Semiconductor Field Plate Refractory Metal Interposer Electromigration
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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 refractory metal interposer layer between current carrying layers in the field plate to reduce electromigration, while maintaining conductive capabilities, thereby enhancing the reliability and performance of transistor devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a field plate is used to reduce capacitance between electrodes, then device performance (gain, breakdown voltage) is improved, but electromigration of conductive materials increases leading to device failure
Solution Approach 1:
The field plate is constructed using a composite material structure consisting of a refractory metal layer (such as tungsten, molybdenum, or nickel) combined with a conductive material layer (such as aluminum, copper, or gold). This composite structure leverages the electromigration resistance of refractory metals while maintaining the high conductivity needed for field plate functionality, thereby resolving the contradiction between reliability and electromigration susceptibility.
Solution Approach 2:
The refractory metal layer acts as an intermediary between the conductive material and the underlying spacer layer. This intermediate layer prevents direct contact and potential electromigration pathways between the conductive material and the spacer, while still allowing the field plate to perform its intended function of reducing capacitance and managing electric fields.
2Reliability
If current carrying materials are used in the field plate to maintain conductive capabilities, then electrical functionality is preserved, but electromigration causes material movement and connection failure
Solution Approach 1:
The field plate uses a composite structure where a refractory metal layer provides structural stability and electromigration resistance, while a conductive material layer maintains electrical functionality. The refractory metal's stable composition prevents material migration, while the conductive layer ensures proper electrical connections are maintained throughout device operation.
Solution Approach 2:
The refractory metal layer serves as a stable intermediary that anchors the conductive material, preventing it from migrating into or through the spacer layer. This intermediate structure maintains both the compositional stability of the field plate and the reliability of electrical connections.
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 in field plates, improving the reliability and lifetime of transistor devices by preventing metal movement and maintaining conductive 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. By including the refractory metal interposer layer between the first current carrying layer and the second current carrying layer, the electromigration of metals in the field plate is significantly reduced.
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 first current carrying layer, a refractory metal interposer layer over the first current carrying layer, and a second current carrying layer over the refractory metal interposer layer. By including the refractory metal interposer layer between the first current carrying layer and the second current carrying 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.