exist.

When the side wall of the resist film 5 in the unexposed area 5a with a thick film thickness is tapered, the pattern width varies, making it difficult to form a fine pattern.

In particular, since the film thickness of the resist film 5 in the unexposed area 5a is thicker than that in the low dose area 5b, the taper angle of the cross section of the unexposed area 5a is formed on the photomask 100. The impact on pattern precision increases. However, by controlling the exposure amount and optically determining the boundary between the low dose area 5b and the unexposed area 5a, the lateral shape of the resist film 5 in the unexposed area 5a after the second development process is changed. As shown in Figure 3(b), it becomes very steep. As a result, precise pattern formation is possible through lithography using the present photomask 100.

1 and 2 show an example in which the semi-transmissive region 6 and the light-shielding region 7 are in contact with each other, but since the shape of the photoresist film 5 can be optically determined in the exposure process, the photoresist film ( 5) can be patterned into a desired shape.

For example, as shown in FIG. 4(c), it is also possible to form the semi-transmissive area 6 and the light-blocking area 7 to be spaced apart from each other. As shown in FIG. 4(a), the unexposed area 5a and the low dose area 5b are exposed to the resist film 5 by an exposure (drawing) device at a distance from each other, and then, in FIG. 4(b) ), the resist film 5 in the unexposed area 5a and the resist film 5 in the low dose area 5b that are spaced apart from each other can be obtained through the first development process.

After that, it is also possible to form the semi-transmissive area 6 and the light-shielding area 7 spaced apart from each other through the process shown in FIG. 2. Accordingly, the degree of freedom in designing the pattern of the photomask 100 is greatly improved compared to the method disclosed in Patent Document 1.

In addition, it is also possible to arrange a pattern in which a pattern in which the semi-transmissive area 6 and the light-shielding area 7 are spaced apart from each other and a pattern in which the semi-transmissive area 6 and the light-shielding area 7 are adjacent to each other are mixed.

(Embodiment 2)

The photomask 100 can also be manufactured using the following manufacturing process described with reference to FIGS. 5 and 6 .

As shown in Fig. 5(a), a semi-transmissive functional film 2 (semi-transmissive film) made of a metal compound, for example, a Cr compound, is formed on the transparent substrate 1 by sputtering, vapor deposition, or the like.

As described above, the functional film 2 can be used as a halftone film or a phase shift film.

Next, a light-shielding film 41 is formed on the functional film 2 by sputtering, vapor deposition, or the like.

The light-shielding film 41 is made of a different type of metal (or a compound thereof) from the metal compound constituting the functional film 2. For example, the functional film 2 can be made of a Cr compound, and the light-shielding film 41 can be made of a Ni film.

The film thickness of the light-shielding film 41 to be formed is set so that the optical density (OD value) is 3 or more. For example, when Ni is used as the light-shielding film 41, the film thickness can be, for example, 100 nm.

Next, an antireflection film 9 made of a metal compound is formed on the light shielding film 41 by sputtering, vapor deposition, etc. The thickness of the anti-reflection film 9 can be, for example, 2 to 5 nm. The anti-reflection film 9 is made of a metal compound, such as metal oxide, metal nitride, or metal oxynitride. The metal of the metal compound constituting the anti-reflection film 9 and the metal of the metal compound constituting the functional film 2 are made of the same type of metal. That is, the metal component constituting the functional film 2 and the metal component constituting the antireflection film 9 are composed of the same metal element. For example, when the functional film 2 is made of a compound containing Cr, the anti-reflection film 9 is also made of a compound containing Cr.

Additionally, as the Cr compound, Cr oxide, Cr nitride, and Cr nitrogen oxide can be used, for example.

Next, a (photo)resist film 5 is formed on the anti-reflection film 9 by a coating method, a spray method, or the like.

Accordingly, on the transparent substrate 1, the functional film 2, light-shielding film 41, anti-reflection film 9 and resist film 5 are formed in this order.

Next, as shown in Fig. 5(b), the resist film 5 is patterned in the same process as the process shown in Figs. 1(c) and 1(d) to form two regions with different exposure amounts, that is, the low dose region ( 5b) (second area) and an unexposed area 5a (third area) are formed.

The anti-reflection film 9 can improve the patterning precision of the resist film 5 by reducing unnecessary reflection (halation, etc.) of exposure light during exposure of the resist film 5.

Next, as shown in FIG. 5(c), wet etching is performed using the low dose area 5b (second area) and the unexposed area 5a (third area) of the resist film 5 as a mask. The anti-reflection film 9 is selectively etched with respect to the light-shielding film 41 using a mechanical or dry etching method.

