We have been developing a resist loss measurement function which is based on quantified pattern top roughness. In
order to use practically the resist loss detection function, the PTR index must be calibrated to amount of resist loss.
Furthermore, the evaluation of different chemical formulation and different film thicknesses of the resist is also
required. In this study, we explore the calibration technique of resist loss detection. In order to convert measured PTR
index into amount of resist loss, a reference measurement to pattern height is required. Techniques that can measure
local pattern height are limited to off-line techniques such as AFM or cross-sectional SEM with current technology.
These techniques have a very long Turnaround Time (TAT), and also highly skilled engineer is required, it cannot be
used for in-line processing. Then, we examined the reasonable calibration method by short TAT. At first, the calibration
wafer with changed resist film thickness is exposed using an "open frame" condition. It is measured by an optical film
thickness metrology (FTM) tool and CD-SEM, a conversion factor is determined and converted PTR index of measured
target patterns into resist loss amount. The validity of converted resist loss amount by this method has been proven by
comparing to the resist height obtained by AFM and cross-sectional SEM images. The calibration technique using PTR
index of un-patterned resist allowed us to understand the relationship between un-patterned resist thickness and resist
surface roughness. We have demonstrated a simple and easy way to calibrate pattern resist loss using CD-SEM top-down