@article{(Open Science Index):https://publications.waset.org/pdf/418,
	  title     = {A CUSUM Control Chart to Monitor Wafer Quality},
	  author    = {Sheng-Shu Cheng and  Fong-Jung Yu},
	  country	= {},
	  institution	= {},
	  abstract     = {C-control chart assumes that process nonconformities follow a Poisson distribution. In actuality, however, this Poisson distribution does not always occur. A process control for semiconductor based on a Poisson distribution always underestimates the true average amount of nonconformities and the process variance. Quality is described more accurately if a compound Poisson process is used for process control at this time. A cumulative sum (CUSUM) control chart is much better than a C control chart when a small shift will be detected. This study calculates one-sided CUSUM ARLs using a Markov chain approach to construct a CUSUM control chart with an underlying Poisson-Gamma compound distribution for the failure mechanism. Moreover, an actual data set from a wafer plant is used to demonstrate the operation of the proposed model. The results show that a CUSUM control chart realizes significantly better performance than EWMA.
},
	    journal   = {International Journal of Industrial and Manufacturing Engineering},
	  volume    = {7},
	  number    = {6},
	  year      = {2013},
	  pages     = {1183 - 1188},
	  ee        = {https://publications.waset.org/pdf/418},
	  url   	= {https://publications.waset.org/vol/78},
	  bibsource = {https://publications.waset.org/},
	  issn  	= {eISSN: 1307-6892},
	  publisher = {World Academy of Science, Engineering and Technology},
	  index 	= {Open Science Index 78, 2013},
	}