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CROSS-REFERENCE TO RELATED APPLICATIONS
The present application incorporates by reference each of the following
applications which are related cases of a common assignee and contain
related subject matter:
Ser. No. 060,991, filed 06/12/87, pending, Vacuum Slice Carrier; which is a
continuing application of Ser. No. 790,918, filed 10/24/85 by Davis, Cecil
and Matthews, Robert; now abandoned;
Ser. No. 060,976, filed 06/12/87, pending, Advanced Vacuum Processor; which
is a continuing application of Ser. No. 790,708, filed 10/24/85 by Davis,
Cecil; Spencer, John; Wooldridge, Tim; and Carter, Duane; now abandoned;
U.S. Pat. No. 4,687,542, issued Aug. 18, 1987, entitled Vacuum Processing
System by Davis, Decil; Matthews, Robert; and Hildenbrand, Randall;
Ser. No. 790,707, filed 10/24/85, pending, entitled Apparatus for
Plasma-Assisted Etching by Davis, Cecil; Carter, Duane; and Jucha, Rhett;
Ser. No. 061,017, filed 06/12/87, pending, entitled Integrated Circuit
Processing System; which is a continuing application of Ser. No. 824,342,
filed 1/30/86 by Davis, Cecil; Bowling, Robert; and Matthews, Robert; and
Ser. No. 915,608, filed 10/06/86, pending, entitled Movable Particle Shield
by Bowling, Robert; Larrabee, Graydon; and Liu, Benjamin;
Ser. No. 074,448, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Davis, Cecil; Matthews, Robert; Loewenstein, Lee; Abernathy,
Joe; and Wooldridge, Timothy;
Ser. No. 075,016, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Davis, Cecil; Loewenstein, Lee; Matthews, Robert; and Jones,
John;
Ser. No. 073,943, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Loewenstein, Lee; Rose, Alan; Kennedy, Robert III; Huffman,
Craig; and Davis, Cecil;
Ser. No. 073,948, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Loewenstein, Lee;
Ser. No. 073,942, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Jucha, Rhett; and Davis, Cecil;
Ser. No. 074,419, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Davis, Cecil; and Matthews, Robert;
Ser. No. 074,377, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Davis, Cecil; Jucha, Rhett; Hildenbrand, Randall; Schultz,
Richard; Loewenstein, Lee; Matthews, Robert; Huffman, Craig; and Jones,
John;
Ser. No. 074,398, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Davis, Cecil; Loewenstein, Lee; Jucha, Rhett; Matthews, Robert;
Hildenbrand, Randall; Freeman, Dean; and Jones, John;
Ser. No. 074,456 filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Davis, Cecil; Jucha, Rhett; Luttmer, Joseph; York, Rudy;
Loewenstein, Lee; Matthews, Robert; and Hildenbrand, Randall;
Ser. No. 074,399, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Jucha, Rhett; and Davis, Cecil;
Ser. No. 074,450, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Jucha, Rhett; Davis, Cecil; and Jones, John;
Ser. No. 074,375, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Jucha, Rhett; Carter, D.; Davis, Cecil; and Crank, S.;
Ser. No. 074,411, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Jucha, Rhett; Davis, Cecil; Carter, D.; Crank, S.; and Jones,
John;
Ser. No. 074,390, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Jucha, Rhett; Davis, Cecil; and Crank, S.;
Ser. No. 074,114, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Davis, Cecil; Loewenstein, Lee; Freeman, Dean; and Burris,
James;
Ser. No. 074,373, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Freeman, Dean; Burris, James; Davis, Cecil; and Loewenstein,
Lee;
Ser. No. 074,391, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Freeman, Dean; Burris, James; Davis, Cecil; and Loewenstein,
Lee;
Ser. No. 074,415, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Freeman, Dean; Burris, James; Davis, Cecil; Loewenstein, Lee;
Ser. No. 074,451, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Luttmer, Joseph; Davis, Cecil; Smith, Patricia; York, Rudy;
Loewenstein, Lee; and Jucha, Rhett;
Ser. No. 073,945, filed 7/16/87, pending, entitled Processing Apparatus and
Method: by Luttmer, Joseph; Davis, Cecil; Smith, Patricia; and York, Rudy;
Ser. No. 073,936, filed 7/16/87, abandoned, entitled Processing Apparatus
and Method; by Luttmer, Joseph; Davis, Cecil; Smith, Patricia; and York,
Rudy;
Ser. No. 074,111, filed 7/16/87, pending, entitled Processing Apparatus and
