Internal stresses in Cr, Mo, Ta, and Pt films deposited by sputtering from a planar magnetron source

Abstract

Extensive investigations of the internal stresses, electrical resistivities, optical reflectances, and microstructures of metal and semiconductor films sputtered from cylindrical‐post magnetron sources have established the existence of a universal transition phenomenon for these properties that depends sensitively upon the pressure of the sputtering gas and its mass relative to that of the target material. At low working pressures the sputtered films generally have compressive stresses and near bulk‐like values of their resistivity and optical reflectance. Little change is observed as the working pressure is raised, until a transition pressure is reached at which rapid changes in the deposited film properties begin to occur. The transition pressures for the various elements increase in a regular way with their atomic masses. A preliminary study by one of the authors also indicated that the values of the transition pressures were sensitive to the geometry of the sputtering source, being lower for sources of planar configuration. The present study reports the occurrence of the same transition phenomenon for a number of metals sputtered from a rectangular planar magnetron sputtering cathode, confirming the indicated decrease in transition pressures and finding it to be most pronounced for the lighter elements, in accord with an atomic peening model adopted previously.