A linear programming model for the control wafers downgrading problem

Shu Hsing Chung*, W.l. Pearn, He Yau Kang

*Corresponding author for this work

Research output: Contribution to journalArticle

3 Scopus citations


This paper considers the control wafers downgrading problem (CWDP) in the wafer fabrication photolithography area. The objective of the research is to minimize the total cost of control wafers, while maintaining the same level of production throughput. For the problem under a pulling control production environment, a linear programming model is presented to set the supply rate of new control wafers and the recycle and downgrading rates so as to minimize the total cost of control wafers. A numerical example is given to illustrate the practicality of the model. The sensitivity of the linear programming model solution to changes in the underlying parameter values is also investigated. The results demonstrate that the proposed model is an effective tool for determining the control wafers downgrading policy. This paper presents a linear programming model that considers the cost of new control wafers, recycle and downgrading control wafers in wafer fabrication. The proposed model improved the performance of control wafers management, and served as the basis for setting the usage rates of control wafers.

Original languageEnglish
Pages (from-to)377-384
Number of pages8
JournalInternational Journal of Advanced Manufacturing Technology
Issue number3-4
StatePublished - 1 Feb 2005


  • Control wafers
  • Downgrading
  • Linear programming model
  • Performance
  • Pull control

Fingerprint Dive into the research topics of 'A linear programming model for the control wafers downgrading problem'. Together they form a unique fingerprint.

  • Cite this