Laser dicing method

Abstract

A laser dicing method includes: placing a workpiece substrate on a stage; generating a clock signal; emitting a pulse laser beam synchronous with the clock signal; switching irradiation and non-irradiation of the workpiece substrate with the pulse laser beam in a unit of light pulse in synchronization with the clock signal to perform first irradiation of the pulse laser beam on a first straight line by controlling the pulse laser beam using a pulse picker; performing second irradiation of the pulse laser beam on a second straight line, which is adjacent to the first straight line in a substantially parallel fashion, after the first irradiation; and forming a crack reaching a workpiece substrate surface on the workpiece substrate by the first irradiation and the second irradiation.

What is claimed is: 
     
         1 . A laser dicing method comprising:
 placing a workpiece substrate, which includes a metallic film on a surface thereof, on a stage;   generating a clock signal;   emitting a pulse laser beam synchronous with the clock signal;   moving relatively the workpiece substrate and the pulse laser beam;   switching irradiation and non-irradiation of the workpiece substrate with the pulse laser beam in a unit of light pulse in synchronization with the clock signal to perform first irradiation of the pulse laser beam from a side of the metallic film on a first straight line by controlling passage and cutoff of the pulse laser beam using a pulse picker;   switching the irradiation and non-irradiation of the workpiece substrate with the pulse laser beam in a unit of light pulse in synchronization with the clock signal to perform second irradiation of the pulse laser beam from a side of the metallic film on a second straight line, the second straight line is adjacent to the first straight line in a substantially parallel fashion, by controlling the passage and cutoff of the pulse laser beam using the pulse picker after the first irradiation; and   forming a crack reaching a workpiece substrate surface on the workpiece substrate at the same time as a removal of the metallic film by the first irradiation and the second irradiation,   wherein the crack is continuously formed on the workpiece substrate surface at the same time as the removal of the metallic film by controlling irradiation energy of the pulse laser beam, a processing point depth of the pulse laser beam, and lengths of an irradiation region and a non-irradiation region of the pulse laser beam.   
     
     
         2 . The laser dicing method according to  claim 1 , wherein the second irradiation is performed at a processing point depth identical to that of the first irradiation. 
     
     
         3 . The laser dicing method according to  claim 1 , wherein an LED is formed on a surface of the workpiece substrate on a side opposite to the metallic film.