JPS58204534A - Mask for x-ray lithography - Google Patents

Abstract

PURPOSE:To obtain a mask for X-ray lithography which is reduced in alignment errors, excellent in chemical resistance and transparent to even a visible light, by employing a thin film constituted by diamond or a mixture of diamond and amorphous carbon. CONSTITUTION:Since diamond has the highest thermal conductivity in the known materials, the employment of diamond makes it possible to quickly transmits to the outside the heat absorbed by an X-ray absorber, such as Au or the like, which is formed on a transparency, and minimize the rise in temperature of a mask due to exposure. As a result, it is possible to prevent any alignment error of a pattern. Moreover, since the mask is constituted by a transparent thin film, a visible light can be employed for alignment. To obtain an X-ray lithography mask, it is effective to form a transparent film constituted by diamond and amorphous carbon by employing magnetron sputtering or ion beam sputtering. Thus, a mask is obtained which has a sufficiently high film strength and an excellent light-transmitting property.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ring 2-fi mask used in the manufacture of semiconductor devices, and more particularly to the structure of an X-ray phosphorography mask.

The properties required for a mask for X#l phosphorography are 1)
The linear absorption coefficient of the Xi transparent body is small, 1f) The positional stability of the X-ray transparent body is excellent, 111) Chemical resistance.

It has excellent moisture resistance, and IV) is durable and easy to produce. Furthermore, assuming that the mask-way 71 is to be carried out using an acousto-optic method, it is desirable to use a material that is not only transparent to X-rays but also highly transparent to visible light.

Conventional X scarlet lithography mask materials include S L,
A number of materials have been considered, such as 8+sNa, BN, Ti, polyimide, etc. These materials do not simultaneously satisfy all of the properties required for the above-mentioned masks;
There are pros and cons.

Among these properties, it is an object of the present invention to provide a mask that has excellent positional stability and chemical resistance, and is also transparent to visible light. In the present invention, a thin film of diamond is formed to achieve all of this.

As is well known, diamond is one of the materials with the highest thermal conductivity among known materials, and by using diamond, an X-ray absorber such as Au formed on the transparent material can absorb X-rays. The heat absorbed by the insect repellent can be quickly transferred to the outside of the thread,
Therefore, it is possible to suppress the increase in magnetic field of the mask due to XM light, and to minimize the pattern positional deviation due to thermal expansion. Furthermore, since it is a transparent thin film, a visible light source such as a He-Ne laser can be used for alignment.

Conventionally, carbon vapor deposition was carried out in a vacuum using a carbon electrode in an arc group, but with this method, the carbon thin film formed was a mixture of amorphous carbon and graphite, and a film of 100 Å or more was The color changed from dark brown to black, and the light transmittance was poor, and a film with sufficient strength could not be obtained, so it could not be used as a mask for X-ray radiation.

In the present invention, a transparent film made of diamond and rectangular carbon is formed by using a magnetron sputtering method or an ion beam sputtering method as a vapor deposition method.
Wl) Used as a mask for lithography. The following is a detailed explanation based on examples.

FIG. 1 shows a first embodiment of the present invention, in which 1 is a lead, 2 is an anode, 3 is a substrate, 4 is a target, 5 is a magnet, 6 is a cathode, and 7 is a vacuum system.

As shown in FIG. 1, this is a method in which a perpendicular electromagnetic field is formed in the vicinity of the target 4 used in the planar magnetron sputtering method to generate high-density plasma.
~ A molded bluff eye trap was used as the target, and argon or nitrogen was used as the sputtering gas. (111)S for base &3
i (100)Si or IR-polished silica glass was used.

A carbon film with a thickness of 0.2 to 3 μm was formed on the substrate by sputter deposition.

FIG. 2 shows a second embodiment of the present invention, in which 21 is a filament, 22 is an anode, 23 is a grid electrode, 24 is a neutralizer, 25 is a target, 26 is a substrate, 27 is an N,
28 is a vacuum exhaust system, and 29 is a vacuum system.

The ion beam sputtering apparatus shown in FIG. 2 consists of an ion source section with a relatively low vacuum and a sputter section with a relatively low vacuum. The ion source section was set at a potential of 100 OV with respect to ground. A grid electrode 23 is provided and grounded for extracting ions from the ion beam to the sputtering section. The ions accelerated in this manner strike the target 25 and are deposited on the substrate 26.

As in the first embodiment, molded graphite T- was used as the target, and N! was used as the sputtering gas. , and the board is (
111)8i, (100)Si and quartz plates were used.

The gas pressure t'' is 10-'forr or less, and 0.
A carbon fiber membrane with a thickness of 5 to 3 μm was formed.

Table 1 summarizes the results of measuring the crystal chemical properties (x) of the films formed in the first and second examples by reflection electron diffraction, and the visual color A after etching the substrate.

D=diamond-shaped, amorphous G: graphite-type As can be seen from this table, the carbon films formed in both Examples 1 and 2 are highly transparent films containing diamond-like carbon as a main component.

In the first equation, the inequality sign indicates the magnitude relationship of the component ratio, for example, D)A indicates that if D is A, there is more.

Figure 3 shows an embodiment of ig3 of the present invention, with (11
1) For 8131k A A method for making a 2 μm thick carbon film 32 is used as an X-ray phosphorography mask as an example. - From above, T133 is formed to a thickness of po and oi .mu.m by vapor deposition, and a resist pattern 34 is formed using a conventional method. Using this as a patterning mask, gold plating was performed to form a sparrow pattern 35 with a thickness of about 0.5 μm, and the Si substrate 3 was devised to protect the patterned surface.
1 was removed from the back side using a mixed solution of HF + HNOs + CH, COOH to obtain a mask.

In order to clarify the effect of the present invention, the mask obtained in the third embodiment was irradiated with X- of 8.34 wavelength and the temperature rise was investigated. The X-ray intensity on the mask surface is 1 mw/ra2
And so. The gold pattern was made into a sphere occupying 40% of the mask surface, and the mask temperature rise after 2 minutes of X-ray irradiation in vacuum, 1'l'orrlle, and air was investigated, and it was found that in vacuum it was 0. Although there was an increase of about IC, ITOrrHe
In air, the temperature was below the lower measurement limit (O, OSo). By the way, when we investigated the temperature rise of existing polyimide with a thickness of 3 μm under similar conditions, we found that the temperature rise was about 1.2 CX in vacuum and about 0.2 C in air.

This proves that the carbon mask, whose main composition is diamond, has small temperature changes and high dimensional stability.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the principle of a planar magnetron sputtering device to which the present invention is applied, Figure 1@2 is a diagram showing the principle of an ion beam sputtering device to which the present invention is applied, and Fig. 3 is a diagram showing a mask making process to which the present invention is applied. I'll go. 11 Figure 'lil! 12I21 Kaya 3 Figure

Claims (1)

[Claims] A Xi milligraphy mask characterized by having a thin film made of diamond or a mixture of diamond and amorphous carbon as an X-ray transmitter.