Nickel Silicide Etching via Fluorocarbon Plasma
Solution Overview
Problem
The existing methods for plasma etching of nickel silicide layers in semiconductor substrates face issues with non-volatile reactive by-products leading to metal re-deposition and defects such as electrical shorts and non-straight feature profiles due to the formation of problematic plasma-generated particulate by-products.
Innovation Solution
A method involving a single gas mixture with preselected constituents to form soluble or volatile products, which reduces or eliminates re-deposition and promotes the formation of nickel silicide edges with profiles greater than 80 degrees by using a plasma with controlled ion energy, thereby facilitating straight side edges and reducing defect generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional plasma etching is used on nickel silicide layers, then etching can be performed, but non-volatile reactive by-products are formed leading to metal re-deposition and defects
Solution Approach 1:
The patent changes the chemical parameters of the etching process by using a fluorocarbon-based plasma chemistry (CF4, C4F6, or C4F8) instead of conventional chemistries. This parameter change transforms the etching reactions to produce volatile fluorinated by-products that can be easily removed, eliminating the formation of non-volatile reactive by-products and subsequent metal re-deposition issues.
Solution Approach 2:
The patent exploits phase transitions by ensuring that the etching by-products are in the gas phase (volatile) rather than condensed phase (non-volatile). The fluorocarbon-based chemistry produces volatile fluorinated nickel and silicon compounds that remain in the gas phase and can be pumped away, preventing re-deposition on the substrate and sidewalls.
2Productivity
If conventional plasma etching is used on nickel silicide layers, then etching can be performed, but problematic plasma-generated particulate by-products are formed causing electrical shorts and patterning defects
Solution Approach 1:
The patent changes the chemical composition parameters of the plasma to use fluorocarbon-based gases (CF4, C4F6, or C4F8). This parameter change fundamentally alters the by-product chemistry from forming problematic particulate matter to forming volatile fluorinated compounds that are easily removed, thereby eliminating electrical shorts and patterning defects.
3Productivity
If conventional plasma etching is used on nickel silicide layers, then etching can be performed, but non-straight feature profiles are formed due to sidewall re-deposition
Solution Approach 1:
The patent changes the etching chemistry parameters to fluorocarbon-based plasma, which prevents metal re-deposition on sidewalls. This parameter change ensures that etched features maintain straight vertical profiles without the tapering or irregularities caused by re-deposited metal, thereby improving manufacturing precision of feature profiles.
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 approach allows for effective etching of nickel silicide layers with reduced metallic by-products and sidewall re-deposition, resulting in improved profile control and reduced defects, enabling the use of nickel silicide as a conductor material for interconnect applications with enhanced downstream processing capabilities.
Implementation Method 1
contacting a nickel silicide film disposed on a substrate in a process chamber with an etching gas sufficient to form one or more soluble or volatile products
Implementation Method 2
form one or more soluble or volatile products in order to reduce or eliminate re-deposition of products formed from the nickel silicide film
Data Source
AI summary
Methods and apparatus for processing a substrate and etching a nickel silicide layer are provided herein. In some embodiments, a method of etching a nickel silicide film in a semiconductor device include: contacting a nickel silicide film disposed on a substrate in a process chamber with an etching gas sufficient to form one or more soluble or volatile products in order to reduce or eliminate re-deposition of products formed from the nickel silicide film upon the nickel silicide film.