Note: Descriptions are shown in the official language in which they were submitted.
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TITLE
LINER FOR SEMICONDUCTOR ETCHING CHAMBER
FIELD OF THE INVENTION
The present invention relates to dome liners and chamber liners
for use in processes involving dry etching of semiconductor devices.
BACKGROUND OF THE INVENTION
Dry etching processes using chambers with dome-shaped
ceramic or aluminum tops and aluminum sides and bottoms, in part,
are used to manufacture semiconductor wafers. The dry etch process
uses plasma state gases to perform chemical and physical erosion on
unprotected surfaces of a semiconductor wafer surface. The mixture of
gases used, as well as other variables such as the electrical power and
pressure settings, will alter the aggressiveness and uniformity of
erosion of the semiconductor surface and the chamber. The chamber is
filled with gas and semiconductor wafers are placed inside the
chamber. Gas is then ionized with a plasma field to make the gas
reactive so as to etch wafers inside the chambers. A plasma field is
usually made of chemically active species of gaseous compounds such
as fluorine, oxygen and chlorine. The exact mixture of gaseous
compounds is chosen to balance the functions of the individual gases so
as to achieve a desired etch activity. Etching can result in the
generation of etching by-products that, if not removed, will eventually
contact and damage the wafers in the chamber. These byproducts can
also damage the interior sides and top of the etching chamber.
A thin-walled, seamless, polymer liner placed snugly inside the
chamber so as to cover the aluminum sides of the chamber was
reported to draw etching by-products away from the semiconductor
devices. Sakai, et al., Japan Application No. 10-150137, May 16, 1999.
Using a thin polymer liner to maintain uniform chamber surface
temperatures during etching processes, the Sakai patent application
reports the transfer of etched by-products away from semiconductor
wafers by the deposition of the by-products on the polymer liner
surfaces in the interior of the chamber. The polymer liner was
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WO 01/52303 CA 02393283 2002-05-31 PCT/[JSOl/0095~
reported to be thin, 2.0 mm or less in thickness, so that the
temperature within the chamber is accurately regulated by the cooling
means located outside of the chamber. As reported in the Sakai patent
application, a liner having a wall thickness greater than 2.0 mm would
insulate the contents of the chamber from the exterior cooling means
allowing chamber surface temperatures to increase during etching
processes. For this reason, higher surface temperatures would
decrease the deposition of by-products on the polymer liner surfaces.
The Sakai patent application reports a solution to the problem of
removing by-products away from semiconductor devices located in a
chamber, however, other problems associated with etching still exist.
Gas generated in the chamber can be highly toxic and could escape if
the chamber integrity is compromised. Consequently, a device capable
of protecting the walls and the top of chamber from the gas would be
desirable. The device should have a long service life and be able to
survive many hours of each individual operation because the removal
and replacement of a chamber component slows down the production
process and significantly increases manufacturing costs.
In view of the foregoing, a liner for a chamber interior for
etching semiconductor devices that has a long life and protects against
chamber corrosion has been developed.
SUMMARY OF THE INVENTION
In one aspect, the present invention relates to dome and
chamber liners that may be used during numerous dry etching
processes while protecting the inside walls and top of the chamber.
The liners of the present invention are prepared from high
performance resins having a wall thickness greater than 2.0 mm, and
preferably in the range of 3 mm to 8 mm. High performance resins are
characteristically stable at high temperatures (above 100°C), resistant
to wear, resistant to plasma and oxidative stress and dimensionally
stable, i.e., tending not to creep or deform. The service life of a liner
correlates directly with the thickness of a liner. Dome liners of the
present invention fit to an inside top of a chamber of a dry etching
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TITLE
LINER FOR SEMICONDU
WO 01/52303 CA 02393283 2002-05-31 PCT/US~l/00950
apparatus used in semiconductor manufacture and comprise high
performance resin.
In another aspect, the present invention relates to chamber
liners that fit to an inside wall of a chamber of a dry etching apparatus
used in semiconductor manufacture, said liners comprising a high
performance resin having a wall thickness of greater than 2.0 mm.
