Grinding Apparatus Thickness Measurement and Tilt Adjustment
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Solution Overview
Problem
Existing grinding apparatuses face inefficiencies in measuring the thickness distribution of workpieces being ground and adjusting the tilt of the table rotational axis accurately, leading to irregularities and waste in semiconductor wafer processing.
Innovation Solution
A grinding apparatus with a thickness measuring device that moves back and forth on a measuring track, allowing for continuous measurement of thicknesses while avoiding interference with the grinding unit, and a control unit that calculates average thickness values and cross-sectional shapes to adjust the tilt of the table rotational axis using a cross-sectional shape interpolating section via the least-squares method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the measuring unit moves over the workpiece while grinding to measure thickness continuously, then measurement precision is improved, but the measuring unit cannot access the central portion of the workpiece due to interference with the grinding unit
Solution Approach 1:
The measurement process is segmented into multiple passes. The measuring unit measures the workpiece in sections during grinding, avoiding the central portion during each pass, and combines these measurements to reconstruct the complete thickness distribution including the central area.
Solution Approach 2:
The system performs preliminary measurements of the workpiece thickness at multiple locations before completing the grinding process. These preliminary measurements are used to calculate the cross-sectional shape and predict the central portion thickness, enabling tilt adjustment during the grinding process.
2Manufacturing precision
If the grinding process is temporarily stopped to measure thickness and adjust tilt, then manufacturing precision is improved, but productivity deteriorates
Solution Approach 1:
The grinding process continues without interruption while the measuring unit moves across the workpiece surface. The system performs measurements and calculates tilt adjustments in real-time during the grinding operation, eliminating the need to stop the process for quality checks and adjustments.
Solution Approach 2:
The system implements continuous feedback by measuring workpiece thickness during grinding, calculating the cross-sectional shape and required tilt adjustment, and applying the tilt adjustment dynamically. This closed-loop control ensures thickness uniformity while maintaining continuous production flow.
3Measurement precision
If multiple data maps are stored and cross-sectional shape is calculated to predict central portion thickness, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The system creates a digital copy (data map) of the workpiece cross-sectional shape based on measurements from accessible areas. This digital model is then used to predict the thickness at the central portion without direct measurement, reducing the need for complex physical measurement systems while maintaining prediction accuracy.
Solution Approach 2:
The patent replaces direct physical measurement of the central portion with a computational model. Instead of using complex mechanical measurement systems to access the central area, the system uses mathematical calculations based on measured data and stored cross-sectional shape patterns to predict the unmeasured central region thickness.
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
Enables precise and continuous measurement of workpiece thickness distribution, allowing for accurate adjustment of the table rotational axis tilt, thereby improving processing efficiency and reducing waste by ensuring uniform thickness across the workpiece.
Implementation Method 1
a thickness measuring device for measuring a thickness of the workpiece held on the chuck table
Implementation Method 2
the grindstones into contact with the workpiece on the chuck table while the chuck table and the grinding wheel are rotating, the grindstones grind the workpiece
Implementation Method 3
bring the grindstones into abrasive contact with the upper surface of the workpiece and thereby grind the workpiece
Data Source
AI summary
A grinding apparatus includes a chuck table, a grinding unit, a thickness measuring device for measuring a thickness of the workpiece, and a control unit. The thickness measuring device includes a measuring unit for measuring the thickness of the workpiece and a measuring unit moving mechanism for moving the measuring unit back and forth on a measuring track. The control unit controls the measuring unit to measure thicknesses of the workpiece at various points thereon while moving the measuring unit back and forth on the measuring track, calculates a cross-sectional shape of the workpiece from average values of thickness values measured by the measuring unit in a forward stroke on the measuring track and thickness values measured by the measuring unit in a return stroke on the measuring track, and calculates a tilt adjustment variable for a table rotational axis according to the calculated cross-sectional shape.