Laser Beam Shaping for Uniform Semiconductor Irradiation
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Solution Overview
Problem
Conventional laser irradiation techniques for semiconductor material surfaces face issues such as decreased processing speed, increased production costs, non-uniform dopant activation, and surface quality due to the need for scanning or stepping of the laser beam, which results in overlap and energy density fluctuations.
Innovation Solution
A laser apparatus that shapes a primary laser beam into multiple secondary beams using a plurality of apertures matching the semiconductor material layer's size and shape, with an optical system for superposing these beams to irradiate the region uniformly, eliminating the need for scanning and reducing optical elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a shadow mask is used to shape the laser beam spot, then the laser spot size can be controlled, but the processing speed decreases and production cost increases due to the need for scanning or stepping
Solution Approach 1:
The patent divides a single large laser beam into multiple smaller beam spots using a beam splitting optical system. This segmentation allows simultaneous irradiation of multiple regions on the semiconductor wafer, eliminating the need for scanning or stepping operations while maintaining precise spot size control through the use of multiple apertures in the mask structure.
2Area of stationary object
If the laser spot scans or steps over the pattern, then the entire die or pattern can be irradiated, but non-uniformities in dopant activation rate or depth and surface quality are generated due to fluctuations in laser energy density
Solution Approach 1:
By segmenting the laser beam into multiple fixed beam spots that cover the entire irradiation area simultaneously, the patent eliminates scanning-induced energy density fluctuations. Each beam spot maintains stable energy density, ensuring uniform dopant activation rate and depth across the entire pattern without the non-uniformities caused by sequential scanning.
Solution Approach 2:
The patent merges multiple beam spots into a comprehensive irradiation pattern that covers the entire die or pattern area. This combining approach achieves complete coverage while maintaining uniform energy distribution across all regions, avoiding the non-uniformities that arise from sequential scanning operations.
3Area of stationary object
If successive laser spots overlap when the pattern size is greater than the laser beam spot, then the entire pattern can be covered, but non-uniformities in dopant activation rate or depth and surface quality occur
Solution Approach 1:
The patent segments the laser beam into multiple non-overlapping beam spots that precisely cover the pattern area. By using a mask with multiple apertures positioned to create adjacent but non-overlapping spots, the system achieves complete pattern coverage while preventing the overlapping-induced non-uniformities in dopant activation and surface quality.
4Temperature
If the laser spot size is much smaller than the die size due to high energy density requirements, then the irradiation process can be performed, but the processing speed decreases due to the need for scanning
Solution Approach 1:
The patent segments the laser beam into multiple spots that can simultaneously irradiate different regions of the die. This allows the system to maintain high energy density in each spot (necessary for effective irradiation) while processing the entire die in parallel, thereby eliminating the time-consuming scanning operations and significantly improving processing speed.
Solution Approach 2:
The patent transitions from sequential one-dimensional scanning to simultaneous two-dimensional parallel processing by creating multiple beam spots across the die surface. This dimensional change allows high energy density to be maintained in each spot while covering the entire die area concurrently, resolving the contradiction between energy density requirements and processing speed.
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 approach enhances processing speed, reduces production costs, and achieves uniform dopant activation and surface quality by ensuring consistent energy distribution across the semiconductor material layer without overlap, while minimizing the number of optical elements required.
Implementation Method 1
an optical system adapted for superposing the secondary laser beams to irradiate said common region
Implementation Method 2
a means for shaping the primary laser beam into a plurality of secondary laser beams by a means for shaping comprising a plurality of apertures of which the shape and/or size corresponds to the shape and/or size of a common region of the semiconductor material layer to be irradiated
Data Source
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AI summary
The present invention is related to an apparatus for irradiating semiconductor material comprising: - a laser generating a primary laser beam; - an optical system; - and a means for shaping the primary laser beam, comprising a plurality of apertures for shaping the primary laser beam into a plurality of secondary laser beams; characterized in that the shape and/or size of the individual apertures corresponds to the shape and/or size of a common region of a semiconductor material layer to be irradiated, and that the optical system is adapted for superposing the secondary laser beams to irradiate said common region. Further, the present invention is related to the use of such an apparatus in semiconductor device manufacturing.