JPH0727154U - Air pressure release circuit of wafer vacuum suction holding mechanism - Google Patents

Abstract

(57) [Abstract] [Purpose] A wafer vacuum suction holding mechanism that holds a wafer by suction to convey it, has an inexpensive structure, and prevents dust from being discharged from the suction port when the suction is released.
(EN) Provided is an air pressure releasing circuit which prevents a decrease in yield in a VLSI manufacturing process. [Structure] The air passage 3 connected to the three suction ports 4a, 4b and 4c of the fork 2 is structured so as to pass through each suction port, and the end of the air route 3a is provided with a solenoid valve 6.
Is connected to the vacuum pump 8 via. Air path 3d
Is connected to a solenoid valve 7 via an air-filter 5. When adsorbing the wafer 1, the solenoid valve 7 is closed,
Open the solenoid valve 6. To release the wafer 1 by suction, the solenoid valve 7 is first opened, and the solenoid valve 6 is closed with a certain time lag.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a wafer vacuum suction holding mechanism that holds a wafer for transportation in order to process the wafer in a VLSI manufacturing process, and more specifically, a wafer for suppressing dust generation during the transportation process. (C) An air pressure release circuit of a vacuum suction holding mechanism.

[0002]

[Prior art]

 In the VLSI manufacturing process, automation and unmanned operation are progressing further, and dust generation from manufacturing equipment is a problem. Above all, in the process of transporting the wafer for the next process, when the wafer is released from adsorption, dust is discharged from the adsorption port and transferred to the adjacent wafer in the next step. Is deteriorating the yield.

FIG. 5 is a diagram showing an example of a conventional wafer vacuum suction holding mechanism. In order to adsorb the wafer 1, adsorption holes 14a, 14b and 14c are provided at three locations on the fork 12. An air passage 13 as shown in FIG. 5 is formed inside the fork 12, and the suction ports 14a, 14b and 14c are connected thereto. The end of the air path 13 is connected to the solenoid valve 15, and the solenoid valve 15 is connected to a vacuum pump 16.

When the wafer 1 is vacuum-adsorbed in order to be transferred to a predetermined storage container, the solenoid valve 15 is turned on to connect the vacuum pump 16 to the air passage 13, thereby adsorbing the vacuum at three places. Wafer 1 is adsorbed and held by the mouth. When the wafer 1 is transferred to a predetermined container and the wafer 1 is placed, the solenoid valve 15 is turned off and the vacuum pump side is switched to the air intake side.

[0005]

[Problems to be solved by the device]

 Therefore, there is a problem that the air flow instantly flows backward, and the dust generated by itself and the polluted air via the solenoid valve 15 are discharged from the adsorption ports 14a, 14b, and 14c. In order to solve this, as shown in FIG. 6, a measure is taken to insert an air filter 17 between the end of the air passage 13 and the solenoid valve 15. As a result, the dust of the air flow from the solenoid valve 15 side could be removed by the air filter 17, but the dust sucked from the suction ports 14a, 14b and 14c adhered to the suction side of the air filter 17. However, a new problem arose that the attached dust was discharged.

Further, in order to cope with this problem, an air operated valve 18 is inserted between the air filter 17 and the vacuum pump 16 as shown in FIG. However, the air-operated valve 18 is expensive, which has pushed up the price of the wafer vacuum suction holding mechanism. The purpose of the present invention is to reduce the pneumatic pressure of the wafer vacuum suction holding mechanism, which is an inexpensive structure and prevents the discharge of dust from the suction port at the time of suction release, and prevents the yield reduction in the VLSI manufacturing process. To provide a circuit.

[0007]

[Means for Solving the Problems]

 In order to achieve the above object, the pneumatic pressure release circuit of the wafer vacuum suction holding mechanism according to the present invention lowers the pneumatic pressure in the pipe via a solenoid valve when the wafer is transferred, and is connected to the pipe. The suction port provided at the tip of the air path inside the fork holds the one surface of the wafer by suction, and when the transfer of the wafer is finished, the air is introduced from the solenoid valve to hold it by suction. In the wafer vacuum suction holding mechanism for releasing the above, the air path in the fork is formed so as to pass through the suction port, and one end of the air path is connected to the vacuum pump via the first solenoid valve. When the second electromagnetic valve is connected and the other end of the air path is connected to the second solenoid valve via an air filter to adsorb and hold the wafer, the first solenoid valve is closed with the second solenoid valve closed. Open the solenoid valve and pull with the vacuum pump to suck the wafer. To release the hold, open the second solenoid valve to introduce air, and then close the first solenoid valve to keep the flow of air in the air path at the time of wafer adsorption and adsorption release. It is configured to be unidirectional.

[0008]

[Action]

 According to the above configuration, there is no instantaneous backflow when the vacuum state is released, and only one direction of airflow is always generated, and dust is only sucked from the suction port. The problem that is discharged from the suction port is solved. Therefore, the transfer of dust to the surface of the adjacent wafer is suppressed.

