Erbium-Doped Si3N4 Waveguide Bonding for CMOS Photonics
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Solution Overview
Problem
Monolithic integration of erbium-doped silicon nitride (Si3N4) waveguides into Complementary Metal Oxide Semiconductor (CMOS) silicon photonic wafers is challenging due to high temperature annealing requirements that damage metallization and active silicon photonic devices, and erbium contamination is a concern in CMOS fabrication.
Innovation Solution
Heterogeneous integration of erbium-doped Si3N4 waveguide amplifiers with silicon photonic wafers through wafer bonding and substrate removal, allowing separate annealing at elevated temperatures to achieve low background loss and dopant activation, while encapsulating in SiO2 cladding to prevent contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If monolithic integration of erbium-doped Si3N4 waveguides is attempted, then optical gain is improved, but high temperature annealing damages metallization and active silicon photonic devices
Solution Approach 1:
The patent divides the integration into two separate wafers: a silicon photonic wafer containing metallization and active devices, and a separate erbium-doped Si3N4 wafer that can be annealed independently at high temperatures. This segmentation allows the erbium-doped waveguide to achieve optical gain through high-temperature annealing without damaging the temperature-sensitive components on the silicon photonic wafer.
Solution Approach 2:
The patent introduces an intermediary bonding interface between the two separate wafers. The erbium-doped Si3N4 wafer is bonded to the silicon photonic wafer through this interface, allowing optical coupling while maintaining physical separation of the temperature-sensitive components from the high-temperature annealing process.
2Manufacturing precision
If erbium doping is performed in CMOS fabrication, then dopant activation is improved, but erbium contamination occurs
Solution Approach 1:
The patent extracts the erbium doping process from the CMOS fabrication environment. The erbium-doped Si3N4 wafer is fabricated and doped separately outside the CMOS cleanroom, eliminating the risk of erbium contamination to CMOS equipment and processes. Only the finished, pre-doped wafer is introduced to the silicon photonic wafer through bonding.
Solution Approach 2:
The patent uses a separate erbium-doped Si3N4 wafer as an intermediary that has already undergone dopant activation outside the CMOS environment. This intermediary wafer serves as a pre-prepared component that can be integrated without introducing contamination risks to the CMOS fabrication process.
3Object-affected harmful factors
If heterogeneous integration through wafer bonding is used, then contamination risk is reduced, but device complexity increases
Solution Approach 1:
The patent extracts the complex erbium doping and high-temperature annealing processes from the main CMOS fabrication flow. These complex steps are performed separately on a dedicated wafer, simplifying the main CMOS process while isolating the complexity to a separate, manageable component that is integrated through bonding.
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
Enables low-loss silicon nitride photonic devices with improved optical gain and reduced contamination risk, suitable for high-speed computing and optical switching applications without impacting silicon photonic circuits.
Implementation Method 1
an optical amplifier and a photonic assembly... The Si3N4 waveguide is optically coupled to the waveguide
Implementation Method 2
Heterogeneous integration of erbium-doped Si3N4 waveguide amplifiers with silicon photonic wafers through wafer bonding
Implementation Method 3
erbium-doped Si3N4 waveguide... low background loss
Data Source
Figure 1
Figure 2A~2B
Figure 2C~2D
AI summary
In various embodiments, the disclosure relates to an electro-optical device that includes an optical amplifier and a photonic assembly. The optical amplifier may include a first encapsulation layer defining a first bonding surface, and an erbium-doped Si3N4 waveguide, wherein the erbium-doped Si3N4 waveguide disposed within the first encapsulation layer. The photonic assembly may include a substrate, a second encapsulation layer defining a second bonding surface, the second encapsulation layer disposed on the substrate, a modulator, one or more photodetectors, and a waveguide. In various embodiments, the modulator, the one or more photodetectors and the waveguide are disposed within the second encapsulation layer. The one or more regions of the first bonding surface are bonded to the one or more regions of the second bonding surface in various embodiments. The Si3N4 waveguide is optically coupled to the waveguide in various embodiments.