JP3333623B2 - Method for producing mask membrane material for X-ray and electron beam lithography - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION Masks for X-ray and electron beam lithography which have a small change in stress even when irradiated with a high energy beam such as a high energy electron beam or synchrotron radiation and have good visible light transmittance. The present invention relates to a method for producing a membrane material.

[0002]

2. Description of the Related Art With the miniaturization of pattern formation in semiconductor devices, X-ray and lithography have been
And electron beam lithography are the most promising. X
The important properties required for the X-ray transmission film of a mask used in X- ray and electron beam lithography (in other words, a support film of an X-ray absorber, hereinafter abbreviated as a membrane) are as follows. Must be smooth and have practical strength without scratches or pinholes. (2) It has visible light transmittance necessary for high-precision alignment (positioning). (3) It has good chemical resistance and moisture resistance, and is not easily damaged in an etching step or a cleaning step. (4) Withstand irradiation with a high energy beam such as a high energy electron beam or synchrotron radiation. Conventionally, as the material of the X-ray and electron beam Risofurafi mask membrane, boron-doped Si, Si C, Si _{3
N 4, Si C / Si 3} N 4 hybrids have been proposed. Of these Si C / Si ₃ N ₄ hybrid film has a high visible light transmittance and high elasticity, a material excellent in a higher energy beam irradiation resistance.

However, until now Si C / Si ₃ N ₄ hybrids film by mixing each powder the Si ₃ N ₄ and Si C hot pressing, pressureless sintering, those sintered by microwave sintering, etc. Was used as a target material (see Japanese Patent Application Laid-Open No. 03-196149). This target is the decomposition temperature of Si ₃ N ₄
Sintered at 1600 ° C to 1700 ° C, which is lower than 1800 ° C, while the normal sintering temperature of SiC is 2200 ° C,
At about 00 ° C., sufficient bonding force between particles cannot be obtained because SiC is not sintered. Therefore, SiC, SiC and SiC
C and Si ₃ N ₄ are merely compacts that are weakly bonded by hot pressing and have a low density of 1.68 g / cm ³ ,
The target easily absorbed impurities such as water and air, and the bulk oxygen content was as high as 1.20% by weight. Although a membrane obtained by using this target can be formed by a sputtering method, there is a disadvantage that impurities in the target are also mixed. SIMS
According to the analysis (abbreviation for Secondary Ion Mass Spectrometry), the amount of oxygen in the film was 4.0 × 10 ²⁰ atoms / cm ³ , and the amount of hydrogen in the film was 4.0 × 10 ²⁰ atoms / cm ³ . This is a high-energy beam irradiation resistance on very unfavorable value (Arakawa, other: the 53rd Society of Applied Physics Lecture Proceedings No.2 (1992) P _· 491, Arakawa, other: 40th Applied Physics relationship Alliance Lectures No.
It is a _{2 (1993) P · 508)} .

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to reduce the oxygen and hydrogen content of a film, to provide a high energy electron beam or SOR.
X-ray and electron beam lithography with excellent high-energy beam resistance that does not change in stress or visible light transmittance even when irradiated with a high-energy beam such as light (synchrotron radiation) A method for manufacturing a mask membrane material.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies with a focus on a target material of a sputtering film forming method in order to solve the above problems, and as a result, the present invention has been completed. place, by a sputtering method, the X-ray and the manufacturing method of the electron beam lithography mask membrane material made of it to form a hybrid film of Si C and Si ₃ N ₄ on the substrate, in contact with one another arrangement
And a plurality of targets each composed of a SiC molded body and a Si ₃ N ₄ molded body.

Hereinafter, the present invention will be described in detail. Si C /
When forming a Si ₃ N ₄ hybrid film by a sputtering method, the following target is used. Si ₃ N ₄ and Si
Separately hot pressing and C, respectively, composition atmospheric sintering, to prepare a sintering method using a microwave sintering or the like, corresponding to each of the sintered body blocks a predetermined Si C / Si ₃ N ₄ ratio The ratios, sizes and shapes (see FIG. 1) are finely divided and alternately arranged (see FIG. 2) so that each has a distribution as uniform as possible. At this time, each sintered body block
It is preferable to arrange them closely without any gap. The finer the number of divisions, the better the uniformity is increased. However, there is a limit in terms of workability, and each is preferably 30 or less. Further, sandwich method for bonding the respective blocks may be bonded directly bonded by sintering at a temperature lower than the decomposition temperature the Si ₃ N _4, other very small Si powder as a binder, the Si ₃ N ₄ It is also possible to sinter and join at a temperature below the decomposition temperature.

[0007] The molar ratio of Si C and Si ₃ N ₄ is 95: 5 to 3
0:70 is preferred. When Si C exceeds 95, the visible light transmittance shows a low value equivalent to that of Si C alone, and conversely, Si
If C is less than 30, the chemical resistance is unsatisfactory as well as that of Si ₃ N ₄ alone, which is not preferable. Si
Suitable molar ratios of C and _{Si 3 N 4, 80: 20~40} : 60
It is. In particular, in the case of 50:50, the film formation rate is high, and SiC
It is about twice that of a single case, which helps to improve productivity. It has been found that a membrane obtained by forming a film using this hybrid target has little oxygen and hydrogen as impurities and has excellent high energy beam resistance.

