Plasma Densification of Semiconductor Barrier Layers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The reduction of barrier layer thickness in semiconductor devices due to scaling and the incorporation of non-planar geometries leads to plasma penetration into underlying metal layers during plasma densification, affecting device performance and resistivity.
Innovation Solution
A plasma densification process applying power of 300 W or less to the densification plasma, which reduces barrier layer thickness while maintaining underlying layer integrity and allowing tunability, thereby reducing nitrogen penetration into the underlying metal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the barrier layer thickness is reduced to allow sufficient metal conductor fill and provide reasonable metal conductor resistance, then the metal conductor resistance improves, but plasma penetrates into the underlying metal layer during plasma densification causing nitrogen penetration and nitridization
Solution Approach 1:
The patent applies power of 300 W or less to the densification plasma, which is a parameter change that reduces the energy of plasma ions. This prevents plasma penetration into the underlying metal layer while still achieving effective barrier layer densification, thus avoiding nitrogen contamination and nitridization of the underlying metal
Solution Approach 2:
The patent introduces an intermediary parameter (power limit of 300 W) that mediates between the need for effective plasma densification and the need to prevent plasma penetration. This power threshold acts as a boundary condition that allows beneficial densification effects while blocking harmful penetration effects
2Length of moving object
If the thickness of the barrier layer is reduced, then the barrier layer allows better metal conductor fill, but the barrier layer becomes more permeable to plasma during densification
Solution Approach 1:
The patent changes the power parameter to 300 W or less during plasma densification, which prevents plasma penetration into the underlying metal even when the barrier layer is thin. This parameter change decouples the relationship between barrier layer thickness and plasma permeability, allowing thin barrier layers to maintain their integrity
3Manufacturing precision
If the power applied to densification plasma is increased to improve densification effectiveness, then the barrier layer density increases, but plasma penetration into the underlying metal increases causing nitridization
Solution Approach 1:
The patent identifies and applies a specific power threshold (300 W or less) that optimizes the densification process. At this power level, the plasma has sufficient energy to densify the barrier layer effectively but not enough energy to penetrate into the underlying metal and cause nitridization, thus resolving the contradiction between densification effectiveness and prevention of harmful effects
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
This process improves barrier layer properties, prevents pinch-off, and enhances the performance of semiconductor devices by maintaining the integrity of the underlying layers and adjusting the carbon to nitrogen ratio in the barrier layer.
Implementation Method 1
Plasma densification processes generally apply a power of 500 W or greater to the densification plasma, bombarding the barrier layer with plasma ions
Implementation Method 2
Plasma penetration into the underlying layers may force elements from the barrier layer, such as nitrogen or oxygen, into the underlying layer. For example, in titanium/titanium nitride layers, plasma nitridization of the underlying titanium can occur
Data Source
AI summary
An aspect of the present disclosure relates to a method of forming a barrier layer on a semiconductor device. The method includes placing a substrate into a reaction chamber and depositing a barrier layer over the substrate. The barrier layer includes a metal and a non-metal and the barrier layer exhibits an as-deposited thickness of 4 nm or less. The method further includes densifying the barrier layer by forming plasma from a gas proximate to said barrier layer and reducing the thickness and increasing the density of the barrier layer. In embodiments, during densification 300 Watts or less of power is applied to the plasma at a frequency of 350 kHz to 40 MHz.