JP3132029B2 - Wafer bonding equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer bonding apparatus for bonding two wafers in a vacuum.

[0002]

2. Description of the Related Art One example of manufacturing an SOI wafer is a wafer bonding method. In the wafer bonding method,
When bonding wafers together, the bonding is performed such that air bubbles such as air do not enter between the bonded wafers. Therefore, the attachment of the wafer is performed in a vacuum. As an example of the apparatus, there is a wafer bonding apparatus 31 shown in FIG. As shown in the figure, a first wafer chuck 34 is fixedly provided at the bottom inside a vacuum chamber 33 to which a first vacuum pump 32 is connected. This first wafer chuck 34
Is a normal vacuum suction chuck having a wafer holding surface 35 having a convex spherical surface. A drive unit 36 having a feed screw mechanism is provided at the bottom inside the vacuum chamber 33. The driving unit 36 is provided with a second wafer chuck 38 having a wafer holding surface 37 opposing the wafer holding surface 35 of the first wafer chuck 34. The second wafer chuck 38 is formed of a vacuum suction chuck, like the first wafer chuck 34. The wafer holding surface 37 has a convex spherical surface. Further, each of the first and second wafer chucks 34, 3
A second vacuum pump 40 is connected to 8 via a pipe 39.

Next, a method for bonding the first wafer 51 and the second wafer 52 using the wafer bonding apparatus 31 will be described. First, the second vacuum pump 40 is operated,
The first and second wafers 51 and 52 are sucked by setting the respective wafer holding surfaces 35 and 37 to a negative pressure. At this time, the wafer is suctioned in a high vacuum (for example, about 0.01 Pa). Subsequently, the air inside the vacuum chamber 33 is evacuated by the first vacuum pump 32 to make the inside of the vacuum chamber 33 a pressure higher than the wafer suction pressure (for example, about 100 Pa). Next, the second wafer chuck 38 is moved in the direction of the first wafer chuck 34 by the drive unit 36, and the first and second wafers 51,
52 is pressed in a state in which the central portion is in contact. At the same time as the contact, the suction of the first and second wafers 51 and 52 is released, and the first and second wafers 51 and 52 are bonded together by a restoring force due to elasticity. At this time, the first and second wafers 51 and 5
A hydrogen bond acts between the two to bond the first and second wafers 51 and 52 together.

[0004]

However, when wafers are bonded using the above-described wafer bonding apparatus, air does not exist between the bonded wafers because the inside of the vacuum chamber is not at a high vacuum. Then, at the time of bonding, the air enters between the wafers. For this reason, since air is present inside the bonded wafers, for example, when heat treatment is performed on the bonded wafers, the air that has entered between the wafers expands, causing distortion in the wafers. Or damages such as cracks occur.

[0005] The present invention has been made to solve the above-mentioned problems, and has as its object to provide a wafer bonding apparatus for manufacturing a bonded wafer having excellent quality.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object. That is, inside a vacuum chamber connected to a vacuum pump, a first wafer chuck having a wafer holding surface that generates static electricity, and a second wafer chuck having a wafer holding surface that faces the wafer holding surface of the first wafer chuck and generates static electricity. And two wafer chucks. A power supply for generating static electricity is connected to the wafer holding surfaces of the first and second wafer chucks. Further, one or both of the first and second wafer chucks may have the first and second wafer chucks.
A drive unit is provided for moving the first and second wafer chucks in the direction of the wafer chuck.

[0007]

The wafer bonding apparatus having the above-described structure generates static electricity on the wafer holding surface of the wafer chuck and attracts the wafer to the wafer holding surface. It does not come off from the holding surface. Therefore, air does not enter between the bonded wafers.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the schematic sectional view of FIG. As shown in the figure, a vacuum pump 12 for exhausting air inside the vacuum chamber 11 is connected to a vacuum chamber 11 formed of a sealed container.

A first wafer chuck 13 is fixedly provided inside the vacuum chamber 11 at the bottom thereof. The first wafer chuck 13 has a wafer holding surface 14 that generates static electricity. The wafer holding surface 14 is formed as a convex spherical surface having a radius of curvature of, for example, 20 m. A drive unit 15 is provided inside the vacuum chamber 11 at the bottom thereof. The drive unit 15 includes a motor 17 connected to a power supply 16, a feed screw 18 formed on a rotation shaft of the motor 17, and a female screw that meshes with the feed screw 18. The receiving portion 19 is movable in 13 directions. The second wafer chuck 20 is provided on the upper surface of the receiving portion 19 with the wafer holding surface 21 of the second wafer chuck 20 facing the wafer holding surface 14 of the first wafer chuck 13. The wafer holding surface 21 generates static electricity similarly to the wafer holding surface 14, and is formed as a convex spherical surface having a curvature radius of, for example, 20 m.

