Mesa Contact Plug Structure for Narrow-Trench Power Semiconductors
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Solution Overview
Problem
As the width of the mesa in power semiconductor devices becomes smaller, it becomes more difficult to reliably contact the mesa using a contact plug structure.
Innovation Solution
The implementation of a protection structure between the contact plug and the trench electrode of the first trench allows for a reliable contact with the mesa, even with a small mesa width, by providing electrical insulation and enabling a shared contact scheme where the trench electrode adjacent to the mesa is not connected to the emitter potential but to another potential like the gate potential.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the mesa width is reduced, then the device integration density is improved, but the reliability of contact plug structure deteriorates
Solution Approach 1:
The patent introduces a protection structure as an intermediary element between the contact plug and the trench electrode. This protection structure, formed by depositing dielectric material and selectively removing portions, acts as a mediator that enables the contact plug to reliably contact the mesa region even when the mesa width is reduced. The protection structure provides mechanical support and electrical isolation, allowing the contact plug to bridge across the narrowed mesa width without compromising contact reliability.
2Area of moving object
If the mesa width is reduced, then the device integration density is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent segments the contact structure into distinct functional components: the contact plug, the protection structure, and the trench electrode. The protection structure itself is segmented through selective removal of dielectric material in specific regions. This segmentation allows each component to be optimized independently - the contact plug for electrical connection, the protection structure for isolation and support, and the trench electrode for field control - thereby managing the overall complexity while enabling reduced mesa width.
3Reliability
If a protection structure is added, then the contact reliability with small mesa width is improved, but the device complexity increases
Solution Approach 1:
The protection structure serves multiple functions simultaneously: it provides electrical isolation between the contact plug and trench electrode, mechanical support for the contact plug structure, and defines the lateral boundaries of the contact region. By consolidating these multiple functions into a single structural element formed through standard semiconductor processing steps (dielectric deposition and selective removal), the patent improves contact reliability without proportionally increasing device complexity.
Data Source
AI summary
A power semiconductor device includes: a semiconductor body having a first surface and a mesa portion that includes a surface part of the first surface and a body region; at least two trenches extending from the first surface into the semiconductor body along a vertical direction, each trench including a trench electrode and trench insulator insulating the trench electrode from the semiconductor body, the mesa portion being laterally confined by the trenches in a first vertical cross-section along a first lateral direction; and a contact plug in contact with the body region. The contact plug and trench electrode of a first trench laterally overlap at least partially in the first vertical cross-section. A protection structure having a portion arranged within the first trench is arranged between the contact plug and trench electrode of the first trench. The protection structure may be an electrically insulation structure or a protective device structure.