Seamless Gapfill in High Aspect Ratio Trenches
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Solution Overview
Problem
Current methods for filling narrow trenches with high aspect ratios in microelectronics device fabrication often result in seam formation and voiding due to inadequate film penetration and deposition rate imbalances, leading to poor film quality and structural failures.
Innovation Solution
A cyclic deposition-treatment-etch process is employed, using gases like Ar, He, or H2 to modify the silicon film's structure and composition, followed by etching with H2, HCl, or Cl2 to ensure conformal coverage and seam-free filling of high aspect ratio trenches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional PECVD is used to deposit amorphous silicon in narrow trenches, then deposition speed is improved, but the plasma cannot penetrate into deep trenches resulting in mushroom-shaped films and void formation
Solution Approach 1:
The patent employs a cyclic deposition-etch process where thin silicon layers are deposited periodically followed by selective removal at trench tops. This periodic action allows controlled material accumulation that penetrates deep trenches uniformly without forming mushrooms or voids, resolving the contradiction between deposition speed and film uniformity in high aspect ratio structures.
Solution Approach 2:
The patent changes deposition parameters by using low-temperature CVD conditions and controlling precursor flow to achieve linear deposition profiles that maintain uniform thickness throughout high aspect ratio trenches. This parameter optimization enables faster deposition while preventing plasma penetration issues that cause non-uniform films.
2Manufacturing precision
If thermal CVD/furnace processes are used to grow amorphous silicon, then seam formation is avoided, but deposition rate is higher on top of trenches than at the bottom due to inadequate precursor supply
Solution Approach 1:
The cyclic deposition-etch process breaks down the deposition into multiple thin layers with intermediate treatments. This periodic action ensures uniform precursor distribution and reaction throughout the trench depth, achieving both seam-free growth and uniform deposition rates by preventing the accumulation of byproducts that cause rate variations.
Solution Approach 2:
The patent applies preliminary surface treatments and optimizes precursor delivery before deposition to ensure uniform reactant distribution. This preliminary action prevents inadequate precursor supply at trench bottoms, enabling uniform deposition rates while maintaining seam-free film quality.
3Manufacturing precision
If flowable CVD is used to fill trenches, then conformal coverage is achieved, but the as-deposited film is of very poor quality requiring steam anneals and UV-cures
Solution Approach 1:
The cyclic deposition-etch process with intermediate plasma treatments produces inherently high-quality films during deposition. This periodic action with in-situ treatments eliminates the need for post-deposition steam anneals and UV-cures, achieving both conformal coverage and high film quality without additional processing steps.
Solution Approach 2:
The patent replaces post-deposition thermal and chemical treatment steps with controlled plasma processing during the deposition cycle. This substitution of mechanics achieves film quality improvement through physical-chemical plasma interactions rather than requiring separate steam annealing and UV-curing processes.
4Reliability
If furnace poly-silicon or amorphous silicon dummy gate is used in metal replacement gate processes, then etch selectivity is improved, but a seam forms in the middle of the dummy gate causing structure failure
Solution Approach 1:
The cyclic deposition-etch process creates uniform, seam-free silicon films with consistent microstructure. This periodic action ensures homogeneous material properties throughout the dummy gate, maintaining both etch selectivity and structural integrity by eliminating seams that would cause failure during subsequent processing.
Solution Approach 2:
The patent optimizes deposition parameters to produce uniform films with controlled microstructure and stress distribution. These parameter changes ensure the silicon dummy gate maintains structural integrity while preserving etch selectivity, preventing seam formation that leads to device failure.
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 process achieves high-quality, seam-free film growth within narrow trenches, enhancing the reliability of microelectronics devices by ensuring uniform film thickness and preventing void formation.
Implementation Method 1
The silicon film is exposed to a treatment to modify a structure, composition or morphology of the silicon film. The treatment comprises exposure to one or more of Ar, He or H2.
Implementation Method 2
The film is etched from the substrate surface using one or more of H2, HCl or Cl2 to remove substantially all of the film from the substrate surface
Implementation Method 3
The deposition, treatment and etching are repeated to fill the feature.
Data Source
AI summary
Methods for seam-less gapfill comprising depositing a film in a feature, treating the film to change some film property and selectively etching the film from the top surface are described. The deposition, treatment and etching are repeated to form a seam-less gapfill in the feature.