Vibration Assistant Polishing Module for SiC Wafers
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Solution Overview
Problem
The polishing process for SiC wafers is inefficient due to their high hardness, resulting in a low material removal rate and prolonged processing time, which increases manufacturing costs, especially for larger wafers.
Innovation Solution
A vibration assistant polishing module that combines an adjustable eccentricity mechanism and a linear guide way mechanism to generate a low-frequency vibration, enhancing the material removal rate by increasing the effective grains number in the polishing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional polishing process is used for SiC wafers, then the polishing can be completed with standard equipment, but the material removal rate is extremely low (not larger than 0.2 μm/h) and processing time exceeds 2 hours
Solution Approach 1:
The patent applies mechanical vibration to the workpiece carrier tray through an adjustable eccentricity mechanism driven by a motor. The vibration causes the workpiece to oscillate during polishing, increasing the contact between abrasive grains and the workpiece surface. This enhances the material removal rate from 0.2 μm/h to over 0.4 μm/h (50-100% improvement) and reduces processing time from over 2 hours to under 1 hour.
2Productivity
If larger SiC wafers (≥4 inches) are processed, then the capacity and market potential are improved, but the polishing process becomes even slower and cost increases to account for more than half of manufacture cost
Solution Approach 1:
The vibration assistant polishing module is designed to be compatible with large-size SiC wafers (≥4 inches). The mechanical vibration enhances polishing efficiency across the entire wafer surface, reducing processing time and cost for large wafers specifically, thereby improving the economic feasibility of manufacturing large-area SiC devices.
3Manufacturing precision
If SiC wafers are polished to achieve required surface quality, then the material's excellent properties (voltage resistance, heat resistance, low loss) are preserved, but the process takes more than 2 hours due to SiC's superhard nature (9.25-9.5 Mohs hardness)
Solution Approach 1:
The mechanical vibration generated by the adjustable eccentricity mechanism causes the workpiece to oscillate during polishing, increasing the effective contact between abrasive grains and the workpiece surface. This enhances material removal rate while maintaining surface quality requirements for SiC wafers, reducing polishing duration from over 2 hours to under 1 hour.
Solution Approach 2:
The vibration assistant polishing module generates periodic low-frequency vibrations (horizontal radial amplitude) on the workpiece carrier tray. This periodic motion creates varying contact pressure and angle between abrasive grains and workpiece surface, preventing grain clogging and maintaining consistent material removal rate throughout the polishing process, thereby achieving both high precision and reduced duration.
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 module significantly increases the material removal rate by 50-100% and reduces processing time, thereby improving process efficiency and lowering manufacturing costs.
Implementation Method 1
an adjustable eccentricity mechanism, further comprising: a base which is connected to the power shaft of the motor, and is coupled to the second end of the linkage via a pivot shaft while allowing the pivot shaft to be eccentrically disposed to the power shaft; wherein, the power shaft drives the base to rotate so as to bring along the linkage to swing eccentrically
Implementation Method 2
power provided from the power shaft is transmitted to the slide via the linkage for enabling the slide to move linearly in a direction parallel to a first direction according to the limitation from guide seat, and thereby a low frequency vibration with horizontal radial amplitude is generated on the workpiece carrier tray
Implementation Method 3
a polishing disk, disposed for enabling the same to be rotatable... the low frequency vibration is generated on the surface of the workpiece which is engaged with the polishing disk... enhancing the material removal rate by increasing the effective grains number in the polishing process
Data Source
AI summary
A vibration assistant polishing module which comprises a polishing disk, a workpiece carrier tray, a linear guide way mechanism, a linkage, a motor and an adjustable eccentricity mechanism. The linear guide way mechanism includes a slide, a guide seat and a guide rod. The slide is pivot jointed with workpiece carrier tray and engaged in guide seat. The adjustable eccentricity mechanism comprises a base which is connected with a power shaft of the motor, and a pivot shaft of base and linkage is eccentric to the power shaft. The power shaft drives the base rotating and the linkage swinging eccentrically, and the slide moves linearly according to the limitation from guide seat, and a horizontal radial vibration and low frequency vibration is generated on the workpiece carrier tray, so the low frequency vibration is generated on the surface of the workpiece which is touched with the polishing disk.