US Patent 7642113 Semiconductor wafer dividing method

An element is formed on the major surface of a semiconductor wafer, and a groove is formed in the back surface of the semiconductor wafer along a dicing line or chip dividing line by a mechanical or chemical method. A modified layer is formed by irradiating the groove with a laser, and the semiconductor wafer is divided by using the modified layer as a starting point. The back surface of the semiconductor wafer is removed to at least the depth of the groove.