Wrap-around Contact Plug Silicide Loss Prevention
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Solution Overview
Problem
Conventional silicide formation processes involve depositing a metal layer, followed by an anneal to form silicide, which can lead to oxidation and loss of metal silicide due to the need for wet etching to remove unreacted metal, causing inefficiencies in the manufacturing of integrated circuits.
Innovation Solution
The process involves in-situ selective deposition and etching in a vacuum environment to form a metal silicide layer on source/drain regions without oxidation, followed by selective nitridation to form a metal silicon nitride layer that wraps around the silicide, eliminating the need for oxide removal and minimizing metal silicide loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If a wet etch is performed to remove unreacted metal layer after anneal, then the unreacted metal is removed, but oxidation occurs and metal silicide is lost
Solution Approach 1:
The patent performs the etch process in a nitrogen atmosphere instead of using wet etching in ambient air. This inert environment prevents oxidation of the metal silicide during the etching process, thereby eliminating the loss of metal silicide that occurs with conventional wet etching methods while maintaining the ability to remove unreacted metal layer effectively
2Reliability
If conventional wet etching is used to remove unreacted metal, then the process is simple, but oxidation and metal silicide loss occur
Solution Approach 1:
The patent changes the fundamental parameter of the etching environment from ambient air to nitrogen atmosphere. This parameter change enables the etching process to remove unreacted metal without causing oxidation, thereby improving the reliability and integrity of the silicide formation while the additional complexity is minimal as it primarily involves atmosphere control
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 method prevents oxidation and reduces the loss of metal silicide, improving the efficiency and integrity of the silicide formation process, allowing for more reliable contact plug formation in integrated circuit manufacturing.
Implementation Method 1
The source/drain contact plugs are typically connected to source/drain silicide regions, which are formed by depositing a metal layer, and then performing an anneal to react the metal layer with the silicon of the source/drain regions
Implementation Method 2
performing an anneal to react the metal layer with the silicon of the source/drain regions
Implementation Method 3
in-situ selective deposition and etching in a vacuum environment to form a metal silicide layer on source/drain regions without oxidation
Implementation Method 4
followed by selective nitridation to form a metal silicon nitride layer that wraps around the silicide
Data Source
AI summary
A method includes forming a source/drain region, and in a vacuum chamber or a vacuum cluster system, preforming a selective deposition to form a metal silicide layer on the source/drain region, and a metal layer on dielectric regions adjacent to the source/drain region. The method further includes selectively etching the metal layer in the vacuum chamber, and selectively forming a metal nitride layer on the metal silicide layer. The selectively forming the metal nitride layer is performed in the vacuum chamber or a vacuum cluster system without vacuum break.