JPS59155131A - Method for contact exposure - Google Patents

Abstract

PURPOSE:To easily form a sufficiently close-contact condition between a mask and a wafer by a method wherein the first vent group for the center part of the wafer and the second vent group for the circumferential part of the wafer are provided on the main part of the wafer chuck, and the operation by each vent group is controlled independently. CONSTITUTION:On the wafer chuck main body 12, the first vent group 10a to be used for flowout and sucking of the center part of a semiconductor wafer 12 and the second vent group 10b to be used for flowout and sucking of the circumferential part of the wafer 12 are provided. A light source to be used for exposure, which is not shown in the diagram, is arranged above the mask 14 for exposure which will be used for close-contact and isolation of the wafer 12, and it is made to irradiate on the photoresist material through the intermediary of the mask 14. When the wafer 12 is going to be close-contacted to the mask 14 for exposure, a blow-up and close-contact operation has priority to the blow-up and close-contact operation to be performed through the intermediary of the second vent group 10b.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a mask aligner used, for example, in manufacturing various semiconductor devices, and in particular, in a mask aligner, a semiconductor wafer is brought into close contact with an exposure mask, and a semiconductor wafer is removed from an exposure mask. This invention relates to improvements in wafer adhesion/separation mechanisms for separating wafers.

Conventionally, this type of wafer adhesion/separation mechanism has a number of vent holes in the wafer chuck body, and when the semiconductor UNO is brought into close contact with the mask, compressed gas is blown up from the vent holes to separate the UNO from the mask. It is also known that the wafer is sucked through the ventilation hole when the wafer is removed.
In this type of mechanism, if you want to achieve even stricter adhesion when adhering the wafer to the mask, you can strengthen the adhesion using atmospheric pressure in a predetermined space surrounding the mask under reduced pressure, or It is also known to apply an external mechanical force between the chuck and the mask.

However, in the conventional wafer adhesion/separation mechanism, it is still difficult to form sufficient adhesion between the mask and the wafer, especially at the center of the wafer, even with such adhesion reinforcement means. In other words, the surface of the semiconductor wafer that is the target of mask alignment is usually mirror-polished and covered with a photoresist agent, and the mirror-polished wafer surface has a periphery that is about 10 μm higher than the center (has an uneven shape). When such a wafer is pressed against a mask using a wafer chuck with a nearly uniform blowing pressure, the unino and peripheral parts adhere preferentially to the mask surface via the photoresist agent, and the unino Gas is trapped between the center and the mask surface, creating a gap. This gap is in a sealed state because the inner and peripheral parts are in close contact with the mask, so it does not blow up. Simply increasing the pressure.

It was difficult to eliminate. Therefore, the degree of adhesion between the wafer and the mask deteriorates, particularly in the central part of the wafer, resulting in poor resolution of the mask cross-turn.

In addition, the above-mentioned gap between the masks acted to prevent the separation of the wafer from the mask.
It was not easy to separate the wafer using the conventional UNINO, close contact, and separation mechanism.In other words, when trying to separate the UNINO from the mask using a nearly uniform suction force using a wafer chuck,
The so-called sticking phenomenon occurs mainly because the central part of the Uni-No-O leaves the mask surface first, and a depressurized part is formed in the part corresponding to the above-mentioned void. For this reason, it was often difficult to separate sea urchins using just the suction force of the sea urchin chaff.

The purpose of this invention is to overcome the above-mentioned difficulties of the prior art,
An object of the present invention is to provide a novel mask aligner that can easily form a sufficient adhesion state between a mask and a wafer, and can easily and smoothly separate the mask from the wafer.

One of the features of this invention is that a first group of ventilation holes for blowing up or suctioning the central part of the wafer and a second group of ventilation holes for blowing up or suctioning the peripheral part of the wafer are connected to the wafer chuck. is provided in the main body to independently control blow-up close contact operation and/or suction separation operation by the first group of vent holes and similar operation by the second group of vent holes when adhering to and/or separating the sea urchins. It's at the point where it hangs. Here, the term "vent hole group" originally means a group of a large number of vent holes, but in this specification, in addition to its original meaning, it also refers to a group corresponding to the center or peripheral part of the wafer. and the predetermined pattern (
According to one of the features of this invention, which is used to include 1115 ventilation holes in appearance that are continuously formed in the form of a ring (for example, a ring shape), separate A blow-up contact operation or a suction separation operation can be performed, and the strength of the contact force or suction force at that time can be adjusted separately. For this reason, there are many control modes, and it becomes possible to perform adhesion/separation operations that suit the size, shape, characteristics, etc. of UNINO.1 For example, when bringing UNINO 1 into close contact with the mask, the first ventilation hole Control can be performed so that a blow-up contact operation performed through the group is given priority over a similar operation performed through the second vent group. When such a control method is used, the center of the wafer comes into close contact with the mask surface before the periphery, so no gap is formed between the mask and the wafer, and the wafer as a whole can achieve sufficient adhesion. I can do it. Therefore, the resolution failure of the mask pattern is greatly reduced. On the other hand, when separating the wafer from the mask, the suction separation operation performed through the second ventilation hole group is similarly performed through the first ventilation hole group. Control can be performed to give priority to other operations. If such a control method is used, the periphery of the 5 wafers will separate from the mask surface before the center, so no depressurized area will be formed between the mask and the wafer, and the 1 minute wear process will be performed easily and smoothly. be exposed.

