JPH1184624A - Blank for halftone type phase shift mask, halftone type phase shift mask, and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high pattern forming accuracy, satisfy an optical constant as a phase shift mask, control a reflectance at exposure light and a transmittance at an inspection wavelength, and improve conductivity. It is an object of the present invention to provide a blank for a halftone type phase shift mask and a halftone type phase shift mask which have a transparent film and a translucent film which are combined. SOLUTION: A transparent film 2 and a translucent film 3 made of a zirconium silicide compound thin film (a zirconium oxide silicide film and a zirconium carbonitride silicide film) are formed on a transparent substrate 1 by reactive sputtering using a zirconium silicide target. Thus, a blank 100 for a halftone type phase shift mask is manufactured. further,
The halftone type phase shift mask blank 100 is patterned by subjecting the halftone type phase shift mask blank 100 to a halftone type phase shift mask 2 comprising a transparent film pattern 2a and a semitransparent film pattern 3a.
00 is produced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photomask for exposing and transferring when forming a pattern in a photolithography step in a semiconductor manufacturing process, and a photomask blank for manufacturing the photomask. The present invention relates to a tone-type phase shift photomask or a blank for producing the same.

[0002]

2. Description of the Related Art In a conventional photomask, when a fine pattern is projected and exposed, light that has passed through a light transmitting portion of the mask is diffracted and interferes with each other to enhance the light intensity at a pattern boundary portion. Since the resist is exposed to light, there has been a problem that the pattern transferred on the wafer is not separated and resolved. This phenomenon is more likely to occur for finer patterns closer to the exposure wavelength. In principle, it was impossible to resolve a fine pattern having a wavelength equal to or less than the wavelength of light using a conventional photomask and a conventional exposure optical system.

Therefore, a phase shift mask using a phase shift technique has been developed, in which the phase difference between projection lights transmitted through adjacent patterns is set to 180 degrees to improve the resolution of a fine pattern. In other words, by providing a phase shift portion on one side of the adjacent opening, when transmitted light is diffracted and interferes with each other, the light intensity at the boundary is weakened due to the phase inversion, so that the transfer pattern is separated. Resolve. Since this relationship is established before and after the focal point, even if the focal point is slightly shifted, the resolution is improved as compared with the conventional method, and the focus latitude is improved.

The phase shift method as described above is based on IBM's Le.
proposed by Venson et al.
No. 744, and in principle, Japanese Patent Publication No. 62-50811. When the pattern is formed by a light-shielding layer, a phase shift portion is provided on one side of the opening adjacent to the light-shielding pattern and the phase is inverted, but the light-shielding layer does not have complete light-shielding properties, and the translucent light-shielding layer Even when the phase is inverted, a similar resolution improving effect is obtained, and in this case, it is particularly effective for improving the resolution of an isolated pattern.

FIGS. 5 (a) to 5 (c) are views for explaining the resolution when projection exposure is performed on a wafer using a halftone type phase shift mask. Of the exposure light perpendicularly incident on the mask surface, the exposure light I and III attenuate when passing through the translucent light-shielding pattern 32, but about 8% of the light is transmitted. Exposure light II is 100% transparent substrate 31
Since the transmitted light passes through, the amplitude distribution of the exposure light on the wafer is as shown in FIG. Here, from the relationship that the square of the amplitude of light is proportional to the light intensity, the intensity distribution of the exposure light projected on the wafer surface is as shown in FIG. The light intensity at the boundary with is zero. As a result, the contrast of the pattern edge is improved, and the resolution of the pattern is improved. further,
The same effect is maintained before and after the focus, so that even if there is a slight defocus, the resolution is increased, and the effect of improving the focus latitude is obtained.

A phase shift mask that provides such an effect is generally called a halftone type.

