Wafer Beveled Edge Contour Measurement Using Shadow and Optical Profiles
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Solution Overview
Problem
Existing contour shape measuring devices struggle to accurately measure the shape of disk-shaped objects with beveled peripheral edges due to edge thinning and light scattering, leading to potential wafer cracking and measurement inaccuracies.
Innovation Solution
A contour shape measuring device that combines a shadow contour shape measuring unit and an optical contour shape measuring unit, using optical cutting and confocal methods to measure the contour shape from different directions, and a contour shape calculating unit to integrate the results, with noise removal based on height variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If light is applied to measure the contour shape of a trimmed wafer, then the measurement can be performed, but the shape of the stepped portion becomes blurred due to light scattering and measurement accuracy deteriorates
Solution Approach 1:
The measurement is divided into two independent parts: shadow contour shape measurement (side view) and optical contour shape measurement (top view). Each measurement method uses lighting and detection angles optimized for its specific purpose, avoiding the light scattering problem that affects single-method measurements of stepped portions.
Solution Approach 2:
The invention transitions from single-dimension measurement to multi-dimensional measurement by combining side-view shadow imaging with top-view optical imaging. This dimensional approach allows each measurement to capture different aspects of the contour shape, with the stepped portion clearly visible in the shadow measurement and the overall shape captured in the optical measurement.
2Measurement precision
If a single measurement method is used, then the device complexity is low, but the measurement accuracy of contour shapes with beveled edges deteriorates
Solution Approach 1:
The invention merges two different measurement methods (shadow contour shape measurement and optical contour shape measurement) into a single integrated system. The contour shape calculation unit combines results from both measurement units, leveraging the strengths of each method to achieve high overall measurement accuracy.
Solution Approach 2:
The measurement system is designed to perform multiple functions: the shadow contour shape measuring unit captures side-view profiles, the optical contour shape measuring unit captures top-view shapes, and the contour shape calculation unit integrates both to produce the final contour shape data. This multi-functional approach allows accurate measurement of various contour features including stepped portions and beveled edges.
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 device achieves higher accuracy in measuring contour shapes by integrating shadow and optical contour shapes, effectively reducing noise and enhancing measurement precision.
Implementation Method 1
a shadow contour shape measuring unit that measures the contour shape as a shadow contour shape on a basis of a shadow image obtained by imaging a shadow of the peripheral edge portion generated by applying light onto the peripheral edge portion from a tangential direction of an outer periphery
Implementation Method 2
an optical contour shape measuring unit that measures the contour shape of the peripheral edge portion as an optical contour shape by measuring a distance to the measurement target object using light from a surface direction
Data Source
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AI summary
The present invention relates to a contour shape measuring device and a method for measuring a contour shape in a disk-shaped measurement target object having a beveled peripheral edge portion, in which the contour shape is measured as a shadow contour shape on the basis of a shadow image obtained by imaging a shadow of the peripheral edge portion generated by applying light onto the peripheral edge portion from a tangential direction of an outer periphery, the contour shape of the peripheral edge portion is measured as an optical contour shape by measuring a distance to the measurement target object using light from a surface direction, and the contour shape is obtained on the basis of the shadow contour shape and the optical contour shape.