Patent ID: 8703582

Claim:
A method for laser processing, comprising the steps of: forming a front-side modified region inside of an element-group formation substrate having a plurality of electronic elements formed on a front surface of a plate-shaped substrate in one direction along a surface of the substrate by irradiating the element-group formation substrate sequentially with a laser beam having a predetermined output from a back surface side of the substrate in the one direction, and collecting the laser beam sequentially to a part inside of the substrate which part has a predetermined depth from the back surface; and forming a back-side modified region inside of the substrate along the front-side modified region by irradiating the element-group formation substrate sequentially with a laser beam having one other output smaller than the predetermined output from the back surface side of the substrate in the one direction along the surface of the substrate, the element-group formation substrate having the front-side modified region formed therein, and collecting the laser beam sequentially to a part inside of the substrate which part has one other depth from the back surface shallower than the predetermined depth.