JPH03211554A - Production of phase shift mask - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] A method for manufacturing a mask used in an exposure step in the manufacturing process of a semiconductor device, particularly used in an interference exposure method that improves resolution by utilizing the coherence of light. Regarding a method for manufacturing a phase shift mask, it is possible to prevent a phase shift film pattern from being shifted by one position when forming a phase shift film, and to form a device pattern and a phase shift group using the same film, Furthermore, the present invention aims to provide a method for manufacturing a phase shift mask that requires only one electron beam lithography process, and is configured using any of the following means.

The first method is to place a non-transparent film such as aluminum, chrome, tin, zinc, tantalum, or silicon on a transparent substrate, and then oxidize the non-transparent film to form a transparent film. The oxide film is formed to a thickness suitable for inverting the phase of the irradiated light, a resist layer is formed, and this resist layer is patterned and removed from the phase shift film forming area to make it opaque. the non-transparent film corresponding to the phase shift film forming region from which the resist layer has been removed is oxidized to convert into a transparent oxide film to form a phase shift film; Then, the resist layer is removed, and the non-transparent film is selectively removed in an area excluding the area surrounded by the transparent oxide film using, for example, an electrolytic etching method. The device pattern is formed by leaving the light-opaque film in a region surrounded by the phase shift film to form a device pattern.

The second method is to apply a non-transparent film made of aluminum, chrome, tin, zinc, tantalum, or silicon on a transparent substrate, and to form a non-transparent film by oxidizing the non-transparent film. The oxide film is formed to a thickness suitable for inverting the phase of the irradiated light, a resist layer is formed, and this resist layer and the above-mentioned non-transparent film are patterned to form the above-mentioned oxide film. The non-transparent film and the resist layer are removed from the area excluding the device pattern forming area to expose the non-transparent film, and the peripheral area of the non-transparent film is oxidized to make the non-transparent film transparent. It consists of a step of converting into a photosensitive oxide film to form a phase shift film. The third method is to form a non-transparent film such as aluminum, chrome, tin, zinc, tantalum, or silicon on a transparent substrate, and to form a non-transparent film by oxidizing the non-transparent film. The oxide film is formed to a thickness suitable for inverting the phase of the irradiated light, and this non-transparent film is patterned and removed from areas other than the device pattern forming area, and the resist layer is removed. forming the resist layer, patterning the resist layer, and removing it from the phase shift M formation region to expose the light-opaque film, corresponding to the phase shift film formation head from which the resist layer is removed. The method includes a step of oxidizing the non-transparent film to convert it into a transparent oxide film to form a phase shift (Ill). A fourth method is to form a metal film on a light-transmitting substrate, pattern the metal film to remove the device pattern formation region from <sI region, and remove aluminum, chrome, tin, zinc, tantalum, or Forming a non-transparent film such as silicon to a thickness such that the thickness of a transparent oxide film formed by oxidizing the non-transparent film is suitable for inverting the phase of irradiated light, This non-transparent film is patterned to remain in the phase shift film forming area, and the non-transparent film remaining in the phase shift film forming area is oxidized to convert it into a transparent oxide film. The method includes a step of forming a phase shift waist.

[Industrial application field]

The present invention relates to an improvement in a method for manufacturing a mask used in an exposure step in a semiconductor device manufacturing process. especially,
The present invention relates to an improvement in a method for manufacturing a phase shift mask used in interference exposure method that improves resolution by utilizing the coherence of light.

[Prior Art] As seen in semiconductor memory, the degree of integration of LSI devices has increased fourfold in three to four years.
High integration is progressing rapidly. In order to improve the degree of integration, it is necessary to reduce the dimensions of devices, and it is important to develop a method for forming fine patterns that makes it possible to reduce device dimensions. #! It has become.

Conventionally, a metal film such as chrome is formed on a transparent substrate such as quartz, this metal film is patterned, and the transparent substrate with a device pattern formed on it is used as a mask or reticle. There is. When using this mask or reticle to transfer a pattern onto a wafer, ultraviolet or deep ultraviolet rays are often used. Equal to or about 2 wavelengths
As the size has been doubled, it has become extremely difficult to transfer patterns onto wafers with sufficient resolution. In order to solve this difficult problem, measures have been taken to increase the aperture ratio (NA) of the exposure equipment and shorten the exposure wavelength, but these measures are approaching their technical limits. be.