As described above, since the light-shielding film 41 is made of a different type of metal from the metal of the metal compound constituting the anti-reflection film 9, the etching rate of the light-shielding film 41 is low and the etching of the light-shielding film 41 is low. By employing an etchant (chemical solution or gas) with a high etching selectivity for the anti-reflection film 9, it is possible to selectively etch only the anti-reflection film 9 without etching the light-shielding film 41.

Additionally, in this process, the functional film 2 is not etched because its surface is covered with the light-shielding film 41.

Additionally, as the etching device and etchant, known etching devices and etchants capable of selective etching may be appropriately used. The same applies below.

Next, as shown in FIG. 5(d), wet etching is performed using the low dose area 5b (second area) and the unexposed area 5a (third area) of the resist film 5 as a mask. The light-shielding film 41 is selectively etched with respect to the anti-reflective film 9 and the functional film 2 using a dry etching method. Since the anti-reflection film 9 and the functional film 2 are composed of a compound of a metal different from the metal constituting the light-shielding film 41, the etching rate of the anti-reflection film 9 and the functional film 2 is low and the anti-reflection film 41 has a low etching rate. (9) and by employing an etchant (chemical solution or gas) with a high etching selectivity of the light-shielding film 41 to etching of the functional film 2, the etching rate of the anti-reflection film 9 and the functional film 2 is suppressed low. While doing so, only the light shielding film 41 can be selectively etched.

Generally, in the case of wet etching, when the upper layer light-shielding film 41 is selectively etched, damage to the lower layer functional film 2 (film reduction, ion impact due to dry etching, etc.) tends to be reduced. Therefore, the wet etching method can be suitably used in terms of avoiding damage to the functional film 2.

Next, as shown in FIG. 5(e), wet etching is performed using the low dose area 5b (second area) and the unexposed area 5a (third area) of the resist film 5 as a mask. The functional film 2 is selectively etched with respect to the light-shielding film 41 using a dry etching method. Similar to the selective etching of the anti-reflection film 9 described above, the light-shielding film 41 is made of a metal different from the metal of the metal compound constituting the functional film 2, and the functional film 2 for etching of the light-shielding film 41 Since an etchant (chemical solution or gas) with a high etching selectivity ratio can be employed, only the functional film 2 can be selectively etched using an etchant in which the light-shielding film 41 is not etched.

However, the anti-reflection film 9 and the functional film 2 are metal compounds composed of the same type of metal, and in the case of isotropic etching, especially wet etching, the anti-reflection film 9 is used as an etchant to etch the functional film 2. ) can be side-etched.

However, the film thickness of the anti-reflection film 9 is thinner than the film thickness of the functional film 2. For example, the film thickness of the anti-reflection film 9 is (but is not limited to) about one-fifth of the film thickness of the functional film 2 to about one-tenth the film thickness of the functional film 2. It can be set to a film thickness of . Therefore, compared to the functional film 2, the height of the side wall surface where the anti-reflective film 9 is exposed is lower, the exposed area is small, and the amount of side etching of the anti-reflective film 9 is reduced.

Therefore, even if the etchant used in the etching process for the anti-reflection film 9 in Fig. 5(c) is the same as the etchant for the functional film 2 in this process, the side etching amount of the anti-reflection film 9 (The amount of retreat due to side etching) decreases.

thus. It is also possible to use the same etchant (chemical solution) with the same etching device (wet etching device).

In this process, the anti-reflection film 9 does not prevent etching of the functional film 2 using an etchant (chemical solution or gas) that does not etch. However, as described above, using the same etching device and the same etchant in the etching process of the anti-reflection film 9 and the etching process of the functional film 2 has the effect of reducing the operating cost of the etching device and/or the etchant. can be obtained.

Next, as shown in FIG. 6(a), in the same manner as the process shown in FIG. 2(c), only the resist film 5 in the low dose area 5b is selectively removed to reflect only the unexposed area 5a. Leave it on the barrier (9).

Next, as shown in FIG. 6(b), the unexposed area 5a of the resist film 5 is used as a mask, and the anti-reflection film 9 is applied to the light-shielding film 41 in the same manner as the process shown in FIG. 5(c). ) is selectively etched.

When etching the anti-reflective film 9, the functional film 2 may be side-etched. However, since the film thickness of the anti-reflection film 9 is sufficiently thin compared to the functional film 2, the amount of etching of the anti-reflection film 9 is small. Therefore, in this process of etching the anti-reflection film 9, even when an etchant is used to etch both the anti-reflection film 9 and the functional film 2, the amount of side etching of the functional film 2 is small, and the functional film 2 is Reduction of the pattern width of the film 2 is reduced.

