U.S. patent application number 10/773615 was filed with the patent office on 2004-12-09 for cooling apparatus for wafer baking plate.
This patent application is currently assigned to SAMSUNG ELECTRONICS CO., LTD.. Invention is credited to Kim, Sang-Kap, Kim, Tae-Gyu, Lee, Dong-Woo, Lee, Jin-Sung, Shin, Dong-Hwa.
Application Number | 20040244945 10/773615 |
Document ID | / |
Family ID | 33487881 |
Filed Date | 2004-12-09 |
United States Patent
Application |
20040244945 |
Kind Code |
A1 |
Lee, Jin-Sung ; et
al. |
December 9, 2004 |
Cooling apparatus for wafer baking plate
Abstract
A cooling apparatus for a wafer baking plate is provided. The
wafer baking plate has a support plate for supporting a wafer, a
heater under the support plate, and a heat transfer plate
interposed between the support plate and the heater, for
transferring heat. In the cooling apparatus, a hollow bore is
formed in the heat transfer plate of the wafer baking plate and
partially filled with a liquid working fluid. A cooling pipe is
laid in the heat transfer plate, for circulating a cooling medium.
The wafer baking plate is cooled down via the working fluid,
stabilizing its temperature distribution. Therefore, the product
yield of wafers is increased.
Inventors: |
Lee, Jin-Sung; (Seoul,
KR) ; Lee, Dong-Woo; (Seoul, KR) ; Kim,
Tae-Gyu; (Hwasung-gun, KR) ; Kim, Sang-Kap;
(Osan-shi, KR) ; Shin, Dong-Hwa; (Suwon-shi,
KR) |
Correspondence
Address: |
DILWORTH & BARRESE, LLP
333 EARLE OVINGTON BLVD.
UNIONDALE
NY
11553
US
|
Assignee: |
SAMSUNG ELECTRONICS CO.,
LTD.
GYEONGGI-DO
KR
|
Family ID: |
33487881 |
Appl. No.: |
10/773615 |
Filed: |
February 6, 2004 |
Current U.S.
Class: |
165/47 ;
165/58 |
Current CPC
Class: |
F28F 3/12 20130101; H01L
21/67109 20130101; F28D 15/02 20130101 |
Class at
Publication: |
165/047 ;
165/058 |
International
Class: |
F24H 003/00; F25B
029/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 4, 2003 |
KR |
36021/2003 |
Claims
1. A cooling apparatus for a wafer baking plate having a support
plate for supporting a wafer, a heater under the support plate, and
a heat transfer plate interposed between the support plate and the
heater, for transferring heat, comprising: a hollow bore formed in
the heat transfer plate and partially filled with a liquid working
fluid; and a cooling pipe laid in the heat transfer plate, for
circulating a cooling medium
2. The cooling apparatus of claim 1, wherein the cooling pipe is
laid in the hollow bore of the heat transfer plate and disposed in
the working fluid which is liquid at room temperature.
3. The cooling apparatus of claim 1, wherein a groove is formed in
the bottom of the hollow bore and the cooling pipe is laid in the
groove.
4. The cooling apparatus of claim 1, wherein the cooling pipe is
laid outside the hollow bore.
5. The cooling apparatus of claim 1, wherein the cooling pipe
includes a first pipe laid in the hollow bore and a second pipe
laid outside the hollow bore.
6. The cooling apparatus of claim 1, wherein a cross-section of the
cooling pipe is one of circular, oval, and polygonal.
Description
PRIORITY
[0001] This application claims priority under 35 U.S.C. .sctn. 119
to an application entitled "Cooling Apparatus for Wafer Baking
Plate" filed in the Korean Intellectual Property Office on Jun. 4,
2003 and assigned Serial No. 2003-36021, the contents of which are
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates generally to a wafer
fabricating apparatus, and in particular, to an apparatus for
cooling a baking plate on which a photoresist layer deposited on a
wafer is baked.
[0004] 2. Description of the Related Art
[0005] In general, semiconductor device fabrication involves
photolithography. For photolithography, a photoresist layer is
formed by depositing a photoresist on a wafer, which is then
patterned by exposing the photoresist layer to a predetermined
light source such as a laser. The wafer is heated and baked
repeatedly during this process.
[0006] Heating is performed in four steps in the process of
semiconductor device fabrication: (1) pre-baking for removing
organic materials or foreign materials from a wafer before
formation of a photoresist layer; (2) soft baking for drying the
photoresist layer deposited on the wafer for fixing the layer to
the wafer; (3) post-exposure baking for exposing the photoresist
layer to a light source and then heating the photoresist layer; and
(4) hard baking for tightly attaching a pattern resulting from
development of the exposed photoresist layer onto the wafer. The
wafer heating is carried out at various temperatures according to
the type of photoresist and may be varied during the heating
steps.
[0007] A wafer baking plate for setting various heating
temperatures is disclosed in Japanese Patent Application No.
1999-205079 filed on Jul. 19, 1999. The wafer baking plate has a
path for running a cooling medium therein to cool the baking
plate.
