Discontinuous Barrier Layer for Moisture-Resistant RF Transistors

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Solution Overview

Problem

Narrow bandgap semiconductor materials like silicon and gallium arsenide are not well-suited for high power and high frequency applications due to their small bandgaps and breakdown voltages, and existing transistors face moisture ingress issues that reduce their operating life in humid conditions.

Innovation Solution

A transistor design incorporating a discontinuous barrier layer on a passivation layer with topological changes to reduce moisture ingress, while maintaining parasitic capacitance and RF performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a continuous barrier layer is used to prevent moisture ingress, then moisture protection is improved, but parasitic capacitance increases and RF performance degrades

Engineering Contradiction:

Improvemoisture protectionVSAvoidparasitic capacitance

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The barrier layer is divided into discrete segments positioned at specific locations where moisture ingress is most critical, rather than forming a continuous layer. This segmentation allows moisture protection at key interfaces while leaving gaps that prevent the formation of a continuous capacitive path, thereby reducing parasitic capacitance while maintaining reliability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The barrier layer is applied locally only at critical moisture ingress points such as interfaces between different materials or regions with topological changes, rather than uniformly across the entire device surface. This localized application provides targeted moisture protection while minimizing the overall capacitance introduced by the barrier material

Inventive Principle:

Principle #3Local quality

2Reliability

If passivation layers are added to protect against moisture, then reliability in humid environments is improved, but device complexity increases

Engineering Contradiction:

Improveoperating life in humid conditionsVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The passivation structure is segmented into discrete barrier regions rather than forming a continuous additional layer. This approach provides moisture protection at critical locations while avoiding the complexity of depositing and patterning an entire continuous passivation layer across the device

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The discontinuous barrier layer structure serves multiple functions simultaneously: it provides moisture barrier protection, maintains electrical performance by limiting capacitance, and simplifies fabrication compared to continuous layer approaches. This multi-functionality reduces overall device complexity while achieving reliability goals

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS12438103B2Transistor including a discontinuous barrier layer

Publication Date: 2025.10.07 WOLFSPEED INC

AI summary

A transistor includes a first passivation layer on a semiconductor layer of the transistor between a source contact and a drain contact. The first passivation layer includes a portion having a topological change. The transistor further includes a discontinuous barrier layer on the portion of the first passivation layer having the topological change. The discontinuous barrier layer is configured to reduce ingress of moisture in the portion of the first passivation layer.