JP4092603B2 - Wafer chuck table - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wafer chuck table, and more particularly to a wafer chuck table used in a wafer chamfering apparatus.
[0002]
[Prior art]
A wafer made of silicon or the like as a material of a semiconductor element is sliced from a state of an ingot by a cutting machine such as a wire saw, and then a peripheral portion is chamfered by a wafer chamfering apparatus.
In general, in a wafer chamfering device, the wafer to be chamfered is vacuum-sucked and held by a wafer chuck table, but if the cut surface of the wafer is not good, coolant is sucked from the gap and the vacuum generator etc. breaks down. There is a problem of end. For this reason, a drain separator is usually installed in the middle of the piping connecting the wafer chuck table and the vacuum generator so that coolant does not enter the vacuum generator.
[0003]
[Problems to be solved by the invention]
However, in the past, the coolant accumulated in the drain separator was drained using air for breaking the vacuum. However, since uniform air was flowing on both the wafer chuck table side and the drain separator side, the air was discharged on the drain separator side. The pressure was insufficient, and it took a long time to sufficiently drain the accumulated coolant. On the contrary, the air pressure is too strong on the wafer chuck table side, and there is a problem that the coolant remaining in the vacuum path blows up from the wafer chuck table when the vacuum breaks and the surroundings become dirty. In addition, when a wafer having a small thickness is adsorbed by a wafer chuck table and subjected to vacuum break, there is a problem that the wafer is broken by air pressure.
[0004]
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 that can efficiently drain the coolant accumulated in the drain separator in a short time.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a wafer chuck table that is connected to a vacuum generating means via a drain separator and vacuum-sucks and holds a wafer placed on the upper surface.
An air supply means for supplying vacuum breaking air to the wafer chuck table, connected in the middle of a pipe line connecting the drain separator and the vacuum generating means, and in the pipe line connecting the drain separator and the wafer chuck table The flow rate of the vacuum breaking air is limited by the flow rate regulating valve to a predetermined flow rate by the flow rate regulating valve. The liquid accumulated in the drain separator is drained.
[0006]
According to the present invention, a flow rate adjusting valve is installed between the drain separator and the wafer chuck table, and the flow rate of the vacuum breaking air supplied to the wafer chuck table by the flow rate adjusting valve is limited to a predetermined flow rate. As a result, when air for vacuum breakage is supplied from the air supply means to the wafer chuck table at the time of vacuum break, the flow toward the wafer chuck table is restricted, so that the pressure in the drain separator increases. The liquid accumulated in the drainage is drained vigorously in a short time by the pressure in the drain separator. On the other hand, since weak pressure air is supplied to the wafer chuck table, it is possible to release the adsorption of the wafer without causing the wafer to crack or the like.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of a wafer chuck table according to the present invention will be described in detail with reference to the accompanying drawings.
1 and 2 are a front view and a plan view, respectively, showing the configuration of a wafer chamfering apparatus to which a wafer chuck table according to the present invention is applied.
[0008]
As shown in the figure, the wafer chamfering apparatus 50 includes a wafer feeding unit 50A and a grinding unit 50B.
First, the configuration of the wafer feeding unit 50A will be described. As shown in FIG. 1, a pair of Y-axis guide rails 52, 52 are laid at a predetermined interval on a horizontally disposed base plate 51. A Y-axis table 56 is slidably supported on the pair of Y-axis guide rails 52, 52 via Y-axis linear guides 54, 54,.
[0009]
A nut member 58 is fixed to the lower surface of the Y-axis table 56, and the nut member 58 is screwed to a Y-axis ball screw 60 disposed between the pair of Y-axis guide rails 52, 52. Both ends of the Y-axis ball screw 60 are rotatably supported by bearing members 62 and 62 disposed on the base plate 51, and one end thereof has a Y-axis provided on one bearing member 62. The output shaft of the motor 64 is connected. The Y-axis ball screw 60 is rotated by driving the Y-axis motor 64, and as a result, the Y-axis table 56 slides horizontally along the Y-axis guide rails 52 and 52.
