Trench Semiconductor Structure With Field Plate Capacitance Isolation
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Solution Overview
Problem
Semiconductor devices with trench gate structures face challenges in achieving high breakdown voltage and low ON-resistance while minimizing source-gate parasitic capacitance, which increases when a field plate is disposed inside the gate trench.
Innovation Solution
The semiconductor device incorporates a field plate inside the gate trench, with a fifth insulating portion that includes a first portion inside the field plate and a second portion extending outward, acting as a spacer between the gate electrode and the field plate, to reduce parasitic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a field plate is disposed inside the gate trench to achieve high breakdown voltage and low ON-resistance, then the breakdown voltage and ON-resistance are improved, but the source-gate parasitic capacitance increases
Solution Approach 1:
An insulating film is introduced as an intermediary between the field plate and the gate electrode. This insulating film acts as a mediator that electrically isolates the field plate from the gate electrode, thereby reducing the parasitic capacitance formed between them while maintaining the field plate's voltage-blocking function for high breakdown voltage performance
Solution Approach 2:
The space inside the gate trench is segmented into distinct functional regions: a first region containing the gate electrode and a second region containing the field plate, separated by the insulating film. This segmentation allows each component to perform its function independently while minimizing unwanted electrical interaction between them
Data Source
AI summary
A semiconductor device includes a semiconductor part; first and second electrodes respectively on back and front surfaces of the semiconductor part; third and fourth electrodes inside a trench of the semiconductor part, the fourth electrode being provided between the first electrode and the third electrode; a first insulating portion electrically insulating the third electrode from the semiconductor part; a second insulating portion electrically insulating the third electrode from the second electrode; a third insulating portion electrically insulating the fourth electrode from the semiconductor part; a fourth insulating portion electrically insulating the fourth electrode from the third electrode; and a fifth insulating portion including a first portion and a second portion, the first portion being provided inside the fourth electrode, the second portion extending outward of the fourth electrode. The second portion extends from the first portion in a first direction from the first electrode toward the second electrode.