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A method and system for dispensing a precise amount of a chemical used in the fabrication of semiconductors utilizes rolling membrane pump and calculates an amount by which to change a dispense based at least in part on a predicted membrane flex. Membrane flex is predicted, at least in part, by the

A method and system for dispensing a precise amount of a chemical used in the fabrication of semiconductors utilizes rolling membrane pump and calculates an amount by which to change a dispense based at least in part on a predicted membrane flex. Membrane flex is predicted, at least in part, by the shape of the membrane, a volume of liquid to be dispensed and a pressure during dispense.

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1. An apparatus for dispensing chemicals used in semiconductor fabrication processes, comprising: a reservoir for storing a supply of a chemical used in fabrication of semiconductors; a dispense point from which the chemical is dispensed; a pump in fluid communication with the reservoir for

1. An apparatus for dispensing chemicals used in semiconductor fabrication processes, comprising: a reservoir for storing a supply of a chemical used in fabrication of semiconductors; a dispense point from which the chemical is dispensed; a pump in fluid communication with the reservoir for pumping a desired volume of the chemical out of the dispense point, the pump including, a piston reciprocating within a pumping chamber and displacing a known volume based on a distance that it is displaced, the movement of the piston causing displacement of chemical from a pumping chamber to the dispense point; a diaphragm partially supported by the piston and extending between the piston and sides of the pumping chamber, the diaphragm having associated with it deformation during at least a portion of a pumping cycle, the deformation resulting in displacement from the pumping chamber of a lesser volume of chemical than the volume displaced by the piston; and a controller mechanism for moving the piston to dispense the chemical through the dispense point, the controller mechanism accounting for predicted deformation of the diaphragm during dispensing in order to pump the desired volume of the chemical. 2. The apparatus of claim 1, further including a pressure sensor in communication with the pumping chamber for generating an indication of pressure of the chemical within the pumping chamber, wherein the deformation of the diaphragmn is caused, at least in part, on pressure of chemical within the pumping chamber acting against the diaphragm during displacement of the piston, and wherein controller mechanism moves the piston to account for the predicted deformation of the diaphragm based in part on the indication of pressure.3. The apparatus of claim 2, wherein the indication of pressure is taken during a first dispense of chemical, and the predicted deformation of the diaphragm during a subsequent dispense is based at least in part of the indication of pressure from the first dispense.4. The apparatus of claim 3, wherein the indication of pressure taken during the first dispense includes a maximum pressure sensed during the first dispense.5. The apparatus of claim 2, wherein a velocity of movement of the piston during a dispense is adjusted in response to the indication of pressure during the dispense.6. The apparatus of claim 1, wherein the deformation of the diaphragm is based at least in part on the desired volume of the chemical to be pumped out of the dispense point.7. The apparatus of claim 1, further including a pressure sensor adopted for generating an indication of pressure, wherein the controller mechanism monitors the indication of pressure during displacement of the piston for a sudden pressure drop indicating a failure.8. The apparatus of claim 1, further including a linearly reciprocating mechamcal actuator releasably coupled to the piston.9. The apparatus of claim 1, further including a linearly reciprocating mechanical actuator releasably coupled to the piston by a removable collar.10. The apparatus of claim 1, wherein the controller mechanism includes: a linearly reciprocating mechanical actuator releasably joined to the piston by a collar, the collar having a removable portion that, when in place, couples the piston and actuator and, when removed, permits relative movement of the piston and actuator for disconnecting the mechanical actuator from the piston. 11. A method for dispensing a precise amount of a viscous liquid utilizing a pump with a piston partially supporting a diaphragm extending between the piston and sides of a pumping chamber, said method comprising: determining an adjustment to a distance to move the piston to account for increased volume in the pumping chamber caused by deformation of the diaphragm during dispensing, the amount of the adjustment based at least in part on a predicted deformation of the diaphragm during dispensing; opening an output valve of said pumping system for p ermitting the viscous liquid to be dispensed; and moving the piston the adjusted distance in order to displace from the pumping chamber the desired volume of viscous liquid to a dispense point, whereupon the viscous liquid is dispensed. 12. The method of claim 11, further including monitoring a pressure of the liquid in the pumping chamber during dispensing.13. The method of claim 12 wherein said monitoring of the pressure includes monitoring for a sudden decrease in said pump chamber pressure and stopping dispensing.14. The method of claim 12, further comprising automatically adjusting a velocity of movement of said piston in response to the pressure of the liquid in the pumping chamber during dispensing.15. The method of claim 14, wherein automatically adjusting comprises: increasing the velocity of movement of the piston until the pressure of the liquid in the pumping chamber reaches said predetermined maximum pressure; and decreasing the velocity of movement of the piston if the pressure is higher than a predetermined high pressure suitable for operation of said pumping system. 16. The method of claim 11, wherein the predicted diaphragm deformation is based at least in part on the desired volume of the viscous liquid to be dispensed during movement of the piston.17. The method of claim 11, wherein the predicted diaphragm deformation is based at least in part on a pressure of the liquid within the pumping chamber measured during a prior dispense.18. The method of claim 17, wherein the pressure of the liquid within the pumping chamber is a maximum of pressure of the liquid during the prior dispense.19. A method for dispensing a precise amount of a viscous liquid utilizing a pump with a piston partially supporting a diaphragm extending between the piston and sides of a pumping chamber, said method comprising: determining an adjustment to a distance to move the piston to account for increased volume in the pumping chamber caused by deformation of the diaphragm during dispensing, the amount of the adjustment based at least in part on a desired volume of the viscous liquid to be dispensed during movement of the piston; opening an output valve of said pumping system for permitting the viscous liquid to be dispensed; moving the piston the adjusted distance in order to displace from the pumping chamber the desired volume of viscous liquid to a dispense point, thereby dispensing the viscous liquid; and monitoring pressure of the viscous liquid in the pumping chamber. 20. The method of claim 19, wherein ihe predicted diaphragm deformation is based at least in part on a pressure of the liquid within the pumping chamber measured during a prior dispense.21. The method of claim 20, wherein the pressure of the liquid within the pumping chamber is a maximum of pressure of the liquid during the prior dispense.22. The method of claim 19 wherein the monitoring of the pressure includes monitoring for a sudden decrease in said pump chamber pressure and stopping dispensing.23. The method of claim 19, further comprising automatically adjusting a velocity of movement of said piston in response to the pressure of the liquid in the pumping chamber during dispensing.24. The method of claim 23, wherein automatically adjusting comprises: increasing the velocity of movement of the piston until the pressure of the liquid in the pumping chamber reaches said predetermined maximum pressure; and decreasing the velocity of movement of the piston if the pressure is higher than a predetermined high pressure suitable for operation of said pumping system.