JPS6381351A - Photomask - Google Patents

Abstract

PURPOSE:To improve a yield in manufacture of a photomask, by forming a transfer pattern film so that no acute part is formed on a photomask substrate. CONSTITUTION:Transfer patterns 11 and 12 neighboring on a wiring forming pattern 10 are formed on a glass substrate 1 as the photomask substrate in a shape that a corner whose tip is acute, is eliminated and rounded. Since a part where electric charge is concentrated on the transcribing patterns 11 and 12 is eliminated, even when the electric charge is generated by abrasion, etc., the transfer patterns 11 and 12 are hard and reluctant to the damage due to electrostatic destruction at the time of performing the appearance inspection of the photomask, even when a worker touches the photomask. In this way, the yield in the manufacture of the photomask can be improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to semiconductor manufacturing technology and a technology that is particularly effective when applied to the formation of transfer patterns on photomasks. Concerning techniques that can be used effectively.

[Prior Art] As a method for manufacturing a photomask, for example, high-purity chromium is vacuum-deposited under oxygen partial pressure on a glass substrate heated to an appropriate temperature. A known method is to form a pattern (pattern) and then perform processes such as applying a photomask, exposing, developing, and etching.
(See page 311 of the "Semiconductor Handbook" published on March 30th).

[Problems to be Solved by the Invention] 'The transfer pattern (chromium oxide film) formed on the glass substrate by the above-described photomask manufacturing method has edges such as corners A to C, as shown in FIG. It has a pointed part. in general.

Electric charges tend to accumulate in the sharp parts like this.

Therefore, if a transfer pattern is formed on a glass substrate with a sharp tip, an operator may touch the photomask when performing an appearance inspection to evaluate the quality of the photomask. When.

There was a problem in that electrostatic damage occurred between the transfer patterns 30 and 32 and between the transfer patterns 31 and 32 due to the charged corner A-C of the transfer pattern, resulting in damage to the transfer pattern.

Furthermore, in order to remove foreign matter adhering to the surface of the photomask, for example, when the surface of the photomask is cleaned with ultrapure water, which has no electrical conductivity, the photomask becomes electrically charged, and the charges are concentrated at corners A to C, forming a pattern for transfer. There was a problem that the battery was destroyed by electrostatic discharge. Especially with issues like this.

This occurred frequently in long parts of the transfer pattern and patterns in the vicinity.

Furthermore, when a photomask manufactured by the above method is used to transfer a pattern having a sharp tip to a wafer, similar to the transfer pattern, the pattern may be transferred onto the wafer due to various factors that occur during the wafer manufacturing process. There has been a problem in that the pattern is charged and electrostatic damage occurs, resulting in damage to the pattern.

Forming a transfer pattern having a sharp corner in this way causes the above-mentioned problems and lowers the yield of photomask manufacturing.

Furthermore, the yield of the wafer manufacturing process is also reduced.

An object of the present invention is to improve the yield of photomask manufacturing.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Means for Solving the Problems] Representative inventions disclosed in this application will be summarized as follows.

That is, a transfer pattern is formed on the photomask substrate by removing the sharp end portion and having a rounded shape.

[Function] According to the above-described means, there is no part where charges are concentrated in the mask pattern formed on the mask substrate, and charges are uniformly distributed in the transfer pattern, thereby preventing electrostatic damage. The above object of improving the yield of photomask manufacturing can be achieved.

[Example 1] FIG. 1 shows an example of the shape of a transfer pattern formed on a glass substrate 1 as a photomask substrate when the present invention is applied.

In the figure, 10 to 12 are transfer patterns.

Among these, the transfer pattern 10 is for forming, for example, an aluminum layer as a ground line on a semiconductor chip by transfer.

The transfer patterns 11 and 12 are for forming, for example, an aluminum layer that will become an electrode of a semiconductor element formed on the chip surface. The distance a between the transfer patterns 10 and 12 and the distance between the transfer patterns 11 and 12 are each narrow, about 4 μm.

In this embodiment, the patterns 11 and 12 adjacent to the wiring forming pattern 10 are formed into rounded shapes with sharp corners removed, as shown in the figure.

