SiC Laser Doping with Pulse Width Control
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Solution Overview
Problem
Conventional laser doping methods for silicon carbide (SiC) struggle to achieve sufficient doping depth for p-type dopants, particularly aluminum, which is essential for forming effective semiconductor devices, as they often result in thermal damage and lattice defects, limiting the electrical characteristics of SiC-based power devices.
Innovation Solution
A laser doping apparatus and method that incorporates a pulse laser system with a time-domain pulse waveform controller, including an optical pulse stretcher, to extend the pulse width of the laser beam, allowing deeper penetration of dopants into the SiC substrate without causing thermal damage, thereby enhancing doping depth and electrical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If conventional laser doping methods are used to dope SiC, then doping process can be performed, but doping depth is insufficient (only 30-40 nm for phosphor and aluminum)
Solution Approach 1:
The patent changes the temporal parameter of the laser pulse by extending the pulse width from conventional narrow pulses to microsecond-order long pulses. This parameter change allows the laser energy to be delivered over a longer duration, enabling dopants to penetrate deeper into the SiC substrate (achieving 120 nm doping depth) while maintaining controlled thermal effects that preserve electrical characteristics.
2Reliability
If conventional laser doping methods are used, then doping can be performed, but thermal damage and lattice defects occur limiting electrical characteristics
Solution Approach 1:
The patent employs periodic pulsed laser irradiation with microsecond-order pulse widths. This periodic action allows the material to undergo repeated cycles of energy absorption and thermal relaxation, enabling cumulative dopant penetration while preventing excessive heat accumulation that would cause thermal damage and lattice defects, thus preserving electrical characteristics.
3Length of moving object
If pulse width is extended to increase doping depth, then deeper doping is achieved, but thermal damage may increase
Solution Approach 1:
The patent dynamically optimizes the laser pulse width to the microsecond order, creating a dynamic balance between energy delivery duration and thermal diffusion time. This dynamic parameter selection enables the laser energy to penetrate deeper into the substrate (120 nm doping depth) while the pulse duration is sufficiently short to prevent excessive heat accumulation and thermal damage.
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 approach significantly improves doping depth for p-type dopants in SiC from 40 nm to 120 nm, facilitating the formation of efficient p-n junctions and enhancing the electrical characteristics of SiC-based semiconductor devices.
Implementation Method 1
a laser system including at least one laser device configured to output the pulse laser beam to be transmitted by the dopant-containing solution
Implementation Method 2
a time-domain pulse waveform changing apparatus configured to control a time-domain pulse waveform of the pulse laser beam
Data Source
AI summary
The laser doping apparatus may irradiate a predetermined region of a semiconductor material with a pulse laser beam to perform doping. The laser doping apparatus may include: a solution supplying system configured to supply dopant-containing solution to the predetermined region, and a laser system including at least one laser device configured to output the pulse laser beam to be transmitted by the dopant-containing solution, and a time-domain pulse waveform changing apparatus configured to control a time-domain pulse waveform of the pulse laser beam.