JP3064962B2 - Halftone phase shift mask, mask blanks thereof, and method of manufacturing halftone phase shift mask and defect correction method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a halftone phase shift mask, a halftone phase shift mask blank, a method of manufacturing a halftone phase shift mask, and a defect of the halftone phase shift mask used in a lithography process of manufacturing a semiconductor integrated circuit. It relates to the correction method.

[0002]

2. Description of the Related Art With the increase in the degree of integration of semiconductor integrated circuits, miniaturization of circuit patterns has been rapidly progressing. On the other hand, a photolithography technique using a projection exposure apparatus has a resolution limit due to the wavelength of a light source.

In recent years, in order to improve resolution, a phase shift mask for forming a pattern on a photomask with a phase member has been actively developed.

Until now, various types of phase shift masks have been proposed.
The halftone phase shift mask described in
A mask pattern is composed of two types, an opening and a halftone phase shift unit. Since the structure is simple, the use thereof in the production of semiconductor integrated circuits has been started.

As shown in FIG. 4, a halftone phase shift mask in which the resolution is further improved by adding a light shielding portion is disclosed in Japanese Patent Application Laid-Open No. 7-128840.

Hereinafter, this prior art will be described with reference to FIG.

FIG. 4A is a sectional view of the halftone phase shift mask. A translucent phase shift film 2 and a light shielding film 4 are patterned in a predetermined shape on a transparent substrate 1 to form an opening 6, a translucent phase shift portion 8 and a light shielding portion 9.

FIG. 4B shows the amplitude of light transmitted through the halftone phase shift mask. Compared with the amplitude of the light transmitted through the opening 6 where the transparent substrate 1 is exposed, the amplitude of the light transmitted through the translucent phase shift unit 8 is attenuated and the phase is inverted. Further, the light shielding portion 9 does not transmit light.

When this light is projected on a wafer through a lens, the phase is inverted at the boundary between the opening 6 and the translucent phase shift section 8 as shown in FIG. Becomes almost zero. Therefore, the spread of the light intensity distribution is suppressed, and a high-resolution pattern can be transferred to the photoresist film.

Next, a method of manufacturing the halftone phase shift mask of FIG. 4 will be described with reference to FIG.

First, a translucent phase shift film 2 is formed on a transparent substrate 1 by sputtering. This is, for example, an oxynitride MoSi film having a thickness of about 180 nm and a wavelength of 3 nm.
The transmittance at 65 nm is about 8%. Further, a light-shielding film 4 is formed thereon by sputtering, for example, Cr. After forming a halftone phase shift mask blank (a material (base material) for manufacturing a halftone phase shift mask) in this manner, a resist film 5 is applied as shown in FIG.

Next, in FIG. 5B, a region to be an opening is exposed by an electron beam (indicated by an arrow).

Next, referring to FIG. 5C, using the patterned resist film 5 as a mask, the light-shielding film 4 is removed by wet etching, and the halftone phase shift film 2 is removed by dry etching to form the opening 6. Is formed.

Next, in FIG. 5D, the resist film 5 is peeled off.

Next, in FIG. 5E, a resist film 7 for patterning the light shielding film is applied.

Next, in FIG. 5F, electron beam exposure is performed as shown by the arrow.

Next, in FIG. 5 (G), the light-shielding film 4 is selectively removed by etching using the patterned resist film 7 as a mask.

Next, in FIG. 5H, the resist 7 is peeled off to complete a halftone phase shift mask in which the translucent phase shift portion 8 and the light shielding portion 9 are formed by patterning.

[0019]

In a halftone phase shift mask having a two-layer structure of a light-shielding film and a translucent phase-shift film, correction is made when a light-shielding film defect 10 as shown in FIG. Is difficult. That is, the light-shielding film defect 10
When the focused ion beam 11 is irradiated to remove
As shown in FIG. 6B, the translucent film damage 12 occurs in the underlying translucent film. If such damage occurs, the transfer characteristics of the halftone phase shift film will be impaired.

Japanese Patent Application Laid-Open No. 3-132662 discloses a method for correcting a light-shielding film defect in the case of a normal light-shielding mask.
The method of forming a buffer film 14 made of MoSi under a light-shielding film 4 made of chromium as shown in FIG. The light shielding film defect 10 is corrected by the focused ion beam 11 (FIG. 7).
(A)) and buffer film damage 15 on the underlying buffer film 14
(FIG. 7B). Thereafter, when dry etching is performed with CF ₄ gas, the MoSi film below the light-shielding film defect is selectively removed. This method is effective in the case of a light shielding mask, but in the case of a halftone phase shift mask having a two-layer structure of a light shielding film, a translucent phase shift film, the translucent phase shift film itself is made of MoSi or the like. Therefore, etching selectivity with the buffer film cannot be obtained.