[0010]
As shown in FIGS. 1 and 2, a pair of X-axis guide rails 66, 66 are laid on the Y-axis table 56 so as to be orthogonal to the pair of Y-axis guide rails 52, 52. An X-axis table 70 is slidably supported on the pair of X-axis guide rails 66, 66 via X-axis linear guides 68, 68,.
A nut member 72 is fixed to the lower surface of the X-axis table 70, and the nut member 72 is screwed to an X-axis ball screw 74 disposed between the pair of X-axis guide rails 66, 66. Both ends of the X-axis ball screw 74 are rotatably supported by bearing members 76, 76 disposed on the X-axis table 70, and one end thereof is provided on one bearing member 76. The output shaft of the X-axis motor 78 is connected. 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, 66.
[0011]
As shown in FIGS. 1 and 2, a Z-axis base 80 is erected vertically on the X-axis table 70, and a pair of Z-axis guide rails 82, 82 are predetermined on the Z-axis base 80. It is laid with the interval of. A Z-axis table 86 is slidably supported on the pair of Z-axis guide rails 82 and 82 via Z-axis linear guides 84 and 84.
[0012]
A nut member 88 is fixed to a side surface of the Z-axis table 86, and the nut member 88 is screwed to a Z-axis ball screw 90 disposed between the pair of Z-axis guide rails 82 and 82. Both ends of the Z-axis ball screw 90 are rotatably supported by bearing members 92 and 92 disposed on the Z-axis base 80, and the lower end of the Z-axis ball screw 90 is provided on the lower bearing member 92. The output shaft of the Z-axis motor 94 is connected. The Z-axis ball screw 90 is rotated by driving the Z-axis motor 94, and as a result, the Z-axis table 86 slides vertically along the Z-axis guide rails 82 and 82.
[0013]
A θ-axis motor 96 is installed vertically on the Z-axis table 86. A 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 portion of the θ-axis shaft 98. The wafer W to be chamfered is placed on the wafer chuck table 10 and held by vacuum suction. The configuration of the wafer chuck table 10 will be described in detail later.
[0014]
In the wafer feed 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 in the X direction in the figure by driving the X axis motor 78. Move horizontally to. The Z-axis motor 94 is driven to move vertically in the Z direction in the figure, and the θ-axis motor 96 is driven to rotate around the θ-axis.
[0015]
Next, the configuration of the grinding unit 50B will be described. As shown in FIGS. 1 and 2, a gantry 102 is vertically installed on the base plate 51. An outer peripheral motor 104 is vertically installed on the gantry 102, and an outer peripheral spindle 106 is connected to the output shaft of the outer peripheral motor 104. An outer peripheral grinding wheel 108 for chamfering the peripheral edge of the wafer W is mounted on the outer peripheral spindle 106 and is rotated by driving the outer peripheral motor 104.
[0016]
Here, a V-shaped grinding groove 110 which is the same as the chamfered shape required for the wafer W is formed on the outer periphery of the outer peripheral grinding stone 108 (total grinding wheel), and the periphery of the wafer W is formed in the groove 110. By abutting, 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.
[0017]
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 both the outer peripheral grinding wheel 108 and the wafer chuck table 10 in the same direction at 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 stone 108 is decelerated immediately before the outer peripheral portion comes into contact with the grinding groove 110 of the outer peripheral grinding stone 108, and then slowly sent toward the outer peripheral grinding stone 108. As a result, the outer peripheral portion of the wafer W is chamfered by being ground by the outer peripheral grinding wheel 108 by a minute amount.
[0018]
In this way, in the wafer chamfering apparatus 50 described above, the peripheral grinding wheel 108 that rotates at high speed is brought into contact with the periphery of the wafer W that rotates at high speed, and chamfering is performed by bringing the wafer W closer to each other by a minute amount.
Next, the configuration of the wafer chuck table 10 applied to the wafer chamfering apparatus 50 will be described.
