Infrared Vision Die Bonding Alignment
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Solution Overview
Problem
Existing die bonding methods face challenges with motion errors during die pick-up and limited accuracy in alignment due to adhesion and rotation issues, and conventional inspection methods are unreliable for post-bonding quality checks, especially for under-fill glue and silver epoxy, as they require complex calibration and off-line equipment.
Innovation Solution
The use of an infrared vision system to align and inspect semiconductor dies by projecting infrared light through the die and capturing images of the reflected light from the circuit pattern, allowing for accurate alignment and post-bond inspection of alignment and coverage of materials like silver epoxy and under-fill glue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical systems are used to capture images of the die for alignment, then the alignment process can be performed, but motion error occurs during the die pick-up process after the image is captured and cannot be corrected
Solution Approach 1:
The patent performs alignment imaging after the die has been picked up by the pick head, rather than before. This preliminary action of imaging post-pickup allows the system to capture the die's actual position and orientation after it has been lifted from the wafer, thereby identifying and correcting motion errors that occurred during the pick-up process.
Solution Approach 2:
The patent implements a feedback mechanism where the optical system captures images of the die after pick-up, compares the captured position with the intended position, and adjusts the pick head's position accordingly. This closed-loop feedback ensures that motion errors are detected and corrected, improving both alignment accuracy and reliability.
2Productivity
If the die is lifted from adhesive Mylar paper, then the die can be picked up, but an unexpected die offset or rotation relative to the pick head may arise when the die leaves the film surface
Solution Approach 1:
The patent performs position imaging after the die has been picked up from the Mylar paper, allowing the system to detect any offset or rotation that occurred during the pick-up process. This preliminary imaging action enables real-time correction of position errors before the die is placed on the substrate.
Solution Approach 2:
The optical system provides feedback on the die's actual position and orientation after pick-up, allowing the control system to compensate for any offset or rotation that occurred during the lifting process from the Mylar paper, thereby maintaining manufacturing precision.
3Ease of manufacture
If alignment is performed based on the die boundary, then alignment can be achieved, but accuracy is subject to sawing quality and conditions of the bottom side of the die which may not be sufficiently straight
Solution Approach 1:
The patent uses optical imaging to create a digital copy or representation of the die's position and orientation after pick-up. This optical copy allows for precise measurement and correction of alignment errors without being affected by the physical limitations of the die boundary or sawing quality.
Solution Approach 2:
The patent replaces mechanical alignment methods (which rely on physical contact and visual inspection of the die boundary) with an optical imaging system. This substitution allows for non-contact, high-precision measurement of the die's position and orientation, eliminating the limitations imposed by poor cutting quality or uneven edges.
4Productivity
If conventional inspection methods are used for post-bonding quality checks, then inspection can be performed, but complex calibration and off-line equipment are required and reliability is limited
Solution Approach 1:
The patent merges the alignment optical system with the inspection function, allowing the same optical system to be used for both pre-bond alignment and post-bond inspection. This integration eliminates the need for separate inspection equipment and complex calibration procedures, while maintaining high reliability through consistent optical measurement.
Solution Approach 2:
The optical system creates digital images of the die and substrate for both alignment and inspection purposes. These optical copies allow for automated analysis of bonding quality, including detection of misalignment, voids, and other defects, without requiring physical contact or complex off-line equipment.
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 method improves the accuracy of die alignment and post-bond inspection by enabling online, direct visualization of hidden patterns, reducing motion errors and enhancing the reliability of bonding quality checks, and allowing for precise determination of material coverage and voids.
Implementation Method 1
projecting infrared light from the infrared light source onto a second side of the die opposite to the first side such that the infrared light passes through a body of the die
Implementation Method 2
detecting and capturing an image of the infrared light reflected from the circuit pattern
Data Source
AI summary
A method of aligning a die when the die is held with a circuit pattern on a first side of the die facing away from an infrared light source, wherein infrared light from the infrared light source is projected onto a second side of the die opposite to the first side such that the infrared light passes through a body of the die. From the second side of the die, an image of the infrared light reflected from the circuit pattern is detected and captured. Thereafter, an alignment of the die from the captured image of the die is determined.