THE APPLICATION OF RAPID THERMAL ANNEALING TO REDUCE LEAKAGE CURRENT OF TA2O5

Abstract

Tantalum pentoxide (Ta2O5) is a promising dielectric material for very high density DRAM. This project is focused on the study of defect states, leakage current, and capacitance properties of Low Pressure Chemical Vapour Deposited (LPMOCVD) Ta2O5 films on n+-Si and p+-Si alter annealing at high temperature range (700°C~900°C) in O2 and N2O by means of Zero Bias Thermally Stimulated Current (ZBTSC), SIMS, XTEM, I-V characterization, etc. Higher temperature annealed samples tend to be less leaky. However, RTA makes Ta2O5 crystallized causing the sample surface uneven, and the thicker interfacial SiOx lowers the capacitance. N2O is proved to be a stronger oxidizing ambient than O2 in our annealing temperature range. The defect states in Ta2O5 are probably related to aluminum electrode, Si diffusion from substrate into Ta2O5, grain boundary, and carbon or hydrogen contamination.