U.S. patent application number 09/497667 was filed with the patent office on 2001-11-22 for apparatus with a check function for controlling a flow resistance of a photoresist solution.
This patent application is currently assigned to WINSTON HSU. Invention is credited to Cheng, Chia-Wen, Cheng, Ying-Ming, Kao, Chung-Hsien, Lee, Li-Chung.
Application Number | 20010042565 09/497667 |
Document ID | / |
Family ID | 23977805 |
Filed Date | 2001-11-22 |
United States Patent
Application |
20010042565 |
Kind Code |
A1 |
Kao, Chung-Hsien ; et
al. |
November 22, 2001 |
Apparatus with a check function for controlling a flow resistance
of a photoresist solution
Abstract
The present invention provides a flow-control apparatus with a
check function for controlling the flow resistance of a photoresist
solution. The apparatus is connected to a photoresist supply
device, the photoresist supply device comprising a tank for storing
the photoresist solution, a pipe partially submerged in the
photoresist solution in the tank to transport the photoresist
solution, and a pump for drawing the photoresist solution from the
tank. The apparatus comprises a housing and a sphere. The housing
comprises a chamber, a top opening positioned at the top of the
chamber, and a bottom opening positioned at the bottom of the
chamber, wherein the top opening can be mated to an end of the pipe
or to a bottom opening of another apparatus. The sphere is moveably
set inside the chamber of the housing and increases the flow
resistance of the photoresist solution. The number of apparatuses
mounted in series with the end of the pipe can be changed to
control the flow resistance of the photoresist solution through the
pipe when drawing the photoresist solution from the tank.
Inventors: |
Kao, Chung-Hsien; (Yun-Lin
Hsien, TW) ; Cheng, Ying-Ming; (Yung-An Hsiang,
TW) ; Lee, Li-Chung; (I-Lan Hsien, TW) ;
Cheng, Chia-Wen; (Chang-Hua City, TW) |
Correspondence
Address: |
WINSTON HSU
SF. 389, FU-HO ROAD
YUNGHO CITY, TAIPEI
TW
|
Assignee: |
WINSTON HSU
|
Family ID: |
23977805 |
Appl. No.: |
09/497667 |
Filed: |
February 4, 2000 |
Current U.S.
Class: |
137/271 ;
137/529; 137/533.11 |
Current CPC
Class: |
Y10T 137/7905 20150401;
G03F 7/16 20130101; Y10T 137/5283 20150401; Y10T 137/791 20150401;
F16K 15/042 20130101; Y10T 137/88054 20150401; Y10T 137/7838
20150401 |
Class at
Publication: |
137/271 ;
137/533.11; 137/529 |
International
Class: |
F16K 015/04 |
Claims
What is claimed is:
1. An flow-control apparatus with a check function for controlling
a flow resistance of a photoresist solution, the apparatus being
connected to a photoresist supply device, the photoresist supply
device comprising a tank for storing the photoresist solution, a
pipe partially submerged in the photoresist solution in the tank to
transport the photoresist solution, and a pump for drawing the
photoresist solution out of the tank, the apparatus comprising: a
housing comprising a chamber, a top opening positioned at the top
of the chamber, and a bottom opening positioned at the bottom of
the chamber; wherein the top opening can be mated to an end of the
pipe or to a bottom opening of another housing; a sphere moveably
set inside the chamber of the housing, the sphere being used to
increase the flow resistance of the photoresist solution; wherein
the number of the apparatuses mounted in series with the end of the
pipe can be changed to control the flow resistance of the
photoresist solution through the pipe when drawing the photoresist
solution from the tank.
2. The apparatus of claim 1 wherein the portion of the pipe
submerged in the photoresist solution is substantially
vertical.
3. The apparatus of claim 2 wherein the sphere is set inside the
chamber of the housing in an up-and-down movable manner; wherein as
the pump draws the photoresist solution, the sphere moves upward
and the photoresist solution flows through the bottom opening, the
chamber, the top opening of the housing and then into the pipe; as
the pump stops drawing photoresist solution, the sphere chokes the
bottom opening to prevent back-flow of the photoresist solution
into the tank.
4. The apparatus of claim 1 wherein the sphere is removably set
inside the chamber of the housing; wherein the sphere can be
replaced with another sphere of a different density according to
the viscosity of the photoresist solution.
