JP2000084845A - Wafer chuck table - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wafer chuck table capable of reducing inertia while its strength is ensured. SOLUTION: Ribs 24 are radially formed on the back of a table body 12 formed in disk-like manner. Thus, the strength of the table body can be maintained even when the table body 12 itself is thinly formed. Further, the volume of the outer peripheral part of the table body 12 can thus be cut, and inertia can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer chuck table, and more particularly to a wafer chuck table for holding a wafer by vacuum suction.

[0002]

2. Description of the Related Art Wafers such as silicon, which are used as materials for semiconductor devices, tend to have a larger diameter year by year. Accordingly, the size of a wafer chuck table such as a wafer chamfering apparatus tends to be increased.

[0003]

However, the conventional wafer chuck table merely responds to an increase in the diameter of a wafer by simply increasing the diameter of a conventional wafer chuck table. For this reason,
There is a drawback that a prime mover having a large output is required due to an increase in inertia due to an increase in size. Further, with the increase in size, there are also disadvantages that the wafer cannot be completely sucked or the table balance deteriorates.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a wafer chuck table capable of reducing the inertia while securing the strength.

[0005]

In order to achieve the above object, the present invention provides a wafer chuck table for holding a wafer by suction, wherein the table body is formed in a disk shape, and is formed on a surface of the table body. Air suction grooves, ribs radially formed on the back surface of the table body, air flow paths formed along the ribs, and communication holes communicating the air flow paths and the air suction grooves, And suctioning and holding the wafer placed on the table main body by sucking air from the air flow path.

According to the present invention, since the ribs are formed radially on the back surface of the table body, the strength can be secured even if the table body itself is formed thin. In addition, this makes it possible to reduce the inertia and drive the motor with a small output.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a wafer chuck table according to the present invention will be described below in detail with reference to the accompanying drawings. 1 and 2 are a front view and a plan view, respectively, showing a configuration of a wafer chamfering apparatus to which a wafer chuck table according to the present invention is applied.

[0008] As shown in FIG.
0 is the wafer feed unit 50A and the grinding unit 50
B. First, the configuration of the wafer transfer unit 50A will be described. As shown in FIG. 1, a pair of Y-axis guide rails 52 are laid at predetermined intervals on a base plate 51 disposed horizontally. A Y-axis table 56 is slidably supported on the pair of Y-axis guide rails 52 via Y-axis linear guides 54, 54,.

The nut member 5 is provided on the lower surface of the Y-axis table 56.
The nut member 58 is fixed to the pair of Y members.
It is screwed into a Y-axis ball screw 60 disposed between the axis guide rails 52, 52. Both ends of the Y-axis ball screw 60 are rotatably supported by bearing members 62, 62 disposed on the base plate 51, and one end of the Y-axis ball screw 60 is provided on one of the bearing members 62. Motor 64
Output shafts are connected. The Y-axis ball screw 60 is rotated by driving the Y-axis motor 64. As a result, the Y-axis table 56 is
Slide horizontally along 2.

As shown in FIGS. 1 and 2, the Y-axis table 56 has a pair of Y-axis guide rails 52,
2 and a pair of X-axis guide rails 66
Is laid. This pair of X-axis guide rails 66,
On X 66, X-axis linear guides 68, 68,.
A shaft table 70 is slidably supported. A nut member 72 is fixed to the lower surface of the X-axis table 70, and the nut member 72 is attached to the pair of X-axis guide rails 6.
It is screwed to an X-axis ball screw 74 disposed between the first and second X-ray balls 6 and 66. Both ends of the X-axis ball screw 74 have the X
It is rotatably supported by bearing members 76, 76 disposed on a shaft table 70, and one end thereof is connected to an output shaft of an X-axis motor 78 provided on one bearing member 76. . The X-axis ball screw 74 is rotated by driving the X-axis motor 78. As a result, the X-axis table 70 slides horizontally along the X-axis guide rails 66.

As shown in FIGS. 1 and 2, a Z-axis base 80 is vertically provided on the X-axis table 70, and a pair of Z-axis guide rails 8 are provided on the Z-axis base 80.
2, 82 are laid at predetermined intervals. A Z-axis table 86 is slidably supported on the pair of Z-axis guide rails 82 via Z-axis linear guides 84, 84.

