Comparative Studies of Atomic Layer Deposition and Plasma-Enhanced Atomic Layer Deposition Ta2O5 and the Effects on Electrical Properties of In situ Nitridation

Abstract

Ta2O5 and TaOxNy thin films were deposited by atomic layer deposition (ALD) from Ta(NMe2)5 (PDMAT) with water, oxygen plasma, and nitrogen added oxygen plasma. The film properties were comparatively investigated focusing on the electrical properties from metal oxide semiconductor capacitor structure with 10 nm Ta2O5 or TaOxNy. The results show that plasma-enhanced ALD (PE-ALD) Ta2O5 film has better electrical properties including lower interface state density and leakage current than thermal ALD. Moreover, PE-ALD TaOxNy shows the best properties, indicating the beneficial effects of in situ nitridation. Especially, time dependent dielectric breakdown was significantly improved up to 4000 times of thermal ALD Ta2O5. These results show that, intentional in situ nitrogen incorporation with good electrical properties was successfully achieved by PE-ALD using nitrogen–oxygen mixture.