Low Energy Ion Beam Assisted Deposition of Low Resistivity Aluminum Using TMAA

Abstract

Thermal deposition and Ga+ ion beam assisted deposition of Al using TMAA have been studied. At temperatures between 95ºC and 105ºC, where thermal deposition is negligible, the introduction of a low energy Ga+ ion beam (8 to 10 keV) produces selective deposition. Ion beam seeding followed by ion beam irradiation during TMAA flow leads to consistent selectivity at this temperature range. The lowest resistivity of selectively deposited Al film is 7 µΩ-cm, only 2.5 times the bulk Al resistivity. The selective deposition rate is about 300Å/min. Depositions at higher temperature produced very low resistivity Al films, but with a decreasing selectivity ratio. X-ray diffraction showed that deposited Al films are polycrystalline, with very small FWHM.