JPS5928745Y2 - Rotating vacuum chuck device - Google Patents

Description

[Detailed Description of the Invention] Technical Field of the Invention The present invention relates to an improvement in a rotary vacuum chuck device that adsorbs a plate-like member using reduced pressure and rotates it at high speed.

TECHNICAL BACKGROUND OF THE INVENTION Conventionally, it has been widely practiced to adsorb plate-shaped members under reduced pressure and rotate them to perform various processing.

The equipment will be briefly explained using the surface treatment of semiconductor wafers as an example.
A rotating shaft having a suction surface on one end surface is rotatably supported by a bearing body provided on a base, and the rotary shaft is rotated to process the wafer while the wafer is suctioned and held on the suction surface by reduced pressure. ing.

The communication portion of the decompression path between the rotating shaft and the base body is kept airtight by labyrinth shaft seals provided on both sides thereof.

Problems with the Background Art Since the above-mentioned device is generally used at high speed rotation, for example around 5000 rpm, it is natural that the shaft seal preferably has a non-contact configuration.

However, recently there has been a demand for higher accuracy and higher efficiency in machining, so there is a demand for increasing the rotational speed of the rotating shaft.

For this reason, a plate-shaped wafer, which is a workpiece, is subjected to a stronger centrifugal force than in the past, so a larger suction force is required.

However, as mentioned above, since a non-contact shaft seal is used, the airtightness is poor, and the suction force that can withstand even stronger centrifugal force cannot be obtained, which is a major obstacle to improving accuracy and production efficiency.

As a countermeasure to this, attempts have been made to further reduce the gap between the shaft and the through hole, but this requires high-precision machining, making it very expensive, and also causing problems such as the adhesion of minute dust and deformation of the rotating shaft. Therefore, there was a problem that damage easily occurred and the operating rate decreased.

Purpose of the invention The object of the invention is to provide a rotary vacuum chuck device that improves the airtightness of the labyrinth shaft seal without increasing the accuracy, thereby improving machining accuracy and productivity.

Summary of the invention The present invention is constructed by providing a second pressure reducing path between a pair of bearing bodies provided on a base and both sides of a base side pressure reducing path as a first pressure reducing path provided on the base, By absorbing the leaked air flowing into the first pressure reducing path through the bearing bodies on both sides in the second pressure reducing path, a decrease in the degree of vacuum in the first pressure reducing path is prevented and the holding power of the vacuum chuck is improved. This rotary vacuum chuck is characterized by preventing the adhesion of such substances.

Embodiment of the Invention This embodiment is a rotary vacuum chuck for surface treatment of semiconductor wafers, similar to the conventional example, and will be described with reference to FIG.

A through hole 2 is provided in the base body 1, and bearing bodies 3, 3 made of ball bearings are attached to both ends of the through hole 2.

A rotating shaft 5 is rotatably supported by these bearing bodies 3, 3.

The rotating shaft 5 has one end face formed with a large diameter, a recess 6 in the center, and a flat surface 7 around the periphery forming a suction surface 9 on which the wafer 8 is attracted. There is.

The other end is connected to a drive body 11 via a shaft coupling 10, and is rotationally driven by this.

Furthermore, a labyrinth shaft sealing body 12 is provided in the intermediate portion.

This consists of five annular grooves 13. ... and an annular band 14 formed between them. . . . By maintaining an appropriate gap between the through hole 2 and the annular band 14, the leakage prevention effect is achieved without contact, and since it is similar to the generally known one, a detailed explanation will be omitted. .

Furthermore, this rotary shaft 5 is provided with a shaft-side pressure reducing passage 16 whose one end opens into the recess 6 and the other end opens into the annular groove 13 in the center.

The base body 1 is provided with a base body side pressure reduction passage 17 whose one end faces the annular groove 13 in the center and whose other end communicates with a depressurization source (not shown).
The first decompression path 18 is constituted by the above.

Then, by operating the control valve 19, the pressure is appropriately reduced and suction power is obtained.

