This investigation reports the effect of rapid-thermal-annealing (RTA) on metallic barrier TiN against the interdiffusions of Ti and Si into barium strontium titanate (BST) in Pt/BST/Pt/TiN/Ti/Si capacitors. In the integration of BST capacitors, the thermal budget of the BST deposition would cause the inter-diffusions of Ti and Si from Ti adhesion layer and Si plug respectively. This event would degrade the BST capacitors. To address this issue, rapid-thermal-annealed TiN barriers were deposited between the bottom electrode Pt and adhesion layer Ti. Optimal RTA condition for TiN were found in this experiment. Excellent electrical characteristics of Pt/BST/Pt/TiN/Ti/Si capacitors, including high dielectric constant (εr = 320), low leakage current (1.5×10-8 A/cm2) under 0.1 MV/cm, and greater than 10 year lifetime under 1.6 MV/cm were obtained with Ar+O2 mixed ambient at a low substrate temperature (300 °C).