Drying and gas or vapor contact with solids – Process – Gas or vapor contact with treated material
Reexamination Certificate
2001-05-15
2003-02-18
Wilson, Pamela (Department: 3749)
Drying and gas or vapor contact with solids
Process
Gas or vapor contact with treated material
C034S448000, C034S470000, C034S509000, C034S068000, C034S074000, C034S632000
Reexamination Certificate
active
06519869
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a method and an apparatus for drying semiconductor wafers, and more particularly relates to a method and an apparatus for drying semiconductor wafers by using an IPA (isopropyl alcohol) drying apparatus.
2. Description of the Prior Art
Recently, IPA dryers have been used for the drying of semiconductor wafers, because, compared to a spin dryer, the semiconductor wafers incur less mechanical damage and a cleaner semiconductor wafer surface is obtainable.
A typical IPA drying apparatus is shown in FIG.
1
. An IPA drying apparatus has an IPA dryer tank
100
to isolate the semiconductor wafers to reduce the water content contained in the semiconductor wafers. A plurality of semiconductor wafers
110
, for example which have been washed after a wet etching step for example, are delivered by a mechanical arm to the IPA dryer tank
100
for drying and are supported by a holder
110
. An IPA solution
120
is contained in the IPA dryer tank
100
and is heated by a heater
114
to its boiling point to generate an IPA vapor
122
in the IPA dryer tank
100
. There are cooling or condensation coils
130
surrounding and disposed on the inner peripheral surface of the IPA dryer tank
100
.
The IPA vapor
122
coats on semiconductor wafers
110
and combined with water thereon to become an IPA co-solution. When semiconductor wafers
110
rise to the level of cooling coils
130
, the IPA co-solution is evaporated and water is removed from semiconductor wafers
110
at the same time. The IPA dryer tank
100
comprises a collecting tray
132
below cooling coils
130
which is mounted on the inner peripheral surface of the IPA dryer tank
100
, to collect drips from cooling coils
130
and drain out from an outlet
134
. The IPA dryer tank
100
further comprises an outlet
136
to exhaust the IPA vapor
122
.
However, the IPA vapor
122
is continuously generated in the IPA dryer tank
100
, and the IPA vapor
122
is continuously coating on semiconductor wafers
110
. The disadvantage of the current IPA drying apparatus is that the continuously generated IPA vapor may contaminate dried semiconductor wafers again. Furthermore, the continuously generated IPA vapor causes production costs to increase.
SUMMARY OF THE INVENTION
The primary object of the invention is to provide a method for drying semiconductor wafers using an IPA drying apparatus.
Another object of the invention is to provide an apparatus for drying semiconductor wafers.
A further object of the invention is to easily control the input amount of the IPA vapor and increase the safety of the process.
In order to achieve the previous objects of the invention, a method comprising the following essential steps is provided. First, a solution is evaporated to generate a vapor, wherein the solution can generate a co-solution with water and the co-solution can evaporate at a temperature lower than 100. Then, a dryer tank is provided. Next, the vapor is piped to a porous hollow plate in the dryer tank. Last, at least one wafer is dried in the dryer tank, wherein the vapor is evenly diffused from the hollow porous plate.
Another embodiment is an apparatus for drying semiconductor wafers and the apparatus comprises the following elements. First, a vapor generator is used to generate a vapor. Second, a pipe is used to transfer the vapor, wherein one side of the pipe is connected to the vapor generator. Third, a dryer tank is used for drying wafers, wherein a porous hollow plate is on a bottom of the dryer tank and is connected to another side of the pipe. The porous hollow plate has a porous surface faced up in the dryer tank and the vapor is evenly diffused from the porous surface.
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Powell Goldstein Frazer & Murphy LLP
United Microelectronics Corp.
Wilson Pamela
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