Wafer Edge Grinding with Plasma Pretreatment for Shape Accuracy
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Solution Overview
Problem
The existing grinding techniques for SiC wafers result in shape accuracy deterioration due to grindstone abrasion and frequent maintenance, leading to inefficiencies in the grinding operation.
Innovation Solution
A grinding apparatus equipped with plasma generators that irradiate the outer circumferential edge of the wafer with plasma before grinding, utilizing a swiveling device and grinders to optimize conditions for plasma irradiation and grinding, and incorporating inspection devices for surface and crystal states to enhance shape accuracy and operation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a grindstone is used to rough-polish the SiC wafer, then the outer circumferential portion can be ground, but the grindstone abrades easily and its shape changes, causing shape accuracy deterioration
Solution Approach 1:
The patent applies preliminary action by performing plasma irradiation on the outer circumferential portion of the SiC wafer before grinding. This plasma treatment modifies the surface properties of the SiC, making it easier to grind while maintaining shape accuracy. The plasma-irradiated surface allows for efficient material removal without causing grindstone abrasion, thus resolving the contradiction between productivity and manufacturing precision.
2Productivity
If a grindstone is used to rough-polish the SiC wafer, then the outer circumferential portion can be ground, but frequent maintenance and replacement of the grindstone is required
Solution Approach 1:
The plasma irradiation is performed as a preliminary step before grinding, which modifies the SiC surface to be more grindable. This preprocessing eliminates the need for frequent grindstone maintenance and replacement, as the plasma-treated surface does not cause abrasion to the grindstone. Consequently, productivity is maintained while maintenance time is significantly reduced.
3Ease of manufacture
If the outer circumferential edge of the SiC wafer is ground directly, then the wafer can be processed, but the sharp edge and hard-to-cut material cause grindstone abrasion
Solution Approach 1:
The patent changes the physical and chemical parameters of the SiC wafer surface through plasma irradiation. The plasma treatment modifies the surface energy, hardness, and reactivity of the SiC outer circumferential portion, transforming it from a hard-to-cut material with sharp edges to a more grindable state. This parameter change eliminates grindstone abrasion while improving ease of manufacture.
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 plasma-assisted grinding improves shape accuracy and operational efficiency by softening the wafer edges, reducing grindstone abrasion, and optimizing grinding conditions, thereby enhancing the precision and productivity of the process.
Implementation Method 1
at least one plasma generator configured to irradiate, before an outer circumferential edge of a wafer is ground, at least part of the outer circumferential edge with plasma
Data Source
AI summary
To make an improvement in the shape accuracy of a wafer shaped in the grinding operation after pretreatment and make an improvement in the efficiency of grinding operation of a wafer. A grinding apparatus includes at least one plasma generator configured to irradiate, before an outer circumferential edge of a wafer is ground, at least part of the outer circumferential edge with plasma.