Multi-Plane Gate Trench MOSFET for Breakdown Voltage
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Solution Overview
Problem
Existing semiconductor devices fail to achieve high breakdown voltage effectively due to local concentration of electric fields, which can lead to dielectric breakdown.
Innovation Solution
A semiconductor device design featuring a groove part formed deeper than the drift region, with a gate electrode overlapping the channel region, inhibiting the electric field from concentrating between the source and drain regions, and a method of manufacturing involving specific impurity region formation and gate insulating layer placement to control the electric field distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional trench structure is used with drift region surrounding the trench, then the breakdown voltage can be improved, but the electric field concentrates locally at the trench corners and interfaces, leading to dielectric breakdown
Solution Approach 1:
The invention introduces a multi-plane gate structure that extends in multiple spatial dimensions (first plane, second plane, third plane) to control the electric field distribution. By adding dimensional complexity to the gate structure, the patent achieves uniform electric field distribution throughout the drift region, preventing local concentration at trench corners while maintaining high breakdown voltage.
Solution Approach 2:
The patent applies different conductivity types and impurity concentrations to different regions: the drift region has uniform low concentration for high voltage, while source and drain regions have high concentration for low ON-resistance. The multi-plane gate structure also applies different potentials to different planes, creating localized electric field control in specific regions to prevent breakdown while maintaining overall performance.
2Quantity of substance
If multiple trenches are formed in the channel width direction with impurity regions, then the ON-resistance per unit area can be reduced, but the breakdown voltage cannot be sufficiently improved due to electric field concentration
Solution Approach 1:
The multi-plane gate structure adds spatial dimensions to control the electric field in the drift region. By extending gates in first, second, and third planes, the patent achieves uniform electric field distribution that enables high breakdown voltage while maintaining low ON-resistance through optimized source and drain region configurations.
Solution Approach 2:
The patent optimizes impurity concentration parameters across different regions: low concentration in the drift region for high voltage, high concentration in source and drain regions for low resistance. The multi-plane gate structure also utilizes parameter changes in potential distribution across different planes to achieve both low ON-resistance and high breakdown voltage simultaneously.
3Ease of operation
If the gate electrode is formed only over the channel region, then the channel control is sufficient, but the electric field concentrates between source and drain regions leading to premature breakdown
Solution Approach 1:
The gate structure extends beyond the channel region into the drift region through multiple planes (first, second, and third planes). This dimensional extension allows the gate to control both the channel and the electric field distribution in the drift region, preventing concentration between source and drain while maintaining effective channel control.
Solution Approach 2:
The multi-plane gate structure performs multiple functions: it controls the channel current flow, distributes the electric field uniformly in the drift region, and prevents dielectric breakdown. By making the gate structure universal in its functionality, the patent achieves both good channel control and high breakdown voltage without separate structures.
Data Source
AI summary
Disclosed is a semiconductor device whose breakdown voltage is made high by controlling local concentration of an electric field. A source region faces a second plane, one of side faces of a groove part, and a part thereof extends in a direction in parallel to a nodal line of first and second planes. A drift region faces a third plane being the other side face of the groove part opposite to the second plane with a part thereof extending in a direction parallel to the nodal line of the first plane and the third plane, and is formed at a lower concentration than the source region. The drain region is provided so as to be placed on the other side of the drift region opposite to the groove part and so as to touch the drift region, and is formed at a higher concentration than the drift region.