Method: by Luttmer, Joseph; York, Rudy; Smith, Patricia; and Davis, Cecil;
Ser. No. 074,386, filed 7/16/87, abandoned, entitled Processing Apparatus
and Method; by York, Rudy; Luttmer, Joseph; Smith, Patricia; and Davis,
Cecil;
Ser. No. 074,407, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by York, Rudy; Luttmer, Joseph; Smith, Patricia; and Davis, Cecil;
Ser. No. 075,018, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Davis, Cecil; Abernathy, Joe; Matthews, Robert; Hildenbrand,
Randall; Simpson, Bruce; Bohlman, James; Loewenstein, Lee; and Jones,
John;
Ser. No. 074,112, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Davis, Cecil; Matthews, Robert; York, Rudy; Luttmer, Joseph;
Jakubik, Dwain; and Hunter, James;
Ser. No. 074,449, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Davis, Cecil; Smith, Greg; Matthews, Robert; Jones, John;
Smith, James; and Schultz, Richard;
Ser. No. 074,406, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Davis, Cecil; Freeman, Dean; Matthews, Robert; Tomlin, Joel;
Ser. No. 073,941, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Davis, Cecil; Loewenstein, Lee; Tipton, Charlotte; Smith,
Randee, Pohlmeier, R.; Jones, John; Bowling, Robert; and Russell, I;
Ser. No. 074,371, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Loewenstein, Lee; and Davis, Cecil;
Ser. No. 074,418, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Fisher, Wayne;
Ser. No. 073,934, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Fisher, Wayne; Bennett, Tommy; Davis, Cecil; and Matthews,
Robert;
Ser. No. 074,403, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Davis, Cecil; Matthews, Robert; and Fisher, Wayne;
Ser. No. 075,019, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Davis, Cecil; Freeman, Dean; Matthews, Robert; and Tomlin,
Joel;
Ser. No. 073,939, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Davis, Decil; Abernathy, Joe; Matthews, Robert; Hildenbrandt,
Randy; Simpson, Bruce; Bohlman, James; Loewenstein, Lee; and Jones, John;
Ser. No. 073,944, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Cecil, Davis and Jucha, Rhett;
Ser. No. 073,935, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Liu, Jiann; Davis, Cecil; and Loewenstein, Lee;
Ser. No. 074,129, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Loewenstein, Lee; Freeman, Dean; and Davis, Cecil;
Ser. No. 074,455, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Loewenstein, Lee; Freeman, Dean; and Davis, Cecil;
Ser. No. 074,453, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Loewenstein, Lee; Freeman, Dean; and Davis, Cecil;
Ser. No. 073,949, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Loewenstein, Lee; and Davis, Cecil;
Ser. No. 074,379, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Loewenstein, Lee; and Davis, Cecil;
Ser. No. 073,937, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Loewenstein, Lee; and Davis, Cecil;
Ser. No. 074,425, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Loewenstein, Lee; Davis, Cecil; and Jucha, Rhett;
Ser. No. 073,947, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Davis, Cecil; Loewenstein, Lee; and Jucha, Rhett;
Ser. No. 074,452, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Jucha, Rhett; Davis, Cecil; and Loewenstein, Lee;
Ser. No. 074,454, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Jucha, Rhett; Davis, Cecil; and Loewenstein, Lee;
Ser. No. 074,422, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Davis, Cecil; Matthews, Robert; Jucha, Rhett; and Loewenstein,
Lee;
Ser. No. 074,113, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Davis, Cecil; Matthews, Robert; Loewenstein, Lee; Jucha, Rhett;
Hildenbrand, Randy; and Jones, John;
Ser. No. 073,940, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Davis, Cecil; and Matthews, Robert;
Ser. No. 075,017, filed 7/17/87, pending, entitled Processing Apparatus and
Method; by Loewenstein, Lee;
Ser. No. 073,946, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Davis, Cecil; and Matthews, Robert; and
Ser. No. 073,938, filed 7/16/87, pending, entitled Processing Apparatus and
Method; by Davis, Cecil; and Matthews, Robert.
BACKGROUND AND SUMMARY OF THE INVENTION
The present invention relates to apparatus and methods for manufacturing
integrated circuits and other electronic devices.
