JPH07253649A - Mask for exposure and projection aligning method - Google Patents

Abstract

PURPOSE:To provide a mask for exposure capable of improving the resolving power for isolated patterns and depth of focus to an equal level as the periodic patterns in a Levenson type phase shift method and improving the accuracy of pattern exposure. CONSTITUTION:This mask for exposure formed with desired mask patterns on a light transmissive substrate 101 has a first film 104 which is so formed as to have opening patterns on this light transmissive substrate 101 and has light shieldability to both of a first exposing wavelength lambda1 and a second exposing wavelength lambda2 and a second film 103 which is formed selectively in the opening patterns of the first film 104, has light transmissivity at the first exposing wavelength lambda1, imparts a phase difference of 180 deg. to the transmitted light and has light shieldability at the second exposing wavelength lambda2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection exposure technique used for lithography in a semiconductor device manufacturing process,
In particular, the present invention relates to an exposure mask using a phase shift effect and a projection exposure method using the same.

[0002]

2. Description of the Related Art In recent years, as semiconductor technology has progressed, semiconductor devices have been becoming faster and more highly integrated. With this trend, the need for finer patterns has become even higher, and the pattern dimensions have become finer and higher. Precision is required.
For the purpose of satisfying this requirement, short-wavelength light such as far-ultraviolet light has been used as an exposure light source. However, in the process using the 248 nm oscillation line of the KrF excimer laser, which is about to be used as the exposure light source in the future, in the exposure light,
Although a chemically amplified resist is being developed, a dedicated resist is still in the research stage.

Therefore, recently, attempts have been made to reduce the pattern size without changing the exposure light source. A phase shift method is one of the methods. This method is intended to improve the pattern accuracy by partially providing a phase inversion layer in the light transmitting portion and causing negative interference of light in adjacent patterns.

Among the phase shift methods, the Levenson-type phase shift method (Japanese Patent Publication No.
No. 50811). In this method, a mask having a light-shielding pattern is provided, and phase shifters are alternately provided in the light transmitting portions. By adjusting this phase shifter so as to invert 180 ° with respect to the light transmitted through the portion where the phase shifter is not arranged, negative interference of light is generated between the patterns to improve the resolution performance.

However, the Levenson-type phase shift method has a large improvement in the resolution performance and the depth of focus with respect to the periodic pattern, but on the other hand, there is a limitation in the pattern arrangement such that the isolated pattern has no effect.

On the other hand, a method of producing a phase shift effect by setting the phase difference between the region adjacent to the light-shielding film and the main opening adjacent to the light-shielding film to 180 ° (edge light-shielding method) or the semitransparent film having the phase-shifting effect. By applying the method (halftone method), it is possible to improve the resolution and the depth of focus for an isolated pattern. However, with these methods, it was difficult to obtain a dramatic improvement effect like the Lebeson type phase shift method.

[0007]

As described above, although the resolution and depth of focus for an isolated pattern can be improved to some extent by the edge shading method or the halftone method, it is equivalent to the periodic pattern in the Levenson type phase shift method. It has been difficult to improve the resolution and depth of focus for isolated patterns.

The present invention has been made in consideration of the above circumstances, and an object thereof is to improve the resolving power and the depth of focus for an isolated pattern as well as the periodic pattern in the Levenson-type phase shift method. An object of the present invention is to provide an exposure mask and a projection exposure method capable of improving the pattern exposure accuracy.

[0009]

The essence of the present invention is to improve the resolution performance and the depth of focus by combining periodic pattern exposure and isolated pattern exposure for isolated patterns and to improve the Levenson for periodic patterns. By applying the type phase shift method, the resolution and the depth of focus can be improved.

That is, the present invention (Claim 1) is an exposure mask in which a desired mask pattern is formed on a transparent substrate, and is formed so as to have an opening pattern on the transparent substrate. A first film having a light-shielding property at both the exposure wavelength and the second exposure wavelength, and a transmitted light having a light-transmitting property at the first exposure wavelength, which is selectively formed in the opening pattern of the first film. And a second film having a light shielding property at the second exposure wavelength.

