Giuseppe Fazio & Massimo Strada, ST Microelectronics, Central R&D, Agrate Brianza, Italy

ABSTRACT

In the modern fab process control is very important. The process control may be improved by modifications to equipment. The wafer-cleaning process is one of the most important and critical steps in semiconductor manufacturing. In this process two or more chemicals are mixed and it is very important to have the correct concentrations. Repeatability and reproducibility in concentration impact on the process quality. The chemical input usually is guaranteed by mechanical flow controllers installed in every chemical line, where a narrowing regulated by a valve provides the correct flows entering the DIW line. The performance of such flow controllers is affected by several variables: chemical pressure or DIW flow, which could generate fluctuations during the chemical injection phase.