JPH1111664A - Work holding mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the holding of a substrate via only the detection of pressure by fixing a valve at the prescribed position of a drive rod, and changing the opening quantity of the atmospheric pressure chamber side inlet of a leak hole according to the relative movement between the drive rod and a piston via a spring. SOLUTION: When the force of a holding component 7 for gripping a substrate 1 is applied, a stopper 19 applied with the force from a drive rod 22 shrinks a small spring 21, and a leak hole inlet 16 between a piston 13 and a valve 20 starts to be opened. When the leak hole inlet 16 is opened, the gas flowing in the leak hole 17 is increased, and the value of a pressure sensor 5 becomes further approximate to the atmospheric pressure from the state when the piston 13 is located at the left end. When the piston 13 proceeds to the right side, a substrate hold section 7 is stopped with the substrate 1 kept pressed. When the substrate 1 cannot be held, the leak hole inlet 16 is not changed even if the piston 13 is operated. The value of the pressure sensor 5 shows different values according to the holding state, and the substrate 1 can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanism for holding a work such as a thin plate-shaped substrate, such as a semiconductor crystal substrate or a glass substrate, which needs to prevent foreign matter from adhering.

[0002]

2. Description of the Related Art Conventionally, when a semiconductor crystal substrate or the like is directly gripped and transported, as shown in FIG. 3, the back or front surface of the substrate 1 is vacuum-adsorbed by an adsorption plate 2 to hold the substrate 1. The check of the holding state operated by opening and closing the vacuum source 6 with the control valve 3 detects a pressure change of the pressure sensor 5 due to the blocking of the suction port 4 of the substrate 1. The advantages of this method are that the mechanism for holding is simple and the detection of holding is easy, and the disadvantage is that foreign matter easily adheres to the substrate 1 because it comes into contact with the surface of the substrate 1.

In another method, as shown in FIG. 4, an end surface of the substrate 1 is gripped and held by holding components 7 and 8 so as not to touch both surfaces of the substrate 1. This method has an advantage that foreign matter does not easily adhere to the plate surface of the substrate 1 because it contacts only the end face of the substrate 1, but two disadvantages are required as disadvantages.

The first point is that a new driving source 9 is required for the holding operation, and it is necessary to prevent the generation of foreign matter in the driving operation. Therefore, it is necessary to provide a foreign matter shielding structure or a foreign matter suction structure.

The second point is that a new sensor 10 and the like for detecting the holding state of the substrate 1 are required, and a power source or a pipe for the driving source 9 and a wiring 11 for the sensor 10 are connected.
Need to be added.

Normally, the substrate holding mechanism must be mounted on a portion that constantly moves, such as a robot hand, and wiring, piping, etc. for handling the above first and second points. Due to the installation of
It is difficult to increase reliability.

[0007]

SUMMARY OF THE INVENTION The present invention overcomes the drawbacks of the above-described end face holding method for holding a substrate, has a high reliability and has a simple structure, has no foreign matter generated by driving a mechanism, and holds the substrate. An object of the present invention is to provide a substrate holding mechanism having a vacuum drive cylinder that can perform detection only by pressure detection.

[0008]

In order to prevent the generation of foreign matter due to the holding operation of the substrate, a vacuum cylinder is used as a drive source, and a leak path for the vacuum source to constantly suck a small amount of fluid from the mechanism during this operation. Was provided.

In order to detect the load state due to the holding operation of the cylinder as a pressure fluctuation near the control valve for controlling the operation of the cylinder, a leak hole in which a leak path is further opened by the force of the cylinder load is provided. Was placed. In this pressure fluctuation detection, the holding state can be determined by detecting the lapse of time after the start of the operation of the control valve and the lapse of pressure.

The driving of the cylinder, the exhaust of foreign substances, and the detection of the operating state of the cylinder are performed by a single vacuum path in order to minimize the number of piping and wiring.

When the cylinder is returned (the control valve in the vacuum path is closed), the cylinder and the control valve are controlled so that the fluid continues to be sucked so that the change in the volume of the cylinder does not blow out to the mechanism side and emit foreign matter. A pipe having a sufficient volume for maintaining a vacuum was installed in the pipe between them.

When the vacuum cylinder of the drive source is driven in vacuum to hold the end face of the substrate, the piston starts to move.
At this time, since a small amount of air flows from the atmosphere side to the vacuum side through the leak path, the pressure on the vacuum side becomes slightly weak (approaching the atmospheric pressure).

At this time, foreign matter generated by the operation of the mechanism flows into the leak path together with the air and is sucked into the vacuum side, so that it does not blow out to the mechanism side.

When the piston moves further and the force generated by holding the substrate is applied, the small spring 21 contracts, the leak path is further opened, and the pressure on the vacuum side weakens. This makes it possible to detect the load state due to the cylinder holding operation by the change in pressure.

The leak amount is adjusted by giving a pressure loss before and after the throttle 23 so that the optimal setting of the driving force, the pressure detection, and the suction of the foreign matter can be adjusted.

By using a single vacuum path for driving the cylinder, exhausting foreign matter, and detecting the operating state of the cylinder, a single connection to the moving part is possible, and reliability against disconnection and the like is improved. Can be enhanced.

At the time of the return operation of the piston (the control valve of the vacuum path is closed), since there is a sufficient volume between the cylinder and the control valve, it is necessary to maintain the suction amount of the leak path larger than the volume of the air pushed back by the piston. Accordingly, it is possible to prevent the generation of foreign matter due to the return operation of the mechanism.

[0018]

FIG. 1 shows a first embodiment of the present invention.

