JPS6131610B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reticle inspection method, and more particularly to a reticle inspection method related to pattern printing on a wafer in the manufacture of semiconductor devices. The reticle here has a pattern that is 10 times the size of the chip used to print element (chip) patterns onto wafers (semiconductor substrates).

In pattern printing using the so-called step-and-repeat method, in which a plurality of chip patterns are exposed directly onto a semiconductor substrate such as silicon by using the reticle as a mask, if the reticle, which is the mask, is defective, all chips are defective. This results in a loss of labor and wafers. However, according to the prior art, the pattern of an exposed reticle is inspected by the inspector's eyes, which takes several hours.

The present invention solves the above problems experienced in the prior art. First, a reticle with a pattern 10 times the size of the chip pattern is formed. As is well known, the reticle is constructed by selectively forming a mask pattern such as chrome on a glass substrate. In the present invention, after confirming that the reticle is not defective, a chip pattern is created on a glass substrate by lens baking, and the printed pattern is visually inspected to confirm that it is not defective. Such a chip pattern will be referred to as a reference chip pattern because it will serve as a reference for subsequent tests. In the present invention, a reticle is inspected using such a reference chip pattern, and the method will be explained below with reference to the accompanying drawings.

First, a glass substrate 1 having approximately the same film thickness as the wafer shown in FIG. 1 is prepared, and one surface of the glass substrate 1 has chromium or a similar substance deposited thereon. Since this process can be performed according to conventionally known techniques, detailed explanation thereof will be omitted. The reason why the thickness of the glass substrate 1 is made to be approximately the same as that of the wafer is to improve operability by keeping the focus of the image projected from the reticle approximately constant.

Next, a positive type photoresist is applied onto the chromium film on the glass substrate 1 prepared in this manner. As such a photoresist, for example, commercially available AZ1350 manufactured by Shipley, Inc. in the United States can be applied. In this state, one row of chip patterns of the reticle are printed near one edge of the glass substrate 1 along the edge using the reticle. The inspector visually confirms that this pattern is not defective. Next, the chromium is etched using the photo resist as a mask, and the glass substrate is removed.
A row of reference chip patterns 2 . . . is formed on the top along one edge thereof. A glass substrate as described above on which chromium is vapor-deposited is prepared for each window opening pattern in the semiconductor device manufacturing process. Immediately before opening the window in the actual manufacturing process using the reticle as it is, the reticle to be inspected, that is, the glass substrate, is placed next to the row of reference chip patterns on the glass substrate as shown in FIG. The chip pattern 3 of the reticle, which has a chip pattern formed thereon and which is at the stage of being applied to the actual manufacturing process, is printed in one row, and this chip pattern and the reference chip pattern are comparatively inspected using an automatic inspection device. , the integrity of the reticle is inspected during use in the manufacturing process. When performing this inspection, it is important that the chip pattern is printed on the glass substrate and that it is transparent to light. The automatic inspection described above shines light on the reference chip pattern and the chip pattern to be inspected, converts it into an electrical signal, and cancels out the signal from the reference chip pattern and the signal from the chip pattern to be inspected. Combine to match. If the chip pattern reticle to be inspected is not defective, the combination of both signals will not output a separate signal, but if it is defective or has dust attached, it will generate one signal, and its Signals can be captured automatically.

According to the method of the present invention, automatic inspection is performed through the pattern ring image, chrome etching, and photoresist peeling, but the time required here is 10 to 20 minutes, which is different from the conventional method. The time required is reduced to about one-tenth that of visual inspection, and the reliability of the inspection can be significantly improved. Then, the reticle determined to be non-defective as a result of the comparative inspection is directly applied to the actual manufacturing process.

When the use of the reticle in the manufacturing process for one lot is completed, the chip pattern is printed onto the glass substrate again using the reticle in order to determine whether the reticle can be used in the next manufacturing lot. . This new chip pattern may be formed parallel to the chip pattern 3 used in the previous production lot 3' and inspected with reference to the reference chip pattern 2, or the chip pattern used in the previous production lot may be If No. 3 is not defective, it may be inspected in comparison with No. 3. In this way, the above-described testing process can be repeated until no further chip patterns to be tested can be printed onto the glass substrate.

[Brief explanation of the drawing]

Fig. 1 is a front view showing a state in which a reference chip pattern is printed on a glass substrate used in carrying out the method of the present invention, and Fig. 2 shows a state in which a chip pattern to be inspected is printed next to the reference chip pattern. 2 is a front view of the glass substrate shown in FIG. 1. FIG. 1... Glass substrate, 2... Reference chip pattern, 3, 3'... Chip pattern to be inspected. 〓〓〓〓

Claims (1)

[Claims] 1. A reference pattern is formed on a thin film on a substrate using a desired reticle, and before an exposure process using the reticle, the pattern of the reticle is formed in line with the reference pattern on the substrate, and the reference pattern is A reticle inspection method characterized by inspecting the reticle by comparing a pattern with a newly formed pattern.