An embodiment of the present invention will be described below with reference to the accompanying drawings. In the figure, 10 is the Uni-no-chuck body,
This includes a first group of ventilation holes 10a for blowing up and suctioning the central part of the semiconductor wafer 12, and a second group of ventilation holes 10b for blowing up and suctioning the peripheral part of the wafer 12. ing. The exposure mask 14, which is the object of adhesion and separation of the wafer 12, is made of a suitable glass plate, and its lower surface (
A suitable pattern made of chromium (Cr) or the like is deposited on the wafer adhesion surface. 1 above the mask 14
An exposure light source 112 (not shown) is arranged to irradiate the photoresist agent coated on the surface of the wafer 12 through the mask 14. Prior to the exposure process, the unit 112 is brought into close contact with the lower surface of the mask 14, and is exposed to light. Mask 1 after processing
Separated from 4.

Close contact operation of wafer 12 to mask 14 and wafer 1
The separation operation of the mask 2 from the mask 14 is performed by the following mechanism. The switching device 16rr controls whether to supply compressed gas consisting of nitrogen (N) to the pipe 20.22 or to draw the pipe 20.22 with a vacuum VAC according to a switching command from the control system 18. The piping 20 has a solenoid valve 24 cut in the middle thereof, and is connected to the first group of ventilation holes 10a of the wafer chuck body 10. A solenoid valve 26 is provided in the middle of the pipe 22, and the pipe 22 is connected to the second vent group 10b of the wafer chuck body 10. Solenoid valve 2
4.26H are all operated in response to control signals from the control system 18.

When bringing the wafer 12 into close contact with the mask 14,
First, the switching device 16 is used to flow N2 pressure gas to the pipes 20 and 22, and the solenoid valve 24 is opened. After a predetermined time (for example, 2 to 3 seconds), the solenoid valve 26 is opened (so that the control system 18 In this way, as shown by the broken line, the central part of the wafer 12 comes into close contact with the mask surface first, and the gas in the central part is expelled to the periphery, and the gas in the central part is then driven out to the periphery.
The peripheral portion comes into close contact with the mask surface, and therefore, the entire surface of the UNINO'-12 comes into close contact with the mask 14 without leaving any gas or voids in the central portion. Therefore, under such good adhesion conditions.

Mask pattern printing (exposure) processing can be performed with high resolution. In addition, during the above-mentioned blow-up close contact operation, in order to reinforce the close contact force, the force of vacuum or atmospheric pressure or external mechanical force may be used in combination.

Next, when separating the UNINO S12 from the mask 14, C1, connect the piping side to the vacuum VAC using the switching device 16, and then open the solenoid valve 26 (after S, open the solenoid valve 24 after a predetermined time). It is controlled by the control system 18 as follows.

In this way, as shown by the broken line, the peripheral part of the Uni-No-S12 first separates from the mask 14 to promote gas flow to the central part, and then the central part of the Uni-No-S12 separates from the mask 14. Therefore, it is separated from the mask 14 smoothly as a whole. Therefore, wafer separation can be easily achieved without causing the sticking phenomenon as in the prior art.

In addition, in the above description of the embodiment, the ventilation hole group 10a or 10b formed in the Uni/S chuck body 10 may be one ventilation hole having a connected pattern when viewed from the wafer 12 side, and The adhesion force or suction force during the adhesion/separation operation may be controlled differently between the central vent side and the peripheral vent side.

[Brief explanation of the drawing]

The figure is a sectional view showing a wafer adhesion/separation mechanism of a mask aligner according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 10... Wafer chuck main body, 10a... 1st vent hole group, 10b... 2nd vent hole group, 12... Semiconductor unit. 14...Mask for exposure.

Claims (1)

[Claims] 1. A wafer chuck is provided with a first group of ventilation holes for blowing up the central part of the wafer and a second group of ventilation holes for blowing up the peripheral part of the wafer, and When the wafer is brought into close contact with the mask. A blow-up close contact operation is performed through the fourth vent group. A contact exposure method characterized in that priority is given to a blow-up contact operation performed through the second vent group.