2 June 2000 Characterization of solvent-rich resist coating process
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This paper studies the characteristics of a solvent-rich coating process which has demonstrated its abilities to provide wider resist thickness range and better coating uniformity on square substrates. The coating recipe being studied consists three spin steps, spread spin (1st spin), snap spin (2nd spin), and dry spin (3rd spin). A two-level, six-factor fractional factorial design of experiment (the screening test) is conducted first to determine which process parameters the film thickness and coating uniformity is sensitive to. A response surface model is then built for those significant factors. The screening test found that 3rd spin speed and time do not affect film thickness significantly, but should not be ignored in controlling coating uniformity. On the other hand, both 1st and 2nd spin speed and time are important to film thickness as well as coating uniformity. This is contrary to traditional coating systems where spin time is typically not an important factor in determining coating thickness. The central composite design was used to obtain the response surface model (RSM). Analysis shows that the model is adequate to represent the characteristics of a solvent-rich coating system. The four major factors, i.e., 1st spin speed and time, and 2nd spin speed and time are the dominant independent variables in determining film thickness. The first-order interactions between these major factors are weak. It is interesting to notice that the response surface model for coating uniformity is very unreliable, represented by poor model fitting statistics and high p values for individual factors. This is possibly due to the exclusion of 3rd spin speed and time in the central composite design.
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Bo Zhou, Bo Zhou, Ed V. Denison, Ed V. Denison, } "Characterization of solvent-rich resist coating process", Proc. SPIE 3998, Metrology, Inspection, and Process Control for Microlithography XIV, (2 June 2000); doi: 10.1117/12.386528; https://doi.org/10.1117/12.386528


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