L-Shaped Mesa Contact Plug for Power Semiconductor Reliability
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Solution Overview
Problem
As the width of the mesa in power semiconductor devices decreases, it becomes increasingly difficult to reliably contact the mesa using a contact plug structure, which is essential for the proper functioning of these devices in applications like power converters and electric motor driving.
Innovation Solution
The solution involves a power semiconductor device design where the contact plug extends along the entire top width of the mesa, interfacing with both the source and body regions, and is formed by depositing an electrically conductive material after creating an elevated source bridge between adjacent trenches, ensuring reliable contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the mesa width is reduced, then the device performance is improved, but the reliability of contact plug structure deteriorates
Solution Approach 1:
The contact plug transitions from a traditional vertical structure to an L-shaped structure that extends laterally along the mesa top surface. This dimensional change allows the contact plug to span the entire mesa width while maintaining vertical contact functionality, enabling reliable contact even as mesa width decreases.
Solution Approach 2:
The contact plug is designed to extend laterally along the mesa top surface before making vertical contact. This preliminary lateral extension ensures that the contact plug establishes electrical connection with both source and body regions before penetrating into the semiconductor body, pre-establishing reliable contact paths.
2Productivity
If the mesa width is reduced, then the device integration is improved, but the manufacturing difficulty increases
Solution Approach 1:
The contact plug adopts an L-shaped geometry with both lateral and vertical components. This dimensional transformation simplifies the manufacturing process by allowing the contact plug to be formed in two distinct stages: first laterally along the mesa surface, then vertically into the semiconductor body, rather than requiring precise single-step formation in narrow spaces.
Solution Approach 2:
The contact plug formation process is segmented into two functional parts: a lateral portion extending along the mesa top surface to contact source and body regions, and a vertical portion penetrating into the semiconductor body. This segmentation allows each part to be optimized and manufactured independently, reducing overall manufacturing complexity.
Data Source
AI summary
A power semiconductor device includes: a semiconductor body with a drift region; a plurality of trenches, wherein two adjacent trenches laterally confine a mesa of the semiconductor body. Each trench extends along a vertical direction and includes a trench electrode, and has a trench width along a first lateral direction and a trench length along a second lateral direction perpendicular to the first lateral direction, the trench length amounting to at least five times the trench width. The device further includes: a semiconductor body region of a second conductivity type in the mesa; a source region in the mesa; an insulation layer above and/or on the source region; a contact plug that extends at least from an upper surface of the insulation layer along the vertical direction so as to contact both the source region and the semiconductor body region.