JPH08114911A - Pellicle for photomask and photomask - Google Patents

Abstract

PURPOSE: To decrease the production rate of damages in a pellicle film for a photomask used for the production of semiconductor devices such as ICs when the pellicle film is attached to a holder of a photomask, and to prevent deposition of dust on the patterned surface of a photomask used for the production of semiconductor devices. CONSTITUTION: This pellicle for a photomask has such a constitution that a projecting part A from a pellicle film 54 is formed along the peripheral part of the pellicle film 54. For example, a protective cover 60 is attached to the outside of a pellicle frame 52 on a photomask 58 so that the upper face of the protective cover 60 is regarded as the projecting part A. Further, the photomask is produced by forming a pattern on one surface of a transparent substrate and sticking a transparent protective plate to the surface of the substrate to cover the pattern.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photomask pellicle and a photomask used for manufacturing a semiconductor device such as an IC.

[0002]

2. Description of the Related Art A projection exposure apparatus having a mask holder shown in FIGS. 5 and 6 is used as an exposure apparatus used in an exposure process for manufacturing a semiconductor device. FIG. 5 is a perspective view of the mask holder, and FIG. 6 is an enlarged sectional view. The mask holder 2 is composed of an inner holder 4 and an outer holder 6. First, the photomask 8 is attached to the inner holder 4, then the inner holder 4 is inserted into the outer holder 6, and then the inner holder 4 is inserted. The outer holder 6 is set in the projection exposure apparatus.

In a projection exposure apparatus, a pattern such as an IC is transferred onto a wafer by using a photomask. However, if dust is attached or scratched on the pattern surface of the photomask, these are left on the wafer as they are. Is transcribed to. Therefore, conventionally, as shown in FIGS. 5 and 6, the pellicle 10 is attached to the pattern surface of the photomask 8. The pellicle 10 has a ring-shaped pellicle frame 12 made of aluminum or the like, and a transparent pellicle film 14 made of nitrocellulose or the like attached to the pellicle frame 12 so as to cover the front end side opening thereof,
The base end of the pellicle frame 12 is attached to the pattern surface of the photomask 8 with an adhesive 16.

The pellicle prevents dust from adhering to the pattern surface of the photomask. By attaching the pellicle to the photomask, pattern defects such as ICs caused by the dust adhering to the pattern surface are prevented. be able to. The reason will be described with reference to FIGS.
In the figure, 8 is a photomask, 18 is a chrome pattern of the photomask 8, 20 is a wafer, and 22 is a resist applied on the wafer 20.

When the pellicle is not attached to the mask 8 as shown in FIG. 7, the dust 24 adheres to the pattern surface of the mask 8, so that the mask-wafer distance m and the dust-wafer distance n are equal. Then, the dust 24 is focused on the wafer surface and transferred onto the wafer (the dust transfer portion is indicated by 26 in the figure).

On the other hand, when the pellicle 10 is attached to the photomask 8 as shown in FIG. 8, the dust 24 adheres to the pellicle film 14, and therefore the mask-wafer distance m and the dust-wafer distance n. Is different from. Therefore, the dust 24 is not focused on the wafer surface and is out-focused, so that it is not transferred onto the wafer. However, there is a limit to the size of dust that is out of focus, and large dust is transferred. Further, since the scratches on the pellicle are usually large, they are often transferred.

[0007]

In the mask holder shown in FIGS. 5 and 6, when the inner holder 4 having the photomask 8 set therein is inserted into the outer holder 6, the pellicle 1
The pellicle film 14 of 0 is easily damaged. That is, in the inner holder 4, the total thickness of the photomask 8 and the pellicle 10 becomes relatively thick, whereas the distance between the side wall portions 6a, 6a of the outer holder 6 is relatively narrow. Specifically, in the inner holder 4, the total thickness of the mask and the pellicle is 6 mm.
In the outer holder, the distance between the side wall portions 6a, 6a is 14
It is about mm, and the gap between the side wall portion 6a and the pellicle film 14 is small. Therefore, when the inner holder 4 on which the photomask 8 is set is inserted into the outer holder 6, the inner surface of the side wall portion 6a of the outer holder 6 and the pellicle film 14 come into contact with each other, and the pellicle film 14 is scratched or the pellicle film 14 is damaged. 14 may be torn.

