Semiconductor Field Plate Electromigration Reduction
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Solution Overview
Problem
Wide bandgap transistor devices face reduced performance due to capacitance between electrodes, and field plates suffer from high electromigration, leading to device failure.
Innovation Solution
Incorporating a semiconductor layer between refractory metal interposer layers in the field plate to reduce electromigration, with specific layer thicknesses and materials like nickel, titanium, and silicon, and a protective overlayer to enhance reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional field plate structures are used, then manufacturing is simpler, but electromigration causes undesirable connections and device failure
Solution Approach 1:
The field plate structure is segmented into multiple distinct layers including adhesion layers, semiconductor layers, and refractory metal interposer layers. Each layer performs a specific function and can be optimized independently, allowing the structure to resist electromigration while remaining manufacturable using standard semiconductor fabrication processes.
Solution Approach 2:
The field plate uses composite material structures with refractory metal interposer layers combined with adhesion layers and semiconductor layers. This composite approach maintains ease of manufacture through compatible fabrication processes while providing superior electromigration resistance compared to conventional single-material field plates.
2Reliability
If metal layers are used in the field plate, then electrical conductivity is achieved, but electromigration of metal atoms occurs over time
Solution Approach 1:
The refractory metal interposer layer serves as an intermediary that protects the conductive metal layers from electromigration. It allows electrical conductivity to be maintained while preventing the direct electromigration of metal atoms that would otherwise occur in conventional field plate structures, thereby extending device lifetime.
Solution Approach 2:
The structure changes the material parameters by using refractory metals with high melting points and low diffusion rates in the interposer layers. This parameter change in material selection and structure fundamentally reduces the electromigration rate while preserving the electrical conductivity needed for field plate functionality.
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
Significantly reduces electromigration, improving the reliability and lifetime of transistor devices by preventing metal movement and maintaining device functionality.
Implementation Method 1
electromigration is the movement or transport of material due to a transfer of momentum between conducting electrons and one or more atoms in the migrating material
Data Source
AI summary
A transistor device includes a semiconductor body, a spacer layer, and a field plate. The spacer layer is over at least a portion of a surface of the semiconductor body. The field plate is over at least a portion of the spacer layer, and includes a semiconductor layer between a first refractory metal interposer layer and a second refractory metal interposer layer. By including the semiconductor layer between the first refractory metal interposer layer and the second refractory metal interposer layer, the electromigration of metals in the field plate is significantly reduced. Since electromigration of metals in the field plate is a common cause of transistor device failures, reducing the electromigration of metals in the field plate improves the reliability and lifetime of the transistor device.