JP4446246B2 - Work suction device - Google Patents

Description

  The present invention relates to a workpiece suction device, and more particularly, to a workpiece suction device that holds a workpiece such as a semiconductor wafer polished by chemical mechanical polishing (CMP) by suction.

  With the development of semiconductor technology, miniaturization of design rules and multilayer wiring are progressing. For this reason, when it is going to form the pattern of the next layer as it is on the layer in which the pattern was formed like before, it is difficult to form a good pattern in the next layer because of the unevenness of the previous layer. Met. Therefore, the surface of the layer on which the pattern is formed is flattened, and then the pattern of the next layer is formed. As a planarization apparatus in this case, a wafer polishing apparatus using a CMP method is used.

  Conventionally, this type of polishing apparatus is composed of a polishing surface plate and a wafer holding head each rotated by an independent rotation mechanism, and is attached to the polishing surface plate with the semiconductor wafer held by the wafer holding head. By pressing against the polishing cloth and supplying a slurry as an abrasive, the surface of the semiconductor wafer is mechanically polished while being chemically corroded.

  In such a polishing apparatus, in order to simplify the wafer transfer mechanism, a wafer holding head is also used as a wafer transfer head. The wafer holding head also sucks water droplets (processing liquid, cleaning liquid, etc.) adhering to the wafer when adsorbing the wafer. A suction device having a drain tank for storing is known (for example, Patent Document 1). The drainage liquid accumulated in the drain tank is forcibly drained from the drain tank by opening the drain tank drain valve to open the drain tank to the atmosphere and then supplying pressurized air to the drain tank.

In addition, the suction holding unit that sucks and holds the workpiece is not limited to the wafer holding head applied to the polishing apparatus, and covers all suction holding units that vacuum-suck the workpiece to be processed.
JP-A-6-106474

  However, when the drainage liquid collected in the drain tank is drained, the work suction device of Patent Document 1 needs to open the drain tank to the atmosphere first because the drain tank is maintained in vacuum. For this reason, during the automatic polishing operation, that is, when the wafer holding head is holding the wafer by suction, the drainage liquid in the drain tank cannot be discharged, and the operation is stopped when draining. Therefore, there is a problem that the polishing efficiency of the wafer is lowered, and it is very difficult to measure the timing for stopping the operation of the apparatus. Furthermore, when the semiconductor wafer is again adsorbed and held by the wafer holding head after draining the drainage, the drain tank must be evacuated again, and the polishing process is interrupted during this time, which is also the polishing process efficiency. Was the cause of the decline. Furthermore, since the drainage drainage of the drain tank is not automated, the drainage timing of the drainage drainage was determined by visual inspection or the like by an operator.

  The present invention has been made in view of such circumstances, and it is possible to drain the waste liquid accumulated in the drain tank even during the suction conveyance of the workpiece, and the workpiece suction capable of automating the drainage drainage treatment. An object is to provide an apparatus.

In order to achieve the above-mentioned object, the invention according to claim 1 is connected to the decompression line and vacuum-suction mechanism for vacuum-sucking the workpiece to be processed, and is attached to the decompression line so that the vacuum is achieved. A first drain tank in which the drained liquid that is held and sucked in by the reduced pressure adsorption mechanism is collected via a reduced pressure line, a second drain tank that communicates with the first drain tank, and the first A first valve for discharging the drainage liquid accumulated in the drain tank to the second drain tank, a second valve for opening the second drain tank to the atmosphere, and the second drain tank. A third valve for draining the accumulated drainage liquid to the outside, and connected to the decompression line and held in vacuum, and a connection line is connected to the second drain tank. A buffer tank connected to, together provided in the connecting line, is characterized in that and a fourth valve for decompressing the second drain tank by a vacuum of the buffer tank by being opened .

  The invention according to claim 1 includes a first drain tank, a second drain tank, and a buffer tank, and controls opening and closing timings of first to second valves attached to these tanks. Accordingly, it is possible to automate the drainage drainage during the suction conveyance of the workpiece and the drainage drainage treatment.

  The invention according to claim 2 is characterized in that the buffer tank has a volume larger than that of the second drain tank.

The invention according to claim 3 is characterized in that the second drain tank is directly below the first drain tank .

  The invention according to claim 4 is provided with a water level detecting means for detecting the water level of the drained liquid collected in the first drain tank, and based on the water level information from the water level means, the first valve And a control unit for controlling the opening and closing operations of the second valve, the third valve, and the fourth valve, respectively.