When the pellicle film is damaged or the pellicle film is broken in this way, when the photomask is used, the damage or the break of the pellicle film is transferred onto the wafer, resulting in a pattern defect. To prevent this, it is necessary to replace the relatively expensive pellicle,
This increases man-hours and costs, which is a cost disadvantage. Further, as described above, unless the pellicle is used, the dust adheres to the pattern surface of the photomask and is transferred onto the wafer.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a photomask pellicle in which the pellicle film is less likely to be damaged and a photomask capable of preventing dust from adhering to a pattern surface. And

[0010]

In order to achieve the above object, the present invention provides, as a first invention, a ring-shaped pellicle frame and a pellicle film attached to the pellicle frame so as to cover the opening on the front end side. In a pellicle for a photomask having a base end portion of a pellicle frame attached on a photomask, a projection portion is provided along an outer peripheral portion of the pellicle film, the projection portion projecting ahead of the pellicle film. A pellicle for a photomask is provided (claim 1).

Further, according to a second aspect of the present invention, a pattern is formed on one surface of the transparent substrate, and a transparent protective plate is fixed on the one surface of the transparent substrate so as to cover the pattern. A featured photomask is provided (claim 2). The photomask in the first invention and the second invention is a concept including a photomask and a reticle.

In the first invention, as the means for forming the protrusion, for example, as shown in an embodiment described later, a protective cover is attached on the photomask outside the pellicle frame, and the upper portion of the protective cover is attached to the protrusion. And a means for changing the shape of the pellicle frame to form a protrusion on a part of the pellicle frame, a means for attaching a cushion material on the pellicle frame through the pellicle film, and using this cushion material as the protrusion. However, the present invention is not limited to these.

In the first invention, the protrusion length of the protrusion from the surface of the pellicle film can be arbitrarily determined, but usually 1 to 5
It is suitable to set it to about mm. Further, the protruding portion may be provided continuously along the outer peripheral portion of the pellicle film or may be provided intermittently.

In the second invention, the material and shape of the transparent protective plate are not particularly limited, but the same material as the transparent substrate, such as quartz glass, can be used as the material. The shape may be similar to that of the transparent substrate, for example. The transparent protective plate can be fixed to the transparent substrate by any means such as an adhesive.

[0015]

In the pellicle according to the first aspect of the present invention, since the protruding portion is provided along the outer peripheral portion of the pellicle film so as to project ahead of the pellicle film, an object that damages the pellicle film, for example, the side wall of the inner holder described above. Contacts the protrusion and is less likely to contact the pellicle membrane. Therefore, the pellicle film is protected by the protrusion, and the pellicle film is less likely to be damaged.

In the photomask of the second invention, since the transparent protective plate is fixed to the pattern surface of the transparent substrate, dust adheres to the surface of the transparent protective plate and does not adhere to the pattern surface.

[0017]

EXAMPLES The present invention will now be specifically described with reference to examples, but the present invention is not limited to the following examples. 1 to 3 are sectional views showing an embodiment of a pellicle according to the first invention.

The pellicle 50 shown in FIG. 1 has a short-axis cylindrical ring-shaped pellicle frame 52 adhered to a photomask 58 with an adhesive 56, and a pellicle arranged so as to cover the front end side opening of the pellicle frame 52. The film 54 and the pellicle frame 52 are higher in height than the pellicle frame 52, and a ring-shaped protective cover 60 having a short-axis cylindrical shape is adhered to the outside of the pellicle frame 52 on the photomask 58 by an adhesive 62. In the pellicle 50 of this embodiment, the upper portion of the protective cover 60 is formed in the protruding portion A that protrudes ahead of the pellicle film 54. The protective cover 60 is preferably made of a material that does not easily generate dust, for example, a metal such as aluminum.