In addition, this process does not prevent the anti-reflection film 9 from being etched using an etchant (chemical solution or gas) that does not etch both the light-shielding film 41 and the functional film 2. However, when etching the anti-reflective film 9 as described above, the effect on the pattern dimensions due to the side etching of the functional film 2 is slight, and deterioration of dimensional accuracy can be prevented. Therefore, in the etching process of the anti-reflection film 9 (process shown in FIGS. 5(c) and 6(b)) and the etching process of the functional film 2 (process shown in FIG. 5(e)), the same Using an etchant can contribute to reducing the operating costs of the etching process (including, for example, the management cost of the etchant).

Additionally, this does not prevent the use of a dry etching method as an etching method. However, compared to a dry etching device, a wet etching device does not require a vacuum chamber or exhaust equipment, is easy to manufacture a large-area photomask 100, and is generally inexpensive. According to the present embodiment, the pattern dimensional accuracy of the functional film 2 can be easily secured even if a wet etching method, which is an etching method with strong isotropy, is adopted, and thus the manufacturing cost is reduced by using a wet etching device as the etching device. The effect is great.

Next, as shown in FIG. 6(c), in the same manner as the process shown in FIG. 5(d), the unexposed area 5a of the resist film 5 is used as a mask, and the light-shielding film 41 is applied to the anti-reflection film 9. ) and selectively etching the functional film (2).

Next, as shown in FIG. 6(d), the resist film 5 in the unexposed area 5a is removed by painting or immersing in a resist stripper to obtain the photomask 100.

In this embodiment, the light-shielding film 41 is made of a film having etching characteristics different from those of the functional film 2 and the anti-reflection film 9, and the film thickness of the anti-reflection film 9 is equal to the film thickness of the functional film 2. Since it is set thin compared to , side etching of the functional film 2 is reduced and it becomes easy to secure the dimensional accuracy of the functional film 2.

Therefore, the dimensional accuracy required for the final product manufactured by using the photomask 100 in a lithography process can be easily secured.

Moreover, even if the antireflection film 9 and the functional film 2 are etched using the same etching device, good processing accuracy can be achieved. As a result, an effect contributing to reduction of manufacturing costs can be obtained. In particular, when a wet etching device is used as the etching device, the effect is great.

In addition, although the above embodiment has been described as an example of using a positive resist as the resist film 5, the same applies to the case of using a negative resist. In the case of negative resist, the relationship between exposure amounts is opposite to that of positive resist. The unexposed area of the positive resist corresponds to the high dose area of the negative resist, and the high dose area of the positive resist corresponds to the unexposed area of the negative resist.

(Embodiment 3)

7 and 8 are cross-sectional views showing the main manufacturing process of the photomask 100 according to Embodiment 3. Hereinafter, a method of manufacturing the photomask 100 will be described with reference to the drawings.

(Film formation process: photomask blank preparation process)

As shown in FIG. 7(a), a transparent substrate 11 such as synthetic quartz glass is prepared, and a known substance such as a Cr-based metal compound, a Si-based compound, or a metal silicide compound is placed on the transparent substrate 11. A semi-transparent lower layer film 12 made of a material is formed by sputtering, vapor deposition, etc. (for example, 5 nm to 20 nm thick).

Here, the transparent substrate 11 has 90 to 100% (90%) of the representative wavelengths (e.g., i-line, h-line, and g-line) included in the exposure light used in the lithography process using the photomask 100. Transmittance It has a transmittance of 100%).

In addition, semi-transmittance means that the transmittance for representative wavelengths included in the exposure light is lower than the transmittance of the transparent substrate 11 and higher than the transmittance of the laminated structure film described later.

Additionally, the exposure light may be, for example, i-line, h-line, or g-line, or may be a mixed light containing at least two of these lights. Additionally, the exposure light is not limited to these.

The lower layer film 12 can be used as a halftone film or a phase shift film.

For example, when using the lower layer film 12 as a halftone film, the transmittance of the lower layer film 12 is 10 to 70% (10%) for a representative wavelength. Transmittance Set it to 70%). Additionally, the phase shift amount can be set small (approximately 0°, for example, 0 to 20°).

In addition, for example, when the underlayer film 12 is used as a phase shift film, the transmittance of the underlayer film 12 is 3 to 15% (3%) with respect to the representative wavelength included in the exposure light. Transmittance 15%), the amount of phase shift is approximately 180° (160° phase shift amount 200°), more preferably 170° phase shift amount Set it to 190°.

The optical properties of the lower layer film 12 as a halftone film and a phase shift film can be realized by, for example, adjusting the composition and film thickness.

