A method for forming a semiconductor structure includes providing a semiconductor substrate, forming a gate stack on the semiconductor substrate, forming a silicon-containing compound stressor adjacent the gate stack, implanting non-siliciding ions into the silicon-containing compound stressor to amorphize an upper portion of the silicon-containing compound stressor, forming a metal layer on the silicon-containing compound stressor while the upper portion of the SiGe stressor is amorphous, and annealing to react the metal layer with the silicon-containing compound stressor to form a silicide region. The silicon-containing compound stressor includes SiGe or SiC.