JPH0270617A - Wafer carrying device - Google Patents

Abstract

PURPOSE:To make it possible to carry a water without generation of dust and improve cleanliness by applying direct current voltage on electrodes lengthwise laid on a carrying base, and actuating electric force in the center direction on the wafer deviated from the center line of the carrying base. CONSTITUTION:This wafer carrying device is constituted so as to carry a wafer in floating condition from a carrying base 20 by blowing air obliquely on the carrying base 20. Dielectric layers 21a, 22a made from ceramics are formed on the upper face of belt-shaped electrodes 21, 22 made from tungsten. The electrodes 21, 22 having a width size equivalent to a half width of the carrying base 20 are laid on the upper face of the carrying base 20, symmetrically to the center line. The wafer 24 is given floating force and carrying force by air flow 25 obliquely blown from blowout holes 23, and carried. When the wafer 24 is deviated in the widthwise direction X, X of the carrying base 20 against the center line of the carrying base 20, electric force Fx in the center line direction is actuated on the wafer 24.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a wafer transfer device.

The wafer transfer device is required to first have a structure that allows the wafer to be transferred without causing dust generation, and secondly to have a structure that allows stable transfer.

[Conventional technology]

Figures 8 (A), (B), and (C) show one example of a conventional wafer transfer device.
No example given.

The wafer 1 is supported by airflows 4 blown out from a large number of diagonal air blowing holes 3 of the transfer substrate 2, and is transferred in the Y direction while floating above the upper surface of the transfer substrate 2.

Guides 5 and 6 are provided to restrict displacement of the wafer 1 in the X and X2 directions beyond a predetermined value.

FIG. 9 (A>(B) and (C)) shows another example of a conventional wafer transfer device.

The wafer 1 is supported by an air flow 12 from an air blowing hole 11 of the transfer substrate 10 and is transferred in the Y direction.

The air blowing hole 11 is inclined toward the center of the transfer substrate 10, as shown in FIG.

[Problem to be solved by the invention]

According to the apparatus shown in FIG. 8 above, the wafer 1 and the transfer substrate 2
Although there is no contact with the guide 5 or 6, the wafer 1 may come into mechanical contact with the guide 5 or 6. In this case, dust is generated.

In principle, the device shown in FIG. 9 satisfies both the first and second requirements.

However, in order to bring the wafer 1 closer to the center of the transfer substrate 10, it is actually necessary to form the hole 11 into a complicated shape, which is difficult to process.

SUMMARY OF THE INVENTION An object of the present invention is to provide a wafer transfer device that enables transfer without causing dust generation and is easy to manufacture.

(Means for Solving the Problems) The present invention provides a wafer transfer device that blows air obliquely onto a transfer substrate to float a wafer above the transfer substrate and transfer the wafer. The electrodes are arranged in a longitudinal direction on the transfer substrate symmetrically with respect to the center line of the transfer substrate, and a DC voltage is applied between the F distribution electrodes, so that the wafer is aligned with respect to the center line of the transfer substrate. When the wafer is deflected in the width direction of the transfer substrate, an electric force is applied to the wafer in the direction of the center line.

[Effect]

Since a DC voltage is applied to the electrodes arranged in the longitudinal direction, an electric force in the direction of the center line acts on the wafer that is deviated from the center line of the transfer substrate.

This electrical force guides the wafer.

(Example) In FIG. 1, FIG. 2, and FIG. 3, 20 is a transfer board, which is made of an insulating material.

21 and 22 are band-shaped electrodes made of tungsten, respectively;
The electric layers 21a and 22a made of ceramic are formed on the upper surface.

The strip-shaped electrodes 21 and 22 have a width corresponding to half the width of the transfer substrate 200, and are arranged symmetrically on the upper surface of the transfer substrate 20 with respect to its center line CL.

Reference numeral 23 denotes a large number of air blowing holes, which are formed on the transfer substrate 20 and electrodes 21 and 22 so as to be inclined in the wafer transfer direction shown by arrow Y.