One of the basic problems in integrated circuit manufacturing is defects
caused by the presence of particulates. For example, if photolithography
with 0.8 micron minimum geometry is being performed to pattern a conductor
layer, the presence of a 0.5 micron particle can narrow the patterned line
enough to cause a defect which will prevent the circuit from operating
(either immediately due to an open circuit, or eventually due to
electromigration). For another example, if a 100 .ANG. particle of silicon
adheres to the surface and is included in a 200 .ANG. nitride layer being
grown, the dielectric will have greater chances of breaking down at that
point, even assuming that no subsequent process step disturbs the silicon
particle.
This problem is becoming more and more troublesome because of two trends in
integrated circuit processing: First, as device dimensions become smaller
and smaller, the size of a "killing defect" becomes smaller, so that it is
necessary to avoid the presence of smaller and smaller particles. This
makes the job of making sure that a clean room is really clean
increasingly difficult. For example, a clean room which is Class 1 (i.e.
has an atmosphere with less than one particle per cubic foot) for
particles of one micron and larger may well be Class 1000 or worse if
particle sizes down to 100 .ANG.ngstroms are counted.
Second, there is an increased desire to use large size integrated circuits.
For example, integrated circuit sizes larger than 50,000 square mils are
much more commonly used now than they were five years ago. This means that
each fatal defect is likely to destroy a larger area of processed wafer
than was previously true. Another way to think of this is that not only
has the critical defect size decreased, but the critical defect density
has also decreased.
Thus, particulates are not only an extremely important source of loss in
integrated circuit manufacturing yields, but their importance will
increase very rapidly in the coming years. Thus, it is an object of the
present invention to provide generally applicable methods for fabricating
integrated circuits which reduce the sensitivity of the process to
particulate contamination.
One of the major sources of particulate contamination is humangenerated,
including both the particles which are released by human bodies and the
particles which are stirred up by equipment operators moving around inside
a semiconductor processing facility (front end). To reduce the potential
for particulate contamination from this major source, the general trend in
the industry has been to make more use of automatic transfer operations.
Using such operations, for example, a cassette of wafers can be placed
into a machine, and then the machine automatically transfers the wafers,
one by one, from the cassette through the machine (to effect the
processing steps necessary) and back to the cassette, without manual
assistance.
However, efforts in the area of automatic transfer operations have served
to highlight the importance of a second source of particles, namely
particles generated by the wafers and the transfer mechanisms during
handling and transport operations. When the surface of the wafer jostles
slightly against any other hard surface, some particulate (of silicon,
silicon dioxide, or other materials) is likely to be released. The
particulate density inside a conventional wafer carrier is typically quite
high, due to this source of particulate. Moreover, many of the prior art
mechanisms for wafer transport generate substantial quantities of
particulate. The general problem is discussed in U.S. Pat. Nos. 4,439,243
and 4,439,244, which are incorporated by reference hereinto.
Some types of wafer processing are shown in U.S. Pat. Nos. 4,293,249 by
Whelan issued on Oct. 6, 1981, 4,306,292 by Head issued on Dec. 15, 1981,
and 3,765,763 by Nygaard issued on Oct. 16, 1973, which are incorporated
by reference hereinto.
The prior applications of common assignee discussed above addressed this
facet of the problem by providing a vacuum wafer carrier in which
particulate generation due to abrasion of the surface of the wafer during
transport is reduced. The teachings of these prior applications enabled
not only reduced generation of particulate in the carrier during transport
and storage, but also reduced transport of particulate to the wafer's
active face during transport and storage, by carrying the wafers face down
under a high vacuum. This allowed the rapid settling of both ambient and
transport generated particulate on other than the active wafer face.
The wafers can therefore be transported, loaded, unloaded and processed
without ever seeing atmospheric or even low vacuum conditions. This is
extremely useful, because, at pressures of less than about 10.sup.-5 Torr,
there will not be enough Brownian motion to support particles of sizes
larger than about 100 .ANG., and these particles will fall out of this
low-pressure atmosphere relatively rapidly.
FIG. 2 shows the time required for particles of different sizes to fall one
meter under atmospheric pressure. Note that, at a pressure of 10.sup.-5
Torr or less, even 100 .ANG. particles will fall one meter per second, and
larger particles will fall faster. (Large particles will simply fall
ballistically, at the acceleration of gravity.) Thus, an atmosphere with a
pressure below 10.sup.-5 Torr means that particles one hundred angstroms
or larger can only be transported ballistically, and are not likely to be
transported onto the critical wafer surface by random air currents or
Brownian drift.
