Simulation-Based Evaluation of Lot Release Policies in a Power Semiconductor Facility – a Case Study

Abstract

Lot release policies, i.e., the decision which lots to start in production, in what quantity and at what time, have a significant influence on fab performance. Recent research focused on closed-loop policies. However, most studies only demonstrated the feasibility in settings with low-mix or low-volume simulation testbeds. In this paper, we focus on a real-world pre-assembly facility in a high-volume and high-mix semiconductor wafer fab. We conduct an in-depth, deterministic discrete-event simulation in two stages, using real production data and demands. First, we test two existing open-loop lot release policies (random and constant release) against a simple closed-loop release policy. Significant improvements in on-time delivery, bottleneck utilization, and throughput are notable. Second, we compare three closed-loop release policies and indicate which policy provides the best results for certain KPIs like enhanced on-time delivery or reduced tardiness.

Automated and Optimized Lot-To-Order Matching in 300 mm Semiconductor Facilities

“…Thus, slight over-deliveries might occur, which are balanced within the supply chain. We conducted a simulation study to develop approaches for optimal and uniform lot-to-order matching and start date allocation, considering the current product mix, tool equipment, and setup times [11]. The released batches and splits are now evenly distributed.…”

“…However, each adjustment or add-on results in increasing complexity for programming and maintenance. Therefore, we tested a more dynamic, mathematical approach and conducted a discrete event simulation study that showed promising results [11]. Although the current LTOM process is stable and highly automated, IFD seeks to replace the RTD rules with a mathematical solver if the complexity increases.…”

Bir Üretim İşletmesinde Simülasyon Yöntemi ile Darboğaz Analizi ve Sistem İyileştirmesi

“…AnyLogic yazılımını kullanan bir diğer çalışmada [17] bir hassas imalat firmasının otomatik depolama ve boşaltma sistemlerine yatırım yapması durumunda çıktı performansının ne düzeyde olacağını, etmen tabanlı modelleme ve kesikli olay simülasyonunun birlikte kullanarak modellemişlerdir. Başka bir çalışmada ise, [18] bir yarıiletken plaka üretim fabrikasının ön montaj sürecini, mevcut durumda uygulanan üretim partilerini serbest bırakma politikalarını analiz etmek ve süreci iyileştirmek amacıyla ele almışlardır. Çalışmalarında gerçek süreç verilerine dayalı olarak geliştirdikleri simülasyon modeli ile mevcut durumu analiz etmişler, kaynak kullanım oranı, çıktı miktarı ve zamanında teslimat oranında önemli iyileştirmeler sağlayan öneriler ortaya koymuşlardır.…”

Streamlining Semiconductor Manufacturing of 200 mm and 300 mm Wafers: A Longitudinal Case Study on the Lot-to-Order-Matching Process

“…EMICONDUCTOR manufacturing is a complex and costsensitive process characterized by sophisticated devices with short life cycles, fast-changing product mixes, and reentrant product flows comprising hundreds of processing steps on complex and expensive equipment [1]- [3]. The manufacturing process is twofold.…”

“…In contrast, organizations that follow the Morethan-Moore strategy seek diversification through a broader product mix. However, this approach requires high flexibility and efficient processes, as the simultaneous handling of numerous different products with varying customer due dates is challenging [1], [8]. With the highly complex production planning and control, allocating supply and demand is both a strategic and operational decision [9].…”