Substrate Inspection Height Adjustment Using Warpage Tendency
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Solution Overview
Problem
Existing substrate inspection methods face challenges with warpage-induced height deviations, leading to reduced inspection accuracy and increased time, especially when large substrates are inspected, as they require frequent adjustments and the use of laser range finders to maintain focus.
Innovation Solution
The method involves adjusting the height of the inspecting module based on height tendency information from previous inspection regions, using multi-wavelength patterned lights, and setting dummy inspection regions to enhance accuracy and range, while also accounting for substrate transfer-induced height displacements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the substrate is inspected by fixing both end portions and supporting them, then the substrate can be stably held, but height deviation among inspection regions occurs due to warpage
Solution Approach 1:
The system dynamically changes the Z-axis position parameter of the inspecting module based on measured height deviations. By adjusting the Z-axis position according to the warpage profile, the inspection system compensates for height deviations and maintains proper focus across different regions of the substrate.
2Measurement precision
If the height deviation is measured by laser range finder and inspecting module height is adjusted, then inspection accuracy is maintained, but inspection time increases
Solution Approach 1:
The system performs preliminary measurement of the substrate's height profile using a laser range finder before the actual inspection process. This preliminary action allows the system to pre-calculate and store the warpage profile, enabling rapid Z-axis position adjustments during inspection without time-consuming real-time measurements.
Solution Approach 2:
The system creates a digital copy or model of the substrate's height profile through preliminary laser scanning. This height profile data is then used as a reference map during inspection, allowing the system to quickly adjust to different heights without physically re-measuring the substrate during the inspection process.
3Length of stationary object
If multi-wavelength patterned lights are used, then height inspection range is increased, but device complexity increases
Solution Approach 1:
The system merges multiple light sources with different wavelengths into a single inspection system. By combining blue, green, and red light sources, the system can simultaneously or sequentially illuminate the substrate with different wavelengths, enabling height measurement across a broader range while sharing common optical components and control mechanisms.
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 reduces inspection time, increases the inspection range, and enhances accuracy by leveraging height tendency information and multi-wavelength lighting, thereby improving the reliability of substrate inspections even with severe warpage.
Implementation Method 1
a light source and a grid pattern for projecting patterned light
Implementation Method 2
the inspecting module includes a camera for capturing an image formed by the patterned light when the patterned light is reflected by a target object
Implementation Method 3
the height deviation among the inspection region is firstly measured by a laser range finder
Data Source
AI summary
A method of inspecting a substrate is disclosed. The method is performed by a substrate-inspecting apparatus having at least one projecting module projecting a patterned light onto a substrate fixed on a stage and an inspecting module with a camera capturing an image, and inspecting a plurality of inspection regions of the substrate step by step. The method comprises, setting an inspection order of the inspecting regions according to a lengthwise direction of the substrate, estimating height displacement of a target inspection region by using a tendency information regarding at least one previous inspection region that is already inspected, adjusting height of the inspecting module by using the estimated height displacement of the target inspection region, and inspecting the target inspection region by using the inspecting module of which height is adjusted. Therefore, inspection time is reduced.