Laser Diode Resin Ceiling Reduces Parasitic Capacitance
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Solution Overview
Problem
Existing laser diodes face issues with parasitic capacitance due to the proximity of the metal layer to the semiconductor layer and the potential for insulating portions to sag into hollows, affecting their performance and manufacturing stability.
Innovation Solution
A laser diode design featuring a ridge portion with channel and terrace structures, where resin supporting portions and a ceiling layer with hollow portions are used to separate the metal layer from the semiconductor, reducing parasitic capacitance and preventing sagging, while ensuring the formation of hollow portions along the mesa stripe.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the metal layer is placed close to the semiconductor layer, then the device structure is simplified, but parasitic capacitance increases and affects laser diode characteristics
Solution Approach 1:
A resin layer is introduced as an intermediary material between the metal layer and the semiconductor layer. This resin layer acts as a spacer that increases the distance between the metal and semiconductor, thereby reducing parasitic capacitance while still allowing the metal layer to be positioned over the groove portions for electrical contact functionality.
Solution Approach 2:
The invention transitions from a two-dimensional planar arrangement to a three-dimensional structure by forming groove portions that extend vertically into the semiconductor layer. This vertical dimension allows the metal layer to be positioned closer to the semiconductor in the vertical direction while maintaining horizontal separation through the resin filling, thus reducing parasitic capacitance without sacrificing electrical contact efficiency.
2Reliability
If insulating portions are placed in hollows, then electrical isolation is improved, but the insulating portion may sag into the hollows affecting structural integrity
Solution Approach 1:
The invention uses a composite structure combining resin material and semiconductor material. The resin is filled into the groove portions to form a composite structure where the resin provides both electrical isolation and mechanical support, preventing sagging while maintaining the hollow portions for electrical contact.
Solution Approach 2:
The resin layer is placed beforehand in the groove portions to provide structural support and prevent the metal layer or other components from sagging into the hollows during subsequent manufacturing processes or device operation. This prior cushioning ensures both electrical isolation and structural integrity are maintained.
Data Source
AI summary
A laser diode includes a ridge portion, channel portions located adjacent to the ridge portion such that the ridge portion is sandwiched, the channel portions being shorter in height than the ridge portion, terrace portions adjacent to opposite sides of the respective channel portions from the ridge portion and longer in height than the channel portions, supporting portions provided over the respective channel portions, separated from side surfaces of the ridge portion or side surfaces of terrace portions or both, and made of resin, a ceiling portion including first portions provided over the supporting portions and second portions continuous with the first portions and located over the respective channel portions with hollow portions interposed therebetween, the ceiling portion being made of resin, and a metal layer provided over the ceiling portion and connected to an upper surface of the ridge portion.