Transistor With Dielectric Platform Reduces Gate-Drain Capacitance
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Solution Overview
Problem
Transistors face challenges in increasing power density while maintaining device breakdown voltage and effective heat removal, leading to limitations in performance and efficiency.
Innovation Solution
The design incorporates a trench structure with a dielectric platform and angled n-type doping to enhance current density and voltage breakdown, along with a fourth electrode to reduce parasitics and increase packing density, allowing for higher performance and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the physical size of the die is reduced to increase power density, then device performance and packing density improve, but device breakdown voltage and heat removal capability deteriorate
Solution Approach 1:
The patent introduces a dielectric platform structure that extends vertically from the substrate surface, creating a three-dimensional architecture. This vertical dimension allows the transistor active region to be positioned over the platform, effectively increasing the breakdown voltage by adding vertical distance for voltage standoff while maintaining a compact horizontal footprint. The platform height provides an additional dimensional parameter to optimize both power density and breakdown voltage simultaneously.
Solution Approach 2:
The dielectric platform acts as an intermediary structure between the substrate and the transistor active region. This intermediate dielectric layer provides electrical isolation and voltage standoff, enabling the transistor to achieve higher breakdown voltage without increasing the horizontal die size. The platform mediates between the conflicting requirements of compact size and high voltage capability by providing a vertical isolation barrier.
2Productivity
If the physical size of the die is reduced to increase power density, then packing density improves, but heat removal capability deteriorates
Solution Approach 1:
The dielectric platform creates vertical separation between the heat-generating transistor active region and the substrate, allowing for improved thermal management. The platform structure enables thermal vias or heat sinks to be positioned strategically, creating a three-dimensional thermal pathway that enhances heat removal efficiency without increasing the horizontal die area.
3Reliability
If transistor size is increased to improve voltage breakdown, then power density decreases
Solution Approach 1:
The dielectric platform transfers the voltage breakdown function from the horizontal plane to the vertical dimension. By positioning the transistor active region over a raised dielectric platform, the breakdown voltage is enhanced through vertical distance rather than horizontal expansion. This allows the transistor to maintain high power density with a compact footprint while achieving the required voltage breakdown through the platform height.
Data Source
AI summary
A semiconductor device is formed having lower gate-to-drain capacitance. The semiconductor device having an active region (1300) and a dielectric platform region (1310). A trench (80) is formed adjacent to a drain (20) of the semiconductor device to a first depth. The etch process for forming trench (80) etches the dielectric platform region (1310) to a first depth. A second trench (210) is etched in trench (80) to further isolate areas in the active region (1300). The etch process for forming the second trench (210) etches the dielectric platform region (1310) to form a support structure for the dielectric platform in the substrate. The dielectric platform, the trench (80), and the second trench (210) is capped and sealed. The dielectric platform is made approximately planar to the major surface of the substrate by forming the support structure from the first depth to the second depth.