[0019]
FIG. 3 is a plan view showing the configuration of the wafer chuck table 10. 4 and 5 are an XX sectional view and a YY sectional view of FIG. 3, respectively, and FIG. 6 is a ZZ sectional view 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, and linear air suction grooves 16, 16, ... are formed in a radial pattern, and they are communicated with each other at their intersections.
[0020]
An annular atmosphere opening groove 18 is formed on the outer periphery of the surface of the table body 12. In the air release groove 18, air release holes 20, 20,... Are formed at equal intervals, and the air release holes 20, 20,.
On the other hand, as shown in FIGS. 4 and 6, a circular connecting portion 22 is formed on the back surface of the table body 12 so as to protrude from the center portion. Ribs 24, 24,... Are formed radially from the connecting portion 22. The ribs 24, 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 the same height as the ribs 24, 24,. Is formed.
[0021]
The connecting portion 22 is connected to the θ-axis shaft 98. An air suction hole 28 is formed in the connecting portion 22 along the axis. The air suction holes 28 are formed so as to penetrate to the surface of the table body 12 and communicate with linear air suction grooves 16, 16,... Formed on the surface of the table body 12. The air suction hole 28 communicates with an air flow path 100 formed in the θ-axis shaft 98 when the connecting portion 22 is connected to the θ-axis shaft 98. A vacuum air pipe 120 is connected to the air flow path 100, and the air in the air flow path 100 is sucked from the air pipe 120 to be in a vacuum state. The circuit configuration of the air pipe 120 will be described in detail later.
[0022]
In each of the ribs 24, 24,..., Straight grooves 30, 30,. The linear grooves 30, 30,... Communicate with air suction holes 28 formed in the connecting portion 22. Further, the linear grooves 30, 30,... Are respectively provided with three communication holes 32, 32, 32 along the axis of the table body 12, and the communication holes 32, 32, 32 are formed as described above. The air suction grooves 16, 16,... Formed on the surface of the table body 12 communicate with each other. Further, an annular groove 34 is formed in the connecting portion 22, and the linear grooves 30, 30,... Are communicated with each other by the annular groove 34.
[0023]
The outer peripheral edge 26 is formed with a predetermined thickness, and tap holes 36, 36,... Are formed at a constant pitch on the outer peripheral surface thereof.
The table body 12 is configured as described above. The back cover 38 is bonded to the back surface of the table main body 12 to constitute the wafer chuck table 10.
The back cover 38 is formed in a ring shape, and the inner diameter thereof is substantially the same as the outer diameter of the θ-axis shaft 98. Then, the back cover 38 is adhered to the back surface of the table main body 12, and as shown in FIG. 5, the annular groove 34 formed in the connecting portion 22 and the rib 24 and the straight grooves 30, 30,. The upper part is closed and an air flow path is formed.
[0024]
Further, air release holes 40, 40,... Are formed at equal intervals on the outer periphery of the back cover 38, and are formed on the table body 12 by being bonded to the back surface of the table body 12. Communicating with the air opening holes 20, 20,.
The wafer chuck table 10 configured as described above is connected to the top of the θ-axis shaft 98. The connection is made by three bolts (hexagon socket head bolts) 42, 42, 42. Therefore, three insertion holes 44, 44,... Are formed on the central portion of the table body 12 at equal intervals on a concentric circle, and three bolt holes are formed at the top of the θ-axis shaft 98 so as to correspond thereto. 99, 99, 99 are formed on the concentric circles at equal intervals.
[0025]
In this connection, a V-ring 46 is interposed at the joint between the θ-axis shaft 98 and the wafer chuck table 10, and the joint is sealed by the V-ring 46.
In the wafer chuck table 10 configured as described above, the wafer W is placed on the wafer chuck table 10 and vacuum-adsorbed onto the wafer chuck table 10 by setting the air flow path 100 in a vacuum state.
[0026]
Next, a circuit configuration of the air pipe 120 connected to the wafer chuck table 10 will be described.
