The effects of metallization thickness on the thermal and long-term stability of Pd/Sn Ohmic contacts have been investigated. Metallization samples are furnace annealed at various temperatures and systematically characterized utilizing Scanning Electron Microscopy (SEM) and current-voltage (I-V) measurements. Contact resistivities, rho(c), of the metallizations are measured using a conventional Transmission Line Model (cTLM) method. SEM is utilized to investigate the surface morphology of the contacts, Thermal stability analysis of the metallizations is carried out at 410 degrees C for 10 h, whereas long-term stability tests are performed at 300 degrees C for 400 h. After annealing at 410 degrees C for 10 h, rho(c) of the Pd(30 nm)/Sn(150 nm) metallization remains in the high 10(-5) Omega cm(2) range, whereas for the Pd(30 nm)/Sn(90 nm) and Pd(40 nm)/Sn(120 nm) contacts rho(c) values increase to the mid 10(-4) Omega cm(2) range under the same annealing conditions. The Pd(30 nm)/Sn(150 nm) metallization also displays improved long-term stability at 300 degrees C when compared to the Pd(30 nm)/ Sn(90 nm) and Pd(40 nm)/Sn(120 nm) contacts. The effects of a highly conductive overlayer; Au, on the thermal and long-term stability of Pd/Sn Ohmic contacts are also investigated.