HEMT Electrode Structure Using Conductive Oxides for Low Contact Resistance

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

High electron mobility transistors (HEMTs) face challenges in reducing processing costs while maintaining low contact resistance, particularly due to the use of gold in source and drain electrodes, which is costly and prone to oxidation.

Innovation Solution

The use of a conductive oxide layer stacked on top of a conductive layer in the source and drain electrodes replaces gold, reducing processing costs and preventing oxidation, while maintaining low contact resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If gold is used in source and drain electrodes, then low contact resistance is achieved, but processing cost increases

Engineering Contradiction:

Improvecontact resistanceVSAvoidprocessing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent employs a composite electrode structure consisting of multiple layers including a conductive oxide layer (such as ITO, IZO, or IGZO) combined with metal layers (such as Ti, Al, or Mo). This composite structure achieves low contact resistance while reducing dependence on expensive gold, thereby lowering processing costs while maintaining electrical performance.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent changes the material parameters of the electrode by replacing pure gold with conductive oxide materials that have appropriate electrical conductivity and oxidation resistance. By adjusting the composition and thickness of these oxide layers, the patent optimizes both contact resistance and cost-effectiveness.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If gold is used in source and drain electrodes, then low contact resistance is maintained, but oxidation resistance deteriorates

Engineering Contradiction:

Improvecontact resistanceVSAvoidoxidation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent uses conductive oxide materials that inherently resist oxidation, eliminating the need for protective overcoats that would be required if using reactive metals. The oxide nature of these materials provides built-in oxidation resistance, maintaining long-term reliability without additional protective layers.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Ease of manufacture

If conductive oxide layer is used instead of gold, then processing cost is reduced, but contact resistance may increase

Engineering Contradiction:

Improveprocessing costVSAvoidcontact resistance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent creates a multi-layer composite structure where conductive oxide layers are combined with metal layers to achieve both low contact resistance and cost reduction. The synergistic combination allows the oxide layer to provide oxidation resistance while the metal layer ensures low contact resistance, overcoming the limitations of using either material alone.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS11843046B2High electron mobility transistor (HEMT)

Publication Date: 2023.12.12 UNITED MICROELECTRONICS CORP

AI summary

A high electron mobility transistor (HEMT) includes a buffer layer, a carrier transit layer, a carrier supply layer, a gate, a source electrode and a drain electrode. The buffer layer is on a substrate. The carrier transit layer is on the buffer layer. The carrier supply layer is on the carrier transit layer. The gate is on the carrier supply layer. The source electrode and the drain electrode are at two opposite sides of the gate, wherein each of the source electrode and the drain electrode includes a conductive layer and a conductive oxide layer stacked from bottom to top.