As shown in FIG. 1, this air blowing hole 23 is not inclined in the width direction of the transfer substrate 20.

Further, the shape of the hole 23 is not complicated. Therefore, machining of the hole 23 is relatively easy.

The wafer 24 is moved by an air stream 25 blown obliquely from the hole 23.
A floating blade and a conveying force are applied to the substrate 20, and the substrate 20 is conveyed in the direction of arrow Y while floating above the upper surface of the conveying substrate 20.

A DC voltage is applied between the electrodes 21 and 22 by a DC power supply 26.

The wafer 24 is electrically conductive, and the part of the floating wafer 24 facing the electrode 21 and the electrode 21 are -
A portion of the wafer 24 facing the electrode 22 and the electrode 22 constitute another capacitor.

There are electric lines of force 27 between the wafer 24 and the electrodes 21,22.
An electric field is formed.

As shown in FIG. 4, the wafer 24 is located at the center of the transfer substrate 20 (indicated by the dotted chain line in FIG. 2), and the wafer 24
When the deviation dimension with respect to the center line CL of 4 is zero,
The electric field is formed as shown in the figure.

The lines of electric force between the outer part of the electrode 21 and the peripheral edge of the wafer 24 are as shown by 27a, and the lines of electric force between the outer part of the electrode 22 and the peripheral edge of the wafer 24 are shown by 27b.
It becomes as shown in .

The electric lines of force 27a and 27b are symmetrical, and the wafer 24
A force in the x1° x2 direction, which is the width direction of the transfer board 20, does not act on the transfer board 20.

As shown in FIG.
If it is biased (as shown by the solid line in Figure 2), electrode 2
The lines of electric force between the outer part of the electrode 22 and the peripheral edge of the wafer 24 are as shown by 27c, and the lines of electric force between the outer part of the electrode 22 and the peripheral edge of the wafer 24 are as shown by 27d. become.

The electric force lines 27c and 27d are asymmetrical, and as will be described later, the electric force Fx acts on the wafer 24 in the X2 direction, and the wafer 24 is moved in the direction of the center line CL of the transfer substrate 20.

Further, as shown in FIG. 5, the wafer 24 is
When it is biased (indicated by the two-dot chain line in Fig. 2),
The lines of electric force between the outer part of the electrode 21 and the periphery of the wafer 24 are as shown by 27e, and the lines of electric force between the outer part of the electrode 22 and the periphery of the wafer 24 are as shown by 24f. become.

The electric force lines 27e and 27f are asymmetrical, and as will be described later, the electric force Fx acts on the wafer 24 in the X1 direction, and the wafer 24 is moved in the direction of the center line CL of the transfer substrate 20.

As a result, the wafer 24 is moved along the center line CL of the transfer substrate 20.
When it is biased toward the direction of the center line CL,
It is stably conveyed along the center line OL.

The wafer 24 is guided in the width direction of the transfer substrate 20 by electric force, no guide member is provided, and no dust is generated.

Next, the above electric force will be explained.

Due to the electric field between ff18i21.22 and the wafer 24, an electric force F directed toward the surface of the electrode 21.22 is applied to the wafer 24.
2 and an electric force F parallel to the plane of the electrodes 21.22. In particular, the electric force Fx is obtained by partially differentiating the energy of the electric field between the electrodes 21, 22 and the wafer 24 with respect to the deviation 1ix.

The electric forces Fx and F are respectively expressed by the following equations.

...■ ...■ εr=relative permittivity ε of the dielectric layer 218.22a. : Permittivity of vacuum do: Thickness of dielectric layers 21a and 22a d8: Thickness of air layer between the transport surface and wafer 24 V: Applied voltage Sl: Area of wafer facing electrode 21 S2: Wafer This is the area facing the electrode 22.

ε = 10. d8=2.0m, d,=0.0
6 tars.

When V=5 kV and a wafer 24 with a diameter of 150 m is transported, the electric force Fx has the following value.