Here, the following are preferred embodiments of the present invention. (1) The light having the first exposure wavelength that passes through the second film has a phase difference that is an integral multiple of 180 ° with respect to the light that passes through the transparent substrate. (2) As a method of manufacturing an exposure mask, a transparent substrate is translucent to the first exposure wavelength, gives a desired phase difference to the transmitted light, and has a light shielding property to the second exposure wavelength. Forming a second film adjusted so that the first film has a light-shielding property at both the first exposure wavelength and the second exposure wavelength, and the first film Partially removing the first and second portions exposed from the removed region of the first film.
Partially removing the film of the above. (3) As a method of manufacturing an exposure mask, a light-transmitting substrate has a light-transmitting property with respect to a first exposure wavelength, gives a desired phase difference to transmitted light, and has a light-shielding property with respect to a second exposure wavelength. Forming a second film adjusted so as to have a light-shielding property at both the first exposure wavelength and the second exposure wavelength, and a step of partially removing the second film. 1. forming a pattern made of the film of 1. (4) As a method of manufacturing an exposure mask, a step of partially etching a transparent substrate, and at least the etched region is transparent to the first exposure wavelength and has a desired phase difference with respect to the transmitted light. And forming a second film adjusted to have a light-shielding property with respect to the second exposure wavelength;
Partially removing the film of the first exposure wavelength and the second exposure wavelength
There is provided an exposure mask manufacturing method including a step of forming a pattern made of a first film having a light shielding property at any of the exposure wavelengths. (5) The pattern made of the first film has periodicity, and the desired pattern is expressed by the sum of the pattern made of the first film and the pattern made of the second film.

According to the present invention (claim 2), in an exposure mask in which a desired mask pattern is formed on a transparent substrate, the exposure mask is formed to have an opening pattern on the transparent substrate. A first film having a light-shielding property at both the exposure wavelength and the second exposure wavelength, and an opening pattern of the first film, which is selectively formed and has a light-transmitting property at the first exposure wavelength. Second having a light shielding property at an exposure wavelength of 2
Film and the opening pattern of the first film are selectively formed,
And a third film having a light-transmitting property at a first exposure wavelength and giving a desired phase difference to the transmitted light.

The preferred embodiments of the present invention are as follows. (1) The light having the first exposure wavelength that passes through the third film has a phase difference that is an integral multiple of 180 ° with respect to the light that passes through the transparent substrate. (2) The light of the first exposure wavelength transmitted through the second film is an odd multiple of 180 ° (or an even multiple) of the light transmitted through the transparent substrate.
The light having the first exposure wavelength that has a phase difference of ## EQU3 ## and has a phase difference that is an integral multiple (or an odd multiple) of 180 ° with respect to the light that transmits the transparent substrate. (3) The phase of light transmitted through the second film and the third film at the first exposure wavelength is different by an odd multiple of 180 °, and the aperture of the translucent substrate is different from that of the translucent substrate. The phase of light transmitted through the second film to the third film adjacent to is adjusted to be different by an odd multiple of 180 °. (4) The first exposure wavelength and the second
The step of forming a first film having a light-shielding property at any of the exposure wavelengths, the step of removing at least a part of the first film to form a pattern made of the first film, and the first exposure wavelength A step of forming a pattern composed of a second film having a light-transmitting property and adjusted so as to have a phase difference of an odd multiple of 180 ° with respect to the light transmitted through the light-transmitting substrate; (3) forming a pattern made of a third film having a light-transmitting property and having a phase difference adjusted to an even multiple of 180 ° with respect to light transmitted through the light-transmitting substrate. (5) The pattern made of the first film has periodicity, and the desired pattern is expressed by the sum of the pattern made of the first film and the pattern made of the second film.

The present invention (claim 3) is a projection exposure method for transferring a pattern formed on a mask onto a substrate to be exposed, wherein the first exposure wavelength and the second exposure wavelength are provided on the transparent substrate. In any of the above, the first film having a light-shielding property is formed to have an opening pattern, has a light-transmitting property at the first exposure wavelength, gives a desired phase difference to the transmitted light, and has a second exposure. An exposure mask in which a second film having a light blocking property at a wavelength is selectively formed in the opening pattern of the first film is used, and the exposure mask is irradiated at the same position with respect to the optical axis as the first exposure wavelength. Do it twice at the second exposure wavelength,
Each of the mask images obtained by the first and second exposure wavelengths is projected onto the same position on the substrate to be exposed.

