Evaluating the reliability level of virtual metrology results for flexible process control: a novelty detection-based approach

Pilsung Kang, Dongil Kim, Sungzoon Cho

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


The purpose of virtual metrology (VM) in semiconductor manufacturing is to support process monitoring and quality control by predicting the metrological values of every wafer without an actual metrology process, based on process sensor data collected during the operation. Most VM-based quality control schemes assume that the VM predictions are always accurate, which in fact may not be true due to some unexpected variations that can occur during the process. In this paper, therefore, we propose a means of evaluating the reliability level of VM prediction results based on novelty detection techniques, which would allow flexible utilization of the VM results. Our models generate a high-reliability score for a wafer’s VM prediction only when its process sensor values are found to be consistent with those of the majority of wafers that are used in model building; otherwise, a low-reliability score is returned. Thus, process engineers can selectively utilize VM results based on their reliability level. Experimental results show that our reliability generation models are effective; the VM results for wafers with a high level of reliability were found to be much more accurate than those with a low level.

Original languageEnglish
Pages (from-to)863-881
Number of pages19
JournalPattern Analysis and Applications
Issue number4
StatePublished - 16 Oct 2014

Bibliographical note

Funding Information:
The first author was supported by the research program funded by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2011-0021893) and by the Ministry of Science, ICT, and Future Planning (NRF-2014R1A1A1004648). The dataset used in this paper can be available upon request.

Publisher Copyright:
© 2014, Springer-Verlag London.


  • Novelty detection
  • Process monitoring
  • Reliability level
  • Semiconductor
  • Virtual metrology


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