Trench MOSFET Doping Layout for Voltage Resistance and Low On-Resistance
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Solution Overview
Problem
MOSFETs used in power switch elements face issues with insufficient voltage resistance in the off-state due to concentrated electric fields at trench corners and high resistance in the on-state, hindering efficient current flow.
Innovation Solution
A manufacturing method involving the formation of trenches, implantation of conductive dopants to create protective doped regions, and the formation of junction field-effect transistor regions to reduce electric fields and resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If trenches are formed on the semiconductor chip surface to increase channel width and density, then the element performance is improved, but the electric field concentration at trench corners causes insufficient voltage resistance in the off-state
Solution Approach 1:
The patent applies local quality by creating distinct doped regions with different electrical properties at specific locations. The protective doped region is formed at the trench bottom corner where electric field concentration occurs, while the junction field-effect transistor region is formed at the trench side surfaces. This localized doping strategy addresses the electric field concentration problem at critical points without altering the overall trench structure that provides high channel density.
Solution Approach 2:
The patent changes the electrical parameters by introducing dopants with different concentrations and conductive types. The protective doped region has a first conductive type with specific doping concentration, while the junction field-effect transistor region has a second conductive type with different doping concentration. These parameter changes modify the electric field distribution and voltage resistance characteristics at the trench regions.
2Reliability
If the power element is in the on-state, then current flow is enabled, but the trench resistance is high which hinders efficient current flow from source to drain
Solution Approach 1:
The patent applies local quality by forming the junction field-effect transistor region specifically at the trench side surfaces where current flow occurs. This region has different doping characteristics (second conductive type) compared to the protective doped region, creating optimal electrical conditions for current flow in the on-state while maintaining the trench structure for voltage resistance in the off-state.
Solution Approach 2:
The patent changes the electrical parameters by introducing a second conductive type dopant in the junction field-effect transistor region. This parameter change reduces the resistance in the current flow path during the on-state, enabling efficient current flow from source to drain while the protective doped region maintains voltage resistance during the off-state.
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
The method simplifies the manufacturing process, achieves uniform doping concentrations, and enhances dielectric withstanding voltage by allowing easier current flow from source to drain.
Implementation Method 1
implanting a surface of the body layer, so that the first conductive dopant having a high concentration is used for doping to form a plurality of first doped regions, and implanting the surface of the body layer, so that the second conductive dopant having a high concentration is used for doping to form a plurality of second doped regions
Implementation Method 2
depositing a first oxide in each of the plurality of trenches, the first oxide filling the plurality of trenches
Data Source
AI summary
A power element and a manufacturing method for the power element are provided. The power element that is manufactured is a trench-type metal oxide semiconductor field-effect transistor having a junction field-effect transistor region. The power element includes a substrate, a drift diffusion layer, a body layer, a plurality of gate trenches, polycrystalline silicon, a plurality of first doped regions, a plurality of second doped regions, a plurality of protective doped regions, a plurality of dielectric layers, and a metal conductive layer.