The preferred embodiments of the present invention are as follows. (1) Irradiation to the exposure mask should be performed once by selecting the first exposure wavelength and the second exposure wavelength of the projection exposure apparatus at the same time. (2) Irradiation on the exposure mask is performed twice by selecting the exposure wavelength of the projection exposure apparatus separately for the first exposure wavelength and the second exposure wavelength. (3) A photosensitive material having photosensitivity to both the first exposure wavelength and the second exposure wavelength is formed on the substrate to be exposed. (4) A first photosensitive resin film, which is exposed to the second exposure wavelength and hardly exposed to the first exposure wavelength, is formed on the substrate to be exposed, and is exposed to the first exposure wavelength on the first photosensitive resin film. 2. The photosensitive resin film 2 is formed.

[0016]

The basic structure of the exposure mask of the present invention will be described below. A pattern made of a first film having a light blocking property at both the first exposure wavelength and the second exposure wavelength is formed on a transparent substrate. It is desirable to arrange this pattern periodically. In the exposure mask of the present invention, a periodical pattern is basically used, and only the pattern made of the first film is transferred by performing the exposure with the first exposure wavelength. Here, a pattern composed of a second film that is transparent to the first exposure wavelength and adjusted to have a phase difference of an odd multiple of 180 ° with respect to the light transmitted through the transparent substrate, By alternately forming the openings formed between the patterns of the first film,
A phase shift effect is produced with respect to the exposure wavelength of, and a high resolution and a wide depth of focus can be obtained.

Here, the second film has two functions of selectivity for the first and second exposure wavelengths and formation of a phase difference with respect to the first exposure wavelength. These functions are the second and third. It may be distributed to the film.

It should be noted that what is obtained by this exposure is an optical image of a periodic pattern, not an optical image of a desired isolated pattern. Therefore, for the purpose of increasing the integrated light intensity in the portion corresponding to the isolated pattern in the periodic pattern, that portion is exposed with the second exposure wavelength. At this time, the second film and the third film having a light shielding property at the second exposure wavelength (only when the third film has a light shielding property at the second exposure wavelength) also become a dark part, and these patterns and The entire area in which the pattern made of the first film is arranged is formed as a dark area pattern.

By performing exposure using two types of exposure wavelengths in this manner, the integrated light intensity of the isolated pattern portion can be increased as compared with other patterns. On the other hand, in the substrate to be exposed, the relative magnitude of the light intensity is further formed as an isolated pattern by using a photosensitive resin material, that is, a material that develops when irradiated with a specific exposure amount or more. can do. Further, when a material that develops in a region irradiated with a specific exposure amount or less is used, it can be formed as an isolated leaving pattern.

[0020]

EXAMPLES The present invention will be described in detail below with reference to examples. (Embodiment 1) FIG. 1 is a diagram showing an exposure mask and a projection exposure method according to a first embodiment of the present invention. The present embodiment relates to an exposure mask that performs periodic pattern transfer for KrF exposure (λ1 = 248 nm) and performs isolated pattern transfer for ArF exposure (λ2 = 193 nm).

In the exposure mask, a pattern of a light shielding film (first film) 104 made of Cr + CrO is formed on the lower surface of the transparent substrate 101, and a SiN film (first film) is formed on a part of the lower surface of the transparent substrate 101. Second film) 103 is embedded.
The SiN film 103 forms a phase difference of 180 degrees with respect to the light having the wavelength λ1 that passes through the substrate 101 and blocks the light having the wavelength λ2.

Using such an exposure mask, a substrate coated with a resist having photosensitivity at both exposure wavelengths of KrF light and ArF light was exposed. First, by irradiating with KrF light (wavelength λ1) as an exposure light source, as shown in FIG. 1A, a region corresponding to the opening pattern of the light shielding film 104 became a dark part and an optical image was formed.

At this time, the SiN film 103 has a phase of 18
Since there is a shift of 0 degrees, the phase difference of light passing through each pattern of the mask becomes 180 degrees depending on the presence or absence of the SiN film 103. Therefore, if the SiN film 103 is formed in the opening pattern adjacent to the opening pattern without the SiN film 103, the SiN film 103
The doping profile for the opening pattern without the film 103 becomes steep. Reference numeral 110 is transmitted light that passes through the transparent portion of the substrate, and 111 is transmitted light that passes through the SiN film 103 and is 180 degrees out of phase.

