Automation: Key to cycle time improvement in semiconductor manufacturing

摘要

“Cycle Time Drives Everything”. The commitment of product delivery on time is paramount in any industry. It is particularly important in the brutal fast paced semi-conductor manufacturing industry due to tremendous competition in the market. Up until the manufacturing of 200mm wafers, cycle time was largely dependent on the “human” factor. With the advent of 300mm wafers, along with increasing market and customer needs it is hard to imagine semiconductor manufacturing without Factory Automation. In this paper, automation refers to direct equipment control, automated material transportation, and realtime lot dispatching. The paper focuses on implementation of automation on diffusion batch furnaces. Major work was done from the Equipment Interface (EI) perspective along with Real Time Dispatch (RTD) and the furnace software integration. Although the paper focuses on automation based on Tokyo Electron Ltd. (TEL) batch process manufacturing platform, the same logic can be applied to other batch process manufacturing systems. All batch processes as the name suggests process multiple wafers at the same time. A single batch consists of multiple types of wafers namely product wafers, monitor wafers and extra/side dummies (also referred to as fillers) each with a specific function in forming a batch. It is important how these wafers are delivered to the process tools and managed pre/post processing while maintaining safety, efficiency and productivity of the batch tool. An optimized strategy for batch preparation and dispatch showed overall 30% reduction in total dispatch time. A major part of these changes revolved around the filler wafer management which can be sub-divided based on filler wafer process counts and their thickness accumulation. Wait time improvement of 20% is seen on the tool set which use counts based filler wafers while, tool sets which use thickness accumulation based filler wafers showed 25% improvement in wait time.