JPH0151413B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for immersing plate-like objects such as semiconductor wafers, photomasks, ceramics, etc., which do not allow even minute scratches or stains on their surfaces, into a fluid using a fluid such as air. This relates to an air holding device for floating in a non-contact state and transporting in a floating state as necessary.

[Prior Art] Conventionally, as a conveyance device that uses a high-pressure fluid such as high-pressure air to float and convey a plate-shaped object such as a semiconductor wafer in the fluid without contact, there is one that utilizes the Bernoulli effect. be.

For example, US Patent No. 3438668; 4009785;
4029351; 3523706; 4002254; 3993301;
3539216; 4474397; 4566726; USSR Patent No.
257628; IBM Technical Disclosure, Bulletin
There is RDColes, Vol.22 Jan.1980, Page 3370.

All of these examples are conveyors that utilize only the Bernoulli effect, that is, the correlation between fluid velocity and pressure.

Typical examples thereof are shown in FIGS.

A fluid inlet port 1 connected to a high-pressure fluid generator is provided on the upper surface of these conveyors D and E, and a closed port 1 is provided on the lower surface of the conveyor device D and E in close proximity to and opposite to the plate-shaped object G to be conveyed. A flat surface 11, 12 is provided. These planes 11 and 12 are provided with nozzles 13 and 14 that eject fluid.

High pressure fluid C spouted from these nozzles 13 and 14
passes through the gap between the plate-shaped body G and the planes 11 and 12,
Released to the outside. During this time, static pressure decreases in the gap due to the speed of the passing fluid due to the Bernoulli effect, and the plate-shaped body G is attracted. plane 11,1
2 and the plate-shaped body G becomes smaller, the plate-shaped body G is formed on the planes 11 and 12 due to the cushioning effect of the fluid.
prevent contact.

[Problem that the invention is trying to solve]

As described above, the conventional conveying device is inefficient because it has only the suction effect due to the Bernoulli effect and the repulsion effect due to the cushioning effect of the fluid. Since the nozzles 12 are much larger than the nozzles 13 and 14, the fluid passing through the gap between the flat surfaces 11 and 12 and the plate-like body G is not uniform, and may cause vibrations to the plate-like body G or damage due to contact with the flat surface. There was a drawback of adding .

[Purpose of the invention]

The present invention has been made in order to solve these drawbacks, and it is an object of the present invention to provide an air retaining device that efficiently generates suction force and repulsive force, and in which the plate-like bodies do not come into contact with each other under any circumstances.

[Means to solve the problem]

The air retaining device according to the present invention has an upper part 2 provided with a fluid inlet 1 into which high-pressure fluid C flows, and a peripheral wall part 3 formed around the upper part 2 and facing downward. When the distance from the plate-like body G approaching the lower end of the section 3 increases, the high-pressure fluid C flowing in from the fluid inlet 1 sucks the plate-like body G due to the negative pressure effect caused by the ejector effect, and the distance increases. A bowl-shaped base B having a space forming a cushion chamber 4 that separates the plate-like body G by a positive pressure action accompanying a pressure chamber type air action effect caused by the high-pressure fluid C flowing in when B is at the lower end of the peripheral wall portion 3,
The high-pressure fluid C flowing outward between the plate-like body G and the plate-like body G attracts the plate-like body G due to negative pressure caused by the Bernoulli effect due to the speed increase, and the high-pressure fluid C flowing outward also causes the plate-like body to It has a wide working surface 5 which is continuous in the direction of the peripheral wall 3 and which is prevented from coming into contact with the shaped body G, and the fluid inlet 1 is arranged at right angles to the working surface 5.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail below with reference to the drawings, but the air retaining device of the present invention is not limited to these examples.

1 and 2 respectively show an air retaining device A of the present invention.

The lower part of the bowl-shaped base B, which has a downwardly facing peripheral wall 3 formed around the upper part 2 provided with the fluid inlet 1 through which the high-pressure fluid C flows, is opened, and the lower end of the peripheral wall 3 has a wide width and the peripheral wall part Continuous in 3 directions. An actuating surface 5 is provided to form an air retention device A.

A high-pressure fluid supply device such as a blower or a compressor is connected to the fluid inlet 1 via a pipe (not shown).

A high-pressure fluid C is sent by a fluid supply device through a pipe toward a plate-like object G, which is a conveyed object such as a wafer or a photomask, which is placed close to the operating surface 5 of the air holding device A. It is ejected from the inlet 1 into the cushion chamber 4 formed inside the base B, and is discharged to the outside through the gap between the operating surface 5 and the plate-shaped body G.

During this time, if the gap between the operating surface 5 and the plate-like body G is large, the space formed by the operating surface 5 and the plate-like body G is
The cushion chamber 4 functions as the vacuum chamber 10 of the ejector, and the fluid inlet 1 functions as the nozzle 8 of the ejector.

Therefore, when the distance between the operating surface 5 and the plate-shaped body G is large, the air retaining device A functions as an ejector, and the pressure in the cushion chamber 4 is reduced.

At the same time, the flow velocity of the fluid passing through the space between the actuating surface 5 and the plate-shaped body G increases, and the static pressure in the space decreases due to the Bernoulli effect, both of which generate a large suction force against the plate-shaped body G.

