晶圓製造廠日生產管制模式之構建

Abstract

半導體晶圓製造為目前國內最具競爭力的產業之一，然而由於晶圓製造複 雜的製程特性，以及存在於生產環境中種種的變異，使得本產業在生產管 理上相當地困難。現今國內晶圓製造業者普遍面臨產品生產週期時間過長 ，週期變異程度過大，以及系統在製品量過高等問題，更突顯了維持合理 的在製品水準，以及選取適當之投料法則、派工策略的重要性。吾人基於 生產線平衡、在製品量控制的理念，以及滿足規劃需求的考量，來進行晶 圓製造的現場排程與控制。由於在晶圓的製造過程中，需要一再地經過黃 光機台的加工，所以吾人以黃光步驟將整個製程予以分段，每一段視為一 個迴圈（layer）。本研究首先以金屬濺鍍將晶圓製程區分為前後兩段， 並分析製程前後段的生產特性，以進行各個迴圈生產目標值的規劃。在後 段的部分，透過實際產出量與計劃產出量的差值來訂定生產目標，主要目 的是希望滿足規劃之需求。在前段的部分則透過部分TG & MA演算法的運 作，並配合後段製程的需求拉動，以達成生產線平衡來制定日生產目標。 在決定了整個系統之生產目標後，還要再配合一套適當的投料法則及派工 策略，以確實達成日規劃目標。經由模擬的驗證, 透過本日生產管制模組 的運作，系統確實能提高規劃產出的達成率並維持不錯的生產線平衡。 The complex process and high variation in wafer fabrication make its production management very difficult. Problems, such as long cycle time, high cycle-time variations, and high level of WIP (work in process) are not unusual in this industry. It reveals the importance in maintaining a reasonable WIP level to shorten cycle time by developing a suitable policy for wafer releasing and dispatching.Line balancing, WIP control, and planned target achievement are the major concern of this research to develop a model for wafer releasing and dispatching. This research first analyzes the process of wafer fabrication and divide it into two sections according to production characteristics(the last sputtering operation step). In the back-end section, the objective of planning focuses on achieving the planned output so that the production target is set according to the difference between the actual output andthe planned output. In the front- end section, daily production target is determined by using a portion of TG&MA[Chang et al. 1992] algorithm. Its major focus is to satisfy the pull demand of the back-end section to balance the line. In order to meet the decided production target, the model should be cooperated by a suitable policy of wafer releasing and lot dispatching. Simulation results from a real world example show that the proposed daily production model indeed increase the percentage of achievement ofplanned output while maintaining a balanced line.