A nut member 8 is provided on the side of the Z-axis table 86.
The nut member 88 is fixed to the pair of Zs.
It is screwed into a Z-axis ball screw 90 provided between the axis guide rails 82,82. The Z-axis ball screw 90 has a bearing member 9 whose both ends are disposed on the Z-axis base 80.
2, 92, the lower end of which is connected to the output shaft of a Z-axis motor 94 provided on the lower bearing member 92. The Z-axis ball screw 90 is rotated by driving the Z-axis motor 94. As a result, the Z-axis table 86 slides vertically along the Z-axis guide rails 82.

On the Z-axis table 86, a θ-axis motor 9 is provided.
6 are installed vertically. The θ-axis shaft 98 is connected to the output shaft of the θ-axis motor 96, and the wafer chuck table 10 is horizontally connected to the upper end of the θ-axis shaft 98. The wafer W to be chamfered is
The wafer is placed on the wafer chuck table 10 and held by vacuum suction. The configuration of the wafer chuck table 10 will be described later in detail.

In the wafer feeding unit 50A configured as described above, the wafer chuck table 10
Moves horizontally in the Y direction in the figure by driving the Y-axis motor 64, and horizontally moves in the X direction in the figure by driving the X-axis motor 78. Then, by driving the Z-axis motor 94, it moves vertically in the Z direction in the drawing,
6 is rotated around the θ axis.

Next, the configuration of the grinding unit 50B will be described. As shown in FIGS. 1 and 2, a gantry 102 is installed vertically on the base plate 51. An outer peripheral motor 104 is installed vertically on the gantry 102, and an outer peripheral spindle 106 is connected to an output shaft of the outer peripheral motor 104. The outer peripheral grinding wheel 108 for chamfering the peripheral edge of the wafer W
6 and is rotated by driving the outer peripheral motor 104.

Here, a V-shaped grinding groove 110 having the same chamfering shape required for the wafer W is formed on the outer periphery of the outer peripheral grinding wheel 108 (form-shaped grinding wheel).
By contacting the peripheral edge of the wafer W with the peripheral edge of the wafer W, the peripheral edge of the wafer W is chamfered. In the wafer chamfering apparatus 50 configured as described above, the wafer W is chamfered as follows.

First, the wafer W is placed on the wafer chuck table 10 and held by suction. Next, the outer peripheral motor 104 and the θ-axis motor 96 are driven to rotate the outer peripheral grinding wheel 108 and the wafer chuck table 10 together in the same direction at a high speed. Next, the Y-axis motor 64 is driven to send the wafer W toward the outer peripheral grinding wheel 108. The wafer W sent to the outer peripheral grinding wheel 108 is decelerated just before its outer peripheral portion comes into contact with the grinding groove 110 of the outer peripheral grinding wheel 108, and then slowly sent toward the outer peripheral grinding wheel 108. As a result, the outer peripheral portion of the wafer W is ground by a small amount on the outer peripheral grinding wheel 108 to be chamfered.

As described above, the above-described wafer chamfering apparatus 5
In the case of 0, the peripheral edge of the wafer W rotating at a high speed is brought into contact with the peripheral grinding wheel 108 rotating at a high speed, and the wafer W is chamfered by approaching by a small amount. Next, the configuration of the wafer chuck table 10 according to the present invention applied to the wafer chamfering apparatus 50 will be described.

FIG. 3 is a plan view showing the configuration of the wafer chuck table 10 according to the present embodiment. Also, FIG.
5 is a cross-sectional view taken along line XX and YY of FIG. 3, and FIG. 6 is a cross-sectional view taken along ZZ of FIG. As shown in FIG. 3, annular air suction grooves 14, 14,... Are formed at a constant pitch on the surface of the table body 12 formed in a disk shape. Also, on the surface of the table body 12, linear air suction grooves 16, 16,... Are formed radially. Both are communicated with each other at the intersection.

Further, on the surface of the table body 12,
An annular open-to-atmosphere groove 18 is formed in the outer peripheral portion. Are open at equal intervals in the open-to-atmosphere groove 18, and the open-to-atmosphere holes 20, 20,. On the other hand, as shown in FIGS. 4 and 6, a circular connecting portion 22 is formed at the center of the back surface of the table body 12 so as to protrude.
Then, the ribs 24, 24,
... are formed. The ribs 24 are connected to an annular outer peripheral edge 26 formed along the outer periphery of the table body 12, and the outer peripheral edge 26 is connected to the ribs 24, 24,.
And the same height as the connecting portion 22.