Next, an upper layer film 13 made of a known material such as, for example, a Cr-based metal compound, a Si-based compound, or a metal silicide compound is deposited on the lower layer film 12 by sputtering, vapor deposition, etc. Form a film with a thickness of 50 nm to 100 nm. However, the upper layer film 13 is made of a material that has different etching characteristics from the lower layer film 12. For example, a combination of a Cr-based compound as the lower layer film 12 and a metal-based compound other than Cr, such as a Ti-based compound or a Ni-based compound, is selected as the upper layer film 13. Additionally, metal compounds such as Cr-based compounds may be composed of only metal.

The transmittance of the upper layer film 13 for representative wavelengths can be determined by adjusting the material (composition) and film thickness of the upper layer film 13 so that the laminated film of the upper layer film 13 and the lower layer film 12 has light blocking properties. The transmittance for representative wavelengths of this laminated film is, for example, 1% or less (0% Transmittance 1%). In other words, the optical density (OD value) satisfies 3.0 or more by adjusting the material (composition) and film thickness of the light-shielding film (4) in the laminated area of the functional film (2), the etching stopper film (3), and the light-shielding film (4). Just do it.

Hereinafter, the laminated structure in which the lower layer film 12 and the upper layer film 13 are formed on the transparent substrate 11 is referred to as a photomask blank.

You may prepare and store a plurality of photomask blanks of the above configuration in advance. When an order is placed from a customer, etc., the use of a photomask blank of the above configuration that has been prepared in advance can contribute to shortening the process period.

(Photoresist formation process)

Next, as shown in FIG. 7(b), a (photo)resist film 14 is formed on the upper layer film 13 by a coating method, a spray method, or the like.

(Exposure process)

Next, as shown in FIG. 7(c), the photomask blank is loaded into an exposure (drawing) device (for example, a laser drawing device) (placed on an exposure stage in the exposure device) to form a resist film 14. expose.

At this time, the resist film 14 has three areas with different exposure amounts, namely, the high dose area 14c (first area), the low dose area 14b (second area), and the unexposed area 14a. (Third area) is formed.

Here, the unexposed area 14a is an area that is not exposed, that is, an area with an exposure amount of 0, the low dose area 14b is an area exposed with a relatively low exposure amount, and the high dose area 14c is an area with a relatively high exposure amount. This is the area exposed with the exposure amount.

The drawing method using the exposure device is not limited to laser drawing. For example, you can use electron beams.

More specifically, the high dose in the high dose region means an exposure amount greater than that required to dissolve the resist when the resist is removed in the first developing process described later. On the other hand, the low dose in the low dose area means that the resist is not removed in the first developing process, which will be described later, and is an exposure amount that is enough to be removed in the second developing process. For example, when based on the high dose required for the first development process, it means an exposure amount in the range of 5% to 90% of the high dose.

Although the low dose amount can be appropriately set within the above range, it goes without saying that the process time of the second development process needs to be taken into consideration.

In addition, for convenience, the high dose region 14c of the resist film 14 is referred to as “high dose region 14c”, the low dose region 14b of the resist film 14 is referred to as “low dose region 14b”, and the resist film ( The unexposed area 14a of 14) may be referred to as the “unexposed area 14a”.

The low dose region 14b and the high dose region 14c can be formed without unloading (taking out) the transparent substrate 11 from the exposure apparatus. For example, the area corresponding to the low dose area 14b and the area corresponding to the high dose area 14c are exposed by scanning the laser to the first exposure amount and the second exposure amount, respectively, and these areas are exposed. can be formed.

Additionally, the regions corresponding to the low dose region 14b and the high dose region 14c are exposed by scanning the laser to a first exposure dose, and then the high dose region 14c is exposed to a second exposure dose. Only the area corresponding to the high dose area 14c may be exposed by additionally scanning the laser. The exposure amount is averaged by irradiating multiple lasers, and the uniformity of the exposure amount in the high dose area 14c is improved. Additionally, when the low dose area 14b and the high dose area 14c are in contact, the uniformity of exposure amount in the boundary area is also improved.

As described above, since the exposure process of the low dose area 14b and the high dose area 14c is performed without unloading the photomask blank from the exposure apparatus, the occurrence of overlap error (misalignment) between these areas (patterns) It is suppressed.

(First development (resist removal) process)

Next, as shown in FIG. 7(d), in the first development process, only the resist film 14 in the high dose area 14c is selectively removed with a developer to pattern the resist film 14.

As will be described later, since the dissolution characteristics of the resist film 14 by the developer depend on the exposure amount (dose), it becomes possible to selectively and sequentially remove the exposed resist film 14 according to the exposure amount. In the first development process, development conditions are such that the dissolution rate of the high-dose region 14c is sufficiently high (for example, several times to about 10 times) relative to the dissolution rate of the unexposed region 14a and the low-dose region 14b. By performing development (dissolution using a developer), only the high dose area 14c can be selectively removed.

