Forward Echelon-based Inventory Monitoring in Semiconductor Supply Chain
Date Issued
2007
Date
2007
Author(s)
Lin, Hon-Wen
DOI
zh-TW
Abstract
The semiconductor industry with its high capital investment and hi-tech nature faces fierce competition and quick environment changes. Furthermore, semiconductor manufacturing system is a very complicated multistage production process, transferring silicon in a form of polished disk into integrated circuits. Especially in wafer fabrication, it is time-consuming and complicated one, consisting of six major types of process: Diffusion, Lithography, CVD, Thin Film, Etching and Ion Implantation. With the characters of re-entrant production operations, high capital investment and hi-tech nature and vertical disintegration, each member of supply chain has different might and pursues for different goals. Therefore, this results in the poor performance of supply chain and the difficulty in monitoring it. In order to enhance the service levels and improve the performance of the whole supply chain, it is essential for the front-end member to lead all members to share their information and synchronize their operations, i.e., there is a need to integrate the front-end and back-end in the semiconductor supply chain to meet customers’ on-time delivery requirement and service level.
This research develops concept of forward echelon-based inventory and uses CONWIP system to develop a semiconductor supply chain monitoring scheme. The first step in the proposed scheme is to construct a forward echelon-based two-echelon model which takes the features of the production system into consideration with the goal of minimizing the echelon WIP inventory control limits of the supply chain under the service level constraints. Next, the model is solved iteratively through raising the service level of the internal echelon. The algorithm searches the proper internal service level with the concept of binary search. With the resulting echelon WIP inventory control limits from the model, the proposed monitoring scheme has been validated through simulation study.
Based on the simulation validation results, the conclusions are drawn as follows:
(1) By raising the service levels of internal echelon, the proposed scheme can effectively derive WIP inventory limits of two echelons, which is lower than the stage-based WIP inventory limits;
(2) Compared to the traditional stage-based inventory monitoring scheme, the proposed forward echelon-based monitoring scheme can obtain a higher service level under the lower inventory levels. This is the result of allocation of the WIP limits and the utilizing of overall information.
Subjects
半導體供應鏈
層級在製存貨
CONWIP
Semiconductor Supply Chain
Echelon WIP Inventory
Type
thesis
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