Laser Irradiation Apparatus Polarization Control
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Solution Overview
Problem
The existing laser irradiation apparatuses using two laser light sources with different polarization states can cause adverse effects on the object being irradiated due to the difference in polarization states, leading to nonuniform crystal grain sizes in semiconductor substrates during laser annealing.
Innovation Solution
A laser irradiation apparatus is designed with a first laser light source emitting a polarized pulse laser beam and a second laser light source emitting a polarized pulse laser beam with a different polarization state, both guided through the same optical path using an optical path combining member. A polarization control member, comprising first and second polarization control portions, adjusts the polarization states of the beams to ensure they are mixed on the surface, preventing adverse effects from polarization differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If two laser light sources with different polarization states are used to increase power and frequency, then the power and frequency of the laser beam are increased, but the object to be irradiated is adversely affected due to polarization state differences
Solution Approach 1:
The patent changes the polarization state parameter by introducing a polarization control member (quarter-wave plate) that converts the polarization states of both laser beams to be substantially equal before they reach the object. This parameter transformation eliminates the harmful effect of polarization differences while maintaining the power and frequency benefits of using two laser sources.
2Power
If two laser light sources with different polarization states are used to increase power and frequency, then the power and frequency of the laser beam are increased, but the crystal grain sizes in semiconductor substrates become nonuniform
Solution Approach 1:
The polarization control member transforms the polarization parameter of the laser beams to be substantially equal, ensuring uniform interaction with the semiconductor substrate during laser annealing. This uniformity prevents nonuniform crystal grain sizes while maintaining the high power benefits of dual laser sources.
3Productivity
If an optical path combining member is used to guide both laser beams through the same optical path, then the frequency and power are doubled, but the polarization state differences cause adverse effects on the irradiated object
Solution Approach 1:
The polarization control member is positioned in the combined optical path to transform the polarization states of both laser beams to be substantially equal. This allows the system to maintain doubled frequency and power from the optical path combining while eliminating the harmful polarization differences that would otherwise affect the irradiated object.
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
This setup ensures stable crystalline semiconductor formation by evenly mixing the polarization states of the laser beams, preventing nonuniformity in crystal grain sizes and enhancing the stability of laser irradiation processes like laser annealing.
Implementation Method 1
The optical path combining optical member 35 can guide the pulsed laser beams to pass through the same optical path using the fact that the polarization directions of the pulsed laser beams from the first laser resonator 31 and the second laser resonator 32 are at 90° to each other. The optical path combining optical member 35 is a polarization beam splitter, for example, which reflects a pulsed laser beam polarized linearly in a perpendicular direction on the plane of the paper of FIG. 9 and transmits a pulsed laser beam polarized linearly in an up and down direction on the plane of the paper of FIG. 9.
Implementation Method 2
a polarization control member which is arranged in an arrangement direction perpendicular to a traveling direction of the pulsed laser beam from the optical path combining optical member and which includes a first polarization control portion which controls a polarization state of beam components of the pulsed laser beam from the optical path combining optical member and a second polarization control portion which controls a polarization state of beam components of the pulsed laser beam from the optical path combining optical member so that the polarization state of the beam components of the pulsed laser beam from the optical path combining optical member is different from the polarization state of the first polarization control portion
Data Source
AI summary
A laser irradiation apparatus is provided in which the occurrence of adverse effects on an object to be irradiated with a laser beam due to the difference in the polarization state between pulsed laser beams can be prevented or significantly reduced when the pulsed laser beams emitted from two laser light sources are guided to pass through the same optical path for irradiation of an object to be irradiated with the pulsed laser beams. The laser irradiation apparatus is provided with a first laser light source 3, a second laser light source 4, an optical path combining optical member 7 which guides the pulsed laser beams emitted from the first laser light source 3 and the second laser light source 4 to pass through the same optical path, and a polarization control member 9 which controls polarization state of the pulsed laser beam from the optical path combining optical member 7. The polarization control member 9 includes a first polarization control portion 13 and a second polarization control portion 15 through which beam components of the pulsed laser beam pass. The polarization states of the beam components that have passed through the first polarization control portion 13 and the beam components that have passed through the second polarization control portion 15 become different from each other. The beam components in different polarization states are superimposed on each other on a surface to be irradiated with the laser beam of the object to be irradiated with the laser beam.