[0008] However, conventional fabrication apparatuses for the wafer
baking plate are slow in transferring heat and typically take a
long time to achieve a uniform temperature distribution for the
wafer baking plate. Even if the baking plate is cooled down
rapidly, uniform temperature distribution takes a long time,
thereby reducing wafer product yield.
SUMMARY OF THE INVENTION
[0009] It is, therefore, an object of the present invention to
provide a fabrication apparatus for a wafer baking plate, which
shortens the time required to cool down the wafer baking plate and
rapidly stabilizes temperature distribution.
[0010] The above object is achieved by a fabrication apparatus for
a wafer baking plate having a support plate for supporting a wafer,
a heater under the support plate, and a heat transfer plate
interposed between the support plate and the heater, for
transferring heat. In the fabrication apparatus, a hollow bore is
formed in the heat transfer plate of the wafer baking plate and
partially filled with a liquid working fluid. A cooling pipe is
laid in the heat transfer plate, for circulating a cooling
medium.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The above and other objects, features and advantages of the
present invention will become more apparent from the following
detailed description, when taken in conjunction with the
accompanying drawings in which:
[0012] FIG. 1 is a perspective view of a wafer baking plate
according to a preferred embodiment of the present invention;
[0013] FIG. 2 is a cross-sectional view of the wafer baking plate,
taken along line A-A' illustrated in FIG. 1;
[0014] FIG. 3 is a partial enlarged sectional view of the wafer
baking plate illustrated in FIG. 2;
[0015] FIG. 4 is a cross-sectional view of the wafer baking plate,
taken along line B-B' illustrated in FIG. 2;
[0016] FIG. 5 is a cross-sectional view of an embodiment of the
wafer baking plate illustrated in FIG. 2 with a cooling pipe
according to the present invention;
[0017] FIG. 6 is a cross-sectional view of another embodiment of
the wafer baking plate illustrated in FIG. 2 with a cooling pipe
according to the present invention;
[0018] FIG. 7 is a cross-sectional view of a third embodiment of
the wafer baking plate illustrated in FIG. 2 with a cooling pipe
according to the present invention;
[0019] FIG. 8 is a cross-sectional view of a fourth embodiment of
the wafer baking plate illustrated in FIG. 2 with a cooling pipe
according to the present invention;
[0020] FIGS. 9A, 9B and 9C illustrate cross-sectional shapes of a
cooling pipe for the wafer backing plate illustrated in FIG. 2;
[0021] FIG. 10 depicts a heating operation for the wafer baking
plate illustrated in FIG. 2;
[0022] FIG. 11 depicts a cooling operation for the wafer baking
plate illustrated in FIG. 2;
[0023] FIG. 12 illustrates cooling curves of the wafer baking plate
illustrated in FIG. 1; and
[0024] FIG. 13 illustrates a cooling curve of a wafer baking plate
according to a conventional natural cooling method.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0025] Preferred embodiments of the present invention will be
described herein below with reference to the accompanying drawings.
In the following description, well-known functions or constructions
are not described in detail since they would obscure the invention
in unnecessary detail.
[0026] FIG. 1 is a perspective view of a wafer baking plate 100
according to a preferred embodiment of the present invention, FIG.
2 is a cross-sectional view of the wafer baking plate 100, taken
along line A-A' illustrated in FIG. 1, FIG. 3 is a partial enlarged
cross-sectional view of the wafer backing plate 100, and FIG. 4 is
a cross-sectional view of the wafer baking plate 100, taken along
line B-B' illustrated in FIG. 2. As illustrated in FIGS. 1 to 4,
the wafer baking plate 100 is comprised of a support plate 101, a
heater 102 under the support plate 101, and a heat transfer plate
103 between the support plate 101 and the heater 102. The wafer
baking plate 100 includes a fabrication apparatus having a cooling
pipe 105 laid inside the heat transfer plate 103.
[0027] In the wafer baking plate 100, a mounting surface 111 is
defined on the support plate 101 and guide protrusions 113 are
formed around the mounting surface 111, for preventing movement of
a wafer. The heat transfer plate 103 can be formed integrally with
the support plate 101. The heat transfer plate 103 is a medium that
transfers heat from the heater 102 to the support plate 101 and has
a hollow bore or track 131 partially filled with a liquid working
fluid 139 therein. The hollow bore 131 can be segmented by a
plurality of separators 133 inside the heat transfer plate 103. As
illustrated in FIG. 4, the separators 133 are concentrically
arranged within the heat transfer plate 103.
[0028] The cooling pipe 105 introduces a cooling medium, circulates
it around the heat transfer plate 103, and then discharges it
outside the plate 100. The cooling pipe 105 is laid spirally along
the hollow bore 131 of the heat transfer plate 103 as illustrated
in FIG. 4. The cooling pipe 105 has an inlet and an outlet close to
each other. Preferably cooling medium in and out paths are parallel
in order to offset the temperature difference between the injected
cooling medium and the discharged cooling medium and thus maintain
a uniform temperature distribution across the wafer baking plate
100. While a single pipeline is used as the cooling pipe 105, a
plurality of pipelines can be installed to thereby circulate more
cooling medium at a given time and shorten cooling time.
