Trench Gate Wide-Bandgap Semiconductor With High-k Dielectric Shielding
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Solution Overview
Problem
Wide band gap semiconductor devices face challenges in improving electric characteristics, such as reducing area-specific on-state resistance and device reliability, due to high electric fields in trench dielectrics, which limits their performance and increases manufacturing costs.
Innovation Solution
The implementation of a wide band gap semiconductor device with trench gate structures featuring a high-k dielectric layer and mesa regions, where the shielding region has a larger vertical distance to the surface than the body region, allowing for increased gate-to-source capacitance and reduced drain-induced barrier lowering, thereby reducing on-state resistance and manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If trench gate structures with conventional dielectrics are used to reduce area-specific on-state resistance, then device conductivity improves, but device reliability deteriorates due to high electric fields in trench dielectrics
Solution Approach 1:
The patent changes the dielectric parameter by using high-k dielectric material with higher permittivity than conventional dielectrics. This allows the gate to exert stronger electric field control over the channel while using a thinner dielectric layer, thereby reducing the electric field stress on the dielectric and improving reliability while maintaining low on-state resistance
Solution Approach 2:
The patent employs a composite gate dielectric structure consisting of multiple layers including high-k dielectric material combined with other dielectric materials. This composite structure optimizes both the electric field control and the stress distribution, resolving the contradiction between achieving low on-state resistance and ensuring device reliability
2Productivity
If device geometries are shrunk to reduce costs and increase device functionalities per unit area, then manufacturing costs decrease, but device reliability is limited by high electric fields in trench dielectrics
Solution Approach 1:
By changing the dielectric parameter to high-k material, the patent enables smaller device geometries without compromising reliability. The high-k dielectric allows for reduced dielectric thickness and optimized trench dimensions, facilitating higher device density while maintaining adequate electric field control and reliability
Solution Approach 2:
The patent optimizes the vertical dimension of the trench gate structure by adjusting the dielectric layer thickness and trench depth. This dimensional optimization allows for higher device functionality per unit area while controlling electric field distribution to maintain reliability in scaled-down geometries
3Manufacturing precision
If conventional dielectric layers are used in trench gate structures, then manufacturing is simpler, but area-specific on-state resistance cannot be reduced effectively
Solution Approach 1:
The patent changes the dielectric material parameter to high-k material, which enables reduced on-state resistance through improved gate control. Although this increases dielectric structure complexity, the patent manages this through systematic layer design and integration with existing trench gate fabrication processes
Solution Approach 2:
The patent segments the gate dielectric structure into multiple functional layers, with the high-k dielectric layer positioned to provide optimal electric field control. This segmentation allows for optimized electrical performance while managing manufacturing complexity through modular structure design
4Ease of manufacture
If ion implantation is used to create body regions and shielding regions, then device functionality is achieved, but manufacturing complexity and cost increase
Solution Approach 1:
The high-k dielectric structure enables optimized ion implantation parameters, including reduced implantation energies and doses, due to the enhanced electric field control. This improves manufacturing ease by reducing process complexity while maintaining device performance and reliability
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 configuration enhances charge carrier mobility, reduces ion implantation energies and doses, and allows for smaller cell pitches, leading to improved device reliability and cost reduction while maintaining high electric field tolerance.
Implementation Method 1
The gate dielectric structure includes a high-k dielectric layer
Implementation Method 2
The second mesa region includes a shielding region of a first conductivity type
Data Source
AI summary
A wide band gap semiconductor device includes a semiconductor body having first and second opposing surfaces along a vertical direction. Trench gate structures extend into the semiconductor body from the first surface and include a gate electrode structure and a gate dielectric structure arranged between the gate electrode structure and the semiconductor body. The gate dielectric structure includes a high-k dielectric layer. A first sidewall of a trench gate structure adjoins a first mesa region. A second sidewall of the trench gate structure adjoins a second mesa region. The first mesa region includes a body region of a first conductivity type adjoining the first sidewall. The second mesa region includes a shielding region of the first conductivity type. A bottom side of the shielding region has a larger first vertical distance to the first surface than a bottom side of the body region in the first mesa region.