  Specifically, as described in claim 6, when the drainage drainage information is output from the water level detection means attached to the first drain tank in the vacuum state during the suction conveyance of the workpiece, The first valve is opened, and the drainage liquid stored in the first drain tank is discharged to the second drain tank that is also in a vacuum state. Next, the control unit closes the first valve to shut off the first drain tank and the second drain tank. Next, the control unit opens the second valve to open only the second drain tank to the atmosphere, and opens the third valve to drain the waste liquid stored in the second drain tank to the outside. . Then, the control unit closes the third valve to seal the second drain tank, and opens the fourth valve to depressurize the second drain tank by the vacuum of the buffer tank. As a result, the first drain tank in which the drainage is actually accumulated is always in a vacuum state, so that the drainage drainage can be performed while the workpiece is being sucked and transported. By controlling the opening and closing of the valve 4, it becomes possible to automate the drainage and drainage treatment.

  According to a fifth aspect of the present invention, there is provided a control unit that controls the opening / closing operations of the first valve, the second valve, the third valve, and the fourth valve. .

  Specifically, as described in claim 7, when a predetermined time has elapsed, the control unit first opens the first valve and discharges the liquid stored in the first drain tank in the same vacuum state. To the second drain tank. Next, the control unit closes the first valve to shut off the first drain tank and the second drain tank. Next, the control unit opens the second valve to open only the second drain tank to the atmosphere, and opens the third valve to drain the waste liquid stored in the second drain tank to the outside. . Then, the control unit closes the third valve to seal the second drain tank, and opens the fourth valve to depressurize the second drain tank by the vacuum of the buffer tank. As a result, the first drain tank in which the drainage is actually accumulated is always in a vacuum state, so that the drainage drainage can be performed while the workpiece is being sucked and transported. By controlling the opening and closing of the valve 4, it becomes possible to automate the drainage and drainage treatment.

  According to an eighth aspect of the present invention, in order to achieve the above object, a vacuum suction mechanism that is connected via a vacuum line and vacuum-sucks a workpiece to be processed, and disposed in the vacuum line, the vacuum suction The first drain tank and the second drain tank, and the first drain tank and the second drain tank in which the drained liquid sucked by the mechanism is collected through the decompression line are connected to the decompression adsorption mechanism. A switching valve that alternately communicates with the first drain tank, a first valve that opens the first drain tank to the atmosphere, a second valve that opens the second drain tank to the atmosphere, and the first drain tank A third valve for draining drainage to the outside, a fourth valve for draining drainage accumulated in the second drain tank to the outside, and the decompression line. A buffer tank that is continued to be held in vacuum, and is provided in the decompression line between the buffer tank and the first drain tank, and is opened to open the first drain tank by the vacuum of the buffer tank. Is provided in the pressure reducing line between the buffer tank and the second drain tank, and is opened to decompress the second drain tank by the vacuum of the buffer tank. And a sixth valve.

  The invention according to claim 8 includes a first drain tank, a second drain tank, and a buffer tank, and the switching timings of the switching valve and the first to sixth valves attached to these tanks are controlled. By controlling it, it is possible to automate the drainage drainage and the drainage drainage treatment during the adsorption transfer of the workpiece.

  The invention according to claim 9 is characterized in that the buffer tank has a volume larger than the volumes of the first drain tank and the second drain tank.

  The invention according to claim 10 is the first water level detection means for detecting the water level of the drainage collected in the first drain tank, and the level of the drainage collected in the second drain tank. And a second water level detecting means for detecting water, and based on the water level information from the first water level means and the second water level means, the switching valve, the first valve, and the second valve. And a control unit for controlling the opening and closing operations of the third valve, the fourth valve, the fifth valve, and the sixth valve, respectively.

