Chamber and Recipe-Independent FDC Indicator in High-Mix Semiconductor Manufacturing

This paper describes a chamber and recipe-independent fault detection and classification (FDC) indicator using the example of aluminum sputtering tools. We developed this indicator to detect abnormal discharge in an aluminum sputtering chamber when using a legacy FDC system. Abnormal discharge has several modes in the sputtering chamber, with abnormal discharge to a wafer commonly causing pattern defects. The indicator has been improved to detect only this problem, and to minimize the impact of false alarms that cause a loss of equipment productivity. The indicator can be readily extended to new chambers and the control limits are easily set for all recipes. This is because the equation for the indicator is very simple, and both the equation and the control limits are common to all sputtering chambers and recipes. It can therefore significantly reduce the setup work required of engineers, which is one of the biggest challenges in high-mix semiconductor manufacturing. The indicator is easily applied to newly installed tools at start of production and restrains the number of scrap wafers at minimum level. We also describe the mechanism of trace data changes in abnormal discharge modes using equivalent electrical circuits.