Semiconductor Package Multi-Shot Laser Reflow for Bonding Consistency
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Solution Overview
Problem
The challenge in semiconductor packaging is to reduce wafer warpage and improve integration density while maintaining consistent bonding quality, particularly in Package-on-Package (PoP) technology, where indirect heating can cause warping and affect the integrity of the connection between stacked semiconductor packages.
Innovation Solution
A multi-shot reflow process using a laser beam to selectively heat and reflow conductive connectors on the top package component, minimizing indirect heating of the bottom component, which reduces warpage and ensures consistent bonding by varying laser shot parameters to control heating and cooling effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If indirect heating is used to reflow conductive connectors, then bonding between package components is achieved, but wafer warpage increases and bonding consistency deteriorates
Solution Approach 1:
The patent applies local quality by using a laser beam to selectively heat only the conductive connectors and immediate surrounding areas, rather than heating the entire wafer surface. This localized heating approach melts the conductive connectors for bonding while minimizing thermal diffusion to the bulk wafer, thereby reducing wafer warpage and improving bonding consistency.
Solution Approach 2:
The patent segments the heating process into multiple discrete laser shots rather than continuous heating. The laser beam is moved to different locations to reflow conductive connectors at separate positions, allowing controlled thermal processing of individual bonding areas. This segmentation prevents cumulative thermal buildup that would cause warpage while ensuring each bonding interface receives adequate heat.
2Manufacturing precision
If laser beam parameters are kept constant for all shots, then process simplicity is maintained, but heating uniformity and bonding quality across different regions deteriorate
Solution Approach 1:
The patent implements dynamics by making laser shot parameters variable rather than fixed. The system dynamically adjusts laser shot parameters such as energy, duration, or frequency based on the specific location and characteristics of each conductive connector. This adaptive approach ensures uniform heating and consistent bonding quality across different regions of the wafer, with more complex control logic managing the parameter variations.
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
The multi-shot reflow process reduces wafer warpage and enhances bonding consistency, minimizing defects like cold joints and solder bridging, while allowing for more flexible manufacturing and increased throughput.
Implementation Method 1
performing a multi-shot reflow process using a laser beam to selectively heat and reflow conductive connectors on the top package component
Implementation Method 2
minimizing indirect heating of the bottom component, which reduces warpage
Implementation Method 3
reflowing the conductive material of the first package component and the conductive material of the second package component to bond the first package component to the second package component
Data Source
AI summary
In an embodiment, a method includes: aligning a first package component with a second package component, the first package component having a first region and a second region, the first region including a first conductive connector, the second region including a second conductive connector; performing a first laser shot on a first portion of a top surface of the first package component, the first laser shot reflowing the first conductive connector of the first region, the first portion of the top surface of the first package component completely overlapping the first region; and after performing the first laser shot, performing a second laser shot on a second portion of the top surface of the first package component, the second laser shot reflowing the second conductive connector of the second region, the second portion of the top surface of the first package component completely overlapping the second region.