Protective Liner for Contact Opening Profile Integrity
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Solution Overview
Problem
Existing methods for forming self-aligned silicide (salicide) in semiconductor devices face challenges such as damage to the opening profile and uncontrolled salicide formation due to directional physical bombardment, and enlargement of contact openings due to in-situ chemical pre-clean, which can lead to critical dimension failures and isolation issues.
Innovation Solution
The use of a protective liner along the sidewalls and bottom of contact openings to prevent damage during pre-cleaning, followed by a chemical etch process that protects the sidewalls and maintains critical dimensions, allowing for controlled salicide formation and reliable contact plug isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If directional physical bombardment is used for pre-clean, then cleaning effectiveness is improved, but opening profile damage occurs
Solution Approach 1:
A protective liner is introduced as an intermediary layer between the opening wall and the cleaning plasma. The liner material (such as silicon nitride or silicon oxide) is selectively removed at the opening bottom while remaining intact during sidewall cleaning, thus protecting the opening profile from damage while allowing effective cleaning of the substrate surface.
Solution Approach 2:
The protective liner is segmented in function: it protects the sidewalls during cleaning but is selectively removed at the bottom to allow substrate access. This segmentation allows the cleaning process to be effective without damaging the overall opening structure.
2Manufacturing precision
If in-situ chemical pre-clean is used, then opening profile damage is reduced, but opening enlargement occurs
Solution Approach 1:
The protective liner acts as a barrier that prevents the chemical etchant from attacking the opening sidewalls, thus preventing opening enlargement. The liner is selectively removed at the bottom through controlled etching conditions, allowing substrate access while maintaining sidewall integrity.
3Reliability
If directional physical bombardment is used, then cleaning is achieved, but uncontrolled salicide formation occurs
Solution Approach 1:
The protective liner prevents direct plasma bombardment of the substrate at the opening bottom, thereby preventing uncontrolled salicide formation. The liner is selectively removed to expose the substrate only where needed, allowing controlled salicide formation in the desired locations.
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 prevents damage to the contact openings, maintains precise dimensions, and ensures reliable salicide formation, enhancing the electrical isolation and performance of semiconductor devices.
Implementation Method 1
The use of a protective liner along the sidewalls and bottom of contact openings to prevent damage during pre-cleaning
Implementation Method 2
followed by a chemical etch process that protects the sidewalls and maintains critical dimensions
Implementation Method 3
The salicide may be formed by forming a metal layer in the opening and against the substrate and then annealing the metal layer and substrate in order to form the salicide
Data Source
AI summary
A system and method for forming and using a liner is provided. An embodiment comprises forming an opening in an inter-layer dielectric over a substrate and forming the liner along the sidewalls of the opening. A portion of the liner is removed from a bottom of the opening, and a cleaning process may be performed through the liner. By using the liner, damage to the sidewalls of the opening from the cleaning process may be reduced or eliminated. Additionally, the liner may be used to help implantation of ions within the substrate.