EFFECT OF INTERPOSED CR LAYER ON THE THERMAL-STABILITY OF CU TA/SI STRUCTURE/

The thermal stability of Cu/Ta/Cr/Si structure is analyzed and compare d with that of Cu/Ta/Si and Cu/Ta/Cr/Ta/Si structures. The Cu/Ta/Si an d Cu/Ta/Cr/Ta/Si systems retained their structures up to 600 degrees C without increase in resistivity but the Cu/Ta/Cr/Si structure was deg raded after annealing at 400 degrees C. In the latter case, the degrad ation was dominated by the outdiffusion of free Si, probably released from the substrate in the formation of CrSi2. It is suggested that the released Si is reactive and its outdiffusion through Ta layer is faci litated by the high affinity of Si toward Ta, as expected from the lar ge negative value of mixing enthalpy between Ta and Si. (C) 1996 Ameri can Institute of Physics.