Insulated Gate Semiconductor Device Bidirectional Switching
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Solution Overview
Problem
Conventional insulated gate semiconductor devices face limitations in miniaturization and bidirectional switching due to parasitic diodes forming unwanted current paths, especially in protection circuits for secondary batteries, where series-connected MOSFETs are required to manage charge and discharge, but this configuration is not efficient for miniaturization demands.
Innovation Solution
The design separates the back gate electrode from the source electrode, allowing individual control of potentials for source and back gate regions, enabling bidirectional switching in a single MOSFET chip by using a semiconductor substrate with trenches, gate electrodes, and distinct back gate regions, which prevents unwanted current paths and reduces on-resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If series-connected MOSFETs are used for bidirectional switching in protection circuits, then bidirectional switching capability is achieved, but device complexity and chip area increase
Solution Approach 1:
The patent combines two separate MOSFETs into a single MOSFET device by integrating two channel layers with different conductivity types within one chip. The first channel layer (first conductivity type) and second channel layer (second conductivity type) are formed in the same semiconductor substrate, sharing common structures such as the semiconductor substrate, drain region, and interlayer insulating film. This merging achieves bidirectional switching capability while reducing device complexity and chip area compared to using two separate MOSFETs.
2Adaptability or versatility
If series-connected MOSFETs are used for bidirectional switching, then bidirectional current control is achieved, but on-resistance increases
Solution Approach 1:
By merging two MOSFETs into one device with shared substrate and drain region, the patent reduces the total on-resistance compared to series-connected separate MOSFETs. The common drain region and substrate provide low-resistance current paths for both current directions, reducing energy loss while maintaining bidirectional current control capability.
Solution Approach 2:
The patent employs different conductivity types in different channel layers (first channel layer with first conductivity type, second channel layer with second conductivity type) to optimize local electrical properties. This allows each channel layer to be optimized for specific current directions, reducing overall on-resistance while maintaining bidirectional control.
3Ease of manufacture
If body regions and source regions are common-connected to source electrode, then manufacturing is simplified, but parasitic diodes form unwanted current paths
Solution Approach 1:
The patent segments the electrode connections by providing separate source electrodes for the first source region and second source region. The first source electrode connects to the first source region, and the second source electrode connects to the second source region. This segmentation prevents the formation of unwanted current paths through parasitic diodes that would occur if body regions and source regions were common-connected, while still maintaining manufacturing feasibility.
Data Source
AI summary
Provided is an insulated gate semiconductor device. In the device, source regions are provided in the entire operation area and a first back gate region is provided below the source region between trenches. Moreover, a second back gate region connected to the first back gate region is provided outside of the source regions. Thereafter, a first electrode layer coming into contact with the source regions is provided in the entire operation area, and a second electrode layer coming into contact with the second back gate regions is provided around the first electrode layer. Accordingly, potentials can be individually applied to the first electrode layer and the second electrode layer. Thus, it is possible to perform control for preventing reverse flow caused by a parasitic diode.