Laser Processing Apparatus Zigzag Wafer Division
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Solution Overview
Problem
The division of optical device wafers using modified layers or laser processing grooves results in flat division surfaces, leading to reduced luminance due to light confinement within the substrate.
Innovation Solution
A laser processing apparatus with a pulsed laser beam irradiator, a condenser, and a beam splitting means that includes a half-wave plate, birefringent lens, and a quarter-wave plate to split the laser beam into ordinary and extraordinary light, allowing for offset focus points and forming zigzag cut surfaces, enhancing luminance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a modified layer or laser processing groove is formed for wafer division, then the wafer can be divided along streets, but the division surface becomes flat and light from the light emitting layer is confined in the substrate, causing lowering of luminance
Solution Approach 1:
The patent applies curvature by forming a zigzag cut surface instead of a flat division surface. The laser beam is irradiated at an inclined angle to create a stepped, non-planar division surface that prevents light confinement and improves luminance while maintaining wafer division functionality
Solution Approach 2:
The patent introduces asymmetry by using inclined laser beam irradiation to create an uneven zigzag pattern on the division surface. This asymmetric structure breaks the symmetry of light propagation paths, preventing constructive interference and light trapping that occurs with flat surfaces
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The apparatus effectively enhances the luminance of optical devices by forming zigzag cut surfaces during wafer division, preventing light confinement and improving optical device performance.
Implementation Method 1
a half-wave plate that rotates a plane of polarization of the pulsed laser beam oscillated by the pulsed laser beam oscillating means
Implementation Method 2
a birefringent lens that splits the pulsed laser beam that has passed through the half-wave plate into ordinary light and extraordinary light
Implementation Method 3
a quarter-wave plate that is disposed between the birefringent lens and the condenser and changes a linearly-polarized pulsed laser beam oscillated by the pulsed laser beam oscillating means to a circularly-polarized pulsed laser beam
Implementation Method 4
a condenser that condenses the pulsed laser beam oscillated by the pulsed laser beam oscillating means and irradiates the workpiece held by the chuck table with the laser beam
Implementation Method 5
a modified layer is continuously formed inside the wafer along streets by irradiating the wafer with the pulsed laser beam having such a wavelength as to be transmitted through the wafer along the streets from one surface side of the wafer with the light focus point positioned inside the wafer
Implementation Method 6
a laser processing groove is formed along the streets by irradiating the wafer with a pulsed laser beam having such a wavelength as to be absorbed by the wafer along the streets
Data Source
AI summary
A laser processing apparatus includes a beam splitting unit disposed between a pulsed laser beam oscillating unit and a condenser. The beam splitting unit includes a half-wave plate that rotates the plane of polarization of a pulsed laser beam, a birefringent lens that splits the pulsed laser beam that has passed through the half-wave plate into ordinary light and extraordinary light, the birefringent lens being formed by joining two kinds of crystalline bodies to each other across a curved plane of a concave surface and a convex surface, and a splitting angle adjusting unit that moves the birefringent lens in a direction orthogonal to the pulsed laser beam that has passed through the half-wave plate to change the angle of incidence with respect to the curved plane and adjust a beam splitting angle.