Etch chamber

Details Etch chamber Etch chamber

2000-06-13

2001-08-07

Dang, Thi (Department: 1763)

Adhesive bonding and miscellaneous chemical manufacture

Differential fluid etching apparatus

With microwave gas energizing means

Reexamination Certificate

active

06270621

ABSTRACT:

This invention relates to an apparatus for processing semiconductor substrates. More particularly, this invention relates to an improved etch chamber for processing semiconductor substrates.
BACKGROUND OF THE INVENTION
Plasma etch chambers for processing semiconductor substrates are well known and can be exemplified by reference to the prior art chamber of FIG.
1
.
Referring to
FIG. 1
, a semiconductor substrate to be etched
20
is mounted on an RF powered cathode support pedestal
22
which is mounted in a vacuum chamber
10
. A showerhead gas distribution plate
26
allows etchant plasma precursor gas to enter the vacuum chamber from an external source
28
. The gas distribution plate
26
can also act as the anode which is electrically grounded. A source of coolant gas can also be supplied to the chamber through a passage
32
in the pedestal
22
. The coolant gas enters the space between the backside of the substrate
20
and the top of the support pedestal
34
and serves to couple the temperature regulated support pedestal
22
and the substrate
20
to ensure temperature regulation of the substrate
20
during processing. The support pedestal
22
can be heated or cooled during processing; however, generally the large thermal mass of the support pedestal
22
relative to the mass of the substrate
20
serves to dissipate heat generated in the substrate
20
during the plasma etching process, thereby controlling the substrate temperature during processing.
Surrounding the pedestal support
22
is a cylindrical support
36
which is larger in diameter than the pedestal support
22
, to allow independent vertical movement of the cylindrical support
36
.
In addition, a metal clamping ring
38
overlies the substrate
20
during processing. The clamping ring is supported on the cylindrical support
36
at all times. During processing, the cylindrical support
36
is lowered so that the clamping ring
38
contacts the substrate
20
.
Since the prior art etch chamber of
FIG. 1
is meant for continuous operation, particulates can build up in the chamber from various plasma and etch species. Since if these particulates deposit onto the surface of the substrate
20
they will reduce the yield of good devices from the substrate
20
, reduction of particles generated in the etch chamber and prompt removal of any particulates that do form during processing is mandatory.
Thus a continuous load lock purge has been used to maintain a positive pressure between an adjacent load lock chamber and the processing etch chamber, and to prevent particulates from contact with the substrate. This continuous load lock purge has been moderately successful in reducing the formation of particles and in the prompt removal of any particles that do form in the chamber.
The chamber
10
is designed for continuous usage and many hundreds of substrates are desirably processed consecutively before taking the chamber
10
apart for cleaning. Thus the chamber
10
becomes more contaminated and the number of particles therein increases over time. Since cleaning the chamber
10
is expensive, we sought to determine the causes of particle generation in the above chamber and to find ways of reducing the number of particles generated and collected in the chamber, both to reduce contamination of the substrates and to increase the time or number of processing cycles between cleanings.
SUMMARY OF THE INVENTION
The present invention provides several improvements to an etch chamber that reduces particle formation.
A cover for the clamping ring is made of an inert, rigid, ceramic material having grooves in its upper surface. The grooves in the clamping ring cover allow the collected or gettered particles to be removed from the etch chamber by the gas stream exiting the chamber into the chamber exhaust system.
Metal antennas can be inserted into openings in the ceramic cover. The metal antennas act as getters for particles in an area away from the substrate being processed.
The clamping ring of the invention is made from ceramic instead of metal, and, because ceramics are electrically neutral, ion bombardment of the clamping ring is avoided or reduced, which bombardment also produces particles in the chamber.
The clamping ring support cylinder on which the clamping ring is supported in the chamber, is provided with a plurality of openings or windows to allow particles generated during processing to be carried away from the substrate with a continuous load lock purge gas stream which exits the chamber through its exhaust system.
The resultant modified etch chamber of the invention contains fewer particles, even after many hundreds of substrates have been processed in the chamber.


REFERENCES:
patent: 3901499 (1975-08-01), Sporrer
patent: 4842683 (1989-06-01), Cheng et al.
patent: 4869801 (1989-09-01), Helms et al.
patent: 4944860 (1990-07-01), Bramhall, Jr. et al.
patent: 4956043 (1990-09-01), Kanetomo et al.
patent: 4978412 (1990-12-01), Aoki et al.
patent: 5009738 (1991-04-01), Gruenwald et al.
patent: 5078851 (1992-01-01), Nishihata et al.
patent: 5094885 (1992-03-01), Selbrede
patent: 5292399 (1994-03-01), Lee et al.
patent: 5298720 (1994-03-01), Cuomo et al.
patent: 5304248 (1994-04-01), Cheng et al.
patent: 5316278 (1994-05-01), Sherstinsky et al.
patent: 5343938 (1994-09-01), Schmidt

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