Focused Ion Beam Fabrication of Graded Channel Field Effect Transistors (FETs) in GaAs and Si

摘要

The aim of our focused ion beam research program at M.I.T. is to exploit the unique capabilities of this novel technology in fabricating devices which have a lateral gradient of doping. (This program of research will be continued so that this final report will be exhaustive.) Using internal institute funds, M.I.T. purchased a focused ion beam system capable of producing beams of the common dopants of Si and GaAs (i.e., B, Si, and Be) at energies up to 300 keV. In order to carry out the proposed implantations the system needed to be upgraded in several ways. Pattern writing software was developed, as well as software for translating patterns written in MAGIC, a layout system in use at M.I.T., into the FIB format. To achieve the minimum beam diameter the ion column had to be realigned mechanically and electrical noise needed to be reduced in the circuits which deflect the beam. With the upgraded system we have written patterns in PMMA with 50 nm line width, and achieved metal lift-off of 50 nm width lines. (RH)