Power Semiconductor Device with Dielectric Edge Termination
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Solution Overview
Problem
RF power transistors face challenges in operating at higher frequencies with improved linearity, thermal management, and reduced parasitics, while maintaining manufacturing simplicity and cost-effectiveness, especially in high-power and high-frequency applications.
Innovation Solution
The design incorporates a silicon semiconductor die with a p-type substrate, eliminating wire bonds by using a centrally located first electrode interconnection region for both electrical and thermal conductivity, and a dielectric platform for edge termination and capacitance reduction, along with a mesh transistor cell structure for improved frequency response and heat management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wire bonds are used for electrical connection, then electrical connectivity is achieved, but parasitic inductance and manufacturing complexity increase
Solution Approach 1:
The patent extracts and eliminates the wire bond component from the device architecture. By forming direct metallurgical connections between the substrate contact and external leads through the substrate itself, the invention removes the parasitic inductance introduced by wire bonds while simplifying the manufacturing process.
Solution Approach 2:
The patent merges the electrical connection function and thermal management function into a single integrated substrate structure. The substrate serves simultaneously as the electrical pathway for current flow and as the thermal conduction path for heat removal, eliminating the need for separate wire bonds and reducing overall device complexity.
2Speed
If operating frequency is increased, then bandwidth is improved, but parasitic effects and thermal management become more challenging
Solution Approach 1:
The patent extracts and eliminates the parasitic inductance introduced by wire bonds by implementing direct substrate-based electrical connections. This removal of parasitic elements enables the device to operate at higher frequencies with improved bandwidth and reduced signal degradation.
Solution Approach 2:
The substrate is designed to perform multiple functions simultaneously: it serves as the electrical conduction path, the thermal conduction path, and the mechanical support structure. This multi-functionality reduces the number of separate components needed and minimizes parasitic effects that would otherwise be introduced by additional interconnect elements.
3Power
If power output is increased, then transmission capability is improved, but thermal dissipation becomes more difficult
Solution Approach 1:
The substrate is designed to perform dual functions: electrical conduction and thermal conduction. By utilizing the substrate's inherent thermal conductivity, the invention provides an efficient heat sinking path that scales with increased power output, enabling higher power transmission while maintaining effective thermal management.
Solution Approach 2:
The patent merges the electrical current path and thermal heat flow path into the same substrate structure. This integration ensures that the regions generating the most heat (where current flows through the active devices) are directly coupled to the thermal conduction path, optimizing heat removal efficiency at high power levels.
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 enhances linearity, thermal efficiency, and frequency performance, while reducing parasitics and manufacturing complexity, enabling reliable operation in high-power and high-frequency RF applications.
Implementation Method 1
a first electrode interconnection region (58) providing an electrical and thermal conduction path from a source electrode of each of the mesh connected transistor cells
Implementation Method 2
a first electrode interconnection region (58) providing an electrical and thermal conduction path from a source electrode of each of the mesh connected transistor cells
Data Source
AI summary
A power transistor includes a plurality of transistor cells. Each transistor cell has a first electrode coupled to a first electrode interconnection region overlying a first major surface, a control electrode coupled to a control electrode interconnection region overlying the first major surface, and a second electrode coupled to a second electrode interconnection region overlying a second major surface. Each transistor cell has an approximately constant doping concentration in the channel region. A dielectric platform is used as an edge termination of an epitaxial layer to maintain substantially planar equipotential lines therein. The power transistor finds particular utility in radio frequency applications operating at a frequency greater than 500 megahertz and dissipating more than 5 watts of power. The semiconductor die and package are designed so that the power transistor can efficiently operate under such severe conditions.