Surface nitridation of silicon dioxide with a high density nitrogen plasma

Abstract
A high density nitrogen plasma generated with a helicon plasma source has been used to incorporate approximately 15 at. % nitrogen into the top 0.5 nm of a silicon dioxide layer. The surface nitridation was accomplished in 10 s with a high flux of low energy ions which were extracted from the high density nitrogen plasma and accelerated in the plasma sheath towards the surface an electrically floating silicon dioxide surface. A rf compensated Langmuir probe was used to measure the nitrogen ion energy and ion current density as a function of the nitrogen pressure and source power. The nitrogen ion energy, ion current density, and exposure time determine the nitrogen range and dose into the silicon dioxide surface. This process may be advantageous for nitriding the gate oxide in advanced complementary metal–oxide semiconductor process flows.