Investigation of Nitrided Atomic-Layer-Deposited Oxides in 4H-SiC Capacitors and MOSFETs

Abstract

MOSFETs and capacitors have been fabricated to investigate the atomic layer depositon (ALD) of SiO2 onto SiC compared to thermal oxidation of SiC. Devices were fabricated on 4H-SiC with the following oxidation treatments: thermal oxidation at 1175°C, thermal oxidation at 1175°C followed by a nitric oxide (NO) anneal at 1175°C, and ALD of SiC at 150°C followed by an NO post oxidation anneal (POA) at 1175°C. ALD of the SiO2 was performed using 3-aminopropyltriethoxysiliane (3-APTES), ozone and water. Capacitors fabricated with NO annealed ALD oxide and thermal oxide with NO POA exhibited similar CV behavior and yielded similar Dit of 1e11 at 0.5 eV from the conduction band. MOSFETs fabricated with NO PDA ALD oxide exhibited peak field effect mobilities ranging from 32 – 40.5 cm2/Vs compared to 30 –34.5 cm2/Vs for the MOSFETs with NO annealed thermal oxide. The higher mobilities exhibited by the ALD gate oxides were linked through SIMS to higher nitrogen concentrations at the SiO2/SiC interface.