Helical Silicon Wafer Chamfering for Small Taper Angle Control
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Solution Overview
Problem
The existing helical chamfer machining methods for silicon wafers struggle to consistently achieve a small finished wafer taper angle, leading to reduced chamfering wheel life and increased production costs due to frequent wheel replacements, as the groove bottom diameter of the chamfering wheel affects the achievable taper angle.
Innovation Solution
A method involving successive helical chamfer machining with different truer taper angles based on the groove bottom diameter of the chamfering wheel, including a first truing step with a first truer taper angle, determining the groove bottom diameter, a second truing step with a second truer taper angle when necessary, and adjusting the groove bottom diameter to maintain the target wafer taper angle within an allowable range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single truer taper angle is used for helical chamfer machining, then the machining process is simple, but the finished wafer taper angle cannot be maintained within the allowable range as the groove bottom diameter changes
Solution Approach 1:
The patent applies parameter changes by switching between different truer taper angles (first truer taper angle and second truer taper angle) depending on the groove bottom diameter of the chamfering wheel. When the groove bottom diameter is large, a first truer taper angle is used; when it becomes small, a second truer taper angle is used. This dynamic parameter adjustment ensures the finished wafer taper angle remains within the allowable range throughout the wheel's lifespan.
2Manufacturing precision
If the groove bottom diameter of the chamfering wheel decreases, then the finished wafer taper angle deviates from the target value, but replacing the wheel frequently increases production costs
Solution Approach 1:
The patent implements dynamics by making the truing process adaptive to the changing groove bottom diameter. Instead of using a fixed truer taper angle, the system dynamically selects between a first truer taper angle (for larger groove bottom diameters) and a second truer taper angle (for smaller groove bottom diameters). This dynamic adjustment extends the usable life of the chamfering wheel while maintaining precision.
3Manufacturing precision
If a first truer taper angle is used when the groove bottom diameter is large, then the initial wafer taper angle can be controlled, but the taper angle drifts as the wheel wears down
Solution Approach 1:
The patent employs feedback by monitoring the groove bottom diameter of the chamfering wheel and adjusting the truer taper angle accordingly. The system determines whether to use the first or second truer taper angle based on the current groove bottom diameter, creating a feedback loop that maintains wafer taper angle consistency throughout the wheel's operational life.
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 extends the number of machining operations possible with a single chamfering wheel, reducing the need for frequent replacements and lowering production costs while maintaining the desired small finished wafer taper angle.
Implementation Method 1
The fine grinding grindstone portion 10B is pressed against the silicon wafer W being rotated thereby performing finish chamfer machining
Implementation Method 2
the groove portion in the fine grinding grindstone portion 10B of the chamfering wheel 10 is machined by pressing and rotating the truer and the chamfering wheel 10 against each other
Data Source
AI summary
Provided is a method of chamfer machining a silicon wafer which makes it possible to increase the number of machining operations that can be performed using a chamfering wheel used for helical chamfer machining in the case of obtaining a small finished wafer taper angle. The method in which helical chamfer machining is performed so that the finished wafer taper angle θ of an edge portion in the one silicon wafer is within an allowable angle range of a target wafer taper angle θ0 includes a first truing step; a first chamfer machining step; a step of determining a groove bottom diameter ϕA of the fine grinding grindstone portion; a second truing step using a second truer taper angle α2; and a second chamfer machining step. The second truer taper angle α2 is made larger than the first truer taper angle α1.