[0007]

In a halftone type phase shift mask (including a mask blank), the original optical characteristics of the phase shift mask include the phase inversion amount at the exposure wavelength: 180 ± 3 degrees and the exposure wavelength. Transmittance: 3-1
In addition to 5% (in-plane variation: ± 0.5%), it is necessary to simultaneously satisfy the characteristics of a reflectance of 25% or less at the exposure wavelength and a transmittance of 30% or less at the inspection wavelength. The reason for this is that if the reflectivity of the photomask at the exposure wavelength is high, multiple reflections occur between the translucent film and the wafer during photolithography, resulting in reduced pattern accuracy.

In the inspection and dimension measurement of the phase shift mask, light in the visible light range such as e-line (546 nm) of an ultra-high pressure mercury lamp or Ar + ion laser light (488 nm) is mainly used. Is 30%
If the ratio exceeds the above range, there arises a problem that inspection and dimension measurement become difficult due to a decrease in contrast between the transmissive portion and the translucent portion.

In electron beam lithography for exposing an electron beam resist on a semitransparent film, if the conductivity of the semitransparent film is low, electrons are charged up and a pattern cannot be formed accurately. Alternatively, there is also a problem that dust is easily adsorbed during a mask manufacturing process or during use due to electrostatic charging.

In order to avoid the above problems, there is a phase shift mask in which two or more films are superposed to suppress the reflectance with respect to exposure light or to impart conductivity to the film surface. For example, a material using molybdenum silicide, a material using chromium, and the like can be given. However, as the exposure wavelength becomes shorter, each of these films has problems in controllability and reproducibility of the film in the sputtering process, and many problems such as high transmittance in an inspection wavelength region have been pointed out. I have.

In order to solve the above-mentioned drawbacks of the conventional halftone type phase shift mask, the present invention has a high pattern formation precision, satisfies the optical constants as a phase shift mask, and has a high reflectance with exposure light. It is an object of the present invention to provide a blank for a halftone type phase shift mask and a halftone type phase shift mask which have a transparent film and a semitransparent film which can control the transmittance at the wavelength and the inspection wavelength and also have conductivity.

[0012]

In order to solve the above-mentioned problems in the present invention, a first aspect of the present invention relates to a halftone type phase shift mask having a transparent film and a translucent film on a light transmitting substrate. A blank for a halftone phase shift mask, wherein the transparent film and the translucent film are made of a zirconium silicide compound thin film.

According to a second aspect of the present invention, the zirconium silicide compound thin film is made of a zirconium oxide silicide film and a zirconium oxide silicide film. It is.

According to a third aspect of the present invention, the transparent film on the translucent substrate is made of a zirconium oxide carbide silicide film, and the translucent film is made of a zirconium oxide silicide film. This is a blank for a halftone type phase shift mask as described. .

According to a fourth aspect of the present invention, the transparent film on the light-transmitting substrate is made of a zirconium oxide silicide film, and the translucent film is made of a zirconium oxide silicide film. This is a blank for a halftone type phase shift mask as described.

According to a fifth aspect of the present invention, there is provided a halftone type phase shift mask comprising a transparent film and a translucent film provided on a translucent substrate, and the transparent film and the translucent film are patterned. A halftone type phase shift mask, wherein the translucent film is made of a zirconium silicide compound thin film.

According to a sixth aspect of the present invention, there is provided the halftone phase shift mask according to the fifth aspect, wherein the zirconium silicide compound thin film comprises a zirconium oxide silicide film and a zirconium oxide carbide silicide film. .

According to a seventh aspect of the present invention, there is provided a halftone type phase shift mask in which a transparent film and a translucent film are provided on a translucent substrate, and the transparent film and the translucent film are patterned. 7. The halftone phase shift mask according to claim 5, wherein the halftone type phase shift mask is made of a zirconium oxide silicide film, and the translucent film is made of a zirconium oxide silicide film.

According to another aspect of the present invention, in a halftone type phase shift mask in which a transparent film and a translucent film are provided on a translucent substrate, and the transparent film and the translucent film are patterned. 7. The half-tone phase shift mask according to claim 5, wherein the half-transparent film is formed of a zirconium oxide silicide film, and the translucent film is formed of a zirconium oxide carbide silicide film.

