Applying statistics to find the causes of variability in aluminum evaporation: a case study

A study of the causes of variability in the thickness of aluminum deposited on silicon wafers is presented. A work team was assembled to define and characterize the process, equipment, and measuring techniques adequate to the available means. The most important variables were studied, and, through a variance analysis, the ones that contribute the most to the variability were selected. The relationship among the vital variables was established using the Taguchi technique. A test run was performed and the C_PK showed an increase, effectively reducing the variability