Bottom-Up Gap-Fill via Surface Poisoning in High Aspect Ratio Trenches
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Solution Overview
Problem
Current methods for filling narrow trenches in microelectronics device fabrication with high aspect ratios struggle to achieve high-quality, void-free films, especially as structure dimensions decrease and aspect ratios increase, leading to varying composition throughout the trench.
Innovation Solution
The method involves exposing a substrate with features to an organic-based poisoning agent to inhibit film growth at the top relative to the bottom, followed by sequential exposure to a precursor and reactant in a processing chamber with gas curtains to facilitate bottom-up film deposition using atomic layer deposition (ALD) processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If flowable CVD is used to fill narrow trenches, then the trenches can be filled, but the as-deposited film is of very poor quality and requires additional processing steps
Solution Approach 1:
The substrate surface is pre-treated with an organic-based poisoning agent before film deposition to modify surface properties. This preliminary action ensures that the as-deposited film achieves high quality directly, eliminating the need for subsequent steam anneals and UV-cures that were required with conventional flowable CVD methods.
2Manufacturing precision
If conventional gap-fill methods are used, then films can be deposited, but voids form and composition varies throughout the trench
Solution Approach 1:
The organic-based poisoning agent creates non-uniform surface modification across the trench structure, with different poisoning levels at the top versus bottom surfaces. This local quality differentiation enables bottom-up film growth where the film deposits preferentially at the bottom first, ensuring uniform composition and eliminating voids throughout the trench fill.
Solution Approach 2:
Instead of the conventional top-down or simultaneous deposition approach, the poisoning treatment inverts the growth sequence to bottom-up deposition. The organic-based poisoning agent preferentially suppresses deposition at the top surface while allowing it at the bottom, reversing the typical growth pattern to achieve void-free filling.
3Productivity
If aspect ratios increase with decreasing dimensions, then device density improves, but film quality becomes difficult to maintain
Solution Approach 1:
The process changes the chemical parameters of the substrate surface by introducing an organic-based poisoning agent. This parameter change modifies the surface reactivity and deposition kinetics, enabling high-quality film deposition even in high aspect ratio trenches where conventional methods fail to maintain film quality.
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 allows for high-quality film deposition with no voiding and low leakage, effectively filling trenches with aspect ratios greater than 10:1, maintaining film quality throughout, and achieving high throughput and repeatability.
Implementation Method 1
exposing a substrate surface having at least one feature thereon to an organic-based poisoning agent to preferentially poison a top of the feature relative to a bottom of the feature
Implementation Method 2
The substrate surface is sequentially exposed to a precursor and a reactant to deposit a layer in the gap. The precursor and reactant are repeatedly exposed to fill the gap of the feature in a bottom-up manner
Data Source
AI summary
Methods for depositing film comprising exposing a substrate surface to an organic-based poisoning agent to preferentially inhibit film growth at the top of a feature relative to the bottom of the feature and depositing a film. The substrate can be exposed to the poisoning agent any number of times to promote bottom-up growth of the film in the feature.