Anti-microbubble deposition apparatus

Details Anti-microbubble deposition apparatus Anti-microbubble deposition apparatus

1999-05-28

2001-08-21

Coe, Philip R. (Department: 1746)

Cleaning and liquid contact with solids

Apparatus

With non-impelling fluid deflector or baffle other than...

C134S902000

Reexamination Certificate

active

06276379

ABSTRACT:

CLAIM OF FOREIGN PRIORITY UNDER 35 U.S.C. § 119
This patent application claims priority under 35 U.S.C. section 119 to Japanese Patent Application No. 150095/98, filed on May 29, 1998 which is incorporated herein by reference in its entirety.
FIELD OF THE INVENTION
The present invention relates to an apparatus which can greatly reduce deposition of microbubbles, generated from either chemical solution circulation systems for wet etching, wet cleaning, etc., or pure water supply systems, on product wafers during semiconductor, liquid crystals, etc. manufacturing processes.
BACKGROUND OF THE INVENTION
FIG. 1
is a flow diagram of a chemical solution circulation system used for conventional wet etching. Chemical solutions are drawn by a circulation pump
5
from an outer bath
3
of a chemical solution bath
1
and recycled to the chemical solution bath
1
through the circulation pump
5
and a filter
7
. Then, these chemical solutions reach a product wafer
4
placed in a cassette
6
from a nozzle
8
of an inner bath
2
in the chemical solution bath
1
to etch or wash the wafer as shown in FIG.
2
. Similarly, pure water is introduced into a water bath in a processing system from a pure water nozzle of the bath via a pure water line from a pure water preparing apparatus. Pure water is used to remove deposited particles or rinse chemical solutions from the product wafer. The product wafer etched or cleaned in these baths is dried by a spin drier or an IPA dryer to complete this process.
However, the chemical solutions provided to the bath may contain microbubbles generated by either the pump or variation in the pipeline diameter through which they have been circulated or other factors. Bubble-forming solutions decompose by themselves to generate microbubbles. Most microbubbles in the chemical solutions are recycled to the outer bath
3
of the chemical solution bath
1
via a deaeration line
9
provided in the housing of the filter
7
in FIG.
1
.
However, some small microbubbles pass through the filter
7
and are circulated to the inner bath
2
together with chemical solutions from the nozzle
8
of the chemical solution bath
1
, as shown in FIG.
2
. The microbubbles
10
may be deposited on the product wafer
4
. The regions of the product wafer
4
covered with microbubbles
10
are not etched or cleaned because the microbubble liquid membranes are impermeable to etching solutions or cleaning solutions. Moreover, those regions covered with microbubbles
10
are more likely to be contaminated with particles, because microbubbles attract particles floating in the chemical solution bath
1
to the microbubble liquid membranes. Bubble-forming solutions or surfactant-added chemical solutions particularly generate a larger amount of microbubbles.
Microbubbles are also generated in water washing baths due to the variation in the diameter of the pure water pipeline, the presence of a pure water flowmeter, etc. and are subsequently deposited on product wafers. Consequently, the chemical solutions may be insufficiently rinsed from the wafer surface and the product wafers may also be contaminated with particles.
However, no method currently exists to prevent microbubbles that pass through filters from being deposited on product wafers.
SUMMARY OF THE INVENTION
Microbubble deposition on product wafers can be prevented by providing means for orthogonally separating a chemical solution and microbubbles at the chemical solution nozzle of an inner bath of a chemical solution bath.
Accordingly, the anti-microbubble deposition apparatus of the present is provided on the inner wall of a etching or cleaning process bath to cover a process solution nozzle. The anti-microbubble deposition apparatus comprises an upper upright microbubble discharge tube and lower outlets for horizontally introducing a process solution into the process bath. A baffle may also be provided near the inlet of the microbubble discharge tube.


REFERENCES:
patent: 5482068 (1996-01-01), Kitahara et al.
patent: 5503171 (1996-04-01), Yokomizo et al.
patent: 136116 (1993-06-01), None

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