Laser-Assisted Bonding Beam Alignment Using Vision Calibration
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Solution Overview
Problem
Existing methods for die-beam alignment in laser-assisted bonding are prone to human error and lack a defined metric for quantitative evaluation, leading to misalignment issues that can damage semiconductor devices.
Innovation Solution
A method involving vision alignment followed by the generation of calibration equations using image-acquisition cameras and computer algorithms to accurately align the laser beam with the semiconductor die, ensuring precise X-Y positional and rotational alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If human visual inspection is used for die-beam alignment, then the alignment process is simple and quick, but the alignment precision is low and prone to human error
Solution Approach 1:
The patent replaces the mechanical human visual inspection system with an automated optical measurement system. Image-acquisition cameras capture images of the die and beam positions, and computer algorithms automatically calculate alignment metrics, substituting human eyes and judgment with mechanical-optical-electronic systems that provide quantitative, objective measurements.
Solution Approach 2:
The patent creates visual copies (images) of the physical die and laser beam positions using image-acquisition cameras. These images serve as digital representations that can be analyzed by computer algorithms to determine alignment, allowing the system to measure and evaluate alignment without direct human observation of the physical objects.
2Manufacturing precision
If automated vision alignment with calibration equations is implemented, then the alignment precision is improved, but the device complexity increases
Solution Approach 1:
The patent performs preliminary actions by pre-calculating calibration equations that relate camera image coordinates to the actual physical positions of the die and beam. These calibration equations are established before production alignment measurements, creating a reference framework that simplifies subsequent alignment operations and enables precise, automated measurements.
Solution Approach 2:
The patent implements feedback by using computer algorithms to automatically calculate alignment metrics from captured images and provide quantitative evaluation of the die-beam alignment status. This feedback mechanism allows the system to objectively assess alignment quality and guide adjustments, replacing subjective human judgment with automated measurement and evaluation.
3Reliability
If misalignment occurs in laser-assisted bonding, then the process speed is maintained, but the reliability of the bonding process deteriorates due to damaged semiconductor devices
Solution Approach 1:
The patent performs preliminary alignment verification using image-acquisition cameras and computer algorithms before the laser bonding process begins. By calculating alignment metrics in advance and confirming proper alignment, the system ensures that the subsequent bonding operation will be reliable and avoid device damage, preventing rework and maintaining overall productivity.
Solution Approach 2:
The patent replaces manual alignment verification with automated optical measurement and computer-based analysis. Image-acquisition cameras capture precise positional information, and algorithms automatically evaluate alignment quality, providing objective, quantitative assessment that ensures bonding reliability without the variability and error-prone nature of human visual inspection.
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
Ensures precise alignment of the laser beam with the semiconductor die, reducing manufacturing defects and containing thermal energy to the intended areas, thereby improving the reliability and efficiency of the bonding process.
Implementation Method 1
image-acquisition cameras and computer algorithms to accurately align the laser beam with the semiconductor die
Implementation Method 2
LAB uses a laser to apply energy directly to the back side of the die being mounted, which is converted to thermal energy to reflow solder bumps on the front side of the die
Implementation Method 3
energy directly to the back side of the die being mounted, which is converted to thermal energy
Data Source
AI summary
A method of making a semiconductor device involves the steps of disposing a first semiconductor die over a substrate and disposing a beam homogenizer over the first semiconductor die. A beam from the beam homogenizer impacts the first semiconductor die. The method further includes the steps of determining a positional offset of the beam relative to the first semiconductor die in a number of pixels, using a first calibration equation to convert the number of pixels into a distance in millimeters, and moving the beam homogenizer the distance in millimeters to align the beam and first semiconductor die.