GaN HEMT Passivation Structure for Gate Oxidation and 2DEG Control
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Solution Overview
Problem
High electron mobility transistors (HEMTs) using gallium nitride (GaN) face manufacturing challenges such as poor electrical performance and uniformity due to etching processes and high temperature environments, leading to issues like gate leakage and 2DEG sheet resistance.
Innovation Solution
A semiconductor device structure is formed with a buffer layer, channel layer, barrier layer, and passivation layers to mitigate strain and oxidation, using epitaxial growth and low-temperature passivation to maintain electrical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional HEMT manufacturing processes are used, then production can proceed with standard methods, but electrical performance and uniformity deteriorate due to gate leakage and 2DEG sheet resistance issues
Solution Approach 1:
The patent segments the HEMT structure into multiple functional layers including buffer layer, channel layer, barrier layer, and compound semiconductor layers. This segmentation allows each layer to be optimized independently for its specific function, improving overall electrical performance while maintaining manufacturing uniformity through controlled layer-by-layer fabrication.
Solution Approach 2:
The patent introduces a compound semiconductor layer as an intermediary between the barrier layer and the gate metal. This intermediate layer acts as a mediator that reduces gate leakage by providing a transition zone with graded composition, thereby improving electrical performance without compromising manufacturing uniformity.
2Ease of manufacture
If etching processes and high temperature environments are applied during manufacturing, then device fabrication can proceed, but electrical performance deteriorates due to gate leakage and reduced uniformity
Solution Approach 1:
The patent modifies manufacturing parameters by using low-temperature passivation processes instead of high-temperature treatments. This parameter change preserves the electrical performance of the HEMT by avoiding thermal damage to the compound semiconductor layers, while still enabling effective fabrication through controlled chemical vapor deposition.
Solution Approach 2:
The patent employs an inert atmosphere during passivation processes to prevent oxidation of the gate metal and compound semiconductor layers. This inert environment protection maintains electrical performance by preventing degradation from oxidative reactions that would otherwise occur during manufacturing.
3Productivity
If passivation layers are applied at high temperature, then manufacturing can proceed efficiently, but gate metal oxidation increases leading to poor electrical performance
Solution Approach 1:
The patent changes the temperature parameter from high-temperature to low-temperature passivation. This parameter modification prevents gate metal oxidation while still achieving effective passivation, thereby improving reliability without significantly compromising manufacturing efficiency through optimized process timing and atmosphere control.
Solution Approach 2:
The patent uses an inert atmosphere during the passivation process to prevent gate metal oxidation. This inert environment allows the passivation to proceed effectively at lower temperatures, maintaining both productivity and reliability by eliminating the oxidation issue that would otherwise require high-temperature processing.
4Ease of manufacture
If strain-induced defects are present in the HEMT structure, then device fabrication can proceed, but electrical performance and uniformity deteriorate
Solution Approach 1:
The patent applies local quality by creating a graded composition in the compound semiconductor layer, where the aluminum content varies through the layer thickness. This local variation in composition strategically manages strain distribution, reducing strain-induced defects in critical regions while maintaining fabrication feasibility and improving overall uniformity.
Solution Approach 2:
The patent uses composite materials by combining multiple semiconductor layers with different compositions and properties. The buffer layer, channel layer, barrier layer, and compound semiconductor layers form a composite structure that manages strain through controlled lattice mismatch, reducing defects while maintaining manufacturing feasibility and improving uniformity.
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
The proposed structure enhances electrical performance and uniformity by reducing strain-induced defects and gate metal oxidation, maintaining desired gate leakage and 2DEG sheet resistance.
Implementation Method 1
A buffer layer, a channel layer, and a barrier layer are sequentially formed on the substrate
Implementation Method 2
The proposed structure enhances electrical performance and uniformity by reducing strain-induced defects and gate metal oxidation
Data Source
AI summary
A semiconductor device and a method of forming the same are provided. The semiconductor includes a substrate, a buffer layer, a channel layer, a burrier layer, a first compound semiconductor layer, a second compound semiconductor layer, a gate metal, a first passivation layer, and a second passivation layer. The buffer layer is disposed on the substrate. The channel layer is disposed on the buffer layer. The burrier layer is disposed on the channel layer. The first compound semiconductor layer is disposed on the barrier layer. The second compound semiconductor layer is disposed on the first compound layer. The gate metal is disposed on the second compound semiconductor layer. The first passivation layer is disposed on the first compound semiconductor layer, the second compound semiconductor layer, and the gate metal. The second passivation layer is disposed on the first passivation layer.