Selective Catalyst Deposition for Void-Free High Aspect Ratio Gap Fill
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Solution Overview
Problem
Current methods for forming conformal dielectric films in high aspect ratio structures, such as CVD and ALD, face challenges with void formation and slow deposition rates, particularly in filling gaps with re-entrant features, leading to incomplete fills and the need for additional processing steps like CMP to remove excess film on the field.
Innovation Solution
A method involving a two-step process where a catalyst or catalyst precursor is selectively applied to a substrate surface, followed by exposure to a silicon-containing precursor gas, allowing for controlled conformal deposition of silicon oxide-based films, either to fill gaps completely or partially, using PDL or ALD processes, with parameters like residence and soak time controlling film coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional CVD techniques are used to deposit silicon dioxide films, then deposition rate is high, but void-free gap-fill cannot be achieved in high aspect ratio features
Solution Approach 1:
The deposition process is divided into multiple sequential ALD cycles, each depositing a thin conformal layer. This segmentation allows precise control over film thickness and ensures complete gap-fill in high aspect ratio features by building up the dielectric layer incrementally rather than attempting single-step deposition.
Solution Approach 2:
The patent employs periodic alternation between precursor introduction and purge steps in the ALD process. Reactant gases are introduced alternately over the substrate surface in repeated cycles, with each cycle consisting of precursor exposure followed by purging, enabling controlled conformal deposition while maintaining high aspect ratio gap-fill capability.
2Manufacturing precision
If ALD methods are used to deposit conformal dielectric films in high aspect ratio features, then uniform film thickness is achieved, but deposition rate is very low requiring numerous cycles
Solution Approach 1:
The patent modifies ALD process parameters including precursor selection, exposure times, and temperature conditions to optimize deposition rate while maintaining conformality. By adjusting these parameters, the process achieves faster deposition speeds without sacrificing the uniform film thickness required for high aspect ratio gap-fill applications.
Solution Approach 2:
The patent introduces a catalyst or catalyst precursor as an intermediary substance that enhances the deposition reaction. This catalyst facilitates faster reaction kinetics between precursors, thereby increasing deposition rate while the self-limiting nature of ALD cycles maintains film conformality in high aspect ratio structures.
3Productivity
If PDL processing is used to achieve rapid film growth, then deposition rate increases similar to CVD, but void formation occurs in high aspect ratio trenches
Solution Approach 1:
The patent applies catalyst or catalyst precursor selectively to specific regions rather than uniformly across the entire substrate. This partial action allows control over where deposition occurs, enabling rapid growth in desired areas while preventing excessive deposition that would cause void formation in high aspect ratio trenches. The catalyst is applied to enhance growth rate locally without compromising gap-fill 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 enables seamless and void-free gap fills in high aspect ratio structures, allowing for precise control over film coverage, reducing the need for extensive processing and improving deposition efficiency by preventing film formation in specific areas, such as the bottom of trenches, to create sacrificial masks or achieve bottom-up gap fills.
Implementation Method 1
the catalyst-activated surface decomposes the silicon-oxide precursor leading ultimately to growth of a conformal silica film on the substrate
Implementation Method 2
ALD methods involve self-limiting adsorption of reactant gases
Data Source
AI summary
Methods for forming thin dielectric films by selectively depositing a conformal film of dielectric material on a high aspect ratio structure have uses in semiconductor processing and other applications. A method for forming a dielectric film involves providing in a deposition reaction chamber a substrate having a gap on the surface. The gap has a top opening and a surface area comprising a bottom and sidewalls running from the top to the bottom. A conformal silicon oxide-based dielectric film is selectively deposited in the gap by first preferentially applying a film formation catalyst or a catalyst precursor on a portion representing less than all of the gap surface area. The substrate surface is then exposed to a silicon-containing precursor gas such that a silicon oxide-based dielectric film layer is preferentially formed on the portion of the gap surface area. The preferential application of the catalyst or catalyst precursor may occur either at the top of the gap, for example to form a sacrificial mask, or at the bottom of the gap to create a seamless and void-free gap fill.