As described above, since the second wafer chuck 20 is attached to the drive unit 15, the second wafer chuck 20
Becomes movable in the direction of arrow A. Further, a static electricity generating power supply 22 is connected to the first wafer chuck 13 and the second wafer chuck 20. By this static electricity generating power supply 22, electric charges are stored in the first and second wafer chucks 13 and 20, and static electricity is generated on each of the wafer holding surfaces 14 and 21.

Next, a method of bonding the first wafer 51 and the second wafer 52 by using the wafer bonding apparatus 1 having the above configuration will be described. First, the wafer holding surface 1 of the first and second wafer chucks 13 and 20 is supplied by the static electricity generating power supply 22.
4 and 21 to generate static electricity, so that each of the first and second wafers 5
1 and 52 are attracted to the respective wafer holding surfaces 14 and 21 by electrostatic force. Subsequently, the air inside the vacuum chamber 11 is evacuated by the vacuum pump 12, and the pressure inside the vacuum chamber 11 is reduced to, for example, 0.01 Pa or less.

Next, the motor 17 of the drive unit 15 is driven to rotate the feed screw 18. Then, the receiving portion 19 engaged with the feed screw 18 is moved in the direction of the first wafer chuck 13 and pressed while the central portions of the first and second wafers 51 and 52 are in contact with each other. At the same time as the contact, each first and second wafer 5
1 and 52 are released, and the first and second wafers 51 and 5 are released.
2 are bonded by the restoring force due to the elasticity of 2. At this time, a hydrogen bond acts between the first and second wafers 51 and 52, and the first and second wafers 51 and 52 are integrally bonded without air entering between the first and second wafers 51 and 52. . The bonded wafer is the first wafer chuck 13 and the second wafer chuck 13.
Since it is pressed by the wafer chuck 20, it does not fall from the first and second wafer chucks 13 and 20.

In the above embodiment, the first wafer chuck 13
Although the wafer holding surface 14 is formed as a convex spherical surface, it may be formed as a flat surface. In this case, the first and second wafers 51,
Simultaneously with the contact of the second wafer holding surface 52, the suction by the electrostatic force on the second wafer holding surface 21 side is released, and the first and second wafers 51, 51 and The bonding of 52 is performed. Alternatively, conversely, the wafer holding surface 21 of the second wafer chuck 20 is formed to be flat, and simultaneously with the contact with the first and second wafers 51 and 52, the electrostatic charge on the wafer holding surface 14 side of the first wafer chuck 13 Adsorption by force may be released.

[0014]

As described above, according to the present invention,
Since the wafer is stuck to the wafer holding surface by using static electricity and bonded to the wafer, the inside of the vacuum chamber can be made ultra-high vacuum. For this reason, since air does not enter between the bonded wafers, it becomes possible to manufacture a bonded wafer having excellent electrical properties.

[Brief description of the drawings]

FIG. 1 is a schematic configuration sectional view of an embodiment.

FIG. 2 is a schematic cross-sectional view of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wafer bonding apparatus 11 Vacuum chamber 12 Vacuum pump 13 First wafer chuck 14 Wafer holding surface 15 Drive unit 20 Second wafer chuck 21 Wafer holding surface 22 Static electricity generation power supply

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/02 H01L 21/68 H01L 27/12

Claims (1)

(57) [Claims] A vacuum chamber to which a vacuum pump is connected;
A first wafer chuck provided inside the vacuum chamber and having a wafer holding surface for generating static electricity; and a first wafer chuck provided inside the vacuum chamber for generating static electricity and the first wafer. A second wafer chuck having a wafer holding surface opposed to the wafer holding surface of the chuck, an electrostatic power supply connected to the first wafer chuck and the second wafer chuck, the first wafer chuck or the second wafer The first and second wafer chucks are provided on one or both of the chucks, and the first and second wafer chucks are provided with the first
A wafer bonding apparatus comprising a wafer chuck or a drive unit for moving the second wafer chuck.