Substrate Warpage Estimation Using Radial Pixel-Value Change
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Solution Overview
Problem
Existing methods for estimating warpage in substrates with large warpage amounts require larger apparatus sizes due to the need for moving mechanisms or expanded imaging fields, which increases the overall size of the equipment.
Innovation Solution
A warpage amount estimation apparatus and method that uses a camera system to capture images of the substrate's surface, calculates the rate of change in pixel values along the radial direction, and estimates warpage based on pre-established correlations between pixel value changes and warpage amounts without requiring increased apparatus size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a moving mechanism or expanded imaging field is used to estimate warpage in substrates with large warpage amounts, then measurement precision is improved, but device complexity and apparatus size increase
Solution Approach 1:
The patent replaces mechanical moving mechanisms with an optical imaging system that captures the entire substrate surface in a single static image. The camera system with appropriate lens focal length and aperture is positioned to image the complete substrate including peripheral edges, eliminating the need for mechanical movement while maintaining measurement capability for large warpage amounts.
Solution Approach 2:
The patent transitions from mechanical displacement in one dimension (moving the imaging system) to optical field expansion in multiple dimensions (using appropriate focal length and aperture to capture the entire substrate surface in a single image). This dimensional approach allows the entire substrate to be imaged without mechanical movement, solving the contradiction between measurement precision and apparatus size.
2Measurement precision
If the imaging field is expanded to capture the entire substrate surface, then measurement precision is improved, but the apparatus size increases
Solution Approach 1:
The patent changes optical parameters (focal length, aperture, imaging distance) to achieve the desired imaging field coverage. By selecting appropriate optical parameters, the system can capture the entire substrate surface including peripheral edges without physically expanding the apparatus structure, thus maintaining compact size while achieving complete surface imaging for accurate warpage measurement.
Data Source
AI summary
A warpage amount estimation apparatus that estimates a warpage amount of a substrate includes a processor and a memory. The processor acquires a captured image of one surface of an estimation target substrate. The processor calculates a rate of change in pixel value relating to a substrate radial direction in the captured image of the one surface of the estimation target substrate. The processor estimates a warpage amount of the estimation target substrate based on a correlation obtained in advance between a rate of change in pixel value relating to the substrate radial direction in a captured image of the one surface of a substrate and a warpage amount of the substrate, and on a calculation result of the rate of change which is calculated.