Accordingly, an object of the present invention is to provide a halftone phase shift mask, a halftone phase shift mask blank, and a halftone phase shift mask that can correct a light-shielding portion film defect without impairing the resist pattern transfer characteristics of the halftone phase shift mask. And a method for correcting a halftone phase shift mask.

[0022]

In order to achieve the above object, a halftone phase shift mask according to the present invention comprises: an opening for exposing a surface of a transparent substrate; A translucent phase shift unit in which a translucent phase shift film that attenuates the amplitude while being inverted is laminated on the transparent substrate, and a light shielding unit that blocks light by laminating a light shielding film on the translucent phase shift film. And an intermediate thin film having etching selectivity with respect to both the translucent phase shift film and the light shielding film between the translucent phase shift film and the light shielding film.

Particularly preferably, in the halftone phase shift mask of the present invention, the intermediate thin film is made of silicon oxide.

In the halftone phase shift mask blank of the present invention, a translucent phase shift film, an intermediate thin film and a light shielding film are laminated on a transparent substrate, and the intermediate thin film is formed of the semitransparent phase shift film and the light shielding film. Both have etching selectivity.

Particularly preferably, in the halftone phase shift mask blangs of the present invention, the intermediate thin film is made of silicon oxide.

The method of manufacturing a halftone phase shift mask according to the present invention includes a first step of laminating a translucent phase shift film, an intermediate thin film, and a light shielding film on a transparent substrate; A second step in which a part of the intermediate thin film and a part of the translucent semi-transparent phase shift film are sequentially removed by exposure and etching to form an opening; The method includes a third step of forming a transparent phase shift portion and a fourth step of removing an intermediate thin film on the translucent phase shift portion by etching.

Further, the method for correcting a defect of a halftone phase shift mask according to the present invention is characterized in that, in the third step of the method for manufacturing a halftone phase shift mask, when a black defect occurs without removing the light-shielding film, The method is characterized in that the black defect is removed by a focused ion beam or a laser blow between the third step and the fourth step.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention.
1 shows a cross-sectional view of a halftone phase shift mask.

In FIG. 1, a translucent phase shift film 2 is deposited on a transparent substrate 1. Translucent phase shift film 2
Is a single layer or multilayer composed of chromium, chromium oxide, chromium oxynitride, chromium fluoride, molybdenum silicide, molybdenum silicide oxide, molybdenum silicide oxynitride, molybdenum silicide fluoride, etc. It is a membrane. At this time, the condition required for the translucent phase shift film 2 is that the transmittance of the exposure light is 1 to 30% and the phase of the transmitted exposure light is 180%.
Need to be converted.

An intermediate thin film 3 is formed between the translucent phase shift film 2 and the light shielding film 4.

The light-shielding film 4 is a single-layer or multi-layer film made of chromium, chromium oxide, chromium nitrate, or the like.

The intermediate thin film 3 is a halftone phase shift film 4
In addition, it is necessary to have etching selectivity with respect to the light shielding film 2. For this purpose, for example, silicon oxide having a thickness of about 5 nm may be formed as an intermediate thin film by sputtering. Silicon oxide can be etched with an alkaline aqueous solution such as sodium hydroxide. At this time, the transparent substrate 1 made of synthetic quartz is also slightly etched. 365n when etched 5nm
The phase of the light of m is shifted by about 2.5 degrees. When determining the film thickness of the translucent phase shift film, it is necessary to consider the phase difference caused by engraving the substrate in the opening 6.

FIG. 2 shows a second embodiment of the present invention.
FIG. 4 shows a process chart of a method for manufacturing a halftone phase shift mask.

First, a translucent phase shift film 2, an intermediate thin film 3, and a light shielding film 4 are formed on a transparent substrate 1 by sputtering. The translucent phase shift film 2 was made of oxynitride of molybdenum silicide, the intermediate thin film 3 was made of silicon oxide, and the light shielding film was made of chromium. After forming a halftone phase shift mask blank (a material (base material) for manufacturing a halftone phase shift mask) in this manner, a resist film 5 is applied as shown in FIG.

Next, in FIG. 2B, a region to be an opening is exposed by an electron beam (indicated by an arrow).

Next, referring to FIG. 2C, the light-shielding film 4 is removed by dry etching with a chlorine-based gas using the pattern of the resist film 5 from which the portion irradiated with the electron beam has been removed as a mask. The opening 6 is formed by removing the intermediate thin film 3 and the halftone phase shift film 2 by dry etching with a gas.
(C)).

Next, in FIG. 2D, the resist film 5 is peeled off.

Next, in FIG. 2E, a resist film 7 for patterning the light shielding film is applied.

Next, in FIG. 2F, electron beam exposure is performed again as indicated by the arrow.

