ALD Additive for Gap Fill Profile Tuning
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Solution Overview
Problem
Atomic layer deposition (ALD) in high aspect ratio features faces challenges in achieving conformal coverage and gap-fill due to inadequate diffusion of reactant gases, leading to issues like void formation and seam creation, which negatively impact throughput and film quality.
Innovation Solution
A method involving simultaneous exposure of a substrate to a first reactant and an additive during ALD, where the additive competes for adsorption sites and is desorbed during a second dosing step, allowing controlled step coverage and increased deposition with depth, thereby preventing void formation and seam creation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ALD is used to achieve conformal coverage in high aspect ratio features, then film uniformity is improved, but deposition time increases significantly
Solution Approach 1:
The patent applies local quality by introducing an inhibitor that selectively adsorbs at different locations within the gap feature. The inhibitor concentration is controlled to provide stronger inhibition at the top of the feature and weaker inhibition at the bottom, enabling faster deposition rates at deeper locations while maintaining conformal coverage throughout the high aspect ratio feature.
2Reliability
If additional inhibitor steps are added to every ALD cycle to prevent pinch-off, then void formation is prevented, but throughput decreases
Solution Approach 1:
The patent merges the inhibitor function with the first reactant by combining them into a single dosing step. The inhibitor is delivered simultaneously with the first reactant during the same exposure step, eliminating the need for separate inhibitor dosing steps while still achieving the desired deposition profile and preventing void formation.
Solution Approach 2:
The first reactant serves multiple functions: it acts as both the deposition precursor and the carrier for the inhibitor. This multi-functionality reduces process complexity and maintains throughput by avoiding additional dedicated inhibitor dosing steps.
3Manufacturing precision
If plasma is used to deliver the inhibitor, then deposition control is improved, but damage to underlying layers occurs
Solution Approach 1:
The patent replaces the plasma-based inhibitor delivery mechanism with a thermal field-based approach. The inhibitor is delivered through controlled thermal desorption from a source, eliminating the need for plasma while maintaining precise deposition control through temperature management.
Solution Approach 2:
The process is conducted in an inert atmospheric environment that avoids plasma formation, preventing damage to underlying sensitive layers while still enabling controlled inhibitor delivery through thermal mechanisms.
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 conformal deposition with increased deposition rates along sidewalls and bottom-up filling of gap features, reducing the risk of voids and seams, while maintaining throughput by minimizing additional process steps and avoiding plasma damage.
Implementation Method 1
the first reactant and the additive being configured to adsorb on exposed surfaces of the substrate
Implementation Method 2
the second reactant configured to react with the adsorbed first reactant to form a thin film product
Implementation Method 3
form a thin film product
Implementation Method 4
the second reactant configured to react with the adsorbed additive to remove the adsorbed additive from the substrate surface
Data Source
AI summary
A method for performing atomic layer deposition (ALD) on a substrate is provided, including: exposing the substrate to a first reactant and an additive simultaneously, the first reactant and the additive being configured to adsorb on exposed surfaces of the substrate, a partial pressure of the additive being configured so that adsorption of the additive in a gap feature of the substrate decreases as depth increases in the gap feature; after exposing the substrate to the first reactant and the additive, exposing the substrate to a second reactant, the second reactant configured to react with the adsorbed first reactant to form a thin film product, the second reactant configured to react with the adsorbed additive to remove the adsorbed additive from the substrate surface.