JPS6344220B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an electron beam exposure method for forming a pattern on a photomask, and more particularly to a method for checking pattern accuracy in electron beam exposure.

[Conventional technology]

When manufacturing semiconductor devices such as integrated circuits, pattern formation is generally performed using photolithography technology.

In recent years, while the degree of integration of this type of device has increased, the quality accuracy of photomasks such as pattern accuracy and overlay accuracy has been increasing, and the manufacturing process has also become more complicated. For this reason, electron beam exposure equipment that allows easy microfabrication and high-precision, high-speed mask making has begun to be used. Electron beam exposure equipment (EB exposure equipment) creates photomasks by continuously exposing each chip with a predetermined scan width according to EB data.

A conventional method for manufacturing and inspecting a photomask will be described below. An example is shown in FIG.
As shown in the figure, the raster scan type EB exposure apparatus scans the raster 3 with a predetermined scan width while exposing the entire surface of the photomask 1 to form the pattern 2. Therefore, since the data of one chip is divided into a number of stripes and exposed, the joints of the stripes within the chip always become a problem. Also, unlike the conventional method of creating photomasks using light, pattern guarantees are a problem because they are created according to EB data each time. Since photomasks are created in this way, it is essential to inspect the pattern joints every time, and this must be ensured for all stripes. Furthermore, with conventional methods, there is no way to accurately measure the scan width, making measurement impossible.

As described above, the conventional photomask manufacturing method has the disadvantage that it is not possible to accurately measure the joint portion and scan width for each mask, and it is not possible to create a highly accurate photomask.

[Summary of the invention]

This invention was made to eliminate the above-mentioned drawbacks, and it is possible to arrange a monitor pattern outside of the regular array other than the regular pattern, and in particular, to draw this monitor pattern before and after the exposure of the regular pattern. It is an object of the present invention to provide an electron beam exposure method for forming a photomask that allows confirmation and inspection of the accuracy of electron beam exposure.

[Embodiments of the invention]

Examples will be described below. FIG. 2 is a diagram showing an embodiment of the photomask manufacturing method according to the present invention. First, monitor patterns 4-1, 4-2, 4-3, 4-4 are drawn according to the EB data, but each monitor pattern 4-1, 4-2, 4-
3, 4-4 are four 4A, as shown in the lower right of Figure 2.
It is divided into 4A', 4B, and 4B',
They are provided at the four corners of the mask 1.

First, monitor pattern 4- on the lower left of mask 1
The lower left part 4A of 1 is exposed with a scan width of 5, and in the same way, the lower left part 4A of the lower right monitor pattern 4-2, the lower left part 4A of the upper right monitor pattern 4-3, and the lower left of the upper left monitor pattern 4-4 are exposed in the same way. Part 4
Expose with A. Next, the upper left portion 4A' of the monitor pattern 4-1 at the lower left of the mask 1 is exposed with the same scan width as above. The scan width is the same as above, but the exposed portion is only a quarter width of the lower end as shown. Similarly, lower right, upper right, upper left monitor patterns 4-2, 4-
3, the upper left portion 4A' of 4-4 is scanned and exposed.

In this way, monitor pattern 4-
After the exposure of each left side portion 1, 4-2, 4-3, and 4-4 is completed, the main pattern 2 is sequentially exposed over the entire surface of the mask 1. After completing the exposure of main pattern 2 according to the EB data, monitor pattern 4-
1, 4-2, 4-3, and 4-4 are exposed.

In other words, the lower right portion 4B of the lower left monitor pattern 4-1 of the four locations is scanned and exposed, and the same portions as lower right 4-2, upper right 4-3, and upper left 4-4 are sequentially scanned and exposed. do. Finally, the upper right part 4B' of the monitor pattern is sequentially moved from the lower left 4-1 to the lower right 4-2 of the four monitor patterns.
Expose upper right 4-3 and upper left 4-4.

If such a method is adopted, it is possible to always check the joint portion of the stripes, and it is also possible to check the precision within the stripes and at the interfaces of the stripes. Monitor pattern 4-1, 4-
Since 2, 4-3, and 4-4 are exposed at the beginning and end of exposure, the amount of long-term drift of the mask pattern can be determined from the positional deviations of 4A, 4A', 4B, and 4B'.

In the above embodiment, the monitor patterns are arranged at four locations within the mask, but other arrangements may be used and the same effect will be achieved.

Also, the monitor patterns are 4A, 4A', 4B,
Although the method of dividing 4B' into two and using two stripes has been described, other methods can also produce similar effects. Furthermore, although the pattern shape in the monitor pattern has been described with respect to the pattern shown in the figure, other patterns may also produce similar effects.

〔Effect of the invention〕

According to the present invention, it is possible to accurately and quantitatively grasp the accuracy of electron beam exposure produced by an EB exposure apparatus, making it easier to produce a high-quality photomask. In particular, the amount of long-term drift of the mask pattern, which is a problem in EB exposure equipment, can be accurately determined by checking the positional shift of the monitor pattern, and is a very effective means for checking the accuracy of the equipment. The time required to actually draw and expose the monitor pattern is extremely short, and there is no problem in drawing and exposing the main pattern.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a method for creating an EB photomask and a photomask using a conventional EB exposure apparatus, and FIG. 2 is an explanatory diagram showing a photomask and a drawing method using an EB exposure apparatus according to the present invention. In the figure, 1 is a photomask, 2 is a regular pattern, 3 is a raster, 4-1, 4-2, 4-3, 4
-4 is a monitor pattern, 4A, 4A', 4B,
4B' is a check pattern in the monitor pattern,
5 is a stripe. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1 In the electron beam exposure method in which a monitor pattern for checking the accuracy of electron beam exposure is formed by exposure other than a regular pattern, when the regular pattern is formed by scanning the electron beam for a predetermined number of stripes, the regular pattern is formed. In the scanning of stripes to be scanned, scanning for forming a monitor pattern is performed before and after forming a regular pattern to form two monitor patterns, and these two monitor patterns are formed adjacently or in the vicinity. An electron beam exposure method comprising: