Initial Processes of Atomic Layer Deposition of Al(2)O(3) on InGaAs: Interface Formation Mechanisms and Impact on Metal-Insulator-Semiconductor Device Performance

Interface-formation processes in atomic layer deposition (ALD) of Al(2)O(3) on InGaAs surfaces were investigated using on-line Auger electron spectroscopy. Al(2)O(3) ALD was carried out by repeating a cycle of Al(CH(3))(3) (trimethylaluminum, TMA) adsorption and oxidation by H(2)O. The first two ALD cycles increased the Al KLL signal, whereas they did not increase the O KLL signal. Al(2)O(3) bulk-film growth started from the third cycle. These observations indicated that the Al(2)O(3)/InGaAs interface was formed by reduction of the surface oxides with TMA. In order to investigate the effect of surface-oxide reduction on metal-insulator-semiconductor (MIS) properties, capacitors and field-effect transistors (FETs) were fabricated by changing the TMA dosage during the interface formation stage. The frequency dispersion of the capacitance-voltage characteristics was reduced by employing a high TMA dosage. The high TMA dosage, however, induced fixed negative charges at the MIS interface and degraded channel mobility.