Laser processing apparatus

Abstract

A laser beam irradiation unit of a laser processing apparatus includes a laser oscillator that oscillates a laser, a Y-axis scanner that executes a high-speed scan with a laser beam emitted from the laser oscillator in a Y-axis direction, an X-axis scanner that executes processing feed of the laser beam emitted from the laser oscillator in an X-axis direction, and a beam condenser. The Y-axis scanner is selected from any of an AOD, a resonant scanner, and a polygon scanner and the X-axis scanner is selected from a galvano scanner and a resonant scanner.

What is claimed is: 
     
         1 . A laser processing apparatus comprising:
 a chuck table that holds a workpiece and includes a holding surface defined by an X-axis and a Y-axis; and   a laser beam irradiation unit that irradiates the workpiece held by the chuck table with a laser beam and forms a broken layer, wherein   the laser beam irradiation unit includes
 a laser oscillator that oscillates a laser, 
 a Y-axis scanner that executes a high-speed scan with a laser beam emitted from the laser oscillator in a Y-axis direction, 
 an X-axis scanner that executes processing feed of the laser beam emitted from the laser oscillator in an X-axis direction, and 
 a beam condenser, 
   a spot diameter (D) of the laser beam with which the workpiece is irradiated is set to 5 to 60 μm, an overlap rate (K) of a spot of the laser beam is set to 0.70 to 0.99, a scan speed (Vy) in the Y-axis direction is set to 1 to 300 m/s, and energy (E) of the laser beam per one pulse is set to 0.07 to 50 μJ,   repetition frequency (H) of the laser beam is set to
     H=Vy/{D ·(1− K )} MHz,
 
   when a width of the scan by the Y-axis scanner is defined as L mm, a scan speed (Vx) in the X-axis direction is set to
     Vx=D ·(1− K )· Vy/L  mm/s, and
 
   average output power (P) of the laser beam is set to
     P=E·Vy/{D ·(1− K )} W.
 
   
     
     
         2 . The laser processing apparatus according to  claim 1 , wherein
 the Y-axis scanner is selected from a group consisting of an acousto-optic deflector, a resonant scanner, and a polygon scanner and the X-axis scanner is selected from a group consisting of a galvano scanner, a resonant scanner, and an X-axis direction feed mechanism that moves the chuck table in the X-axis direction.   
     
     
         3 . The laser processing apparatus according to  claim 1 , wherein
 the workpiece is a double-layer substrate in which a light emitting layer is stacked over an upper surface of a sapphire substrate with intermediary of a buffer layer and a transfer substrate is disposed to face the light emitting layer, and the laser beam is transmitted through the sapphire substrate and breaks the buffer layer.   
     
     
         4 . The laser processing apparatus according to  claim 3 , wherein
 a wavelength of the laser beam is 143 to 266 nm.