5. The apparatus of claim 1 wherein the sphere is made of
steel.
6. An flow-control apparatus with a check function for controlling
a flow resistance of a photoresist solution, the apparatus being
connected to a photoresist supply device, the photoresist supply
device comprising a tank for storing the photoresist solution, a
pipe partially submerged within the photoresist solution in the
tank to transport the photoresist solution, and a pump for drawing
the photoresist solution out of the tank, the apparatus comprising:
a housing comprising a chamber, a top opening positioned at the top
of the chamber, and a bottom opening positioned at the bottom of
the chamber; wherein the top opening can be mated to an end of the
pipe; a plurality of spheres inside the chamber of the housing, the
spheres being used to increase the flow resistance of the
photoresist solution; wherein the number of spheres in the chamber
is selected according to the viscosity of the photoresist solution
so that the pump draws the photoresist solution from the tank with
a predetermined pressure and the photoresist solution flows through
the pipe with a constant flow rate.
7. The apparatus of claim 6 wherein the portion of the pipe
submerged in the photoresist solution is substantially vertical,
and the spheres are stacked inside the chamber of the housing.
8. The apparatus of claim 7 wherein the spheres are stacked inside
the chamber of the housing in an up-and-down movable manner;
wherein as the pump draws the photoresist solution from the tank,
the spheres move upward and the photoresist solution flows through
the bottom opening, the chamber, the top opening of the housing,
and then into the pipe; when the pump stops drawing the photoresist
solution from the tank, one of the spheres chokes the bottom
opening to prevent back-flow of the photoresist solution into the
tank.
9. The apparatus of claim 6 wherein the top opening of the housing
can be mated to a bottom opening of another housing.
10. The apparatus of claim 6 wherein the spheres are made of steel.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an apparatus for
controlling a flow resistance of a photoresist solution, and more
particularly, to an apparatus with a check function for controlling
a flow resistance of a photoresist solution.
[0003] 2. Description of the Prior Art
[0004] In a lithographic process, electrical patterns are formed by
performing exposure and development processes to a photoresist that
has been coated onto the surface of a semiconductor wafer. The
photoresist solution is drawn from a storage tank, transported via
pipes to a nozzle and then sprayed onto the surface of the
semiconductor wafer during the coating process. The viscosity of
the photoresist solution varies from one storage tank to another as
photoresist solutions of different viscosities are required for
different manufacturing conditions. The change of viscosity affects
the flow rate of the photoresist solution. These changing flow
rates of the photoresist solution cause disproportionate coatings
of photoresist onto the surface of the semiconductor wafer and
adversely affect the yield of the subsequent fabrication process.
Hence, it is important to control the flow resistance of the
photoresist solution so as to transport the photoresist solution
with a substantially constant pressure.
[0005] Please refer to FIG. 1. FIG. 1 is a schematic diagram of a
photoresist solution supply device 10 according to the prior art.
The photoresist solution supply device 10 comprises a tank 12 for
storing the photoresist solution, a pipe 14 partially submerged in
the photoresist solution in the tank 12 to transport the
photoresist solution, a buffer tank 16 connected to the pipe 14 to
remove bubbles from the photoresist solution, a pump 24 connected
to the buffer tank 16 to draw the photoresist solution from the
buffer tank 16, a nozzle 34, a bellow 26 connected to the pump 24,
and an air cylinder 28 connected with the bellow 26. The pump 24
has compression and extension cycles, and pumps photoresist to the
nozzle 34 on the compression cycle. The bellow 26 is air-powered
and delivers the mechanical motion required to drive the pump 24.
The air cylinder 28 comprises two valves 30, 32 and the to-and-fro
movement of the bellow 26 is generated by compressed air flowing
into the air cylinder 28 from the different valves 30, 32.
[0006] The buffer tank 16 comprises an inlet 18 on its top that is
connected to the pipe 14, an outlet 22 on its bottom, and a vent 20
set at the top of the buffer tank 16 to vent bubbles from the
photoresist solution. When the photoresist solution is introduced
into the buffer tank 16, the bubbles in the photoresist solution
accumulate in the top of the buffer tank and are vented through the
vent 20 to prevent bubbles from interfering with the photoresist
coating on the surface of the semiconductor.
