Source Trench Contact Structure for Stable Semiconductor Switching
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Solution Overview
Problem
Existing semiconductor devices face challenges in maintaining consistent characteristics due to displacement of source contact plugs, which affects gate threshold voltage and on resistance, and require improved inductive load resistance and switching speed.
Innovation Solution
The semiconductor device incorporates source contact plugs that contact the embedded electrode via the side wall of the source trench, with a lower extension and overhanging portions to ensure alignment and deep positioning, and includes field plate electrodes to manage electric field concentration and impurity concentration for reduced on resistance and increased switching speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If source contact plugs are formed using conventional methods, then manufacturing process is simpler, but displacement of source contact plugs occurs causing variations in device characteristics
Solution Approach 1:
The source contact plug is divided into multiple segments: an upper portion, a lower extension portion, and overhanging portions. This segmentation allows each part to serve a specific function - the lower extension anchors to the source region while the overhanging portions provide alignment reference, collectively improving positioning precision without requiring complete redesign of the entire device structure.
Solution Approach 2:
The source trench is formed and the lower extension portion of the source contact plug is positioned in advance before final plug formation. This preliminary positioning establishes a reference framework that guides subsequent manufacturing steps, ensuring accurate alignment of the source contact plug with the source region and preventing displacement during later processing.
2Productivity
If gate trench and source contact hole are arranged alternately, then device integration is achieved, but source contact plug displacement affects gate threshold voltage and on resistance
Solution Approach 1:
The side wall of the source trench acts as an intermediary reference structure between the gate trench and the source contact plug. By forming the lower extension portion along this side wall, the invention creates a stable reference that mediates the spatial relationship between alternating structures, ensuring consistent positioning even in high-density integrated layouts.
Solution Approach 2:
The source contact plug exhibits local quality variations with different portions having distinct functions and geometries. The lower extension portion has a specific shape optimized for anchoring, while overhanging portions extend laterally for alignment. This localized differentiation allows the plug to maintain precise positioning in the alternating trench arrangement without compromising overall device integration.
3Speed
If field plate electrode is added to manage electric field, then on resistance decreases and switching speed increases, but device structure becomes more complex
Solution Approach 1:
The field plate electrode is integrated with existing device structures to perform multiple functions simultaneously. It serves both as an electric field management element to reduce on-resistance and as a structural component that can be formed using the same manufacturing processes as other electrodes, thereby improving switching speed without proportionally increasing device complexity.
Data Source
AI summary
A semiconductor device includes a semiconductor layer including a first surface and a second surface opposite to the first surface; a source trench formed in the semiconductor layer and including a side wall that is continuous with the second surface; an insulation layer formed on the second surface of the semiconductor layer; an embedded electrode arranged in the source trench and insulated from the side wall of the source trench by the insulation layer; a source interconnection formed on the insulation layer; and a source contact plug electrically connecting the source interconnection to the semiconductor layer. The source contact plug contacts the embedded electrode, and the source contact plug contacts the semiconductor layer via a part of the side wall of the source trench.