SiC Semiconductor Laser Annealing Surface Roughness Control
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Solution Overview
Problem
Silicon carbide semiconductor devices manufactured using laser annealing often exhibit surface roughness in the pad electrode, leading to increased void formation during die bonding, which reduces yield and requires additional processing steps to mitigate surface roughness.
Innovation Solution
The method involves controlling the arithmetic mean roughness of the second electrode's surface to less than 0.2 μm by adjusting the laser annealing conditions, specifically the laser irradiation intensity between 1.5 J/cm2 and 2.4 J/cm2, to suppress void generation during die bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser annealing is used to establish ohmic contact, then the manufacturing efficiency is improved, but the surface roughness of the electrode increases leading to void formation
Solution Approach 1:
The patent applies parameter changes by optimizing laser annealing conditions (irradiation intensity, number of scans, scan speed) to control the surface roughness of the electrode. By adjusting these parameters, the method achieves smooth surfaces (Ra ≤ 0.2 μm) while maintaining the efficiency benefits of laser annealing, thus resolving the contradiction between manufacturing efficiency and surface precision
2Manufacturing precision
If additional processing steps are added to reduce surface roughness, then the manufacturing precision is improved, but the device complexity and cost increase
Solution Approach 1:
The patent applies preliminary action by optimizing the laser annealing process to produce smooth electrode surfaces directly during the ohmic contact formation step. This preliminary optimization eliminates the need for subsequent surface treatment steps, thereby maintaining high manufacturing precision while avoiding increased device complexity and cost
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 effectively reduces void occupancy to 5% or lower, improving the manufacturing yield by maintaining low surface roughness without increasing the number of processing steps or costs.
Implementation Method 1
establishing ohmic contact between the silicon carbide substrate and the first electrode by irradiating the first electrode with laser beams
Data Source
AI summary
A method of manufacturing a silicon carbide semiconductor device includes the steps of preparing a silicon carbide substrate, forming a first electrode on the silicon carbide substrate, establishing ohmic contact between the silicon carbide substrate and the first electrode by irradiating the first electrode with laser beams, and forming a second electrode on the first electrode. In the step of establishing ohmic contact, a surface of the first electrode is irradiated with laser beams such that arithmetic mean roughness of a surface of the second electrode is not greater than 0.2 μm.