Double-Side Polishing Torque Control for Wafer Flatness
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Solution Overview
Problem
Existing double-side polishing methods for wafers, such as those described in PTL 1, are limited in improving polishing precision and wafer flatness, and do not allow for precise control of the work thickness during the polishing process.
Innovation Solution
A method and apparatus for double-side polishing that utilize a sun gear and internal gear system to measure and control the torques applied to the work, allowing for precise adjustment of polishing conditions based on the target shape of the work, as indicated by GBIR and ESFQR values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the rotation ratio of the carrier plate is controlled to avoid reduction in polishing precision, then the polishing precision is maintained, but the improvement in polishing precision is limited
Solution Approach 1:
The patent implements a feedback control system that measures the actual shape of the workpiece after polishing and compares it with the target shape. Based on this comparison, the system automatically adjusts the rotation ratio of the carrier plate and other polishing parameters to achieve the desired GBIR and ESFQR values, enabling continuous improvement of polishing precision beyond fixed control methods
Solution Approach 2:
The patent systematically varies multiple polishing parameters including the rotation ratio of the carrier plate, rotation speed of the polishing apparatus, and polishing pressure to optimize the polishing outcome. By changing these parameters dynamically based on feedback, the system achieves both high polishing precision and improved adaptability
2Ease of operation
If polishing is performed with fixed rotation conditions to maintain simple operation, then the operation is easy, but the control of work thickness and flatness is imprecise
Solution Approach 1:
The patent employs a self-service control mechanism where the system automatically measures the workpiece shape after polishing and adjusts the rotation ratio without requiring manual intervention. The control unit autonomously processes measurement data, determines optimal rotation ratios, and executes the adjustments, maintaining ease of operation while achieving precise thickness and flatness control
Solution Approach 2:
The patent replaces manual adjustment of polishing parameters with an automated control system that uses sensors and computing units to measure and adjust the rotation ratio. This substitution of mechanical/manual control with automated electronic control enables precise thickness and flatness control while maintaining operational simplicity
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 enables precise control of the work thickness and improves the flatness of the work, achieving higher polishing precision and flatness compared to existing methods.
Implementation Method 1
measuring a torque of the sun gear (Ti) and a torque of the internal gear (To)
Data Source
AI summary
The sum of torques: the torque of the sun gear and the torque of the internal gear, and the ratio of the torques are controlled within predetermined ranges.