JPH0682751B2 - Wafer check - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a wafer chuck for sucking and holding a semiconductor wafer to be exposed through a mask in a contact exposure type semiconductor exposure apparatus.

BACKGROUND OF THE INVENTION In the lithographic process of a semiconductor manufacturing process,
A semiconductor wafer coated with a resist is exposed through a mask or a reticle to transfer a pattern. As such a pattern transfer exposure method, a contact method, a proximity method, a reflection type projection method, a reduction lens projection method and the like are used. In the contact method, a mask and a wafer are brought into close contact with each other to perform exposure, so that a relatively high-resolution pattern can be obtained. In such a contact exposure type semiconductor exposure apparatus, a wafer is adsorbed and held by a vacuum chuck, and a mask is aligned and mounted thereon. In this case, if a gas is sealed between the mask and the wafer, a high resolution pattern cannot be obtained due to light diffraction or the like. Therefore, in order to obtain a high resolution pattern, it is necessary to prevent the gas trap and ensure the close contact between the mask and the wafer, and the mask must be precisely aligned with the wafer.

[Prior Art] A conventional wafer chuck of a semiconductor exposure apparatus is, for example, an actual wafer chuck.
No. 54-54270. In this known wafer chuck, since radial grooves are formed on the upper surface of the wafer mounting holder over the wiping area until reaching the outer peripheral end, when a vacuum pressure is applied to these grooves, the wafer is largely deformed. However, there is a problem in that the distortion of the pattern due to the deformation of the wafer during baking becomes large, and the accuracy of the alignment between the mask and the wafer decreases due to the deformation of the wafer, which is a problem in practical use.

[Object of the Invention] The present invention has been made in view of the above-mentioned drawbacks of the prior art, and reduces the amount of wafer deformation during vacuum suction to suppress pattern distortion and improve the alignment accuracy between the mask and the wafer. An object of the present invention is to provide a wafer chuck that enables pattern printing with high resolution and high accuracy.

In order to achieve this object, the wafer chuck of the present invention,
A groove for holding a wafer is provided on the upper surface of the wafer mounting table, and a radial groove extending from the vicinity of the center of the upper surface of the wafer mounting table to the vicinity of the inside of the outer peripheral edge is provided in a state of being separated from the groove for holding the wafer. The wafer holding groove and the radial groove communicate with different vacuum control means.

[Embodiment] FIG. 1 is a top view of a wafer chuck according to the present invention.
FIG. 2 is a vertical sectional view taken along the line II-C-II. A plurality of concentric grooves 3 and two radial grooves 2 extending from the vicinity of the center to the inside of the outer peripheral edge are formed on the upper surface of the wafer mounting table 20 that constitutes the wafer chuck 1.
The two radial grooves 2 are formed symmetrically with respect to the center C. Each radial groove 2 communicates with a vacuum source (not shown) through a conduction hole 4. Further, each of the concentric grooves 3 communicates with a vacuum source (not shown) via a conduction hole 14. Through hole
4 and 14 can be connected to each other by switching to a vacuum source or the atmosphere via solenoid valves 8 and 18, respectively. The concentric grooves 3 are for holding the wafer, and the radial grooves 2 are for releasing gas between the wafer and the mask. Each radial groove 2 is provided at a position deviated from the alignment wafer alignment mark 11 and the mask alignment mark 12 when the wafer 5 and the mask 6 are set. A seal rubber 9 is provided on the outer peripheral portion of the wafer mounting table 20, and a vacuum chamber 10 can be formed between the mask holder 7 on which the mask 6 is mounted and the wafer mounting table 20 on which the wafer 5 is mounted.

In the wafer chuck having the above structure, the solenoid valve 8,
When vacuum pressure is applied to the radial grooves 2 and the concentric circular grooves 3 via 18, as shown in FIG. 2, the wafer 5 is appropriately deformed into a concave shape at the radial grooves 2 and the wafer 5 The gas between the mask 6 and the mask 6 is released to prevent generation of a gas trap.
At this time, since the groove width of the concentric groove 3 is small (about 1 mm), the wafer 5 is hardly deformed.

EFFECTS OF THE INVENTION As described above, in the wafer chuck according to the present invention, since the radial grooves are provided on the upper surface of the wafer mounting table from near the center to the inside of the outer peripheral edge, the contact between the wafer and the mask is made. By applying vacuum pressure to these radial grooves, the wafer is appropriately deformed and the gas on the upper surface of the wafer can be discharged uniformly and surely, the adhesion between the mask and the wafer is improved, and the resolution is high and the accuracy is high. High-quality pattern printing becomes possible. Further, since each radial groove is provided at a position deviating from the alignment mark for aligning the mask and the wafer, the positional accuracy is improved without causing a displacement due to the deformation of the wafer during the alignment.

The number of radial grooves 2 is not limited to two. The number and shape of the concentric circular grooves 3 can be appropriately selected so that the wafer can be adsorbed and fixedly held.

[Brief description of drawings]

1 is a top view of a wafer chuck according to the present invention, and FIG. 2 is a sectional view taken along the line II-C-II in FIG. 1: Wafer chuck 2: Radial groove 3: Concentric groove 4,14: Conducting hole 5: Wafer 6: Mask 11: Wafer alignment mark 12: Mask alignment mark 20: Wafer mounting table.

Claims (8)

[Claims] 1. A groove for holding a wafer is provided on an upper surface of a wafer mounting table, and a radial groove extending from the vicinity of the center of the upper surface of the wafer mounting table to the vicinity of the inside of an outer peripheral edge is separated from the groove for holding the wafer. The wafer chuck, wherein the wafer holding groove and the radial groove are connected to different vacuum control means. 2. The wafer chuck according to claim 1, wherein the upper surface of the wafer mount is substantially circular, and the groove for holding the wafer comprises a plurality of concentric grooves. 3. The wafer chuck according to claim 1, wherein the radial groove is provided at a position deviated from the alignment mark between the wafer and the mask. 4. The vacuum control means each have an electromagnetic valve, and each of the wafer holding groove and the radial groove is switched and communicated with a vacuum source or an atmosphere via the electromagnetic valve. The wafer chuck according to any one of claims 1 to 3, wherein: 5. The radial groove has a plurality of grooves symmetrical with respect to the center of the upper surface of the wafer mounting table, as claimed in any one of claims 1 to 4. Wafer chuck. 6. A seal material for sealing between the wafer mounting table and the mask holder is provided on an outer peripheral portion of the wafer mounting table, and a wafer mounting table on which a wafer is mounted and a mask holder on which a mask is mounted are provided. The wafer chuck according to any one of claims 1 to 5, wherein a vacuum chamber can be formed therebetween. 7. The radial groove is a groove for preventing a gas trap that introduces a vacuum pressure to deform the wafer and let out gas on the upper surface of the wafer, thereby preventing gas trapping. The wafer chuck according to claim 1. 8. The wafer holding groove has a groove width narrowed to such an extent that the wafer is not deformed when a vacuum pressure is introduced, according to any one of claims 1 to 7. Wafer chuck described.