Semiconductor Die Bond Inspection Using Infrared Thermal Imaging
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Solution Overview
Problem
Current defect inspection methods for semiconductor packages, such as scanning acoustic tomography, are limited in detecting voids during the hybrid bonding process due to the need for a liquid medium, which can introduce additional voids and require post-stacking inspection, reducing process yield and inspection speed.
Innovation Solution
A defect inspection apparatus using a stage, heater, and thermal imaging camera to apply localized heat and measure temperature changes on the bonding interface of semiconductor dies, allowing in-situ inspection of voids without a separate medium, enabling real-time monitoring during the bonding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If scanning acoustic tomography (SAT) is used to inspect voids at bonding interfaces, then void detection capability is provided, but additional voids are introduced due to water adsorption on die surfaces after testing
Solution Approach 1:
The patent extracts and eliminates the liquid medium requirement from the inspection process by using infrared thermal imaging instead of acoustic waves. This removes the harmful water adsorption effect while maintaining void detection capability through thermal contrast differences caused by voids at bonding interfaces.
Solution Approach 2:
The patent replaces the mechanical/acoustic inspection system (SAT requiring liquid coupling) with a thermal-optical system (infrared imaging). This substitution eliminates the need for liquid media and water adsorption issues while providing non-contact void detection through thermal field analysis.
2Measurement precision
If SAT inspection is performed after semiconductor die stacking is completed, then void inspection is possible, but inspection speed is reduced and process yield deteriorates
Solution Approach 1:
The patent performs void inspection at each bonding step immediately after die stacking rather than after complete assembly. This preliminary inspection approach enables real-time defect detection and early rejection of defective stacks, preventing waste of subsequent processing steps and improving overall process yield.
Solution Approach 2:
The patent implements continuous inspection throughout the bonding process by integrating thermal imaging at each stacking step. This continuous monitoring maintains high inspection speed and enables real-time process control, unlike post-assembly inspection which creates bottlenecks and reduces productivity.
3Measurement precision
If liquid medium is used for void inspection, then void detection is enabled, but semiconductor dies deteriorate due to exposure to liquid
Solution Approach 1:
The patent replaces liquid-based acoustic inspection with contactless infrared thermal imaging. This eliminates all harmful effects of liquid exposure on semiconductor dies while maintaining effective void detection through thermal field analysis, as infrared waves can penetrate and detect thermal contrasts without physical contact.
Solution Approach 2:
The patent uses infrared radiation as an intermediary between the inspection system and the semiconductor dies. This intermediary enables void detection through thermal field analysis without requiring direct liquid contact with the dies, thus preventing deterioration while maintaining inspection effectiveness.
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 prevents semiconductor die deterioration, improves inspection speed, and enhances process yield by allowing real-time defect detection during each bonding step, applicable to both die-to-wafer and wafer-to-wafer bonding processes.
Implementation Method 1
a heater configured to apply heat to a surface of the second semiconductor die on the stage, which is opposite to a bonding interface of the first semiconductor die and the second semiconductor die
Implementation Method 2
a camera configured to measure a temperature change on the surface of the second semiconductor die to which the heat is applied to check a state of the bonding interface
Data Source
AI summary
Provided is a method of manufacturing a semiconductor package, the method including: providing a first semiconductor die on a stage; bonding a second semiconductor die to the first semiconductor die to each other; applying heat to a surface of the second semiconductor die, which is opposite to a bonding interface of the first semiconductor die and the second semiconductor die; and measuring a temperature change on the surface of the second semiconductor die to which the heat is applied to inspect a state of the bonding interface.