Wafer Beveling Method Reducing Corner Burrs
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Solution Overview
Problem
Conventional wafer mirror surface beveling methods often result in corner burrs at the boundary between the main surface and the chamfered surface, leading to potential debris generation during washing and subsequent manufacturing steps.
Innovation Solution
A wafer mirror surface beveling method that adjusts the angle between the polishing pad and the wafer's main surface to be smaller than or equal to the chamfer angle, with a polishing pad mounting jig oscillating along an inclined surface, reducing corner burrs and over-polishing by maintaining constant contact with the chamfered surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the polishing pad is pressed against the chamfered surface at an angle greater than the chamfer angle (conventional method), then the chamfered surface can be polished to a mirror state, but corner burrs are generated at the boundary between the main surface and chamfered surface
Solution Approach 1:
The patent changes the critical parameter of polishing pad angle from being greater than the chamfer angle (conventional) to being smaller than or equal to the chamfer angle. This parameter change eliminates corner burr generation while maintaining mirror surface quality on the chamfered surface, resolving the contradiction between surface flatness and corner burr prevention
Solution Approach 2:
The patent inverts the conventional polishing approach by reversing the angle relationship. Instead of polishing pad angle > chamfer angle, the method uses polishing pad angle ≤ chamfer angle. This inversion prevents the polishing pad from contacting the main surface at the boundary region, thereby eliminating corner burr generation while still achieving mirror polishing on the chamfered surface
2Object-generated harmful factors
If corner burrs are present on the wafer, then debris is generated during washing and subsequent manufacturing steps, but removing corner burrs requires additional processing steps
Solution Approach 1:
The patent applies preliminary action by preventing corner burr formation during the mirror surface beveling process itself. By controlling the polishing pad angle to be smaller than or equal to the chamfer angle, corner burrs are prevented from generating in the first place, eliminating the need for subsequent corner burr removal steps and reducing overall process complexity
Solution Approach 2:
The patent converts the potential harm of corner burrs into a benefit by using the polishing process parameters to prevent their formation. The controlled polishing pad angle, which limits the polishing action to the chamfered surface only, transforms what would be a harmful byproduct (corner burrs) into a quality feature (burr-free surfaces), thereby reducing debris generation without adding processing steps
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 method effectively reduces or inhibits corner burrs by at least 180 μm, achieving acceptable flatness with an ESFQRmax of 45 nm or less, thereby minimizing debris generation and improving the wafer's surface quality.
Implementation Method 1
a wafer mirror surface beveling method that mirror polishes a chamfered surface of a wafer with a polishing pad
Implementation Method 2
a stage configured to attach the wafer by adhesion and that rotates while holding the wafer
Data Source
AI summary
Example features relate to a method of polishing a chamfered wafer surface, the method including beveling a wafer to generate the chamfered wafer surface, the chamfered wafer surface being inclined with respect to a main wafer surface by an angle θ; and polishing the chamfered wafer surface with a polishing pad, a polishing surface of the polishing pad being inclined with respect to the chamfered wafer surface by an angle α; wherein the angle α is equal to or smaller than the angle θ. Example features relate to a system for polishing the chamfered surface, the system including a polishing pad mounting jig configured to polish the chamfered surface, an angle θ being defined between the chamfered surface and the main surface; and a polishing pad in contact with the chamfered surface at an angle α during polishing; wherein the angle α is smaller than the angle θ.