FIG. 7 is a conceptual diagram showing a circuit configuration of the air pipe 120. An air pipe 120 connected to the wafer chuck table 10 is connected to a vacuum pump 122. A drain separator 124 is installed in the middle of the air pipe 120.
[0027]
FIG. 9 is a front cross-sectional view showing the configuration of the drain separator 124. As shown in the figure, the drain separator 124 is configured by installing an element 130 in a case 128 connected to a lower portion of a body 126. When the air sucked from the suction port 128A of the body 128 passes through the element 130, the water content is separated and discharged from the discharge port 128B. The separated water is drained from a drain port 128A formed in the lower part of the case 128. Here, a drainage pipe 132 is connected to the drainage port 128 </ b> A of the case 128 as shown in FIG. 7, and a drainage valve 134 is installed in the drainage pipe 132. The moisture in the case 128 is drained from the case 128 by opening the drain valve 134.
[0028]
A vacuum break air supply pipe 138 is connected between the drain separator 124 and the vacuum pump 122 via a vacuum switching valve 136. A compressor (not shown) is connected to the vacuum break air supply pipe 138, and vacuum break air is supplied from the compressor. The vacuum switching valve 136 selectively switches the connection between the compressor and the vacuum pump 122.
[0029]
A pressure switch 140 is installed between the drain separator 124 and the vacuum switching valve 136, and the pressure switch 140 operates when the pressure in the air pipe 120 reaches a predetermined pressure.
Further, a flow rate adjusting valve (flow rate adjusting valve with check valve) 142 is installed between the drain separator 124 and the wafer chuck table 10, and the flow rate adjusting valve 142 only has a flow of air toward the wafer chuck table 10. Is restricted to a constant flow rate (the flow of air from the wafer chuck table 10 to the vacuum pump 122 is allowed to flow freely). Therefore, even if vacuum breaking air is supplied from the compressor at the time of vacuum break, it does not flow much to the wafer table 10 (only vacuum breaking air necessary for releasing the suction of the wafer W flows), and instead the pressure in the air pipe 120 Becomes higher. As a result, the water separated by the drain separator 124 is efficiently drained.
[0030]
The operation of the embodiment of the wafer chuck table 10 according to the present invention configured as described above is as follows.
As shown in FIG. 7, the drain valve 134 is closed in the initial state, and the vacuum switching valve 136 is connected to the vacuum pump 122 side.
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 blocked by the wafer W. As a result, all the paths leading to the vacuum pump 122 are sealed. When the vacuum pump 122 is driven in this state, the space formed between the wafer W and the air suction grooves 14 and 16 is in a vacuum state, whereby the wafer W is sucked and held on the wafer chuck table 10. In this state, chamfering is performed.
[0031]
Here, when the coolant enters from the gap between the held wafers W and is sucked into the air pipe 120, the coolant is separated from the air by the drain separator 124. The separated coolant is stored in the case 128 of the drain separator 124.
When chamfering processing of the wafer W is completed and the suction of the wafer W is released, first, the driving of the vacuum pump 122 is stopped. Next, the drain valve 134 is opened as shown in FIG. As a result, the drain separator 124 and the drain pipe 132 are communicated, and the coolant stored in the drain separator 124 is drained. However, this does not drain smoothly due to natural fall.
[0032]
Subsequently, the connection of the vacuum switching valve 136 is switched to the compressor side. Thereby, the vacuum breaking air is supplied into the air pipe 120.
Here, the vacuum breaking air supplied into the air pipe 120 flows toward the wafer chuck table 10, but since the flow is throttled by the flow rate adjusting valve 142 installed between the drain separator 124, the wafer chuck table. 10 does not flow too much (the amount of air necessary to release the adsorption of the wafer W flows). As a result, the pressure in the air pipe 120 is increased, and the coolant that has been pushed by the increased pressure and accumulated in the case 128 of the drain separator 124 is exhausted vigorously from the drain port 128A.
