Plasma-enhanced CVD of TiN and Ti using low-pressure and high-density helicon plasma

Abstract

Titanium nitride (TiN) and titanium (Ti) were deposited using a low-pressure and high-density helicon plasma process with titanium tetrachloride (TiCl 4). This study aimed to clarify the characteristics of the TiN and Ti deposition processes and the properties of films. The rate-determining process of the TiN film-deposition reaction was changed with the TiCl 4 partial pressure. High-deposition rate and excellent bottom coverage was achieved by using high TiCl 4 partial pressure, but low film resistivity was not achieved simultaneously. By increasing the RF biased power, an improvement of the bottom coverage and the film resistivity was possible. The Ti film was deposited successfully by helicon plasma with a deposition rate of 4 nm min −1 and a film resistivity of 300 μΩ cm. It was found that synthesizing Ti films by plasma-enhanced chemical vapor deposition (CVD) required higher plasma density. The use of helicon plasma is promising for the deposition of TiN and Ti films. However, the deposited Ti film was an amorphous structure; this would be caused by impurities in this film (30 at% oxygen and 15 at% silicon). These impurities would be suspected to be induced by sputter etching of the quartz glass belljar used for the plasma generation chamber and by desorbing of H 2O on the chamber wall.