Characterization of mechanical damage on structural and electrical properties of silicon wafers

The effect of artificial mechanical damage in Czochralski silicon wafers was studied by measuring the structural and electrical characteristics of the wafers. A liquid honing method was used to induce mechanical damage and the damage grade was varied by controlling process parameters. Surface microroughness of the damaged sample was analyzed using an atomic force microscope (AFM). The wet oxidation/preferential etch method, photo-acoustic displacement (PAD) method and the minority carrier lifetime with a laser excitation/microwave reflection photoconductance decay technique were used to characterize the intensity of mechanical damage in silicon wafers. As the degree of mechanical damage increases, the density of oxygen induced stacking faults (OISF) is increased, while the depth of OISF generation is almost independent of damage grade. The minority carrier lifetime is inversely proportional to the mechanical damage grade, while the PAD values are proportionally increased. Other experimental results are discussed from a viewpoint of a structure-property relationship.