Seamless Gap Fill in High Aspect Ratio Trenches
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Solution Overview
Problem
The semiconductor industry faces challenges in filling narrow trenches with high aspect ratios greater than 10:1 in microelectronic devices without voiding, as existing methods like CVD and ALD often result in films with varying composition and seam formation in 3-dimensional structures, making it difficult to achieve seamless gap fill.
Innovation Solution
A processing method involving forming a metal film on a substrate with high aspect ratio features, treating it with plasma, and annealing to create a seamless and high-quality film fill, specifically using a film stack of alternating oxide and nitride layers and depositing metal films like titanium nitride in a cluster tool environment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If CVD or ALD techniques are used to deposit film into high aspect ratio trenches, then film deposition is achieved, but the film quality varies throughout the trench and seams form in 3-dimensional structures
Solution Approach 1:
A mandrel structure is formed within the trench before metal film deposition. This mandrel serves as a preliminary structural element that guides the metal film deposition process, ensuring uniform coverage and preventing seam formation during subsequent filling operations.
Solution Approach 2:
The mandrel acts as an intermediary structure between the trench walls and the metal film. It provides a controlled interface that enables uniform metal film deposition across the high aspect ratio trench, eliminating the seam formation problem that occurs with direct deposition methods.
2Manufacturing precision
If multiple deposition-etch-deposition cycles are used to fill trenches, then gap fill is improved, but process complexity and cost increase
Solution Approach 1:
The trench filling process is segmented into distinct phases: mandrel formation, metal film deposition over the mandrel, and mandrel removal. This segmentation allows each step to be optimized independently, achieving complete gap fill in a single deposition cycle rather than requiring multiple repetitive cycles.
Solution Approach 2:
The mandrel is formed in advance as a preliminary structure that enables complete trench filling during a single metal deposition step. This preliminary action eliminates the need for multiple deposition-etch-deposition cycles, significantly reducing process complexity.
3Manufacturing precision
If aggressive radical treatment steps are applied to improve film quality, then film properties are enhanced, but integration concerns arise for some applications
Solution Approach 1:
The mandrel structure enables the metal film to self-organize and deposit uniformly during a single CVD or ALD cycle without requiring aggressive radical treatment steps. The mandrel provides structural guidance that allows the deposition process to proceed under milder, more universally compatible conditions.
Solution Approach 2:
The deposition parameters can be optimized to milder conditions when using the mandrel approach, as the mandrel structure ensures uniform film formation without requiring aggressive treatment. This allows the process to be integrated with a broader range of existing semiconductor fabrication processes.
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 the deposition of seamless, high-quality metal films in high aspect ratio trenches, reducing voids and ensuring uniform coverage, which is crucial for advanced microelectronic devices such as 3D NAND and DRAM structures.
Implementation Method 1
treating the metal film with a plasma
Implementation Method 2
annealing the metal film
Data Source
AI summary
Methods for filling a substrate feature with a seamless gap fill are described. Methods comprise forming a metal film a substrate surface, the sidewalls and the bottom surface of a feature, the metal film having a void located within the width of the feature; treating the metal film with a plasma; and annealing the metal film to remove the void.