Cleaning and liquid contact with solids – Processes – Using solid work treating agents
Reexamination Certificate
2002-12-23
2004-05-11
Markoff, Alexander (Department: 1746)
Cleaning and liquid contact with solids
Processes
Using solid work treating agents
C015S077000, C015S088300, C015S102000
Reexamination Certificate
active
06733596
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to the fabrication of semiconductor devices and, more particularly, to cleaning semiconductor substrates.
2. Description of the Related Art
As is well known to those skilled in the art, the fabrication of semiconductor devices involves numerous processing operations. These operations include, for example, impurity implants, gate oxide generation, inter-metal oxide depositions, metallization depositions, photolithography patterning, etching operations, chemical mechanical polishing (CMP), etc. Typically, these operations generate contaminants such as particles and residue, which are adhered or absorbed by the wafer surfaces. It is well established that contaminants should be removed from wafer surfaces, as the existence of such contaminants has detrimental effects on the performance of the integrated circuit devices. To achieve this task, wafer surfaces are cleaned as a result of which contaminants such as adhered particles and absorbed compounds (e.g., chemicals) are removed from wafer surfaces.
Normally, double-sided cleaning processing tools are implemented to clean wafer surfaces.
FIG. 1
illustrates a cross sectional view of a double-sided horizontal wafer scrubber
100
designed to clean a top surface and bottom surface of a wafer
102
, in accordance with the prior art. As shown, the wafer scrubber
100
includes a top brush
104
a
and a bottom brush
104
b
, each mounted on a corresponding brush core
106
a
and bottom brush core
106
b
. Each of the top brush core
106
a
and the bottom brush core
106
b
includes a top shaft
108
a
and a bottom shaft
108
b
, each connected to a fluid inlet (not shown in FIG.
1
). As shown, the outer surface of top and bottom brushes
104
a
and
104
b
are covered with a plurality of nodules
104
a
and
105
b
, respectively.
The wafer
102
is shown to be engaged by a pair of rollers
114
a
and
114
b
. As can be seen, the wafer
102
is held horizontally by the pair of rollers
114
a
and
114
b
and top and bottom brushes
104
a
and
104
b
. Top and bottom surfaces of the wafer
102
are scrubbed, respectively, by top and bottom brushes
104
a
and
104
b
, which rotate in top and bottom brush rotation directions
110
a
and
110
b
, correspondingly. The rollers
114
a
and
114
b
rotate while holding the wafer
102
, causing the wafer
102
to rotate. The wafer
102
is cleaned as top and bottom brushes
104
a
and
104
b
come in contact with top and bottom surfaces of the wafer
102
, removing the contaminants.
Normally, each brush core
108
a
and
108
b
is connected to a respective fluid inlet designed to supply fluid into the brush cores
108
a
and
108
b
. Although not shown, each top and bottom brush core
106
a
and
106
b
has a plurality of holes thereon allowing fluid to exit top and bottom brush cores
106
a
and
106
b
so as to flush top and bottom brushes
104
a
and
104
b
, respectively.
To scrub and rinse wafer top and bottom surfaces thoroughly so as to remove any remaining contaminants, chemicals are initially supplied through the brush (TTB), saturating top and bottom brushes
104
a
and
104
b
. Wafer top and bottom surfaces are then scrubbed by top and bottom brushes
104
a
and
104
b
for a desired time. Then, top and bottom surfaces of the wafer
102
are rinsed TTB. That is, top and bottom brushes
104
a
and
104
b
are flushed and saturated with DI water so as to eliminate scrubbing chemicals in top and bottom brushes
104
a
and
104
b
as well as disposing of any contaminant remaining on top and bottom surfaces of the wafer
102
. The rinse operation thereafter continues until any and all contaminants remaining on top and bottom surfaces of the wafer have been removed. At this point, the cleaned wafer is removed from the brush scrubber
100
, allowing the next wafer to be placed on the rollers
114
a
and
114
b
. In this fashion, each wafer is scrubbed and rinsed in the prior art brush scrubber
100
.
Repeatedly flushing top and bottom brushes
104
a
and
104
b
with chemicals followed by rinsing of the chemicals out of top and bottom brushes
104
a
and
104
b
using de-ionized water is not without negative consequences. For instance, a significant amount of chemicals is wasted during each and every brush scrubbing operation. The brushes arc saturated with chemicals to perform the scrubbing operation. Immediately thereafter the brushes are rinsed with DI water, ultimately resulting in wasting a substantial amount of chemicals, overall. In addition to wasting chemicals, the pH of top and bottom brushes
104
a
and
104
b
is repeatedly and constantly oscillating, undesirably creating a constant non-equilibrium in top and bottom brushes
104
a
and
104
b.
Another negative effect of TTB scrubbing and rinse operation is reintroduction of contaminants onto the wafer top and bottom surfaces. For instance, residues remaining in top and bottom brushes are re-introduced into the rinsing interface by the rinse fluid applied TTB. Additionally, chemicals in top brush drip on to the top surface of the wafer, recontaminating the wafer top surface having the active components, damaging the wafers and significantly reduce wafer throughput.
In view of the foregoing, there is a need for an improved semiconductor processing apparatus and methodology capable of minimizing wasting of chemicals during cleaning operation while increasing wafer throughput through preventing recontamination of wafer surfaces.
SUMMARY OF THE INVENTION
Broadly speaking, the present invention fills these needs by providing an apparatus and methodology capable of substantially minimizing fluids used during substrate cleaning operations while increasing wafer throughput. In one embodiment, top and bottom surfaces of the wafers are cleaned in a brush scrubber-rinse module. In one embodiment, top and bottom brushes of the brush scrubber-rinse module saturated with scrubbing fluid are implemented to scrub wafer top and bottom surfaces through the brush (TTB). Top and bottom brushes are squeezed, eliminating excess scrubbing fluid. Top and bottom surfaces of the wafer are then rinsed using a rinse fluid introduced onto the wafer top and bottom surfaces through respective rinse nozzles.
It should be appreciated that the present invention can be implemented in numerous ways, including as a process, an apparatus, a system, a device, or a method. Several inventive embodiments of the present invention are described below.
In one embodiment, a method for cleaning top and bottom surfaces of a semiconductor substrate is provided. The method includes scrubbing a top surface of the semiconductor wafer with a top brush and a bottom surface of the semiconductor substrate with a bottom brush. The top brush and the bottom brush are saturated and supplied with a scrubbing fluid. The method also includes squeezing the top brush and the bottom brush so as to press out excess scrubbing fluid by continuing to apply the top brush against the top surface and the bottom brush against the bottom surface of the semiconductor substrate, but without supplying the scrubbing fluid. The method further includes moving the top brush away from the top surface of the semiconductor substrate and the bottom brush from the bottom surface of the semiconductor substrate. Also included is rotating the top brush to prevent dripping onto the top surface of the semiconductor substrate. The method also includes rinsing the top and bottom surfaces of the semiconductor substrate using a rinse fluid while continuing to rotate the top brush that was squeezed to press out the excess scrubbing fluid.
In another embodiment, a method for cleaning a semiconductor substrate is provided. The method includes scrubbing a top surface of the semiconductor substrate with a top brush and a bottom surface of the semiconductor substrate with a bottom brush. The top brush and the bottom brush are saturated with a scrubbing fluid. Also included is squeezing the top brush and the bottom brush so as to pres
Mikhaylichenko Katrina
Ravkin Michael
Chaudhry Saeed
Markoff Alexander
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