JPS6387439A - Holding device for plate-like body - Google Patents

Abstract

PURPOSE:To hold a plate-like body in a non-contact manner by means of a high hold force, by providing a holding body, having a holding surface, which serves to form a plane-like gap between the plate-like body and the holding body. CONSTITUTION:A valve device 8D of a fluid feed source 8 and a valve device 12D of a fluid suction source 12 are brought into an opening state to actuate a holding mechanism. When, with this state, a device frame 13 is lowered and is caused to approach a plate-like body 1, since a holding body 2 is movable to a device frame 13 through the force of a spring-like body 14, a proper gap (h) is automatically formed and held between a holding surface 2A of the holding body 2 and an upper surface 1A of the plate-like body 1 by means of a fluid force. When the held plate-like body 1 is placed on a plane, only suction of fluid is stopped, and a device frame 13 is raised. After the plate-like body 1 is separated from a device, the feed of fluid is also stopped.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a holding device for a plate-shaped body such as a semiconductor substrate, and particularly relates to a holding device for a plate-shaped body such as a semiconductor substrate, and in particular, a device for holding a plate-shaped body such as a semiconductor substrate. , relates to a device for holding a plate-like object in a non-contact state.

[Conventional technology]

Conventionally, as a device for holding a plate-shaped body by suction force of fluid, a suction pipe and a discharge pipe provided around the suction pipe are combined, as shown in Japanese Patent Laid-Open No. 51-40343, for example. There is a device that holds the plate-shaped body at the tip of the suction pipe and the discharge pipe without contact by allowing fluid to flow in and out from the suction pipe and the discharge pipe.

[Problem that the invention seeks to solve]

In the above conventional technology, the area where the fluid force acts on the plate is limited to the inlet of the suction pipe and the outlet of the discharge pipe, and the flow rate in the discharge pipe changes with respect to the displacement in the direction perpendicular to the surface of the plate which is held in a non-contact manner. Since the change is small, the holding force against the plate-like body, especially the holding restoring force, is small, so there is a problem that holding stability is lacking. Furthermore, in order to obtain a larger holding force, the outlet area of the suction pipe and discharge pipe must be expanded.
Since it is necessary to set a small gap between the tip of the tube and the plate-like body, when the plate-like body is grabbed by the device or when the plate-like body held is released to a predetermined place, the gap between the plate-like body or the release location is It was necessary to accurately position the device so that there was an appropriate gap between the flat surface of the plate and the device.6 If the positioning accuracy is poor, for example, when grasping, the plate-like object and the device (
Problems arise, such as the distance from the tip of the tube being too large to lift the plate-like object, or conversely, the device coming into contact with the plate-like object.

The present invention is capable of holding a plate-like body with a strong holding force without contact, and when the plate-like body is gripped by the device or released, the device does not come into contact with or cannot grip the plate-like body. It is an object of the present invention to provide a holding device for a plate-shaped body that does not cause the plate-like body to sag.

[Means for solving problems]

The above-mentioned object of the present invention is to provide a device for holding a plate-shaped body in a non-contact manner by fluid force, and to provide a holder having a holding surface for forming a planar gap between the plate-shaped body and the holder. a fluid ejecting part provided on the holding surface of the retainer and having a throttle that generates pressure equal to or higher than atmospheric pressure against the plate-like body facing the holding surface; and a holding body located around the fluid ejecting part. a fluid suction section that is provided on the holding surface of the plate and generates pressure below atmospheric pressure on the plate-like body; a device frame for installing the holding body; and a device frame that allows the holding body to be moved relative to the device frame. This is achieved by providing an elastic support device for elastic support.

