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

Abstract

Aluminum oxide thin films were fabricated by pulsed plasma-enhanced chemical vapor deposition (PECVD) with continuous delivery of both O 2 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 O 2/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 O 2. Upon plasma ignition TMA is immediately consumed, forming the combustion products CO, CO 2, H 2O, and H 2. Self-limiting film growth is demonstrated at room temperature.