JPS5932892B2 - Wafer alignment method - Google Patents

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 film on its surface is placed on a wafer mounting table, a mask with a predetermined pattern is placed on top of this wafer, and the two are brought into close contact to form a pattern on the mask. Bake onto the photoresist layer on the wafer.

At this time, the air that exists between the wafer and the mask becomes partially sealed, and it takes time to maintain the two in a predetermined position and create a seal. 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. 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 a wafer mounting table having an air outlet in the center and an air suction port in the periphery. 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 mutual separation (separation) of the wafer and mask becomes extremely easy. 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. The air outlets 12 communicate with each other through an annular communication hole 14 and are connected to a compressed air source through a communication hole 16 that opens on the side surface of the mounting table 11. Further, the air suction ports 13 are communicated with each other through an annular communication hole 17, and are connected to a vacuum device through a communication hole 18 opened in the side surface of the mounting table 11 in the same manner as described above. Wafer mounting table 1
A wafer 21 having a photoresist layer on its surface is placed on top of the wafer 1, and a mask 22 is further placed on top of the wafer 21.

The wafer 21 is, for example, a semiconductor wafer, and the mask 2
2 can be, for example, a chrome mask. and wafer 2
1 and the 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, so that the wafer 21 is moved to the center as shown in the figure. is raised upward, and the peripheral portion is adsorbed onto the wafer mounting table 11. In this way, when the wafer 21 is deflected and the mask 22 is placed on top of the wafer 21, the two will come into contact only at the central raised part of the wafer 21, and no air will be sealed between them. Therefore, the mask 22 can be easily positioned at a predetermined position on the wafer 21. 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 will easily transition to a close contact state from the center to the periphery. After the pattern of the mask 22 is printed and exposed on the wafer 21, air is again blown out from the air outlet 12 and air is sucked in from the air suction port 13 to warp and deform the wafer 21 as shown in the figure to separate the mask. conduct.

Also in this case, since air can freely enter between the wafer 21 and the mask 22 from the peripheral direction, the mask 22 can be easily separated from the wafer 21. As described above, according to the present invention, it is possible to provide a wafer alignment method that allows easy separation of a wafer placed on a wafer mounting table and a mask.

Further, according to the method of the present invention, since the resist is gradually peeled off from the periphery, it is possible to prevent the resist from sticking to the mask.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing an example of a wafer aligning apparatus used for carrying out the present invention, and FIG. 2 is a plan view taken from line 15 in FIG. 1.

Claims (1)

[Claims] 1 (a) Step of aligning the relative positions of the wafer and mask (b) Step of exposing the wafer and mask while bringing them into close contact (c) Protruding the center of the wafer and gradually increasing the distance between the wafer and the mask from the periphery of the wafer A wafer alignment method comprising a step of introducing gas into the wafer and (d) a step of completely separating the wafer and the mask.