[0008]

EXAMPLES Hereinafter, embodiments of the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited to these. (Example) For sputtering, an RF magnetron sputtering device SPF-332H type (trade name, manufactured by Nidec Anelva)
Was used. The target is 4 inches in diameter and 5 mm thick
t, the composition ratio used was a _{Si C / Si 3 N 4 =} 1/1 ( molar ratio). Hereinafter, a method for producing a hybrid target will be described. First, a 4 inch diameter, 5 mmt thick S
An i ₃ N ₄ disk-shaped target was obtained by molding a metal silicon powder having a purity of 99.8% or more with a press machine, and reacting it at 1600 ° C. for 4 hours in a nitrogen gas atmosphere having a purity of 99.999% by volume. The density was 3.40 g / cm ³ and the oxygen content in the bulk was 0.16% by weight. Next, 15 such disk-shaped targets were cut out in a fan shape at a central angle of 18.4 °. For cutting, to reduce the cutting allowance φ
A 180 μm wire saw was used. Similarly, a SiC disk-shaped target was prepared by applying a SiC powder having a purity of 99.9% or more at 2200 ° C and 200k.
It was obtained by sintering under hot press conditions of gf / cm ² . Its density is
The amount of oxygen was 3.20 g / cm ³ and the amount of oxygen in the bulk was 0.07% by weight.
Fifteen of these were cut out in a fan shape at a central angle of 5.6 ° using a wire saw. The slurry used for cutting had an extremely small particle size, and the surface of the cut surface was about the mirror-polished surface, and Ra (center line average roughness) was about 1.2 nm. After washing these sintered bodies blocks, as in FIG. 2 Si ₃
N _4, 1700 after bonding adhesion to Si C by 15 alternately
C. and sinter-bonded to obtain a hybrid target, which was set in a target holder.

An Si gas wafer having a diameter of 3 inches and a thickness of 600 μm, both sides of which had been mirror-polished, was heated to 800 ° C., and an argon gas was flowed at a flow rate of 15 cc / min.
The stress of the film after film formation is 1 to 2 × 10 ⁹ d suitable for membrane formation
After adjusting the inside of the chamber to a pressure of 6.0 × 10 ^-2 Torr with a butterfly valve connected to the exhaust system so as to have a tensile stress of yn / cm ² , sputtering was performed for 10 to 15 minutes at a power of 2 W / cm ³ to obtain a film. the Si C / Si ₃ N ₄ hybrid film having a thickness of 1.0μm was prepared. XPS (X-rayPhotoelec)
tron Spectroscopy abbreviation) method results of elemental composition analysis, hybrid target Si C and Si ₃ N ₄
It was confirmed that the thin film was composed of Si ₁ C _0.2 N _0.7 having a composition close to the equimolar ratio of Next, when the amounts of oxygen and hydrogen in the film were measured by the SIMS method, 4.4 × 10 ¹⁸ a
toms / cm ³ and 4.0 × 10 ¹⁹ atoms / cm ³ . Next, this film was subjected to SOR light irradiation at 100 MJ / cm ³ to a membrane obtained by back etching a silicon substrate and opening a window to form a membrane. The results are shown in Table 1. From this, it was found that there was no damage by SOR light irradiation, and it was confirmed that the membrane material was extremely excellent in SOR light irradiation resistance.

(Comparative Example) For comparison, a diameter obtained by mixing an equimolar mixture of Si ₃ N ₄ powder having a purity of 99.9% or more and SiC powder having a purity of 99.9% or more by a hot press at 1700 ° C. and 200 kgf / cm ^2. 4
When a target having a thickness of 5 mm and a thickness of 5 mm was prepared and used to obtain a thin film by sputtering under the same conditions as in the example, the thin film showed a composition of Si ₁ C _0.2 N _0.7 and contained oxygen and hydrogen in the film. Measured the amount of each, 4.0 × 10 ²⁰ a
toms / cm ³ and 4.0 × 10 ²⁰ atoms / cm ³ . Further, this was made into a membrane under the same conditions as in the example, and 100 MJ / cm ³ of S
The results of the OR light irradiation are also shown in Table 1. It was found that the SOR light irradiation caused a decrease in stress and visible light transmittance.

[0011]

[Table 1]

[0012]

According to the present invention, it is possible to obtain a mask membrane having a very small amount of impurities in the film, particularly, oxygen and hydrogen. A mask membrane that is excellent in high-energy beam irradiation resistance with less stress fluctuation due to high-energy beam irradiation and a decrease in visible light transmittance is obtained. In two respects, its utility value is extremely high in industry.

[Brief description of the drawings]

FIG. 1 is a plan view showing an example of a hybrid target of the present invention.

FIG. 2 is a plan view showing another example of the hybrid target of the present invention.

[Explanation of symbols]

1 Si C shaped body 2 Si ₃ N ₄ moldings

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-196149 (JP, A) JP-A-4-17661 (JP, A) JP-A-3-56660 (JP, A) JP-A-4-196 15908 (JP, A) JP-A-53-17076 (JP, A) JP-A-3-34310 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/027 G03F 1 / 16

Claims (1)

(57) [Claims] 1. A SiC film is formed on a substrate by a sputtering method.
Forming a hybrid film of Si ₃ N ₄ and X 3
In the method for producing a mask membrane material for electron beam and electron beam lithography , a plurality of
A method for producing a mask membrane material for X-ray and electron beam lithography, comprising using a target composed of a SiC molded body and a Si ₃ N ₄ molded body.