Therefore, as shown in FIGS. 5(a) and 5(b) (FIG. 5(a) is a cross-sectional view taken along the line A-A in FIG. 5(b)), A phase shift film 5 that inverts the phase of the exposure light is formed surrounding the formed device pattern 4 made of a light shielding film, and a phase shift film 5 that inverts the phase of the exposure light suppresses the amount of Fresnel diffraction of the exposed ultraviolet or far ultraviolet light and improves the resolution. A shift mask was developed.

As shown in FIG. 6(a), the conventional method for manufacturing a phase shift mask is to form, for example, a chrome film 7 as a light-shielding film on a quartz substrate l, and to pattern this, as shown in FIG. 6(b).
) as shown in FIG. is the wavelength of the light, and n is the refractive index of the SOG film.
), 5OGI1 is formed on the device pattern 4 made of the chrome film 7 and in the area surrounding the device pattern 4.
In this method, the SOG film 9 formed in the region surrounding the device pattern 4 is used as a phase shift film.

[Invention tries to solve! [Subject]

By the way, the conventional method of manufacturing a phase shift mask having a phase shift film has the following problems.

(b) Since an insulator is often used as the material for the phase shift film, electron beam hT imaging performed in the step of patterning this insulator film to form the phase shift M A charge-up phenomenon occurs, and the electron beam iii! The position of the pattern of the phase shift a shifted from the normal position.

(b) After forming a device pattern made of a metal film such as chrome, a film such as an insulator for forming the phase shift H must be separately formed.

(c) Expensive electron beam lithography must be used twice in the device pattern patterning process and the phase shift film patterning process.

The purpose of the present invention is to eliminate these drawbacks,
It has the following three purposes.

The first object is to provide a method for manufacturing a phase shift mask that is improved so that the positional shift of the pattern of phase shift) 1] 1] does not occur when forming a phase shift film.

A second object is to provide a method for manufacturing a phase shift mask that is improved so that a device pattern and a phase shift film can be formed using the same film.

A third object is to provide a method for manufacturing a phase shift mask that is improved so that the phase shift mask can be manufactured by performing an electron beam lithography process only once.

[Means to solve the problem]

The first of the above three objectives is achieved by any of the following first, second, third and fourth means, and the second of the above three objectives is: The third objective of the above three objectives can be achieved by any of the first and second means below. Ru.

The first means is to place aluminum on a transparent substrate (1),
The thickness of the transparent oxide film formed by oxidizing the non-transparent film (2) such as chromium, tin, zinc, tantalum, or silicon is determined by the irradiation light. The resist layer (3) is formed to a thickness suitable for phase inversion.
) is formed, and this resist layer (3) is patterned and removed from the phase shift film formation region to form a non-transparent film l(2).
The non-transparent film (2) corresponding to the phase shift film formation sI region from which the resist layer (3) has been removed is oxidized to become a transparent oxide film (21). converting to form a phase shift M (5) and removing said resist layer (3), for example using an electrolytic etching method, excluding the area surrounded by said transparent oxide film (21); selectively removing said non-transparent film (2) in the region and changing said phase shift l.
! The above-mentioned non-transparent film 1(2) is placed in the area surrounded by 1(5).
This is a method for manufacturing a phase shift mask, which includes a step of forming a device pattern (4) by leaving a remaining portion of the phase shift mask.

The second means is to place aluminum on a transparent substrate (1).
The thickness of the transparent oxide film formed by oxidizing the non-transparent film (2) such as chromium, tin, zinc, tantalum, or silicon is determined by the irradiation light. The resist layer (3) is formed to a thickness suitable for phase inversion.
), and this resist layer (3) and the above-mentioned non-transparent H
(2) and patterned to form the above-mentioned non-transparent film (2).
and the resist layer (3) are removed from the area excluding the device pattern forming area to expose the non-transparent film (2), and the peripheral area of the non-transparent film (2) is removed. It is oxidized and converted into a transparent oxide film (21) to form a phase shift II (5).
This is a method for manufacturing a phase shift mask, which includes a step of forming a phase shift mask.

