Semiconductor Contact Plug Bottom Surface Configuration
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Solution Overview
Problem
In semiconductor device manufacturing, the over-etching of insulating interlayers can lead to electrical failures due to the second contact plug contacting the substrate, causing leakage current and reliability issues.
Innovation Solution
A semiconductor device design where the second contact plug has a specific bottom surface configuration, including a first portion not contacting the upper surface of the first contact plug and a convex or concave portion adjacent to it, with a barrier pattern and insulation layer structure to prevent substrate contact, ensuring reliable electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the insulating interlayer is over-etched to form the opening for the second contact plug, then the opening can be fully formed to contact the gate structure, but the substrate surface may be exposed causing leakage current and electrical failure
Solution Approach 1:
The patent applies preliminary action by forming a protective insulation layer structure (comprising first and second insulation layers) on the substrate surface before the etching process. This pre-formed structure prevents the etchant from reaching and exposing the substrate surface, thereby avoiding leakage current while still allowing the second contact plug to be formed with proper electrical connection to the gate structure.
Solution Approach 2:
The patent introduces an intermediary protective insulation layer structure between the etchant and the substrate surface. This intermediate layer acts as a barrier that prevents direct contact between the over-etched insulating interlayer and the substrate, eliminating the harmful effect of substrate exposure while maintaining the functionality of the second contact plug.
2Reliability
If the second contact plug is formed to contact both the gate structure and the first contact plug, then good electrical connection is achieved, but the complex bottom surface configuration increases manufacturing difficulty
Solution Approach 1:
The patent segments the bottom surface of the second contact plug into distinct functional regions: a protective insulation layer contact region and a metal pattern region. This segmentation allows the different portions to serve different purposes - the insulation layer provides protection while the metal pattern establishes electrical connection, simplifying the overall manufacturing process by clearly defining fabrication steps for each region.
Solution Approach 2:
The patent applies local quality by giving different portions of the second contact plug bottom surface different properties and functions. The first portion contacts the protective insulation layer for protection, while the convex portion makes selective contact with either the gate structure or first contact plug depending on the specific design, optimizing electrical connection at each location without requiring complex overall structure.
Data Source
AI summary
A semiconductor device includes a gate structure on a substrate, a source/drain layer on a portion of the substrate adjacent the gate structure, a first contact plug contacting an upper surface of the source/drain layer, and a second contact plug contacting upper surfaces of the gate structure and the first contact plug. A bottom surface of the second contact plug has a first portion not contacting the upper surface of the first contact plug, and the first portion is higher than the upper surface of the gate structure.