Stacked Nanosheet Gate Structure for Dummy Gate Etch Protection
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Solution Overview
Problem
In the etching process for the dummy gate in semiconductor devices, the topmost active channel sheet is prone to damage due to its exposed position.
Innovation Solution
The implementation of a first active structure with a plurality of first active channel sheets and first metal gate structures vertically stacked, where the topmost first metal gate structure covers the topmost active channel sheet, and a first helmet formed above the topmost first inner spacer to cover the lateral surface of the conductive portion, thereby protecting the topmost active channel sheet during the etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the topmost active channel sheet is left exposed for etching access, then the etching process can be performed, but the active channel sheet is damaged
Solution Approach 1:
A protective layer is formed over the active channel sheet before the etching process begins. This preliminary protective action allows the etching to proceed while the active channel sheet remains protected, preventing damage that would otherwise occur from direct exposure to the etching process.
Solution Approach 2:
The protective layer acts as an intermediary between the etching process and the active channel sheet. It allows the etching to access and remove the dummy gate material while preventing the harmful etching chemicals from directly contacting and damaging the active channel sheet.
2Reliability
If the topmost active channel sheet is covered to protect it, then the active channel sheet is protected from damage, but the etching process cannot access the dummy gate
Solution Approach 1:
The protective layer is applied selectively - it covers the active channel sheet to provide protection where needed, but is configured to allow etching access to the dummy gate regions. This local differentiation of protective quality enables simultaneous protection of vulnerable areas and accessibility of areas requiring etching.
Solution Approach 2:
The protective structure is segmented or patterned rather than being a complete continuous cover. This segmentation allows different regions to have different properties - some areas provide protection while other areas allow etching access, enabling both protection and manufacturability.
Data Source
AI summary
A semiconductor device includes a substrate, a first active structure, a conductive portion and a first helmet. The first active structure is formed on the substrate and includes a plurality of first active channel sheets and a plurality of first metal gate structures vertically stacked to each other, wherein the topmost first metal gate structure includes a first inner spacer. The conductive portion is connected with the topmost first active channel sheet. The first helmet is formed above the first inner spacer and covers a lateral surface of the conductive portion.