III-Nitride Fin Contact Structures for Reduced Resistance
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Solution Overview
Problem
In III-Nitride devices, such as transistors used in RF communication and power management, high contact resistance leads to energy loss and reduced power efficiency due to internal and external resistances, which are not adequately minimized by existing methods.
Innovation Solution
The solution involves epitaxially growing source and drain structures on a backbone of fin-like structures, increasing the effective surface area for contact, thereby reducing contact resistance by up to 70% and minimizing external resistance, while also eliminating the need for recesses that can damage the material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional contact structures are used in III-N devices, then device fabrication is simpler, but contact resistance and external resistance remain high leading to energy loss
Solution Approach 1:
The patent transitions from planar contact structures to three-dimensional fin-like contact structures. The contact structures extend vertically with multiple fins, increasing the effective contact surface area in the vertical dimension. This dimensional change allows for reduced contact resistance and energy loss without requiring overly complex lateral arrangements.
Solution Approach 2:
The contact structures are divided into multiple discrete fin elements rather than forming a single continuous contact region. These segmented fins are distributed across the contact area, allowing each fin to contribute to current conduction independently. This segmentation increases the total effective contact area while maintaining manufacturability through standard epitaxial growth processes.
2Loss of energy
If recesses are created in the substrate to reduce contact resistance, then contact resistance decreases, but material damage occurs and manufacturing complexity increases
Solution Approach 1:
Instead of removing material (creating recesses) to improve contact, the patent adds material by growing fin-like structures upward from the substrate surface. This inverted approach achieves reduced contact resistance through increased surface area without the harmful effects of substrate damage associated with recess formation. The fins grow epitaxially from the existing substrate, avoiding mechanical stress and material degradation.
Solution Approach 2:
The patent changes the geometric parameters of the contact structures by growing vertical fins with controlled heights and widths. This parameter change increases the effective contact area and reduces contact resistance without requiring recesses. The fin dimensions can be optimized through epitaxial growth conditions, providing a manufacturable solution that avoids the complexity of recess formation and filling processes.
3Loss of energy
If fin-like contact structures are grown epitaxially, then contact resistance is reduced by up to 70%, but manufacturing precision requirements increase
Solution Approach 1:
The fin-like contact structures are formed through self-aligned epitaxial growth processes where the fins grow automatically from the substrate surface in predetermined locations. The growth process itself defines the fin positions and dimensions, reducing the need for subsequent precision machining or alignment steps. The epitaxial growth naturally produces uniform fin structures with controlled dimensions, achieving the required manufacturing precision through the growth mechanism rather than post-processing.
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 significantly reduces contact resistance and external resistance in III-Nitride transistors, enhancing power efficiency and minimizing energy loss during operation.
Implementation Method 1
epitaxially growing source and drain structures on a backbone of fin-like structures
Data Source
AI summary
A device including a III-N material is described. In an example, the device has a terminal structure with a central body and a first plurality of fins, and a second plurality of fins, opposite the first plurality of fins. A polarization charge inducing layer including a III-N material in the terminal structure. A gate electrode is disposed above and on a portion of the polarization charge inducing layer. A source structure is on the polarization charge inducing layer and on sidewalls of the first plurality of fins. A drain structure is on the polarization charge inducing layer and on sidewalls of the second plurality of fins. The device further includes a source structure and a drain structure on opposite sides of the gate electrode and a source contact on the source structure and a drain contact on the drain structure.