In the conventional transfer patterns 31 and 32 shown in Fig. 3, the corners A to C are shaped into sharp corners, and charges tend to accumulate there.If they are shaped like this, electrostatic damage is likely to occur. However, in the above example, pattern 11
The rounded corners at 12° prevent electrical charge from accumulating. In particular, as in the above embodiment, a transfer pattern for forming an elongated pattern such as a wiring layer on a chip has a large amount of charge as a whole, so there is a risk of damage between the transfer pattern and other transfer patterns in the vicinity. Discharge occurs and electrostatic damage is likely to occur, but if the corners of one of the transfer patterns are rounded, charge concentration is less likely to occur and electrostatic damage is prevented.

FIG. 2(A) shows that high-purity chromium is vacuum-deposited on a glass substrate 20 under an oxygen partial pressure.
A chromium oxide film 21 as a light-shielding thin film is formed on the surface of 0, and a photoresist 22 is applied.

The drawing of the transfer pattern is not particularly limited, but is performed by an electron beam drawing device. In this embodiment, the transfer patterns 11 and 12 need to have the shape as shown in FIG. The design data for the formation is computer-aided (CAD).
ign) system, transfer pattern 11.1
2 is drawn, and then subjected to development processing, etching processing, etc., to form the state shown in FIG. 2(B).

The chromium oxide film 21 formed on the glass substrate 20 has a transfer pattern 11.1 in FIG. 1 based on the design data.
It is made so that it does not have sharp corners like 2.

In the above embodiment, the sharp edges of the transfer pattern are removed on the photomask substrate to form a rounded transfer pattern, so even if electric charges are generated due to friction, etc., the transfer pattern will Because there are no areas where electric charges are concentrated, even if an operator touches the photomask during visual inspection to evaluate the quality of the photomask, the transfer pattern will not be damaged by electrostatic damage. This has the effect of making it more difficult.

Furthermore, in the above embodiment, by removing the sharp edges on the photomask substrate and forming a rounded transfer pattern, there is no part where electric charge is concentrated on the transfer pattern. As a result, even if the photomask surface is cleaned with ultrapure water or the like to remove foreign matter adhering to the photomask surface, the transfer pattern is less likely to be damaged by electrostatic damage.

Furthermore, in the above embodiment, the sharp end portions are removed and a rounded transfer pattern is formed on the photomask substrate, so that the photomask manufactured according to this embodiment in the wafer exposure process By using this method, a pattern is formed on the wafer that takes into account the prevention of charging based on the transfer pattern.

This has the effect that patterns formed on the wafer are also less likely to be damaged by electrostatic discharge damage.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the above Examples and can be modified in various ways without departing from the gist thereof. Nor.

For example, in the above embodiment, the photomask drawing is performed by an electron beam drawing device, but it may be performed by a light exposure device.

In the above explanation, the invention made by the present inventor was mainly applied to photomask formation technology, which is the background and field of application, but the invention is not limited to this, and includes patterning design of printed circuit boards, etc. Applicable to

[Effects of the Invention] The effects obtained by typical inventions disclosed in this application are briefly explained below.

In other words, since the transfer pattern is formed on the photomask substrate by removing the sharp tip and having a rounded shape, it becomes difficult for electric charge to concentrate locally on the transfer pattern. The transfer pattern is less likely to be destroyed by electrostatic damage, and the yield of photomask manufacturing is improved.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a photomask designed to prevent electrification from forming on a mask substrate. FIG. 2(A) is a sectional view showing the state of the mask substrate in FIG. 1 before pattern formation, and FIG. 2(B) is a sectional view showing the state of the mask substrate in FIG. 1 after pattern formation. , FIG. 3 is a plan view showing the shape of a transfer pattern in a conventional photomask. 10-12.30-32...Transfer pattern. 20...Glass substrate, 21...Chromium oxide film,
22...Photoresist. Figure 1 (A) Figure 3

Claims (1)

[Scope of Claims] 1. A photomask in which a film constituting a transfer pattern is bonded to one surface of a plate-shaped photomask substrate, the transfer pattern having no sharp edges on the photomask substrate. A photomask characterized by a film formed thereon. 2. The above-mentioned transfer pattern coating is a pattern coating in which a small pattern having a sharp point is present in the vicinity of an elongated pattern for forming a semiconductor integrated circuit by photolithography. Photomask as described in section.