Interdigitated GaN HEMT-SBD Layout for Low Reverse Conduction
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Solution Overview
Problem
Existing Group III nitride-based semiconductor devices face challenges in achieving superior reverse conduction capability without increasing forward conduction resistance, particularly in high-frequency applications, due to the inherent limitations of p-GaN gate HEMTs and the complexity of integrating Schottky barrier diodes.
Innovation Solution
An interdigitated GaN-based Schottky barrier diode/transistor structure is integrated into a common Group III nitride body, with a gate electrode structure and Schottky metal contacts arranged to form alternate transistor and diode sections, utilizing an ohmic metal layer for electrical connection and a field plate design to optimize conduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a Schottky barrier diode is integrated into a Group III nitride transistor device, then reverse conduction capability is improved, but device complexity increases
Solution Approach 1:
The patent combines the Schottky barrier diode and transistor device into a single integrated structure sharing a common Group III nitride body, source contacts, and drain/cathode finger. This merging approach improves reverse conduction capability while minimizing the increase in device complexity by reusing common structural elements between the diode and transistor sections.
Solution Approach 2:
The integrated device is segmented into distinct transistor sections and Schottky barrier diode sections along the length of the device. The gate electrode structure is selectively positioned to define these segments, with gate material present in transistor sections and absent in diode sections. This segmentation allows independent optimization of each function within the integrated structure.
2Reliability
If Schottky metal contacts are arranged between source contacts, then reverse conduction voltage is reduced, but manufacturing complexity increases
Solution Approach 1:
The gate electrode structure is formed first, with gate material deposited and patterned to define the alternating transistor and diode sections. The Schottky metal contacts are then formed in subsequent processing steps, utilizing the pre-defined gate structure as a template. This preliminary formation of the gate structure simplifies the overall manufacturing process by establishing the section boundaries before adding the Schottky contacts.
Solution Approach 2:
The gate electrode structure serves a dual function: it provides gate control for the transistor sections and simultaneously defines the locations where Schottky metal contacts should be formed. The absence of gate material in certain regions automatically indicates where diode sections with Schottky contacts should be created, reducing the need for separate positioning steps.
3Area of stationary object
If an interdigitated structure is used, then area effectiveness is improved, but fabrication difficulty increases
Solution Approach 1:
The patent arranges the transistor and diode sections in an interdigitated pattern along the length of the device, utilizing the longitudinal dimension to create alternating functional sections. This one-dimensional arrangement along the device length achieves area effectiveness without requiring complex two-dimensional or three-dimensional structures, simplifying the fabrication process.
Solution Approach 2:
The common source contacts and drain/cathode finger serve multiple functions: they provide electrical connections for both the transistor sections and the Schottky barrier diode sections. This multi-functionality reduces the total number of separate components needed, improving area effectiveness while simplifying the fabrication process by reducing the number of distinct fabrication steps.
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 configuration achieves low reverse conduction voltage with minimal impact on forward conduction, providing a more area-effective solution compared to traditional two-device structures and allowing for a self-aligned gate process, reducing complexity and improving performance.
Implementation Method 1
a Schottky barrier diode (SBD) may be included
Implementation Method 2
The source contacts are electrically coupled to one another and to the Schottky metal contacts by an ohmic metal layer
Data Source
AI summary
In an embodiment, a semiconductor device is provided that includes a Group III nitride transistor device and a Schottky barrier diode integrated in a Group III nitride body. A common drain/cathode finger is arranged on the Group III nitride body. Two or more source contacts are arranged on the Group III nitride body and spaced apart in a row, the row being spaced laterally apart from, and extending substantially parallel to, the common drain/cathode finger. A gate electrode structure and one or more Schottky metal contacts are arranged on the Group III nitride body. At least one Schottky metal contact is arranged between and spaced apart from neighbouring ones of the source contacts. The gate electrode structure includes a closed ring section for each source contact that laterally surrounds that source contact. Neighbouring closed ring sections are connected by a gate connection section.