The present invention also relates to a chamber of a dry etching
apparatus comprising a dome liner of the present invention. The dome
liner fits to an inside top of the chamber. The chamber may also
include a chamber liner of the present invention.
As used herein, with respect to the present invention, the
following shall apply:
"dome liner" refers to a covering used to cover the top
interior portion of the chamber.
"chamber liner" refers to a covering used to cover the
interior chamber sidewalls.
A liner for the top interior portion of a dry etching chamber may
be prepared from a high performance resin. A liner for the interior
sidewalls of a dry etching chamber may be prepared from a high
performance resin and may have a wall thickness of greater than
2.0 mm.
DESCRIPTION OF THE FIGURES
Figure 1 illustrates a dome liner of the present invention.
Figure 2 illustrates a chamber liner of the present invention.
Figure 3 illustrates an overhead view of a variation of a dome
liner and the chamber liner in the present invention.
Figure 4 illustrates a side view of the dome liner and the
chamber liner pictured in Figure 3.
Figure 5 illustrates the joint between the dome liner and the
chamber liner pictured in Figure 4.
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DETAILED DESCRIPTION OF THE INVENTION
Dome and chamber liners of the present invention are prepared
from high performance polymer resins, preferably a high-performance
thermoplastic resin. Suitable resins include polybenzimidazole,
polyimide, polyetherimide, polyamideimide, polyaryletherketone,
polycarbonate, polyarylate, polyethersulfone, aromatic polyamide,
tetrafluoroethylene/perfluoroalkylvinyl ether copolymer (PFA),
polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE),
tetrafluoroethylene/hexafluoropropylene copolymer (FEP),
polyvinylidend fluoride (PVDF), polyvinylfluoride (PVF),
ethylene/tetrafluoroethylene copolymer (ETFE). It is preferred that
the high performance resin contain no halogen atoms.
The high performance resins used in this invention may be
readily processed by methods and processing equipment normally used
in industry to form high performance polymers. Typical methods for
forming dome liners and chamber liners include spray coating,
machining, injection molding, compression molding, plasma coating,
rotomolding, strip bending and welding. The forming conditions
required to produce satisfactory articles depends on several process
variables, such as mold complexity and dimensions, sheet thickness
and polymer variables such as melt viscosity and glass transition
temperature (Tg). These conditions can be determined by techniques
typically used by those skilled in the art.
As shown in Figure 1, a dome liner is preferably in the shape of
a dome that corresponds to the shape of the ceramic top of a chamber
used in a dry etch process. However, the dome liner may be molded
into any shape that corresponds to the top of a chamber used in a dry
etch process.
The chamber and dome liners of the present invention have a
wall thickness preferably greater than 2.0 mm, and most preferably in
the range of 3 mm to 8 mm. The service life of a dome liner correlates
directly with the thickness of the dome liner.
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WO 01/52303 PCT/USO1/00950
As shown in Figure 2, the chamber liner is preferably in the
shape of the chamber.
A typical chamber liner would be cylindrical and 34.5 cm outer
diameter and 10.2 cm high. On top of the chamber liner would be a
dome liner in the shape of a dome having an outer diameter of 34.5 cm
and a 10.2 cm deep. Preferably, the dome liner has less than 0.8 mm
clearance with the dome to prevent the generation of plasma between
the dome and the dome liner. Similarly, the chamber liner preferably
has less than 0.8 mm clearance with chamber to prevent formation of
plasma fields between the chamber and the liner. Also preferably, the
dome liner is not mechanically attached to the dome.
To use a dome liner, the dome liner is placed inside of the dome
so that the convex side of the dome liner is juxtaposed with the concave
inner part of the chamber. To use the chamber liner, the chamber
liner is placed inside of the chamber such that the annular surface of
the liner with the greatest radius is juxtaposed with the inner radial
surface of the chamber. Dome and chamber liners of the present
invention at 5 mm thickness may last at least 1000 RF (radio
frequency) hours in a conventional dry etching process. Dome liners
and chamber liners may be used separately or in conjunction with each
other.
The dome liner of Figure 3 has an opening at the top of the
dome. This open dome liner offers protection to domes in which the top
of the dome of the plasma generation chamber is not involved in
plasma generation and has no contact with harmful byproducts of the
plasma generation process.
