Work Function Layer Plasma Treatment for FinFET Material Quality
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Solution Overview
Problem
As the minimum feature sizes in semiconductor devices are reduced, challenges arise in forming improved work function layers with high density, reduced grain size, and optimal composition, which are crucial for enhancing device performance and integration density.
Innovation Solution
The process involves depositing a dielectric layer over a semiconductor fin, followed by a work function layer comprising tungsten carbon nitride (WCN). A plasma treatment using helium, nitrogen, and hydrogen gases is applied to the work function layer, increasing its density, reducing carbon concentration, and enhancing nitrogen and tungsten concentrations, thereby improving adhesion and patterning accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If minimum feature sizes are reduced to improve integration density, then more components can be integrated into a given area, but manufacturing precision and material layer quality deteriorate
Solution Approach 1:
The patent applies plasma treatment to change the physical and chemical parameters of the work function layer, including density, grain size, and composition ratios (tungsten, carbon, nitrogen). This transforms the material properties to achieve higher quality despite reduced feature sizes, resolving the contradiction between integration density and manufacturing precision
Solution Approach 2:
The work function layer is formed as a composite material (tungsten carbon nitride) with controlled ratios of multiple elements. This composite structure allows optimization of both density and compositional uniformity, enabling high integration density while maintaining manufacturing precision through controlled material synthesis
2Reliability
If work function layer density is increased to improve device performance, then adhesion and electrical properties improve, but processing complexity increases
Solution Approach 1:
Plasma treatment is applied before subsequent processing steps to pre-condition the work function layer with optimal density and composition. This preliminary action ensures better adhesion and electrical properties from the start, reducing the need for additional corrective processing steps and thereby reducing overall processing complexity
Solution Approach 2:
The patent replaces mechanical deposition methods with plasma-based processing to achieve controlled density and composition in the work function layer. This substitution allows for more precise control of material properties through chemical and physical plasma effects rather than mechanical means, improving device performance while maintaining manageable processing complexity
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 plasma treatment significantly increases the density of the work function layer, reduces grain size, and improves adhesion of subsequent layers, leading to enhanced device performance, reduced defects, and increased yield in semiconductor manufacturing.
Implementation Method 1
exposing the first work function layer to a metastable plasma of a first reaction gas, a metastable plasma of a generation gas, and a metastable plasma of a second reaction gas
Implementation Method 2
exposing the first work function layer to a metastable plasma of a first reaction gas, a metastable plasma of a generation gas, and a metastable plasma of a second reaction gas
Implementation Method 3
exposing the first work function layer to a metastable plasma of a first reaction gas, a metastable plasma of a generation gas, and a metastable plasma of a second reaction gas
Data Source
AI summary
An improved work function layer and a method of forming the same are disclosed. In an embodiment, the method includes forming a semiconductor fin extending from a substrate; depositing a dielectric layer over the semiconductor fin; depositing a first work function layer over the dielectric layer; and exposing the first work function layer to a metastable plasma of a first reaction gas, a metastable plasma of a generation gas, and a metastable plasma of a second reaction gas, the first reaction gas being different from the second reaction gas.