Wafer machining apparatus

Details Wafer machining apparatus Wafer machining apparatus

1999-10-18

2001-10-02

Morgan, Eileen P. (Department: 3723)

Abrading

Machine

Rotary tool

C451S285000, C451S287000, C451S289000

Reexamination Certificate

active

06296555

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a wafer machining apparatus, and more particularly to a wafer machining apparatus for machining a semiconductor wafer in a chemical mechanical polishing (CMP).
2. Description of Related Art
A conventional semiconductor wafer machining apparatus is comprised mainly of a polishing part having a turntable, and a load stage. This wafer machining apparatus holds a wafer, which has not yet been machined, in a concave part of the load stage to hereby hold the centered (positioned) wafer. The load stage centers the wafer, so that the wafer can be transferred to the polishing part with the position being a reference and can be polished at a regular position. It is therefore important to center the wafer at the load stage in order to uniformly polish the surface of the wafer.
When the wafer is centered at the load stage, the load stage or a wafer holding part of the polishing part is moved so that they can become closer relatively to one another. The wafer holding part holds the wafer, held on the, load stage, by suction. After the wafer holding part is moved to the turntable, the wafer is polished in the state of being pressed by the wafer holding part against the turntable. That completes the polishing of one wafer.
In the conventional wafer machining apparatus, the wafer holding part holds the wafer, held (contained) in the concave part of the load stage, by suction. Thus, the wafer holding part cannot hold the wafer by suction because the wafer holding part comes into contact with the top of the concave part before holding the wafer by suction.
To solve this problem, the depth of the concave part is smaller than the thickness of the wafer, and the top of the wafer is projected from the top of the concave part. In this case, however, the wafer may be displaced from the concave part.
Therefore, it is preferable to form the concave part with a larger depth than the thickness of the wafer in order to hold the centered wafer. On the other hand, it is preferable to form the concave part with a smaller depth than the thickness of the wafer in order to hold the wafer with a chuck. Thus, there is a conflict between the two ideas.
SUMMARY OF THE INVENTION
In view of the foregoing, it is an object of the present invention to provide a wafer machining apparatus, which is provided with a load stage that is able to easily make a positioned wafer be held by a wafer holding part.
To achieve the above-mentioned object, the present invention is directed to a wafer machining apparatus which comprises a polishing part for polishing a wafer, and a load stage arranged adjacent to said polishing part and having a concave part for holding a wafer which has not been polished while positioning the unpolished wafer, said load stage transferring the wafer from said concave part to a wafer holding part of said polishing part, said wafer machining apparatus wherein: said load stage has a floating means for floating the wafer in said concave part.
According to the present invention, the floating means of the load stage is driven to float the wafer, which is positioned in the concave part, so that the wafer holding part can hold the wafer. Therefore, the wafer holding part can easily hold the positioned wafer.
According to the present invention, the floating means floats the wafer by supplying a liquid to the concave part, so that the wafer can be floated by the liquid. This is more stable than the floating by air.
According to the present invention, the floating means floats the wafer by supplying a mixture of a liquid and a gas to the concave part, so that the wafer can be floated by the mixture. This is more stable than the floating by air. Moreover, the wafer can easily be transferred to the wafer holding part.
According to the present invention, the load stage has cleaning liquid supply means for supplying a cleaning liquid to the top of the wafer floated by the floating means. The cleaning liquid washes away the dust, which is adhered to the top of the wafer, or the dust, which is likely to adhere to the wafer. Therefore, the wafer holding part can hold the clean wafer.


REFERENCES:
patent: 5779520 (1998-07-01), Hayakawa
patent: 6050884 (2000-04-01), Togawa et al.
patent: 6086457 (2000-07-01), Perlov et al.
patent: 6113465 (2000-09-01), Kim et al.
patent: 6132289 (2000-10-01), Labunsky et al.
patent: 3-149816 (1991-06-01), None
patent: 4-57663 (1992-02-01), None

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