Stress and Plastic Flow in Silicon During Amorphization by Ion-Bombardment

The stress in silicon wafers during ion-bombardment was determined by wafer curvature measurements using an in-situ laser-scanning technique. Measurements were made as a function of ion species (noble gases and Si) energy (1-3 MeV), fluence, flux, and sample temperature (100-400K). In a typical experiment, compressive stress was built-up in the bombarded region as a function of fluence, until a continuous buried amorphous layer was formed. The magnitude of the compressive stress (20-100 MPs) depended strongly on the flux. During further amorphization by continued bombardment, the stress decreased and eventually stabilized.