Trench Insulating Plug Structure for Higher MOSFET Breakdown Voltage
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Solution Overview
Problem
Current semiconductor devices, such as MOSFETs, face challenges in improving performance and preventing breakdown due to edge effects, particularly in power electronic applications where trench structures and edge termination regions play a crucial role.
Innovation Solution
A semiconductor device is designed with a trench in the edge termination region filled with an electrically insulating plug and layer, where the plug extends across the trench width and forms an interface with the insulating layer, enhancing insulation and preventing material penetration during processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a trench is filled with electrically insulating material in the edge termination region, then breakdown voltage is increased and edge effects are reduced, but device complexity increases due to additional insulating layers and interfaces
Solution Approach 1:
The electrically insulating material in the trench is segmented into two distinct parts: a first electrically insulating layer that lines the trench walls and base, and a second electrically insulating plug that fills the remaining space. This segmentation allows each layer to perform its specific function optimally while maintaining overall reliability and managing complexity through functional division.
2Reliability
If the insulating plug extends across the entire trench width, then insulation effectiveness is improved, but manufacturing precision requirements increase due to interface formation constraints
Solution Approach 1:
The first electrically insulating layer is formed preliminarily to line the trench walls and base before the second electrically insulating plug is deposited. This preliminary action creates a prepared substrate that facilitates subsequent plug formation and reduces precision requirements by providing a pre-established interface geometry.
Solution Approach 2:
The first electrically insulating layer acts as an intermediary between the trench structure and the second electrically insulating plug. It provides a transition zone that simplifies interface formation and reduces manufacturing precision requirements by mediating the connection between the trench walls and the fill material.
3Reliability
If the upper surface of the plug is coplanar with the semiconductor substrate surface, then device performance is improved, but additional processing steps are required
Solution Approach 1:
The requirement for coplanar surfaces is addressed by considering the vertical dimension and using chemical mechanical polishing to remove excess material and achieve the desired surface alignment. This dimensional approach transforms a complex multi-step alignment problem into a more manageable surface finishing operation.
Data Source
AI summary
In an exemplary embodiment, a semiconductor device includes: a semiconductor substrate having a first major surface; a trench positioned in the semiconductor substrate and having a width, a base, and a side wall extending from the base to the first major surface; a first electrically insulating layer that lines the base and the side wall of the trench; and an electrically insulating plug that is positioned in the trench and that extends across the entire width of the trench. The plug has a lower surface that forms an interface with the first electrically insulating layer and an upper surface. The upper surface of the plug is coplanar with the first major surface of the semiconductor substrate or positioned within the trench.