In a ninth aspect of the present invention, a zirconium oxide silicide film is formed on a translucent substrate in a mixed gas atmosphere of argon and carbon dioxide by using a zirconium silicide target. The method for producing a halftone phase shift mask blank according to any one of claims 1 to 4, wherein a zirconium oxide silicide film is formed.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The halftone type phase shift mask of the present invention comprises a transparent film having an opening pattern and a translucent film on a transparent glass substrate, and the transparent film and the translucent film are zirconium silicide compound thin films (oxidized Optical conditions that are satisfactory as a phase shift mask (transmittance of an exposure wavelength transmitting through a multilayer film: 3% to 15%) are composed of a zirconium silicide film and a zirconium carbide oxide silicide film.
(In-plane variation: ± 0.5%), phase difference with light passing through the aperture pattern: 180 ± 3 degrees), the reflectance at the exposure wavelength is 25% or less, and the transmittance at the inspection wavelength is 30% or less, and furthermore, imparting a certain degree of conductivity to the translucent film to prevent charge-up during electron beam drawing, improve the pattern formation accuracy, and totally improve the pattern resolution during exposure transfer. It is something that can be done.

The zirconium oxide silicide film and the zirconium carbide oxide silicide film constituting the transparent film and the translucent film are formed by reactive sputtering using a zirconium silicide target in a reactive gas atmosphere.

First, a highly transparent zirconium oxide silicide film is formed on a transparent quartz glass substrate, and then a translucent zirconium oxide silicide film is formed to form a halftone type phase shift mask blank. obtain. In addition, a highly transparent zirconium oxide silicide film is formed on a transparent quartz glass substrate, and then a translucent zirconium oxide silicide film is formed to obtain another halftone type phase shift mask blank. . Here, the zirconium oxide silicide film and the zirconium carbide oxide silicide film are each formed so that the refractive index and the extinction coefficient are set in advance by the mask configuration so that the film thickness satisfies the optical conditions as a phase shift mask. Film.

An electron beam resist is applied to the blank for the halftone type phase shift mask, and a halftone type phase shift mask is obtained through a series of patterning processes such as electron beam drawing, development, baking, etching and resist peeling. . Here, since the transparent film and the translucent film are made of a single metal compound of zirconium silicide, a mask pattern can be formed accurately and easily.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a blank for a phase shift mask and a phase shift mask according to the present invention will be described more specifically with reference to the drawings. 1A to 1C show a configuration and a manufacturing process of a blank for a phase shift mask and a phase shift mask. <Embodiment 1> This is an embodiment of a blank for a KrF-compatible two-layer halftone phase shift mask and a phase shift mask. A zirconium oxide silicide film is used for the transparent film, and a zirconium oxide silicide film is used for the translucent film.

First, using an RF sputtering apparatus, argon (Ar) gas and carbon dioxide (C
O ₂ ) gas was introduced, and a transparent film 2 made of a zirconium oxide carbide film was formed on a transparent substrate 1 made of a transparent quartz glass by reactive sputtering using a zirconium silicide target.

Next, argon (Ar) gas and oxygen (O ₂ ) gas are introduced into the chamber, and reactive sputtering using a zirconium silicide target is performed.
A translucent film 3 made of a zirconium oxide silicide film was formed on the transparent film 2 to produce a halftone type phase shift mask blank 100 (see FIG. 1A). At this time, the combined film thickness of the transparent film 2 and the translucent film 3 was 1145 °.

Film forming conditions Film forming conditions for transparent film 2 (zirconium oxide silicide film) Power: 200 W Pressure: 0.45 Pa Ar / CO ₂ (%): 87/13 Translucent film 3 (zirconium oxide silicide film) ) Film forming conditions Power: 200 W Pressure: 0.43 Pa Ar / O ₂ (%): 90/10

FIG. 2 shows the spectral transmittance characteristics and the spectral reflectance characteristics of the halftone type phase shift mask blank 100 manufactured under the above film forming conditions. As is clear from FIG. 2, the spectral transmittance at 248 nm, which is the wavelength of the KrF excimer laser, is 5.1%, and the inspection wavelength is 488 nm.
Is 24.5%, and the transmittance at an inspection wavelength of 365 nm is 15.0%, and a sufficient contrast at the time of inspection can be obtained. The wavelength of the exposure light is 248n.
The reflectance at m was 25.9%, which was a value that was satisfactory from the viewpoint of reducing the effect of multiple reflection during exposure.