The piston 13 is inside the cylinder 14, and a spring 15 acts on the piston 13 in a direction in which the spring extends. When the control valve 3 in the vacuum path is closed, the spring 15
Is equilibrated to the atmospheric pressure, the piston is in contact with the left end in the figure, and the leak hole inlet 16 is closed. When the control valve 3 is opened and the atmosphere of the spring 15 is connected to the vacuum pressure, the pressure approaches the vacuum. When a pressure difference occurs on both sides of the piston 13, the piston 13 moves to the right. Since the vent hole 24 remains open and the leak hole inlet 16 is at least slightly open (about several tens of microns),
Gas flows inside the leak hole 17 and is sucked into the vacuum source 6. In this state, the driving path atmosphere foreign matter 18 is sucked into the cylinder 14 to prevent the foreign matter and the like from being scattered outside the cylinder. When the holding component 7 applies a force for gripping the substrate 1, the stopper 19 that transmits the force from the drive rod 22 contracts the small spring 21 as shown in FIG. 2, and the leak hole inlet 16 between the piston 13 and the valve 20 closes. Start to open. When the leak hole inlet 16 is further opened, the gas flowing in the leak hole 17 increases, and the value of the pressure sensor 5 approaches the atmospheric pressure from the state when the piston 13 was at the left end. When the piston 13 further moves to the right, the substrate holding unit 7 stops while keeping the substrate 1 pressed.

If the substrate 1 cannot be held,
Even if the piston 13 operates, the leak hole inlet 16 does not change. Thereby, the value of the pressure sensor 5 shows a different value depending on the holding state, and the detection of the substrate 1 becomes possible. Further, if the left end of the mechanism cannot be moved due to a failure of the mechanism itself, the pressure value does not reach the leak state even after a certain period of time, so that the abnormality can be detected.

FIG. 5 shows an example of the sensor output 25 from the holding operation start 29 to the holding operation end 30 in the relationship between the piston position 27 and the pressure 28. The threshold value 26 is set between the substrate-less driving pressure 32 and the substrate holding driving pressure 31 to enable the holding detection.

By having a throttle 23 capable of adjusting the amount of leak, a pressure 28 for driving and a suction flow rate of air for sucking foreign matter 18 generated between the holding table 12 and the driving rod 22 are adjusted. I can do it.

Embodiment 2 is shown in FIG.

The valve 20 attached to the drive rod 22 has a gap 33 between the piston 13 and the piston 13 so that a small leak can occur. As a result, the valve 20 moves in the direction away from the piston 13, the resistance caused by the gap 33 decreases, and the pressure 28 measured by the pressure sensor 5 approaches the atmospheric pressure. By detecting the fluctuation of the pressure 28, the holding state can be detected.

The contact surfaces of 20 and 13 may be tapered to further vary the pressure.

The leak hole 17 may be replaced by providing a gap between the drive rod 22 and the piston 13.

[0027]

According to the substrate holding mechanism of the present invention, since the substrate surface to be held is held at the end face with high reliability without being contaminated, the holding state can be detected by a change in pressure.

Further, since the drive and the detection can be performed only by the vacuum path, the structure is simple, and the reliability of the drive and the detection is high even when used in a portion where the movement is frequently repeated.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram (side view) of a substrate holding device that is Embodiment 1 of the present invention.

FIG. 2 is a schematic configuration diagram (side view) of a substrate holding state in Example 1.

FIG. 3 is a schematic configuration diagram (side view) of Conventional Example 1.

FIG. 4 is a schematic configuration diagram (side view) of Conventional Example 2.

FIG. 5 is an explanatory diagram of a pressure change of the substrate holding device according to the first embodiment of the present invention.

FIG. 6 is a schematic configuration diagram (side view) of a substrate holding device that is Embodiment 2 of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Suction plate, 3 ... Control valve, 4 ... Suction port, 5 ... Pressure sensor 6 ... Vacuum source, 7 ... Holding component, 8 ... Holding component, 9
… Drive source, 10… sensor, 11… wiring, 12…
Holder, 13: Piston, 14: Cylinder 15: Spring, 16: Inlet of leak hole, 17: Leak hole, 18: Foreign matter in drive path, 19: Stopper, 20
… Valve, 21… Small spring, 22… Drive rod, 23…
Aperture, 24 ... vent hole, 25 ... sensor output, 26 ...
Threshold value, 27 position, 28 pressure, 29 start of holding operation, 30 end of holding operation 31 ... substrate holding driving pressure, 32 ... driving pressure without substrate, 33 ... gap.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toba Hayami 3-3-2 Fujibashi, Ome-shi, Tokyo Within Hitachi Tokyo Electronics Co., Ltd. (72) Inventor Takashi Iwata 3-2-2, Fujibashi, Ome-shi, Tokyo Hitachi East Inside the Tokyo Electronics Co., Ltd. (72) Inventor Takeshi Tajima 3-3-2 Fujibashi, Ome-shi, Tokyo Inside the Hitachi Tokyo Electronics Co., Ltd.

Claims (1)

[Claims] 1. A work holding mechanism having a fixed holding part and a movable holding part movable forward and backward with respect to the fixed holding part, the work holding mechanism holding a work by these holding parts, wherein the work holding mechanism is connected to a vacuum source. A cylinder in which a piston that divides a vacuum pressure chamber and an atmospheric pressure chamber is slidably provided; and a drive rod that connects the movable holding component and the piston and transmits movement of the piston to the movable holding component. A vent hole formed in the cylinder in communication with the atmospheric pressure chamber to allow air near the work to flow in; a leak hole formed in the piston to communicate the vacuum pressure chamber with the atmospheric pressure chamber; A valve fixed to a predetermined position of the drive rod, and configured to change an opening amount of the leak hole at the atmospheric pressure chamber side entrance according to a relative movement of the drive rod and the piston via a spring; Workpiece holding mechanism, characterized in that the.