Laser Chip Passive Alignment Structure for Silicon Photonics Bonding
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Solution Overview
Problem
Existing data communication systems face challenges in achieving reliable passive alignment for flip-chip bonding of laser chips on silicon photonics chips, particularly in vertical, longitudinal, and lateral directions, which affects optical communication efficiency.
Innovation Solution
A laser chip with 3D passive alignment features, including a chip body with p-region and n-region, vertical stoppers, an active region, alignment marks, and a thin metal film, is designed for sub-micron precision alignment, allowing for doubled vertical alignment tolerance and <3 dB optical loss in high-speed data communication applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional flip-chip bonding is used for laser chip integration, then the bonding process can be completed, but the alignment precision in vertical, longitudinal, and lateral directions is insufficient
Solution Approach 1:
The patent applies preliminary action by pre-forming vertical stoppers, alignment marks, and facet structures on the laser chip before bonding. The vertical stoppers are formed by etching grooves and filling with reflective material, while alignment marks are created through selective oxidation or deposition. These pre-formed features enable passive alignment during bonding without requiring complex real-time adjustment mechanisms, thus improving alignment precision while controlling device complexity
Solution Approach 2:
The patent implements self-service through self-aligned bonding mechanisms where the vertical stoppers and alignment marks automatically guide the positioning of the laser chip relative to the waveguide. The reflective facet provides automatic longitudinal alignment through light reflection feedback. These self-aligning features eliminate the need for external alignment equipment and complex bonding processes, achieving sub-micron precision alignment while maintaining relatively simple device structure
2Reliability
If alignment tolerance is increased to improve bonding reliability, then more chips can be successfully bonded, but optical coupling efficiency decreases
Solution Approach 1:
The patent applies dimensionality change by introducing vertical stoppers that extend in the vertical dimension, providing alignment reference in three dimensions (vertical, longitudinal, and lateral). The vertical stoppers create a reference plane that enables tolerance compensation in the vertical direction while maintaining precise lateral and longitudinal alignment through alignment marks. This multi-dimensional alignment approach increases bonding reliability without compromising optical coupling efficiency by ensuring the laser active region remains properly positioned relative to the waveguide mode field
3Ease of manufacture
If passive alignment is used to simplify the bonding process, then the bonding complexity is reduced, but alignment precision in all three directions is insufficient
Solution Approach 1:
The patent applies preliminary action by pre-forming vertical stoppers, alignment marks, and facet structures on the laser chip before bonding. The vertical stoppers are formed by etching grooves and filling with reflective material, while alignment marks are created through selective oxidation or deposition. These pre-formed features enable passive alignment during bonding without requiring complex real-time adjustment mechanisms, thus improving alignment precision while controlling device complexity
Solution Approach 2:
The patent implements self-service through self-aligned bonding mechanisms where the vertical stoppers and alignment marks automatically guide the positioning of the laser chip relative to the waveguide. The reflective facet provides automatic longitudinal alignment through light reflection feedback. These self-aligning features eliminate the need for external alignment equipment and complex bonding processes, achieving sub-micron precision alignment while maintaining relatively simple device structure
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 solution enables precise 3D passive alignment with improved optical coupling efficiency and increased vertical alignment tolerance, supporting high-speed data communication demands by ensuring accurate positioning of the laser chip relative to the waveguide, thereby enhancing the reliability and efficiency of optical communication systems.
Implementation Method 1
a thin metal film on the surface of the p-region having a cleaved edge shared with the front facet
Implementation Method 2
a pair of first vertical stoppers formed respectively beyond two sides of the chip body based on a wider width of the n-region
Implementation Method 3
a first alignment mark in the longitudinal direction formed on a top surface of the p-region near the front facet with a lateral distance defined in sub-micron precision
Data Source
AI summary
A laser chip for flip-chip bonding on a silicon photonics chip with passive alignment features. The laser chip includes a chip body made of a p-region and a n-region in vertical direction and extended from a front facet to a rear facet in longitudinal direction, a pair of first vertical stoppers formed respectively beyond two sides of the chip body based on a wider width of the n-region, an active region buried in the chip body between the p-region and the n-region in the vertical direction and extended from the front facet to the rear facet in the longitudinal direction, an alignment mark formed on a top surface of the p-region near the front facet with a lateral distance defined in sub-micron precision relative to the active region; and a thin metal film on the surface of the p-region having a cleaved edge shared with the front facet.