Susumu Iida

TL;DR: In this paper, a projection electron microscopy (PEM) system was employed to achieve the required inspection sensitivity applicable for 1X nm node, which enabled us to do inspection in higher resolution and with higher speed.

Abstract: High-sensitivity extreme ultraviolet (EUV) mask pattern defect detection is one of the major issues remaining to be addressed in device fabrication using extreme ultraviolet lithography. In order to achieve inspection sensitivity and suitability for the 1× nm node, a projection electron microscope (PEM) system is employed that enables high-speed/high-resolution inspection, which is not possible using conventional deep ultraviolet or electron beam inspection systems. By employing higher electron energy in the electron optics (EO) exposure system and by improving the PEM design, we have minimized the aberration that occurs when working with EO systems and we have improved the transmittance of the system. Experimental results showing the improved transmittance were obtained by making electron throughput measurements. To guarantee the tool’s aptness for 16-nm node EUV mask inspection, corresponding sized programmed defects on masks were designed, and the defect detection sensitivity of the EO system was evaluated. Improvements in image resolution and electron throughput have enabled us to detect 16-nm sized defects. The PEM system was integrated into a pattern inspection system for defect detection sensitivity evaluation.

TL;DR: In this article, the authors investigated the impact of electron scattering in extreme ultraviolet reflective multilayer (ML) on electron image and found that the secondary electron emission coefficient of Ru capped ML was lower than that of Ru bulk layer when the incident electron energy was more than 0.5

TL;DR: In this paper, the authors used simulated projection electron microscope (PEM) images to detect 16-nm size defects on an hp 64-nm patterned EUV mask and showed that the optimization of current density and image processing techniques were essential for the detection of defects.

TL;DR: In this paper, the authors used Monte Carlo simulation to identify the residual-type defect on the extreme ultraviolet (EUV) mask and the secondary electron image. And they found that the surface potential of the residual type defects on the EUV mask greatly affected the mirror electron image, which suggests that the thickness of residual type defect is identi cable.