Patent ID: 8658516
Filing Date: 2014-02-25
Classification: B23K,H01L

Abstract:
1. A method of producing a silicon wafer, comprising: irradiating a first laser beam onto an inner portion of a silicon wafer located at a predetermined depth measured from a surface of the silicon wafer to form a gettering site within the wafer for capturing heavy metals; and irradiating a second laser beam onto a beam-concentration portion that is above the gettering site and extends from the surface of the silicon wafer only partway to the gettering site to melt the beam-concentration portion; wherein a wavelength of the first laser beam is in a range of about 600 nm to about 1200 nm, and a wavelength of the second laser beam is in a range of about 100 nm to about 500 nm; wherein the energy density of the first laser beam is in a range of about 1×10 wherein the predetermined depth of the inner portion at which the first laser beam is concentrated is in a range of about 1 μm to about 1000 μm measured from the surface of the silicon wafer.