Some give examples from manufacturing, and others from research and development. They cover engineering areas such as chemical vapor deposition, furnace and implant, metallization, etch, and photolithography. They deal with topics such as process optimization, equipment reliability, detection of drift and warm-up effects, sampling plan reduction, tracking the progress of wafer lots through a device development laboratory, preventive maintenance plans, selection of bunny suits for use in clean rooms, use of cheaper recycled wafers instead of virgin wafers, and wafer planarization. Most case studies are straightforward applications of statistics that require little formal training, while some require a broader knowledge of statistics to fully understand the material. These engineering objectives are reached most efficiently by using statistical methods.
Statistical methods are an integral part of the structured approach of the qualification plan.
They provide a framework for thinking about an engineering problem and a vocabulary that helps engineers communicate their results across different engineering areas. The case studies in the book illustrate applications of these statistical methods. Optimize process and verify stability. Improve reliability and demonstrate manufacturability. Part 6 is a comprehensive case study.