Single Diffusion Break Liner for FinFET Gate Structures
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Solution Overview
Problem
In advanced semiconductor technologies, the fabrication of single diffusion breaks for FinFET structures is challenging due to the damage caused by deep trench etch processes, which results in smaller source and drain epitaxial volumes and increased contact resistance, degrading device performance.
Innovation Solution
A method involving the formation of a single diffusion break with a dielectric liner that separates the diffusion regions from the etching process, preserving the epitaxial material and allowing for self-aligned reverse block and wider process windows, while replacing dummy gate structures with metal gate structures to maintain device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a deep trench undercut is provided by removing the dummy gate structure to fabricate a single diffusion break, then the single diffusion break is formed, but the epitaxial source and drain regions are damaged or removed resulting in smaller volume and contact area
Solution Approach 1:
A liner layer is introduced as an intermediary between the etching process and the epitaxial source/drain regions. The liner is selectively removed to define the single diffusion break location while protecting the epitaxial regions from damage, thus preventing increased contact resistance while still achieving the diffusion break
Solution Approach 2:
The liner is formed on the dummy gate structure before the deep trench etch process. This preliminary action establishes a protective barrier that prevents the etching process from damaging the epitaxial source and drain regions, allowing the single diffusion break to be formed without compromising contact quality
2Ease of manufacture
If the source and drain epitaxial volume is reduced due to deep trench undercut damage, then the single diffusion break is achieved, but device performance is degraded
Solution Approach 1:
The liner serves as a protective intermediary during the deep trench etch process, preventing direct contact between the etchant and the epitaxial source/drain regions. This maintains the integrity and volume of the epitaxial regions while still enabling the single diffusion break to be formed through selective liner removal
3Ease of manufacture
If dummy gate structures are used to induce symmetrical epitaxial growth, then the source and drain regions are formed, but the gate height budget is increased due to boundary-induced issues
Solution Approach 1:
The gate structure is changed from a conventional polysilicon-based dummy gate to a metal gate structure. This parameter change in material composition eliminates the boundary-induced issues that consume gate height budget, while the metal gate still provides the necessary function of inducing symmetrical epitaxial growth during the source/drain formation process
Data Source
AI summary
The present disclosure relates to semiconductor structures and, more particularly, to a single diffusion cut for gate structures and methods of manufacture. The structure includes: a plurality of fin structures; a plurality of gate structures extending over the plurality of fin structures; a plurality of diffusion regions adjacent to the each of the plurality of gate structures; a single diffusion break between the diffusion regions of the adjacent gate structures; and a liner separating the single diffusion break from the diffusion regions.