Additionally, as shown in FIG. 7(d), the resist film thickness of the low dose area 14b becomes thinner compared to the resist film thickness of the unexposed area 14a.

(First etching process)

Next, as shown in FIG. 8(a), the patterned resist film 14, that is, the resist film 14 in the unexposed area 14a and the low dose area 14b, is used as an etching mask, and the upper layer film is etched. (13) is etched by a wet etching method or a dry etching method, and then the underlayer film 12 is etched by a wet etching method or a dry etching method to expose the surface of the transparent substrate 11.

By using different materials for the upper layer film 13 and the lower layer film 12, the upper layer film 13 can be selectively etched using an etchant (chemical solution or gas) that does not etch the lower layer film 12. . Thereafter, the lower layer film 12 can be selectively etched using an etchant (chemical solution or gas) that does not etch the upper layer film 13.

(Second development (resist removal) process)

Next, as shown in FIG. 8(b), in the second development process, only the resist film 14 in the low dose region 14b is selectively removed with a developing solution to pattern the resist film 14. In this process, only the unexposed area 14a is left on the upper layer film 13.

As shown in the first development process and the second development process, the resist film 14 with different exposure amounts can be removed sequentially depending on the exposure amount, a phenomenon in which the dissolution rate depends nonlinearly on the development conditions (time, etc.). Because there is this. Using the characteristic that the change point at which the dissolution rate changes (increases) varies depending on the exposure amount, areas with different exposure amounts can be selectively removed sequentially.

In the second development process, development (dissolution) is performed under developing conditions in which the dissolution rate of the low-dose region 14b is sufficiently high relative to the dissolution rate of the unexposed region 14a to selectively remove only the low-dose region 14b. You can.

Additionally, by using this method, it is also possible to obtain three or more different patterns of the resist film 14.

(Second etching process)

Next, as shown in FIG. 8(c), using the unexposed area 14a as an etching mask, the upper layer film 13 is etched using an etchant (chemical solution or gas) that does not etch the lower layer film 12. Selectively etch using a wet etching method or a dry etching method.

In FIG. 8(c), a pattern composed of only the lower layer film 12 is formed on both sides of a pattern composed of a stack of the lower layer film 12 and the upper layer film 13.

Since the pattern consisting of only the underlayer film 12 is determined by the low dose region 14b, it can be optically set in the exposure process shown in FIG. 7(c).

(Third resist removal process)

Next, as shown in FIG. 8(d), the resist film 14 in the unexposed area 14a is removed by painting or immersion in a resist stripper.

As described above, the light-shielding area 15 composed of a stack including the lower layer film 12 and the upper layer film 13, the semi-transmissive region 16 composed of the lower layer film 12, and the transparent substrate 11 are exposed. A photomask 100 having a transmission area 17 can be obtained.

The photomask 100 functions as a multi-gradation halftone mask by employing the conditions of the halftone film as the lower layer film 12. In addition, the photomask 100 can function as a phase shift mask by employing the conditions of the phase shift film as the underlayer film 12. In particular, in this case, since the occurrence of overlap errors in the exposure process is suppressed, the rims of the semi-transmissive area 16 can be provided symmetrically on both sides of the light-shielding area 15, making it possible to form a detailed pattern. You can obtain a phase shift mask that allows you to do this.

Figure 9 is an SEM photograph showing the cross-sectional shape of the photoresist. FIG. 9(a) shows the cross-sectional shape of the resist film 14 after the first developing process, and FIG. 9(b) shows the cross-sectional shape of the resist film 14 after the second developing process.

As shown in FIG. 9(a), the cross section of the resist film 14 may have a gently tapered shape at the boundary where the unexposed area 14a and the low dose area 14b meet.

However, as shown in FIG. 9(b), after the second development process, the cross section of the resist film 14 in the unexposed area 14a shows a very steep shape. That is, the resist film 14 in the low dose area 14b determined in the exposure process shown in FIG. 7(c) is selectively removed in the second developing process, and the unexposed area 14a is optically accurately determined. It shows.

Additionally, as shown in FIG. 10(c), it is also possible to form the transflective area 16 and the light blocking area 15 to be spaced apart from each other. As shown in FIG. 10(a), the unexposed area 14a and the low dose area 14b are exposed to the resist film 14 with an exposure (drawing) device spaced apart from each other, and then, in FIG. 10(b) ), the unexposed area 14a and the low dose area 14b spaced apart from each other can be obtained through the first developing process.