[Effect]

The fluid suction section located around the fluid ejection section reduces the average pressure within the gap between the holding surface and the plate-like body to below atmospheric pressure by suctioning the fluid. This negative pressure supports the weight of the plate-shaped body. On the other hand, the fluid jet section supplies pressurized fluid to the gap between the holding surface and the plate-like body through the throttle. As a result, the pressure within the gap in this area decreases as the gap distance increases, and increases as the gap distance decreases. For this reason,
Due to the interaction with the negative pressure obtained by the fluid suction section, the plate-shaped body is supported without contact with the holding surface while maintaining a constant minute gap. Also, when the device grips the plate or releases it to a predetermined location: - Because the holding body is movable relative to the device frame, when the device is brought sufficiently close to the plate or the plane of the release location; , the gap distance between the plate-shaped body and the holding plane is automatically maintained at an appropriate value by the above-mentioned fluid force, and the device is brought into contact with the plate-shaped body;
Alternatively, it is possible to prevent failures such as not being able to grasp the plate-like object because the gap is too wide.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show an embodiment of the plate-like object holding device of the present invention, and in these figures, numeral 1 indicates a plate-like object, such as a semiconductor wafer, which is to be held in a non-contact manner. 2
1 is a holder for the plate-like body 1, and three holders 2 are each mounted on the device frame 13 via a spring-like body 14.

A holding surface 2A is formed on each holding body 2,
A gap 3 is formed between each holding surface 2A and the upper surface IA of the plate-like body 1, with a gap h separated therefrom. The holding surfaces 2A of the three holding bodies 2 have the same structure, and each holding surface 2A has a fluid suction part that sucks the gas in the gap 3 and keeps the average pressure in the gap 3 below the external pressure. and a fluid jetting portion for introducing pressurized fluid into the gap 3. The fluid suction section includes an annular groove 9 provided on the outer periphery of the holding surface 2A, and this groove 9 is connected to a fluid suction source 12 through a fluid suction passage 10 and a conduit 11 in the holding body 2. Further, the fluid ejecting portion is attached to the holding surface 2A.
It is equipped with an opening 4 and a diaphragm 5 provided in the center of the
This restriction 5 is connected to a fluid supply source 8 through a fluid passage 6 and a line 7 in the holder 2 . In addition, the device frame 13
A guide 15 is provided around the plate member 1 to prevent movement of the held plate member 1 in the plane direction.

The configuration of an example of the fluid supply source 8 and the fluid suction source 10 described above will be explained using FIG. 3 and FIG. 4, respectively. As shown in FIG. 3, the fluid supply source 8 includes a pressure pump 8A,
It is composed of a drive motor 8B, a pressure regulator 8C that adjusts the pressure of the fluid pressurized by the pressure pump 8A, a valve device 8D that turns on and off the supply of fluid, and a filter 8E that removes dust. There is. Further, as shown in FIG. 4, the fluid suction source 12 includes a vacuum pump 12A, its drive motor 12B, a variable throttle valve 12C that opens the pipe line 11 to the atmosphere, and a valve system 5R that turns on and off fluid suction.
12D, and the negative pressure can be adjusted by adjusting the throttle of the variable throttle valve 12G.

Next, the operation of one embodiment of the above-mentioned apparatus of the present invention will be described.

Prior to explaining the operation, the principle for holding the plate-shaped body 1 in a non-contact manner will be explained.

In FIG. 5, when the fluid suction source 12 is activated, fluid is suctioned from the annular groove 9 through the conduit 11 and the fluid suction hole 10, and the pressure inside the annular groove 9 is reduced to below atmospheric pressure. On the other hand, the pressurized fluid supply source 8, which is maintained at a high pressure by the pressure within the annular groove 9, supplies pressurized fluid to the pipe line 7.
The pressurized fluid is supplied from the pressurized fluid supply hole 6 to the gap 3 through the throttle 5, and a pressure higher than atmospheric pressure is applied to this part. At this time, the pressure within the gap 3 and the force acting on the plate-like body 1 calculated from this pressure are theoretically as follows.

Now, when the gap of the gap 3 is set to be sufficiently small, it can be assumed that the flow in the gap 3 is an isothermal two-layer flow in which viscous force is dominant compared to inertial force. At this time, the following equation and boundary conditions hold for the flow within the gap 3 using the coordinate system and symbols shown in FIG.

