The objective of the project was to evaluate polysilicon CD etch bias as it was affected by etch time, measurement feature within the exposure field, and the product being measured. Characterization of the trends has generated a summarizing model that uses etch time, measurement feature, and product type as significant factors in determining polysilicon CD etch bias. Etch time was found to be a continuous factor, while measurement site and product type were categorical. Measurement Site A was found to be independent of measurement Site B, independent of Site C, etc., as well as Product 1 was found independent of Product 2. When tested with JMP Statistical software the generated model produced an R-sq Adj. =0.96. A comparison of modeled values with collected data for several different combinations of conditions showed a maximum difference of 6% on a normalized scale.
Munson, Jasper P.
"Analysis and Modeling of Polysilicon Critical Dimensions,"
Journal of the Microelectronic Engineering Conference: Vol. 13
, Article 22.
Available at: http://scholarworks.rit.edu/ritamec/vol13/iss1/22