Platen for semiconductor workpieces

Details Platen for semiconductor workpieces Platen for semiconductor workpieces

1998-09-14

2001-02-13

Leja, Ronald W. (Department: 2836)

Electricity: electrical systems and devices

Electric charge generating or conducting means

Use of forces of electric charge or field

Reexamination Certificate

active

06188563

ABSTRACT:

This invention relates to a platen for supporting a semiconductor workpiece for processing.
It is well-known to use platens for supporting semiconductor workpieces and, in recent years, many such supports have been configured as what are known as electrostatic chucks. These use an electrode or electrodes, which are generally separated from the support surface of the platen by a layer of dielectric, to create an electrostatic charge which serves to clamp the workpiece to the chuck.
In many semiconductor processing arrangements, it is desirable to supply radio frequency signals to the platen and this has previously been achieved using metallic platens.
From one aspect the invention consists in a platen for supporting a semiconductor workpiece for processing comprising, an insulating (for example ceramic) body having an upper workpiece support surface and a base; an RF electrode disposed in the body between the support surface and the base and extending generally parallel thereto and a ground plane electrode disposed in the body between the RF electrode and the base.
The existence of an RF electrode in the platen enables the construction of an RF driven platen, which can be totally integrated with an electrostatic chuck. Indeed, if the platen is an electrostatic chuck, then the electrostatic electrode may also constitute an RF electrode. Alternatively, if the body incorporates a heating element, then that element may additionally constitute the RF electrode.
In this latter arrangement the temperature sensor may be disposed in the body and additionally, or alternatively, the body may have voids or tubes extending therethrough to allow cooling of the body.
The provision of the ground plane enables the RF to be screened from the bottom of the platen, preventing an unwanted plasma from being created beneath the platen. This increases the efficiency of the RF drive and reduces the risk of workpiece contamination.
It may be advantageous to have at least a portion of the base open or absent to expose the ground plane. This would enable an electrical connection to be formed directly with the ground plane. If the connector is tubular other connections may pass through it without having to pass through the associated vacuum chamber.
Alternatively, an electrical contact in the ground plane may be disposed at the peripheral edge of the platen and may extend circumjacent thereto. In this case the body above ground plane may be less wide than the remainder to expose the portion of the ground plane and hence to allow the electrical contact to sit on the exposed portion.
A similar arrangement may be provided to form an electrical contact for the RF electrode. In that case the body above the RF electrode would be less wide than the remainder to expose a portion of the RF electrode and hence to allow the electrical contact to sit on the exposed portion.
The body may further define or contain an inlet for process gas which debouches at the peripheral edge of the body.
Although the invention has been defined above, it is to be understood that it includes any of the features set out above or in the following description.


REFERENCES:
patent: 5103367 (1992-04-01), Horwitz et al.
patent: 5151845 (1992-09-01), Watanabe et al.
patent: 5325261 (1994-06-01), Horwitz
patent: 5708557 (1998-01-01), Feigenbaum et al.
patent: 5886863 (1999-03-01), Nagasaki et al.
patent: 0 692 814 A1 (1996-08-01), None
patent: 0725 427 A2 (1996-08-01), None
patent: WO 88/09054 A1 (1998-11-01), None
IBM-TDB Oct. 1989, Double-sided electrostatic chuck, Oct. 1989.

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