Plastic and nonmetallic article shaping or treating: processes – Utilizing heat releasable stress to reshape solid workpiece
Reexamination Certificate
1998-08-05
2002-07-02
Ortiz, Angela (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Utilizing heat releasable stress to reshape solid workpiece
C264S3420RE, C414S941000
Reexamination Certificate
active
06413459
ABSTRACT:
TECHNICAL FIELD
The present invention relates to methods for handling and processing microelectronic-device substrate assemblies, such as semiconductor wafers, field emission displays and other types of substrates with one or more microelectronic-devices. More particularly, the present invention relates to handling and processing substrate assemblies when the substrate assemblies are attached to a backing film stretched over a frame.
BACKGROUND OF THE INVENTION
Microelectronic-device substrate assemblies are typically semiconductor substrates used in the manufacturing of semiconductor devices, field emission displays and other microelectronic devices. In a typical application for manufacturing semiconductor devices, the substrate assemblies are semiconductor wafers upon which a plurality of individual devices are formed in several processing steps. Memory devices, for example, are fabricated on 6-12 inch wafers that provide enough surface area to fabricate several hundred individual memory devices on a single substrate assembly. After the circuits of the individual devices have been constructed, the substrate assembly is cut to separate the devices from one another, and then the individual devices are often packaged for mounting to a printed circuit board assembly.
One aspect of manufacturing or using substrate assemblies is handling the substrate assemblies in processing machines. Substrate assemblies are fairly delicate structures that may chip or crack, and the integrated circuits of the individual devices are very delicate structures that may be damaged or destroyed by static electricity. To protect the substrate assemblies during certain stages of processing, the substrate assemblies are attached to a backing film that is stretched over a metal frame to avoid directly contacting the substrate assemblies with the handling equipment. In a typical fabrication process, for example, substrate assemblies are coupled to frames by the backing film for processing in a dicing machine that cuts the substrate assemblies to separate the devices from one another. Additionally, because the backing film may stretch and cause difficulties in cutting the substrate assemblies in the dicing machines, the frames and the substrate assemblies are placed in an “expander” machine that shrinks the backing film until it is taut. Existing expander machines, however, have many drawbacks that make it difficult to handle substrate assemblies.
FIG. 1
is an isometric view partially illustrating an existing expander machine
10
that has a processing station
20
, a loader
30
and a cassette
50
. The processing station
20
has a plate assembly with a first plate
22
and a second plate
24
spaced apart from one another by a gap
26
. A number of posts
27
attached to the table
12
support the first and second plates
22
and
24
to position the plate gap
26
at a desired elevation with respect to the cassette
50
. The processing station
20
has a first side
28
facing the loader
30
and a second side
29
facing the cassette
50
.
The loader
30
is mounted to a base
31
proximate to the first side
28
of the processing station
20
. The loader
30
has a housing
32
, a motor
33
attached to the housing
32
, and a spring-loaded tape assembly
34
with a thin metal tape
36
that projects from the housing
32
. The tape
36
includes a plurality of holes
38
arranged in a line along the length of the tape
36
to receive the teeth of a sprocket
39
attached to an output shaft of the motor
33
. A clamp
40
is attached to the end of the tape
36
. The clamp
40
has a pair of clips
42
, and each clip
42
has an upper finger and a lower finger that are biased toward one another.
In operation, the motor
33
turns the sprocket
39
to move the tape
36
and the clamp
40
along a processing path P through the gap
26
between the first and second plates
22
and
24
. For example, to remove a selected substrate assembly from the cassette
50
, the motor
33
drives the tape
36
out of the tape assembly
34
until the clamp
40
engages a frame
52
to which the selected substrate assembly is attached via a backing film. The motor
33
then reverses the rotation of the sprocket
39
to pull the frame
52
and selected substrate assembly out of the wafer cassette
50
and into the plate gap
26
between the first and second plates
22
and
24
at the processing station
20
. The spring-loaded tape assembly
34
accordingly recoils a portion of the tape
36
in a manner similar to a tape measure. After the substrate assembly has been processed at the processing station
20
, the motor
33
rotates the sprocket
39
to drive the tape
36
from the tape assembly
34
until the frame
52
and selected substrate assembly are replaced in the wafer cassette
50
. The motor
33
then reverses the rotation of the sprocket
39
very quickly to disengage the clips
42
from the frame
52
and retract the clamp
40
to the loader
30
.
One drawback with the expander machine
10
is that the loader
30
may not accurately drive the tape
36
and the clamp
40
along the processing path P to accurately pick up, position and release the frames
52
for processing the substrate assemblies. More particularly, the thin metal tape
36
often cracks in a line between the holes
38
. The teeth of the sprocket
39
may accordingly pass through the cracks between the holes
38
in the thin metal tape instead of pushing against the portion of the tape
36
between the holes
38
. The cracks in the tape
36
between the holes
38
typically develop to a point at which the loader
30
is inoperable and the tape assembly
34
must be replaced. Repairing the loader
30
, however, results in down-time for the expander machine
10
. Thus, the durability of the tape assembly
34
is a significant drawback in handling microelectronic-device substrate assemblies in the expander machine
10
.
Another problem of the expander machine
10
is that the clamp
40
may hit one of the first and second plates
22
and
24
of the processing station
20
as the loader
30
drives the tape
36
from the loader
30
to the cassette
50
. This problem arises because the clamp
40
causes the thin tape
36
to bend downward as the clamp
40
moves from the loader
30
toward the processing station
20
. The vertical displacement of the clamp
40
accordingly increases with increasing distance from the loader
30
such that the height of the loader
30
is generally adjusted at the initial set-up so that the clamp
40
passes through the plate gap
26
on both the first and second sides
28
and
29
of the processing station
20
. Moreover, as the thin tape
36
wears and cracks develop between the holes
38
, the bend radius of the tape
36
changes over time causing the vertical displacement of the clamp
40
along the processing path to also change. The clamp
40
may even hit one of the first or second plates
22
or
24
when the tape
36
wears down after a period of use. When this occurs, the height of the loader
30
must be readjusted to compensate for the changes in the integrity of the tape
36
. Adjusting the height of the loader
30
so that the clamp
40
passes through the gap
26
of the processing station
20
is a difficult and time-consuming process because it is generally a trial-and-error procedure. Therefore, constantly adjusting and readjusting the loader
30
so that the clamp
40
can “shoot the gap” of the plate gap
26
also causes down-time for the expander machine
10
.
Still another drawback of the expander machine
10
is that the clamp
40
may not positively engage or disengage the frames
52
. The frames
52
wear down the interior surfaces of the clips
42
causing a gap to form between the fingers of each clip
42
. After the frames
52
wear down the interior surfaces of the clips
42
, the clamp
40
may not sufficiently engage a frame
52
to pull the frame
52
out of the cassette
50
. Therefore, the durability of the clamp
40
also presents another operating concern of using the expander m
Anderson Sheldon
Ibarra Tony
Ortiz Angela
Perkins Coie LLP
LandOfFree
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