[0033]
The supply of the vacuum breaking air is continued for a predetermined time, and after the predetermined time has elapsed, the connection of the vacuum switching valve 136 is switched to the vacuum pump 122 side. At the same time, the drain valve 134 is closed.
As described above, according to the wafer chuck table 10 of the present embodiment, the air pressure in the air pipe 120 is increased by restricting the flow of the vacuum breaking air flowing toward the wafer chuck table 10 at the time of the vacuum breaking. The coolant accumulated in the drain separator 124 is drained at once using the pressure. Thereby, the coolant in the drain separator 124 can be drained efficiently in a short time. This also prevents the coolant from remaining in the pipeline. As a result, even if the vacuum break is performed as in the conventional case, the coolant does not blow up from the wafer chuck table 10 and the surroundings are not soiled.
[0034]
Further, by restricting the flow of the vacuum breaking air flowing through the wafer chuck table 10, the adsorption of the wafer W can be released with a weak breaking pressure, and the cracking of the wafer W due to the breaking pressure can be effectively prevented. . Further, it is possible to effectively prevent the wafer W from being greatly displaced from the wafer chuck table 10 by the breakdown pressure.
[0035]
In the present embodiment, the vacuum pump 122 is used as the vacuum generating means, but the vacuum generating means is not limited to this, and for example, a vacuum ejector may be used.
In this embodiment, the flow rate adjusting valve (flow rate adjusting valve with check valve) 142 is used as means for restricting the flow of the vacuum breaking air flowing through the wafer chuck table 10, but in addition to this, a one-way throttle valve is used. May be used.
[0036]
Further, in the present embodiment, the example in which the wafer chuck table 10 according to the present invention is applied to the wafer chamfering apparatus 50 has been described. However, the wafer chuck table 10 according to the present invention can also be applied to other wafer manufacturing apparatuses. .
[0037]
【The invention's effect】
As described above, according to the present invention, it is possible to efficiently drain the liquid accumulated in the drain separator in a short time by effectively using the vacuum breaking air supplied at the time of the vacuum breaking. In addition, since the air of low pressure is supplied to the wafer chuck table, the wafer adsorption can be released without causing the wafer to break.
[Brief description of the drawings]
FIG. 1 is a front sectional view showing the structure of a wafer chamfering apparatus. FIG. 2 is a plan view showing the structure of a wafer chamfering apparatus. FIG. 3 is a plan view showing the structure of a wafer chuck table. Sectional view [FIG. 5] YY sectional view of FIG. 3 [FIG. 6] ZZ sectional view of FIG. [FIG. 7] Conceptual diagram showing the circuit configuration of the air piping connected to the wafer chuck table (at the time of wafer adsorption) )
FIG. 8 is a conceptual diagram showing the circuit configuration of the air piping connected to the wafer chuck table (at the time of vacuum break)
FIG. 9 is a front sectional view showing the configuration of the drain separator.
DESCRIPTION OF SYMBOLS 10 ... Wafer chuck table 50 ... Wafer chamfering device 120 ... Air piping 122 ... Vacuum pump 124 ... Drain separator 132 ... Draining pipe 134 ... Drain valve 136 ... Vacuum switching valve 138 ... Vacuum breaking air supply piping 142 ... Flow rate adjustment valve

Claims (1)

In the wafer chuck table that is connected to the vacuum generation means via the drain separator and holds the wafer placed on the upper surface by vacuum suction,
An air supply means connected in the middle of a pipe line connecting the drain separator and the vacuum generating means, and supplying vacuum breaking air to the wafer chuck table;
A flow rate adjusting valve provided in the middle of a pipe line connecting the drain separator and the wafer chuck table;
And restricting the flow rate of the vacuum breaking air supplied at the time of vacuum breaking of the wafer chuck table to a predetermined flow rate by the flow rate adjusting valve, so that the liquid accumulated in the drain separator with the air pressure of the vacuum breaking air is A wafer chuck table characterized by draining.

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