  Specifically, according to a twelfth aspect of the present invention, the control unit discharges the drainage water from the first water level detection means of the first drain tank in a vacuum state in which the drainage is accumulated during the suction conveyance of the workpiece. When the information is output, first, the switching valve is switched so that the second drain tank side communicates with the reduced pressure adsorption mechanism. As a result, the first drain tank is disconnected from the reduced pressure adsorption mechanism. Then, the control unit opens the first valve to release the first drain tank to the atmosphere, and then opens the third valve to drain the waste liquid accumulated in the first drain tank. Next, the control unit closes the first valve and the third valve, opens the fifth valve, and depressurizes the first drain tank by the vacuum of the buffer tank to quickly return to the vacuum state. . Next, when the drainage drainage information is output from the second water level detection means of the second drain tank in which the drainage is stored, the control unit first sets the first drain tank side to the reduced pressure adsorption mechanism by the switching valve. Switch to communicate. As a result, the second drain tank is disconnected from the reduced pressure adsorption mechanism. Then, the control unit opens the second valve to open the second drain tank to the atmosphere, and then opens the fourth valve to drain the waste liquid accumulated in the second drain tank. Next, the control unit closes the second valve and the fourth valve, opens the sixth valve, and depressurizes the second drain tank by the vacuum of the buffer tank, and quickly returns to the vacuum state. . Accordingly, one of the first drain tank and the second drain tank in which the drainage is actually accumulated is always in a vacuum state, so that drainage drainage can be performed while the workpiece is being sucked and transferred. Further, as described above, the drainage and drainage treatment can be automated by controlling the opening and closing of the switching valve and the first to sixth valves by the control unit.

  According to an eleventh aspect of the present invention, there is provided the switching valve, the first valve, the second valve, the third valve, the fourth valve, the fifth valve, and the sixth valve. It is characterized by having a control unit for controlling the opening / closing operation.

  Specifically, as described in claim 13, the control unit first switches the second drain tank side to communicate with the reduced pressure adsorption mechanism by the switching valve. As a result, the first drain tank is disconnected from the reduced pressure adsorption mechanism. Then, the control unit opens the first valve to release the first drain tank to the atmosphere, and then opens the third valve to drain the waste liquid accumulated in the first drain tank. Next, the control unit closes the first valve and the third valve, opens the fifth valve, and depressurizes the first drain tank by the vacuum of the buffer tank to quickly return to the vacuum state. . Next, when a predetermined time has elapsed, the control unit first switches the first drain tank side to communicate with the reduced pressure adsorption mechanism by the switching valve. As a result, the second drain tank is disconnected from the reduced pressure adsorption mechanism. Then, the control unit opens the second valve to open the second drain tank to the atmosphere, and then opens the fourth valve to drain the waste liquid accumulated in the second drain tank. Next, the control unit closes the second valve and the fourth valve, opens the sixth valve, and depressurizes the second drain tank by the vacuum of the buffer tank, and quickly returns to the vacuum state. . Accordingly, one of the first drain tank and the second drain tank in which the drainage is actually accumulated is always in a vacuum state, so that drainage drainage can be performed while the workpiece is being sucked and transferred. Further, as described above, the drainage and drainage treatment can be automated by controlling the opening and closing of the switching valve and the first to sixth valves by the control unit.

  According to the workpiece suction device according to the present invention, the first and second drain tanks and the buffer tank are provided, and the opening and closing timings of the first and second valves attached to these tanks are controlled. Therefore, the drainage drainage and the drainage drainage treatment during the adsorption transfer of the workpiece can be automated.

  Further, according to the workpiece suction device of the present invention, the first drain tank, the second drain tank, and the buffer tank are provided, and the switching valves and the first to sixth valves attached to these tanks. Since the opening / closing timing is controlled, the drainage drainage and drainage drainage treatment during the adsorption transfer of the workpiece can be automated.

  Hereinafter, preferred embodiments of a workpiece suction device according to the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a diagram illustrating a configuration of a workpiece suction device 10 according to an embodiment. A workpiece suction apparatus 10 shown in the figure is an apparatus applied to a polishing apparatus that polishes a semiconductor wafer W by a CMP method, and includes a decompression pump 12, a wafer holding head (a decompression suction mechanism) 14, a first drain. Tank 16, water level sensor (water level detection means) 18, second drain tank 20, first valve 22, three-way valve 28 comprising second valve 24 and fourth valve 26, third valve 30, buffer Mainly a tank (buffer tank) 32 and a CPU (control unit) 34 shown in FIG.

  The wafer holding head 14 is connected to the pressure reducing pump 12 via pressure reducing lines 36, 38 and 40, and the wafer W is sucked by the wafer holding head 14 under reduced pressure and transferred to a predetermined position.

  FIG. 3 is a cross-sectional view of an essential part showing an example of the wafer polishing apparatus 50. In this wafer polishing apparatus 50, a polishing cloth 54 is attached to the surface of a rotating polishing surface plate 52. Above the polishing cloth 54, the wafer holding head 14 is rotated while holding the wafer W, and is arranged so as to bring the wafer W into contact with the polishing cloth 54.

