Abrading – Machine – Combined
Reexamination Certificate
1999-08-05
2002-06-18
Rose, Robert A. (Department: 3723)
Abrading
Machine
Combined
C015S236100
Reexamination Certificate
active
06406358
ABSTRACT:
TECHNICAL FIELD
The present invention is directed toward methods and apparatuses for cleaning the surface of a microelectronic substrate.
BACKGROUND OF THE INVENTION
During processing of substrates and substrate assemblies used to form microelectronic devices, the surfaces of the substrates and substrate assemblies can become contaminated with particulate matter. The contaminants must generally be removed to prevent interference with subsequent processing steps and/or to prevent improper formation or operation of the microelectronic devices. Accordingly, several conventional tools can rinse the surfaces of the microelectronic substrates between processing steps to remove the contaminants.
FIG. 1
is a partially schematic, front isometric view of a conventional apparatus
10
(such as a model AS-2000, available from Dai Nippon Screen of Hikone, Japan) having a substrate support
20
that supports a substrate
12
having an upper surface
14
and a lower surface
16
facing opposite the upper surface
14
. The substrate support
20
can include a plurality of rollers
21
, each having an outer surface
22
engaged with an outer rim
18
of the substrate
12
. Each roller
21
is rotatable about a roller axis
23
, as indicated by arrow A. As the rollers
21
rotate about the roller axes
23
, they rotate the substrate
12
about a substrate rotation axis
13
, as indicated by arrow B.
The apparatus
10
can further include two brush assemblies
30
, one proximate to the upper surface
14
of the substrate
12
and the other proximate to the lower surface
16
. Each brush assembly
30
overhangs the outer rim
18
of the substrate
12
, and is intersected by the substrate rotation axis
13
. Accordingly, the entire area of the upper and lower surfaces
14
,
16
can contact the brush assemblies
30
as the substrate
12
rotates about the substrate rotation axis
13
.
Each brush assembly
30
can include a brush support
40
having a first flange
41
secured to a second flange
42
with screws
46
to clamp a brush
50
therebetween. The brush
50
includes a flat, cross-shaped base
53
having four contact portions
51
projecting toward the substrate
12
. Each contact portion
51
has a pair of edges
52
that bear against the substrate
12
. The brush support
40
has a central opening
44
and the base
53
of the brush
50
has a base opening
55
aligned with the central opening
44
.
Each brush support
40
is removably coupled to a chuck
80
which is in turn coupled to a drive mechanism
31
(shown schematically in
FIG. 1
) to rotate the brush support
40
about a brush rotation axis
33
, as indicated by arrow C. Each brush support
40
is also coupled to a fluid supply conduit
32
(shown chematically in
FIG. 1
) which is in turn coupled to a source of cleaning liquid (not shown), such as de-ionized water. The fluid supply conduit
32
directs liquid through the base opening
55
in the base
53
and the central opening
44
of the brush support
40
. The liquid passes through the central opening
44
directly to the surface of the substrate
12
. When the liquid reaches the surface of the substrate
12
, the rotational motion of the brushes
50
about the brush rotation axes
33
and the rotational motion of the substrate
12
about the substrate rotation axis
13
together distribute the liquid over the surfaces
14
,
16
of the substrate
12
. The liquid entrains contaminants on the substrate
12
, and the contact portions
51
of the brushes
50
sweep the liquid and the entrained contaminants from the substrate
12
.
One drawback with some conventional substrate cleaning devices of the type shown in
FIG. 1
is that the devices may not uniformly distribute the cleaning liquid over the surfaces
14
,
16
of the substrate
12
. As a result, residual contaminants may remain on some portions of the substrate
12
. The residual contaminants can interfere with subsequent substrate processing steps or with the operation of the microelectronic device formed on the substrate
12
.
Another drawback is that the brushes
50
can dry out and damage the substrate
12
. For example, if the cleaning liquid is not uniformly distributed over the surfaces
14
,
16
of the substrate
12
, portions of the brushes
50
can dry out. Alternatively, the brushes
50
can dry out between cleaning cycles. In either case, the dry brush portions can become rigid and/or abrasive and can scratch the substrate
12
, potentially damaging the substrate
12
.
Another drawback with the apparatus
10
shown in
FIG. 1
is that the contact portions
51
of the brushes
50
may entrap the contaminants entrained by the liquid as the brushes
50
and the substrate
12
move relative to each other. The contact portions
51
can press the entrapped contaminants against the surfaces of the substrate
12
and scratch or otherwise damage the substrate
12
.
Another conventional device, described in U.S. Pat. No. 5,729,856 to Jang et al., includes a bristle brush having a U-shaped cross-section to clean the edge of a semiconductor wafer mounted on a chuck. A rinsing solution is injected through spaces in the body of the brush to flow along the bristles toward the wafer. One drawback with this device is that it does not clean the entire surface of the wafer, but rather cleans only the edge of the wafer. A further drawback is that the chuck engages the center of the wafer so that the center is not accessible to the brush for cleaning.
Still another conventional device, described in U.S. Pat. No. 5,858,109 to Hymes et al., and U.S. Pat. No. 5,806,126 to de Larios et al., includes an elongated roller brush that rotates about an axis perpendicular to the axis about which the semiconductor wafer rotates. Liquid is supplied to a hollow core of the brush and is then distributed through slots or holes to the brush itself. One drawback with devices of this type is that the elongated roller brush can be relatively large and therefore expensive to manufacture. A further drawback is that it can be difficult to supply the liquid to the brush at a high flow rate because the liquid may leak from the interface between the core and the brush. Furthermore, at high liquid pressures, the liquid may be more likely to pass through portions of the brush that do not contact the wafer rather than those that do contact the wafer because the brush portions that do not contact the wafer have a low fluid flow resistance. Accordingly, the fluid may not be delivered to the wafer at the point of contact between the wafer and the brush, reducing the cleaning effectiveness of the brush.
SUMMARY OF THE INVENTION
The present invention is directed to methods and apparatuses for treating one or more surfaces of a microelectronic substrate as the substrate rotates about a substrate axis. The apparatus can include a support member having an entrance port coupled to a source of liquid and in fluid communication with at least one exit aperture. The apparatus can further include an engagement element, such as a porous pad, coupled to the support member and having at least one contact portion positioned against the exit aperture of the support member to receive liquid directly from the exit aperture. The support member and the engagement element are positionable relative to the microelectronic substrate in a contact position with the contact portion against the surface of the microelectronic substrate as the microelectronic substrate rotates relative to the support member.
In one aspect of the invention, the support member can be rotatable about a support member axis generally parallel to the substrate axis, and can include a manifold in fluid communication with the entrance port and coupled to a channel extending radially away from the support member axis. A first region of the contact portion of the engagement element can be aligned with the channel and a second region, positioned radially outwardly from the first region, can be spaced apart from the channel. Accordingly, the liquid can pass from the manifold, through the channel, into the first
Barnhart Gunnar A.
Green Greg S.
Grieger Eric K.
Dorsey & Whitney LLP
Micro)n Technology, Inc.
Rose Robert A.
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