Semiconductor Optical Device Metal Layer Segmentation
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Solution Overview
Problem
The characteristics of a 90-degree optical hybrid in semiconductor devices often deviate from desired performance due to manufacturing variations and die-bonding processes, leading to imbalances in light intensity between channels.
Innovation Solution
A semiconductor optical device design with a specific arrangement of waveguides and a metal layer on the back surface of the substrate, where the metal layer is positioned to avoid the multi-mode interferometers, reducing stress and maintaining desired channel imbalances both before and after die-bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the metal layer is provided continuously across the back surface of the semiconductor substrate, then the bonding strength during die-bonding is improved, but the stress transmitted to the 90-degree optical hybrid causes channel imbalance
Solution Approach 1:
The metal layer is divided into a first metal layer in the first region and a second metal layer in the second region, with a gap between them. This segmentation reduces stress transmission to the 90-degree optical hybrid while maintaining sufficient bonding strength, resolving the contradiction between bonding strength and channel balance
Solution Approach 2:
The metal layer configuration varies by region: the first metal layer is positioned away from the 90-degree optical hybrid to minimize stress, while the second metal layer is positioned closer to provide adequate bonding. This local differentiation optimizes both bonding strength and channel balance in their respective zones
2Area of stationary object
If the metal layer is positioned close to the 90-degree optical hybrid to improve bonding, then the bonding area is increased, but the stress affects the multi-mode interferometers and changes channel imbalance
Solution Approach 1:
By segmenting the metal layer into two separate regions with a gap, the design allows the second metal layer to provide bonding area close to the 90-degree optical hybrid while the gap prevents stress transmission to the multi-mode interferometers, maintaining channel balance stability
Solution Approach 2:
The gap between the first and second metal layers acts as an intermediary that decouples the stress transmission path, allowing the metal layers to provide bonding area while preventing stress from reaching the sensitive 90-degree optical hybrid components
Data Source
AI summary
A semiconductor optical device includes a semiconductor substrate having first to fourth regions, a 90-degree optical hybrid provided in the third region on a principal surface of the semiconductor substrate, first and second waveguides provided in the first region and being optically coupled to the 90-degree optical hybrid, a photodiode provided in the fourth region, a third waveguide provided in the second region to optically couple the 90-degree optical hybrid to the photodiode, and a metal layer provided on a back surface of the semiconductor substrate. The metal layer includes a first part provided in the first region and a second part provided in the second region that is spaced apart from the first part by a distance. The 90-degree optical hybrid has a first length. The distance between the first and second parts is more than or equal to the first length.