Closed loop control over delivery of liquid material to semiconductor processing tool

Abstract

Liquid material is precisely dispensed to a semiconductor processing tool utilizing closed loop control. In one embodiment, CMP slurry material of known density is supplied from a reservoir/mixing vessel to a dispense module. The dispense module also receives a flow of an inert gas through a gas supply valve. Positive pressure arising within the dispense module due to the inert gas flow causes an outflow of slurry from the dispense module to the CMP platen. The rate of flow of the slurry to the CMP platen over time is determined by monitoring the change (decline) in weight of the filled dispense module. In a similar manner, variation in the rate of flow of slurry over time may be detected by monitoring variation in changes in weight of the filled dispense module over time. A regulator structure in electronic communication with the dispense module and with the gas supply valve receives first signals at different time points indicating the weight change of the dispense module. In response, the regulator structure communicates a second signal to the gas supply valve, reflecting an appropriate change in the rate of flow of CMP slurry material to the platen. This second signal causes the gas supply valve to vary the flow of inert gas to the dispense module in order to control changes in the flow rate of the slurry.