Furthermore, the base body 1 includes bearing bodies 3, 3 and a base side pressure reducing passage 17.
Outer pressure reducing passages 20, 20 facing the outermost annular groove 13, 13 are provided between the The degree of vacuum is appropriately adjusted by control valves 21.21.

These outer pressure reducers 20 and 20 constitute a second pressure reduction path 23.

Next, the operation will be described. The first pressure reduction path 18 is communicated with a vacuum source to reduce the pressure (vacuum), and the wafer 8 is brought into contact with the suction surface 9 and held by suction.

In this state, leakage air from the bearing bodies 3, 3 flows into the first pressure reducing path 18, and a sufficient degree of vacuum is not reached.

Next, when the control valves 21 and 21 are opened, most of the leaked air is
It flows into the pressure reduction path 20, and the degree of vacuum in the first pressure reduction path 18 becomes extremely high, and the suction force becomes strong.

When a suction force sufficient to withstand the centrifugal force of rotation is obtained (for example, by measuring the pressure in the first decompression path 18), the rotary shaft 5 is rotated by the driver 11 to carry out a predetermined process, such as cleaning the wafer surface or removing a photosensitive agent. After coating, developing, etc. are completed, the rotation is stopped, the first decompression path 18 is opened to the atmosphere, and the wafer 8 is removed to complete the work.

In this embodiment, the annular band 14 of the labyrinth shaft enclosure is
．． ... were provided on the rotating shaft 5 side, but they may be provided on the base body 1 side, and the number thereof may be increased or decreased as necessary.

An annular 14° . . . provided on the rotating shaft 5 side as in this embodiment has the advantage that machining is easy.

The non-contact shaft seal is not limited to the labyrinth shaft seal 12.

Furthermore, the number of second pressure reducing passages 23 may be increased as appropriate.

Effects of the invention As detailed above, in the present invention, the second pressure reduction path is provided on both sides of the first pressure reduction path, so the vacuum level of the first pressure reduction path is, for example, 150 aHg vacuum system connected to the base side pressure reduction path. In this case, in the conventional case (without the second pressure reducing path), the outlet pressure of the base side pressure reducing path was 24,071 mHg, but in the case of this example, a degree of vacuum of 16,071 aHg was obtained.

Since the degree of vacuum has been improved in this way, machining accuracy has improved, and the gap between the labyrinth shaft seals can be the same as before.
It is extremely useful because it is inexpensive, and there are no accidents caused by adhesion of dust, and it helps improve production efficiency.

[Brief explanation of the drawing]

The figure is a sectional front view of essential parts of an embodiment of the present invention. 1...Base body, 2...Through hole, 3...
... Bearing body (ball bearing), 5 ... Rotating shaft, 9 ... Adsorption surface, 11 ... Drive body, 12 ... Labyrinth shaft seal Body, 13...
・Annular groove, 16... Shaft side pressure reducing path, 17...
...Base side pressure reduction path, 18...First pressure reduction path, 20
...Second pressure reduction path.

Claims (1)

[Scope of utility model registration request] A base body having a through hole, a pair of bearing bodies provided in the base body coaxially with the through hole, a rotating shaft rotatably supported by these bearing bodies and having one end surface as a suction surface, and this rotating shaft. a labyrinth shaft sealing body provided between the bearing body and having a plurality of annular grooves formed on the outer peripheral surface of the rotating shaft or the inner peripheral surface of the through hole; A shaft-side pressure reduction path provided on the rotating shaft and having one end opened to the suction surface and the other end opened to the labyrinth shaft seal; and a shaft side pressure reduction path provided in the base body, one end communicating with the decompression source and the other end opening to the labyrinth shaft seal. a first pressure reduction path consisting of a base body side pressure reduction passage that opens and communicates with the shaft side pressure reduction passage via the labyrinth shaft seal; and a first pressure reduction passage provided between the base body side pressure reduction passage and the pair of bearing bodies, respectively; A rotary vacuum chuck device comprising: a second pressure reduction path having one end open to the labyrinth shaft seal and each other end communicating with the pressure reduction source.