Highly oxidation-resistant TiN barrier layers for ferroelectric capacitors

The characteristics of TiN film; which is well suited for use as the barrier layer of ferroelectric capacitors, were investigated. It was found that high-density TiN is more resistive against oxidation than low-density one. It was also revealed that the [200]-oriented TiN had higher oxidation resistance than the [111]-oriented one. However, whereas a thick Pt bottom electrode was previously used to prevent barrier layer oxidation, we found that the Pt thickness can be reduced to less than half with high-density [200]-oriented TIN. TiN oxidation followed the linear-oxidation law (a reaction-limited process) in the initial stage of oxidation, and the oxidation rate was found to be inversely proportional to the density and proportional to the etching rate. The etching rate of the [200]-oriented TiN was lower than that of the [111]-oriented TiN, indicating that (100) was less reactive than (111). Consequently, the [200]-oriented TiN film exhibited high oxidation resistance.