Thereafter, through the process shown in FIG. 8, the semi-transmissive area 16 and the light-blocking area 15 can be formed to be spaced apart from each other.

Therefore, the light blocking area 15 and the semi-transmissive area 16 can be optically set to a desired pattern, and the degree of freedom in designing the pattern of the photomask 100 is greatly improved compared to the method disclosed in Patent Documents 1 and 2. .

In addition, it is also possible to arrange a pattern in which a pattern in which the semi-transmissive area 16 and the light-blocking area 15 are spaced apart from each other and a pattern in which the semi-transmissive area 16 and the light-blocking area 15 are adjacent to each other are mixed.

The fact that various arrangements of the patterns between the semi-transmissive area 16 and the light-shielding area 15 are possible as described above also applies to other embodiments.

(Embodiment 4)

In Embodiment 3, three types of regions, an unexposed region 14a, a low dose region 14b, and a high dose region 14c, are formed in the resist film 14 through a single exposure process, and a transmissive region and a semi-transmissive region are formed. It was shown that a photomask with three gradations of area and light blocking area can be manufactured.

According to Embodiment 4, it is also possible to provide a photomask 100 with more multi-gradation levels.

As shown in FIG. 11(a), the resist film 14 is exposed in one exposure process, and the first area 14d, the second area 14e, and the third area 14f are formed in order of increasing exposure amount. ), forming a fourth area 14g (exposure amount 0).

Next, as shown in FIG. 11(b), after selectively removing the first area 14d with the largest amount of exposure, the second area 14e, the third area 14f, and the fourth area Using the resist film 14 of (14g) as a mask, the upper layer film 13 and the lower layer film 12 are etched to expose the transparent substrate 11.

Next, as shown in FIG. 11(c), after selectively removing the second area 14e with the second largest exposure amount, the resist film in the third area 14f and the fourth area 14g is removed. The upper layer film 13 is removed by etching using (14) as a mask, and the lower layer film 12 is partially further etched to form a first lower layer film 12a with a relatively thin film thickness (thin lower layer film 12a). ) and a second lower layer film 12b (thick lower layer film 12b) with a relatively thick film thickness.

Next, as shown in FIG. 11(d), after selectively removing the third area 14f with the third largest amount of exposure, the upper layer layer is applied using the resist film 14 in the fourth area 14g as a mask. (13) is removed by etching to expose the surface of the second lower layer film 12b.

Next, as shown in FIG. 11(e), the resist film 14 in the fourth region 14g is removed by painting or immersing in a resist stripper.

A light blocking area 15 is a layer of the lower layer 12 and the upper layer 13, a transmission area 17 where the transparent substrate 11 is exposed, and a first lower layer 12a with a relatively thin film thickness. A first semi-transmissive region 161 and a second semi-transparent region 162 are formed with a relatively thick second lower layer 12b.

Accordingly, it is possible to obtain a photomask 100 with four gradations of the transmissive area 17 and the light-shielding area 15, and the first transmissive area 161 and the second transflective area 162 having different transmittances. .

Additionally, a semi-transmissive region may be formed by partially etching a portion of the upper layer film 13 to reduce the film thickness.

In the process shown in FIG. 11(c), after selectively removing the second area 14e with the second largest exposure amount, the resist film 14 in the third area 14f and the fourth area 14g is formed. In the same manner as the process shown in FIG. 8(c) using a mask, only the upper layer film 13 is selectively etched and removed to expose the surface of the lower layer film 12 (see FIG. 12(a)).

Next, as shown in FIG. 12(b), after selectively removing the third area 14f with the third largest amount of exposure, the upper layer layer is applied using the resist film 14 in the fourth area 14g as a mask. (13) is partially etched to form a first upper layer film 13a (thin upper layer film) with a relatively thin film thickness and a second upper layer film 13b with a relatively thick film thickness (thick upper layer film 13b). ) is formed.

The thin upper layer film 13a obtained by reducing the film thickness of the upper layer film 13 has increased transmittance for representative wavelengths and becomes a semi-transmissive film.

Next, as shown in FIG. 12(c), the resist film 14 in the fourth region 14g is removed by painting or immersing in a resist stripper.

A transparent region 17 in which the transparent substrate 11 is exposed, a first semi-transmissive region 161 composed of a lower layer film 12, and a first upper layer film ( A second semi-transmissive region 162 composed of a lamination of the lower layer 12 and a second upper layer 13b having a relatively thick film thickness is formed. . Since the second semi-transmissive region 162 is provided with the first upper layer film 13a (thin upper layer film) on the lower layer 12, the transmittance is higher than that of the first semi-transmissive region 161. It becomes low. In addition, because the first upper layer film 13a has a thinner film thickness than the upper layer film 13 and has increased transmittance, the second semi-transmissive region 162 is a light blocking region 15 (lower layer film 12 and the thick film). It becomes a semi-transmissive area with higher transmittance than the lamination with the upper layer film 13b.

