HEMT Back-Electrode Layout for Faster Switching and Heat Dissipation
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Solution Overview
Problem
High electron mobility transistors (HEMTs) face limitations in switching speed due to parasitic inductance/capacitance at wire bonding locations and overheating issues due to the use of sapphire substrates with lower thermal conductivity compared to silicon substrates.
Innovation Solution
The design includes a high electron mobility transistor with a composite semiconductor layer and an electrically conducting structure that features a back electrode and connecting electrodes to mitigate parasitic inductance/capacitance and enhance heat dissipation, using a substrate with dicing lanes to form bodies and back electrodes, and connecting elements to ground the gate electrode directly, reducing contact area and improving thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If wire bonding is used to ground the gate electrode through a gate bond pad, then the gate can be electrically connected to an external structure, but parasitic inductance/capacitance is formed at the wire bonding location, limiting the switching speed
Solution Approach 1:
The patent extracts the gate grounding function from the traditional wire bonding approach and integrates it directly into the substrate structure through a gate electrode connected to a gate grounding pad formed on the substrate surface, eliminating the external wire bonding process and its associated parasitic inductance/capacitance
Solution Approach 2:
The patent merges the gate electrode and gate grounding pad into a single integrated structure formed directly on the substrate, combining the functions of electrical connection and grounding within the same structural element, thereby eliminating the need for separate wire bonding components
2Ease of manufacture
If a sapphire substrate is used to form the heterostructure, then the manufacturing cost is lower than using a silicon substrate, but the thermal conductivity is lower, causing overheating issues during operation
Solution Approach 1:
The patent employs a composite substrate structure combining sapphire and silicon materials, where the sapphire layer provides cost-effective heterostructure formation and the silicon layer provides superior thermal conductivity for heat dissipation, achieving both economic and thermal performance requirements
Solution Approach 2:
The patent segments the substrate into multiple functional layers with different materials - the sapphire layer for low-cost epitaxial growth and the silicon layer for high thermal conductivity - allowing each layer to perform its specialized function independently
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 reduces parasitic inductance/capacitance, increases switching speed, and improves heat dissipation, addressing the overheating issues by efficiently transferring heat energy from the transistor unit to an external structure.
Implementation Method 1
The electrically conducting structure includes a back electrode disposed on the second surface and at least one connecting electrode connecting the gate electrode and the back electrode
Implementation Method 2
In such a heterostructure, a two dimensional electron gas (2DEG) with a high planar charge density and a high electron mobility is formed at an interface between the two semiconductor materials
Data Source
AI summary
A high electron mobility transistor includes a body, a transistor unit, and an electrically conducting structure. The body has a first surface and a second surface opposite to the first surface. The transistor unit includes a composite semiconductor layer disposed on the first surface and an electrode component disposed on the composite semiconductor layer opposite to the first surface. The electrode component includes a gate electrode, a source electrode, and a drain electrode which are spaced apart from one another. The source electrode and the drain electrode are disposed at two opposite sides of the gate electrode. The electrically conducting structure includes a back electrode disposed on the second surface and at least one connecting electrode connecting the gate electrode and the back electrode. A method for manufacturing the high electron mobility transistor is also provided herein.