Next, in FIG. 2G, the light-shielding film is removed by dry etching with a chlorine-based gas using the pattern of the resist film 7 from which the portion irradiated with the electron beam has been removed as a mask.

Next, in FIG. 2H, the resist 7 is peeled off.

Next, in FIG. 2I, the halftone phase shift mask is completed by removing the intermediate thin film 3 by wet etching with a sodium hydroxide solution.

FIG. 3 shows a process chart of a method for correcting a defect of a halftone phase shift mask as a third embodiment of the present invention.

The defect inspection is performed at the stage shown in FIG. 2H of the process chart of the method for manufacturing the halftone phase shift mask shown in FIG. As shown in FIG. 3A, when a light-shielding film defect 10 occurs in the light-shielding film 4, the light-shielding film defect 10 is removed using a focused ion beam 11 using Ga ions. The use of the focused ion beam causes intermediate thin film damage 13 in the lower intermediate thin film 3 (FIG. 3B).

This damage is removed at the same time as the intermediate thin film 3 is removed by wet etching using a sodium hydroxide solution corresponding to FIG. 2 (I) in the process chart of the method for manufacturing the halftone phase shift mask shown in FIG. Is done.

In this way, the defect correction of the halftone phase shift mask is completed as shown in FIG.

In the method of repairing a defect of a halftone phase shift mask according to the present invention, a focused ion beam using Ga ions is used for repairing the defect. Various methods such as laser blowing using a beam can be used.

[0049]

According to the present invention, it is possible to correct a light-shielding portion defect of a halftone phase shift mask having a two-layer structure of a light shielding film and a halftone phase shift film without leaving damage to the mask after the correction. it can.

When a halftone phase shift mask having a defect corrected is used, the resolution and the depth of focus of the pattern on the entire surface of the mask are improved. As a result, a finer pattern can be formed, and a semiconductor integrated circuit with a higher degree of integration can be manufactured.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a halftone phase shift mask according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a method of manufacturing a halftone phase shift mask according to a second embodiment of the present invention in the order of steps.

FIG. 3 is a sectional view illustrating steps of a method for correcting a defect of a halftone phase shift mask according to a third embodiment of the present invention.

4A and 4B are diagrams illustrating the principle of a conventional two-layer halftone phase shift mask, wherein FIG. 4A is a cross-sectional view of the halftone phase shift mask, FIG.
(C) is a diagram showing a light intensity distribution on a wafer.

FIG. 5 is a sectional view showing a method for manufacturing a conventional halftone phase shift mask in the order of steps.

FIG. 6 is a cross-sectional view showing the steps of a conventional halftone phase shift mask defect correction method in order.

FIG. 7 is a cross-sectional view showing steps of a conventional method of correcting a defect of a light-shielding mask in order.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 Translucent phase shift film 3 Intermediate thin film 4 Light shielding film 5 Resist film 6 Opening 7 Resist film 8 Translucent phase shift part 9 Light shielding part 10 Light shielding film defect 11 Focused ion beam 12 Translucent film damage 13 Intermediate thin film damage 15 Damage to buffer film

Claims (6)

(57) [Claims] 1. A semi-transparent substrate comprising: an opening for exposing the surface of a transparent substrate; and a semi-transparent phase shift film for attenuating the amplitude while inverting the phase of the transmitted exposure light with respect to the opening. A transparent phase shift unit, and a light shielding unit that blocks light by laminating a light shielding film on the semitransparent phase shift film, wherein the semitransparent phase shift film is between the semitransparent phase shift film and the light shielding film. A halftone phase shift mask comprising an intermediate thin film having etching selectivity with respect to both the light-shielding film and the light-shielding film. 2. The halftone phase shift mask according to claim 1, wherein said intermediate thin film is made of silicon oxide. 3. A translucent phase shift film, an intermediate thin film and a light shielding film are laminated on a transparent substrate, and the intermediate thin film has an etching selectivity with respect to both the semitransparent phase shift film and the light shielding film. Characterized halftone phase shift mask blanks. 4. The halftone phase shift mask blank according to claim 3, wherein said intermediate thin film is made of silicon oxide. 5. A first step of laminating a translucent phase shift film, an intermediate thin film, and a light shielding film on a transparent substrate, and a step of forming a part of the light shielding film, a part of the intermediate thin film, and the semitransparent phase shift film. A second step of forming an opening by sequentially removing a part by exposure and etching, and a third step of forming a translucent phase shift part by removing a part of the light-shielding film by exposure and etching; And a fourth step of removing the intermediate thin film on the translucent phase shift portion by etching. 6. The third step and the fourth step when a black defect occurs without removing the light-shielding film in the third step of the method of manufacturing a phase shift mask according to claim 5. Wherein the black defect is removed by a focused ion beam or a laser blow.