For the clearance r, h≦r≦rO, P=Pc at r= rx, P=Pv at r
= ro - (2) For the clearance r&≦r≦rb, P=Pv at r=ra, P=Pa at r=r
b - (3) where, r: Coordinate measured from the center of the holder 2 in the direction in which the gap 3 extends h: Distance of the gap 3 P: Pressure within the gap 3 rl: Radius of the opening 4 ro: Annular groove 9 outer radius of the holding surface 2A surrounded by, inner radius of the annular groove 9 r & : outer radius rb of the annular groove 9 : radius Pc of the holding surface 2A of the holding body 2 : pressure P in the sealing part 4 : annular groove 9 Internal pressure Pa: atmospheric pressure For the equation of the flow (pressure) within this gap 3, the gas mass flow rate mR passing through the throttle 5 installed in the pressurized fluid supply hole 6 is, where: CD niorifice throttle flow coefficient (Co20, 85 for air) R: Gas constant T: Absolute temperature of gas Ps: Pressure of gas supplied to pressurized fluid supply hole 6 K:
The specific heat ratio of the gas, and the gas mass flow rate m, flowing within the gap 3 where r1≦r≦ro is, where μ: viscosity coefficient of the gas, and these gas mass flow rates mR, mh are: The following continuity conditions are imposed.

m R” m h...
...(6) Above, equations (1) to (6) are the basic equations for the flow within gap 3, and by solving them,
The pressure within gap 3 is determined. Based on the determined pressure within the gap 3, the suction force F (positive upward) acting on the plate-like body 1 is expressed as follows.

F= −f (P−Pa)2πrdr==−πrx”
(Pc Pa) f (P-Pa)2zrdr l -? C(ra"-ro")(Pv-P,)f(P-
Pa) 2 x r d r ・-n>r & Here, the solutions of equations (1) to (3) for pressure P are, however, here pc is unknown, and this Pc is expressed by equations (4) to (6)
More determined.

FIG. 7 shows the results of calculating the suction force F acting on the plate-like body 1 by changing the interval of the gap 3 from the above equations (]) to (7). The operation of one embodiment of the apparatus of the present invention described above will be explained with reference to this diagram as follows.

Now, the spacing of the gap 3 is set to the design gap VAha, that is, the suction force and the weight of the plate-like body 1 are balanced when the plate-like body 1 is in the position shown by the solid line in FIG. shall be. At this time, when the plate-shaped body 1 moves to the position shown by the broken line in FIG. 5 and the interval of the gap 3 exceeds the set gap interval h4 and increases to hb, the suction force is applied to the plate as shown in FIG. It becomes larger than the weight of the shaped body 1. Therefore, a restoring force acts on the plate-shaped body 1 located at the position shown by the broken line in FIG. 5 in the direction of returning it to the position of the gap 74 ha, which is the design point. Similarly, even when the gap 3 becomes smaller than the design point gap h4, a restoring force acts on the plate 1 in the direction of returning its position to the design gap h4. The plate-shaped body 1 is stably supported floating in a non-contact manner across the holding surface 2A of the holding body 2 and the gap 3.

Further, at this time, the annular groove 9 that is maintained at negative pressure is provided in an annular shape so as to surround the opening 4 (so that the annular groove 9 is kept under negative pressure).
All the fluid that has flowed into the gap 3 is sucked and collected into the annular shape 9 and is not ejected to the outside. On the contrary, holding body 2
Outside air flows into the annular groove 9 from the outer periphery of the annular groove 9.
The size of the negative pressure inside is about 200 to 300 m water column,
Unlike the conventional holding device using the Bernoulli principle, the interval between the gaps 3 can be set small, so the flow rate of the fluid flowing into the gaps may be small.

