Effect of TiN treated by rapid thermal annealing on properties of BST capacitors prepared by RF magnetron co-sputter system at low substrate temperature

Abstract

In this work, (Ba0.7Sr0.3)TiO3 thin films on Pt/TiN/Ti/Si substrate were deposited by an RF magnetron co-sputter system at 300 degrees C in an Ar+O-2 mixed ambient. In the integration of BST capacitors, the diffusion barrier (TiN) under bottom electrodes is one of the key issues. To obtain a stable and excellent diffusion barrier against inter-diffusion between Pt and Si, as well as against being oxidized during BST deposition, TiN was treated by a rapid thermal annealing (RTA) process. Experimental results indicated that proper RTA treatments resulted in a superior TiN barrier layer. In addition, low substrate temperature during BST deposition suppressed the phenomena of inter-diffusion and barrier oxidation. Furthermore, Pt hillocking, another problem during BST deposition because of high thermal budget, was also solved by reducing substrate temperature during BST deposition. The MIM (Pt/BST/Pt) structure was used in the experiments for electrical properties measurement. High dielectric constant (epsilon (r)=300), low leakage current (1.5x10(-8) A/cm(2)) under 0.1MV/cm, and 10 year lifetime under 1.6MV/cm were achieved with an Ar+O-2 mixed ambient at a low substrate temperature (300 degrees C).