The relevance of this curve to the various embodiments described in the
present application is that the prior applications were the first known
teachings of a way to process wafers so that the wafers are never exposed
to airborne particulates, from the time they are loaded into the first
vacuum process station (which might well be a scrubbing and pumpdown
station) until the time when processing has been completed, except where
the processing step itself requires higher pressures (e.g. for
conventional photolithography stations or for wet processing steps). This
means that the total possibilities for particulate collection on the
wafers are vastly reduced.
The prior applications cited above also taught use of the vacuum wafer
carrier design together with a load lock and vacuum wafer transport
mechanism at more than one process module, to provide a complete
low-particulate wafer transfer system. These vacuum load locks can
usefully incorporated mechanisms for opening a vacuum wafer carrier after
the load lock has been pumped down, for removing wafers from the carrier
in whatever random-access order is desired, and for passing the wafers one
by one through a port into an adjacent processing chamber. Moreover, the
load lock mechanism can close and reseal the vacuum wafer carrier, so that
the load lock itself can be brought up to atmospheric pressure and the
vacuum wafer carrier removed, without ever breaking the vacuum in the
vacuum wafer carrier. This process takes maximum advantage of the settling
phenomena illustrated in FIG. 2 and described in more detail below. The
wafer can then be moved in a virtually particulate free environment from
the carrier to the load lock, into the process chamber and back through
the load lock to the carrier for, potentially, an entire manufacturing
sequence.
A process station (which may optionally contain one process module or more
than one process module) has more than one load lock attached to it. This
has several actual and potential advantages. First, processing can
continue on wafers transferred in from one load lock while the other load
lock is being reloaded, so that throughput is increased. Second, with some
types of mechanical malfunction it will be possible to move at least the
in-process wafers out of the central module area (into one of the load
locks, or even into one of the process modules) to keep them from exposure
to ambient if it is necessary to vent the process module to correct the
malfunction. This means that even fairly severe faults may be recoverable.
Third, if separate transfer arms are provided inside each of the load
locks, this provides the further advantage that, if a mechanical problem
occurs with one transfer apparatus inside its load lock, the process
station can continue in production, using transfer through the other load
lock, while maintenance is summoned to correct the mechanical malfunction.
The various process modules disclosed in the present application provide a
tremendous improvement in the modularity of processing equipment. That is,
a reactor can be changed to any one of a very wide variety of functions by
a relatively simple replacement. It may be seen from the detailed
descriptions below that most of the different functions available can be
installed merely by making replacements in the wafer susceptor and related
structures--i.e. in the top piece of the reactor, which bolts on--or in
the feed structures, i.e. the structures directly below the wafer. Thus,
the basic configuration of the vacuum chamber and wafer transfer interface
is changed very little.
This capability confers tremendous advantages. First, the marginal capital
cost of adding a new processing capability is greatly decreased. Second,
the flexibility of manufacturing space is greatly increased, since
machines can be reconfigured with relative ease to perform new functions.
Third, the design development time for reactor structures is greatly
decreased. Fourth, the time required to train personnel in use of a new
reactor is also greatly decreased, since many key functions will be
performed identically across a wide variety of reactors. Fifth, the cost
of mistakes will be reduced, since operators will less frequently make
mistakes due to unfamiliarity or confusion due to variety of equipment.
Sixth, the carrying cost of an adequate spare parts inventory will be
reduced. Seventh, the delay cost of repair and maintenance functions can
be reduced, since many such functions can be performed off-line after an
appropriate replacement module is swapped into the production reactor.
Eighth, the presence of disused and obsolete machines in manufacturing
space can be minimized, because a machine which had been configured to
perform an unneeded function can be reconfigured.
The various classes of modules disclosed herein provide the advantage that
the "footprint" required to emplace them is minimal. That is, if one or
more process modules like those described is located in a clean room, only
a minimum of clean room floor space (which is very expensive) will be
required.
The capability for transferring wafers from one process chamber to another
without breaking vacuum is enhanced by the modular compatibility of the
below described embodiments. In particular, one of the advantages of
modular processing units of the kind disclosed herein is that a single
process station may advantageously contain several process modules like
those described, so that wafers need not even go through the load lock to
be transferred between two modules which are in a common station.
