JPH01173717A - Blank plate - Google Patents

Abstract

PURPOSE:To prevent the electrification of a blank plate when an electron beam exposing operation is conducted, and also to prevent the exasperation of a light-shielding film by a method wherein at least an exposed part of conductive a light-shielding film is provided on the circumferential part of a transparent substrate, and a conductive light-shielding film is formed on the region other than the circumferential part of a substrate excluding said exposed part. CONSTITUTION:A transparent substrate 2 is supported by a holder 13 having a shielding plate 20. The substrate 2 is supported by the four corners of the holder 13, and a plurality of notched parts 16 are formed on the shielding plate 20. The substrate 2 is provided in a vacuum chamber opposing to the source of evaporation of a target 12, the circumferential part of the substrate 2 is shielded from the source of evaporation or the target 12, and a light-shielding film is formed using a vapor-deposition method or a sputtering method. As the exposed part 22 of a metal thin film 3, having low electric resistance, is formed on the surface of the transparent substrate 2 of a blank plate 1, the projected electrons pass through a resist layer 5 when an electron exposing operation is conducted, and after the electrons have reached the layer of large electric resistance on the surface layer 4, they can be shifted easily from the lower layer of metal thin film 3 having low electric resistance to a conducting pin 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a blank plate for a photomask used in semiconductor manufacturing and the like.

[Conventional technology]

Blank plate for photomask used in semiconductor manufacturing etc.
As shown in FIG. 5, a light-shielding film 3 is formed on a transparent substrate 2 such as glass, and an anti-reflection film 4 is further formed on top of the light-shielding film 3, as shown in FIG. Anti-reflection film 4
Those forming a, 4b are known.

By the way, when manufacturing a photomask, the process of forming a pattern on a resist on a blank plate may use a light exposure device or an electron beam exposure device.
Among them, the blank plate l used in electron beam exposure equipment is
The light-shielding film 3 is made of a conductive material with a small electric resistance value, and is a material that blocks the photosensitive wavelength range of the photosensitive resin, for example, CrNTa, S1%.
A metal material such as W-, Mo, CrSi, TaSi, MoSi, etc. is used, and an insulating oxide film or nitride film is used as the anti-reflection film 4 to provide a surface anti-reflection function.

FIG. 7 shows a process of forming a resist pattern on a blank plate using an electron beam exposure device. A cyst layer 5 is formed on the surface layer 4 of the blank plate 1, and the resist layer 5 is exposed to an electron beam.

At this time, the electrons that have reached the resist layer 5 pass through the resist layer 5 and reach the surface layer 4 of the blank board 1 while exposing the resist. If these electrons are charged directly on the blank plate, they will cause a potential drop and will also block the arrival of subsequent incident electrons, leading to a decrease in the amount of exposure to the resist film and destabilization, causing formation on the resist film. Uneven exposure occurs in the pattern, making it difficult to form highly accurate fine patterns. Therefore, even in the photomask finally obtained by developing such a resist film and etching the blank plate 1, it is difficult to form a fine pattern with high precision.

To prevent this problem, conventional electron beam exposure equipment
By grounding the conductive pin 6 to the surface layer 4 of the blank board 1, conduction is established and the blank board 1 is prevented from being charged.

On the other hand, in conventional blank plates, the light-shielding film 3 is formed by vapor deposition, sputtering, etc., so that the light-shielding film 3 is formed even on the peripheral portion 7 of the transparent substrate 2, as shown in FIG. Since the periphery of the transparent substrate 2 is chamfered, minute micro-cranks are present on the periphery 7, the chamfered surface 8, and the end surface 9. Then, the peripheral portion 7 of the transparent substrate 2
, the light-shielding film 3 on the chamfered surface 8 and the end face 9 has a weak adhesion force to the transparent substrate 2 compared to the light-shielding film on the central part of the transparent substrate 2, and is difficult to adhere to during the photomask production process. During use, it has the disadvantage that it may peel off as fine particles and adhere to the pattern section 10 of the photomask, causing defects or causing t1 damage to the pattern section 10.

In order to eliminate this drawback, Japanese Utility Model Application Publication No. 60-39047 proposes forming a light-shielding film on the transparent substrate except for the peripheral area. To explain this with reference to FIGS. 9 and 10, a transparent substrate 2 placed facing an evaporation source or target 7) 12 in a vacuum chamber is
It is held in a holder 13 that shields its peripheral part from the evaporation source or target 12, and in this state, a light-shielding film material is flung onto the transparent substrate 2 by vapor deposition or sputtering, as shown in Fig. 1θ. , the light-shielding film 3 is formed on the transparent substrate 2 except for the peripheral portion 15.

[Problem that the invention seeks to solve]

However, in the process of forming a resist pattern on a blank plate using the conventional electron beam exposure apparatus explained in FIG. During exposure, electrons that reach the surface of the substrate cannot move through the surface layer 4 and cannot reach the conductive pins 6, and at the same time, the light-shielding layer in the lower layer that allows electrons to freely move from the surface layer 4 Even if it moves to the conductive film 3, the surface layer 4 becomes a barrier and it cannot reach the conductive pin 6, which is a problem.

