晶圓測機與預防維護之成本效益模式研究

Abstract

控片在半導體產業界會影響到產品的品質及製程的穩定度，在機台與製程的控制上，以控片執行測機是作為機台進行生產之重要依據。針對控片之測機項目進行合理之篩選，將可使測機控片做有效之控制安排，也會影響生產時間，進而影響產出量，另外亦可提升良率。 本研究可分為機台測機方案選擇模式及成本效益模式兩部份，可以用來作為機器控制、預防維謢及製程管控的工具，此測機方案選擇模式及成本效益模式會受到機台的維修與故障狀況等因素之影響，而此狀況也會引起機台產能及產品品質之變化。機台測機方案選擇的形成，主要取決於產品的批次狀況及良率的大小，而在產品製造的過程中所產生的成本效益，是來自於產品的銷售金額與投資成本之間的預估，此預估值與機台每日測機時間(t1)、預防維謢時間(t2)、預防維謢間隔天數(d)及產品良率(y)有關係。 所發展出的測機方案選擇模式，主要目的在於提供較佳測機方案之選擇，節省控片之使用次數與數量，進而節省控片成本。而成本效益模式主要目的是藉由t1、t2、d及y的運算，得到總銷售金額與總投資成本，使總成本效益(Total Benefit，TB)最大，亦可獲得相關績效與效益。

Control wafer plays an important role in the semiconductor industry since it will affect the final product's quality and the stability of the manufacturing process. During the control process of machines and production line, the most important impact factor is how to implement the control wafer monitoring and testing procedures, and then affect the production rate, production volume and also enhance the production yield rate. In this research, we will study accurate and reasonable selection of control wafer's monitoring and testing items. In this study, there are two sections including the selection of wafer testing machine models and the evaluation of the cost/ benefit models to control, prevent, and maintain the testing machines, and hence control the production line. These two kind of models are affected by the machine's maintenance and breakdown conditions which will lead to the variation of machine capacity and product quality. The selecting procedure of wafer testing machines model is constructed by deciding the batch size and yield rate for the producing products, and the cost/ benefit on the production process is evaluated by the estimation of the sales volume of product and the investment cost. This estimation is related to machine's daily testing time (t1), preventive maintenance time (t2), preventive maintenance interval time (d), and the product's yield rate (y). On one hand, the purpose in this study is to develop a superior selecting wafer testing model. Using this model, the frequency and quantity of control wafers, and related cost can be reduced. On the other hand, the purpose of developing the cost/ benefit model for wafer monitor and preventive maintenance is to obtain the decision variables of t1, t2, d, y to maximize the total sales. The related performance and cost/ benefit are also obtained from this model.