Flowable Polymer Masking for Selective Tungsten Gapfill
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Solution Overview
Problem
As semiconductor device geometries shrink and thermal budgets are reduced, conventional deposition processes struggle to achieve defect-free filling of small spaces, leading to challenges in selective tungsten deposition and removal, especially from field and sidewall surfaces.
Innovation Solution
A method involving the formation of a flowable polymer film within substrate features, allowing for selective removal of metal materials, such as tungsten, from the top surface without affecting material beneath the polymer film, followed by etching of the tungsten from the sidewalls and subsequent selective deposition of a second metal material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional deposition processes are used to fill small features, then the filling process can be performed, but defect-free filling cannot be achieved due to thermal budget constraints and geometry shrinkage
Solution Approach 1:
A polymer film is deposited beforehand within the feature to serve as a sacrificial layer that enables subsequent selective metal removal. This preliminary action prepares the structure for bottom-up fill by preventing unwanted metal deposition on field and sidewall surfaces, thereby enabling defect-free filling of small features despite thermal budget constraints
2Manufacturing precision
If selective tungsten deposition is performed, then tungsten can be deposited on the seed layer, but unwanted tungsten deposition occurs on field and sidewall surfaces
Solution Approach 1:
The polymer film acts as an intermediary sacrificial layer between the substrate and the metal deposition process. It selectively prevents tungsten deposition on field and sidewall surfaces while allowing deposition within the feature, thereby eliminating unwanted tungsten deposition without compromising the selective filling process
3Manufacturing precision
If minimum seed layer thickness is required for selective tungsten fill, then sufficient tungsten deposition can be achieved, but the process complexity increases due to additional seed layer formation steps
Solution Approach 1:
The polymer film is extracted as a separate sacrificial component that enables selective metal removal after deposition. This extraction approach allows the use of thinner seed layers while maintaining fill quality, as the polymer provides the necessary selectivity for metal removal without requiring thick seed layers for process control
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 method enables effective selective removal of unwanted tungsten deposition, facilitating bottom-up fill processes and improving the filling of small features in semiconductor manufacturing.
Implementation Method 1
A flowable polymer film is formed within the at least one feature
Implementation Method 2
At least a portion of the tungsten material is selectively removed from the top surface without substantially affecting the tungsten material beneath the polymer film
Implementation Method 3
The polymer film is removed to expose the tungsten material beneath the polymer film. The tungsten material is etched from the at least one sidewall
Data Source
AI summary
Embodiments of the disclosure relate to methods for selectively removing metal material from the top surface and sidewalls of a feature. The metal material which is covered by a flowable polymer material remains unaffected. In some embodiments, the metal material is formed by physical vapor deposition resulting in a relatively thin sidewall thickness. Any metal material remaining on the sidewall after removal of the metal material from the top surface may be etched by an additional etch process. The resulting metal layer at the bottom of the feature facilitates selective metal gapfill of the feature.