| 摘要 |
PROBLEM TO BE SOLVED: To provide a wafer processing method capable of suppressing a device on a surface of a silicon wafer from being damaged by transmitted light when forming a modified layer inside the wafer by irradiating the wafer with a pulse laser beam having the wavelength set within a range from 1300 nm to 1400 nm.SOLUTION: A wafer processing method comprises the steps of: setting a wavelength of a pulse laser beam having permeability to a wafer within a range from 1300 nm to 1400 nm; positioning a condensing point of the pulse laser beam at the inside of the wafer, irradiating the wafer with the pulse laser beam from a rear surface 11b of the wafer, and forming a modified layer 19 inside the wafer by relatively processing and feeding holding means and laser beam irradiation means; and applying external force to the wafer and dividing the wafer along division schedule lines using the modified layer as a division start point. In the modified layer forming step, a polarization plane 71 of the pulse laser beam is positioned in a direction orthogonal to a processing feed direction.SELECTED DRAWING: Figure 7 |
