晶圓製造廠考量製程規格能力與垂直鎖定機台限制下主生產排程修正機制

Abstract

隨著半導體製程技術的演進，積體電路之設計趨勢朝向微小化。為了因應新製程技術的提升與對準精度上的要求，使得晶圓製造必須於符合其製程規格能力的機台上加工，才能滿足日益嚴謹的製程要求，是故形成了微影與蝕刻作業中製程規格能力與垂直鎖定機台的限制，尤其是在微影與蝕刻工作站內，機台功能性強弱不均之現象，使得產品於通過兩工作站時生產週期時間造成相當的變異。 本文首先發展出兩混合整數規劃模式，在降低生產週期時間變異的前提下進行產能分配，據以估算出於此先進製程下微影與蝕刻兩工作站內各機台利用率，並進而針對同一工作站各機群具利用率差異之情境，發展一估算各產品生產週期時間之方法。此外，本文之「產能利用率最大差異設定模組」，則是控制一機群利用率最大差異值，目的在避免微影與蝕刻工作站內的機群利用率與工作站平均利用率差異過大，導致通過微影與蝕刻工作站之產品生產週期時間產生大幅變異，喪失各產品之生產週期時間競爭力。於此模組中，更針對整體利用率不足，及生產週期時間過長兩種不同情境，發展出生產計劃調整模式來調整主生產排程之產出目標。最後，「投料規劃模組」旨在兩工作站內機群利用率具有差異之情境下，以均勻微影工作站各機群內之機台負荷水準為主要概念，制訂投料計劃、設定現場在製品量與發展派工法則。依此流程，可產生一考量製程規格能力與垂直鎖定機台下之主生產排程規劃結果。 驗證結果顯示，考量機群利用率差異下區段基礎式週期時間估算法，所估算各產品之生產週期時間與模擬相比，最大誤差約在8%，平均誤差約在5%，而「產能利用率最大差異設定模組」，之生產計劃調整模式，能夠快速調整出合理之主生產排程計劃，而「投料規劃模組」之設計，使得現場之生產運作除能達到預定產出目標外，微影與蝕刻工作站內各機台亦能維持所規劃之產能利用率。整體而言，本文所發展之模式，可以作為考量製程規格能力與垂直鎖定機台下主生產排程計劃制訂之參考依據。

As the semiconductor process technology progress, the inevitable trend of IC product developing is toward mini-size. Hence, in order to meet new manufacturing technology and the precise alignment, wafers must be processed on the machines that satisfy process specification. As a result, the process window and machine dedication restrictions have appeared within photo and etching workstation. The different machines capabilities will probably affect the variance of product cycle time. In this thesis, we first develop two mix-integer programming model to allocate capacity loading between machine groups of photo and etching workstation for minimizing the variability of product cycle time. Then, the utilization rate of each machine group within photo and etching workstations is derived. Next, we also develop a cycle time estimation methodology to estimate the cycle time of each product considering different utilization rates of machine groups existed in photo and etching. Furthermore, in the controlling maximum utilization difference module, a value is set as the maximum utilization difference between machine groups for photo and etching workstations to avoid the product cycle time being lengthened due to the too large machine utilization and hence lose industry competitiveness. In this module, we also develop production plan adjustment models for the too low average utilization rate and the too long product cycle time scenarios to revise the production target. Finally, we proposed a material release planning module to balance the machine groups utilization within a workstations by setting a fixed a release sequence,adopting CONWIP release rule and developing dispatching rule. Following the above procedure, a reasonable master production schedule under the constraint of process window and machine dedication is obtained. Experiment reveals that comparison the cycle time, estimated by the block based cycle time estimation methodology under various utilization, with that of simulation result, the maximum error is within 8% and the average error is about 5%. Besides, by controlling of maximum utilization difference, production plan adjusting models can generate suitable MPS quickly. Also, based on the material release planning module, the utilization rate of photo and etching workstations can be maintained at planned level and the system production performance can be achieved. Consequently, the mechanism proposed in this thesis can be used as reference for master production planning under the constraint of process window and machine dedication.