The connecting portion 22 is connected to a θ-axis shaft 98. The connection portion 22 has an air suction hole 28 formed along the axis. The air suction hole 28 is formed to penetrate to the surface of the table main body 12, and the linear air suction groove 1 formed in the surface of the table main body 12 is formed.
6, 16, ... are communicated. Further, when the connecting portion 22 is connected to the θ-axis shaft 98,
Vacuum line 1 formed on the θ-axis shaft 98
00 is communicated.

Each of the ribs 24, 24,... Has a linear groove 30, 30,.
The straight grooves 30, 30,...
Is communicated with the air suction hole 28 formed in the hole. Also,
Each of the straight grooves 30, 30,... Has three communication holes 32, 32, 32 formed along the axis of the table main body 12, and the communication holes 32, 32, 32 12, air suction grooves 16, 1 formed on the surface
6, ... Further, an annular groove 34 is formed in the connecting portion 22, and each of the straight grooves 30, 3 is formed.
Are connected to each other by the annular groove 34.

The outer peripheral edge 26 is formed with a predetermined thickness.
6, 36,... Are formed. The table body 12 is configured as described above. Then, as shown in FIG. 7, a back cover 38 is adhered to the back surface of the table main body 12 to form the wafer chuck table 10.

The back cover 38 is formed in a ring shape, and has an inner diameter substantially equal to the outer diameter of the θ-axis shaft 98. The back cover 38 is adhered to the back surface of the table main body 12 so that the annular groove 3 formed in the connecting portion 22 and the rib 24 is formed as shown in FIG.
4 and the upper portions of the linear grooves 30, 30,... Are closed to form an air flow path.

Air vent holes 40, 40,... Are formed at equal intervals in the outer periphery of the back cover 38, and are adhered to the back surface of the table body 12 so as to be attached to the table body 12. Are communicated with the formed atmosphere opening holes 20, 20,.... The wafer chuck table 10 configured as described above is connected to the top of the θ-axis shaft 98.
Connection is 3 bolts (hexagon socket head bolt) 42, 42,
42. For this reason, three insertion holes 44, 44,... Are formed concentrically at the center of the table body 12, and the θ-axis shaft 98
Are formed with three bolt holes 99, 99, 99 at the top.

At the time of this connection, the θ-axis shaft 9
A V-ring 46 is interposed at the joint between the wafer chuck table 8 and the wafer chuck table 10, and the joint is sealed by the V-ring 46. The operation of the wafer chuck table 10 according to the present embodiment configured as described above is as follows.

When mounting the wafer chuck table 10 on the θ-axis shaft 98, first, balance adjustment is performed. This balance adjustment is performed by tap holes 36, 36 formed on the outer peripheral surface of the wafer chuck table 10.
Adjust the balance weight (set screw) by screwing it in. Then, the balanced wafer chuck table 10 is mounted on the θ-axis shaft 98. The wafer chuck table 10 mounted on the θ-axis shaft 98
An air suction hole 28 formed at the center thereof communicates with a vacuum line 100 formed on the θ-axis shaft 98.

The wafer chuck table 10 mounted on the θ-axis shaft 98 as described above sucks and holds the wafer W as follows. First, the wafer W is placed on the wafer chuck table 10. As a result, the upper portions of the air suction grooves 14 and 16 formed on the surface of the wafer chuck table 10 are closed by the wafer W. As a result, all the systems leading to the vacuum line 100 are sealed. When a vacuum pump (not shown) connected to the vacuum line 100 is driven in this state, the space formed between the wafer W and the air suction grooves 14 and 16 is brought into a vacuum state.
Is held by suction on the wafer chuck table 10.

To release the suction of the wafer W, the operation of the vacuum pump is stopped. Thereby, the vacuum state between the wafer W and the air suction grooves 14, 16 is released,
The suction of the wafer W is released. The open-to-atmosphere groove 18 formed on the outermost surface of the wafer chuck table 10 operates as follows.

When holding the wafer W by suction, the wafer W
Is not perfectly attracted to the table surface, air is sucked in from a gap formed in the outer peripheral portion of the wafer chuck table 10, whereby a situation occurs in which coolant and sludge are sucked into the table. However, the wafer chuck table 1 of the present embodiment
If there is the open-to-atmosphere groove 18 and the open-to-atmosphere holes 20 and 40 as shown in FIG. Since the flow of the air is larger than the flow of the air sucked from the outer peripheral portion of the wafer chuck table 10, almost no air is sucked from the outer peripheral portion. As a result, coolant and the like do not enter from the outer peripheral portion of the wafer chuck table 10, and clogging of the groove by the coolant and the like can be effectively prevented.

