MICRO: Taking Control

A control system attached to a PVD tool can be used to customize recipes during process development, perform process monitoring to detect misprocessed wafers, and optimize PM cycles. he increasing demand for fewer defects, higher throughput, and cost reductions in semiconductor processing has sparked steady interest in advanced process control (APC). Many companies are evaluating APC's potential to increase capacity while investing little capital. This article focuses on how a major Asian semiconductor foundry increased its process understanding of a physical vapor deposition (PVD) tool. The study involved a control package on a PVD tool that was equipped with six sensors. This setup enabled company engineers to characterize previously unknown details of the process and prevented wafer misprocessing through active fault detection. The heart of the APC system in this installation was the FabGuard control package from Inficon (East Syracuse, NY). FabGuard collects data from integral as well as add-on sensors and analyzes the data using advanced statistical and modeling techniques. By comparing an active process with a model developed from previous runs, the system can detect excursions from acceptable processing, detecting faults with minimal false alarms. At the fab where this study was conducted, the control package was installed on an Endura 5500 from Applied Materials (Santa Clara, CA) through the tool's secondary SECS port. The tool was equipped with two aluminum-silicon-copper metal deposition chambers, a preclean chamber, and two degas chambers. Each of these chambers had active residual gas analysis (RGA) sensors, and the preclean chamber also had a particle monitor. After performing a series of wafer runs to characterize the system, the engineers had a picture of the process, which they could compare with process improvements and which they could use as a baseline to detect process excursions. To provide a baseline for controlling the PVD process, the