Gate Refill Metal Dielectric Liner for GAA Isolation Reliability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
As the scale of fin width in fin field effect transistors (FinFETs) decreases, channel width variations can cause mobility loss, and in GAA transistors, reducing gate-to-gate pitch by forming thinner gate spacers increases the risk of isolation breakdown between the metal gate and source/drain contact.
Innovation Solution
An additional dielectric liner is formed before the gate refill metal is deposited, increasing the distance between the gate refill metal and the source/drain contact, thereby reducing the risk of isolation breakdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If gate spacers are made thinner to reduce gate-to-gate pitch in GAA transistors, then device integration density is improved, but the risk of isolation breakdown between metal gate and source/drain contact increases
Solution Approach 1:
A dielectric liner is introduced as an intermediary layer between the gate refill metal and the source/drain contact. This liner acts as a protective barrier that prevents direct contact and potential breakdown, while allowing the gate spacer thickness to be reduced for higher integration density. The dielectric liner effectively mediates the interaction between the metal gate and source/drain regions.
Solution Approach 2:
The dielectric liner is formed beforehand before depositing the gate refill metal, creating a protective cushion layer in advance. This pre-formed liner provides isolation protection before the metal gate structure is completed, preventing potential breakdown paths from forming during subsequent processing steps.
2Reliability
If additional dielectric liner is formed before gate refill metal deposition, then isolation reliability is improved, but device complexity increases
Solution Approach 1:
The dielectric liner is formed as a preliminary step before gate refill metal deposition. By performing this isolation-enhancing action early in the gate formation sequence, the subsequent metal deposition and patterning steps become simpler and more reliable, as the liner is already in place to guide and protect the process.
Data Source
AI summary
A device includes a gate structure, first and second gate spacers, source/drain regions, a refill metal structure, and a first dielectric liner. The gate structure is on a substrate. The first and second gate spacers are on opposite sides of the gate structure, respectively. The source/drain regions are spaced part from the gate structure at least in part by the first and second gate spacers. The refill metal structure is on the gate structure and between the first and second gate spacers. The first di electric liner is atop the gate structure. The first dielectric liner interposes the refill metal structure and the first gate spacer.