Wafer dividing method

A method of dividing a wafer which is partitioned by a plurality of first dividing lines extending in a predetermined direction and a plurality of second dividing lines formed in a predetermined direction perpendicular to the plurality of first dividing lines, forming intersections of the first dividing lines and the second dividing lines, comprising the steps of:

• storing coordinate values of intersections between the first dividing lines and the second dividing lines;
• forming a first deteriorated layer inside of the wafer along the first dividing lines continuously between neighboring intersections by continuously applying a laser beam of a wavelength capable of passing through the wafer except at the intersections based on the stored coordinate values of the intersections;
• forming a second deteriorated layer inside of the wafer along the second dividing lines continuously between neighboring intersections by continuously applying a laser beam of a wavelength capable of passing through the wafer except at the intersections based on the stored coordinate values of the intersections;
• dividing the wafer along the first dividing lines where the first deteriorated layer has been formed or the second dividing lines where the second deteriorated layer has been formed by exerting external force to the wafer along the first dividing lines or the second dividing lines after the first deteriorated layer forming step and the second deteriorated layer forming step;
• and
• dividing the wafer along the second dividing lines where the second deteriorated layer has been formed or the first dividing lines where the first deteriorated layer has been formed by exerting external force to the wafer along the second dividing lines or the first dividing lines after the first dividing step.