Trench MOSFET Drift Region Layout for Low On-Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In semiconductor devices, particularly MOS transistors, the on-resistance is limited by the voltage-withstand capability, making it difficult to further reduce on-resistance while maintaining device performance.
Innovation Solution
A semiconductor device structure incorporating a drift region with a first conductivity type, a body region, doped regions, and trench gates with conductive structures and dielectric layers, where the extension region surrounds the trench gate to enhance depletion and breakdown voltage, allowing increased doping concentration for reduced on-resistance without compromising voltage withstand.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the doping concentration of the drift region is increased to reduce on-resistance, then the on-resistance decreases, but the voltage-withstand capability deteriorates
Solution Approach 1:
The drift region is segmented into multiple regions with different doping concentrations: a first drift region with higher doping concentration (to reduce on-resistance) and a second drift region with lower doping concentration (to maintain voltage-withstand capability). This segmentation allows each region to optimize for its specific function, resolving the contradiction between low on-resistance and high voltage withstand.
Solution Approach 2:
Different regions of the drift region are assigned different doping concentrations based on their local functional requirements. The region near the body region has higher doping to reduce conduction loss, while the region extending toward the opposite electrode has lower doping to enhance breakdown voltage. This local quality differentiation enables simultaneous optimization of both on-resistance and voltage-withstand capability.
2Loss of energy
If a trench gate structure is used to increase conduction channel density, then the on-resistance decreases, but the voltage-withstand capability is weakened
Solution Approach 1:
The invention transitions from a conventional planar gate structure to a three-dimensional trench gate structure that extends vertically into the drift region. This dimensional change allows the gate to control conduction channels in multiple dimensions, significantly increasing channel density and reducing on-resistance while the segmented drift region architecture maintains voltage-withstand capability through strategic doping distribution.
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 proposed structure reduces on-resistance while maintaining or improving voltage withstand, enhancing the stability and efficiency of semiconductor devices by transferring the breakdown position and uniformly distributing depletion regions.
Implementation Method 1
a dielectric layer being formed between the second conductive structure and the inner wall of the first trench, as well as between the first conductive structure and the inner wall of the first trench not surrounded by the extension region
Implementation Method 2
the first doped region has the first conductivity type, the second doped region has the second conductivity type
Data Source
AI summary
A semiconductor device comprises a drift region (100), a body region (110), a first doped region (111) and a second doped region (112)); a first trench penetrates the first doped region (111), the body region (110) extends into the drift region (100); an extension region (150) having an opposite conductivity type to the drift region (100) and surrounding the bottom wall of the first trench; where the first trench is filled with a first conductive structure (141) and a second conductive structure (142); a dielectric layer (130) formed between the second conductive structure (142) and the inner wall of the first trench, as well as between the first conductive structure (141) and the inner wall of the first trench; a second trench penetrating the first doped region (111) and the body region (110), and a dielectric layer (130) located between the third conductive structure (143) and the second trench (122).