Dave Wehrs & Chuck Gould, NT International & Huaping Wang, Entegris, Inc.

ABSTRACT

The accurate control of liquid flow is critical for attaining high process yields in wet etch, CMP delivery, and on-demand chemical blending applications. To maintain high purity, a flow control technology must minimize particle addition to the fluid stream. This article will present laboratory data to demonstrate the low levels of particle generation associated with the use of a differential pressure (DP)-based flow controller. The flow controller performs closed-loop control using direct flow and pressure measurement, and is used for in-situ monitoring and control of a process liquid flow rate. Differential pressure flow measurement technology allows this device to measure liquid flow rate without the use of moving parts. The flow controller’s valve technology provides control with low particle addition to the fluid stream during actuation. The valve seat and diaphragm are designed to minimize dead volume and fluid shear, reducing the possibility of process contamination. Also, to avoid excessive movement, the valve diaphragm actuation stroke is minimized. Testing was completed under three different conditions that represent probable-use cases of the device. Test results indicate low levels of particle generation during flushing and normal operation of the device confirming that semiconductor equipment users can use the flow controller for high-purity applications sensitive to particle generation. This provides users with another tool
for managing materials integrity.