High Precision Dispense System
Precisely controlled dispensing of photoresist is one of the key process steps in photolithography. Besides basic requirements like a bubble-free dispense, the accuracy and flow rate profile influence the uniformity of a coating. Up to date, high precision dispensing was an exclusive domain of positive displacement pump systems. SUSS MicroTec recently introduced a pressure-based dispense system, which breaks into this area. A dispensed volume repeatability of ± 1 % (3 σ) and accuracy of ± 2 % was made possible by means of sophisticated monitoring and control mechanisms. Furthermore, a flow-sensor located at the latest possible point allows for monitoring the real flow and controlling the system accordingly. Software algorithms act as the backbone of system performance. The system can be used to dispense chemicals with viscosities from 1 cps to 10,000 cps.