Accordingly, a four-gradation photomask 100 is obtained, which includes a transmissive region 17, a first semi-transmissive region 161, a second semi-transmissive region 162, and a light-shielding region 15, each having a different transmittance. You can.

In this way, by reducing the film thickness in some areas of the lower layer film 12 or the upper layer film 13 to change the transmittance, it is possible to obtain a photomask 100 with more multi-gradation. In addition, by combining the manufacturing process shown in FIG. 11 and the manufacturing process shown in FIG. 12, the film thickness is reduced in some areas of the lower layer film 12 and the upper layer film 13 to change the transmittance, thereby producing a multi-gradation photomask ( 100) can also be obtained.

In addition, each of the above embodiments has been explained by taking the case of using a positive resist as the resist film 14 as an example, but the same applies to the case of using a negative resist. In the case of negative resist, the relationship between exposure amounts is opposite to that of positive resist. For example, the unexposed area of the positive resist corresponds to the high dose area of the negative resist, and the high dose area of the positive resist corresponds to the unexposed area of the negative resist.

According to the present invention, a photomask with patterns having different optical characteristics can be obtained through a single exposure treatment process. As a result, a fine pattern can be realized while preventing an increase in the number of photomask manufacturing processes.

By using this photomask in the production process of products such as display devices, it can contribute to improving product performance, etc., and has great potential for industrial use.

100 photomask
1 Permeable substrate
2 Functional membrane (semi-permeable membrane)
3 Etching stopper film (intermediate film)
4 Light shielding film (upper layer film)
5 (Photo) resist film
5a unexposed area
5b low-dose region
5c high-dose region
6 semi-transmissive region
7 Shading area
8 transmission area
9 Anti-reflective film
41 sunshade
11 Permeable substrate
12 Lower layer
12a First lower layer film (thin lower layer film)
12b Second lower layer film (thick lower layer film)
13 Upper layer
13a First upper layer film (thin upper layer film)
13b Second upper layer (thick upper layer)
14 (Photo) Resist Film
14a Unexposed area (third area)
14b low dose region (second region)
14c high dose region (first region)
14d first area
14e The Second Realm
14f The Third Realm
14g the fourth realm
15 shaded areas
16 semi-transmissive areas
161 First semi-transparent region
162 Second semi-transparent region
17 transmission area

Claims (21)

