Effect of NH3 flow on electrical and mechanical properties of ALD TiN thin films

Abstract

ALD TiN thin films with good electrical and mechanical properties are required for applications in nano-scale devices, especially DRAM capacitor electrodes. In this paper, it is confirmed that the TiN electrical and mechanical properties have strong relationships with the NH3 flow during the deposition. It is shown that the deposition condition with higher NH3 flow induces both the TiN(111) preferred crystal orientation and Cl impurity reduction. This indicates that higher NH3 partial pressure during the TiN deposition not only enhances the close-packed TiN(111) crystal growth, which theoretically has higher planar density, but also break Ti-Cl bonding more efficiently. Consequently, the ALD TiN electrical/mechanical properties of resistivity, hardness and modulus value were improved by approximately 20%, 75% and 40%, respectively with increasing NH3 flow rate from 500 sccm to 4,000 sccm.