  The wafer holding head 14 includes a head main body 56, a back plate 58, a retainer ring 60, a protective sheet 62, a back plate airbag 64, a retainer ring airbag 66, and the like.

  The back plate airbag 64 is a space formed by the rubber sheet 68 and the head main body 56, supplied with air from the air line 70, and pressurizes the back plate 58 toward the polishing cloth 54. The retainer ring airbag 66 is a space formed by the rubber sheet 68 and the head main body 56 and is provided on the outer peripheral side of the back plate airbag 64. Air is supplied from the air line 72 to the retainer ring airbag 66 and presses the retainer ring 60 toward the polishing pad 12.

  Further, air jets 74, 74... Are formed on the outer surface of the lower surface of the back plate 58, and air jets 76, 76. The air outlets 74, 74... Are connected to the main air injection path 78, while the air outlets 76, 76... Are connected to the positive pressure line and the pressure reducing line 36 in FIG. It is connected. Therefore, the wafer W is adsorbed under reduced pressure by the wafer holding head 14 by opening the pressure reducing line 36 by the switching valve.

  The protective sheet 62 is held by the retainer ring 60 at the periphery, and prevents the wafer W from coming into direct contact with the hard back plate 58 and abuts against the wafer W to apply air pressure from the back plate 58 to the wafer W. introduce. The air injected from the back plate 58 is exhausted to the outside through the gap between the back plate 58 and the retainer ring 60. The polishing shape of the wafer W is controlled by adjusting the air pressure through the main air path 78 and the air pressure through the sub air path 80, respectively.

  The protective sheet 62 has a suction port (not shown) for wafer suction, and is used to suck and hold the wafer W when the wafer W is transported. That is, when the wafer W is attracted, the sub air path 80 is switched to the decompression line 36 by the switching valve, and the suction force is transmitted to the wafer W via the plurality of suction ports.

  The wafer holding head 14 is configured as described above, and the wafer W held by the wafer holding head 14 is pressed against the polishing cloth 54 on the polishing surface plate 52, and the polishing surface plate 52 and the wafer holding head 14 rotate. However, the wafer W is polished by supplying slurry onto the polishing pad 54.

  On the other hand, the first drain tank 16 shown in FIG. 1 is installed between the decompression line 36 and the decompression line 38, and the inside thereof is always kept in a vacuum. Therefore, the drained liquid sucked by the wafer holding head 14 is stored in the first drain tank 16 through the pressure reducing line 36.

  A water level sensor 18 is attached to the first drain tank 16. The water level sensor 18 is a sensor that detects the level of drainage accumulated in the first drain tank 16, and is at a height position that detects that the drainage is sufficiently accumulated in the first drain tank 16. It is attached. A signal indicating that the liquid level of the drainage is detected by the water level sensor 18 is output to the CPU 34 shown in FIG. 2, and the CPU 34 opens and closes the first to fourth valves 22, 24, 26, and 30 based on this signal. To control.

  The first valve 22 is a valve for discharging the drainage liquid accumulated in the first drain tank 16 to the second drain tank 20, and the second valve 24 opens the second drain tank 20 to the atmosphere. It is a valve to make it. In addition, the third valve 30 is a valve for draining the drainage liquid accumulated in the second drain tank 20 to the outside, and the fourth valve 26 is opened by the vacuum of the buffer tank 32 by being opened. 2 is a valve for depressurizing the second drain tank 20.

  Here, the first drain tank 16 and the second drain tank 20 are defined as one drain tank A, and the space between the first drain tank 16 and the second drain tank 20 is divided by a shielding plate such as a gate valve, and then drained in a similar sequence. The case is essentially the same as the contents of the present invention.

  The buffer tank 32 is connected to the decompression pump 12 and maintained in a vacuum, and is connected to the second drain tank 20 via a connection line 82. A three-way valve 28 composed of the second valve 24 and the fourth valve 26 is attached to the connecting line 82. The buffer tank 32 has a capacity that is overwhelmingly larger than the volume of the second drain tank 20 in order to instantaneously return the second drain tank 20 to a vacuum state. For example, a capacity of 30 l is used for a capacity of 500 ml of the second drain tank.

  Next, the control method of the workpiece | work adsorption | suction apparatus 10 by CPU34 shown in FIG. 3 is demonstrated.

