Plasma Enhanced Atomic Layer Deposition of Tantalum Nitrides Thin Film using Hydrogen Radical As a Reducing Agent

摘要

Plasma enhanced atomic layer deposition (PEALD) of tantalum nitrides (Ta-N) thin films at a temperature of 260°C using terbutylimidotris(diethylamido)tantalum (TBTDET) and hydrogen radicals is described. Alternate surface reaction between TBTDET and hydrogen radicals, which was served as a reducing agent, yielded superior films with an electric resistivity of 400 μΩ-cm and no aging effect under the exposure to air. The film thickness per cycle is saturated at 0.8 A/cycle with sufficient pulse time of TBTDET. X-ray diffraction analysis indicates that the as-deposited films are not amorphous but polycrystalline with cubic Ta-N. The film density is increased as the pulse time and the power of hydrogen plasma increases. The Ta-N films are Ta-rich in composition, and contain around 15 at.% of carbon impurity. The carbon element in the film is identified as bonded to Ta by X-ray photoelectron spectroscopy (XPS). It clearly demonstrates the perfect step coverage of PEALD even on the 0.3μm diam hole with slightly negative slope and 10:1 aspect ratio.