JPH01111346A - Wafer for inspection use and its manufacture - Google Patents

Abstract

PURPOSE:To achieve a low cost without being damaged by a dry etching operation by a method wherein a transparent etching-proof film is formed on the main surface of a glass substrate and a light-shielding film pattern is formed on it. CONSTITUTION:A transparent silicon oxide film 2 of a uniform thickness is formed on the whole main surface of a glass substrate 1; a light-shielding film 3 is formed on its whole surface; a positive resist film 4 is coated on its whole surface. Then, a device pattern of an object to be inspected is reduction- projected on the positive resist film 4 by using a reticle of the object to be inspected, and is exposed to light; the film is developed; a resist of an exposed part is removed; the substratum light-shielding film 3 is exposed; the light- shielding film 3 is dry-etched by making use of a remaining positive resist film 4A as a mask; a light-shielding film pattern 3A is formed. Accordingly, because the surface of the glass substrate 7 is not damaged directly by a dry- etching operation, the same glass substrate 1 can be reused many times only if the transparent film 2 is removed and is formed again. By this setup, a low cost is achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a technique for inspecting a reticle.

[Conventional technology]

The production of IC (integrated circuits) requires 10 to 20 photoetching steps, and the same number of steps requires a mask or reticle (hereinafter referred to as a reticle) that is free from defects and foreign matter. If foreign matter adheres to the reticle when setting such a reticle in the aligner, a large number of defective ICs will be generated, so it is necessary to perform a test exposure with the reticle placed in the aligner. .

Therefore, the present inventor investigated a technique for calibrating a reticle on which a device pattern is formed while it is set in an aligner. The following is not a publicly known technology, but
This is a technique studied by the present inventor, and its outline is as follows.

First, a light-shielding metal film is applied to the whole surface of the glass substrate wafer.
For example, an aluminum film is formed, and then a resist is applied on top of it. Next, using a reticle set on the aligner that is the object to be examined, the device pattern formed on the surface of the object is projected onto the resist and exposed. Note that a plurality of identical device patterns, such as two or four, are formed on this reticle. Next, the resist is developed, and the underlying metal film is etched with an alkaline etching solution using the remaining resist as a mask to produce a wafer for inspection. and comparing the two selected same device patterns in the inspection wafer with each other,
The test subject is inspected to see if there is any foreign matter attached to it. After inspection, the light-shielding film is removed with a liquid that does not affect the glass substrate and reused.

However, although it was able to handle the inspection of glass masks with relatively large light-shielding film pattern widths, it was difficult to inspect them with the current layout. When the fM width becomes narrower to 1 to 2 μm or even submicrons, in isotropic etching such as wet etching, etching progresses evenly in both the vertical and horizontal directions from the etched portion of the resist. Due to the undercut condition,
The pattern shape of the inspection wafer itself becomes trapezoidal, making it unsuitable for use. Therefore, when we tried using dry etching (for example, plasma etching) that exhibits anisotropic etching characteristics instead of wet etching, the etching shape of the pattern was very good, but the underlying glass substrate was severely damaged and the translucency There is a problem in that the glass substrate is lost and cannot be used repeatedly, and the expensive glass substrate must be replaced periodically, resulting in high costs.

An object of the present invention is to provide a technique for producing test wafers at low cost without causing damage due to dry etching.

Another object of the present invention is to provide a technique for improving the inspection accuracy of a glass mask on which a fine pattern is formed.

The above and other objects and novel features of the present invention will become clear from the description of this specification and the drawings of the foil material.

[Failure to solve the problem]

A brief overview of typical inventions disclosed in this application is as follows.

That is, a transparent etching-resistant film is formed on the main surface of a glass substrate, and then a light-shielding film pattern is formed.

[Effect]

According to the above-mentioned means, the glass substrate can be reused simply by removing the etching-resistant film, so that inspection wafers can be produced at low cost and with high pattern accuracy.

〔Example〕

FIG. 1 is a cross-sectional view of a test wafer according to an embodiment of the present invention, FIGS. 2A to 2D are manufacturing process diagrams of the calibration wafer shown in FIG. 1, and FIG. 3 is an explanatory diagram of the test method.

Hereinafter, a detailed explanation will be given based on the above drawings. In FIG. 1, 1 is a glass substrate made of a transparent material such as quartz glass, and its main surface is flat. A transparent film 2 is formed on the main surface of the glass substrate 1, and is, for example, a silicon oxide film, which is formed by chemical vapor deposition (CVD), sputtering, or the like. 3A is a light shielding film made of aluminum, chrome na, etc., and is formed by patterning in a resist process. Next, a method of manufacturing this inspection wafer W will be explained. First, a transparent silicon oxide film 2 is coated on the main surface of a glass substrate 1 made of quartz glass.
Formed with a uniform thickness over the entire surface using the VD method (Figure 2A)
. Next, a light-shielding film 3 made of aluminum (A) or the like is formed over the entire surface of the silicon-acid arsenic film 2 by vapor deposition or sputtering (FIG. 2B). Furthermore, a positive resist film 4 is applied over the entire surface (FIG. 2C). Next, using a reticle (not shown) of the object to be examined (set in an aligner), the device pattern of the object to be examined is reduced and projected onto the body registration m4 and exposed.