The dome liner of Figure 4 shows a dome liner 1 resting on top of
the chamber liner 3. As show in Figure 5 and described in Dome Liner
2 and Chamber Liner 1 below, the dome liner may have a groove
system comprising a groove 5 on the dome liner that is complimentary
to a groove 7 on the chamber liner. This groove system would aid in
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fitting the dome liner 1 with the chamber liner 3 when the dome liner 1
rests on top of the chamber liner 3.
EXAMPLES
Dome Liner 1
1400 g of an amorphous, aromatic thermoplastic polyimide resin
having a Tg of 239°C were placed into a 43.2 cm x 43.2 cm plaque mold.
The top plate of the plaque mold was added and the mold was placed
into a preheated (296°C) platen press having a platen size of 61 cm x
61 cm. A thermocouple was inserted into the plaque mold and the
plague mold allowed to heat up without pressure to 288°C. At this
point 3.44 x 106 Pascal of pressure was applied. After 1 minute the
cooling cycle on the press was started and the plaque mold allowed to
cool to room temperature under pressure. Once cool, a compression
molded plaque or 5 mm thickness was removed from the mold.
The plaque was vacuum thermoformed using a standard
industrial thermoformer equipped with ceramic heaters and a remote
pyrometer to measure the surface temperature of the plaque while it is
in the oven. Using a vacuum of about 95 kPa, a mold temperature
between 246°C and 275°C and a sheet forming temperature between
250 and 275°C, the compression-molded plaque was formed into a
dome having an outer diameter of 34.5 cm and a 10.2 cm deep draw
and a minimum thickness of 2.5 mm. A top lip of the dome, formed
through the molding process, was removed to provide the final article.
The dome showed good mold surface replication. The dome was
subsequently trimmed using conventional milling machines into the
desired final part.
Dome Liner 2 and Chamber Liner 1
For this example, liner material was not provided at the very
apex of the dome since most significant erosion of the dome was
occurring at the periphery of the dome immediately under the RF coils
that induce the plasma. Two 50.8 mm high annular plates of
pyromellitic dianhydride 4,4'-diaminodiphenylether polyimide (as used
in DuPont Vesper SP-1 parts and shapes), having outer diameters of
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360 mm and inner diameters of 19G mm, were machined and
assembled together to line the lower 100 mm of the chamber dome.
The lower plate was machined into a cylinder or outer diameter
345 mm and a wall thickness of 3 mm. A mating groove was cut into
the top surface from the middle of the wall to the outer diameter.
An upper place covered all the critical areas of the curvature of
the dome. The outer surface was turned on a lathe to match the
surface shape of the particular dome. The thickness of the liner was
set at 5 mm when the inner surface was turned. An extra tab of
material was left on the lower surface around the outer diameter to
interlock with the lower plate. When the upper machined plate was
placed on the lower machined plate in the chamber, the upper
machined plate was held in place by gravity and the restraints of the
dome immediately above and around it.
Chamber Liner 2
A dome of the type in Dome Liner 1 was prepared. An
untrimmed part was then trimmed on both the top and the bottom
with a cutting tool to form a seamless ring 5.1 cm high, 3 mm
thickness and having an outer diameter of 345 cm. The chamber liner
was then machined to uniform thickness.
Chamber Liner 3
A plaque of the type in Dome Liner 1 was prepared. The plaque
had the dimensions 740mm x 740mm x 450mm. This plaque was
placed in a drying oven set at 200~C for 48 hours. The dry plaque was
vacuum thermoformed using a standard industrial thermoformer
equipped with ceramic heaters and a remote pyrometer to measure the
surface temperature of the plaque while in the oven. Using a vacuum
of about 95 kPa, a mold temperature between 215°C and 238°C and
a
sheet forming temperature 275°C, the compression-molded plaques
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were formed into domes having an outer diameter of 60.8 cm and a
12.7cm deep draw.
An open untrimmed end of the dome was then trimmed on both
the top and the bottom with a cutting tool to form a seamless ring 11.4
cm high having an outer diameter of 60.8 cm and a minimum wall
thickness of 4.85mm. The chamber liner was then machined to
uniform thickness.
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