The pellicle 51 shown in FIG. 2 has a low step portion 6 inside.
4. A ring-shaped pellicle frame 52 having a short axis and a substantially cylindrical shape, which has a high step portion 66 on the outer side and is adhered to a photomask 58 by an adhesive 56, and a low step portion which covers the tip side opening of the pellicle frame 52. Pellicle film 54 disposed on the portion 64
Consists of In the pellicle 51 of this embodiment, the high step portion 66
Of the protrusion A in which the upper part of the protrusion protrudes beyond the pellicle film 54
Is formed.

A pellicle 53 shown in FIG. 3 is a ring-shaped pellicle frame 52 having a cylindrical shape of a short axis adhered to a photomask 58 with an adhesive 56, and a pellicle arranged so as to cover an opening on the front end side of the pellicle frame 52. The film 54 and a ring-shaped cushion member 68 mounted on the pellicle frame 52 via the pellicle film 54. In the pellicle 53 of this embodiment, the cushion material 68 is the pellicle film 5.
It is formed on the protruding portion A that protrudes further than 4. The cushion material 68 can be formed of a butyl rubber material or the like. The cushion material 68 can be attached by adhesion or the like.

FIG. 4 is a sectional view showing an embodiment of the photomask of the second invention. The photomask 70 of this example has a chrome pattern 74 formed on one surface of a transparent substrate 72 made of quartz glass, and a transparent protective plate made of quartz glass covering the chrome pattern 74 on one surface of the transparent substrate 72. 76 is fixed. In the photomask of this example, the transparent substrate 72 on which the chrome pattern 74 is formed is a conventional photomask. Therefore, the photomask 70 of this example is a photomask having a triple structure rather than a conventional double structure. is there. A concave portion 78 is formed on the surface of the protective plate 76 fixed to the substrate 72, and the chromium pattern 74 is arranged in the concave portion 78.

[0022]

According to the pellicle for a photomask of the first aspect of the present invention, the occurrence rate of damage to the pellicle film can be reduced. Therefore, by using the pellicle of the first invention, it is possible to reduce the occurrence rate of pattern defects in the semiconductor device due to damage to the pellicle film, reduce the work of replacing the pellicle film, and improve yield and man-hours. You can

According to the photomask of the second invention, it is possible to prevent dust from adhering to the pattern surface, and to reduce the incidence of pattern defects in the semiconductor device due to the dust adhering to the pattern surface. it can.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a pellicle according to the first invention.

FIG. 2 is a sectional view showing an embodiment of a pellicle according to the first invention.

FIG. 3 is a sectional view showing an embodiment of a pellicle according to the first invention.

FIG. 4 is a sectional view showing an embodiment of a pellicle according to the second invention.

FIG. 5 is a perspective view showing an example of a mask holder of the projection exposure apparatus.

6 is an enlarged cross-sectional view of the mask holder of FIG.

FIG. 7 is an explanatory diagram showing a case where exposure is performed using a photomask to which a pellicle is not attached.

FIG. 8 is an explanatory diagram showing a case where exposure is performed using a photomask to which a pellicle is attached.

[Explanation of symbols]

 A Projection 50 Pellicle 51 Pellicle 52 Pellicle Frame 53 Pellicle 54 Pellicle Film 58 Photomask 60 Protective Cover 64 Low Step 66 High Step 68 Cushion 70 Photo Mask 72 Transparent Substrate 74 Chrome Pattern 76 Transparent Protective Plate

Claims (2)

[Claims] 1. A ring-shaped pellicle frame, and a pellicle film attached to the pellicle frame so as to cover an opening on the front end side thereof. The base end of the pellicle frame is attached to a photomask for use. In the photomask pellicle according to the present invention, there is provided a protrusion that protrudes ahead of the pellicle film along the outer periphery of the pellicle film. 2. A photomask, wherein a pattern is formed on one surface of the transparent substrate, and a transparent protective plate is fixed on the one surface of the transparent substrate so as to cover the pattern.