Since the transparent film has almost no absorption, blanks having different transmittances at the exposure wavelength can be easily produced by changing the thickness of the translucent film. At this time, the phase difference may be adjusted by the thickness of the transparent film.

After cleaning the halftone type phase shift mask blank 100, an electron beam resist is applied by a spinner to form an electron beam resist layer, and a predetermined pattern is drawn by an electron beam and developed to form a resist pattern having an opening 5. 4
Was formed (see FIG. 1B). Here, the sheet resistance of the two-layer zirconium silicide compound film formed under the above-described film forming conditions was 6.7 kΩ / □, and charge-up at the time of electron beam drawing hardly caused a problem.

Next, the semi-transparent film 3 and the transparent film 2 are patterned by dry etching using the resist pattern 4 as a mask.
A two-layer halftone phase shift mask 200 composed of the transparent pattern 2a and the translucent film pattern 3a was obtained (FIG. 1).
(C)).

<Embodiment 2> Here is another embodiment of a blank for a KrF-compatible two-layer halftone type phase shift mask and a phase shift mask. A zirconium oxide silicide film is used for the transparent film, and a zirconium oxide silicide film is used for the translucent film.

First, an argon (Ar) gas and an oxygen (O ₂ ) gas are introduced into a chamber using an RF sputtering apparatus, and a transparent quartz glass is formed by reactive sputtering using a zirconium silicide target. A transparent film 2 made of a zirconium oxide silicide film was formed on a conductive substrate 1.

Next, an argon (Ar) gas and a carbon dioxide (CO ₂ ) gas are introduced into the chamber, and a translucent film made of a zirconium oxycarbide silicide film is formed on the transparent film 2 by reactive sputtering using a zirconium silicide target. The film 3 was formed, and a blank 100 for a halftone phase shift mask was produced (see FIG. 1A). At this time, the combined film thickness of the transparent film 2 and the translucent film 3 was 1240 °.

Film forming conditions Film forming conditions for transparent film 2 (zirconium oxide silicide film) Power: 200 W Pressure: 0.45 Pa Ar / O ₂ (%): 87/13 Semi-transparent film 3 (zirconium oxide silicide film) ) Film forming conditions Power: 200 W Pressure: 0.43 Pa Ar / CO ₂ (%): 23/2

FIG. 3 shows the spectral transmittance characteristics and the spectral reflectance characteristics of the halftone type phase shift mask blank 100 manufactured under the above film forming conditions. As is clear from FIG. 3, the spectral transmittance at 248 nm, which is the wavelength of the KrF excimer laser, is 5.3%, and the inspection wavelength is 488 nm.
The transmittance at m is 29.0%, and the transmittance at an inspection wavelength of 365 nm is 16.2%, and a sufficient contrast at the time of inspection can be obtained. The wavelength of the exposure light is 248.
The reflectance in nm was 23.7%, which was a value that was satisfactory from the viewpoint of reducing the influence of multiple reflection during exposure.

Further, since the transparent film has almost no absorption, blanks having different transmittances at the exposure wavelength can be easily produced by changing the thickness of the translucent film. At this time, the phase difference may be adjusted according to the thickness of the transparent film.

After cleaning the halftone type phase shift mask blank 100, an electron beam resist is applied by a spinner to form an electron beam resist layer, and a predetermined pattern is drawn by an electron beam and developed to form a resist pattern having an opening 5. 4
Was formed (see FIG. 1B). Here, the sheet resistance of the two-layer zirconium silicide compound film formed under the above film formation conditions was 11.6 kΩ / □, and charge-up at the time of electron beam drawing hardly caused a problem.

Next, the semi-transparent film 3 and the transparent film 2 are patterned by dry etching using the resist pattern 4 as a mask.
A halftone type phase shift mask 200 composed of the transparent pattern 2a and the translucent film pattern 3a was obtained (FIG. 1C).
reference).