A process of preparing a photomask blank having a lower layer film on a transparent substrate and an upper layer film on the lower layer film;
Positive type on the upper layer A process of forming a resist film;
an exposure process of exposing the resist film to form a first region, a second region, and a third region all having different exposure amounts;
a first resist removal process for selectively removing the first region;
a first etching process of etching the upper layer film and the lower layer film;
a second resist removal process to selectively remove the second region;
a second etching process of selectively etching the upper layer film with respect to the lower layer film;
and a third resist removal process for removing the third region in this order,
In the exposure process,
The third area is an unexposed area,
The first area is exposed to a higher exposure amount than the second area,
The cross-sectional shape of the resist film of the edge portion of the third region after the second resist removal process is the boundary portion where the second region and the third region contact each other after the first resist removal process. A method of manufacturing a photomask, characterized in that the shape is steeper than the cross-sectional shape of the resist film.
According to claim 1,
A method of manufacturing a photomask, wherein the underlayer film is a semi-transmissive film with a transmittance of 10% to 70% and a phase shift amount of 0 degrees to 20 degrees.
According to claim 1,
A method of manufacturing a photomask, wherein the underlayer film is a phase shift film with a transmittance of 3% to 15% and a phase shift amount of 160 degrees to 200 degrees.
The method according to any one of claims 1 to 3,
A method of manufacturing a photomask, wherein the lower layer film and the upper layer film are composed of different materials.
The method according to any one of claims 1 to 3,
A method of manufacturing a photomask, wherein the transmittance of a laminated region of the lower layer film and the upper layer film is adjusted by adjusting the film thickness of the upper layer film.
The method according to any one of claims 1 to 3,
A method of manufacturing a photomask, wherein the upper layer film is a Cr-based metal compound, a Si-based compound, or a metal silicide compound.
The method according to any one of claims 1 to 3,
A method of manufacturing a photomask, wherein the underlayer film is a Cr-based metal compound, a Si-based compound, or a metal silicide compound.
The method according to any one of claims 1 to 3,
A method of manufacturing a photomask, wherein the transmittance of the upper layer film is adjusted by etching the upper layer film to adjust the film thickness of the upper layer film.
In the photomask manufactured according to any one of claims 1 to 3,
A pattern composed of the lower layer film on a transparent substrate and a pattern composed of a laminated film having an upper layer film on the lower layer film,
The lower layer film is a semi-transmissive film with a transmittance of 10% to 70% and a phase shift amount of 0 degrees to 20 degrees,
The material of the lower layer film is selected from Cr-based metal compounds, Si-based compounds, or metal silicide compounds,
A photomask wherein the material of the upper layer film is selected from a Cr-based metal compound, a Si-based compound, or a metal silicide compound and is different from the lower layer film.
In the photomask manufactured according to any one of claims 1 to 3,
A pattern composed of the lower layer film on a transparent substrate and a pattern composed of a laminated film having the upper layer film on the lower layer film,
The lower layer film is a phase shift film with a transmittance of 3% to 15% and a phase shift amount of 160 degrees to 200 degrees,
The material of the lower layer film is selected from Cr-based metal compounds, Si-based compounds, or metal silicide compounds,
A photomask wherein the material of the upper layer film is selected from a Cr-based metal compound, a Si-based compound, or a metal silicide compound and is different from the lower layer film.
A process of preparing a photomask blank having a lower layer film on a transparent substrate, a middle film on the lower layer film, and an upper layer film on the middle film;
Positive type on the upper layer A process of forming a resist film;
an exposure process of exposing the resist film to form a first region, a second region, and a third region all having different exposure amounts;
a first resist removal process for selectively removing the first region;
a first patterning process of selectively etching the upper layer with respect to the middle layer;
a second patterning process of selectively etching the middle layer with respect to the lower layer layer;
a second resist removal process to selectively remove the second region;
a third patterning process of forming a pattern composed of the lower layer film and a pattern composed of a laminated film of the lower layer film, the middle film, and the upper layer film;
and a third resist removal process for removing the third region in this order,
In the exposure process,
The third area is an unexposed area,
The first area is exposed to a higher exposure amount than the second area,
The cross-sectional shape of the resist film of the edge portion of the third region after the second resist removal process is the boundary portion where the second region and the third region contact each other after the first resist removal process. A method of manufacturing a photomask, characterized in that the shape is steeper than the cross-sectional shape of the resist film.
According to claim 11,
The upper layer is a light blocking film,
The middle film is an etching stopper film,
The third patterning process is,
A method of manufacturing a photomask, comprising the step of etching the middle layer after etching the lower layer and the upper layer.
According to claim 11,
The upper layer film is an antireflection film,
The middle film is a light blocking film,
The second patterning process is
After a process of selectively etching the middle layer with respect to the lower layer layer,
Further comprising a process of selectively etching the lower layer with respect to the middle layer,
The third patterning process is,
After selectively etching the upper layer with respect to the middle layer,
A method of manufacturing a photomask, comprising the step of selectively etching the middle layer with respect to the upper layer and the lower layer.
The method according to any one of claims 11 to 13,
A method of manufacturing a photomask, wherein the upper layer film and the lower layer film are composed of the same material.
The method according to any one of claims 11 to 13,
A method of manufacturing a photomask, wherein the upper layer film and the lower layer film are composed of a Cr-based metal compound, a Si-based compound, or a metal silicide compound.
The method according to any one of claims 11 to 13,
A photomask manufacturing method, characterized in that the transmittance of the laminated film is adjusted by adjusting the material or film thickness of the upper layer film.
The method according to any one of claims 11 to 13,
A method of manufacturing a photomask, wherein the underlayer film is a semi-transmissive film with a transmittance of 10% to 70% and a phase shift amount of 0 degrees to 20 degrees.
The method according to any one of claims 11 to 13,
A method of manufacturing a photomask, wherein the underlayer film is a phase shift film with a transmittance of 3% to 15% and a phase shift amount of 160 degrees to 200 degrees.
In the photomask manufactured according to claim 11,
A pattern composed of the lower layer film on a transparent substrate, and a pattern composed of a stacked film having the middle film and the upper layer film in this order on the lower layer film,
The material of the lower layer film is selected from Cr-based metal compounds, Si-based compounds, or metal silicide compounds,
A photomask characterized in that the material of the upper layer film is selected from a Cr-based metal compound, a Si-based compound, or a metal silicide compound and is the same as the material of the lower layer film.
According to claim 19,
A photomask characterized in that the lower layer film is a semi-transmissive film with a transmittance of 10% to 70% and a phase shift amount of 0 degrees to 20 degrees.
According to claim 19,
A photomask characterized in that the lower layer film is a phase shift film with a transmittance of 3% to 15% and a phase shift amount of 160 degrees to 200 degrees.