METHOD FOR FORMING A SERIES OF DEFECTS AT DIFFERENT DEPTHS IN A SHEET OF MATERIAL, SHEET OF MATERIAL AND ELECTRONIC DEVICE

There is described a method of forming defects inside a sheet of material by using a laser system. The material has a damage irradiance threshold and an optical transparency window. The method has the steps of: moving a focal spot of a pulsed laser beam relatively to said sheet such that said focal spot moves in back and forth sequences across a thickness of said sheet as the focal spot is moved along a plane of said sheet, while emitting laser pulses of said pulsed laser beam, said laser pulses having a wavelength within said optical transparency window and having an irradiance at said focal spot exceeding said damage irradiance threshold thereby forming a plurality of defects inside said sheet, the plurality of defects being distributed both along said plane and across said thickness of said sheet of material.