The effect of Ta to Si ratio on magnetron sputtered Ta-Si-N thin films

The role of composition on the resistivity and thermal stability of reactiv ely sputtered Ta-Si-N films have been studied using x-ray diffraction, Ruth erford backscattering spectrometry, and sheet resistance measurement. Films with higher silicon to tantalum ratio were found to be more thermally stab le and have higher sheet resistance than films with lower Si to Ta ratio. W hile Ta0.28Si0.07N0.65 starts to crystallize at about 900 degrees C, for ex ample, Ta0.24Si0.10N0.66, and Ta0.24Si0.12N0.64 remained amorphous and ther mally stable for heat treatment up to 1100 degrees C. In-situ sheet resista nce measurement showed that the resistivity of the alloys varies with compo sition and decreases with temperature; films with higher Ta/Si ratio have l ower resistivity. The resistivity of the films, at 30 degrees C, was about 675 Omega-cm, 285 Omega-cm, and 135 Omega-cm and decreased to 61.5 Omega-cm , 22.5 Omega-cm, and 19.5 Omega-cm at 480 degrees C for Ta0.24Si0.12N0.64, Ta0.24Si0.10N0.66, and Ta0.28S0.07N0.651 in that order. Our results indicat e that the composition of Ta-Si-N films could be manipulated to obtain low resistivity films that could be used in device applications.