IC Package Laser Drilling Sequence to Limit Heat Buildup
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Solution Overview
Problem
The challenge in semiconductor packaging lies in efficiently forming openings in insulating layers to expose pads while minimizing heat accumulation, dendrite formation, and delamination, particularly in stacked integrated fan-out packages with limited space for through vias.
Innovation Solution
A laser drilling process is employed to form openings in the insulating layers of redistribution structures, with controlled laser shots on overlapping locations to reduce the number of shots and minimize heat accumulation, thereby reducing dendrite formation and delamination, and increasing wafer-per-hour yield and reliability analysis pass rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple laser shots are performed on the same location to form openings in insulating layers, then the openings are successfully formed, but heat accumulation increases causing dendrite formation and delamination
Solution Approach 1:
The patent divides the laser drilling process into multiple sequential laser shots performed at different locations rather than concentrating multiple shots on the same location. This segmentation of the drilling approach distributes the thermal load across different areas, preventing heat accumulation at any single point while still achieving complete opening formation through the insulating layers.
Solution Approach 2:
The patent transitions from a single-location multi-shot approach to a multi-location single-shot approach, effectively changing the spatial dimension of the drilling strategy. By performing laser shots at different locations sequentially across the insulating layers, the process achieves the required opening quality while eliminating the harmful heat accumulation effect.
2Manufacturing precision
If more laser shots are performed to ensure complete opening formation, then opening quality improves, but processing time increases reducing wafer-per-hour yield
Solution Approach 1:
The patent segments the laser drilling operation into a predetermined sequence of shots at different locations, optimized to achieve complete opening formation in the minimum number of steps. This segmented approach ensures quality while controlling processing time, thereby maintaining high wafer-per-hour yield.
Solution Approach 2:
The patent employs a predetermined sequence of laser shots that is pre-optimized to achieve complete opening formation. By planning the shot locations and sequence in advance, the process ensures that the openings are fully formed with the minimum necessary shots, preventing both under-drilling and excessive processing time.
3Productivity
If laser shots are concentrated on limited areas to form openings, then opening formation is efficient, but dendrite formation increases due to localized heat
Solution Approach 1:
The patent segments the laser energy application across multiple locations rather than concentrating it on limited areas. By distributing the laser shots throughout the insulating layers at different positions, the process maintains efficient opening formation while preventing localized heat concentration that would cause dendrite formation on exposed pads.
Solution Approach 2:
The patent converts the potential harm of concentrated laser energy into a benefit by deliberately distributing the energy across multiple locations. This distribution strategy transforms what would be a harmful concentration effect into a beneficial spread-out approach, achieving both efficiency and preventing dendrite formation.
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 laser drilling process enhances the efficiency of forming openings in semiconductor packages by reducing heat accumulation, dendrite formation, and delamination, thereby improving yield and reliability.
Implementation Method 1
A first laser shot is performed, location by location, on each of the locations across the package. A first laser spot of the first laser shot overlaps with each of the locations. The first laser shot removes a first portion of the insulating layer below the first laser spot.
Data Source
AI summary
A method includes forming an insulating layer over a package. The package has a plurality of locations where openings are subsequently formed. A first laser shot is performed, location by location, on each of the locations across the package. A first laser spot of the first laser shot overlaps with each of the locations. The first laser shot removes a first portion of the insulating layer below the first laser spot. Another laser shot is performed, location by location, on each of the locations across the package. Another laser spot of the another laser shot overlaps with each of the locations. The another laser shot removes another portion of the insulating layer below the another laser spot. Performing the another laser shot, location by location, on each of the locations across the package is repeated multiple times, until desired portions of the insulating layer are removed.