晶圓製造廠新製程導入階段產能分配模式之構建(I)

Abstract

當新製程開始上線量產時，因為生產知識不足，良率偏低且不穩定，管理者僅分配 部分產能做新製程生產。當新製程生產的良率達到某一水準且穩定的狀態後，全部產能 皆由新製程生產。從新製程開始上線量產至全部產能皆由新製程生產的期間稱之為 production ramp-up。在新製程的 ramp-up階段，顧客訂單仍須依賴良率穩定的舊製程生 產，因此在ramp-up階段是由新、舊製程共用產能。為了快速將產線轉成新製程生產，而 大量的投新製程的料片，學習各型機台最適參數(recipe)，此時因新製程的生產知識不 足，製程良率偏低且不穩定，產出大量的不良品，造成浪費、客戶訂單無法準時交貨及 客戶流失的窘境。反之，若為滿足客戶需求，而大量的投舊製程的料片，因新製程的投 料片較少，生產線上的學習較緩，將延誤新製程導入的時機，失去市場競增優勢。生管 人員在ramp-up 的各時段，在新、舊製程的良率、產出、成本、產能及客戶訂單的考量 下，很難決定如何分配產能給新、舊製程。目前業界僅靠生管人員的直接判斷，欠缺一 套分析管理機制協助他們分析決策的良莠。如何訂定ramp-up的各時段新、舊製程最適產 能分配，及新製程批量中急批的數量，以達成降低成本、增加收益、在ramp-up結束時 新製程的良率可達到給定的水準，及滿足ramp-up階段客戶需求的目標是一重要的議 題。本計畫之目的為協助晶圓製造廠，構建新製程導入階段，新舊製程產能分配決策模 式及評估產能分配的績效。

For providing a competitive selling price, semiconductor manufactures continuously improve their production process to reduce manufacturing cost. For rapid product lifecycle and expensive development cost, a new production process is frequently introduced to the production line when its production process knowledge is ill understood. During this time, the yield of the new production process is very low and unstable. The rate of ramp-up is influenced by yield learning of new production process. Yield in ramp-up stage is generally learned by two factors. One is learning by doing, the other is learning by experimentation. These two factors are generally determined by the numbers of release new production process lots. Should we release a large number of new production process lots to learn production process knowledge for shortening ramp-up time, or should we keep major part of capacity for current production process for meeting customer demands? During the ramp-up period how to allocate capacity to meet the target yield level at the end of ramp-up stage and customer demands is an important issue in wafer fabrication plant. In this study we will develop a capacity allocation model for current and new production process during ramp-up stage to maximum profit.