Then, ArF light (wavelength λ2) is used as an exposure light source for irradiation without changing the relative position of the substrate and the mask, and as shown in FIG.
The area where 3 or 104 was present became a dark area, and an optical image was formed. In other words, when irradiated with light of wavelength λ2, SiN
The passing light 120 is obtained only from the opening pattern without the film 103.

By developing this and removing only the area irradiated with a certain amount of light or more, the resist can be removed in the area irradiated with light in both exposures, and a fine pattern can be formed. It was That is, the wavelengths λ1 and λ2
1 (c) by performing the exposure twice with the light of FIG.
As shown in FIG. 3, only the image of the opening pattern without the SiN film 103 is well formed on the substrate to be exposed, and the isolated pattern can be formed with high resolution.

In the present embodiment, it was possible to accurately form an isolated space 0.2 μm pattern by using a 0.4 μm periodic pattern of 104: line: space = 1: 1.

FIG. 2 is a cross-sectional view showing the manufacturing process of the exposure mask of this embodiment. First, as shown in FIG. 2A, a photosensitive resin film is formed on a translucent substrate 101 made of SiO ₂ , and light exposure and development are performed to form a photosensitive resin pattern 102. Subsequently, as shown in FIG. 2B, the transparent substrate 101 is partially etched using the photosensitive resin pattern 102 as a mask, and the resist is further removed. In the case of substrate etching, 248 n of SiN is used.
The refractive index at m was set to be approximately 248/2 (n-1.5).

Next, as shown in FIG. 2 (c), a SiN film 103 is formed on the surface of the translucent substrate 101 etched by the CVD method. The film formation amount at this time is 150 n
m. Subsequently, as shown in FIG. 2D, the surface on which the SiN film 103 was formed was mechanically ground until the transparent substrate surface was exposed. After that, as shown in FIG. 2E, a chrome 70 nm and a chrome oxide 30 nm were sequentially formed by a sputtering method on at least a part of the surface of the substrate on which the SiN film 103 was formed to form a light shielding film 104.

Next, as shown in FIG. 2F, a photosensitive resin film was formed on this substrate, and light exposure and development were performed to form a photosensitive resin pattern 105. Subsequently, as shown in FIG. 2G, the light-shielding film 104 was partially etched using the photosensitive resin pattern 105 as a mask, and the resist was removed to form a desired exposure mask.

In this embodiment, the surface of the substrate is flattened by mechanical polishing. However, after the SiN film 103 is formed by the CVD method, the surface is covered with a resin film and further heat-treated to flatten the surface. It is also possible to perform processing while maintaining planarity by performing non-selective etching (etching under the same etching rate for substances exposed on the surface during etching). In this method, Ar
Although the SiN film is used as the material having the light shielding property for the F light and the light transmitting property for the KrF light, any material may be used as long as it has the same property for these exposure wavelengths. . In addition, by adjusting the composition of the substances that form the film,
The degree of the light shielding property for F light and the light transmitting property for ArF light may be changed.

Although the present embodiment has described the method of manufacturing a mask having wavelength dependence with respect to ArF light and KrF light, the present invention is not limited to this, and one of the combinations of other exposure wavelengths is also applicable. This can be applied by using a substance having a light-transmitting property for light and a light-shielding property for the other light instead of the SiN film. Further, as a modification of this embodiment, the light shielding film 104 as the first film and the SiN film 103 as the second film may be configured as shown in FIGS. (Embodiment 2) FIG. 3 is a diagram showing an exposure mask and a projection exposure method according to a second embodiment of the present invention. 2 in the figure
01, 203, 204, 210, 211 and 220 are 101, 103, 104, 110, 111 and 120 of FIG.
Is equivalent to.

The basic structure of this embodiment is the same as that of the first embodiment, but in this embodiment, the second film 203 has a wavelength λ.
1 has some light absorption. As a means of providing light absorption, for example, the proportion of silicon in the SiN film 203 may be increased.

