Paper
25 March 2008 Dimensionality reduction methods in virtual metrology
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Abstract
The objective of this work is the creation of predictive models that can forecast the electrical or physical parameters of wafers using data collected from the relevant processing tools. In this way, direct measurements from the wafer can be minimized or eliminated altogether, hence the term "virtual" metrology. Challenges include the selection of the appropriate process step to monitor, the pre-treatment of the raw data, and the deployment of a Virtual Metrology Model (VMM) that can track a manufacturing process as it ages. A key step in any VM application is dimensionality reduction, i.e. ensuring that the proper subset of predictors is included in the model. In this paper, a software tool developed with MATLAB is demonstrated for interactive data prescreening and selection. This is combined with a variety of automated statistical techniques. These include step-wise regression and genetic selection in conjunction with linear modeling such as Principal Component Regression (PCR) and Partial Least Squares (PLS). Modeling results based on industrial datasets are used to demonstrate the effectiveness of these methods.
© (2008) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Dekong Zeng, Yajing Tan, and Costas J. Spanos "Dimensionality reduction methods in virtual metrology", Proc. SPIE 6922, Metrology, Inspection, and Process Control for Microlithography XXII, 692238 (25 March 2008); https://doi.org/10.1117/12.772739
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CITATIONS
Cited by 4 scholarly publications.
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KEYWORDS
Data modeling

Semiconducting wafers

Metrology

Feature selection

Principal component analysis

Plasma etching

Neural networks

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