[0029] As illustrated in FIGS. 5 and 6, the cooling pipe 105 can be
laid simply in the hollow bore 131 (FIG. 5) or in a groove 137
(FIG. 6) formed in the bottom of the hollow bore 131. The cooling
pipe 105 can also be buried under the hollow bore 131 as
illustrated in FIG. 7, or a plurality of cooling pipes 105 can be
installed, such as the two shown in FIG. 8, with one in the hollow
bore 131 and the other buried under the hollow bore 131.
[0030] Referring to FIGS. 9A, 9B and 9C, the cross-section of the
cooling pipe 105 can be circular, oval or polygonal. To improve
heat transfer efficiency, cooling fins or wrinkles may be formed on
the inner and outer circumferential surfaces of the cooling pipe
105.
[0031] Referring to FIG. 10, when the heater 102 emits heat, as
indicated by reference character B, the heat is transferred to the
heat transfer plate 103 and the working fluid 139 is vaporized as
indicated by reference character C. The vaporized working fluid
transfers heat as indicated by reference character D, returns to a
liquid state, and then receives heat from the heater 102 again. The
phase transition of the working fluid 139 occurs in a closed cycle
within the hollow bore 131 and the heat from the heater 102 is
effectively transferred to the support plate 101 via the vaporized
working fluid 139. Since the heat transfer is carried out through
the phase transition of the working fluid 139, temperature
distribution is uniform across the support plate 101.
[0032] Preferably, the interior of the cooling pipe 105 is vacuumed
or filled with air during the heating. If a liquid such as a
cooling medium is filled in the cooling pipe 105, the heat from the
heater 102 is not effectively transferred to the support plate 101,
and only heats the liquid in the cooling pipe 105.
[0033] Cooling of the baking plate 100 will be described with
reference to FIG. 11. To rapidly cool the baking plate 100, the
cooling medium is circulated through the cooling pipe 105. For the
cooling medium, water can be used. Along with the circulation of
the cooling medium, the heat from the support plate 101 is absorbed
by the cooling pipe 105 as indicted by reference character D', and
the heat of the heat transfer plate 103 and the heater 102 is
absorbed by the cooling pipe 105 as indicated by reference
characters C' and B'. As a result, heat around the cooling pipe 105
is absorbed by the cooling medium of the cooling pipe 105. The
cooling medium is continuously injected into the cooling pipe 105
and circulated around the heat transfer plate 103, thus cooling the
baking plate 100.
[0034] Similarly, the heat of the baking plate 100 is absorbed by
the cooling pipe 105 through the working fluid 139, resulting in a
uniform temperature distribution across the support plate 101 and
remarkably reducing cooling time.
[0035] FIG. 12 shows a graph 109 illustrating cooling curves when
the cooling apparatus for the baking plate 100, illustrated in FIG.
4, operates. The graph 109 illustrates temperature change while the
average temperature of the baking plate 100 falls from 150.degree.
C. to 100.degree. C. in the case where a cooling medium is
circulated at 18.degree. C. at 1.51/min. Reference numeral {circle
over (1)} denotes a curve showing the change of the average
temperature of the baking plate 100 in time and reference numeral
{circle over (2)} denotes a curve showing the change of the maximum
temperature deviation of the baking plate 100 in time.
[0036] Referring to FIG. 12, it is noted from curves {circle over
(1)} and {circle over (2)} that the average temperature of the
baking plate 100 drops to 100.degree. C. 15 seconds after the
fabrication apparatus starts to operate in the present invention.
Then the cooling water injection is discontinued and the cooling
pipe is filled with air. Thirty seconds later, the temperature
deviation of the baking plate 100 is reduced markedly, and 50
seconds later, its temperature distribution is stabilized.
[0037] FIG. 13 shows a graph 209 illustrating temperature change in
a wafer baking plate according to conventional natural cooling
method. While the natural cooling leads to a relatively uniform
temperature distribution on the wafer baking plate during cooling,
45 minutes is taken to cool the wafer baking plate from 150.degree.
C. to 100.degree. C., thereby significantly decreasing product
yield, as illustrated in FIG. 13. On the contrary, the fabrication
apparatus of the present invention rapidly cools the baking plate,
achieving a uniform temperature distribution only in 50
seconds.
[0038] In accordance with the present invention as described above,
the fabrication apparatus for a wafer baking plate has a cooling
pipe laid in a heat transfer plate partially filled with a liquid
working fluid, for rapid cooling of the wafer baking plate. Since
the heating and cooling of the baking plate is carried out via the
working fluid, the temperature is uniform across the baking plate.
Furthermore, the maintenance of the uniform temperature
distribution during heating or cooling the wafer baking plate
increases product yield.
[0039] While the invention has been shown and described with
reference to a certain preferred embodiment thereof, it will be
understood by those skilled in the art that various changes in form
and details may be made therein without departing from the spirit
and scope of the invention as defined by the appended claims.
* * * * *