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Engineering Statistics Handbook Episode 5 Part 2

Tham khảo tài liệu 'engineering statistics handbook episode 5 part 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 3.5.1.1 Background and Data ENGINEERING STATISTICS HANDBOOK home TOOLS Ỉ AIDS IS-EARCH back next 3. Production Process Characterization 3.5. Case Studies 3.5.1. Furnace Case Study 3.5.1.1. Background and Data Introduction In a semiconductor manufacturing process flow we have a step whereby we grow an oxide film on the silicon wafer using a furnace. In this step a cassette of wafers is placed in a quartz boat and the boats are placed in the furnace. The furnace can hold four boats. A gas flow is created in the furnace and it is brought up to temperature and held there for a specified period of time which corresponds to the desired oxide thickness . This study was conducted to determine if the process was stable and to characterize sources of variation so that a process control strategy could be developed. Goal The goal of this study is to determine if this process is capable of consistently growing oxide films with a thickness of 560 Angstroms - 100 Angstroms. An additional goal is to determine important sources of variation for use in the development of a process control strategy. Process Model In the picture below we are modeling this process with one output film thickness that is influenced by four controlled factors gas flow pressure temperature and time and two uncontrolled factors run and zone . The four controlled factors are part of our recipe and will remain constant throughout this study. We know that there is run-to-run variation that is due to many different factors input material variation variation in consumables etc. . We also know that the different zones in the furnace have an effect. A zone is a region of the furnace tube that holds one boat. There are four zones in these tubes. The zones in the middle of the tube grow oxide a little bit differently from the ones on the ends. In fact there are temperature offsets in the recipe to help minimize this problem. http www.itl.nist.gov div898 handbook ppc section5 ppc511.htm 1 of 7 5 1 2006 10 18 01 AM .