JPS5980930A - Aligning method of wafer - Google Patents

Abstract

PURPOSE:To obtain a method through which a wafer and a mask are fast stuck and separated easily by projecting the central section of the wafer to bring the wafer into contact with the mask and slowly flattening the wafer so that a closely adhesive surface with the mask spreads to a peripheral section from the central section of the wafer. CONSTITUTION:When the wafer and the mask are fast stuck, air is blown off from air blow-off ports 12 and air is sucked from air suction ports 13, the central section of the wafer 21 is projected upward, and the peripheral section is adsorbed onto a wafer base plate 11. Consequently, when the wafer 21 is projected and the mask 22 is placed on the wafer 21, both are in contact only in the central projecting section of the wafer 21, and air is not brought to a sealed state between both, thus easily positioning the mask 22 at a predetermined position on the wafer 21. When the blow-off of air and the suction of air are stopped and the projecting deformation of the wafer 21 is released, the wafer 21 and the mask 22 shift easily to the closely adhesive state to the peripheral section from the central section.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to wafer alignment for aligning a mask having a predetermined pattern to a semiconductor wafer.

In this type of wafer alignment, a semiconductor wafer having a photoresist layer on its surface is placed on a wafer mounting table, a mask having a predetermined pattern is placed on top of this wafer, and both are placed in close contact with each other. pattern is baked into the photoresist layer on the wafer. At this time, the air existing between the wafer and the mask becomes partially sealed, and it takes time to maintain the two in a predetermined position and bring them into contact. When separating the mask from the wafer, it takes time to separate the mask because it is difficult for air to enter between the two. This difficulty in separating is particularly remarkable when a chrome mask is used and a vacuum sealing method is used.

SUMMARY OF THE INVENTION An object of the present invention is to provide a wafer alignment method that allows a wafer placed on a wafer mounting table to be brought into close contact with a mask and to easily separate the wafer and the mask.

In order to achieve this object, the wafer alignment method according to the present invention includes a wafer mounting table having an air outlet in the center and an air suction port in the periphery, and an upper surface of the wafer placed on the wafer mounting table. A mask placed on the wafer mounting table, a means for blowing air from the air outlet, and a means for sucking air from the air suction port are prepared, and the wafer placed on the wafer mounting table is placed in the air outlet. The center portion is raised by the air blowing action from the opening, and the peripheral portion is attracted onto the wafer mounting table by the air suction action from the air suction port. By causing the wafer warpage, the wafer and mask are brought into close contact with each other.

In FIGS. 1 and 2, reference numeral 11 denotes a wafer mounting table used for carrying out the present invention. The wafer mounting table 11 is provided with a plurality of air blowing ports 12 at appropriate intervals in the center thereof, and air suction ports 13 are provided in the periphery thereof distributed at approximately equal intervals in the circumferential direction. Each air outlet 12 communicates with each other via an annular communication hole 14, and the mounting table 1
It is connected to the compressed air plate through a communication hole 16 that opens on one side. Furthermore, each air suction port 13 has an annular communication hole 17.
, and connected to the vacuum device through the communication hole 18 opened in the side surface of the mounting table 11 in the same way as described above.

A wafer 21 having a photoresist layer on its surface is placed on the wafer mounting table 11, and a mask 22 is placed on top of the wafer 21. The wafer 21 may be, for example, a semiconductor wafer, and the mask 22 may be, for example, a chrome mask. The wafer 21 and mask 22 can be brought onto and from the wafer mounting table 11 using a vacuum chuck or vacuum tweezers.

Now, after the alignment of the wafer and the mask is completed, when the wafer and the mask are brought into close contact with each other, air is blown out from the air outlet 12 and air is sucked in from the air suction port 13 to move the wafer 21 to the central part as shown in the figure. is raised upward, and the peripheral portion is adsorbed onto the wafer mounting table 11. In this way, the wafer 21 is kept deflected and the mask 2
When the mask 2 is placed on the wafer 21, the two come into contact only at the central raised part of the wafer 21, and there is no air seal between the two, so it is easy to place the mask 22 in a predetermined position on the wafer 21. Traps can be placed. Thereafter, if air blowing and air suction are stopped to release the bulging deformation of the wafer 21, the wafer 21 and the mask 22 can easily be brought into close contact from the center to the periphery.

As described above, according to the present invention, it is possible to provide a wafer alignment method that facilitates close contact between a wafer placed on a wafer mounting table and a mask.

Further, according to the method of the present invention, since there is no possibility that gas remains on the contact surface between the wafer and the mask, that is, on the resist surface, highly accurate exposure can be performed.

Furthermore, since there is no residual gas, problems such as gas movement and changes in adhesion during exposure do not occur.

Furthermore, in the present invention, residual gas is removed without difficulty by utilizing the warping of the sea urchin, so that deformation of the resist pattern does not occur.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing an example of a wafer alignment apparatus used for carrying out the present invention, and FIG. 2 is a plan view taken from the lines 1 and 2 in FIG. Explanation of symbols 11... Wafer mounting table, 12... Air outlet, 1
3... Air intake port, 14.16, 17.18...
Communication hole, 21... wafer, 22... mask.

Claims (1)

[Claims] 1. (a) Step of aligning the relative positions of the wafer and mask (b) Step of reducing the distance between the surfaces of the wafer and mask (C) Protruding the central part of the attracted sea urchin (d) bringing the wafer into contact with the mask; a wafer alignment method comprising the step of gradually flattening the wafer so that the surface in close contact with the mask spreads from the center of the wafer to the periphery;