Laser Annealing Pulse Sequencing for Low-Damage Silicon Crystallization
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Solution Overview
Problem
Existing laser annealing processes often cause damage to semiconductor layers due to excessive heat and hydrogen release during crystallization, affecting film quality.
Innovation Solution
A laser annealing apparatus and method that employs a controlled sequence of laser beams with adjusted timings and powers, including a first low-power beam for dehydrogenation followed by higher-power beams for crystallization, to minimize heat exposure and hydrogen release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single high-power laser beam is used for crystallization, then crystallization efficiency is improved, but semiconductor layer damage increases due to excessive heat and hydrogen release
Solution Approach 1:
The laser beam is divided into multiple beams with different powers and timings. A first low-power laser beam performs dehydrogenation before a second high-power laser beam performs crystallization, preventing damage from simultaneous high heat and hydrogen release
Solution Approach 2:
The first low-power laser beam performs dehydrogenation as a preliminary step before the second high-power laser beam performs crystallization. This preliminary removal of hydrogen prevents explosive release during the high-power crystallization process
2Productivity
If laser power is increased to improve crystallization speed, then productivity is improved, but film quality deteriorates due to heat damage
Solution Approach 1:
The crystallization process is segmented into two stages: first a low-power beam for dehydrogenation, then a high-power beam for rapid crystallization. This segmentation allows high-speed crystallization without compromising film quality
Solution Approach 2:
Laser power parameters are dynamically changed during the process - starting with low power for dehydrogenation, then switching to high power for crystallization. This parameter optimization maintains both speed and quality
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
Prevents damage to semiconductor layers by effectively reducing hydrogen content and improving film quality through controlled laser annealing, enhancing electron mobility in poly silicon.
Implementation Method 1
A crystallization process of irradiating a laser beam to the amorphous silicon is desired to form the poly silicon
Implementation Method 2
irradiating a laser beam to the amorphous silicon is desired to form the poly silicon
Implementation Method 3
beam mixer optics that outputs a processing beam by mixing the plurality of laser beams of which output timings are adjusted
Implementation Method 4
focus optics that outputs the processing beam of which focus is adjusted
Data Source
AI summary
A laser annealing apparatus includes a plurality of lasers, a laser controller that controls the plurality of lasers such that a plurality of laser beams generated from the plurality of lasers is emitted at different timings, beam mixer optics that outputs a processing beam by mixing the plurality of laser beams of which output timings are adjusted, and focus optics that outputs the processing beam of which focus is adjusted. The processing beam includes a first processing laser beam having a first pulse, a second processing laser beam having a second pulse following the first pulse, and a third processing laser beam having a third pulse following the second pulse. A first peak of the first pulse is smaller than a second peak of the second pulse, and a third peak of the third pulse is smaller than the second peak.