[0007] To move the photoresist solution from the tank 12 to the
nozzle 34, compressed air flows into the air cylinder 28 from the
valve 32. This causes the bellow 26 to pull on the pump 24, which
extends the pump 24 and causes it to draw photoresist from the tank
12. Then, compressed air flows into the air cylinder 28 from the
valve 30. This causes the bellow 26 to push on the pump 24,
compressing it and forcing the photoresist solution from the pump
26 to the nozzle 34. The buffer tank 16 draws photoresist solution
from the tank 12 through the pipe 14 to replace the photoresist
solution drawn by the pump 24.
[0008] When the tank 12 runs out of photoresist solution, the pipe
14 is extracted from the tank 12 and inserted into a new tank.
During this change, the photoresist solution in the pipe 14 drains
out and air flows in. When the pipe 14 is inserted into the new
tank, bubbles form in the photoresist solution. These bubbles are
coated onto the surface of the semiconductor wafer together with
the photoresist solution, degrading the quality of the photoresist
coating process.
[0009] The viscosity of the photoresist solution can vary from one
tank to another as photoresist solutions with differing viscosities
are required by various manufacturing conditions. The change of
viscosity affects the volume of photoresist solution transported
into the pump 24, and may also cause bubbles to form in the
photoresist solution. If the viscosity of the photoresist solution
in the new tank is less than that of the previous tank, and the
pump 24 draws the photoresist solution at the same speed, the
volume of the photoresist solution drawn into the pump 24 will
increase, leading to waste of the photoresist solution. If the flow
speed of the photoresist solution drawn into the pump 24 is too
great, bubbles will form in the photoresist solution. Therefore,
the driving pressure of air forced into the air cylinder 28 must be
changed to prevent the formation of bubbles in the photoresist
solution. The optimum driving pressure, however, is arrived at
through trial and error. The transport of photoresist solution to
the nozzle 34 may not go smoothly during the trial and error
process. This leads to uneven coatings of photoresist and decreases
the quality of the coating process.
SUMMARY OF THE INVENTION
[0010] It is therefore a primary objective of the present invention
to provide a flow-control apparatus with a check function for
controlling the flow resistance of a photoresist solution.
[0011] In a preferred embodiment, the present invention provides a
flow-control apparatus with a check function for controlling the
flow resistance of a photoresist solution. The apparatus is
connected to a photoresist supply device, the photoresist supply
device comprises a tank for storing the photoresist solution, a
pipe partially submerged in the photoresist solution in the tank to
transport the photoresist solution, and a pump for drawing the
photoresist solution out of the tank, the apparatus comprising:
[0012] a housing comprising a chamber, a top opening positioned at
the top of the chamber, and a bottom opening positioned at the
bottom of the chamber; wherein the top opening can be mated to an
end of the pipe or to a bottom opening of another housing;
[0013] a sphere moveably set inside the chamber of the housing, the
sphere being used to increase the flow resistance of the
photoresist solution;
[0014] wherein the number of the apparatuses mounted in series with
the end of the pipe can be changed to control the flow resistance
of the photoresist solution through the pipe when drawing the
photoresist solution from the tank.
[0015] It is an advantage of the present invention that the present
invention can prevent back-flow of the photoresist solution into
the tank so that air cannot flow into the pipe during the changing
of one tank for another. The present invention controls the flow
resistance of the photoresist solution by changing the number of
apparatuses connected to the pipe, the density of the sphere, the
number of spheres in the housing and the size of the sphere. A
checklist can be made that relates the viscosity of the photoresist
solution with the number of apparatuses, the density of the sphere,
the number of spheres and the size of the sphere so that the flow
resistance of the photoresist solution through the pipe can be
easily controlled, thereby increasing the quality of the coating
process.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a schematic diagram of a photoresist solution
supply device according to the prior art.
[0017] FIG. 2 is a schematic diagram of a photoresist solution
supply device according to the present invention.
[0018] FIG. 3 is a sectional diagram of an apparatus for
controlling the flow resistance according to the present
invention.
[0019] FIG. 4 is a sectional diagram of apparatuses in series for
controlling the flow resistance according to the present
invention.
