HEMT Source Cap Structure for Saturation Current Reduction

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Solution Overview

Problem

High electron mobility transistor (HEMT) devices experience excessive saturation current during high voltage applications, leading to potential device failure due to local heating.

Innovation Solution

A cap structure made of the same material as the gate electrode is laterally coupled to the source contact, partially depleting the channel region and reducing saturation current by acting as a Schottky contact.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If HEMT device operates at high voltage, then power handling capability is improved, but saturation current increases causing local heating and potential device failure

Engineering Contradiction:

Improvepower handling capabilityVSAvoiddevice reliability

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The gate electrode is segmented into two functional parts: the main gate electrode for controlling current flow and a separate cap structure coupled to the source contact for depletion control. This segmentation allows independent optimization of power handling and saturation current reduction functions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The cap structure acts as an intermediary element between the source contact and the channel region. By being laterally coupled to the source contact and positioned adjacent to the channel, it mediates the depletion effect to reduce saturation current while allowing the main gate to maintain power handling capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If cap structure is added to reduce saturation current, then device reliability is improved, but device complexity increases

Engineering Contradiction:

Improvedevice reliabilityVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The cap structure is formed using the same gate electrode material and is laterally coupled to the source contact, merging the depletion function with the existing gate structure. This integration approach adds functionality while minimizing structural complexity and manufacturing steps.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The cap structure serves multiple functions: it creates a Schottky contact for depletion control, acts as a barrier to reduce saturation current, and maintains electrical connection to the source contact. This multi-functionality reduces the need for additional separate components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 cap structure significantly reduces saturation current by up to 60% and enhances the HEMT device's reliability under high voltage conditions, preventing breakdown and failure.

Implementation Method 1

Methodology Applied

Scientific EffectSchottky contact: Electrical Resistance

Data Source

PatentUS20250338539A1Cap structure coupled to source to reduce saturation current in HEMT device

Publication Date: 2025.10.30 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

In some embodiments, the present disclosure relates to an integrated chip. The integrated chip includes a source and a drain over a substrate. A gate is over the substrate and laterally between the source and the drain. A cap structure includes a horizontally extending segment and a vertically extending segment protruding outward from a lower surface of the horizontally extending segment. The vertically extending segment and the horizontally extending segment are laterally between the source and the gate.