JPH06342208A - Pellicle for protecting mask - Google Patents

Abstract

PURPOSE:To prevent the failure of the pellicle by the change of the shape of a peloicle film with a fluctuation in atm. pressure and to improve reliability by mounting the pellicle film at a prescribed angle deviated from parallel with a photomask on a pellicle film. CONSTITUTION:The pellicle film 12 is mounted on the pellicle frame 11 by varying the height on a set of opposite two sides of the equilateral pellicle frame 11 at about 0.5 to 3mm and providing the pellicle film 12 with the specified angle deviated from the parallel with the photomask 13. The pellicle film 12 which is flat under the atm. pressure attains a projecting state 12a when the arm. pressure outside the pellicle drops but the pellicle film 12a does not rise higher than the highest point of the pellicle frame 11 with an ordinary change in the atm. pressure and the damage of the pellicle film 12a in the projecting state by coming into contact with the case of the photomask does not arise. The recessed pellicle film 12b does not sink lower than the lowest front surface of the pellicle frame 11 and the dust, etc., sticking onto the pellicle film 12b are not transferred onto a wafer even the outside atm. pressure rises.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pellicle for mask protection used in a photolithography process in the manufacturing process of semiconductor devices.

[0002]

2. Description of the Related Art A semiconductor device manufacturing process requires a photolithography process for forming a pattern by transferring a pattern of a photomask onto a semiconductor wafer. If foreign matter such as dust adheres to the pattern surface of the photomask in this step, it is also transferred to the wafer, pattern defects occur, and as a result, the manufacturing yield of semiconductor devices decreases.
In order to prevent such a situation, conventionally, a mask protecting pellicle has been used.

FIG. 2A is a perspective view schematically showing a conventional mask protecting pellicle, and 21 is a pellicle frame.
Reference numeral 22 is a pellicle film, and 23 is a photomask. On the upper surface of the pellicle frame 21, a translucent pellicle film 22 is stretched with an adhesive. An adhesive is also applied to the lower surface of the pellicle frame 21, and the pellicle frame 21 is mounted on the photomask 23. As shown in FIG. 2A, the conventional mask protecting pellicle has a pellicle frame 2
Since the surface on which the pellicle film 22 of No. 1 is mounted is flat, the pellicle film 22 is stretched flat.

[0004]

FIG. 2B is a schematic diagram of FIG.
It is sectional drawing of the bb part of (A). As shown in FIG. 2B, the conventional mask protecting pellicle is flat like the pellicle film 22 when the atmospheric pressure outside the pellicle is normal pressure, but when the atmospheric pressure outside the pellicle becomes lower than inside the pellicle. , A convex shape like the pellicle film 22a. For this reason, the convex pellicle film 22a may be touched by the case of the photomask and may be damaged or broken, so that the pellicle's original function of preventing adhesion of dust or the like to the pattern surface of the photomask cannot be fulfilled. there were.

Although the above problem can be solved by simply lowering the height of the pellicle frame 21, when the atmospheric pressure outside the pellicle rises and the pellicle film 22b becomes concave like the pellicle film 22b, the pellicle film 22b and the photomask 23 are separated. There is a problem in that the distance becomes short and dust or the like on the pellicle film is transferred to the wafer.

An object of the present invention is to provide a highly reliable mask protecting pellicle which prevents damage to the pellicle film due to a change in the shape of the pellicle film due to a change in atmospheric pressure outside the pellicle.

[0007]

A mask protecting pellicle according to the present invention is characterized in that a pellicle film is attached to a pellicle frame with a certain angle deviated from parallel to a photomask. .

[0008]

EXAMPLES FIGS. 1A and 1B are schematic views of a mask protecting pellicle of an example. Of these, (A) is a perspective view and (B) is a cross-sectional view taken along the line bb of (A).

The present embodiment differs from the conventional example of FIG. 2 in that among the quadrilateral pellicle frames 11, the height of one pair of pellicle frames facing each other differs by about 0.5 to 3 mm. That is, the pellicle film is attached to the pellicle frame with a certain angle deviated from the parallel to the photomask. The method of installing the pellicle film 12 and the photomask 13 on the pellicle frame 11 is the same as in the conventional example.

Next, according to FIGS. 1 (A) and 1 (B),
The operation of the embodiment will be described.

When the outside of the pellicle is at normal pressure, the shape of the pellicle film 12 does not change, and the pellicle film 12 becomes flat like the pellicle film 12 of FIG.

When the atmospheric pressure outside the pellicle is lowered, the pellicle film 12 is in a convex state like the pellicle film 12a of (B). It won't be expensive. Therefore, the convex pellicle film 12a is not touched or damaged by the case of the photomask.

When the atmospheric pressure outside the pellicle rises, the pellicle film 12 becomes concave like the pellicle film 12b of FIG. 1 (B). However, under normal atmospheric pressure changes, the pellicle film 12b does not become lower than the lowest upper surface of the pellicle frame 11. Therefore, if the height of the lower side of the pellicle frame 11 is properly selected, the concave pellicle film 12b is formed.
Dust and the like adhering to the surface of the wafer will not be transferred onto the wafer.

In the above embodiment, the shape of the pellicle frame is a quadrangle, but the shape is not limited to this and may be a ring shape or the like.

[0015]

According to the present invention, since the pellicle film is mounted on the pellicle frame with a certain angle deviated from parallel to the photomask, the pellicle film changes due to a change in shape of the pellicle film due to a change in atmospheric pressure outside the pellicle. It is possible to provide a highly reliable mask protection pellicle that prevents damage.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a mask protection pellicle according to an embodiment of the present invention.

FIG. 2 is a diagram schematically showing a conventional example.

[Explanation of symbols]

 11 Pellicle frame 12, 12a, 12b Pellicle film 13 Photomask

Claims (1)

[Claims] 1. A pellicle for mask protection, wherein a pellicle film is mounted on a pellicle frame with a certain angle deviated from parallel to a photomask.