Offset dimension X=0ats sharpening Fx=Oor10m
1.1gr 20#I#I 2.2gr30# 3.0gr 40#111 3.6gr50m 3.8gr At this point, it becomes difficult.

As can be seen from the figure, as the deviation dimension increases, Fx increases,
As the deflection dimension decreases, Fx also decreases. Also, the wafer 24 is about 3
0g'', and this force Fx is sufficient to move the floating wafer 24 in the direction of the center line CL.

As a result, the more the wafer 24 deviates from the center line CL, the stronger the force acting on the wafer 24 to return it to the center line CL. Center I! Transported along JCL.

Further, the electric force Fl causes the wafer 24 to be attracted to the upper surface of the transfer substrate 24 .

Here, the amount of air blown out from the hole 23 is determined by the amount of air blown out from the wafer 24 due to the electric force F.
7, and the wafer 24 is transported in a floating state.

In addition, the above electric force F2 is, as shown by the middle line ■ in Fig. 7,
It changes depending on the deviation dimension of the wafer 24 from the center line CL, but this change is small, and this change causes the wafer 24 to
The wafer 24 is stably transported without being disturbed.

Further, in order to effectively obtain the electric force Fx, the electrode 21.
22 is such that even if the wafer 24 is deflected, the wafer 24 remains in contact with the electrode 21.
．． The width should not exceed wafer 22, that is, wafer 2
If the actual maximum deviation dimension from the center 1i1CL of the R1 wafer 24 is Xl1lax, then the radius of the electrode 21.4 is Xl1lax.
It is desirable that the width WG be 22, and tW>R+X max.

(Effects of the Invention) As described above and according to the present invention, the wafer floats above the top surface of the transfer substrate and is transferred without mechanical guides, so the wafer can be transferred without generating dust. , it is possible to improve cleanliness.

Moreover, the blown air is used only to levitate and transport the wafer, and does not have the function of guiding the wafer.
The shape of the air blowing hole may be a simple shape that is inclined in the direction of conveyance of the evaporator, and machining is simple and manufacturing is easy.

[Brief explanation of the drawing]

FIG. 1 shows a second wafer transfer device according to an embodiment of the present invention.
FIG. 2 is a plan view of the wafer transfer apparatus of the present invention, FIG. 3 is a cross-sectional view taken along the line ■-■ in FIG. 2, and FIG. Figure 5 shows the state when the wafer is located at the center of the transfer substrate. Figure 5 shows the state when the wafer is displaced in the x2 direction. Figure 6 shows the relationship between wafer displacement dimension and horizontal electric force. FIG. 7 is a diagram showing the relationship between the wafer deflection dimension and the vertical electric force. FIGS. 8 (A), (B), and (C) are diagrams showing an example of a conventional wafer transfer device. FIGS. 9A, 9B, and 9C are diagrams showing another example of a conventional wafer transfer device. In the figure, 20 is a transfer substrate, 21.22 is an electrode, 21a and 22a are dielectric layers, 23 is an air outlet, 24 is a wafer, 25 is an air flow, 26 is a DC power supply, 27.27a to 27Nk electric force lines to beat. Patent Applicant: Fujitsu Ltd. 1- in Figure 2 shows a wafer transfer device according to an embodiment of the present invention.
A cross-sectional view taken along line 1. A diagram showing the state when the wafer is located at the center. Plan view Fig. 2 shows the relationship between wafer deviation dimension (+m) and horizontal electric force. Fig. 6 shows the relationship between wafer deviation dimension and vertical electric force. Figure 7

Claims (1)

[Claims] The wafer (
24) is floated above the transfer substrate (20) to transfer the wafer, in which a dielectric layer (21a,
22a) are laid side by side in the longitudinal direction on the carrier substrate (20) symmetrically with respect to the center line (CL) of the carrier substrate (20), and When a DC voltage is applied between the electrodes and the wafer deviates in the width direction (X_1, X_2) of the transfer substrate with respect to the center line (CL) of the transfer substrate, the center line (CL) A wafer transfer device characterized in that it is configured to apply an electric force (F_x) in the direction of .