Photonic Engine Facet Formation for Smoother Optical Sidewalls
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Solution Overview
Problem
Existing photonic packages face challenges in achieving smooth sidewalls for optical signals, leading to increased signal scattering and loss due to rough etching processes.
Innovation Solution
Implementing a method for forming photonic packages using a two-photos-two-etching (2P2E) process to form sidewalls of the EIC dies are smoother, and the sidewalls of the resulting package are smoother. The method comprises forming a reconstructed wafer with a supporting substrate, an electronic die, and a photonic die, followed by a first etching process to create a first trench and a second etching process to extend the trench to the supporting substrate, and then sawing the substrate to form a photonic package.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single etching process is used to form sidewalls, then the manufacturing process is simpler and faster, but the sidewalls become rough leading to increased optical signal scattering and loss
Solution Approach 1:
The patent divides the single etching process into two separate etching processes: a first etching process that forms initial sidewalls, and a second etching process that refines the sidewalls to achieve smooth surfaces. This segmentation allows each process to be optimized for its specific function, with the second process using adjusted parameters to minimize roughness while the first process removes the majority of material efficiently.
2Loss of energy
If a single etching process is used, then the manufacturing time is shorter, but the optical signal loss increases due to rough sidewalls
Solution Approach 1:
The etching process is segmented into two stages: the first etching process removes the bulk of material to form the basic sidewall structure, while the second etching process applies optimized parameters (such as reduced power, adjusted gas flow, or modified chemistry) to selectively smooth the sidewalls with minimal material removal. This ensures low optical loss while maintaining reasonable throughput by not duplicating the full etching sequence.
Solution Approach 2:
The patent changes etching parameters between the two processes, such as adjusting plasma power, pressure, gas composition, or etch chemistry, to optimize the second process for sidewall smoothing rather than material removal. This parameter optimization reduces sidewall roughness and associated optical losses without proportionally increasing process time.
3Productivity
If stronger etching is used to remove material faster, then the etching speed increases, but the sidewall roughness increases causing more signal scattering
Solution Approach 1:
The patent segments the etching operation so that the first process uses higher power or more aggressive chemistry to remove material rapidly, while the second process uses milder, optimized conditions to smooth the sidewalls. This segmentation decouples the conflicting requirements of speed and quality into separate sequential operations.
Solution Approach 2:
The patent changes etching parameters between processes, using aggressive parameters (higher power, different chemistry) for the first process to maximize removal rate, then switching to conservative parameters (lower power, optimized chemistry) for the second process to minimize roughness. This dynamic parameter adjustment resolves the contradiction between etching speed and surface quality.
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 smoother sidewalls reduce optical signal loss and improve signal transmission efficiency by controlling the etching process to minimize roughness.
Implementation Method 1
performing a first etching process to form a first trench in the reconstructed wafer, wherein the photonic die comprises a first sidewall facing the first trench; performing a second etching process to form a second trench
Data Source
AI summary
A method includes forming a reconstructed wafer, which includes a supporting substrate, an electronic die over the supporting substrate, and a photonic die over the electronic die. The method further includes a first etching process to form a first trench in the reconstructed wafer, and a second etching process to form a second trench. The photonic die has a first sidewall facing the first trench. The second trench extends from a bottom of the first trench to the supporting substrate, and the second etching process results in a second sidewall facing the second trench. The method further includes forming a protection layer on the first sidewall and the second sidewall, and sawing the supporting substrate to form a photonic package comprising the photonic die, the electronic die, and a portion of the supporting substrate