晶圓批量異常等待時間為導向之派工法則

Abstract

在顧客至上的理念下，滿足顧客之交期已成為晶圓廠首要之目的，但由於製造現場常會發生當機，使得生產週期時間產生劇烈變化，進而影響產品交期，故生產週期時間的控制已成為製造現場最重要的課題。 「派工」，為製造現場動態控制生產週期時間的方法，一般常用之派工，如CR，僅將生產週期分成兩部分：純加工時間與等待時間，來作為選擇加工優序之依據。但生產週期時間會發生變異，主要是因製造現場發生當機而使批量發生異常等待所致，故本研究進一步將生產週期時間解構成三部分：純加工時間、正常等待時間與當機所造成之異常等待時間，並且以異常等待時間作為選擇加工優序之依據，依據模擬結果顯示，以異常等待時間為導向之派工法則績效明顯優於其他派工法則。

This research develops several dispatching rules for IC foundries in order to improve the on-time delivery. On-time delivery is a key performance indicator in an IC foundry. Yet, it cannot be well controlled due to the occurrence of unexpected events such as machine down. This research decomposes the cycle time into three parts: processing time, expected waiting time, and unexpected waiting time. The expected waiting time concerns the waiting of lots in the case of no unexpected events. The unexpected waiting is concerned with the waiting of lots caused by unexpected events. In this research, each lot is given a time buffer to accommodate the unexpected events. The basic idea is that lots with less remaining time buffer is more urgent and has higher dispatching priority. Several dispatching indicators based on this idea has been developed and tested by simulation. Simulation results using 10 seeds show that one of the proposed dispatching rules, MCR (modified Critical Ratio), in average is better than other dispatching methods in literature.