Mesa Stripe Optical Structure With Etch-Stop Capacitance Control
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Solution Overview
Problem
The challenge in semiconductor optical devices is achieving high reliability and reducing parasitic capacitance, particularly during the formation process where depth control of recesses in buried layers is difficult, leading to variations in resin thickness and electrical characteristic fluctuations.
Innovation Solution
The semiconductor optical device incorporates a mesa stripe structure with a buried layer comprising multiple semiconductor layers and resin layers, where the resin layers are placed in recesses with a lower dielectric constant, surrounded by semi-insulating semiconductor layers, and an inorganic insulating film, reducing parasitic capacitance and enhancing high-speed response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a recess is formed in the buried layer to reduce parasitic capacitance, then parasitic capacitance is reduced, but depth control of the recess becomes difficult causing variation in resin thickness
Solution Approach 1:
An etching stop layer is formed at a predetermined position before creating the recess. This stop layer acts as a pre-established reference that automatically limits the etching depth, ensuring consistent recess depth without requiring complex real-time depth control during the etching process.
Solution Approach 2:
The etching stop layer serves as an intermediary element between the recess formation process and the final resin embedding. It mediates the etching process by providing a physical barrier at the desired depth, thereby controlling recess depth indirectly through material selection rather than direct mechanical or temporal control.
2Manufacturing precision
If the etching stop layer is formed directly under the mesa stripe structure, then recess depth can be controlled, but electrical characteristics are affected
Solution Approach 1:
The etching stop layer is selectively positioned only in specific regions where recess formation is required, rather than uniformly under the entire mesa stripe structure. This localized placement allows depth control in recess areas while preserving the electrical characteristics of the mesa stripe structure by avoiding direct interference with its functional region.
Solution Approach 2:
The buried layer is segmented into different functional zones: regions with etching stop layers for recess formation and regions without etching stop layers that remain intact to support the mesa stripe structure. This segmentation allows simultaneous achievement of precise recess depth control and maintenance of electrical characteristics.
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 configuration ensures high reliability and reduces parasitic capacitance, enabling faster operation and maintaining optical and electrical characteristics, with the resin layers effectively lowering capacitance and improving bandwidth.
Implementation Method 1
embedding a resin with a low dielectric constant in the recess
Data Source
AI summary
A semiconductor optical device includes: a semiconductor layer having a projection; a multiple quantum well layer on the projection; a pair of first semiconductor layers in contact with the mesa stripe structure on respective both sides; a pair of second semiconductor layers on the semiconductor layer; a pair of resin layers above the second semiconductor layers; a pair of third semiconductor layers on the second semiconductor layers, each third semiconductor layer surrounding a corresponding one of the resin layers, the third semiconductor layers being different in constituent material from the second semiconductor layers; a first electrode on the semiconductor layer; and a second electrode including a mesa electrode on the mesa stripe structure, a lead-out electrode extending in the second direction from the mesa electrode, and a pad electrode above one of the resin layers, the pad electrode being connected to the lead-out electrode.