PARTICLE CONTAMINATION IN LOW-PRESSURE ORGANOMETALLIC CHEMICAL-VAPOR-DEPOSITION REACTORS - METHODS OF PARTICLE-DETECTION AND CAUSES OF PARTICLE FORMATION USING A LIQUID ALANE (ALH3) PRECURSOR

Two methods of analyzing particles were interfaced to a low pressure c hemical vapor deposition reactor used to deposit Al films from the liq uid precursor dimethylethylamine alane. A laser light scattering parti cle counter was used to monitor particles ( > 200 nm) in real time and established that the appearance of particles corresponded to the flow of precursor into the reactor. A particle impaction system was used t o collect particles ( > 20 nm) for analysis using analytical transmiss ion electron microscopy and electron diffraction. Typical sizes of the Al particles were in the range 20-1000 nm. Purposely introducing trac e amounts of H2O, CO, and O2 into the reactor during the flow of the p recursor caused an increase in the number of particles. Our results su ggested that Al particle formation was induced by impurities in the ga s phase (particularly H2O) although competing mechanisms could not be ruled out.