Trench Gate Switching Structure With Pre-Implanted Field Relaxation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing switching devices with trench-type gate electrodes face challenges in accurately positioning the electric field relaxation region, leading to misalignment and variations in breakdown voltage and on-resistance due to limitations in photolithography alignment and gate trench depth variations.
Innovation Solution
A method for manufacturing a switching device that forms the electric field relaxation region before the gate trench, ensuring high positional accuracy by implanting p-type impurities through a mask opening, and then etching the gate trench to maintain the relaxation region below it, thereby suppressing lateral misalignment and vertical position variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the electric field relaxation region is formed after the gate trench using conventional photolithography alignment, then the manufacturing process follows conventional sequencing, but lateral misalignment occurs between the relaxation region and gate trench leading to variations in breakdown voltage and on-resistance
Solution Approach 1:
The electric field relaxation region is formed by implanting p-type impurities into the drift region before the gate trench is etched. This preliminary formation ensures that the relaxation region is positioned with high precision relative to the subsequent gate trench location, eliminating lateral misalignment issues that would occur with conventional post-trench formation methods.
2Adaptability or versatility
If the gate trench depth is varied to accommodate different device requirements, then device versatility is improved, but the vertical position of the relaxation region varies leading to inconsistent electrical characteristics
Solution Approach 1:
The relaxation region is formed before the gate trench etching process, establishing its vertical position independently of the final trench depth. This allows the gate trench depth to be varied for different device specifications while the relaxation region maintains consistent positioning in the drift region, ensuring uniform electrical characteristics across different device configurations.
Solution Approach 2:
Instead of forming the relaxation region at the bottom of the gate trench (which would tie its position to trench depth variations), the method inverts the sequence by forming the relaxation region in the drift region first, then etching the gate trench above it. This inversion decouples the relaxation region's vertical position from the gate trench depth, maintaining consistency despite depth variations.
3Ease of manufacture
If the relaxation region is formed by implanting impurities after gate trench formation, then the process sequencing is conventional, but the bottom end of the relaxation region may protrude from the gate trench causing electric field concentration
Solution Approach 1:
The relaxation region is formed before the gate trench is etched, ensuring that the region is contained within the area that will become the gate trench footprint. This preliminary formation prevents the bottom end of the relaxation region from protruding beyond the gate trench, thereby eliminating electric field concentration at the trench bottom and improving device reliability.
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
This approach effectively suppresses electric field concentration near the gate trench bottom, maintaining high breakdown voltage and reducing on-resistance by ensuring precise alignment and consistent relaxation region positioning.
Implementation Method 1
forming the electric field relaxation region in the drift region by implanting a p-type impurity into the semiconductor substrate through the opening
Implementation Method 2
forming the gate trench by etching the upper surface of the semiconductor substrate within the opening of the mask
Data Source
AI summary
A method for manufacturing a switching device includes: forming a source region and a body region in a semiconductor substrate having a drift region; forming a mask having an opening on an upper surface of the semiconductor substrate having the drift region; after the forming of the mask, forming an electric field relaxation region in the drift region by implanting a p-type impurity into the semiconductor substrate through the opening; after the forming of the electric field relaxation region, forming a gate trench by etching the upper surface of the semiconductor substrate within the opening of the mask so that the electric field relaxation region remains below the gate trench; and after the forming of the gate trench, forming a gate insulating film and a gate electrode in the gate trench.