Tilted Deflector Beam Homogenizer for Laser Loss Reduction
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Solution Overview
Problem
Existing beam homogenizers, such as those using optical waveguides or light pipes, face challenges in maintaining consistent energy distribution and preventing laser beam loss due to fluctuations in laser oscillation conditions, leading to defects in semiconductor film annealing processes during mass production of semiconductor devices.
Innovation Solution
A beam homogenizer with a deflector at the entrance of an optical waveguide, where the reflection planes are tilted to the optical axis, allowing for effective condensation of the laser beam and reducing loss, combined with an optical waveguide that homogenizes the energy distribution by repeated reflections, and an angle adjusting mechanism to optimize the tilt angle for high homogeneity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a cylindrical lens array is used as a beam homogenizer, then the energy distribution can be homogenized, but the position of the homogeneous plane changes when beam parameters fluctuate, causing energy density fluctuation
Solution Approach 1:
The optical waveguide divides the incident laser beam into multiple rays that undergo repeated reflections. By segmenting the beam path and controlling the reflection geometry, the system creates a homogeneous energy distribution at the exit face that is insensitive to input beam parameter fluctuations.
Solution Approach 2:
The patent transitions from using cylindrical lenses (2D homogenization) to an optical waveguide with tilted reflection planes (3D path control). This dimensional change allows the beam to undergo multiple reflections along the waveguide length, creating a more robust homogenization effect that stabilizes the homogeneous plane position.
2Manufacturing precision
If the distance between reflection planes in the optical waveguide is reduced to increase beam division, then homogeneity improves, but laser beam loss increases due to inability to condense the beam properly
Solution Approach 1:
The patent optimizes the distance between reflection planes and the tilt angle of the reflection surfaces to achieve the optimal balance between beam division and condensation. By carefully selecting these geometric parameters, the system maximizes homogeneity while minimizing beam loss through the tilted reflection geometry that facilitates better beam condensation.
3Productivity
If the oscillation power of the laser is increased to improve productivity, then mass production capability improves, but the fluctuation in beam parameters increases, affecting homogeneity
Solution Approach 1:
The optical waveguide structure is designed in advance to compensate for beam parameter fluctuations that occur at high oscillation powers. The repeated reflections and tilted geometry pre-condition the beam to achieve homogeneity even when input parameters vary, cushioning against the negative effects of high-power oscillation instability.
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 solution ensures a homogeneous beam spot is formed at the exit of the optical waveguide, reducing laser beam loss and maintaining consistent energy distribution, enabling effective semiconductor film annealing under constant conditions, thereby enhancing the homogeneity of crystallinity and stability in semiconductor device production.
Implementation Method 1
When an optical waveguide is used as the beam homogenizer, a laser beam entering the optical waveguide is repeatedly reflected inside the optical waveguide.
Implementation Method 2
the deflector has a pair of reflection planes tilted to the optical axis of the laser beam
Data Source
AI summary
The present invention is to provide a beam homogenizer, a laser irradiation apparatus, and a method for manufacturing a semiconductor device, which can suppress the loss of a laser beam and form a beam spot having homogeneous energy distribution constantly on an irradiation surface without being affected by beam parameters of a laser beam. A deflector is provided at an entrance of an optical waveguide or a light pipe used for homogenizing a laser beam emitted from a laser oscillator. A pair of reflection planes of the deflector is provided so as to have a tilt angle to an optical axis of the laser beam, whereby the entrance of the optical waveguide or the light pipe is expanded. Accordingly, the loss of the laser beam can be suppressed. Moreover, by providing an angle adjusting mechanism to the deflector, a beam spot having homogeneous energy distribution can be formed at an exit of the optical waveguide.