  The CPU 34 discharges drainage information from the water level sensor 18 attached to the first drain tank 16 in a vacuum state when the wafer W is attracted by the wafer holding head 14 (the drainage is sufficiently accumulated in the first drain tank 16. Is output, or when a predetermined time has elapsed, first, the first valve 22 is opened, and the drainage liquid stored in the first drain tank 16 is discharged into the second vacuum state. Discharge into the drain tank 20. Next, the CPU 34 closes the first valve 22 and shuts off the first drain tank 16 and the second drain tank 20. Next, the CPU 34 opens the second valve 24 to open only the second drain tank 20 to the atmosphere, and opens the third valve 30 to discharge the waste liquid stored in the second drain tank 20 to the outside. Drain into. Then, the CPU 34 closes the third valve 30 to seal the second drain tank 20 and opens the fourth valve 26 to depressurize the second drain tank 20 by the vacuum of the buffer tank 32. . As a result, the first drain tank 16 in which the drainage is actually accumulated is always in a vacuum state, so that the drainage drainage can be performed when the wafer W is adsorbed by the wafer holding head 14. By controlling the opening and closing of the first to fourth valves 22, 24, 26, 30, it becomes possible to automate the drainage and drainage treatment without manual intervention.

  FIG. 4 is a timing chart showing an example of opening and closing operations of the first to fourth valves 22, 24, 26, and 30 by the CPU 34 shown in FIG.

  According to FIG. 4, first, at time t1 when the power is turned on, the first valve 22 and the third valve 30 are closed, and the second valve 24 of the three-way valve 28 is opened and the fourth valve is opened. The valve 26 is closed and set to the atmosphere opening side. Next, only the third valve 30 is opened at time t2 at the start of the initial state, and this state continues until time t3 at the end of the initial. Next, at time t3 at the end of the initial, the third valve 30 is closed, and at the same time, the second valve 24 of the three-way valve 28 is closed and the fourth valve 26 is opened to change the setting to the vacuum side. Is done. As a result, the second drain tank 20 shown in FIG. 1 is depressurized by the vacuum of the buffer tank 32 and instantaneously enters a vacuum state.

  Thereafter, at time t4 as shown in FIG. 4, the first valve 22 is opened, and this state is continued until time t5. At time t5, the first valve 22 is closed. Here, the required time a from time t3 to t4 is the “switching time”, and is the time for the vacuum degree of the second drain tank 20 opened to the atmosphere for drainage drainage to rise to a specified value. The drained liquid sucked by the wafer holding head 14 during the required time “a” is stored in the first drain tank 16. Further, the required time b from the time t4 to the time t5 is an “operation time”, and is a time for collecting the drained liquid sucked by the vacuum from the first drain tank 16 to the second drain tank 20.

  Thereafter, at time t6, the third valve 30 is opened, the second valve 24 of the three-way valve 28 is opened, and the fourth valve 26 is closed to be set to the atmosphere release side. This state continues until time t7. As a result, the second drain tank 20 is opened to the atmosphere, and the third valve 30 is also opened, so that the drainage stored in the second drain tank 20 is drained from the second drain tank 20 to the outside. . At this time, since the first valve 22 is closed, the first drain tank 16 is maintained in a vacuum state, and the drained liquid sucked by the wafer holding head 14 is continuously stored. Here, the required time c from time t5 to t6 is “pre-drainage time”, and as a preparation before drainage drainage, the first valve 22 is closed in advance before opening to the atmosphere. It takes time. Further, the required time d from time t6 to time t7 is “drainage time”, which is the time for draining the drainage liquid accumulated in the second drain tank 20. As described above, the CPU 34 sets the opening / closing timings of the first to fourth valves 22, 24, 26, 30 with each required time of a, b, c, d as one cycle within the time from time t3 to time t7. By controlling, the drainage drainage treatment during wafer transfer by the wafer holding head 14 can be performed, and the drainage drainage treatment can be automated.

  The line L connecting the valve 26 and the valve 26 to the buffer tank 32 is necessary when the volume of the second drain tank 20 is sufficiently small and does not affect the vacuum pressure of the first drain tank 16. May not.

  FIG. 5 is a diagram illustrating a configuration of a workpiece suction device 100 according to another embodiment. A workpiece suction apparatus 100 shown in FIG. 1 includes a decompression pump 102, a wafer holding head (decompression suction mechanism) 104, a first drain tank 106, a first water level sensor 108, a second drain tank 110, and a second water level sensor. 112, a switching valve 114, a three-way valve 120 comprising a first valve 116 and a fifth valve 118, a third valve 122, a three-way valve 128 comprising a second valve 124 and a sixth valve 126, a fourth valve The valve 130, the buffer tank (buffer tank) 132, and the CPU (control unit) 134 shown in FIG. 6 are mainly configured.

