Trench Gate Semiconductor Structure for Avalanche Field Relaxation
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Solution Overview
Problem
The electric field applied to the electric field protection layer at the ends of gate trenches in active regions experiences a higher stress, leading to a decrease in avalanche breakdown voltage, and existing configurations either require increased depth and thickness of floating regions or lack effective electric field relaxation in the active region.
Innovation Solution
A semiconductor device with an electric field relaxation layer between the active and termination regions, where the bottom surface of the relaxation layer is shallower than the protection layer and electrically connected to the P body layer, effectively reducing the electric field curvature and improving avalanche breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an electric field protection layer is provided at the bottom of gate trenches in the active region, then the gate insulating film is protected against large current and voltage, but the electric field applied to the protection layer at the ends of the active region becomes excessively large, causing a decrease in avalanche breakdown voltage
Solution Approach 1:
An electric field relaxation layer is introduced as an intermediary structure between the active region and termination region. This layer has a shallower bottom surface than the electric field protection layer and is electrically connected to the P body layer, serving as a mediator to redistribute and relax the concentrated electric field at the gate trench ends, thereby preventing avalanche breakdown while maintaining the protective function of the original electric field protection layer
2Object-affected harmful factors
If floating regions are provided in the termination area to relax the electric field, then the electric field distribution is improved, but the manufacturing complexity increases due to the need to precisely control the depth and thickness of the floating regions
Solution Approach 1:
The electric field relaxation layer is positioned specifically at the gate trench ends where the electric field concentration problem occurs, rather than uniformly throughout the termination region. The layer has localized shallower depth compared to the electric field protection layer, creating different structural qualities in different spatial locations to address the local electric field issue without requiring complex global modifications
Solution Approach 2:
The electric field relaxation layer is formed with a shallower bottom surface than the electric field protection layer before final device operation. This preliminary structural arrangement pre-distributes the electric field in a more favorable pattern, preventing excessive field concentration at the gate trench ends before high-voltage stress is applied, thereby simplifying subsequent manufacturing steps
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 semiconductor device relaxes the electric field applied to the protection layer at the ends of active regions, enhancing the avalanche breakdown voltage while being easily manufacturable.
Implementation Method 1
a larger electric field is likely to be applied to the electric field protection layer of the gate trenches arranged at ends of the active region than in other portions
Data Source
AI summary
Provided is a semiconductor device where an electric field applied to an electric field protection layer at a bottom of a trench gate electrode of an active region is relaxed and an avalanche withstand voltage is improved. The semiconductor device includes: an active region that has multiple gate trenches, a trench gate electrode in each gate trench, and a P body layer provided to a section other than the gate trenches; and a termination region disposed on the outer periphery of the active region. Additionally, an electric field protection layer is provided to the bottom of each gate trench of the active region, an electric field relaxation layer is between the active region and the termination region, the bottom surface of the electric field relaxation layer is shallower than that of the electric field protection layer, and the electric field relaxation layer is electrically connected to the P body layer.