One way to think about the advantages of the various module designs
discussed below might be to consider that they provide a super-capable
reactor, i.e. has more adaptation capability than can ever be used for any
single process. Viewed in this light, it may also be seen that their
features are advantageous in sequential processing. That is, it has been
recognized as desirable to perform more than one process in the same
chamber without removing the wafer. The reactor designs disclosed herein
are particularly advantageous in doing this, since the "excess" capability
of the reactor design means that it is easier to configure it to perform
two sequential steps.
Other and further advantages are set forth within and toward the end of the
Description of the Preferred Embodiment.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be described with reference to the accompanying
drawings, wherein;
FIG. 1 shows a sample embodiment of a load lock which is compatible with
vacuum processing and transport of semiconductor integrated circuit
wafers.
FIG. 2 shows a graph of the time required to fall through air at various
pressures for particulates of various sizes.
FIG. 3 shows a sample wafer transfer structure, in a process station,
wherein the wafer is placed onto three pins by the transfer arm 28
reaching through the inter-chamber transfer port 30 from the adjacent
vacuum load lock chamber 12.
FIG. 4 shows a closer view of a sample embodiment of a multi-wafer vacuum
wafer carrier 10, docked onto the position registration platform 18 inside
a load lock like that of FIG. 1.
FIG. 5A and 5B show a plan view of a sample process stations including
process modules and wafer transfer stages, and a load locks.
FIG. 6 shows a configuration for a process module, which can be used as one
of the process modules inside the process station shown in FIGS. 5A and
5B.
FIG. 7 shows the plasma reactor of FIG. 6 in the closed position, as it
would be during the actual etch process.
FIG. 8 shows a plan view of the reactor of FIG. 6.
FIG. 9 shows an improved version of the process module of FIG. 6, in a
sample embodiment which includes the capability for process enhancement by
ultraviolet light generated in situ and also the capability is also
provided for providing activated species (generated by gas flows through
an additional plasma discharge which is remote from the wafer face) to the
wafer face. The module is shown in a process station which includes only
one module and one load lock, but can also be used in embodiments like
that of FIGS. 5A and 5B.
FIG. 10 shows a physical configuration for a process station which can be
used for implementing some of the embodiments described herein.
FIG. 11 shows a flow chart for a load lock control system which provides
particulate protection in a vacuum process system.
FIG. 12 is a detailed view of the structure to realize the capability for
process enhancement by ultraviolet light generated in situ, in embodiments
such as that of FIG. 9.
FIG. 13 shows an alternative version of the structure of FIG. 12, without
the isolator window which (in the embodiment of FIG. 12) helps separate
the gas flows of the ultraviolet source plasma from the process gas flows
near the wafer face.
FIG. 14 shows a further alternative version of the structure of FIG. 12,
wherein the plasma which provides the ultraviolet source is generated
between electrodes which are approximately cylindrical, and wherein
capability is also provided for providing activated species (generated by
gas flows through an additional plasma discharge which is remote from the
wafer face) to the wafer face.
FIG. 15 shows an example of a structure which generates activated species
by gas flows through a plasma discharge which is remote from the wafer
face, in embodiments like that of FIG. 14.
FIG. 16 shows an example of a module which provides the combined
capabilities of plasma bombardment from a plasma in close proximity to the
wafer face, and provision of activated species from a remote discharge,
and illumination of the wafer face with intense ultraviolet light.
FIG. 17 shows an example of a process module which provides two separate
gas feed distributors, and which is particularly advantageous for chemical
vapor deposition operations using two source species.
FIG. 18 shows a portion of a process module which permits rapid thermal
processing to be performed with reduced risk of wafer damage, and FIGS.
19A, 19B and 19C schematically show how the operation of the heat source
of FIG. 18 can alter the distribution of heating across the wafer, and
FIG. 20 shows sample plots of heating across a wafer diameter under the
conditions of FIG. 19B and 19C.
FIGS. 21A and 21B show two structures for reducing conductive heat transfer
between a wafer and a transparent vacuum window in rapid thermal
processing embodiments, including sample gas flow connections to supply a
purge gas to the void between the wafer and the transparent vacuum wall,
and FIG. 21C shows a third way to minimize this conductive heat transfer,
and FIG. 21D shows a sample vacuum seal which may be used with a
transparent vacuum wall which is subject to wide temperature variations in
a rapid thermal processing environment.
