Tungsten Plug Cleaning via Organic Amine Inhibitor
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Solution Overview
Problem
In the manufacturing of integrated circuits, the use of Chemical Mechanical Polish (CMP) for tungsten contact plugs results in corrosion and recessing during cleaning, which complicates the filling of subsequent conductive features due to deep and narrow recesses, especially in newer generation circuits with narrower plugs, leading to potential open circuits.
Innovation Solution
A cleaning solution with an organic amine inhibitor is used to prevent corrosion of tungsten plugs by maintaining a pH value between 7.0 and 8.0, which attaches to the plug surface and prevents electron flow and ion dissolution, reducing recess depth and ensuring the plug's integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cleaning solution is used to clean the wafer after CMP, then cleaning effectiveness is improved, but corrosion and recessing of tungsten plugs occurs
Solution Approach 1:
An organic amine inhibitor is introduced as an intermediary substance in the cleaning solution that mediates between the cleaning agents and the tungsten plug surface. The inhibitor adsorbs onto the tungsten surface, forming a protective layer that prevents direct contact between corrosive cleaning components and the tungsten, thereby eliminating corrosion and recessing while maintaining cleaning effectiveness.
Solution Approach 2:
The pH value of the cleaning solution is controlled within a specific range (7.0-8.0) to optimize the balance between cleaning effectiveness and prevention of tungsten corrosion. By adjusting this critical parameter, the cleaning solution achieves sufficient cleaning power without causing harmful corrosion and recessing of the tungsten plugs.
2Reliability
If conventional cleaning solutions are used, then cleaning is achieved, but deep and narrow recesses are formed complicating subsequent conductive feature filling
Solution Approach 1:
The organic amine inhibitor serves as a protective intermediary that prevents the formation of deep and narrow recesses on the tungsten plug surface during cleaning. By adsorbing onto the surface and providing steric and electronic protection, it prevents excessive material removal that would create difficult-to-fill topographies, thereby maintaining manufacturing precision while achieving cleaning completion.
3Device complexity
If pH value is not controlled, then cleaning solution is simpler, but corrosion protection is insufficient
Solution Approach 1:
The pH value of the cleaning solution is controlled within a specific range (7.0-8.0) to optimize the balance between cleaning effectiveness and prevention of tungsten corrosion. By adjusting this critical parameter, the cleaning solution achieves sufficient cleaning power without causing harmful corrosion and recessing of the tungsten plugs.
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 solution effectively minimizes corrosion and recessing, allowing for easier filling of conductive features without generating open circuits, even in narrow tungsten plugs, by using a weak base solution with an organic amine inhibitor, ensuring the pH value is within the effective range.
Implementation Method 1
a cleaning solution with an organic amine inhibitor is used to prevent corrosion of tungsten plugs by maintaining a pH value between 7.0 and 8.0, which attaches to the plug surface and prevents electron flow and ion dissolution
Data Source
AI summary
A method includes forming a first dielectric layer over a wafer, etching the first dielectric layer to form an opening, filling a tungsten-containing material into the opening, and performing a Chemical Mechanical Polish (CMP) on the wafer. After the CMP, a cleaning is performed on the wafer using a weak base solution.