In the above-mentioned embodiment, positive pressure is generated at the center of the plate-like body 1 in the gap between the holding surface 2A of the holding body 2 and the plate-like body t, and negative pressure is generated around the central part of the plate-like body 1. can be reliably held in a non-contact state with respect to the holder 2. Therefore, as shown in FIG. The plate-like body 1 can be held in a non-contact manner no matter how the posture of the body 2 is changed.

Next, with reference to FIG. 8, the operations when the plate-like body 1 is gripped and released by the apparatus of the present invention will be explained.

First, the case where the plate-shaped body 1 placed on the plane 16 is gripped by the apparatus of the present invention will be explained. A recess 17 is provided in the flat surface 16 to prevent the guide 15 fixed to the device frame 13 from coming into contact with the flat surface 16 when the device frame 13 is brought close to the flat surface 16. First, the valve device @8D of the fluid supply source 8 and the valve device 12D of the fluid suction source 12 are opened to operate the holder end.

In this state, when the device frame 13 is lowered and brought close enough to the plate-like body, the holder 2 can be moved relative to the device frame by the spring-like body 14, so that the holder 2 is moved by the above-mentioned fluid force.
An appropriate gap is automatically formed between the holding surface 2A and the upper surface IA of the plate-like body 1. That is, plane 1
6 or even if the positioning accuracy of the device with respect to the plate-like body 1 is poor, failures such as the device coming into contact with the plate-like body 1 or being unable to grip the plate-like body 1 because the gap is too large will not occur.

If the device is brought close to the plate-like body 1 with the holding mechanism activated, the plate-like body 1 will move to the flat surface 16 before it gets close enough.
may fly away and be held by the device. At this time, there is a possibility that the plate-shaped body 1 comes into contact with the holding surface 2A due to uneven contact.

In order to prevent this, the apparatus frame 13 is brought close to the plate-shaped body 1 while only the fluid supply by the fluid supply source 8 is operated and the fluid suction by the liquid suction source 12 is stopped, and the holding surface 2 is
After a sufficiently small gap is formed between A and the upper surface IA of the plate-shaped body 1, the procedure of activating fluid suction may be taken.

Next, when placing the held plate 1 on the flat surface 16, the device frame 13 is brought sufficiently close to the flat surface 16 to bring the plate 1 into contact with the flat surface, as in the case of grasping the plate 1. Due to the spring-like body 14, even if the device frame 13 is brought sufficiently close to the flat surface 16, the holding surface 2A of the holding body 2 does not come into contact with the plate-like body 1. After this, first, only the suction of the fluid is stopped, and the device frame 13
to rise. After the plate-like body 1 is detached from the device,
The fluid supply is also stopped. By keeping the fluid supply in operation when the device frame 13 is raised, the holder 2 does not come into contact with the plate-shaped body 1. As a result, the plate-like object can be handled accurately and without contact.

FIG. 9 shows another embodiment of the apparatus of the present invention, in which the same reference numerals as in FIG. 1 represent the same or corresponding parts. In this embodiment, the holder 2 is supported from the outer periphery of the device frame 13 by a spring-like body 14.

According to this embodiment, since the spring-like body 14 is not provided near the center of the device frame 13, the three holding bodies 2 can be provided close to each other, and the plate-like body 1 having a smaller area can be retained.

FIG. 10 shows still another embodiment of the apparatus of the present invention, and in this figure, the same reference numerals as in FIG. 1 indicate the same or corresponding parts. In this embodiment, a flange 2B is provided on the upper part of the holder 2 in the embodiment of the apparatus of the present invention shown in FIG. The spring stiffness of the spring-like body 14 supporting the holder 2 is weaker than that of the device shown in FIG. This is to guide the material so that it does not come into contact with the inner surface of the hole. If the plate-shaped body 1 to be held is not a wafer and dust generation and contamination of the plate-shaped body due to contact between the holder 2 and the device frame 13 are not a problem, the spring-shaped body 14 of the device shown in FIG. When the plate-like body 1 is held, the holder 2 is lowered by the weight of the plate-like body 1, and the flange 2B comes into contact with the device frame. Flange 2 of three holding bodies 2
The holding surfaces 2A of the three holding bodies 2 are formed so as to be on the same plane when each of the holding bodies 2 B comes into contact with the device frame 13.

