Plasma and gas-phase characterization of a pulsed plasma-enhanced chemical vapor deposition system engineered for self-limiting growth of aluminum oxide thin films

Aluminum oxide thin films were fabricated by pulsed plasma-enhanced chemical vapor deposition (PECVD) with continuous delivery of both O2 and trimethyl aluminum (TMA). By appropriately controlling the gas phase environment, self-limiting growth kinetics are obtained. Diagnostic measurements of the plasma and gas-phase composition were performed using emission spectroscopy and mass spectrometry. Emission spectroscopy shows that the plasma achieves steady state within a couple of seconds. Addition of TMA to an O2/Ar plasma causes the O atom density to drop ∼ 50%, while emission peaks due to TMA decomposition products scale with TMA partial pressure. Mass spectrometry confirms that TMA is unreactive with O2. Upon plasma ignition TMA is immediately consumed, forming the combustion products CO, CO2, H2O, and H2. Self-limiting film growth is demonstrated at room temperature.