Terahertz Semiconductor Electrode Terrace Structure for Via Reliability
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Solution Overview
Problem
The existing semiconductor elements for terahertz wave generation or detection face challenges in achieving both improved radiation efficiency and reliability, as a thick dielectric layer requires a gentle via hole inclination to prevent parasitic capacitance, but this can lead to incomplete electrode formation and reduced reliability if the inclination is too steep.
Innovation Solution
A semiconductor element design featuring a mesa structure with a dielectric layer and electrodes, where the electrode in the opening has inclined portions with intermediate planar terrace portions, allowing for controlled inclination angles to balance radiation efficiency and electrode formation reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the dielectric layer is thickened to improve radiation efficiency, then terahertz wave radiation efficiency is improved, but the via hole inclination must be gentle which leads to incomplete electrode formation and reduced reliability
Solution Approach 1:
The via hole is segmented into multiple sections with different inclination angles. The upper portion has a gentle inclination to reduce parasitic capacitance and improve radiation efficiency, while the lower portion has a steeper inclination to ensure complete electrode formation and maintain reliability. This segmentation allows each section to optimize for its specific function.
Solution Approach 2:
Different regions of the via hole are given different local qualities in terms of inclination angle. The upper region near the dielectric layer surface has a smaller inclination angle (more gentle) to minimize parasitic capacitance effects, while the lower region near the electrode connection point has a larger inclination angle (steeper) to facilitate complete electrode coverage. This local differentiation resolves the contradiction between radiation efficiency and reliability.
2Object-generated harmful factors
If the via hole inclination is gentle to prevent parasitic capacitance, then parasitic capacitance is reduced, but electrode formation in the via hole becomes incomplete and reliability decreases
Solution Approach 1:
The via hole structure is divided into segments with different inclination characteristics. The upper segment has a gentle inclination to minimize parasitic capacitance, while the lower segment transitions to a steeper inclination to ensure complete electrode formation. This segmentation allows the structure to simultaneously reduce harmful parasitic capacitance while maintaining reliable electrode connectivity.
Solution Approach 2:
The via hole geometry is modified by introducing a vertical dimension variation in inclination angle. Instead of a uniform inclination throughout the via hole depth, the inclination angle changes along the vertical axis, creating a multi-zone structure that optimizes both electrical performance (reducing parasitic capacitance) and manufacturing performance (ensuring electrode formation).
Data Source
AI summary
A semiconductor element for generating or detecting a terahertz wave is provided. The element includes a substrate, a first electrode, a semiconductor layer disposed between the substrate and the first electrode and including a gain medium for the terahertz wave, a dielectric layer disposed to cover the substrate, and a second electrode disposed on the dielectric layer and connected to the first electrode via an opening provided in the dielectric layer. A portion of the second electrode disposed in the opening includes a first inclined portion, a second inclined portion disposed between the first inclined portion and the first electrode and is less inclined than the first inclined portion, and an intermediate portion connecting the first and second inclined portions. The intermediate portion includes a planar terrace and the terrace is less inclined than the first and second inclined portions.