HEMT Passivation Structure for Lower Leakage and Higher Breakdown
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Solution Overview
Problem
There is a need to improve the manufacturing methods and performance of high electron mobility transistors (HEMTs), particularly in terms of their passivation layers to enhance reliability and efficiency, as existing HEMTs face challenges with leakage currents and breakdown voltage.
Innovation Solution
The proposed HEMT transistor design incorporates a first passivation layer of alumina and a second passivation layer of aluminum nitride, both extending over specific portions of the semiconductor surface, which helps protect the surface from oxidation and dangling bonds, and introduces positive charges to increase electronic density in the two-dimensional electron gas channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single passivation layer is used in HEMT, then the manufacturing process is simple, but leakage currents increase and breakdown voltage decreases
Solution Approach 1:
The patent divides the passivation layer into two separate layers: a first passivation layer (alumina) and a second passivation layer (aluminum nitride). This segmentation allows each layer to perform specific functions - the alumina layer provides excellent electrical insulation to reduce leakage currents, while the aluminum nitride layer provides mechanical protection and stress control to enhance breakdown voltage. The segmented structure resolves the contradiction by achieving high reliability without significantly complicating the manufacturing process.
Solution Approach 2:
The patent employs a composite passivation structure combining two different materials - alumina and aluminum nitride - each with distinct properties. The alumina layer contributes high electrical resistance and low dielectric constant for leakage current suppression, while the aluminum nitride layer provides high mechanical strength and stress control for breakdown voltage enhancement. This composite approach achieves superior overall performance that neither material could provide alone.
2Reliability
If passivation layer coverage is increased to protect the surface, then surface protection improves, but manufacturing complexity increases
Solution Approach 1:
The patent applies different passivation materials to different regions of the semiconductor surface based on local requirements. The first passivation layer (alumina) is applied to areas requiring electrical insulation, while the second passivation layer (aluminum nitride) is applied to areas requiring mechanical protection and stress control. This localized application strategy provides optimal surface protection without uniformly increasing device complexity across the entire structure.
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 design effectively reduces leakage currents, increases the avalanche voltage, and improves the tradeoff between on-state resistance and off-state leakage, enhancing the overall performance and reliability of the HEMT transistors.
Implementation Method 1
protect the surface from oxidation and dangling bonds
Implementation Method 2
introduces positive charges to increase electronic density in the two-dimensional electron gas channel
Data Source
AI summary
The present disclosure relates to a HEMT transistor comprising a first semiconductor layer, a gate arranged on a first surface of the first semiconductor layer, a first passivation layer made of a first material on the sides of the gate, the first passivation layer further extending over a first portion of said surface of the first semiconductor layer, and a second passivation layer made of a second material different from the first material on a second portion of said surface of the first semiconductor layer next to the first passivation layer.