Principles and techniques of STM lithography

Abstract

Conventional electron beam lithography suffers from limitations set by source brightness, lens aberrations and space charge effects. The scanning tunneling microscope is an entirely new configuration that avoids these limits and so offers the possibility of higher throughput and greater choice of patterning processes. Here we review early experiments aimed at demonstrating these advantages and to determine the practicality of this form of patterning. Both conventional resist exposure and resistless processes were demonstrated and showed sub-100nm resolution and pattern transfer was also demonstrated. Achieving high throughput appears to be very challenging because the small separation (>100nm) needed for adequate resolution makes high speed scanning impractical. One possible way around this problem is to micromachine arrays of STM tips so that the exposure can be carried out in parallel.