FIG. 22 shows another configuration of a heat source for rapid thermal
processing, in which the overall width of the heat source is minimal.
FIG. 23 shows the details of a process module, which provides combined
capabilities for high-temperature processing (and cleanup), plasma
bombardment, and provision of remotely generated activated species to the
wafer face.
FIG. 24 shows a process module, which provides combined capabilities for
high-temperature processing (and cleanup), plasma bombardment, provision
of remotely generated activated species to the wafer face, and
illumination of the wafer face by intense ultraviolet light generated in
situ.
FIG. 25A and 25B show a process module with capability for
edge-preferential processing (and specifically for photoresist bake and/or
edge bead removal).
FIG. 26A shows a process module which permits cleanup and sputter
deposition, and FIG. 26B and 26C show details of the module of FIG. 26A,
including a system for wafer transport within the module.
FIG. 27 shows a process module, compatible with a vacuum processing system,
wherein multiple wafers are simultaneously processed under high pressure
(or optionally under low pressure).
FIG. 28 shows a sample embodiment of an ion implanter process module which
is compatible with a vacuum processing system.
FIGS. 29A through 29G are magnified sectional views of the inner walls of
process gas piping, in several sample embodiments which provide advantages
in a semiconductor process modules.
FIGS. 30A through 30E show a distributor structure, and show the improved
results achieved with this structure in a descum process.
FIG. 31 is a block diagram of a computer control system.
FIG. 32 shows a process module with remote and in situ plasma.
FIGS. 33 and 34 show load lock chamber adapted to transfer wafers between a
vacuum carrier and ambient.
FIGS. 35 and 36, which are similar, respectively to FIGS. 33 and 34, a load
lock chamber adapted to transfer wafers between a vacuum carrier and a
transfer mechanism to a vacuum processing system.
FIGS. 37 through 40 show details of a vacuum processor which has two rings
of lamps.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention provides major new concepts in semiconductor process
methods and apparatus. The presently preferred embodiments will now be
discussed in great detail, but it must be appreciated that the concepts
which are included in these embodiments could also be used in many other
embodiments, and the scope of the invention is not delimited by the
particular examples shown.
FIG. 1 shows a sample embodiment of a vacuum wafer carrier 10 inside a
vacuum load lock chamber 12. The vacuum wafer carrier 10 is also shown, in
slightly greater detail, in FIG. 4.
The vacuum wafer carrier 10 is shown with its door 14 open. The door 14 is
mounted in a pivotal manner to one side (the left side as shown in FIGS. 1
and 4) of the main body of carrier 10 by, for example, hinges (not shown).
The door 14 has a vacuum seal 13 (FIG. 4) where it mates with the body of
the vacuum wafer carrier, so that the interior of vacuum wafer carrier 10
can be maintained for several days and possibly for several tens of days,
without enough leakage to raise the internal pressure above 10.sup.-3
Torr, for example, while the exterior of carrier 10 is subjected to the
atmosphere.
The vacuum wafer carrier 10 is adapted to dock with a position registration
platform 18. The position registration platform 18 is only partially
visible in FIG. 1, but is shown in more detail in FIG. 4. When a vacuum
wafer carrier 10 is placed inside the vacuum load lock chamber 12, the
position of the vacuum wafer carrier 10 will, therefore, be accurately
known. The vacuum wafer carrier 10 has ears 16 which engage vertical slots
17 fixed to the position registration platform 18. The vacuum wafer
carrier 10 can be slid into these slots until it rests on the position
registration platform 18, and thereby assure that the position of the
vacuum wafer carrier 10 is definitely known. It is also useful for the
position registration platform 18 to include two tapered pins 21. As shown
in FIG. 4, the pins 21 are both conical shaped but they can be of
different shapes, for example, one conical and one wedge-shaped. The pins
21 are positioned to engage tapered holes 23 in the underside of the
vacuum wafer carrier 10 when it is lowered with ears 16 engaged with slots
17. A wide variety of other arrangements could be used to assure
mechanical registration. Thus, the use of slots 17, ears 16, and pins 21
bring carrier 10 and chamber 12 into alignment (or mechanical
registration).