<Embodiment 3> This is another embodiment of a blank for a two-layer halftone type phase shift mask and a phase shift mask corresponding to ArF. A zirconium oxide silicide film was used for the transparent film, and a zirconium oxide silicide film was used for the translucent film.

First, an argon (Ar) gas and an oxygen (O ₂ ) gas are introduced into a chamber by using an RF sputtering apparatus, and a light transmission made of transparent quartz glass is performed by reactive sputtering using a zirconium silicide target. A transparent film 2 made of a zirconium oxide silicide film was formed on a conductive substrate 1.

Next, an argon (Ar) gas and a carbon dioxide (CO ₂ ) gas are introduced into the chamber, and a half of a zirconium oxide carbide film is formed on the transparent film 2 by reactive sputtering using a zirconium silicide target. The transparent film 3 was formed, and a blank 100 for a halftone phase shift mask was manufactured (see FIG. 1A). At this time, the total film thickness of the transparent film 2 and the translucent film 3 was 905 °.

Film forming conditions Film forming conditions for transparent film 2 (zirconium oxide silicide film) Power: 200 W Pressure: 0.45 Pa Ar / O ₂ (%): 87/13 Semi-transparent film (zirconium oxide silicide film) Power: 200 W Pressure: 0.43 Pa Ar / CO ₂ (%): 23/2

FIG. 4 shows the spectral transmittance characteristics and the spectral reflectance characteristics of the blank 100 for a halftone phase shift mask manufactured under the above film forming conditions. The spectral transmittance at 193 nm, which is the wavelength of the ArF excimer laser, is 5.0%.
The transmittance at the inspection wavelength of 365 nm is 25.8%, and a sufficient contrast at the time of inspection can be obtained. The reflectivity of the exposure light at a wavelength of 193 nm was 25.4%, which was a value that was satisfactory from the viewpoint of reducing the influence of multiple reflection during exposure.

Since the extinction coefficient of the transparent film is small, blanks having different transmittances at the exposure wavelength can be easily produced by changing the thickness of the translucent film. At this time, the phase difference may be adjusted by the thickness of the transparent film.

After cleaning the halftone type phase shift mask blank 100, an electron beam resist is applied by a spinner to form an electron beam resist layer, and a predetermined pattern is drawn by electron beam and developed to form a resist pattern having an opening 5. 4
Was formed (see FIG. 1B). Here, the sheet resistance of the two-layer zirconium silicide compound film formed under the above-described film forming conditions was 15.2 kΩ / □, and charge-up at the time of electron beam drawing hardly caused a problem.

Next, after the translucent film 3 and the transparent film 2 are dry-etched and patterned by using the resist pattern 4 as a mask, the resist pattern 4 is subjected to a film removing treatment to form the transparent film pattern 2a and the translucent film pattern 3a. A two-layer halftone phase shift mask 200 made of
(C)).

[0049]

According to the blank and the phase shift mask for a halftone type phase shift mask, by using a zirconium silicide compound thin film for the transparent film and the translucent film, not only the optical conditions as the phase shift mask but also the exposure light The reflectance and the transmittance at the inspection wavelength can be easily controlled. Further, since it is a single metal compound, it has high pattern formation accuracy and excellent pattern shape reproducibility. Further, since the film itself has an appropriate conductivity, charge-up at the time of electronic drawing does not have to be a problem. That is, (1) The multilayer film composed of the transparent film and the translucent film of the present invention has a transmittance of 5 to 15% at an exposure wavelength, a high-pressure mercury lamp i-line (365 nm) and an Ar ion laser beam (488 n) used for inspection.
m) and the like, the transmittance is 30% or less at the inspection wavelength.
For this reason, a sufficient contrast at the time of inspection can be obtained, and no special transmittance adjusting film or the like is required. (2) Further, since the reflectance with respect to the exposure wavelength is 25% or less and is not affected by multiple reflection during exposure, an antireflection layer is not required. (3) Since it has sufficient conductivity (sheet resistance of 50 MΩ / □ or less), it is possible to prevent charge-up during electron beam drawing. (4) Since the multilayer film is hard, a defect due to damage or abrasion in a process for manufacturing a phase shift mask or an inspection process can be suppressed. (5) Sufficient resistance to hot concentrated sulfuric acid in the washing step.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view showing a configuration of a blank for a halftone type phase shift mask of the present invention. (B) ~
(C) is sectional drawing which shows the structure and manufacturing process of the halftone type phase shift mask of this invention.

