Self-Aligned Gate Contact Layout for Nanosheet Short Prevention
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Solution Overview
Problem
As the semiconductor industry moves towards smaller node sizes, such as the 3-nm node and beyond, the increasing device density leads to concerns about potential shorts between source/drain contacts and the gate contact in nanosheet transistors due to the reduced space for forming these contacts.
Innovation Solution
A semiconductor structure is developed with a gate structure having a first portion with a higher top surface and a second portion with a lower top surface, where the first portion is embedded in a dielectric cap layer. A gate contact is formed above and aligned with the first portion of the gate structure, and source/drain contacts are positioned adjacent to the gate structure with appropriate spacers to prevent shorts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If device density is increased to fit transistors into reduced footprint, then productivity is improved, but reliability deteriorates due to potential shorts between source/drain contacts and gate contact
Solution Approach 1:
The gate contact structure is segmented into two distinct portions: a first portion extending over the source/drain contact region and a second portion extending over the gate electrode region. This segmentation allows the gate contact to be electrically isolated from the source/drain contact by the gate electrode, preventing shorts while maintaining high device density
Solution Approach 2:
The gate electrode serves as an intermediary element between the source/drain contact and the gate contact. The gate contact's second portion contacts the gate electrode, which in turn is positioned between the gate contact and the source/drain contact, providing electrical isolation and preventing direct contact that would cause shorts
2Volume of moving object
If space for forming contacts is reduced due to scaling, then device footprint is reduced, but manufacturing precision must be increased to avoid shorts
Solution Approach 1:
The gate contact structure merges multiple functions into a single continuous conductive element: the first portion provides electrical connection to the source/drain contact, the second portion provides electrical connection to the gate electrode, and the gate electrode itself provides electrical isolation. This merging reduces the number of separate components and alignment steps required, thereby reducing manufacturing complexity and precision requirements while maintaining compact dimensions
Data Source
AI summary
Embodiments of present invention provide a semiconductor structure. The semiconductor structure includes a gate structure with a first portion having a first top surface and a second portion having a second top surface, the first top surface being above the second top surface; a dielectric cap layer on top of the second portion of the gate structure, the first portion of the gate structure being embedded in the dielectric cap layer; and a gate contact being above and substantially aligned with the first portion of the gate structure. A method of forming the same is also provided.