With such a structure, the intensity of light passing through the second film 203 in KrF exposure can be made lower than the intensity of light passing through the transparent portion of the substrate 201.
As a result, a halftone phase shift effect can be provided. Therefore, the resolution and depth of focus for an isolated pattern can be improved more than in the first embodiment. (Embodiment 3) FIG. 4 is a diagram showing an exposure mask and a projection exposure method according to a third embodiment of the present invention. In the present embodiment, periodic pattern phase shift transfer is performed for i-line exposure (λ1 = 365 nm), and KrF exposure (λ2 = 248n) is performed.
m) to an exposure mask for performing isolated pattern transfer.

The exposure mask is formed by embedding a SiN film (second film) 303 in a part of the lower surface of the transparent substrate 301,
A pattern of a light shielding film (first film) 304 is formed on the lower surface,
Further, a SiO ₂ film (third film) 307 is formed so as to cover a part of the opening pattern of the light shielding film 304.
The second film 303 transmits light of wavelength λ1 and blocks light of wavelength λ2. The third film 307 is for providing a phase difference of 180 degrees with respect to the light of wavelength λ1.

Using such an exposure mask, a substrate coated with a resist having a photosensitivity at both exposure wavelengths of i-ray light (wavelength λ1) and KrF light (wavelength λ2) of a mercury lamp is exposed. went. First, when i-ray light from a mercury lamp was used as an exposure light source, irradiation was performed.
As shown in (a), a region corresponding to the pattern of the light shielding film 304 became a dark part and an optical image was formed.

At this time, the phase is 1 in the SiO ₂ film 307.
Since it is shifted by 80 degrees, the phase difference of light passing through each pattern of the mask becomes 180 degrees depending on the presence or absence of the SiO ₂ film 307. Therefore, by forming the SiO ₂ film 307 in the opening pattern adjacent to free the opening patterns SiO ₂ film 307, doped profile for free opening patterns SiO ₂ film 307 is steep. In addition, 310 is transmitted light that passes through the transparent portion of the substrate, and 311 is a SiO ₂ film 307.
Transmitted light having a phase shift of 180 degrees and 312 is SiN
It is the transmitted light that passes through the film 303 and has the same phase as 310.

Then, when irradiation was performed using KrF light as an exposure light source without changing the relative position of the substrate and the mask, as shown in FIG.
The area in which there was was a dark area, and an optical image was formed. That is, when the light having the wavelength λ2 is irradiated, the passing light 320 is obtained only from the opening pattern without the SiN film 303.

By developing this and removing only the area irradiated with a certain amount of light or more, the resist can be removed in the area irradiated with light in both exposures, and a fine pattern can be formed. It was That is, the wavelengths λ1 and λ2
4 (c) by performing the exposure twice with the light of FIG.
As shown in FIG. 3, only the image of the opening pattern without the SiN film 303 is well formed on the substrate to be exposed, and the isolated pattern can be formed with high resolution.

In the present embodiment, it was possible to accurately form an isolated space 0.3 μm pattern by using a periodic pattern of 304: line: space = 1: 1 with a pitch of 0.6 μm.

FIG. 5 is a cross-sectional view showing the manufacturing process of the exposure mask of this embodiment. First, as shown in FIG. 5A, the transparent substrate 301 made of SiO ₂ is partially etched in the same manner as in the first embodiment, and S
The iN film 303 was embedded, and a pattern of the light shielding film 304 was further formed.

Here, the etching amount of the substrate 301 is adjusted by adjusting the composition to be formed on the portion etched in the later step.
For iN, the exposure wavelength λ1 used as a light-transmitting film and the refractive index n1 of SiN whose composition was adjusted at that time were set to a depth of at least d = λ1 (n1-1.47) or more.
Then, the film thickness of the composition-adjusted SiN is d = 202 nm.
(N1 = 2.8 in this example) and the polishing was completed when it became almost equal.

Next, as shown in FIG. 5B, a photosensitive resin film was formed on this substrate, and light exposure and development were performed to form a photosensitive resin pattern 306. Then, as shown in FIG. 5C, using the photosensitive resin pattern 306 as a mask, the openings of the pattern and SiO ₂ and SiN are formed.
A SiO ₂ film 307 was selectively grown in the liquid phase from the surface. The film formation amount at this time was 424 nm in consideration of the refractive index of 1.43 of the selectively grown SiO ₂ film 307.

Finally, as shown in FIG. 5D, the photosensitive resin pattern 306 was removed to form a pattern composed of the SiO ₂ film 307. In this example, the surface of the substrate was flattened by mechanical polishing.
After the iN film 303 is formed by the CVD method, the surface is covered with a resin film and further subjected to heat treatment for flattening, and non-selective etching (etching is performed under the same etching conditions for the substances exposed on the surface during the etching process). By doing so, it is possible to perform processing while maintaining flatness.

In this embodiment, the thickness of the SiN film 303 is d.
= Λ1 / (n1-1.47), but this thickness is d =
λ1 / (2 (n1-1.47)), and the SiO ₂ film pattern may be arranged as shown in FIG. 5 (e).

Further, in this embodiment, a SiN film having a composition adjusted as a material having a light-shielding property with respect to KrF and having a light-transmitting property with respect to the i-line of mercury was used, but the same is applied to these exposure wavelengths. Any substance may be used as long as it has a property. Further, in this embodiment, the SiO ₂ pattern is formed by the liquid phase growth method, but the SiO ₂ film may be partially removed by forming the film by a method such as CVD and using the photosensitive resin pattern as a mask. Further, in this embodiment, the SiO ₂ film is used for the purpose of adjusting the phase of the transmitted light with respect to the i-line of mercury, but a material having a light-transmitting property with respect to the i-line of mercury may be used instead. Absent.

Further, as shown in FIG. 3 (e), the SiO ₂ film is adjusted so as to give a phase difference of substantially 0 ° to the light transmitted through the substrate with respect to the exposure light, and the film thickness of the SiN film is adjusted. It is also possible to improve the resolution performance of the isolated pattern and the depth of focus by adjusting so as to give a phase difference of 180 ° to the light transmitted through the substrate.

Although the present embodiment has described the method of manufacturing the mask having wavelength dependence with respect to the i-line of mercury and KrF, the present invention is not limited to this, and one of the two light beams can be used in combination with other exposure wavelengths. A substance having a light-transmitting property with respect to λ1 and a light-shielding property with respect to the other light is used instead of the SiN film, and at least a film having a light-transmitting property at λ1 is S.
It can be applied by using it instead of the iO ₂ film (phase adjusting film).

As a modification of this embodiment, the light-shielding film 304 as the first film, the light-shielding film 304, and the second film are used.
SiN film 303 as the second film and S as the second film
The iO ₂ film 307 may be configured as shown in FIGS. (Embodiment 4) FIG. 6 is a diagram showing an exposure mask and a projection exposure method according to a fourth embodiment of the present invention. 4 in the figure
01, 403, 404, 407, 410, 411, 41
2, 420 are 301, 303, 304, 30 of FIG.
It corresponds to 7,310,311,312,320.

The basic structure of this embodiment is the same as that of the third embodiment, but in this embodiment, the second film 403 has a wavelength λ.
1 has some light absorption. As a means for providing light absorption, for example, the proportion of silicon in the SiN film 403 may be increased.

With such a configuration, the intensity of the light passing through the second film 403 in the i-line exposure can be made lower than the intensity of the light passing through the transparent portion of the substrate 401, whereby the halftone is performed. A phase shift effect can be provided. Therefore, the resolution and depth of focus for the isolated pattern can be improved more than in the third embodiment. (Embodiment 5) FIG. 7 is a diagram showing an exposure mask and a projection exposure method according to a fifth embodiment of the present invention. In the present embodiment, periodic pattern phase shift transfer is performed for KrF exposure (λ1 = 248 nm), and ArF exposure (λ2 = 193n) is performed.
m) to an exposure mask for performing isolated pattern transfer.

In the exposure mask, the pattern of the light shielding film 504 is formed on the lower surface of the transparent substrate 501, and the light shielding film 50 is further formed.
No. 4 SiO ₂ film 52 so as to cover part of the opening pattern.
1, 522 are formed. SiO ₂ film has wavelength λ
It transmits the light of No. 1 and gives a desired phase difference and blocks the light of wavelength λ2.

Using such an exposure mask, exposure was performed on a substrate coated with a resist having photosensitivity at both exposure wavelengths of ArF light and KrF light. First, when irradiation was performed using KrF light (λ1) as an exposure light source, as shown in FIG.
The area corresponding to the pattern of No. 2 became a dark area and an optical image was formed.

At this time, the phase is 1 in the SiO ₂ film 521.
The phase shifts by 80 degrees and the SiO ₂ film 522 shifts by 360 degrees.
Therefore, by forming the SiO ₂ film 521 in the opening pattern adjacent to free the opening patterns SiO ₂ film, SiO
_The doping profile for the opening pattern without the _two films 521 and 522 becomes steep. It should be noted that 510 is transmitted light that passes through the transparent portion of the substrate, 511 is transmitted light that is transmitted through the SiO ₂ film 521 and is 180 degrees out of phase, and 512 is SiO _2.
It is the transmitted light that passes through the film 522 and has the same phase as 510.

Next, when the exposure light source was irradiated with ArF light (λ2) without changing the relative position of the substrate and the mask, as shown in FIG.
The area where each of 1, 522 was present became a dark part, and an optical image was formed. That is, when the light of wavelength λ2 is irradiated, S
The transmitted light 520 is obtained only from the opening pattern without the iO ₂ films 521 and 522.

By developing this and removing only the region irradiated with a certain amount of light or more, the resist can be removed in the region irradiated with light in both exposures, and a fine pattern can be formed. It was That is, the wavelengths λ1 and λ2
7 (c) by performing the exposure twice with the light of FIG.
As shown in FIG. 5, only the image of the opening pattern without the SiO ₂ films 521 and 522 is well formed on the substrate to be exposed, and the isolated pattern can be formed with high resolution.

In the present embodiment, it was possible to accurately form an isolated space 0.2 μm pattern by using a periodic pattern of 504 lines: space = 1: 1 with a 0.4 μm pitch. In addition, the resolution of an isolated pattern is also obtained in the method of increasing the ratio of silicon in the SiO ₂ film to the film having the matched phase difference as in this embodiment so as to have a function of slightly absorbing KrF light. It is possible to improve performance and depth of focus.

FIG. 8 is a cross-sectional view showing the manufacturing process of the exposure mask of this embodiment. First, as shown in FIG. 8A, a light-shielding film 504 was formed by forming a film of chromium 70 nm and chromium oxide 30 nm on at least a part of a transparent substrate 501 made of SiO ₂ by a sputtering method. continue,
As shown in FIG. 8B, a photosensitive resin film is formed on the substrate, and a photosensitive resin pattern 505 is formed by performing light exposure and development, and the light shielding film 504 is partially etched using this as a mask. To form an opening pattern, and
As shown in (c), the resist was removed and a desired exposure mask was prepared.

Next, as shown in FIG. 8 (d), a photosensitive resin film is formed and exposed to light and developed to form a photosensitive resin pattern 508, which is selectively exposed from the SiO ₂ surface in the liquid phase. Then, a SiO ₂ film 521 was grown. The film formation amount at this time was 276 nm in consideration of the refractive index of 1.45 of the selectively grown SiO ₂ film 521. Also, this SiO
_{The 2} film 521 has an intensity transmittance of almost 100% for KrF (248 nm), but has an ArF (193 nm) of 276 n.
When it is used in a thickness of m, the intensity transmittance is 1% or less.

Next, after removing the photosensitive resin pattern 508, as shown in FIG. 8E, a photosensitive resin film is formed, and light exposure and development are performed to form a photosensitive resin pattern 509. . Then, a SiO ₂ film 522 was selectively grown in the liquid phase from the SiO ₂ surface. The film formation amount at this time was 552 nm in consideration of the refractive index of 1.45 of the selectively grown SiO ₂ film 522. And FIG.
As shown in (f), the photosensitive resin pattern 509 was removed to form a phase shift pattern.

In this embodiment, a SiO ₂ film having a composition adjusted as a material having a light shielding property against ArF light and a light transmitting property with KrF light is used. Any substance may be used as long as it has a property.

Further, although the SiO ₂ pattern was formed by the liquid phase epitaxy method in this embodiment, even if the film is formed by a method such as CVD and the SiO ₂ film is partially removed using the photosensitive resin pattern as a mask. I do not care. Furthermore, an SiO ₂ film was used for the purpose of adjusting the phase of transmitted light with respect to KrF light.
Any material that has a property of transmitting rF and a property of blocking ArF light may be used instead.