FIG. 2 is a first embodiment of a blank for a halftone phase shift mask and a halftone phase shift mask according to the present invention;
FIG. 3 is an explanatory diagram showing a spectral transmittance characteristic and a spectral reflectance characteristic of FIG.

FIG. 3 is a second embodiment of a blank for a halftone phase shift mask and a halftone phase shift mask according to the present invention.
FIG. 3 is an explanatory diagram showing a spectral transmittance characteristic and a spectral reflectance characteristic of FIG.

FIG. 4 is a third embodiment of a blank for a halftone phase shift mask and a halftone phase shift mask according to the present invention.
FIG. 3 is an explanatory diagram showing a spectral transmittance characteristic and a spectral reflectance characteristic of FIG.

FIG. 5A is an explanatory diagram illustrating a case where projection exposure is performed using a halftone type phase shift mask. FIG. 4B is an explanatory diagram illustrating an amplitude distribution of exposure light on a wafer. (C) is an explanatory diagram showing the intensity distribution of exposure light on the wafer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Translucent board 2 ... Transparent film 2a ... Transparent film pattern 3 ... Translucent film 3a ... Translucent film pattern 4 ... Resist pattern 5 ... Opening 31 ... Translucent substrate 32 ... … Semi-transparent light shielding pattern 100 …… Blank for halftone type phase shift mask 200 …… Halftone type phase shift mask

Claims (9)

[Claims] A halftone type phase shift mask blank having a transparent film and a translucent film on a light transmitting substrate,
A halftone type phase shift mask blank, wherein the transparent film and the translucent film are made of a zirconium silicide compound thin film. 2. The halftone phase shift mask blank according to claim 1, wherein said zirconium silicide compound thin film comprises a zirconium oxide silicide film and a zirconium oxide silicide film. 3. The halftone phase according to claim 1, wherein the transparent film on the translucent substrate is made of a zirconium oxide silicide film, and the translucent film is made of a zirconium oxide silicide film. Blank for shift mask. 4. The halftone phase according to claim 1, wherein the transparent film on the light-transmitting substrate is made of a zirconium oxide silicide film, and the translucent film is made of a zirconium oxide silicide film. Blank for shift mask. 5. A transparent film and a translucent film are provided on a translucent substrate,
A halftone phase shift mask obtained by patterning the transparent film and the translucent film, wherein the transparent film and the translucent film are made of a zirconium silicide compound thin film. 6. The halftone phase shift mask according to claim 5, wherein said zirconium silicide compound thin film is composed of a zirconium oxide silicide film and a zirconium oxide silicide film. 7. A transparent film and a translucent film are provided on a translucent substrate,
In a halftone type phase shift mask obtained by patterning the transparent film and the translucent film, the transparent film is made of a zirconium oxide silicide film, and the translucent film is made of a zirconium oxide silicide film. 7. The halftone phase shift mask according to 5 or 6. 8. A transparent film and a translucent film are provided on a translucent substrate,
In a halftone type phase shift mask obtained by patterning the transparent film and the translucent film, the transparent film is made of a zirconium oxide silicide film, and the translucent film is made of a zirconium oxide silicide film. 7. The halftone phase shift mask according to 5 or 6. 9. Using a zirconium silicide target, a zirconium oxide silicide film is formed on a translucent substrate in a mixed gas atmosphere of argon and oxygen, and a zirconium oxide silicide film is formed in a mixed gas atmosphere of argon and carbon dioxide. The method for manufacturing a halftone type phase shift mask blank according to claim 1, wherein: