Nanoelectrode lithography is a pattern duplication method which combine template and electrochemical reaction. With the nanoelectrode lithography, electrochemical reaction occurs along with the conductive area of the template, and oxide pattern can be directly fabricated on a surface of semiconductor or metal layer. This "Resist-less patterning" method may have advantage for precise patterning in the future.

Highly accurate X-ray masks are strongly required to establish SR lithography technology. X-ray masks must be produced as accurately as the LSI devices, because a one-toone projection aligner system is used. To minimize the in-plane mask distortion, it is desirable to estimate the value of the stress and the non-uniformity in the membrane fabrication (SiN) process. The values of the stress were estimated from the measurement of the warpage and the calculation. It is very difficult to obtain the stress distribution in the SiN/Si wafer. Thus, we measured the minority carrier lifetime distribution using the non-contact laser/microwave method. The carrier injection was done by a 774nm or 904nm semiconductor laser diode, and their beam was focused to about 500 μmφ. The surface lifetime, τ s, of the SiN/Si wafer with the stress over ˜ 108dyn/cm2 decreased to 60–70% of that of the bare Si wafer. Thus, the contactless laser/microwave system can be adaptable for the characterization in the X-ray mask process.

This paper discusses the properties of materials for x-ray masks used in synchrotron radiation lithography system. Through computer simulations and experimental analysis, we evaluate three kinds of membranes (Si, SiN, SiC) in terms of mechanical distortions, surface smoothness and optical transmittance. SiC exhibits the smallest distortion, but SiN has the best characteristics in the surface smoothness and the optical transmittance. By virtue of their high x-ray absorption coefficient and dry etching capabilities, Ta, W and Re are selected as potential absorber materials. We study their stress control characteristics, etching characteristics and the relation between their Young's modulus and distortions. We find that Ta is an excellent absorber because of its good stress controllability and good etching characteristics, such as a high etch rate and etch selectivity. By adopting a Ta/SiN structure, highly accurate masks can be fabricated by a process in which patterning the absorber is carried out before removing the bulk Si.