Comparative studies of atomic layer deposition and plasma-enhanced atomic layer deposition Ta₂O₅ and the effects on electrical properties of In situ nitridation

Ta₂O₅ and TaO_xN_y thin films were deposited by atomic layer deposition (ALD) from Ta(NMe₂) ₅ (FDMAT) 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 TaO_xN_y. 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 TaO_xN_y 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.