Laser Die Cavity Integration for Shorter Thermal Paths
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Solution Overview
Problem
The integration of lasers in photonics integrated circuits (PICs) often faces challenges related to thermal performance and manufacturing efficiency, with existing methods not adequately addressing thermal management and fabrication costs.
Innovation Solution
The described method involves integrating a laser within a cavity of a wafer with the n-layer proximate to a heat sink, using conductive and insulating layers to route signals and enhance thermal contact, and employing optical fill materials and conductive posts for improved thermal spreading and electrical connectivity, while also optimizing the fabrication process for reduced thermal paths and enhanced bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the laser is integrated in a conventional manner in the PIC, then the fabrication process is simpler, but the thermal performance deteriorates due to longer thermal paths and poor thermal contact
Solution Approach 1:
The patent inverts the conventional laser integration approach by bonding the laser die with the n-layer closer to the heat sink rather than the p-layer. This inversion creates a shorter thermal path from the laser active region to the heat sink, significantly improving thermal performance and reducing thermally-induced performance degradation.
Solution Approach 2:
The patent introduces a vertical cavity structure in the wafer, creating a three-dimensional thermal management architecture. The heat sink is positioned at the bottom of the cavity, directly beneath the laser die, establishing a vertical thermal conduction path that reduces thermal resistance and improves heat dissipation efficiency.
2Temperature
If additional conductive and insulating layers are deposited to improve thermal contact, then thermal management improves, but manufacturing time and cost increase
Solution Approach 1:
The patent combines multiple functions into the laser die bonding process itself. The bonding step simultaneously achieves electrical connection, mechanical attachment, and thermal contact by directly bonding the laser die to the wafer with the heat sink, eliminating the need for separate thermal interface materials or additional bonding steps.
Solution Approach 2:
The n-layer of the laser die serves multiple functions: it provides electrical connection to the n-contact, acts as a thermal conduction path to the heat sink, and serves as a bonding interface to the wafer. This multi-functionality reduces the need for additional layers and simplifies the fabrication process.
3Temperature
If the n-layer is positioned closer to the heat sink, then thermal spreading improves, but electrical connection complexity increases
Solution Approach 1:
The patent inverts the conventional electrical connection approach by routing the n-contact connection through the bonding interface to the heat sink side, rather than connecting the p-contact to the heat sink. This inversion simplifies the electrical connection architecture while maintaining optimal thermal paths.
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 approach enhances thermal contact and reduces thermally-induced performance degradation of the laser, improving the overall efficiency and reliability of the integrated photonics device while streamlining the manufacturing process.
Implementation Method 1
A heat sink can be located on the other side of the bottom of the cavity such that the n-layer of the light source is located proximate to the heat sink. The proximity of the n-layer of the light source to the heat sink can create a shorter thermal path, which can enhance thermal contact and heating spreading.
Data Source
AI summary
Described herein are one or more methods for integrating an optical component into an integrated photonics device. The die including a light source, an outcoupler, or both, may be bonded to a wafer having a cavity. The die can be encapsulated using an insulating material, such as an overmold, that surrounds its edges. Another (or the same) insulating material can surround conductive posts. Portions of the die, the overmold, and optionally, the conductive posts can be removed using a grinding and polishing process to create a planar top surface. The planar top surface enables flip-chip bonding and an improved connection to a heat sink. The process can continue with forming one or more additional conductive layers and/or insulating layers and electrically connecting the p-side and n-side contacts of the laser to a source.