System and method for control of fluid pressure
View Patent ↗Embodiments of the present invention are related to a pumping system that accurately dispenses fluid using a multiple stage (“multi-stage”) pump. More particularly, embodiments of the present invention provide for control of a feed stage pump to regulate fluid pressure at a downstream dispense stage pump. According to one embodiment of the present invention, a pressure sensor at the dispense stage pump determines the pressure in a dispense chamber. When the pressure reaches a predefined threshold, the dispense stage pump can begin to increase the available volume of the dispense chamber, thereby causing the pressure in the dispense chamber to drop. As the pressure decreases/increases at the downstream pump, the pressure applied by the upstream pump can bed increased/decreased.
1. A method for controlling fluid pressure in a multiple stage pump comprising:
operating a feed pump to reduce a volume of a feed chamber at a first predetermined rate;
opening a barrier valve to allow a fluid in the feed chamber to enter a dispense chamber while keeping an outlet valve closed so that none of the fluid entering the dispense chamber is dispensed;
taking a first pressure measurement of the fluid in the dispense chamber using a pressure sensor disposed to measure pressure in the dispense chamber;
determining whether the first pressure measurement is greater than a predetermined pressure;
in response to the first pressure measurement being greater than said predetermined pressure, operating a dispense pump to increase a volume of the dispense chamber at a second predetermined rate;
taking a second pressure measurement of the fluid in the dispense chamber using the pressure sensor, wherein the second pressure measurement is taken while the dispense pump is operating to increase the volume of the dispense chamber;
determining whether the second pressure measurement is greater than the predetermined pressure;
in response to determining that the second pressure measurement is greater than the predetermined pressure, operating the feed pump at a decreased speed;
in response to determining that the second pressure measurement is not equal to or greater than the predetermined pressure, operating the feed pump at an increased speed;
determining whether the operation of the dispense pump has caused the volume of the dispense chamber to reach a predetermined volume;
in response to determining that the volume of the dispense chamber has not reached the predetermined volume, repeating the method from the step of measuring the second pressure; and
in response to determining that the volume of the dispense chamber has reached the predetermined volume, stopping the operation of the feed pump and the dispense pump.
2. The method of claim 1 , wherein the fluid has a viscosity of less than 5 centipoise.
3. The method of claim 1 , further comprising;
closing the barrier valve;
opening the outlet valve; and
operating the dispense pump to dispense fluid onto a wafer.
4. The method of claim 1 , wherein operating the feed pump comprises operating a stepper motor.
5. The method of claim 4 , wherein operating the dispense pump comprises operating a permanent-magnet synchronous motor.
6. The method of claim 1 , further comprising filtering the fluid through a filter between the feed pump and the dispense pump.
7. A multiple stage pump comprising:
a feed pump comprising:
a feed chamber;
a first diaphragm movable in the feed chamber;
a first lead screw to move the first diaphragm;
a first motor coupled to the first lead screw to rotate the first lead screw;
a dispense pump fluidly coupled to the feed pump, the dispense pump comprising:
a dispense chamber;
a second diaphragm movable in the dispense chamber;
a second lead screw to move the second diaphragm;
a second motor coupled to the second lead screw to rotate the second lead screw;
a filter disposed in a fluid flow path between the feed pump and the dispense pump;
an inlet valve;
an isolation valve;
a barrier valve;
an outlet valve;
a pressure sensor positioned to measure pressure in said dispense chamber; and
a pump controller comprising a processor and a tangible, non-transitory computer readable medium storing a set of instructions executable to cause the controller to:
operate the feed pump to reduce a volume of said feed chamber at a first predetermined rate while the isolation valve is open and the barrier valve is closed;
open the barrier valve to allow a fluid in the feed chamber to enter said dispense chamber while keeping said outlet valve closed so that none of the fluid entering the dispense chamber is dispensed;
take a first pressure measurement of the fluid in the dispense chamber using the pressure sensor;
determine whether the first pressure measurement is greater than a predetermined pressure;
in response to the first pressure measurement being greater than said predetermined pressure, operate the dispense pump to increase a volume of the dispense chamber at a second predetermined rate;
take a second pressure measurement of the fluid in the dispense chamber using the pressure sensor, wherein the second pressure measurement is taken while the dispense pump is operating to increase the volume of the dispense chamber;
determine whether the second pressure measurement is greater than the predetermined pressure;
in response to determining that the second pressure measurement is greater than the predetermined pressure, operate the feed pump at a decreased speed;
in response to determining that the second pressure measurement is not equal to or greater than the predetermined pressure, operate the feed pump at an increased speed;
determine whether the operation of the dispense pump has caused the volume of the dispense chamber to reach a predetermined volume;
in response to determining that the volume of the dispense chamber has not reached the predetermined volume, repeating the method from the step of measuring the second pressure; and
in response to determining that the volume of the dispense chamber has reached the predetermined volume, stopping the operation of the feed pump and the dispense pump.