[0020] FIG. 5 is a diagram of an apparatus with a plurality of
spheres for controlling the flow resistance according to the
present invention.
[0021] FIG. 6 is a diagram of an apparatus with a plurality of
smaller spheres for controlling the flow resistance according to
the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0022] Please refer to FIG. 2. FIG. 2 is a schematic diagram of a
photoresist solution supply device 40 according to the present
invention. A flow-control apparatus 60 of the present invention is
used to modify the flow resistance of the photoresist solution, and
is connected to the photoresist supply device 40. The apparatus
controls the volume of photoresist that is transported to a nuzzle
58. The photoresist solution supply device 40 comprises a tank 42
for storing the photoresist solution, a pipe 44 partially submerged
in the photoresist solution in the tank 42 to transport the
photoresist solution, a pump 46 for drawing the photoresist
solution out of the tank 42, a bellow 48 connected with the pump 46
to drive the pump, and an air cylinder 50 connected with the bellow
48 for powering and controlling the bellow 48. The air cylinder 50
comprises two valves 52, 54 and the to-and-fro movement of the
bellow 48 results from pressurized air being introduced into the
air cylinder 50 through the valves 52, 54. The pipe 44, submerged
in the photoresist solution, is substantially vertical.
[0023] Please refer to FIG. 3. FIG. 3 is a schematic diagram of the
flow-control apparatus 60 for controlling the flow resistance of
the photoresist solution according to the present invention. The
apparatus 60 comprises a housing 62 and a sphere 70 made of steel.
Although steel is disclosed here as an example, it should be
understood that other materials may also be used to form the sphere
70. The housing 62 comprises a chamber 64, a top opening 66
positioned at the top of the chamber 64, and a bottom opening 68
positioned at the bottom of the chamber 64. The top opening 66 can
be mated to an end of the pipe 44 or to the bottom opening of
another flow-control apparatus. The sphere 70 is moveably set
inside the chamber 42 of the housing 62, and it increases the flow
resistance of the photoresist solution.
[0024] To move photoresist from the tank 42 to the nozzle 48,
pressurized air flows into the air cylinder 50 from the valve 54
and causes the bellow 48 to extend. This draws the photoresist
solution out of the tank 42 and into the pump 46. Pressurized air
then flows into the air cylinder 50 from the valve 52 and causes
the bellow 48 to contract. This forces the photoresist solution to
flow from the pump 46 to the nozzle 58.
[0025] As the pump 46 draws the photoresist solution from the tank
42, the sphere 70 moves upward. The photoresist solution flows
through the bottom opening 68, the chamber 64, the top opening 66,
and then into the pipe 44. When the pump 46 stops drawing
photoresist solution, the sphere 70 drops down and chokes the
bottom opening 68. This prevents back-flow of photoresist solution
into the tank 42. When the tank 42 runs out of photoresist, the
pipe 44 is extracted from the tank 42 and inserted into a new tank.
During this change, because of the choking action of the sphere 70,
the photoresist solution in the pipe 44 does not flow out and air
does not flow in. Consequently, the formation of bubbles is
avoided.
[0026] Please refer to FIG. 4. FIG. 4 is a schematic diagram of
flow-control apparatuses 60 in series with a flow-control apparatus
72 according to the present invention. Because the top opening 66
of the apparatus 60 can be mated to the end of the pipe 44 or to
the bottom opening of another apparatus, the number of apparatuses
60 mounted in series with the end of the pipe 44 can be changed to
control the flow resistance of the photoresist solution through the
pipe 44 when drawing the photoresist solution from the tank 42.
When the photoresist solution is exchanged for a new photoresist
solution with a lesser viscosity, an apparatus 72, or more than one
apparatus, can be mounted to the bottom opening 68 of the apparatus
60 to increase the flow resistance of the new photoresist so that
it equals the flow resistance of the previous photoresist through
the single apparatus 60. The pump 46 can then draw the new
photoresist solution from the tank 42 with a predetermined pressure
without changing the driving pressure of air delivered to the air
cylinder 50, and the photoresist solution flows through the pipe 44
with a constant flow rate.
