Laser Surface Ablation for Smoother Silicon Carbide Wafers
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Solution Overview
Problem
Current methods for fabricating power semiconductor devices from wide bandgap semiconductor materials, such as silicon carbide, incur significant material losses and consumable tool losses due to the structural properties of crystalline boules and separation methods, leading to rough and uneven surfaces that require extensive grinding and polishing, which are time-consuming and costly.
Innovation Solution
A laser-based system is used for surface processing of semiconductor workpieces, employing one or more lasers to ablate and smooth the exposed surfaces of semiconductor wafers, reducing thickness and achieving a surface roughness of 0.5 nanometers to 180 nanometers without using consumable tools, thereby minimizing material and operational costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional grinding and polishing methods are used to process semiconductor wafer surfaces, then surface smoothness can be achieved, but material loss increases and processing time extends
Solution Approach 1:
The patent replaces traditional mechanical grinding and polishing systems with a laser-based processing system. The laser beam selectively removes material from the wafer surface through ablation, achieving smooth surfaces without the need for mechanical contact. This substitution eliminates consumable tools and significantly reduces material loss while maintaining high manufacturing precision.
Solution Approach 2:
The patent utilizes controllable laser parameters (power, pulse duration, wavelength, scanning speed) to optimize the surface processing. By adjusting these parameters, the system achieves precise material removal with minimal loss and produces surfaces with controlled roughness, eliminating the need for multiple grinding and polishing passes.
2Manufacturing precision
If traditional grinding and polishing methods are used to process semiconductor wafer surfaces, then surface smoothness can be achieved, but processing time extends
Solution Approach 1:
The laser-based system processes surfaces at the speed of light, eliminating the slow mechanical contact of traditional grinding and polishing. The laser can rapidly ablate material and smooth surfaces in a single pass, dramatically reducing processing time while achieving the required surface quality for semiconductor devices.
Solution Approach 2:
The laser processing operates continuously as the laser beam scans across the wafer surface, removing material and smoothing the surface in one uninterrupted action. This eliminates the multiple sequential steps (coarse grinding, fine grinding, polishing) required by traditional methods, significantly reducing total processing time.
3Productivity
If traditional separation methods are used to remove wafers from boules, then wafer separation can be achieved, but surface quality deteriorates requiring extensive processing
Solution Approach 1:
The laser performs preliminary surface conditioning immediately after wafer separation from the boule. By applying the laser beam to the freshly separated surface, the system pre-smooths and prepares the surface for subsequent processing steps, eliminating the need for extensive grinding and polishing and improving overall productivity.
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 laser-based system effectively smooths semiconductor surfaces, reducing material loss and operational costs by avoiding consumable tool wear, while maintaining high precision and efficiency in semiconductor fabrication.
Implementation Method 1
ablating, with one or more lasers, an exposed surface resulting from the removal process to remove material from the exposed surface
Data Source
AI summary
Systems and methods for laser-based surface processing operations on a wide bandgap semiconductor wafer, such as a silicon carbide semiconductor wafer, are provided. In one example, a method includes removing a wide bandgap semiconductor wafer from a boule using a removal process. The method includes ablating, with one or more lasers, an exposed surface resulting from the removal process to remove material from the exposed surface, wherein ablating, with one or more lasers, the exposed surface reduces a thickness of semiconductor material (e.g., by about 25 microns or greater).