Electrical characterization of multilayer masks for extreme ultraviolet lithography

Abstract

Articles you may be interested inEvaluation of extreme-ultraviolet lithography mask absorber pattern on multilayer phase defect using extremeultraviolet microscope Voltage potentials on the surface of a mask blank form one of the mechanisms by which errors in mask patterning may be introduced. When electrical currents flow through the mask either from the patterning beam or induced through other means, it is the impedance to ground from the point being patterned on the mask that determines the potential developed. Ten multilayer coated mask blanks from four sources were provided by Sematech for electrical characterization. The initial purpose of this project is to experimentally determine the resistance between various points in the quality area to likely ground locations on the mask. The mask can be grounded on the top, side or bottom edges. Initial attempts to characterize the resistance with a variety of measurement tools proved to be inconsistent. A test fixture was then assembled to enable voltage-current ͑V-I͒ characteristic measurements to be made on the samples. Several key issues were observed. First, the behavior was not very stable-the V-I characteristics were observed to transition between several different resistance modes. Second, quite a few of the modes observed exhibited semiconductor-like behavior. We have included representative examples of the results. Details of the experimental setup and the results obtained from the samples are presented and the behavior is explained.

Fringe field theory and experiment for electrostatic chucking of extreme ultraviolet photomasks

“…6 All of the following results that follow are for the first set ͑continuously coated͒ unless stated otherwise. However, this was difficult to confirm with experiments as proper grounding of the top multilayer stack was difficult due to the diodelike behavior of the Mo-Si multilayer.…”