  The wafer holding head 104 is connected to the pressure reducing pump 102 via pressure reducing lines 136, 138, 140, 142, and the wafer W is sucked by the wafer holding head 104 under reduced pressure and is transported to a predetermined position. Since the wafer holding head 104 and the wafer holding head 14 shown in FIG. 3 have the same structure, detailed description of the wafer holding head 104 is omitted here.

The first drain tank 106 shown in FIG. 5 is installed between the decompression line 136 and the decompression line 138, and the inside is always maintained in a vacuum. Therefore, the first drain tank 106, waste liquid sucked by the wafer holding head 104 is accumulated through the vacuum line 1 36.

  Further, the switching valve 114 is provided in the pressure reducing line 136, and the path of the pressure reducing line 136 is switched to the first drain tank 106 side or the second drain tank 110 side by the switching operation of the switching valve 114. It is done.

  A water level sensor 108 is attached to the first drain tank 106. The water level sensor 108 is a sensor that detects the level of the drainage liquid stored in the first drain tank 106, and is at a height position that detects that the drainage liquid has sufficiently accumulated in the first drain tank 106. It is attached. Similarly, a water level sensor 112 is also attached to the second drain tank 110. The water level sensor 112 is a sensor that detects the level of the drainage accumulated in the second drain tank 110, and is at a height position that detects that the drainage is sufficiently accumulated in the second drain tank 110. It is attached. A signal indicating that the liquid level of the drainage is detected by the water level sensors 108 and 112 is output to the CPU 134 shown in FIG. 6, and the CPU 134 switches the switching valve 114 and the first to sixth valves 116 and 118 based on this signal. , 122, 124, 126, and 130 are controlled.

  The first valve 116 is a valve for opening the first drain tank 106 to the atmosphere, and the second valve 124 is a valve for opening the second drain tank 110 to the atmosphere. Further, the third valve 122 is a valve for draining the drainage liquid accumulated in the first drain tank 106 to the outside, and the fourth valve 130 is the drainage liquid accumulated in the second drain tank 110. A valve for draining to the outside. Furthermore, the fifth valve 118 is a valve that depressurizes the first drain tank 106 by the vacuum of the buffer tank 132 when opened, and the sixth valve 126 opens the buffer tank 132 when opened. This is a valve that depressurizes the second drain tank 110 by vacuum.

  The buffer tank 132 is connected to the decompression pump 102 and held in vacuum, is connected to the first drain tank 106 via the decompression line 138, and is connected to the second drain tank 110 via the decompression line 140. It is connected. A three-way valve 120 composed of a first valve 116 and a fifth valve 118 is attached to the decompression line 138, and a three-way valve 128 composed of a second valve 124 and a sixth valve 126 is attached to the decompression line 140. ing. Note that the buffer tank 132 is overwhelmingly larger than the volumes of the first drain tank 106 and the second drain tank 110 in order to instantaneously return the first and second drain tanks 106 and 110 to a vacuum state. A capacity is used. For example, a capacity of 30 l is used for a capacity of 500 ml of the second drain tank.

  Next, the control method of the workpiece | work adsorption | suction apparatus 100 by CPU134 shown in FIG. 6 is demonstrated.

  When the drainage / drainage information is output from the first water level sensor 108 of the first drain tank 106 in the vacuum state where the drainage is stored, the CPU 134 sucks the wafer W by the wafer holding head 104. Alternatively, when the CPU 134 performs time management with a timer, when the predetermined time has elapsed, first, the switching valve 114 switches the second drain tank 110 side to communicate with the wafer holding head 104. As a result, the first drain tank 106 is disconnected from the wafer holding head 104.

  Then, the CPU 134 opens the first valve 116 to release the first drain tank 106 to the atmosphere, and then opens the third valve 122 to drain the waste liquid accumulated in the first drain tank 106 to the outside. To do.

  Next, the CPU 134 closes the first valve 116 and the third valve 122, opens the fifth valve 118, and depressurizes the first drain tank 106 by the vacuum of the buffer tank 132, thereby reducing the vacuum state. To return quickly.