The vacuum wafer carrier 10 also has a safety catch 15 on it which secures
the door 14 from opening due to external forces being accidentally
applied. An ear 500 extends from the side of the door 14 away from the
hinges (not shown) which attach it to the main body of carrier 10. The
safety catch 15 can also be used to hold the door 14 closed if the carrier
10 is used as a non-vacuum carrier. The ear is adapted to engage with a
safety catch 15 rotatably mounted on the side (the right side as shown in
FIG. 4) of carrier 10. However, under normal conditions of transport, this
safety catch is not needed, since atmospheric pressure holds the door 14
shut against the internal vacuum of the vacuum wafer carrier 10. When the
vacuum wafer carrier 10 is placed inside the vacuum load lock chamber 12
by engaging ears 16 with slots 17, a fixed finger 19 will engage the
safety catch 15 and rotate it (upward as shown in FIG. 4) away from ear
500 to release it, so that the door 14 can be opened. Fixed finger 19
extends upward from platform 18 as shown in FIG. 4.
When the vacuum wafer carrier 10 is docked with the position registration
platform 18, the door 14 will also be engaged with the top of door opening
shaft 24. The door 14 can be provided with a shallow groove (not shown) in
its underside, which mates with a finger and arm 25 on the top of the door
opening shaft 24. The arm 25 is located to engage the door 14 near its
attachment to the main body of carrier 10 in order to rotate the door 14
as desired. Thus, after the load lock has been pumped down so that
differential pressure no longer holds the door 14 closed, the door can be
opened by rotating (clockwise as shown in FIG. 4) door opening shaft 24.
The door can be closed by rotating shaft 24 counterclockwise as shown in
FIG. 4.
After the vacuum wafer carrier 10 is placed in the vacuum load lock chamber
12 (FIG. 1) and closed the load lock lid 20, a purge (with dry nitrogen or
other clean gas), which can be at high pressure, is usefully applied
through the manifold 22 (FIG. 1) inside the load lock lid 20. The manifold
22 includes holes in lid 20, a connection with a source of the gas into
the holes in lid 20, and openings from the holes in the bottom of lid 20.
The gas flows from the source through the holes in lid 20 and exits
downward from lid 20 through the openings. The gas from the manifold 22
provides vertical flow which tends to transport particles downward. The
gas flow from the manifold 22 also helps to remove some of the large
particles which may have collected on the vacuum wafer carrier 10 during
its exposure to atmospheric conditions.
After this initial purge stage (i.e. for 30 seconds or more), the chamber
is then slowly pumped down to 10.sup.-3 Torr or less. This stage of the
pump down should be relatively slow, in order not to stir up random
particulates. That is, while low pressures do permit particles to fall
from the air, those particles will still be available on the bottom of the
chamber, and must not be stirred up if this can be avoided.
In order to make sure that the airborne particulates have actually fallen
out of the chamber air, the interior of the vacuum load lock can then be
allowed to stay at 10.sup.-3 or 10.sup.-4 Torr for a few seconds, to make
sure that all of the particles which are able to fall out of the air will
do so.
The use of the carrier 10 and chamber 12 in the manner described above
greatly reduce the problems of airborne particulates, which have always
been the dominant type of particulate transport, so that the problem of
ballistically transported particulates can now be usefully addressed.
A sloped bottom and polished sidewalls for the load lock may be used as a
modification of chamber 12. This would reduce the population of
particulates sticking to the sidewalls and bottom which can be sent
disturbed by mechanical vibration.
Note that vacuum gauges 62 (FIG. 1) are connected to the interior of the
vacuum load lock chamber 12. The vacuum gauges 62 include a high-pressure
gauge (such as a thermocouple), a low pressure gauge (such as an
ionization gauge), and a differential sensor which accurately senses when
the load lock interior pressure has been equalized with the atmosphere.
The door of a vacuum wafer carrier 10 is not opened until these gauges
indicate that desired vacuum has been achieved inside the load lock.
After a roughing pump and its isolation valve 702 (FIG. 31) has brought the
chamber down to a soft vacuum, the gate or isolation valve 39 can be
opened to connect the pump 38 to the interior of the load lock, and the
pump 38 can then be operated to bring the pressure down to 10 to the -3
Torr or less.
At this point, the pressures inside the vacuum wafer carrier 10 and the
vacuum load lock chamber 12 are more or less equalized, and the door 14
can be opened by activating by an do | | |