Although the present embodiment has described the method of manufacturing a mask having wavelength dependence with respect to ArF light and KrF, the present invention is not limited to this, and one light can be used for other combinations of exposure wavelengths. This can be applied by using a substance having a light-transmitting property and a light-shielding property with respect to the other light for the phase adjustment film.

In the present embodiment, 504 is a SiN film having a composition adjusted to have a light-shielding property for ArF light and a light-transmitting property for KrF light, but the present invention is not limited to this.
Any exposure wavelength may be combined as long as is a combination of exposure wavelengths having a light-shielding property. Also, the material is not limited to this.

[0064]

As described above, the exposure mask of the present invention is intended to improve resolution performance and depth of focus by combining periodic pattern exposure and isolated pattern exposure for isolated patterns. Further, by applying the Levenson-type phase shift method to these patterns in the periodic pattern exposure, it is possible to further improve the resolution performance and the depth of focus.

[Brief description of drawings]

FIG. 1 is a diagram showing an exposure mask and a projection exposure method according to a first embodiment.

FIG. 2 is a cross-sectional view showing the manufacturing process of the exposure mask in the first embodiment.

FIG. 3 is a diagram showing an exposure mask and a projection exposure method according to the second embodiment.

FIG. 4 is a diagram showing an exposure mask and a projection exposure method according to a third embodiment.

FIG. 5 is a cross-sectional view showing the manufacturing process of the exposure mask in the third embodiment.

FIG. 6 is a diagram showing an exposure mask and a projection exposure method according to a fourth embodiment.

FIG. 7 is a diagram showing an exposure mask and a projection exposure method according to the fifth embodiment.

FIG. 8 is a cross-sectional view showing the manufacturing process of the exposure mask in the fifth embodiment.

FIG. 9 is a sectional view showing a modification of the first embodiment.

FIG. 10 is a sectional view showing a modification of the third embodiment.

[Explanation of symbols]

101, 201, 301, 401, 501 ... Translucent substrate 102, 105, 306, 505, 508, 509 ... Photosensitive resin pattern 103, 203, 303, 403 ... SiN film (second film) 104, 204, 304, 404, 504 ... Shading film (first film) 307, 407 ... SiO ₂ film (third film) 521, 522 ... SiO ₂ film 110, 210, 310, 410, 510 ... λ1 transmitted light (substrate part) Same phase) 111, 211, 311, 411, 511 ... λ1 transmitted light (anti-phase with substrate part) 120, 220, 320, 420, 520 ... λ2 transmitted light (in-phase with substrate part) 312, 412, 512 ... λ1 transmitted light (same phase as substrate)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location H01L 21/027

Claims (3)

[Claims] 1. An exposure mask in which a desired mask pattern is formed on a transparent substrate, the first exposure wavelength and the second exposure wavelength being formed so as to have an opening pattern on the transparent substrate. In either case, the first film having a light-shielding property and the opening pattern of the first film are selectively formed, and have a light-transmitting property at the first exposure wavelength and have a desired phase difference with respect to the transmitted light. An exposure mask comprising a second film which is provided and has a light-shielding property at a second exposure wavelength. 2. An exposure mask in which a desired mask pattern is formed on a transparent substrate, the first exposure wavelength and the second exposure wavelength being formed so as to have an opening pattern on the transparent substrate. In any of the above, the first film having a light shielding property and the opening pattern of the first film are selectively formed, and have a light transmitting property at the first exposure wavelength and a light shielding property at the second exposure wavelength. And a third film selectively formed in the opening pattern of the first film and having a light-transmitting property at the first exposure wavelength and giving a desired phase difference to the transmitted light. An exposure mask comprising: 3. A light-shielding film having a light-shielding property at both the first exposure wavelength and the second exposure wavelength is formed on a transparent substrate so as to have a desired opening pattern, and at the first exposure wavelength. An exposure mask is used in which an auxiliary film having a light-transmitting property and giving a desired phase difference to the transmitted light and having a light-shielding property at a second exposure wavelength is selectively formed in an opening pattern of the first film. , The exposure mask is irradiated twice at the first exposure wavelength and the second exposure wavelength at the same position with respect to the optical axis, and each mask image obtained by the first and second exposure wavelengths is exposed on the substrate to be exposed. A projection exposure method characterized in that projection is performed at the same position.