Bidirectional MOSFET Body Contact Plug for Snapback Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing bidirectional trench FET devices suffer from bipolar snapback due to high resistive paths in the P-body, leading to low blocking voltage and limited safe operating area, as they are inefficient in removing holes generated by impact ionization near the drain and body junction.
Innovation Solution
Incorporating body contact plugs made from materials like tungsten, surrounded by a dielectric lining to isolate them from the source region, and using two separate metal layers for multiple body and source contacts, which creates low resistive paths to suppress bipolar snapback and maintain bidirectional switching capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a P+ link connects the P-region body to the P-body electrode, then the process is readily implementable, but the high resistive path fails to efficiently remove holes generated by impact ionization
Solution Approach 1:
The patent changes the electrical parameters of the body region by introducing heavily doped P+ regions and body contact plugs, transforming the high-resistive P-body into a low-resistive structure. This parameter change enables efficient hole removal while maintaining manufacturability through standard doping and metallization processes.
Solution Approach 2:
The patent introduces body contact plugs as intermediary elements between the P-region body and the P-body electrode. These plugs act as mediators that provide low-resistive pathways for hole extraction, resolving the contradiction between easy manufacturing and reliable high-voltage blocking by adding a intermediate structural element.
2Device complexity
If the P-body has a high resistive path, then the structure is simple, but bipolar snapback occurs at lower impact ionization resulting in limited safe operating area
Solution Approach 1:
The patent applies local quality by creating heavily doped P+ regions in specific locations (body contact regions) while maintaining the overall P-body structure. This localized modification provides low-resistive pathways where needed without fundamentally changing the entire device structure, thus suppressing bipolar snapback while keeping the device relatively simple.
Solution Approach 2:
The patent segments the body contact path into multiple components: P+ doped regions, body contact plugs, and connections to the P-body electrode. This segmentation allows each component to be optimized independently for its specific function, achieving low overall resistance without requiring complete structural redesign.
3Adaptability or versatility
If body contact plugs are isolated from the source region, then bidirectional switching capability is maintained, but the structure becomes more complex
Solution Approach 1:
The patent extracts the body contact function from the source region by creating isolated body contact plugs that are dielectrically lined and electrically separated from the source. This extraction allows independent optimization of body contact resistance without affecting source region functionality, maintaining bidirectional switching while managing complexity through functional separation.
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 solution effectively suppresses bipolar snapback, enhancing the blocking voltage and safe operating area of bidirectional trench FET devices by efficiently removing holes generated by impact ionization, thereby improving their performance in high current and voltage applications.
Implementation Method 1
holes generated by impact ionization near the drain and body junction
Implementation Method 2
low resistive paths formed by the body contact plugs
Data Source
AI summary
A bidirectional trench FET device includes a semiconductor substrate, a trench in the substrate extending vertically from the surface of the substrate, and a body region laterally adjacent the trench. A source region is disposed in the semiconductor substrate between the body region and the surface of the substrate. A dielectric layer is disposed over the surface and a body electrode is disposed over the dielectric layer. A body contact plug extends through the dielectric layer to interconnect the body region with the body electrode, and the body contact plug is electrically isolated from the source region. Two separate metal layers are implemented to make multiple body and source contacts electrically isolated from one another throughout the active area of the device. The low resistive path by the body contact plug and the separate metal layers enables suppression of bipolar snapback without losing bidirectional switching capability.