Next, the positive resist film 4 is developed, and the resist in the original contact area is removed to expose the underlying light shielding film 3. Then, using the remaining positive resist film as a mask, the light shielding film 3
is etched using a dry etching technique to form a light shielding film pattern 3A.

At this time, the exposed surface of the silicon oxide film 2 is damaged by the dry etching and becomes a slightly rough surface, but a new silicon oxide film 2 is formed each time it is inspected or every time transparency is lost. Therefore, damage to the silicon oxide film 2 has no effect at all. next,
The positive resist film 4A is removed to obtain a calibration wafer 4.

Using this inspection wafer 4, the pattern of the reticle to be inspected is inspected, for example, in the following manner. First, from the light source 5 below the inspection wafer 4, the reflection mirror 6a is
, 6b, select two identical device patterns and irradiate them with light. The source of the irradiation on the device butter 77a is the light-shielding film putter, and the part where the 73 people are formed is shielded from light.
The portion formed by the glass substrate 1 and the silicon oxide film 2 is transparent as is. The image is magnified by a lens 8aK, reflected by reflection mirrors 6c and 6d, and further passes through a half mirror 9 to reach a magnification adjustment lens 10, where it is adjusted so that the composite image can be clearly seen. - On the other hand, the light irradiated onto the device pattern 7b is blocked not only by the pattern of the light blocking film 3A but also by the portion to which the foreign matter 11 is attached. Therefore, the image of the foreign object 11 is also reflected by the lens 8b and the reflecting mirror 6.
e, it reaches the observer's eye 11 through an optical system including a nof mirror 9 and a magnification adjustment lens 10. At this time, portions without defects overlap, and foreign matter or defective portions do not overlap.

In this way, the presence or absence of foreign matter or defects is inspected, and if there are no foreign matter or defects, this means that there are no foreign matter or defects in the object reticle set on the stepper, and the main exposure is performed. If a foreign object or defect is found on the inspection wafer W, this means that there is a foreign object or defect in the reticle of the test object, so the wafer W is removed from the stepper and the reticle is replaced or repaired.

After the calibration is completed, the light-shielding film pattern 3A of the test sea urchin/%W is removed, and then the silicon oxide film 2, which has lost its transparency with hydrofluoric acid, etc., is removed so that it can be reused in the next calibration. .

Next, the functions and effects of this embodiment will be explained.

(1) By forming a transparent film on a glass substrate and forming a light-shielding film on top of it, even if the light-shielding film is patterned by dry etching, damage will not directly hit the glass substrate surface, so the transparent film can be removed. However, it is possible to reuse the same glass substrate many times just by re-forming it.

(Since there is no need to replace the expensive glass substrate (especially quartz glass) every time dry etching is performed from 21(1)K, it is possible to significantly reduce costs and improve the accuracy of testing objects with fine patterns. The effect of being able to perform well is obtained.

(3) By using a silicon oxide film as the transparent film, since it is inexpensive and its manufacturing method is used in semiconductor manufacturing, it is easy to form and can be formed with a uniform thickness.

Although the invention made by the present inventor has been specifically described above based on examples, it goes without saying that the present invention is not limited to the above-mentioned examples, and can be modified in various ways without departing from the gist thereof. Nor. For example, in this example, a silicon oxide film is formed on the surface of the glass substrate, but a transparent non-material such as PSG (polysilicate glass) is used.
It may also be a transparent organic tape.

In the above explanation, the invention made by the present inventor was mainly applied to inspection wafers, which is the background field of application, but the invention is not limited to this. It can be applied to all masks and reticles on which patterns are formed. In this case, the effect that the pattern of the mask or reticle itself can be formed extremely finely and with good pattern shape can also be obtained.

〔Effect of the invention〕

A brief explanation of the effects obtained by representative invention K among the inventions disclosed in this application is as follows.

In other words, the light shielding film formed on the surface of the glass substrate can be removed without damaging the surface of the glass substrate.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a test wafer according to an embodiment of the present invention. FIGS. 2A to 2D are manufacturing process diagrams for the test wafer shown in FIG. 1. FIG. FIG. 3 is an explanatory diagram of an inspection method using a wafer. 1...Glass base plate, 2...Silicon oxide film, 3...
・Light shielding film, 4...Positive resist, 5...Light source, 6.
・Reflection mirror, 7... Techheis pattern, 8...
Lens, 9... Half mirror 110... Adjustment lens, 11... Observer. Agent 9'P Burial Officer Katsuo Ogawa ゛□11, No. 1
IS-q- to Figure 2A Figure 25h

Claims (1)

[Claims] 1. A glass substrate, a transparent film formed on its main surface,
An inspection wafer having a light-shielding film exposed and patterned using a mask or a reticle, which is an object to be inspected, on the transparent film. 2. The inspection wafer according to claim 1, wherein the transparent film is a silicon oxide film. 3. A step of preparing a flat glass substrate and forming a transparent film on the top thereof, a step of forming a light-shielding film on the transparent film, a step of applying a resist on the light-shielding film, and a pattern of the object to be examined. a step of projecting and exposing the resist onto the resist, a step of developing the resist, and a step of patterning the underlying light-shielding film using the resist remaining after development as a mask;
A method for manufacturing a wafer for inspection, which includes a step of removing remaining resist and exposing a light-shielding film pattern.