Mechanical stresses in aluminum and copper interconnect lines for 0.18 μm logic technologies

The mechanical stress state of conventional Al and damascene Cu lines of a 0.18 mu m logic technology flow have been determined using a novel X-Ray diffraction method that permits measurement of stress on an array of critical-dimension lines on the product die. The effect of high density plasma oxide deposition and the influence of low-K dielectrics on the stress state of the Al lines is described. The effect of materials properties and fabrication methodology on the stress state of damascene Cu lines is shown with measurement of mechanical stress and strain in passivated lines at room temperature and during annealing. The effect of underlayer on the damascene Cu stress state is also quantified.