The third means is to place aluminum on a transparent substrate (1).
Opaque to chrome, tin, zinc, tantalum, or silicone 1! (2) is formed to a thickness such that the thickness of the transparent oxide film formed by oxidizing the non-transparent film (2) is suitable for inverting the phase of the irradiated light. The non-transparent film (2) is patterned and removed from the region excluding the device pattern formation region, a resist layer (6) is formed, and this resist layer (6) is patterned to remove it from the phase shift film formation region. The non-transparent film (2) is removed to expose the non-transparent film (2), and the non-transparent film (2) corresponds to the removed phase shift a formation region of the resist layer (6).
This method of manufacturing a phase shift mask is characterized by comprising a step of oxidizing and converting the phase shift film (21) into a transparent oxide film (21) to form a phase shift film (5).

The fourth method is to form a metal film (7) on a transparent substrate (1), pattern this metal film (7) to remove the device pattern formation area (remove from the N castle,
The thickness of the transparent oxide film formed by oxidizing the non-transparent film (2) such as chromium, tin, zinc, tantalum, or silicon is determined by the irradiation light. The non-light-transmitting film (2) is formed to a thickness suitable for inverting the phase, and is patterned to remain in the phase shift film formation region, and the non-transparent film (2) remains in the phase shift film formation region. Oxidize the non-transparent film (2) to make it transparent oxidation 1]9 (21)
This is a method for manufacturing a phase shift mask, which includes a step of forming a phase shift film (5).

[Effect]

The first, second, third, and fourth means use a transparent oxide film, which is formed by oxidizing a partial head region of a non-transparent film on which a device pattern is formed, as a phase shift film. Therefore, when forming a phase shift film, it is sufficient to perform electron beam writing on the resist layer formed on the conductive non-transparent film before oxidation.
At times, charge-up of electrons is eliminated, and misalignment of the pattern of the phase shift film is prevented.

Furthermore, in the first, second, and third means,
Since a part of the light-opaque film formed for device pattern formation is oxidized and converted to phase shift III, there is no need to form a flill for phase shift Ill formation separately from that for device pattern formation. Furthermore, in the first and second means, only one expensive electron beam lithography process is required, so there is a great economic benefit.

〔Example〕

Hereinafter, methods for manufacturing phase shift masks according to four embodiments of the present invention will be described with reference to the drawings.

At t'' t, an aluminum film 2 is formed on the quartz &@1 with a thickness of about 1.5 to 5.0 mm as shown in FIG. 1(a). At this time, the thickness of the aluminum film 2 is The transmittance of ultraviolet rays or deep ultraviolet rays used for Film thickness α
is selected so that it satisfies equation (1).

α=λ/2(n-1) (1) where n is the refractive index of alumina formed by anodizing and converting aluminum, and λ is the wavelength of exposure light.

If the exposure light wavelength λ is 0.41 m and the refractive index n of alumina formed by anodizing and converting aluminum is 1.55 (in the case of λ-0.4n), then aluminum is the anode. The film thickness α of alumina formed by oxidation and conversion is 0.31n from formula (1), and the film thickness α of alumina formed by anodization and conversion is 0.3n.
The thickness of the aluminum film to become 1n is 0.2n. The exposure light transmittance of a 0.2n thick aluminum film is l/
It is 1000 or less, and has sufficient light-shielding properties.

Referring to FIG. 1(b), a resist layer 3 is formed on the aluminum film 2, and using an electron beam lithography method, the resist layer 3 is removed from the phase shift film forming region.

See Figure 1(c) Ammonium borate saturated solution in ethylene glycol, 2
% in an electrolytic solution such as an aqueous sulfuric acid solution, and conducts anodic oxidation by applying current to the aluminum film 2 as an anode, thereby oxidizing the exposed aluminum film 2 and converting it into an alumina film 21.

