JPH02106746A - Mask blank - Google Patents

Abstract

PURPOSE:To facilitate a theta adjustment and to shorten the time for adjustment by using regions on a glass substrate where a light shielding film is not formed as patterns for the rough theta adjustment of an inspection apparatus, etc. CONSTITUTION:A stage is moved to the position of a mask 5 and the center of a rectangle 1 on the left side is aligned to the center of the visual field of a microscope. The stage is then moved to the position of the mask 5 to bring the position right under the rectangle on the right side to the center of the visual field. A turn table is rotated by alpha to match the rectangle 2 with the height of h/2 if the center of rotation of the turn table exists at the center of the mask. The rough adjustment is thus completed. The patterns such as patterns 7 and 8 used for the fine theta adjustment having the same Y coordinate are regarded as the two same patterns and the fine adjustment is carried out by the similar method. The theta adjustment is thus easily carried out and the time required for the adjustment is shortened even if the patterns suitable for the theta adjustment do not exist.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a mask blank that is a material for a photo mask used in the manufacture of semi-quad integrated circuits.

(Prior art) Mask blanks, in which a light-shielding film such as chromium or molybdenum silicide is formed on a substrate such as quartz or low-expansion glass, have traditionally been used as materials for photomasks (hereinafter abbreviated as masks). . This light shielding film is formed over the entire surface of the substrate. A pattern is formed by removing the light-shielding film from areas other than predetermined portions of the mask blank. Before use, patterned masks and reticles are subjected to inspections such as appearance inspection, pattern defect inspection, element dimension inspection, and pattern overlay inspection, and only those that pass are used.

The above inspection is performed after attaching the normal mask to the mask holder.
It is carried out by being mounted on the moving stage of the inspection device. The stage can be moved in the X and Y directions, and the mask holder can be rotated on a rotary table. When performing the above inspection, first, the rotary table is rotated to adjust the inclination (hereinafter referred to as 0) so that the X-direction line of the mask pattern and the X-movement direction of the stage match.

Conventionally, the above-mentioned 0 adjustment was performed using a mask pattern as follows. For a mask with a scribe line or a long linear pattern in the X direction, first align the scribe line with the cross mark at the center of the field of view of the microscope. Next, the stage is moved to the right or left, and the rotation direction is determined based on the direction in which the pattern shifts, and the rotary table is rotated.

Move the stage to the right or left again and rotate the rotary table to adjust O. - While repeating the above operations, adjust θ until there is no pattern deviation, so that the line in the X direction of the mask pattern and the moving direction of the stage accurately match.

For masks that do not have a suitable pattern such as a scribe line, a Y coordinate is used instead of a scribe line, although the X coordinate is different.
Perform the same operation as in 1. using two patterns with the same coordinates.

(Problem to be Solved by the Invention) However, in conventional mask blanks, if there is a large deviation in the O direction when the mask is attached, after aligning one pattern with the center of the field of view of the microscope, the stage is moved to the other. Even if an attempt is made to move the pattern to the position of the other pattern, the other pattern will be out of the field of view of the microscope, making it difficult to search for the other pattern, resulting in the problem that zero adjustment takes time.

The present invention solves the above-mentioned conventional problems, and aims to provide a mask blank in which θ adjustment can be easily performed. .

(Means for Solving the Problems) In order to achieve the above object, the mask blank of the present invention includes a glass substrate with a plurality of regions in which no light shielding film is formed.

(Function) Therefore, in the mask reticle manufactured using the mask blank of the present invention, by using the area where the light shielding film is not formed as a pattern for O coarse adjustment, a mask pattern suitable for O adjustment can be obtained. Even if it does not exist, the time for zero adjustment can be shortened and the same area can be used as a 1'' scale for the position coordinates in the dry plate.

(Example) FIG. 1 is a plan view of a mask blank according to an example of the present invention. In Fig. 1, 1 to 4 are areas located at the center of each side where no light shielding film is formed, and each is a pattern consisting of a rectangle with a long side length a and a short side length b. be. FIG. 2 is a diagram showing a method of coarse O adjustment in the above embodiment, and FIG. 3 is a diagram showing a method of fine adjustment of θ. In Figure 2, 1 to 4 are 1 in Figure 1.
4 to 4, and 5 and 6 are mask positions at the time of O rough adjustment. Further, 7 and 8 in FIG. 3 are patterns used for O fine adjustment.

Next, methods for coarse and fine adjustment of θ will be described for a mask manufactured using a mask blank having the pattern shown in FIG. In FIG. 2, the stage is first moved to the position of the mask 5, and the center of the rectangle 1 on the left side is aligned with the center of the visual field of the microscope. This position can be easily found because it is in the center of the left side of the mask plate. Next, move the stage in the X direction to the position of the mask 6 to bring the area directly below the rectangle on the right side to the center of the field of view. This position can be easily found because it is at the right edge of the mask plate. At this time, the rectangle 2 is at a height h from the center of the field of view.

Here, when the rotation center of the rotary table is at the center of the mask, the coarse adjustment is completed by rotating the rotary table by α and making the rectangle 2 match the height of h/2. Further, when the rotation center of the rotary table is at the center of the left side (the position of rectangle 1), the rough adjustment is completed by rotating the rotary table by α once and aligning it with the center of the field of view of rectangle 2. After that, in FIG. 3, patterns with the same Y coordinate such as patterns 7 and 8 used for θ fine adjustment are regarded as the two patterns with the same Y coordinate described in the prior art, and fine adjustments are made using the same method as in the prior art. I do.

As described above, according to this embodiment, by using the pattern formed on the mask blank itself for O adjustment, it is possible to easily perform O adjustment even when a pattern suitable for O adjustment such as a scribe line does not exist. This can shorten the time required for adjustment.

Furthermore, the regions (rectangular patterns) 3 and 4 on the upper and lower sides where no light-shielding film is formed are used as scales for positional coordinates within the mask dry plate, but may be omitted for the purpose of the present invention.

In addition, in addition to the regions 1 to 4 where no light shielding film is formed, many more regions (rectangular patterns) where no light shielding film is formed may be formed for use as scales. The sizes of a and b in areas 1 to 4 where the light-shielding film is not formed are determined by taking into consideration the pattern formation area of the mask dry plate, the magnification of the microscope of the inspection device, the structure of the mask holder, and the method of attaching the mask. .

(Effects of the Invention) As is clear from the Examples described above, the mask blank of the present invention has a region on the glass substrate where no light-shielding film is formed, and this region can be used as an O rough adjustment pattern for an inspection device, etc. This has the effect that the O adjustment can be easily performed and the adjustment time can be shortened. Furthermore, since there is no need to specially form a pattern for θ adjustment during mask production, there is an effect that the number of mask production steps does not increase.

Note that the area j-1,1 can be used as a scale for position coordinates regarding the pattern within the mask reticle.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a mask blank according to an embodiment of the present invention, FIG. 2 is a diagram showing a method for coarse zero adjustment, and FIG.
It is a figure which shows the method of fine adjustment. 1.2, 3.4...Region where no light shielding film is formed (rectangular pattern), 5,6... Mask position during O rough adjustment, 7,8... Pattern used for θ fine adjustment. Patent applicant Matsushita Electronics Co., Ltd.

Claims (2)

[Claims] (1) A mask blank characterized by having a plurality of regions on a glass substrate where no light shielding film is formed. (2) The mask blank according to claim (1), wherein the region where the light shielding film is not formed is a rectangle located at the center of the plurality of sides of the glass substrate.