JPS599663A - Reduction projecting and exposing method - Google Patents

Abstract

PURPOSE:To minimize the influence of dust sticking to a mask, by using plural masks and reducing transmitted energy per mask, and exposing the same position of a substrate several times. CONSTITUTION:An image obtained by a photomask 1 is reduced by a lens system 2 and projected on the substrate 3 by one shot to complete an exposure pattern. N Sets of masks 1 having the same pattern are used to reduce the amount of exposure per mask to 1/N as great as the basic amount of exposure and the substrate 3 is exposed to a one-shot image; and the substrate 3 is moved in an x-axis and a y-axis direction to form exposure patterns 4a-4c over the entire surface of the substrate successively for entire-surface exposure. Further, a prepared photomask 1 is replaced and the same operation is repeated by N times for superposition exposure. In this case, plural lens systems may be used to perform plural exposure shots simultaneously or to superpose images of those lens systems optically. Thus, the influence of dust sticking to a mask is minimized as much as possible.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a reduction projection exposure method in which a pattern obtained in the above is reduced and projected onto a substrate to form a pattern rJy.

Although the reduction projection exposure method can form highly accurate patterns, the dirt caused by dust on the mask is transferred to all chips on the substrate in the same way. Cleaning, maintenance and management of clean conditions are required, which poses a major problem in the manufacture of semiconductor devices.

The present invention solves the above-mentioned problems (by using a plurality of first masks having the same pattern and reducing the transmitted energy per photomask, multiple exposures are overlapped at the same position on the substrate to form a single photomask). It is characterized by forming a pattern.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In the reduction projection exposure method, an area corresponding to one nanoyot is exposed based on the light energy determined by the product of the light meter transmitted through one photomask 1 and time. Therefore, when exposing with reduced light energy, it is sufficient to increase the exposure time in the same area with the same pattern by the amount that the light energy has been reduced.

On the other hand, the positions of dust adhering to the surfaces of multiple masks having the same pattern are generally random, and the probability of them being at the same position is extremely low.

Therefore, in consideration of the above, the present invention provides N(*dashiN
Using 1.2...n) masks with the same pattern, the transmission energy per mask is reduced to 11/N, and each mask transmits the same pattern to the same position K on the substrate.
Exposure is performed N times overlappingly.

FIG. 1 is a diagram showing the principle of the basic reduction projection exposure method. Conventionally, the array obtained with a photomask 1 is reduced by passing through the entire lens thread 2 to form an exposure pattern on the substrate 3 one shot at a time. 3 f Exposure patterns 4a, 4b, and 4ci are sequentially formed on the entire surface of the substrate by moving in the x and y axis directions, and once the entire surface is exposed, the exposure is completed. There is no need to re-expose.

The basic operation of the first embodiment of the present invention is the same as the above-mentioned basic exposure method, so it will be explained with reference to FIG. 1. In the present invention, the exposure amount per photomask is calculated based on the exposure amount of the basic exposure method (hereinafter referred to as basic exposure j5) and the number of photo masks (N, blow) of the same pattern prepared. After the entire surface of the substrate is exposed, the prepared photomask 1 is replaced and the same exposure pattern 4 av 4 b + 40 is placed on the substrate B.
- The pattern is sequentially exposed N times to complete the exposure of the entire surface of the substrate.

In the second embodiment of the present invention, as shown in FIG. 2, each of the N photomasks 1 is provided with a lens system 2, and the N photomasks 1 are changed one time at a time by 1/N of the basic exposure amount. The substrate '5 is exposed one by one by a ton' each by exposing N shots at the same time.
4a, 41), 4 on the substrate B by moving the
The exposure is repeated N times with the same pattern using different masks at position C.

In the sixth embodiment of the present invention, as shown in FIG. 3, N photomasks 1 are each equipped with a lens system 2, and the exposure amount per photomask is reduced to 1/N of the basic exposure sensitivity. The light transmitted through all N photomasks at the same time is optically combined to perform exposure for one shot, and the substrate is sequentially moved to complete the exposure of the entire surface of the substrate.

As described above, the present invention uses a mask having N four-no-turns and transmits the transmission energy v1/
Since the same no-turn is exposed N times at the same position on the substrate using each mask, the degree of shadow transferred to the same position due to dust attached to the mask is reduced to 1/N.
This has the effect of minimizing the influence of comics.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the principle of the reduction projection method and is also an explanatory diagram of the principle of the first embodiment of the present invention, and FIG. 2 is a diagram showing the principle of the first embodiment of the present invention.
FIG. 3 is a diagram explaining the principle of the third embodiment of the present invention. 1... Photomask 6... Substrate patent applicant
Naka Kanno, patent attorney representing NEC Corporation

Claims (1)

[Claims] (1) N (i LN'=1, 2・n) identical patterns:! A reduction projection exposure method characterized in that the same pattern is exposed N times at the same position on a substrate using each mask by using a mask having an illumination of 1/200 nm and reducing the transmission energy per mask to 1/N. .