The resist layer 3 shown in FIG. 1(d) is removed and immersed in an electrolytic solution such as a mixture of borofluoric acid and water, a mixture of phosphoric acid, sulfuric acid, and chromic anhydride, and then surrounded by the alumina 821. Electrolytic etching is carried out by applying current to the aluminum H2 in the area excluding the open castles formed as an anode, and removing the aluminum film 2 in the area excluding the device pattern forming area surrounded by the alumina film 21, forming a device pattern 4 made of the aluminum film 2. A phase shift mask having a phase shift film 5 made of alumina 1]'121 formed around it is formed.

Referring to FIG. 2(a), aluminum H2 is formed on a quartz substrate l to the same thickness as in Example 1]1].

Refer to FIG. 2(b) A resist N3 was formed on the aluminum H2, and the resist layer 3 was patterned using an electron beam lithography method to remove the resist layer 3 from the area excluding the device pattern forming area. The aluminum film 2 is etched using the resist layer 3, and the aluminum H2 is removed from the region excluding the device pattern forming region.

Referring to FIG. 2(c) With the resist layer 3 remaining, the aluminum film 2 is anodized using the same method as in the first example to convert the peripheral region of the aluminum H2 into an alumina film 21.

Referring to FIG. 2(d), the resist layer 3 is removed and the device pattern 4 made of the aluminum film 2 is surrounded by alumina! A phase shift mask in which a phase shift 81I5 of 121 is formed is formed.

Referring to FIG. 3(a), an aluminum film 2 is formed on the quartz aEMI to the same thickness as in the first example.

Refer to FIG. 3(b) A resist layer 3 is formed on the aluminum film 1.142, the resist layer 3 is patterned using electron beam lithography, and the aluminum film 2 is etched using the patterned resist layer 3. Then, the aluminum film 2 is removed from the region excluding the device pattern forming region.

Referring to FIG. 3(c), the resist layer 3 is removed and a resist layer 6 is formed again.
The resist layer 6 is patterned using an electron beam lithography method, and the aluminum remaining in the device pattern forming area! It remains in the region excluding the phase shift film forming region on l12.

The aluminum film 2 is anodized using the same method as in the first example to convert the exposed area of the aluminum film 2 into an alumina film 21.

Referring to FIG. 3(d), the resist layer 6 is removed and the device pattern 4 made of aluminum M2 is surrounded by alumina l! Phase shift consisting of 21! Form a $5 phase shift mask.

5, a light-shielding film of, for example, chrome 1]7 is formed to a thickness of 500 on a quartz substrate 1 having a thickness of about 1.5 to 5.0 mm (see FIG. 4(a)).

4(b), form a resist layer 3 on the chrome 1], pattern the resist layer 3 using electron beam lithography, and etch chrome 1II7 using the patterned resist layer 3, Chrome 1 from the area excluding the device pattern forming area]! Remove 7.

Refer to FIG. 4(c) After removing the resist layer 3, aluminum 1] 12 is formed to the same thickness as in the first example, a resist layer 8 is formed thereon, and an electron beam lithography method is used to form the resist layer 8. The resist layer 8 is patterned, the patterned resist layer 8 is used to etch the aluminum film 2, and the chrome 1]? The aluminum film 2 is removed from the region excluding the top and the phase shift film formation region at the periphery of the chrome film 7.

FIG. 4(d) The reference resist layer 8 is removed, and the aluminum film 2 is anodized using the same method as in the first example to convert it into an alumina film 21, and a device pattern 4 made of a chrome film 7 is formed. A phase shift mask having a phase shift film 5 made of alumina 1]1]21 formed thereon is formed.

Note that the phase change can also be achieved by using a chrome film, tin film, zinc film, tantalum film, or silicon film in place of the aluminum 1t12 formed in the first, second, third, and fourth embodiments. Shift masks can be manufactured.

(Effects of the Invention) As explained above, in the method for manufacturing a phase shift mask according to the present invention, a partial region of a non-transparent film formed for device pattern formation is oxidized to become a transparent oxide film. This translucent oxide film is used as a phase shift film, so in the electron beam lithography process of the phase shift mask manufacturing process, electrons are transferred to the resist layer formed on the conductive non-transparent ridge. All that is required is beam lithography, which eliminates charge-up of electrons and prevents phase shift). Furthermore, since the device pattern and the phase shift (M) can be formed on the same film, and only one electron beam lithography process is required, there is great economic benefit.

[Brief explanation of drawings]

1 to 4 are process diagrams illustrating a method for manufacturing a phase shift mask according to an embodiment of the present invention. FIG. 5 is an explanatory diagram of the structure of the phase shift mask. FIG. 6 is a process diagram illustrating a method of manufacturing a phase shift mask according to the prior art. 1... Transparent substrate (quartz substrate), 2... Non-transparent film (aluminum W4) 21... Transparent oxide film (alumina m>, 3... Resist layer, ・Device pattern , ・Phase shift film, ・Resist layer, ・Metal (chrome film) ・Resist layer, ・Transparent film (SOGIll)

Claims (1)

[Scope of Claims] [1] A non-transparent film (2) is placed on a transparent substrate (1), a translucent oxide film formed by oxidizing the non-transparent film (2). A resist layer (3) is formed, and the resist layer (3) is patterned to have a thickness suitable for inverting the phase of the irradiated light. removing the resist layer to expose the non-transparent film (2), and oxidizing the non-transparent film (2) corresponding to the phase shift film forming region from which the resist layer (3) has been removed; to form a phase shift film (5) by converting it into a transparent oxide film (21), and removing the resist layer (3) and converting it into a transparent oxide film (21).
1) The non-light-transparent film (2) in the area excluding the area surrounded by
selectively removing the non-transparent film (2) to leave the non-transparent film (2) in a region surrounded by the phase shift film (5) to form a device pattern (4). How to make a shift mask. [2] After removing the resist layer (3), electrolytic etching is used to remove the non-transparent film (2) in the area excluding the area surrounded by the transparent oxide film (21). The method for manufacturing a phase shift mask according to claim 1, wherein the phase shift mask is selectively removed. [3] A non-transparent film (2) is placed on a transparent substrate (1), and the thickness of the transparent oxide film formed by oxidizing the non-transparent film (2) is determined by the irradiation light. A resist layer (3) is formed, and the resist layer (3) and the light-opaque film (2) are patterned to form a resist layer (3) having a thickness suitable for reversing the phase of the light-transmitting film. The light-transmitting film (2) and the resist layer (3) are removed from the area excluding the device pattern forming area to form the non-light-transmitting film (2).
and oxidizing the peripheral region of the non-transparent film (2) to convert it into a transparent oxide film (21) to form a phase shift film (5). A method of manufacturing a phase shift mask. [4] A non-transparent film (2) is placed on the transparent substrate (1), and the thickness of the transparent oxide film formed by oxidizing the non-transparent film (2) is determined by the irradiation light. The non-transparent film (2) is formed to a thickness suitable for reversing the phase of the resist layer (6), and the non-transparent film (2) is patterned and removed from the region excluding the device pattern forming region.
The resist layer (6) is patterned and removed from the phase shift film formation region to form the non-transparent film (2).
The non-transparent film (2) corresponding to the removed phase shift film forming region of the resist layer (6) is oxidized to convert into a transparent oxide film (21), and the phase shift film is exposed. A method for manufacturing a phase shift mask, comprising the step of forming a shift film (5). [5] Forming a metal film (7) on the transparent substrate (1), patterning the metal film (7) and removing it from the area excluding the device pattern formation area, and forming the non-transparent film (2). is formed to a thickness such that the thickness of the transparent oxide film formed by oxidizing the non-transparent film (2) is suitable for inverting the phase of the irradiated light, and patterning the transparent film (2) to remain in the phase shift film formation region, and the non-transparent film (2) remaining in the phase shift film formation region;
A method for manufacturing a phase shift mask, comprising the step of oxidizing 2) to convert it into a transparent oxide film (21) to form a phase shift film (5). [6] The material of the non-transparent film (2) is aluminum,
Claims [1], [2], [3], [ characterized in that the material is chromium, tin, zinc, tantalum, or silicon.
4] or the method for manufacturing a phase shift mask according to [5].