FinFET Gate Spacer Reshaping for Lower Gate Resistance
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Solution Overview
Problem
The semiconductor industry faces challenges in reducing gate resistance (Rg) of FinFETs due to difficulties in fully depositing materials around metal gates, particularly in dense regions where dummy gate replacement is complex, leading to gaps or voids that increase resistance.
Innovation Solution
A spacer treatment process is applied to gate spacers, causing them to bow inward, which allows for more complete deposition of metal gates and reduces the formation of gaps or voids, thereby decreasing gate resistance by enabling better material deposition and contact with the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional metal gate deposition is performed without spacer treatment, then the deposition process is simpler, but gaps or voids form around metal gates increasing gate resistance
Solution Approach 1:
The gate spacers are treated with a spacer treatment process before metal gate deposition to pre-condition their surfaces. This preliminary action modifies the spacer surfaces to promote complete material deposition, preventing gaps or voids from forming during subsequent metal gate deposition, thereby reducing gate resistance without complicating the overall process
Solution Approach 2:
The spacer treatment process acts as an intermediary step between conventional deposition processes and the metal gate formation. This intermediate treatment modifies the spacer surfaces to serve as better templates for complete material deposition, enabling full coverage around metal gates and reducing gate resistance
2Productivity
If dummy gate replacement is performed in dense regions, then integration density is maintained, but complete material deposition becomes difficult leading to voids
Solution Approach 1:
In dense regions where dummy gate replacement is necessary, the spacer treatment process is applied beforehand to pre-condition the spacer surfaces. This preliminary modification ensures that subsequent material deposition can completely cover the complex geometries in dense regions, preventing voids while maintaining integration density
Solution Approach 2:
The spacer treatment process is particularly important in dense regions where local geometry challenges prevent complete material deposition. By locally treating the spacer surfaces in these challenging areas, the process enables complete coverage where it is most needed, maintaining both integration density and deposition completeness
Data Source
AI summary
In an embodiment, a device includes: a first fin extending from a substrate; a second fin extending from the substrate; a gate spacer over the first fin and the second fin; a gate dielectric having a first portion, a second portion, and a third portion, the first portion extending along a first sidewall of the first fin, the second portion extending along a second sidewall of the second fin, the third portion extending along a third sidewall of the gate spacer, the third portion and the first portion forming a first acute angle, the third portion and the second portion forming a second acute angle; and a gate electrode on the gate dielectric.