Calibration of a Microlithographic Fabrication Process Using Non-Destructive Testing and Rigorous Electromagnetic Theory

Comparison of rigorous electromagnetic calculations and measurements of grating diffraction efficiencies are applied to estimate the profile of surface relief gratings. The depth of the gratings is estimated using a Linnik interferometer. Information regarding the grating duty cycle (filling factor) and edge slope can then be extracted. The inverse scatter process is inexpensive, non-destructive, and easy to carry out and its accuracy is estimated. The rcsults are applied to calibrate a manufacturing process involving writing with a laser-beam-writing system and etching using reactive ion etching. It is shown that a combination of TE and TM polarisation measurements and calculations can be used to extract a great deal of accurate metrological information.