8. The multiple stage pump of claim 7 , wherein the fluid has a viscosity of less than 5 centipoise.
9. The multiple stage pump of claim 7 , wherein:
the pump controller is further operable to:
close the barrier valve after the dispense chamber has reached the predetermined volume;
open the outlet valve; and
operate the dispense pump to dispense fluid from the multiple stage pump.
10. The multiple stage pump of claim 7 , wherein the first motor is a stepper motor.
11. The method of claim 10 , wherein the second motor is a permanent-magnet synchronous motor.
12. A computer program product comprising a tangible, non-transitory computer readable medium storing instructions executable to perform a method of controlling a multiple stage pump, the method comprising:
operating a feed pump to reduce a volume of a feed chamber at a first predetermined rate;
opening a barrier valve to allow a fluid in the feed chamber to enter a dispense chamber while keeping an outlet valve closed so that none of the fluid entering the dispense chamber is dispensed;
taking a first pressure measurement of the fluid in the dispense chamber using a pressure sensor disposed to measure pressure in the dispense chamber;
determining whether the first pressure measurement is greater than a predetermined pressure;
in response to the first pressure measurement being greater than said predetermined pressure, operating a dispense pump to increase a volume of the dispense chamber at a second predetermined rate;
taking a second pressure measurement of the fluid in the dispense chamber using the pressure sensor, wherein the second pressure measurement is taken while the dispense pump is operating to increase the volume of the dispense chamber;
determining whether the second pressure measurement is greater than the predetermined pressure;
in response to determining that the second pressure measurement is greater than the predetermined pressure, operating the feed pump at a decreased speed;
in response to determining that the second pressure measurement is not equal to or greater than the predetermined pressure, operating the feed pump at an increased speed;
determining whether the operation of the dispense pump has caused the volume of the dispense chamber to reach a predetermined volume;
in response to determining that the volume of the dispense chamber has not reached the predetermined volume, repeating the method from the step of measuring the second pressure; and
in response to determining that the volume of the dispense chamber has reached the predetermined volume, stopping the operation of the feed pump and the dispense pump.
13. The computer program product of claim 12 , wherein the method further comprises:
closing the barrier valve;
opening the outlet valve; and
operating the dispense pump to dispense fluid onto a wafer.
14. The computer program product of claim 12 , wherein operating the feed pump comprises operating a stepper motor.
15. The computer program product claim 14 , wherein operating the dispense pump comprises operating a permanent-magnet synchronous motor.
16. A method for controlling fluid pressure in a multiple stage pump comprising:
operating a feed pump to reduce a volume of a feed chamber at a first predetermined rate;
opening a barrier valve to allow a fluid in the feed chamber to enter a dispense chamber while keeping an outlet valve closed so that none of the fluid entering the dispense chamber is dispensed;
taking a first pressure measurement of the fluid in the dispense chamber using a pressure sensor disposed to measure pressure in the dispense chamber;
determining whether the first pressure measurement is greater than a predetermined pressure;
in response to the first pressure measurement being greater than said predetermined pressure, operating a dispense pump to increase a volume of the dispense chamber at a second predetermined rate;
taking a second pressure measurement of the fluid in the dispense chamber using the pressure sensor, wherein the second pressure measurement is taken while the dispense pump is operating to increase the volume of the dispense chamber;
determining whether the second pressure measurement is greater than a first threshold above the predetermined pressure or less than a second threshold below the predetermined pressure;
in response to determining that the second pressure measurement is greater than the first threshold, operating the feed pump at a decreased speed;
in response to determining that the second pressure measurement is less than the second threshold, operating the feed pump at an increased speed;
determining whether the operation of the dispense pump has caused the volume of the dispense chamber to reach a predetermined volume;
in response to determining that the volume of the dispense chamber has not reached the predetermined volume, repeating the method from the step of measuring the second pressure; and
in response to determining that the volume of the dispense chamber has reached the predetermined volume, stopping the operation of the feed pump and the dispense pump.
17. The method of claim 16 , wherein the fluid has a viscosity of less than 5 centipoise.
18. The method of claim 16 , further comprising;
closing the barrier valve;
opening the outlet valve; and
operating the dispense pump to dispense fluid onto a wafer.
19. The method of claim 16 , wherein operating the feed pump comprises operating a stepper motor.
20. The method of claim 19 , wherein operating the dispense pump comprises operating a permanent-magnet synchronous motor.
21. The method of claim 16 , further comprising filtering the fluid through a filter between the feed pump and the dispense pump.