Since the air opening holes 20 and 40 are formed downward, even if air flows, coolant or the like is hardly sucked. According to the wafer chuck table 10 configured as described above, since the table body 12 is reinforced by the ribs 22, 22,..., It can be formed as thin as possible while securing the strength as a whole. Thus, the volume of the outer peripheral portion of the table main body 12 can be reduced, and the inertia can be reduced. In addition, by reducing the inertia in this manner, the θ-axis motor 96 for rotating and driving the wafer chuck table 10 can be small in size and small in capacity. Furthermore, by reducing the volume of the table main body 12, material costs can be reduced, and production costs can be suppressed.

In the wafer chuck table 10 of the present embodiment, as shown in FIG.
It is formed so that its thickness becomes thinner from the center toward the outer periphery. Thereby, the inertia can be reduced more effectively. Further, in the wafer chuck table 10 of the present embodiment, tapped holes 36, 36,... Are formed in the outer peripheral portion, and by attaching a balance weight to these tapped holes 36, 36,. Adjustments can be made. In the wafer chuck table 10 thus balanced, no vibration is generated even when the wafer chuck table 10 is rotated at a high speed, and high-precision processing can be performed.

In the wafer chuck table 10 of the present embodiment, linear grooves 30, 30,... Are formed in the ribs 24 of the table main body 12, and closed by a back cover 38 to form an air flow path. However, the method for forming the air flow path is not limited to this. For example, a lateral hole may be formed along the rib 24 with a drill or the like from the outer peripheral portion of the table body 12 to communicate with the air suction hole 28, and then the outer peripheral portion may be sealed to form an air flow path. . in this case,
The use of the back cover 38 becomes unnecessary.

However, when the air flow path is formed by this method, there is a disadvantage that the processing becomes difficult with the wafer chuck table 10 having a large diameter. That is, as the diameter of the wafer chuck table 10 increases, the length of the lateral hole to be drilled also increases, making processing difficult. On the other hand, in the method of the embodiment described above, the table body 12
Since only the linear groove 30 is formed in the rib 24, the processing can be easily performed, and the processing cost can be suppressed.

The shape of the back cover 38 is not limited to a circle, but may be a shape that matches the shape of the connecting portion 22, the rib 24, and the outer peripheral edge 26 projecting from the back surface of the table body 12. By forming a disk shape like the back cover 38 of the present embodiment and covering the entire lower surface of the table main body 12, unevenness on the back surface of the table main body 12 is eliminated, and generation of wind at the time of high-speed rotation can be prevented. The effect that it becomes possible can be obtained. This also has the effect of suppressing the generation of mist.

[0036]

As described above, according to the present invention,
With ribs formed radially on the back of the table body,
Inertia can be reduced while ensuring strength. As a result, the wafer chuck table can be driven to rotate by a motor having a small output.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing a configuration of a wafer chamfering apparatus.

FIG. 2 is a plan view showing a configuration of a wafer chamfering apparatus.

FIG. 3 is a plan view showing a configuration of a wafer chuck table.

FIG. 4 is a sectional view taken along line XX of FIG. 3;

FIG. 5 is a sectional view taken along line YY of FIG. 3;

FIG. 6 is a sectional view taken along the line ZZ of FIG. 4;

FIG. 7 is an assembly diagram of a wafer chuck table.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Wafer chuck table 12 ... Table main body 14, 16 ... Air suction groove 22 ... Connection part 24 ... Rib 26 ... Outer peripheral edge 28 ... Air suction hole 30 ... Straight groove 32 ... Communication hole 34 ... Annular groove 36 ... Tap hole 38 ... Back cover 98 ... θ axis shaft

Claims (4)

[Claims] 1. A wafer chuck table for holding a wafer by suction, wherein a table body formed in a disk shape, an air suction groove formed on a surface of the table body, and a radially formed back surface of the table body. A rib, an air flow path formed along the rib, a communication hole communicating the air flow path and the air suction groove,
A wafer chuck table, wherein air is sucked from the air flow path to suck and hold a wafer placed on the table main body. 2. The wafer chuck table according to claim 1, wherein the air flow path is formed by forming a groove in the rib and covering an upper portion of the groove with a lid member to seal the groove. 3. A balance weight mounting hole is formed at a constant pitch on an outer peripheral surface of the table main body, and a balance weight is mounted on the balance weight mounting hole to perform balance adjustment of the wafer chuck table. Item 3. The wafer chuck table according to item 1 or 2. 4. The wafer chuck table according to claim 1, wherein the thickness of the table body is reduced from a central portion toward an outer peripheral portion.