[0009]

【Example】

 Hereinafter, the present invention will be described in more detail with reference to the drawings. 1, 2 and 3 are views showing an embodiment of a pneumatic release circuit of a wafer vacuum suction holding mechanism according to the present invention. The air path 3 connected to the three suction ports 4a, 4b, and 4c of the fork 2 is structured so as to pass through each suction port, and the air route 3a passes through the suction port 4a. 3b, the air path 3b is connected to the air path 3c via the adsorption port 4b, and the air path 3c is connected to the air path 3d via the adsorption port 4c. The end of the air passage 3 a is connected to the solenoid valve 6, and the vacuum pump 8 is connected to the solenoid valve 6.

On the other hand, the end portion of the air passage 3d is connected to the solenoid valve 7 via the air-filter 5. 1 shows the suction state, FIG. 2 shows the state immediately after the suction release, and FIG. 3 shows the state after the suction release. FIG. 4 is a diagram for explaining the operation timing of the solenoid valves 6 and 7. When both the solenoid valves 6 and 7 are closed, the solenoid valves 6 and 7 are not adsorbed. In this state, when the suction ports 4a, 4b and 4c are brought close to the back surface of the wafer 1 and the electromagnetic valve 6 is opened with the vacuum pump 8 pulled (FIG. 1), the wafer 1 is sucked. At this time, the solenoid valve 7 is closed and connected to the blind plug 9, and the air flow does not flow in. The air remaining in the solenoid valve 7, in the middle of the pipe and in the air path 3 of the fork 2 is pulled by the vacuum pump 8, but the dust contained in the air remaining in the solenoid valve 7 is air. Blocked by filter 5.

Next, when the solenoid valve 7 is opened (FIG. 2), air flows in from the solenoid valve 7 and the adsorption of the wafer 1 is released. At this time, dust contained in the inflowing air is also blocked by the air-filter 5. Further, when the solenoid valve 6 is closed (FIG. 3), the connection with the vacuum pump 8 is cut off. With the vacuum pump 8 disconnected, the solenoid valve 7 is closed. When adsorption and desorption are performed by the above procedure, air is always drawn toward the vacuum pump, so the dust adhering to the back surface of the wafer 1 is sucked from the suction port and the sucked dust is removed. It is not discharged again from the suction port.

[0012]

[Effect of device]

 As described above, the present invention has a structure in which the air path in the fork is passed through each suction port, and one end of the air path is connected to the vacuum pump via the first solenoid valve. The other end is connected to the second solenoid valve via an air filter, and when the adsorption is released, the second solenoid valve is switched and then the first solenoid valve is switched. Therefore, it is cheaper than the conventional mechanism using an air-operated valve, and during adsorption and desorption, the air flow is always unidirectional and only sucks dust from the adsorption port and does not expel it. In this step, the dust is not transferred to the adjacent wafer and the yield can be prevented from decreasing.

[Brief description of drawings]

FIG. 1 is a diagram showing a suction state in an embodiment of an air pressure release circuit of a wafer vacuum suction holding mechanism according to the present invention.

FIG. 2 is a diagram showing an embodiment of an air pressure releasing circuit of the wafer vacuum suction holding mechanism according to the present invention, showing a state immediately after releasing the suction.

FIG. 3 is a view showing an embodiment of an air pressure releasing circuit of the wafer vacuum suction holding mechanism according to the present invention after the suction is released.

FIG. 4 is a diagram for explaining operation timings of two solenoid valves.

FIG. 5 is a view showing an example of a conventional wafer vacuum suction holding mechanism.

FIG. 6 is a view showing another example of a conventional wafer vacuum suction holding mechanism.

FIG. 7 is a view showing still another example of the conventional wafer vacuum suction holding mechanism.

[Explanation of symbols]

 1 ... Wafer 2, 12 ... Fork 3 ... In-fork air path 4a, 4b, 4c, 14a, 14b, 14c ... Adsorption port 5, 17 ... Air-filter 6, 7 ... Solenoid valve 8, 16 ... Vacuum pump 9 ... Blade stopper 15 ... Solenoid valve 18 ... Air operated valve

Claims (1)

[Scope of utility model registration request] 1. When conveying a wafer, the air pressure in the pipe is lowered via an electromagnetic valve, and the wafer is moved by a suction port provided at the tip of an air path in the fork connected to the pipe. In a wafer vacuum suction holding mechanism that sucks and holds one surface of the wafer, and releases suction holding by introducing air from the solenoid valve when the conveyance of the wafer is completed, the air in the fork A path is formed so as to pass through the adsorption port, one end of the air path is connected to a vacuum pump via a first electromagnetic valve, and the other end of the air path is connected to a second electromagnetic field via an air-filter. When the wafer is attached and held by suction, the first solenoid valve is opened with the second solenoid valve closed and pulled by the vacuum pump to release the wafer suction hold. Then open the second solenoid valve to introduce air, then The air pressure of the wafer vacuum suction holding mechanism is characterized in that the flow of the air path is always in one direction when the wafer is sucked and released by closing the first solenoid valve. Release circuit.