On the other hand, when the distance between the plate-shaped body G and the actuating surface 5 to which it is sucked becomes smaller, the cushion chamber 4 performs the same function as a pressure chamber type air action of a hovercraft, and the pressure in the cushion chamber 4 increases. at the same time,
The fluid passing through the space also produces a cushioning effect, and together they generate a repulsive force against the plate-like body G, preventing the plate-like body G from coming into contact with the working surface 5.

As mentioned above, the air holding device A according to the present invention
It has an ejector effect and a Bernoulli effect as a suction function, and a pressure chamber type air action effect and a cushion effect due to a fluid flow as a repulsion function.

FIG. 6 shows that the air retaining device A of the present invention has a plate-shaped body 6.
The relationship between the pressure generated on the plate-shaped body G during suction suspension and the distance from the center of the air holding device A is expressed using the distance h between the operating surface 5 and the plate-shaped body G as a parameter.

FIG. 7 shows the above-mentioned relationship of the conventional conveyance device D that utilizes only the Bernoulli effect.

P ₀ ...Fluid supply pressure P...Pressure on plate G r...Distance from the center of plate G h...Distance between plate G and operating surface 5 d...Aperture of fluid inlet 1 D=4d The fluid supply amounts in FIGS. 6 and 7 are the same.

Parameter h/D in Figures 6 and 7
The values of h/d and h/d are values that produce the maximum attractive force and repulsive force acting on the plate-shaped body G, respectively.

As shown in FIG. 6, in the air holding device A of the present invention, the cushion chamber 4 performs a function equivalent to the vacuum chamber 10 of the ejector in the range of r/D = 0.24 to 0.45, and It performs a function equivalent to a plane that generates the Bernoulli effect in a range.

The maximum suction force acting on the plate-like body G is h/D=
0.02, and the lowest value of the pressure at that time reaches P/P ₀ =-1.05 at r/D = 0.35.

On the other hand, as shown in FIG. 7, in the conventional conveying device D that uses only the Bernoulli effect, the maximum value of the suction force acting on the plate-like object G occurs at r/d=0.08, and the value is r/d = 2.0, P/P ₀ = -0.6
It is.

Furthermore, the maximum value of the suction force acting on the entire plate-shaped body G is 1.4 times as large as that of the conventional conveying device using only the Bernoulli effect in the air retaining device A of the present invention.

On the other hand, the maximum repulsive force acting on the plate-shaped body G is as shown in FIG. 6 for the air holding device A at h/L=0.005, and as shown in FIG. 7 for the conventional conveyor. As shown, the repulsive force acting on the entire plate-shaped body G is 1.3 times larger in the air retaining device A of the present invention, which occurs at h/d=0.02.

As mentioned above, it can be seen that the air holding device A of the present invention has much better performance than the conventional conveying device.

Further, as shown in FIG. 8, the shape of the operating surface 5 may be planar, curved, upward, or downward depending on the shape of the plate-like body G.

〔Effect of the invention〕

As described above, the present invention can efficiently suction and suspend plate-shaped objects such as semiconductor wafers, photo masks, and glass without contact, compared to conventional conveying tools that utilize only the Bernoulli effect. It is possible to provide an excellent air retention device.

[Brief explanation of drawings]

FIG. 1 shows a side sectional view of the air retaining device of the present invention, and FIG. 2 shows a top plan view thereof. FIG. 3 shows an explanatory diagram of the structure of the ejector. 4 and 5 show side cross-sectional views of conventional carriers.
FIGS. 6 and 7 show pressure diagrams of the air retaining device of the present invention and the conventional carrier, respectively. FIG. 8 shows a side cross-sectional view of another embodiment of the invention. In the figure, 1 - fluid inlet, 2 - upper part, 3
~ Peripheral wall portion, 4 ~ Cushion chamber, 5 ~ Operating surface, 8 ~
Nozzle, 9 - Diffusion user, 10 - Vacuum chamber, 1
1, 12 - plane, 13, 14 - nozzle, A - air holding device, B - base, C - high pressure fluid, D, E - conveyor, G - plate-shaped body.

Claims (1)

[Claims] 1 A plate-shaped body that approaches the lower end of the peripheral wall 3 by an upper part 2 provided with a fluid inlet 1 into which high-pressure fluid C flows, and a peripheral wall 3 formed around the upper part 2 and facing downward. When the distance from the high-pressure fluid C that flows in from the fluid inlet port 1 to G becomes large, the plate-shaped body G is sucked by a negative pressure effect due to the ejector effect, and when the distance from the high-pressure fluid C that flows to the plate G becomes small, the high-pressure fluid flows in. The base B includes a bowl-shaped base B having a space forming a cushion chamber 4 that separates the plate-like body G by a positive pressure action accompanying the pressure chamber type air action effect caused by C.
At the lower end of the peripheral wall portion 3, the high-pressure fluid C flowing outward between the plate-shaped body G and the plate-shaped body G is sucked by a negative pressure effect due to the Bernoulli effect due to the speed increase, and the high-pressure fluid C flowing outward between the plate-shaped body G and It has a wide working surface 5 that is continuous in the direction of the peripheral wall 3 and is prevented from contacting the plate-shaped body G by the high-pressure fluid C, and the fluid inlet 1 is provided at right angles to the working surface 5. Air holding device A.