Cluster Tool Barrier Overhang Removal via Amorphous Carbon Film
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Solution Overview
Problem
In semiconductor fabrication, the formation of barrier material overhangs in contact holes leads to incomplete fill-in of conducting metal, resulting in imperfections such as voids and seams, which degrade integrated circuit performance and increase manufacturing costs.
Innovation Solution
A cluster tool system comprising a chamber for depositing barrier material, followed by an amorphous carbon film (ACF) coating and etchback to expose and remove the barrier overhang, facilitating complete fill-in of contact holes with conducting metal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If barrier material is deposited to line the contact hole, then isolation between conducting metal and surrounding material is improved, but barrier material overhang forms that occludes the contact hole opening and impedes metal fill-in
Solution Approach 1:
The patent applies preliminary action by depositing amorphous carbon film (ACF) over the barrier material overhang before metal fill-in. The ACF serves as a sacrificial layer that is subsequently removed via etchback, clearing the contact hole opening in advance to enable complete metal fill-in while maintaining the barrier material's isolation function.
Solution Approach 2:
The patent uses amorphous carbon film (ACF) as an intermediary material between the barrier material and the conducting metal. The ACF is deposited, patterned, and then removed via etchback, acting as a temporary mediator that facilitates the removal of barrier material overhang and enables complete metal fill-in without compromising the barrier's isolation function.
2Reliability
If barrier material overhang is present, then isolation function is maintained, but metal fill-in produces imperfections such as voids and seams
Solution Approach 1:
The patent performs preliminary removal of barrier material overhang by depositing ACF and subsequently etching it back before metal fill-in. This preliminary action eliminates the overhang that would otherwise cause voids and seams, ensuring high-quality metal fill-in while preserving the barrier material's isolation function on the contact hole walls.
Solution Approach 2:
The patent converts the harmful effect of barrier material overhang into a beneficial process feature. The overhang is intentionally allowed to form, then selectively removed using ACF as a mask and etchback process. This transforms the originally harmful overhang into a controlled intermediate state that facilitates precise metal fill-in without defects.
3Ease of manufacture
If conventional deposition process is used, then barrier material is deposited, but process variations cause overhang profile that occludes contact hole opening
Solution Approach 1:
The patent introduces amorphous carbon film (ACF) as an intermediary layer that compensates for deposition process variations. The ACF is deposited conformally over the barrier material, and its subsequent etchback removes the barrier overhang regardless of the original deposition variations, ensuring consistent contact hole opening clearance.
Solution Approach 2:
The patent changes the physical and chemical parameters of the deposited material by using amorphous carbon film instead of conventional crystalline materials. The ACF's unique properties (amorphous structure, specific etch selectivity) enable controlled removal of barrier overhang through etchback, compensating for variations in the barrier material deposition process.
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 ensures reliable and efficient metal fill-in of contact holes, reducing defects and increasing yield by eliminating barrier overhangs, thereby enhancing the reliability and performance of integrated circuit fabrication processes.
Implementation Method 1
The first chamber may comprise a radio-frequency physical vapor deposition (RF PVD) chamber
Implementation Method 2
the first chamber comprises a chemical vapor deposition (CVD) chamber
Implementation Method 3
a second chamber for fill-in of (e.g., via deposition) an amorphous carbon film (ACF)
Data Source
AI summary
A cluster tool is disclosed that can increase throughput of a wafer fabrication process by facilitating removal of barrier overhang in contact holes of contact film stacks. Individual chambers of the cluster tool provide for deposition of barrier material onto a semiconductor structure, depositing over with an amorphous carbon film (ACF), etching back the ACF, and etching a corner region of the contact hole. Removal of the barrier overhang improves the quality of metal fill-in of the contact hole. An expectedly ensuing feature entails a technique in which filling-in of the contact hole with a metal such as tungsten can be achieved with attenuated or eliminated adverse consequence.