Abstract

A VG HB5 STEM has been modified at Kings College London to allow computer controlled contamination writing on thin Carbon substrates. This method has been used to fabricate Fresnel Zone plates which have outer zone widths in the range 40 to 100 nM, and an accuracy of 10 nM over 50 uM (1). These zone plates consist of 150 nM thick carbon zones on a 30 nM Carbon film - equivalent to 120 nM thick "free standing" zones. This thickness of Carbon is semitransparent to soft X-ray radiation, and transmission (through zones which would ideally be opaque) results in a loss of focusing efficiency of the ZP. Whilst these ZPs have proved effective as high resolution soft X-ray focusing elements (2), it is desirable to replicate these structures in a material such as Gold for a number of reasons; (a) Replicating the Carbon patterns in the same thickness of gold can improve the ZP focusing efficiency and considerably extend its working wavelength range.

© 1986 Optical Society of America