According to this embodiment, since the spring rigidity of the spring-like body 14 is weak, even if the device frame 13 is brought too close to the plate-like body 1 placed on a flat surface, the holder 2 is not pressed against the plate-like body 1. There is no possibility that the force overcomes the above-mentioned fluid force and the holding body 2 comes into contact with the plate-like body 1. Furthermore, when holding the plate-shaped body 1, since the three holding surfaces 2A are on the same plane, each holding surface 2A
Since the gaps between the holding mechanism and the plate-shaped body 1 are parallel and the same amount, the function of the holding mechanism is not impaired. Non-parallel clearances cause uneven contact, and uneven spacing between the three holding surfaces leads to a reduction in the load carrying capacity, and hence in the load capacity as a whole.

FIG. 11 shows yet another embodiment of the apparatus of the present invention, in which the same reference numerals as in FIG. 1 represent the same or corresponding parts. In this embodiment, the entire device frame 13A, in which three holding surfaces 2A are fixedly provided, is supported by a spring-like body 14 on a support ring 13B of the device frame.

In this embodiment, since the three holding surfaces 2A are on the same plane, the function of the holding mechanism is fully exhibited. Furthermore, since there is only one spring support portion, the structure is simplified.

〔Effect of the invention〕

As explained above, according to the present invention, the plate-like body can be held with strong holding force without contact, and when the plate-like body is held and released, contact between the device and the plate-like body is prevented, A plate-like object can be handled reliably.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional front view of one embodiment of the device of the present invention, FIG. 2 is a bottom view thereof, FIG. 3 is a diagram showing the configuration of an example of a fluid supply source used in the present invention, and FIG. A diagram showing the configuration of an example of a fluid suction source used in the invention, FIG. 5 is a partial cross-sectional view of the vicinity of the holding surface provided to explain the holding operation of the plate-shaped body by the device of the invention, and FIG. FIG. 7 is an explanatory diagram showing the dimensional relationship, FIG. 7 is a characteristic diagram of holding operation of a plate-shaped body by the apparatus of the present invention, and FIG.
... Plate-shaped body, 2... Holding body, 2A... Holding surface, 4.
...Opening part, 5... Throttle mechanism, 8... Fluid supply source,
9... Groove, 12... Fluid suction source, 13... Device frame, 14... Spring-like 7. 1 12δ
Morph motor gE-ful 4c 12c
・Ashino valve SC-, pressurized moromig +2A-J size-
7012...Mockery C1 Figure No. qrozaki c8 Kuman 9 concave

Claims (1)

[Claims] 1. A holding surface for forming a planar gap between the plate-shaped body and the plate-shaped body in a device that uses fluid force to hold the plate-shaped body in a non-contact manner and transport it to another location. a holder, a fluid ejecting section provided on a holding surface of the holder, and equipped with a throttle that generates a pressure equal to or higher than atmospheric pressure against a plate member facing the holding surface; and a holding surface of the holder. a fluid suction section that generates a pressure below atmospheric pressure against the plate-shaped body facing the holding surface; a device frame for installing the holding body; 1. A holding device for a plate-shaped body, comprising an elastic support device that movably supports a holding body. 2. The plate-shaped body according to claim 1, wherein the elastic support device supports the holder so as to be movable in a direction perpendicular to its holding surface and in a direction away from the wafer it holds. holding device. 3. Claim 1, characterized in that the elastic support device supports the holding body movably in a direction in which the holding surface of the holding body is inclined.
A holding device for a plate-shaped body as described in 2. 4. Holding a plate-like body according to claim 2 or 3, wherein the elastic support device is installed on the device frame via a spring-like body such as a plate spring or a coil spring. Device.