  Next, when the drainage / drainage information is output from the second water level sensor 112 of the second drain tank 110 in which the drainage is stored, or when the CPU 134 performs time management by the timer, the CPU 134 performs a predetermined process. When time elapses, first, the switching valve 114 is switched so that the first drain tank 106 side communicates with the wafer holding head 104. As a result, the second drain tank 110 is disconnected from the wafer holding head 104.

  Then, the CPU 134 opens the second valve 124 to release the second drain tank 110 to the atmosphere, and then opens the fourth valve 130 to drain the waste liquid accumulated in the second drain tank 110 to the outside. To do.

  Next, the CPU 134 closes the second valve 124 and the fourth valve 130, opens the sixth valve 126, and depressurizes the second drain tank 110 by the vacuum of the buffer tank 132. To return quickly.

  Accordingly, at least one of the first drain tank 106 and the second drain tank 110 in which the drainage is actually accumulated is always in a vacuum state, so that drainage drainage can be performed during wafer transfer. In addition, as described above, the CPU 34 can control the opening and closing of the switching valve 114 and the first to sixth valves 116, 118, 122, 124, 126, and 130 to automate the drainage and drainage treatment. Become.

  1 and 5, the pressure reducing pumps 12 and 102 are used. However, when a pressure reducing pump with a high exhaust speed is used, the buffer tank may not be provided. Therefore, when there is no buffer tank, the fifth valve and the sixth valve do not exist, and the CPU 134 controls opening / closing of valves other than the fifth valve and the sixth valve.

Explanatory drawing which showed the structure of the workpiece | work adsorption | suction apparatus of embodiment typically The block diagram which shows the control system of the workpiece | work adsorption | suction apparatus shown in FIG. Vertical sectional view of the wafer holding head of the embodiment Timing chart showing valve opening / closing time of the workpiece suction device shown in FIG. Explanatory drawing which showed the structure of the workpiece | work adsorption | suction apparatus of other embodiment typically The block diagram which shows the control system of the workpiece | work adsorption | suction apparatus shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10,100 ... Work adsorption | suction apparatus, 12, 102 ... Decompression pump, 14, 104 ... Wafer holding head, 16, 106 ... First drain tank, 18, 108 ... Water level sensor, 20, 110 ... Second drain tank, 22, 116 ... first valve, 24, 124 ... second valve, 26, 130 ... fourth valve, 30, 122 ... third valve, 32 ... buffer tank, 34, 134 ... CPU, 118 ... first 5 valves, 126 ... sixth valve

Claims (13)

