Wafer Thickness Measurement Through a Notched Substrate Holder
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Solution Overview
Problem
Existing wafer processing systems cannot accurately measure the thickness of both the upper and lower wafers in a combined wafer, leading to potential deterioration of flatness due to relative inclination between the grinding whetstone and the chuck during thinning of the upper wafer.
Innovation Solution
A wafer processing system with a substrate holder, measurer, and moving mechanism that allows for measuring the thickness of both the upper and lower wafers by using a partial thickness measurer and total thickness measurer, respectively, and adjusting the relative inclination between the chuck and grinding wheel based on these measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a combined wafer is processed without accurate thickness measurement of both upper and lower wafers, then the processing can proceed, but the flatness of the upper wafer deteriorates due to relative inclination between grinding whetstone and chuck
Solution Approach 1:
The thickness measurement function is segmented into two independent measurement systems: a first thickness measurer for measuring the upper wafer and a second thickness measurer for measuring the lower wafer. This segmentation allows each measurer to be optimized for its specific measurement task, with the first measurer positioned to access the upper wafer surface and the second measurer positioned to access the lower wafer surface through the substrate holder structure.
Solution Approach 2:
The substrate holder serves as an intermediary structure that not only holds the combined wafer but also provides a mounting platform for the second thickness measurer. The substrate holder mediates between the lower wafer measurement requirement and the grinding system, enabling the second measurer to measure the lower wafer thickness without interfering with the upper wafer processing.
2Measurement precision
If the substrate holder structure is modified to enable lower wafer measurement, then thickness measurement capability is improved, but the device complexity increases
Solution Approach 1:
The substrate holder is designed with multi-functionality: it serves as the mounting structure for holding the combined wafer during grinding, provides structural support for the first thickness measurer, and accommodates the second thickness measurer for lower wafer measurement. By making the substrate holder universal, the patent avoids adding separate dedicated structures for each function, thereby reducing overall device complexity while maintaining enhanced measurement capability.
Solution Approach 2:
The patent merges the substrate holder structure with the measurement system mounting structure. Instead of having separate independent structures for holding substrates and mounting measurers, the substrate holder is designed to integrate both functions, with mounting positions for both thickness measurers built into the holder structure itself.
Data Source
AI summary
A thickness measuring device configured to measure a thickness of a substrate includes a substrate holder configured to hold the substrate; a measurer configured to measure the thickness of the substrate held by the substrate holder; and a moving mechanism configured to move the substrate holder and the measurer relatively in a horizontal direction. The substrate holder is provided with a notch portion which extends in a diametrical direction from a center of the substrate holder to an outer end thereof, and the measurer is configured to be relatively advanced into or retreated from the notch portion.