22. A multiple stage pump comprising:
a feed pump comprising:
a feed chamber;
a first diaphragm movable in the feed chamber;
a first lead screw to move the first diaphragm;
a first motor coupled to the first lead screw to rotate the first lead screw;
a dispense pump fluidly coupled to the feed pump, the dispense pump comprising:
a dispense chamber;
a second diaphragm movable in the dispense chamber;
a second lead screw to move the second diaphragm;
a second motor coupled to the second lead screw to rotate the second lead screw;
a filter disposed in a fluid flow path between the feed pump and the dispense pump;
an inlet valve;
an isolation valve;
a barrier valve;
an outlet valve;
a pressure sensor positioned to measure pressure in said dispense chamber; and
a pump controller comprising a processor and a tangible, non-transitory computer readable medium storing a set of instructions executable by the processor to cause the controller to:
operate the feed pump to reduce a volume of said feed chamber at a first predetermined rate while the isolation valve is open and the barrier valve is closed;
open the barrier valve to allow a fluid in the feed chamber to enter said dispense chamber while keeping said outlet valve closed so that none of the fluid entering the dispense chamber is dispensed;
take a first pressure measurement of the fluid in the dispense chamber using the pressure sensor;
determine whether the first pressure measurement is greater than a predetermined pressure;
in response to the first pressure measurement being greater than said predetermined pressure, operate the dispense pump to increase a volume of the dispense chamber at a second predetermined rate;
take a second pressure measurement of the fluid in the dispense chamber using the pressure sensor, wherein the second pressure measurement is taken while the dispense pump is operating to increase the volume of the dispense chamber;
determine whether the second pressure measurement is greater than a first threshold above the predetermined pressure or less than a second threshold below the predetermined pressure;
in response to determining that the second pressure measurement is greater than the first threshold, operating the feed pump at a decreased speed;
in response to determining that the second pressure measurement is less than the second threshold, operate the feed pump at an increased speed;
determine whether the operation of the dispense pump has caused the volume of the dispense chamber to reach a predetermined volume;
in response to determining that the volume of the dispense chamber has not reached the predetermined volume, repeating the method from the step of measuring the second pressure; and
in response to determining that the volume of the dispense chamber has reached the predetermined volume, stopping the operation of the feed pump and the dispense pump.
23. The multiple stage pump of claim 22 , wherein the fluid has a viscosity of less than 5 centipoise.
24. The multiple stage pump of claim 22 , wherein:
the pump controller is further operable to:
close the barrier valve after the dispense chamber has reached the predetermined volume;
open the outlet valve; and
operate the dispense pump to dispense fluid from the multiple stage pump.
25. The multiple stage pump of claim 22 , wherein the first motor is a stepper motor.
26. The method of claim 25 , wherein the second motor is a permanent-magnet synchronous motor.
27. A computer program product comprising a tangible, non-transitory computer readable medium storing instructions executable to perform a method of controlling a multiple stage pump, the method comprising:
operating a feed pump to reduce a volume of a feed chamber at a first predetermined rate;
opening a barrier valve to allow a fluid in the feed chamber to enter a dispense chamber while keeping an outlet valve closed so that none of the fluid entering the dispense chamber is dispensed;
taking a first pressure measurement of the fluid in the dispense chamber using a pressure sensor disposed to measure pressure in the dispense chamber;
determining whether the first pressure measurement is greater than a predetermined pressure;
in response to the first pressure measurement being greater than said predetermined pressure, operating a dispense pump to increase a volume of the dispense chamber at a second predetermined rate;
taking a second pressure measurement of the fluid in the dispense chamber using the pressure sensor, wherein the second pressure measurement is taken while the dispense pump is operating to increase the volume of the dispense chamber;
determining whether the second pressure measurement is greater than a first threshold above the predetermined pressure or less than a second threshold below the predetermined pressure;
in response to determining that the second pressure measurement is greater than the first threshold, operating the feed pump at a decreased speed;
in response to determining that the second pressure measurement is less than the second threshold, operating the feed pump at an increased speed;
determining whether the operation of the dispense pump has caused the volume of the dispense chamber to reach a predetermined volume;
in response to determining that the volume of the dispense chamber has not reached the predetermined volume, repeating the method from the step of measuring the second pressure; and
in response to determining that the volume of the dispense chamber has reached the predetermined volume, stopping the operation of the feed pump and the dispense pump.
28. The computer program product of claim 27 , wherein the method further comprises:
closing the barrier valve;
opening the outlet valve; and
operating the dispense pump to dispense fluid onto a wafer.
29. The computer program product of claim 27 , wherein operating the feed pump comprises operating a stepper motor.
30. The computer program product claim 29 , wherein operating the dispense pump comprises operating a permanent-magnet synchronous motor.