An apparatus for providing a short return current path for RF current
between a process chamber wall and a substrate support is provided. The
RF grounding apparatus, which is RF grounded and is place above the
substrate transfer port, establishes electrical contact with the
substrate support only during substrate processing, such as deposition,
to provide return current path for the RF current. One embodiment of the
RF grounding apparatus comprises one or more low impedance flexible
curtains, which are electrically connected to the grounded chamber wall,
and to one or more low impedance blocks, which make contacts with the
substrate support during substrate processing. Another embodiment of the
RF grounding apparatus comprises a plurality of low impedance flexible
straps, which are electrically connected to the grounded chamber wall,
and to one or more low impedance blocks, which make contacts with the
substrate support during substrate processing. Yet another embodiment of
the RF grounding apparatus comprises a plurality of probes, which either
are electrically connected to the grounded chamber wall or are grounded
by other means, and actuators accompanying the probes. The actuators move
the probes to make electrical contact with the substrate support during
substrate processing.