JPS5824143A - Photomask - Google Patents

Abstract

PURPOSE:To prevent the sticking of dust, dirt, etc. to a photomask obtd, by forming a thin light shielding film of metal or metallic oxide on a glass substrate, by forming an electrically conductive transparent film on the back side of the substrate to prevent the electrification of the photomask. CONSTITUTION:Sputtering is carried hot in Ar plasma using 2 SnO2 plates 10 as cathodes and a quartz glass substrate 1 as an anode to form an electrically conductive transparent film of SnO2 on the whole surface of the substrate 1. A chromium oxide film or a chromium film is then formed on the surface of the substrate 1 by sputtering, vapor deposition or other method, and a resist layer is formed on the substrate and exposed to electron beams, X-rays, far ultraviolet rays or ultraviolet light. After patterning the resist layer by development, the unnecessary part of the chromium oxide film or the chromium film is removed by dry etching, wet etching or other method to obtain the desired photomask.

Description

[Detailed description of the invention] The present invention relates to a photomask.

Conventionally, a photomask is made by forming a chromium oxide film or a chromium film on a glass substrate by sputtering or vapor deposition, and then forming a resist layer on the substrate.

The resist layer is exposed to electron beam, X-rays, deep ultraviolet light, ultraviolet light, etc., and then the resist layer is patterned.

A node mask is formed by removing unnecessary portions of the chromium film and chromium llide film by dry etching, wet etching, etc.

Furthermore, when using a photomask, if a mask drying plate or wafer is exposed to one layer, the pattern will be destroyed by static electricity, so as shown in Figure 1, a transparent conductive film of SnO
, In04, etc., are known.

In the figure, 1 is a glass substrate and 2 is a transparent conductive film.

3 is chromium oxide and chromium film. .

However, as shown in Figure fa1, although photomasks can prevent charge-up due to valence particles during electron beam inspection, glass substrates made of quartz glass etc. are generally not charged because a transparent conductive film is not formed on the back surface of the substrate. Therefore, dirt, dust 4, etc. tend to adhere to the back side of the substrate, causing defects when used for pattern formation.

Also, when processing the 7-oto mask in vacuum by electron beam exposure, vapor deposition, dry etching, etc.

As a chuck for holding a photomask, a mechanical chuck, an electrostatic chuck that uses electrostatic force, and the like are known.

Mechanical chucks are undesirable because their chucking claws cover part of the surface of the printed circuit board. Further, the chucking force is only -sK, which may cause damage.

On the other hand, an electrostatic chuck is advantageous because it uses electrostatic attraction as its principle and can be used even in a vacuum, does not require chucking or gripping claws, and applies the chucking force uniformly. An electrostatic chuck that electrostatically chucks a photomask made of an insulating glass substrate is shown in Fig. 2(a).
A device having a pair of comb-shaped electrodes 5 and 6 as shown in FIG. 2(b) is used.

Figure K2 (a) is a sectional view, and Figure 2 (1)) is a plan view. F is an insulating material. 8 is a DC power supply.

This company creates a strong electric field by making the distance between the pair of electrodes 4 and 5 extremely narrow, thereby polarizing the object 9 and creating an attractive force between it and the electrodes. Although it can be applied to both conductive and insulating materials,
The drawback is that the adsorption force is weak when adsorbing glass substrates such as photomasks.

The present invention was made in view of the above-mentioned drawbacks, and provides a photomask having a transparent conductive film on at least the back surface of the substrate in a photomask in which a thin film of metal or metal oxide is provided on a glass substrate. It is something to do.

The present invention will be explained below with reference to the drawings.

FIG. 3 is a cross-sectional view of the manufacturing process of the photomask of the present invention.

As shown in Fig. 3(a), an algo ypj with two 8n02 plates 1o as cathodes and a quartz glass substrate 1 as an anode.
Sputtering is performed on the glass substrate surface.
Forms 5notlil (about 1aooX).

1 is a vacuum bell jar, and 12 is a high frequency power source.

In addition, transparent conductive films such as 8nO1, engineering no.
It can also be formed by reactive sputtering of x, evaporation of sno, or the like.

Furthermore, an alcohol solution of Sn, In-based organometallic compound material, etc. is immersed in a spin cord or solution, and after the coating film is formed, an oxidation heat treatment is performed at 300 to 8001:8 degrees.
A transparent conductive film such as nO1jnol may be formed. In the present invention, since a conductive film having good adhesion to a glass substrate can be obtained, a transparent conductive film was formed by a sputtering method or a tarinog method.

FIG. 3(b) is a sectional view of the step of forming a chromium layer on the glass substrate, and FIG. 3(c) is a sectional view of the step of exposing the resist layer on the chromium layer. Chromium layer ray acid (II, chromium layer and c
It may also include an r layer. Figure 3(b), 5 at (0)
゜6 is a pair of electrodes; 13 is the Or beam for vapor deposition.

3 is an Or, 14 resist layer deposited on the substrate.

14' is an exposed portion of the resist layer, and 15 is an energy beam for exposure.

In either case, since the glass substrate 1 has a conductive transparent conductive film 2 formed on the back surface of the substrate, a voltage of 1000 to 500071i[ is applied to the threshold of the pair of plane electrodes 5.6 through the insulator 7. By this, 8nO facing the electrodes 5 and 6
It is considered that a capacitor is formed between each transparent conductive film 2, and the glass substrate 6 is strongly attracted to the electrostatic check A.

Compared to the conventional case where the glass substrate is simply adsorbed,
Alternatively, compared to the case where a transparent conductive film is formed only on the surface of a glass substrate with a thickness of about 1 to 3 m+j, the electrostatic adsorption force is reduced to about 7 by forming a transparent conductive film on the back side of the glass substrate as in the present invention. It has become twice as strong.

In this example, since 8nO1 was used as a transparent conductive film as the conductive film on the back surface of the substrate, it can be used for exposure as is even after forming a photomask.

Furthermore, the photomask of the present invention can prevent charging by attaching it to the surface of a glass substrate.

Dust, dust, etc. can be prevented from adhering to the photomask, contributing to the manufacturing yield of semiconductor devices.

In this embodiment, an example is given in which Snug is used as the transparent conductive film.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a conventional photomask, FIG. 2 is a cross-sectional view and a plan view of a comb-shaped electrostatic chuck, and FIG. 3 is a cross-sectional view of the manufacturing process of the photomask of the present invention. 1: quartz glass substrate, 2°: transparent conductive film, 3 nichrome layer, 4: dust, dust, 5, 6: electrode, ): exquisite material, 8: DC power supply, 10: 5n04 anode. 11: Vacuum bell jar, 12: RIP power supply, 13 Nichrome beam, 14 Niresist, 15: ll light energy (b) No. 312I (a)

Claims (1)

[Claims] 1. A photomask comprising a reflective thin film of metal or metal oxide on a glass substrate, the photomask having a transparent conductive film at least on the back surface of the substrate.