JPS59105319A - Exposure method - Google Patents

Abstract

PURPOSE:To improve closely adhesive property between a wafer and a mask, to align them with high accuracy and to execute exposure treatment of a high resolution by exposing the wafer step by step at every partial region of the wafer. CONSTITUTION:The mask 2 has an area considerably smaller than the whole area of the wafer 1, and each exposes only small section regions of the wafer 1 through once exposure operation. Beams from a light source 3 to the mask are irradiated to the mask 2 as condensed beams through an optical system for condensing beams such as a lens 4. In the partial exposure operation, the degree of close adhesion between the mask 2 and wafer 1 in an exposure region is improved by partially blowing up only a blow-up region by high-pressure air by using a chuck 6 in a region such as a region under exposure. Accordingly, when exposure in one small section region is completed, the wafer 1 is moved, and positioned at a desired exposure position.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exposure method, and particularly to an exposure method that can perform contact exposure on a semiconductor wafer with high density and high resolution.

Conventionally, when printing integrated circuit patterns on semiconductor wafers using exposure processing in the manufacturing process of semiconductor products, there are two methods: contact exposure, in which a mask is placed in close contact with the circuit pattern forming surface of the wafer, and contact exposure, in which the mask and wafer are placed apart. A method is known in which a mask pattern is projected onto a wafer and then exposed to light.

Of these, in the former contact exposure method, conventionally, the other side of the wafer is exposed all at once in one exposure operation.

However, with this conventional method, several problems have arisen as wafers become larger and circuit patterns become finer. First of all, as the size of the wafer increases, the degree of adhesion between the wafer and the mask decreases, which adversely affects the resolution. ′! In addition, the increase in the size of the wafer causes expansion and contraction of the wafer and an increase in pitch deviation during contact printing, making it difficult to uniformly and accurately align the entire surface of the wafer.

An object of the present invention is to solve the above-mentioned problems of the prior art, to improve the adhesion between a wafer and a mask, to perform high-precision alignment, and to perform high-resolution exposure processing. Our goal is to provide the following.

Hereinafter, the present invention will be explained in detail according to an embodiment shown in the drawings.

FIG. 1 is a side view showing an embodiment of the exposure method according to the present invention.

In this embodiment, the exposure is performed by a contact exposure method in which the mask and the wafer are in close contact with each other, and the exposure is performed by dividing the entire wafer into a plurality of small regions, and performing one exposure for each small region. The exposure process is performed in a stepwise manner by performing the following exposure operations.

That is, in the exposure method of this embodiment, the mask 2 has a considerably smaller area than the overall area of the wafer 1;
Only small sections of the wafer 1 are exposed in one exposure operation. In this case, since the area of the mask 2 is small, the light from the light source 3 directed toward the mask passes through a condensing optical system such as a lens 4 and is irradiated onto the mask 2 as condensed light. In addition, in this partial exposure operation, the area being exposed can be removed by blowing up only the blow-up area 5a in FIG. 1 with high-pressure air using a chuck 6 as shown in FIG. The degree of adhesion between the mask 2 and the wafer 1 is increased.

In FIG. 2, 7 is a mask holder, and this mask holder 7 has a vacuum exhaust path 8.

On the other hand, the wafer 1 is placed on the chuck 6, and the chuck 6
By performing vacuum suction and supplying high-pressure air through vacuum suction holes 9' provided in the wafer 1, the wafer 1 can be vacuum suctioned and the wafer 1 can be blown into close contact with one mask 2. The lower surface of the mask 2, that is, the surface in close contact with the exposure surface of the upper surface of the wafer 1, is a patterned surface that protrudes downward from the other surfaces as shown by 2a in FIG. It is brought into close contact with the exposed area of the mask 1 at 2a.

After completing the exposure of one sub-area in this way,
The mask 2 is brought to a desired exposure position relative to the wafer 1 by, for example, moving the wafer 1 so as to expose the area indicated by the dashed line in FIG. Then, only the blow-up area 5b around the exposed area by this mask 2 is removed by a chuck 6.
By blowing up high-pressure air from the vacuum suction hole 9, the exposure area of the wafer 1 is brought into close contact with the turn surface 2a of the mask 2, and the required exposure process is performed.

Furthermore, when performing the next exposure process, the mask 1 is moved and positioned so that the mask 2 is in the area shown by the two-dot chain line in FIG. By blowing up only the area 5C, the exposure area of the wafer 1 and the turn surface 2a of the mask 2 are brought into close contact, forming a hole.
Exposure with condensed light is performed as in the case of the area described above.

According to this embodiment, since it is a Nutep exposure method in which exposure is performed in one exposure operation for each 7J'% segmented area of the Ueno 1, the contact area between the Ueno 11 and the mask 2 is small.
The degree of adhesion between the two is increased, and high resolution can be obtained. especially,
By blowing up only the blow-up area around each exposure area with high-pressure air, it is possible to further increase the degree of adhesion between the mask 1 and the mask 2.

Moreover, even though it is affected by pitch deviation and expansion/contraction of the ueno 1, uniform high alignment accuracy can be obtained for the ueno as a whole.

Furthermore, in this embodiment, the mask 2 has a smaller area than the mask 1, and condensed light can be used as exposure light, so that the exposure intensity can be increased and the resolution can be improved.

Furthermore, in this embodiment, the image shift phenomenon at the time of contact between the wafer 1 and the mask 2 can be reduced, making it possible to improve throughput and reduce defect density.

one! ! In this embodiment, the entire bottom surface of the wafer 1 can be vacuum-adsorbed by the chuck 6 and separated from the mask 2, so that sticking can be reduced.

Note that the present invention is not limited to the above embodiments,
Various other variations are possible.

As described above, according to the present invention, high adhesion and high alignment accuracy can be obtained, and exposure processing with high resolution can be performed.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of the exposure method according to the present invention, and FIG. 2 is a partial cross-sectional view showing the state of contact between a wafer and a mask. l...Wafer, 2...Mask, 3...IL 4
...lens, 5a151), 5c... blow-up area,
6... Chuck, 7... Mask holder, 8... Vacuum exhaust path, 9... Vacuum suction hole. Figure 1 Figure 2

Claims (1)

[Claims] 1. An exposure method using contact exposure, which is characterized in that step exposure is performed for each partial region of a wafer. 2. The exposure method according to claim 1, characterized in that condensed light is used as the exposure light. 3. The exposure method according to claim 1, characterized in that the entire wafer in the contact area with the mask is lifted up and the blown-up area of the wafer is brought into close contact with the mask.