Abstract
Thermal mass flow controllers are used in the semiconductor manufacturing process. A thermal MFC has three main components: a thermal mass flow sensor, a laminar flow bypass, and a flow control valve. To obtain a flow rate and response characteristic of high accuracy and low variability, it is particularly necessary to improve the stability of the thermal mass flow sensor. In the development of a new thermal mass flow sensor, quality engineering techniques were applied to a series of processes: parameter design was applied during the development process, production parameter optimization was applied to reduce variability in the production process, and Mahalanobis-Taguchi methods were used to optimize zero stability inspection. Three results were obtained:（1） robust sensor characteristics relating mass flow to sensor output;（2）low-drift zero stability by optimization of production parameters; and（3）optimal inspection by MT methods, using quickly obtained data.
