Non-Contact Optical Warpage Measurement for IC Chips
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Solution Overview
Problem
Current methods for measuring warpage and coefficient of thermal expansion (CTE) in IC chips, especially above the glass transition temperature, are inefficient and prone to measurement errors due to their contact-based nature, which is challenging for soft materials and affects chip reliability.
Innovation Solution
A non-contact optical method using image capture and analysis processing with a pair of cameras, combined with a controlled temperature changing module, to measure surface flatness and CTE by projecting light patterns onto the specimen and capturing images before and after temperature changes, allowing for accurate strain determination and CTE calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If contact-based methods are used to measure warpage and CTE, then measurement can be performed on hard materials, but measurement errors increase and reliability decreases for soft materials above glass transition temperature
Solution Approach 1:
The patent replaces contact-based mechanical measurement methods with a non-contact optical measurement system. The system uses a pair of cameras to capture images of the specimen surface, and through image processing and analysis, measures warpage and CTE without physical contact. This eliminates the measurement errors and reliability issues associated with contact-based methods on soft materials above glass transition temperature.
Solution Approach 2:
The patent changes the measurement approach from mechanical contact to optical non-contact measurement. By using optical parameters (light reflection, image coordinates) instead of mechanical parameters (physical contact force, displacement), the system achieves accurate measurement of soft materials without affecting their structural integrity or measurement reliability.
2Measurement precision
If non-contact optical method is used, then measurement accuracy for soft materials improves, but system complexity increases due to calibration and temperature control requirements
Solution Approach 1:
The patent implements a calibration process before actual measurement to establish the relationship between image coordinates and physical dimensions. The calibration means pre-configures the measurement system by capturing images of known reference objects and calculating calibration parameters, which are then used to convert measurement images into accurate warpage data. This preliminary action simplifies the actual measurement process.
Solution Approach 2:
The patent introduces a calibration means as an intermediary between the camera system and the measurement process. The calibration means includes reference objects with known dimensions that mediate the conversion from optical images to precise physical measurements. This intermediary component standardizes the measurement process and reduces system complexity by providing a consistent reference framework.
3Measurement precision
If temperature control is implemented to measure CTE, then accurate thermal expansion measurement is achieved, but measurement time and energy consumption increase
Solution Approach 1:
The patent implements continuous temperature control and continuous image capture during the heating/cooling process. The temperature control means maintains a steady temperature profile while the image capture means continuously records the specimen's dimensional changes. This continuous measurement approach eliminates the need for multiple discrete measurements and allows for real-time CTE calculation, reducing total measurement time.
Solution Approach 2:
The patent uses feedback control in the temperature management system. The temperature control means monitors the specimen's temperature in real-time and adjusts heating/cooling rates to maintain optimal measurement conditions. This feedback mechanism ensures accurate CTE measurement by compensating for thermal gradients and measurement timing variations, while optimizing the measurement process to reduce unnecessary time delays.
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 provides accurate, high-resolution, and cost-effective measurements of warpage and CTE, reducing measurement errors and improving chip reliability by eliminating the need for contact-based methods, especially for soft materials above their glass transition temperature.
Implementation Method 1
projecting light from a light source module to said test specimen with a designed pattern, or to said test specimen printed with a designed pattern
Implementation Method 2
determine strain arising from (T−T1), generating strain c versus temperature plot, and determining surface flatness
Data Source
AI summary
The present invention is directed to a system for measuring surface flatness, deformation and/or coefficient of thermal expansion (CTE) of a specimen comprising an image capture and analysis processing calibration means for performing image capture and analysis processing calibration of said system, a measuring means for measuring surface flatness of a specimen in a specimen holder, a heating means for heating said sample holder with a predetermined profile, and a control means for providing the predetermined heating profile onto the surface of said specimen and controlling operations of said image capture and analysis processing calibration means, said measuring means, and said heating means.