GaN HEMT Insulating Structure Without CMP Planarization

Solution Overview

Problem

Existing methods for fabricating high electron mobility transistors (HEMTs) using GaN-based materials require planarization steps like chemical mechanical polishing, which can be costly and equipment-intensive, limiting the scalability and yield of the manufacturing process.

Innovation Solution

The method forms an insulating structure for HEMTs through photolithography etching without a planarization step, such as chemical mechanical polishing, ensuring a flat surface is achieved by precise etching and alignment of insulating layers, enabling high-quality transistor production even without a planarization machine.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If chemical mechanical polishing is used for planarization, then a flat surface is achieved, but manufacturing cost and equipment complexity increase

Engineering Contradiction:

Improveflat surfaceVSAvoidequipment complexity

Core Design Contradiction:

ShapeVSDevice complexity

Solution Approach 1:

The patent extracts and removes the chemical mechanical polishing step from the manufacturing process. By using photolithography etching alone, the planarization function is achieved without requiring a planarization machine, thus eliminating the equipment complexity while still obtaining a flat surface suitable for subsequent processing steps.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical planarization process (chemical mechanical polishing) with a photolithography-based etching process. This substitution uses photoresist patterning and etching chemistry to define and flatten the insulating layer surface, eliminating the need for mechanical polishing equipment.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Shape

If chemical mechanical polishing is used for planarization, then a flat surface is achieved, but manufacturing cost increases

Engineering Contradiction:

Improveflat surfaceVSAvoidmanufacturing cost

Core Design Contradiction:

ShapeVSEase of manufacture

Solution Approach 1:

The patent extracts and removes the chemical mechanical polishing step from the manufacturing process. By using photolithography etching alone, the planarization function is achieved without requiring a planarization machine, thus eliminating the equipment complexity while still obtaining a flat surface suitable for subsequent processing steps.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent uses consumable photoresist materials and standard photolithography chemicals to achieve planarization, replacing expensive and maintenance-intensive planarization machines. The photoresist layers are disposable patterned masks that define the insulating layer geometry through etching, providing a cost-effective alternative to mechanical polishing.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Device complexity

If photolithography etching is used without planarization, then equipment dependency is reduced, but manufacturing precision may be compromised

Engineering Contradiction:

Improveequipment dependencyVSAvoidsurface flatness

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent performs preliminary patterning of the insulating layer using photolithography before final processing. By defining the insulating layer boundaries and thickness through photoresist masks and etching steps, the surface geometry is pre-established with sufficient flatness for subsequent transistor fabrication, eliminating the need for post-etch planarization.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces the mechanical planarization process (chemical mechanical polishing) with a photolithography-based etching process. This substitution uses photoresist patterning and etching chemistry to define and flatten the insulating layer surface, eliminating the need for mechanical polishing equipment.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 approach allows for the fabrication of high-yield HEMTs with a flat surface, enhancing the manufacturing process's efficiency and reducing equipment dependency, thus improving the scalability and cost-effectiveness of HEMT production.

Implementation Method 1

an insulating layer of the high electron mobility transistor having a flat surface is formed only by photolithography etching

Methodology Applied

Scientific EffectPhotolithography: Photopolymerisation

Implementation Method 2

an insulating layer of the high electron mobility transistor having a flat surface is formed only by photolithography etching

Methodology Applied

Scientific EffectEtching: Ablation

Data Source

PatentEP3764401B1Insulating structure of high electron mobility transistor and manufacturing method thereof

Publication Date: 2026.01.07 UNITED MICROELECTRONICS CORP

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AI summary

An insulating structure of a high electron mobility transistor (HEMT) is provided, which comprises a gallium nitride layer, an aluminum gallium nitride layer disposed on the gallium nitride layer, a groove disposed in the gallium nitride layer and the aluminum gallium nitride layer, an insulating layer disposed in the groove, wherein a top surface of the insulating layer is aligned with a top surface of the aluminum gallium nitride layer, and a passivation layer, disposed on the aluminum gallium nitride layer and the insulating layer.