Ta-Si-N as a diffusion barrier between Cu and Si

The barrier properties of reactive sputtered Ta-Si-N films were investigated using X-ray diffraction and AES depth profiling with a focus on the effect of the N-2/Ar gas flow ration of the reactive sputter deposition process on the barrier properties of Ta-Si-N.Ta-Si-N fails at 900 degrees C when it is in contact with Cu, while Ta and TaN fail at 600 degrees C and 650 degrees C, respectively. The optimum N-2/Ar flow ratio in sputter deposition of Ta-Si-N is 15%. The Ta-Si-N barrier fails by migration of Cu through the Ta-Si-N layer to the Ta-Si-N/Si interface and reaction of Cu with Si to form copper silicide. The crystallization temperature of Ta-Si-N in the Cu/Ta-Si-N/Si sample is higher than 900 degrees C. Therefore, the failure of Ta-Si-N 900 degrees C is not directly related to the crystallization of Ta-Si-N. (C) 1998 Elsevier Science S.A. All rights reserved.