HEMT Seed Layer Discharge Structure for Charge Accumulation
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Solution Overview
Problem
High electron mobility transistors (HEMTs) face issues with excessive charge accumulation in the seed layer, affecting device operation, particularly due to material characteristics, leading to large current and high voltage challenges.
Innovation Solution
A semiconductor device and method involving a substrate with a seed layer, compound semiconductor stack layer, and metal layers, where a conductive layer is conformally deposited to cover the metal layers and side surfaces, electrically connecting the seed layer and source/drain metal layers, and a dicing process is performed to form openings for charge discharge, reducing resistance and enhancing operation speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional HEMT structure is used, then the device can operate in high-temperature and high-voltage environments, but excessive charges accumulate in the seed layer affecting normal operation
Solution Approach 1:
The patent extracts the harmful accumulated charges from the seed layer by creating a conductive layer that extends into the substrate, forming a charge discharge path that removes excess charges from the seed layer region
Solution Approach 2:
The conductive layer acts as an intermediary element between the seed layer and the substrate, providing a controlled path for charge discharge and preventing direct harmful interactions between accumulated charges and the active device regions
2Ease of manufacture
If the seed layer is present for material growth, then compound semiconductor layers can be formed, but charge accumulation occurs in the seed layer
Solution Approach 1:
The patent segments the device structure by creating a conductive layer that is spatially separated from the active HEMT regions but connected to the seed layer, allowing the seed layer to fulfill its manufacturing function while isolating its harmful charge accumulation effect
Solution Approach 2:
The patent converts the harmful charge accumulation in the seed layer into a beneficial feature by providing a controlled discharge path, where the accumulated charges are systematically removed through the conductive layer extending into the substrate, transforming a manufacturing necessity into a functional advantage
3Reliability
If metal layers are deposited for source and drain contacts, then electrical connection is established, but device resistance remains high due to charge accumulation
Solution Approach 1:
The patent adds a vertical dimension to the charge discharge path by extending the conductive layer into the substrate beneath the metal layers, creating a three-dimensional charge management structure that complements the planar metal contact configuration
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 solution effectively addresses charge accumulation by electrically connecting the seed layer with the metal layers, reducing device resistance and improving operational speed, thus enhancing the performance of HEMTs in high-temperature, high-voltage environments.
Implementation Method 1
conformally depositing a conductive layer on a bottom and sidewalls of the dicing opening, and covering the source metal layer and the drain metal layer
Implementation Method 2
The conductive layer electrically connects the seed layer and the source metal layer
Data Source
AI summary
A semiconductor device includes: a substrate; a seed layer disposed on the substrate; a compound semiconductor stack layer disposed on the seed layer; and a source metal layer and a drain metal layer disposed on the compound semiconductor stack layer. The semiconductor device further includes a conductive layer at least partially covering the source metal layer and the drain metal layer, and covering opposing side surfaces of the seed layer and opposing side surfaces of the compound semiconductor stack layer. The conductive layer electrically connects the seed layer and the source metal layer.