JPS5823930B2 - Densibee Murokousouchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for eliminating the effects of distortion occurring in an electron optical system of an electron beam exposure apparatus.

In order to manufacture microcircuits, microprocessing (exposure) is performed by irradiating an electron beam onto the surface of a target wafer made of silicon or the like.

The beam exposure area on such a target surface has a pattern of a desired circuit, but in order to increase the number of circuit elements included in a microcircuit, the exposure pattern on the target surface must be made finer. Or, it becomes necessary to enlarge the exposure area.

In any of these cases, it is required to suppress exposure errors occurring in electron beam processing as low as possible.

FIG. 1 shows an example of an electron beam exposure apparatus used for manufacturing microcircuits, etc., in which a target 3 is processed with an electron beam 2 from an electron gun 1.

In the figure, an electron beam 2 generated from an electron gun is turned into a parallel beam by a two-stage electron lens, passes through a projection mask 6, and then is irradiated onto a target 3 as a narrow-width parallel electron beam by a two-stage reduction lens 7.8.

The projection mask 6 is provided with grooves in the form of a circuit pattern, and only the electron beam that passes through the grooves reaches the target 3, and the pattern of the projection mask 6 is exposed on the Kugets I-plane. Ru.

A reduction lens 7 between the projection mask 6 and the target 3.
8 is provided in order to reduce the projection mask pattern created to a size that can be easily processed on the target surface, but the lens aberration in these electron lenses 7 and 8 is large. The similarity between the pattern of the projection mask and the pattern exposed on the target surface cannot be maintained sufficiently, causing large processing errors, and it becomes impossible to expose fine patterns beyond a certain limit.

FIG. 2 is for explaining lens distortion in the reduction lens system, where a indicates the outer periphery of the pattern of the projection mask 6,
b indicates the outer periphery of the pattern exposed to the target 3 when using the mask a.

It can be seen from FIG. 2 that the outer periphery of the square pattern on the projection mask is distorted into a barrel shape on the target due to lens aberration when exposed.

Furthermore, depending on the type of reduction lens system actually used, various distortions other than barrel distortion may occur, such as pincushion distortion tube distortion.

The present invention measures the distortion of the pattern exposed on the target surface in advance, and corrects the pattern shape of the projection mask in advance so as to cancel out such distortion, thereby forming the desired pattern on the target surface. The pattern is exposed.

For example, if distortion as shown in Fig. 2 occurs, if a mask with a corrected pattern as shown in Fig. 3a is used as a projection mask, the image shown in Fig. 3 can be projected onto the target surface. A desired pattern as shown in can be obtained.

The above embodiment corrects distortion in a plane perpendicular to the optical axis of the electron optical system, but distortion in the optical axis direction that causes blurring at the peripheral edge of the pattern exposed on the target surface is a problem. In this case, the distortion can be corrected by inserting the projection mask 10 in a curved manner with respect to the optical axis 9, as shown in FIG.

As explained in detail above, the method of the present invention makes it possible to remove unavoidable distortions that occur in electron optical systems very easily, so that great effects can be obtained in the manufacture of microcircuits using electron beam exposure equipment.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing an electron beam exposure device, and Fig. 2 is a schematic diagram showing an electron beam exposure device.
FIGS. 3 and 4 are schematic diagrams for explaining the distortion occurring in the apparatus shown in the figure, and FIGS. 3 and 4 are diagrams for explaining the present invention in detail. 1...Electron gun, 3...Target wafer, 4°5.6, 7.8...Electron lens, 9.
...Optical axis, 10...Projection mask.

Claims (1)

[Claims] 1. In an apparatus in which a mask having a pattern to be exposed is irradiated with an electron beam, and the electron beam transmitted through the mask is reduced and imaged by an electron lens and projected onto a target, the pattern of the mask is An electron beam exposure apparatus characterized by having a shape that corrects distortion of an electron optical system including a lens.