JPS6233182B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a wafer chuck used for handling semiconductor wafers in the manufacturing process of semiconductor devices.

When manufacturing semiconductor devices such as ICs, handling of semiconductor wafers in the wafer process is an important issue that affects manufacturing yield. It is important to handle it so as not to contaminate or damage the surface on which the transistor elements are formed, and for this purpose, a vacuum chuck has traditionally been used, and this vacuum chuck is called a wafer chuck. ing. The wafer chuck chucks the wafer by vacuum suction from the back side.
It is a jig that moves or fixes the resist, and is widely used in spinners and spin dryers that apply resist, alignment devices, and other manufacturing machines.

However, such wafer chucks are designed to prevent damage or deformation of the wafer.
A wafer chuck with a soft touch is preferable.

[Prior Art] Now, with the development of semiconductor devices such as ICs, semiconductor wafers have gradually become larger in diameter, and wafers that used to be 3 to 4 inches in diameter have now grown to 6 or 8 inches in diameter. It has been.

Figure 3 shows a recent wafer chuck for chucking such large wafers.
Figure a is a sectional view, figure b is a plan view seen from the chucking surface, and figure a shows the AA' cross section of figure b.

As shown in the figure, a vacuum suction port 1 is provided at the center of the chucking surface, and a plurality of radial grooves 2 (four in the figure) on all sides and a plurality of ring grooves 3 communicating with these grooves are formed on the entire surface of the chucking surface. has been done. For example, a wafer chuck for chucking 6-inch wafers has a chucking surface with a diameter of 150 mm, and 10 to 12 ring grooves 3 with a groove width of 1 mm are provided on the chucking surface, and the wafer chuck is sucked at a reduced pressure of about 200 Torr to chuck the wafer. is adsorbed. In FIG. 3a, the suction wafer 10 is also shown.

In the past, when the wafer diameter was small, wafers were held with a wafer chuck that simply had a vacuum suction port in the center, but as wafers have become larger in diameter, it has become difficult to hold them with just that. Wafer chucks that also have a groove leading to a vacuum suction port have come into use.

[Problems to be Solved by the Invention] However, the chucking method in which the wafer is vacuum-chucking using a wafer chuck has the problem that the wafer is deformed or even cracked because the wafer is sucked with a strong suction force. arise. In addition, when using the vacuum chuck method, chemicals or water may flow back into the vacuum source when processing chemicals or washing with water.
In addition, mist flows into the vacuum source,
There is a risk of contaminating the wafer.

To avoid this, a Bernoulli type wafer chuck as shown in FIG. 4 has recently been devised. In this method, on the contrary, a gas injection port 4 is provided at the center of the chucking surface, and high-pressure gas is applied around the wafer 10. In this case, gas is ejected from around the wafer, creating a negative pressure between the chuck and the wafer, which causes the wafer to be drawn toward the chuck.

According to this Bernoulli type wafer chuck, the problem of wafer deformation and cracking due to chucking is reduced, and there is no need to worry about backflow of chemicals or water. However, since the wafer is held in a floating state, the wafer becomes unstable. Moreover, since the wafer is not chucked reliably, rotation cannot be given to the wafer. Wafer rotation is a method conventionally used to uniformly process resist coating and etching. Therefore, wafer chucks of this type have not yet been widely used.

The present invention solves these problems and proposes a wafer chuck that chucks reliably and does not cause deformation or cracking.

[Means for solving the problem] The purpose is to have a suction surface with a smaller area than the wafer to be suctioned, and to provide radial grooves on the suction surface.
Further, a portion of the circumferential surface of the suction surface facing the wafer to be sucked is made concave, a plurality of gas injection ports are provided in the concave portion, and gas is injected from the gas injection ports in the direction of the wafer periphery. This is accomplished by using a wafer chuck that attracts the wafer to its surface.

[Function] That is, the present invention is a wafer chuck in which gas is injected around the chuck surface to perform a so-called aspirator function, thereby sucking a wafer.

By doing so, you will be able to obtain appropriate suction power, and also be able to chuck softly and reliably.
There is no deformation or cracking of the wafer, and it is also possible to rotate the wafer.

[Examples] Hereinafter, examples will be described in detail with reference to the drawings.

FIG. 1 shows a wafer chuck according to the present invention, in which FIG. 1A is a sectional view, FIG. 1B is a plan view from the chuck surface, and FIG.

In FIG. 1a, the suction wafer 10 is shown at the same time, and as shown in the figure, approximately 4 kg/cm ² of gas is injected from the gas inlet 12 provided on the back side of the chucking surface 11, and the area around the chucking surface is Gas is injected from a large number of gas injection ports 13. Gas injection port 13
The gas is injected toward the circumferential edge of the wafer, and as a result, the aspirator function works and the space between the wafer 10 and the chucking surface 11 flows out toward the circumferential surface of the wafer, and the chucking surface and Negative pressure is created between the wafer and the wafer, and the wafer is chucked onto the chucking surface.

Even after chucking, air continues to flow out in the circumferential direction of the wafer from the radial grooves 14 provided on the chucking surface and the concentric ring grooves 15 communicating with the radial grooves 14, thereby maintaining negative pressure and maintaining the chucking of the wafer.

In terms of dimensions, for example, in a wafer chuck for chucking 6-inch (150 mmφ) wafers, a 10 mm recess 16 is provided around the chuck surface with a diameter of 120 mmφ, and 70 to 80 recesses are formed in that area. A gas injection port 13 is provided. FIG. 2 shows a partial sectional view of the same (the figure shows a state in which the wafer 10 is being attracted), and the gas injection port 12 has a diameter of 1.2 mmφ and a recess height L of 0.7 to 1 mm. Similarly, the depth of the grooves 14 and 15 on the chucking surface 11 is approximately 0.7 to 1 mm, and the groove width is approximately 1 mm. These dimensions vary somewhat depending on the wafer diameter and pressurizing conditions.

If such a wafer chuck according to the present invention is used, the chuck will be softer than a vacuum suction chuck, and there will be no contamination of the wafer due to backflow of solution or mist. Furthermore, rotation of the wafer is also possible. Moreover, if nitrogen gas is used as the pressurized gas, nitrogen gas is commonly used in wafer processing chambers, and there is an advantage that a vacuum source or vacuum piping for a conventional vacuum suction chuck is not required.

[Effects of the Invention] As is clear from the above description, according to the wafer chuck of the present invention, the wafer can be chucked without deformation, and the yield of ICs can be improved.
This greatly contributes to higher quality.

[Brief explanation of the drawing]

1a and b are a sectional view and a plan view of a wafer chuck according to the present invention, FIG. 2 is a partial sectional view thereof,
3a and 3b are a sectional view and a plan view of a conventional wafer chuck, and FIG. 4 is a sectional view of another example of the conventional wafer chuck. In the figure, 10 is a wafer, 11 is a chucking surface, 12 is a gas inlet, 13 is a gas injection port,
14 is a radial groove, 15 is a ring groove, and 16 is a recess.

Claims (1)

[Claims] 1. The suction surface 11 has a smaller area than the suction target wafer 10, the suction surface 11 is provided with radial grooves 14, and the portion around the suction surface 11 facing the suction target wafer 10 is made concave, A wafer chuck characterized in that a plurality of gas injection ports 13 are provided in the concave portion 16, and gas is ejected from the gas injection ports 13 in the direction of the wafer periphery to attract the wafer 10 to the suction surface 11.