Vertical Current-Flow HEMT with Buried Interconnects
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Solution Overview
Problem
Conventional high-electron-mobility transistors (HEMTs) face challenges with parasitic interconnections due to complex routing of source, gate, and drain terminals, leading to degradation in high-frequency performance and increased risk of oscillations during switching states.
Innovation Solution
The development of HEMTs with vertical current flow, where each cell has two terminals on one surface and a third terminal on the opposite surface, reducing parasitic interconnections and simplifying routing, utilizing a gallium nitride epitaxial layer on silicon substrates to enhance breakdown voltage and increase cell density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional planar HEMT structure with lateral current flow is used, then source and drain can be disposed at upper surface, but parasitic interconnections increase and high-frequency performance degrades
Solution Approach 1:
The patent transitions from a conventional planar lateral current flow structure to a vertical current flow structure. The source electrode is positioned at the bottom surface of the substrate, the drain electrode at the top surface, and the gate electrode on the front surface, creating a three-dimensional vertical arrangement that eliminates complex lateral routing and reduces parasitic interconnections.
2Ease of operation
If multiple levels of metal interconnects are used for high current handling, then source and drain terminals can be connected, but resistive and inductive parasitics increase
Solution Approach 1:
The patent extracts the source electrode connection from the front surface metallization layers and positions it at the bottom surface of the substrate. This separation removes the source connection from the complex multi-level interconnect structure, eliminating the need for multiple metal layers and reducing both resistive and inductive parasitics associated with lateral current paths.
3Ease of manufacture
If conventional lateral current flow path is used, then source and drain are on same surface, but current path length increases causing higher resistance
Solution Approach 1:
Instead of placing both source and drain electrodes on the same front surface with lateral current flow, the patent inverts the conventional structure by positioning the source electrode at the bottom surface and the drain electrode at the top surface, creating a vertical current path that significantly shortens the current path length and reduces resistive losses.
Data Source
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AI summary
A high-electron-mobility transistor (HEMT) includes a substrate layer (204) of silicon, a first contact (202) disposed on a first surface of the substrate layer, and a number of layers (206, 208, 212) disposed on a second surface of the substrate layer opposite the first surface. A second contact (224) and a gate contact (214) are disposed on those layers. A trench (218) containing conducting material extends completely through the layers and into the substrate layer. In an embodiment of the HEMT, the first contact is a drain contact and the second contact is a source contact. In another embodiment of the HEMT, the first contact is a source contact and the second contact is a drain contact.