A vacuum suction mechanism that is connected via a vacuum line and vacuum-sucks a workpiece to be processed;
A first drain tank that is held in a vacuum by being attached to the decompression line and that collects the drained liquid sucked by the decompression adsorption mechanism via the decompression line;
A second drain tank communicated with the first drain tank;
A first valve for discharging the drainage liquid accumulated in the first drain tank to the second drain tank;
A second valve for opening the second drain tank to the atmosphere;
A third valve for draining the waste liquid accumulated in the second drain tank to the outside;
A buffer tank connected to the decompression line and held in vacuum, and connected to the second drain tank via a connection line;
A fourth valve that is provided in the connection line and is opened to depressurize the second drain tank by the vacuum of the buffer tank;
A workpiece suction device characterized by comprising:   The workpiece suction device according to claim 1, wherein the buffer tank has a volume larger than a volume of the second drain tank. The work suction device according to claim 1, wherein the second drain tank is directly below the first drain tank .   Water level detection means for detecting the water level of the drained liquid collected in the first drain tank is provided, and based on the water level information from the water level means, the first valve, the second valve, 4. The work suction device according to claim 3, further comprising: a control unit that controls opening and closing operations of the third valve and the fourth valve. 5.   The workpiece suction device according to claim 3, further comprising a control unit that controls opening and closing operations of the first valve, the second valve, the third valve, and the fourth valve. .   When the water level upper limit information is output from the water level detecting means, the control unit first opens the first valve and discharges the liquid stored in the first drain tank to the second drain tank. Then, the first valve is closed to shut off the first drain tank and the second drain tank, and then the second valve is opened to open the second drain tank to the atmosphere. At the same time, the third valve is opened to drain the drainage liquid stored in the second drain tank to the outside, and the third valve is closed to open the fourth valve. 5. The opening / closing operation of each of the first valve, the second valve, the third valve, and the fourth valve is controlled so that the drain tank is depressurized by the vacuum of the buffer tank. of Over click adsorber.   When a predetermined time elapses, the control unit first opens the first valve to discharge the drainage liquid stored in the first drain tank to the second drain tank, and then The first valve is closed to shut off the first drain tank and the second drain tank, and then the second valve is opened to open the second drain tank to the atmosphere and the third valve is opened. The drained liquid accumulated in the second drain tank is drained to the outside, and the third valve is closed and the fourth valve is opened, so that the second drain tank is connected to the buffer tank. 6. The workpiece suction device according to claim 5, wherein opening / closing operations of the first valve, the second valve, the third valve, and the fourth valve are controlled so as to reduce the pressure by vacuum. A vacuum suction mechanism that is connected via a vacuum line and vacuum-sucks a workpiece to be processed;
A first drain tank and a second drain tank, which are disposed in the decompression line and in which drained liquid sucked by the decompression adsorption mechanism is collected via the decompression line;
A switching valve for alternately communicating the first drain tank and the second drain tank to the reduced pressure adsorption mechanism;
A first valve for opening the first drain tank to the atmosphere;
A second valve for opening the second drain tank to the atmosphere;
A third valve for draining the waste liquid accumulated in the first drain tank to the outside;
A fourth valve for draining the drainage liquid accumulated in the second drain tank to the outside;
A buffer tank connected to the vacuum line and held in vacuum;
A fifth valve provided in the decompression line between the buffer tank and the first drain tank and opened to decompress the first drain tank by a vacuum of the buffer tank;
A sixth valve provided in the decompression line between the buffer tank and the second drain tank and opened to decompress the second drain tank by a vacuum of the buffer tank;
A workpiece suction device characterized by comprising:   9. The workpiece suction device according to claim 8, wherein the buffer tank has a volume larger than volumes of the first drain tank and the second drain tank.   First water level detecting means for detecting the water level of the drained liquid collected in the first drain tank, and second water level detecting means for detecting the water level of the drained liquid collected in the second drain tank And based on the water level information from the first water level means and the second water level means, the switching valve, the first valve, the second valve, the third valve, The workpiece suction device according to claim 8, further comprising a control unit that controls opening and closing operations of the four valves, the fifth valve, and the sixth valve.   A control unit for controlling opening / closing operations of the switching valve, the first valve, the second valve, the third valve, the fourth valve, the fifth valve, and the sixth valve; The work suction device according to claim 8, further comprising: When the drainage drainage information is output from the first water level detection means of the first drain tank in which drainage is stored, the control unit first controls the second drain tank side by the switching valve. In addition to switching to communicate with the reduced pressure adsorption mechanism, the first valve is opened to release the first drain tank to the atmosphere, and then the third valve is opened to collect the waste accumulated in the first drain tank. Draining the liquid, then closing the first valve and the third valve and opening the fifth valve to depressurize the first drain tank by the vacuum of the buffer tank;
Next, when drainage drainage information is output from the second water level detection means of the second drain tank in which drainage is stored, first, the first drain tank side is decompressed and adsorbed by the switching valve. In addition to switching to communicate with the mechanism, the second valve is opened to open the second drain tank to the atmosphere, and then the fourth valve is opened to drain the waste liquid accumulated in the second drain tank. Then, the second valve and the fourth valve are closed, the sixth valve is opened, and the second drain tank is depressurized by the vacuum of the buffer tank. The work suction device according to claim 10, wherein the opening / closing operation of each of the second valve, the third valve, the fourth valve, the fifth valve, and the sixth valve is controlled. When a predetermined time elapses, the control unit first switches the second drain tank side to communicate with the reduced pressure adsorption mechanism by the switching valve, and opens the first valve to open the first drain. After the tank is opened to the atmosphere, the third valve is opened to drain the drainage liquid accumulated in the first drain tank. Next, the first valve and the third valve are closed and the fifth valve is closed. And the first drain tank is depressurized by the vacuum of the buffer tank.
Next, when a predetermined time elapses, first, the switching valve is switched so that the first drain tank side communicates with the reduced pressure adsorption mechanism, and the second valve is opened to bring the second drain tank into the atmosphere. After the opening, the fourth valve is opened to drain the drainage liquid accumulated in the second drain tank, and then the second valve and the fourth valve are closed and the sixth valve is opened. The first valve, the second valve, the third valve, the fourth valve, the fifth valve, and the sixth valve are opened so that the second drain tank is depressurized by the vacuum of the buffer tank. The workpiece suction device according to claim 11, wherein each of the opening and closing operations is controlled.

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