Stepped Contact Plug Structure to Prevent Gate Shorts
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Solution Overview
Problem
The existing semiconductor devices face challenges in preventing electrical shorts between contact plugs and gate structures due to misalignment, which increases the size of the gate structure and affects contact resistance.
Innovation Solution
The semiconductor device incorporates a contact plug design with a lower portion having a first width and an upper portion with a greater width, featuring a stepped lower surface, and is self-aligned with the gate spacer, using etch stop layers and interlayer insulation layers to maintain a sufficient distance from the gate electrode and prevent misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the capping pattern is increased to prevent electrical short between the metal gate electrode and the contact plug, then the reliability is improved, but the size of the gate structure is increased
Solution Approach 1:
The contact plug transitions from a uniform cylindrical shape to a multi-dimensional structure with a wider upper portion and narrower lower portion. This dimensional change allows the contact plug to maintain adequate spacing from the gate electrode in the vertical dimension while reducing the overall gate structure size in the horizontal dimension.
Solution Approach 2:
The contact plug exhibits local quality variation with different widths at different heights. The upper portion has a greater width for stable contact with the source/drain layer, while the lower portion has a narrower width to reduce interference with the gate structure. This localized differentiation resolves the contradiction between reliability and size.
2Manufacturing precision
If the contact plug is self-aligned with the gate spacer to maintain consistent contact area, then the manufacturing precision is improved, but the contact resistance may increase due to misalignment
Solution Approach 1:
The contact plug uses the gate spacer as a self-aligning reference during formation. The etching process automatically positions the contact plug relative to the gate spacer without requiring additional alignment steps, achieving both manufacturing precision and reliable electrical contact.
Solution Approach 2:
The gate spacer is formed beforehand to establish the positional reference for the contact plug. This preliminary structure enables subsequent self-aligned formation of the contact plug, ensuring consistent contact area and low contact resistance while simplifying the manufacturing process.
Data Source
AI summary
A semiconductor device includes a substrate, a gate structure on the substrate, a first etch stop layer, a second etch stop layer, and an interlayer insulation layer that are stacked on the gate structure, and a contact plug penetrating the interlayer insulation layer, the second etch stop layer, and the first etch stop layer and contacting a sidewall of the gate structure. The contact plug includes a lower portion having a first width and an upper portion having a second width. A lower surface of the contact plug has a stepped shape.