Reduction of Carbon Impurities in Aluminum Nitride from Time-Resolved Chemical Vapor Deposition Using Trimethylaluminum

Aluminum nitride (AlN) is a semiconductor with a wide range of applications from light-emitting diodes to high-frequency transistors. Electronic grade AlN is routinely deposited at 1000 degrees C by chemical vapor deposition (CVD) using trimethylaluminum (TMA) and NH3, while low-temperature CVD routes to high-quality AlN are scarce and suffer from high levels of carbon impurities in the film. We report on an atomic layer deposition-like CVD approach with time-resolved precursor supply where readsorption of methyl groups from the AlN surface is suppressed by the addition of an extra pulse, H-2, N-2, or Ar, between the TMA and NH3 pulses. The suppressed readsorption allowed deposition of AlN films with a carbon content of 1 at. % at 480 degrees C. Kinetic and quantum-chemical modeling suggests that the extra pulse between TMA and NH3 prevents readsorption of desorbing methyl groups terminating the AlN surface after the TMA pulse.Funding Agencies|Swedish Foundation for Strategic Research (SSF) through the project "time-resolved low temperature CVD for III-nitrides" [SSF-RMA 15-0018]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty grant SFO Mat LiU) [2009 00971]; Swedish Research Council (VR)Swedish Research Council