Metal Ion Capture Layer Between Adjoining FinFET Gates
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Solution Overview
Problem
As semiconductor devices scale down, metal gates with different work function metals (WFMs) adjoining each other lead to metal diffusion and migration, causing leakage current and reducing device performance.
Innovation Solution
Incorporating a metal ion capture layer, such as a fluorine-rich oxide layer or a layer with carbon, nitrogen, phosphorous, arsenic, antimony, and fluorine, within the interlayer dielectric layer or metal fill layer to react with diffused metal ions, thereby reducing metal drifting and migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If metal gates with different work function metals are placed adjacent to each other to achieve higher storage capacity and faster processing, then device density and performance are improved, but metal diffusion and migration occur causing leakage current
Solution Approach 1:
A metal ion capture layer is introduced as an intermediary between adjacent metal gates with different work function metals. This capture layer, containing elements such as carbon, nitrogen, phosphorous, arsenic, antimony, and fluorine, acts as a mediator that traps migrating metal ions and prevents them from causing leakage current, thereby resolving the contradiction between high device density and low leakage current.
Solution Approach 2:
The metal ion capture layer is formed in advance within the interlayer dielectric layer or metal fill layer before the metal diffusion problem occurs. By pre-positioning the capture layer with reactive elements, the system is prepared to immediately trap any metal ions that attempt to migrate between adjacent gates, preventing the harmful effect before it can manifest.
2Adaptability or versatility
If metal gates with different work function metals are used to meet increasing demand for higher performance, then device functionality is enhanced, but metal diffusion between gates increases
Solution Approach 1:
The metal ion capture layer serves as a stabilizing intermediary that maintains the compositional stability of adjacent metal gates. By containing elements with high affinity for metal ions, the capture layer prevents intermixing and diffusion between different work function metals, thereby preserving the intended functionality and composition stability simultaneously.
3Productivity
If device dimensions are scaled down to increase transistor density, then storage capacity increases, but metal migration becomes more significant
Solution Approach 1:
As device dimensions are scaled down, the metal ion capture layer becomes increasingly critical as a protective intermediary. The capture layer, positioned within the interlayer dielectric or metal fill, provides a localized barrier that is proportionally effective at the smaller scale, trapping metal ions before they can migrate significant distances and compromise device performance.
Solution Approach 2:
The metal ion capture layer is strategically positioned in specific locations where metal migration is most likely to occur, such as within the interlayer dielectric layer or metal fill layer adjacent to gate structures. This localized placement ensures that the capture layer provides targeted protection precisely where the harmful metal migration effect is most problematic.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The metal ion capture layer effectively reduces leakage current and improves device performance by minimizing metal diffusion between adjoining metal gates with different WFMs.
Implementation Method 1
forming a metal ion capture layer... to react with diffused metal ions, thereby reducing metal drifting and migration
Data Source
AI summary
The present disclosure describes a semiconductor structure with a metal ion capture layer and a method for forming the structure. The method includes forming a first fin structure and a second fin structure on a substrate and forming a first gate structure over the first fin structure and a second gate structure over the second fin structure, where the first gate structure adjoins the second gate structure. The method further includes forming a dielectric layer on the first and second gate structures, removing a portion of the dielectric layer above an adjoining portion of the first and second gate structures to form an opening, and forming a metal ion capture layer in the opening.