[0027] Alternatively, the sphere 70 can be replaced with another
sphere with a different density to compensate for the changed
viscosity of the new photoresist solution. For example, when using
a less viscous solution, a new sphere 70 with a greater density can
replace the old sphere in the chamber 64, and thus ensure a
constant flow resistance for both types of photoresist solution. In
this manner, bubble-formation due to an excessive flow rate of the
solution is avoided, without needing to adjust the operating
pressure of the pump 46.
[0028] Please refer to FIG. 5. FIG. 5 is a schematic diagram of
another embodiment of a flow-control apparatus 80 according to the
present invention. The housing 82 of the apparatus 80 can be
replaced by a larger one that holds a plurality of spheres 70 to
increase the flow resistance of the photoresist solution. FIG. 5
shows three spheres 70 moveably stacked inside the chamber 84 of
the housing 82. These spheres are used to increase the flow
resistance of the photoresist solution through the pipe 44 when
drawing the photoresist solution from the tank 42. Although FIG. 5
depicts three spheres in the housing, it should be understood that
the chamber 84 is designed to allow more than three spheres to be
stacked to achieve the required flow resistance.
[0029] As in the above art, when the pump 46 draws the photoresist
solution from the tank 42, the spheres 70 move upward and the
photoresist solution flows through the bottom opening 88. It then
flows through the chamber 84, the top opening 86 of the housing 82,
and into the pipe 44. If the pump 46 stops drawing photoresist
solution from the tank 42, the drop in pressure will cause one of
the spheres 70 to move downward and choke the bottom opening 88.
This prevents a back-flow of photoresist solution into the tank
42.
[0030] Please refer to FIG. 6. FIG. 6 is a schematic diagram of the
apparatus 80 using smaller spheres 90 according to the present
invention to achieve the proper flow resistance. There are nine
spheres 90 moveably stacked inside the chamber 84 of the housing
82. They are used to increase the flow resistance of the
photoresist solution through the pipe 44 when drawing the
photoresist solution from the tank 42. Again, the depiction of nine
spheres is arbitrary. More or less may be used to achieve the
required flow resistance. As the pump 46 draws the photoresist
solution from the tank 42, the spheres 90 move upward and the
photoresist solution flows through the bottom opening 88. It then
flows into the chamber 84, through the top opening 86 of the
housing 82, and into the pipe 44. When the pump 46 stops drawing
the photoresist solution from the tank 42, one of the spheres 90
will choke the bottom opening 88 to prevent back-flow of the
photoresist solution into the tank 42.
[0031] Replacing the spheres 70 with the smaller spheres 90 enables
the flow resistance of the photoresist solution to be controlled
more precisely. If there is not a dramatic change in the viscosity
of the photoresist solution, adding a sphere 70 to the chamber 84
of the housing 82, or removing one, can result in an
over-adjustment. That is, the flow resistance may be excessively
increased by adding a sphere 70, or excessively decreased by
removing a sphere 70. This problem is resolved by adding a proper
number of smaller spheres 90 to the chamber 84 according to the
viscosity of the photoresist solution. Consequently, the number of
the spheres 90 inside the chamber 84 is chosen according to the
viscosity of the photoresist solution so that the pump draws the
photoresist solution from the tank 42 with a predetermined pressure
and the photoresist solution flows through the pipe 44 with a
constant flow rate. Similarly, the flow resistance of the
photoresist solution can also be modified by replacing the spheres
with those of a different density, as required by the viscosity of
the photoresist solution.
[0032] Compared to the prior art problem of bubble-formation in a
photoresist solution, the present invention prevents back-flow of
the photoresist solution into the tank so that air can not flow
into the pipe when changing holding tanks. The present invention
controls the flow resistance of the photoresist solution by
changing the number of flow-control apparatuses linked together in
series with the pipe, by changing the density of the spheres used
in the flow control apparatus, by changing the number of spheres
used in the housing, and by changing the size of the spheres. A
list can be made that relates the viscosities of the various
photoresist solutions to the best arrangement of flow-control
apparatuses to ensure a proper flow rate. This list could include
the number of apparatuses linked together in series with the pipe,
the density of the spheres used inside the apparatus, the number of
spheres used for each apparatus, and the size of the spheres.
[0033] skilled in the art will readily observe that numerous
modifications and alterations of the device may be made while
retaining the teachings of the invention. Accordingly, the above
disclosure should be construed as limited only by the metes and
bounds of the appended claims.
* * * * *