As a result, conventional conduction methods cannot prevent a hard mask substrate with such a configuration from being charged during electron beam exposure.Furthermore, in order to ground the conductive pins 6 to the surface of the blank board, the resist layer 5 is It also has the problem of causing damage.

Conventionally, as a means to solve this problem, an improved substrate in which the electrical resistance of the surface layer 4 is reduced has been devised, but this impairs the function of preventing surface reflection, which is the original purpose of the substrate.

In reality, the reflectance of a low-reflection substrate is usually 10 at 436 nm.
%, whereas the improved substrate has a reflectance of 436n.
The reflectance increases to around 30% at m. Therefore, such methods have not essentially solved the problems of the prior art.

In addition, in the conventional hard mask substrate illustrated in FIGS. 9 and 10, the surface layer acts as a barrier and cannot prevent charging during electron beam exposure, as described above. There is a problem in that the portion 15 may be newly charged.

The present invention solves the various problems mentioned above. It prevents charging of a blank board during electron beam exposure, and also solves the problem of peeling of the light-shielding film on the peripheral part, chamfered part, and end face of the blank board. The purpose is to solve this problem and provide a photomask with a fine pattern with high precision.

[Means for solving problems]

To this end, the blank plate of the present invention is a blank in which a conductive light-shielding film and an anti-reflection film are formed on one side of a transparent substrate, and at least one exposed portion of the conductive light-shielding film is provided around the transparent substrate. The present invention is characterized in that the conductive light-shielding film is formed in areas other than the peripheral area of the transparent substrate excluding exposed areas.

(Function) In the present invention, as shown in FIG. 2, for example, in the process of patterning a blank plate using an electronic exposure device, the underlying metal thin film 3 with low electrical resistance is exposed on the surface of the transparent substrate 2 of the blank plate 1. Because the portion 22 is formed, the irradiated electrons transmit through the resist layer 5 during electron exposure, and after reaching the layer with high electrical resistance of the surface layer 4, instantly
The conductive pin 6 is connected from the lower metal thin film 3 with lower electrical resistance.
It is easily movable.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. Note that the layer structure of the blank board itself is the same as that shown in FIGS. 7 and 8, so a description thereof will be omitted.

First, the method for manufacturing a blank board of the present invention will be explained with reference to FIGS. 3 and 4.

In FIG. 3, the transparent substrate 2 is supported by a holder 13 having a shielding part 20. As shown in FIG. The support is usually a holder 13
It is supported at the four corners of. Further, as shown in FIG. 4, a plurality of notches 16 are formed in the shielding plate 20. As shown in FIG. The transparent substrate 2 is placed in a vacuum chamber facing the evaporation source or target 12, and the periphery of the transparent substrate 2 is shielded from the evaporation source or target 12, and a light-shielding film is applied by vapor deposition or sputtering. Form a film.

FIG. 1 shows a blank 1 produced by the method described above. On the surface of the transparent substrate 2 of the blank plate 1, an exposed portion 22 of the underlying metal thin film 3 with low electrical resistance is formed, so that during electron exposure, the irradiated electrons are transferred to the resist, as shown in FIG. After passing through the layer 5 and reaching the surface layer 4, which has a high electrical resistance, it is structured so that it can be easily moved from the lower layer metal thin film 3, which has a lower electrical resistance, to the four pins 6 instantly.

Note that the present invention is not limited to the above-mentioned embodiments, and various modifications are possible.For example, in the above-mentioned embodiments, the exposed portions 22 are formed at three locations, but the present invention is not limited to this. Instead, it may be at one or more locations.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to prevent the blank board from being charged with electron vAn light, and also to solve the problem of peeling of the light-shielding film on the peripheral part, chamfered part, and end face of the blank board, and to achieve high precision. A photomask with a fine pattern can be provided. That is, by grounding a conductive pin to the end of the exposed portion formed around the transparent substrate to prevent charging, it is possible to easily prevent the blank board from being charged.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a blank temporary embodiment of the present invention;
FIG. 2 is a diagram for explaining the action of the blank plate of the present invention during electronic exposure, FIGS. 3 and 4 are diagrams for explaining the method for manufacturing the blank plate of the present invention, and FIG. cross section,
Figure 4 is a bottom view of Figure 3, Figures 5 and 6 are cross-sectional views showing the general configuration of a blank plate, and Figure 7 explains electronic exposure using a conventional blank plate. diagram for,
FIG. 8 is a diagram for explaining problems with conventional blank plates, and FIGS. 9 and 10 are diagrams for explaining conventional blank plates. DESCRIPTION OF SYMBOLS 1... Blank board, 2... Transparent substrate, 3... Conductive light shielding film, 4... Antireflection film, 5... Resist, 6
... Conductive pin, 13... Holder, 16... Notch, 20... Shielding part, 22... Exposed part. Applicant Dai Nippon Printing Co., Ltd. Representative Patent Attorney Hiroki Shirai (3 others) Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 figure

Claims (1)

[Claims] (1) In a blank plate in which a conductive light-shielding film and an anti-reflection film are formed on one side of a transparent substrate, at least one exposed portion of the conductive light-shielding film is provided around the transparent substrate, and the transparent substrate excluding the exposed portion is provided. A blank board characterized in that the conductive light-shielding film is formed in areas other than the peripheral area.