Multi-Tier Tungsten Gapfill With Growth Inhibition at Narrow Openings
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Solution Overview
Problem
Conventional tungsten deposition processes in semiconductor manufacturing often result in voids and seams within high aspect ratio features, particularly in multi-tier structures, leading to incomplete filling and increased susceptibility to corrosion during chemical mechanical polishing.
Innovation Solution
A method involving cyclic exposure of tungsten-containing gases and reducing agents, combined with nitrogen trifluoride or nitrogen-containing plasma, to form a nucleation layer and inhibit growth at narrow portions, ensuring complete filling and seam-free tungsten features without transferring the substrate between processing chambers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional tungsten deposition is used to fill high aspect ratio features, then the deposition process is simple and fast, but voids and seams form within the features leading to incomplete filling
Solution Approach 1:
The deposition process is segmented into multiple cycles alternating between tungsten-containing gas exposure and reducing agent exposure. This segmentation allows controlled nucleation layer formation followed by fill layer deposition, preventing void and seam formation while maintaining processability.
Solution Approach 2:
A nucleation layer is formed preliminarily within the high aspect ratio features before the main fill layer deposition. This preliminary action creates a foundation that enables complete filling without voids and seams, resolving the contradiction between filling completeness and process complexity.
2Productivity
If higher precursor gas concentration is used to deposit tungsten fill layer quicker, then deposition speed increases, but void formation is exacerbated in varying channel sidewall widths
Solution Approach 1:
The deposition process uses periodic action by alternating between tungsten-containing gas exposure and reducing agent exposure in cycles. This periodic approach allows controlled deposition that maintains filling uniformity across varying channel sidewall widths while achieving acceptable deposition speeds through repeated cycles.
Solution Approach 2:
The process creates local quality differences by forming a nucleation layer with specific properties within the features before depositing the fill layer. This local differentiation in deposition characteristics ensures uniform filling across regions with varying sidewall widths, preventing void formation while maintaining overall productivity.
3Manufacturing precision
If cyclic exposure to tungsten-containing gas and reducing agent is used to form nucleation layer, then void and seam formation is prevented, but processing time increases
Solution Approach 1:
The process uses partial action by forming only a thin nucleation layer through cyclic exposure rather than complete filling. This partial nucleation layer formation prevents void and seam issues, and the subsequent fill layer deposition completes the process efficiently, balancing filling quality with processing time.
4Manufacturing precision
If nitrogen trifluoride containing gas is used to inhibit growth at narrow portions, then complete filling is achieved, but material loss during polishing increases due to seams and voids
Solution Approach 1:
The nucleation layer is formed preliminarily with controlled growth inhibition at narrow portions using nitrogen trifluoride containing gas. This preliminary structured layer prevents subsequent void and seam formation during fill layer deposition, thereby eliminating the root cause of tungsten material loss during polishing while maintaining filling completeness.
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 effectively prevents void formation and seam creation, enabling complete filling of high aspect ratio features and reducing material loss during polishing, thereby improving the reliability and efficiency of tungsten gapfill processes.
Implementation Method 1
exposing at least one opening formed in a multi-tier portion of the substrate to a tungsten-containing gas at a precursor gas flow rate and exposing the at least one opening of the substrate to a reducing agent comprising boron at a reducing agent flow rate. The tungsten-containing gas and the reducing agent are alternated cyclically to form a nucleation layer within the at least one opening of the substrate
Implementation Method 2
exposing the at least one opening of the substrate to a nitrogen trifluoride containing gas to inhibit growth of the nucleation layer at narrow portions within the at least one opening
Data Source
AI summary
A method of forming a structure on a substrate includes forming a tungsten nucleation layer within at least one opening within a multi-tier portion of a substrate. The method includes exposing the nucleation layer a nitrogen trifluoride-containing gas to inhibit growth of the nucleation layer at narrow portions within the at least one opening. The method includes exposing the at least one opening to the tungsten-containing precursor gas to form a fill layer over the nucleation layer within the at least one opening. The method includes exposing the at least one opening of the substrate to the nitrogen trifluoride-containing gas or a nitrogen-containing plasma to inhibit growth of portions of the fill layer along the at least one opening.