PEALD Silicon Film Deposition for Faster High-Aspect-Ratio Gap Fill
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Solution Overview
Problem
Existing semiconductor fabrication processes face challenges in efficiently depositing silicon-containing films, particularly in high aspect ratio gaps and complex structures like 3D NAND, due to limitations in growth rates and cycle times in plasma-enhanced atomic layer deposition (PEALD) processes.
Innovation Solution
The method involves controlling flow rates and timing sequences in PEALD cycles by allowing silicon-containing precursor to flow during purge and plasma exposure phases, incorporating dual frequency RF plasma, and integrating a CVD-type component to enhance growth rates and fill gaps effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional PEALD processes are used to deposit silicon-containing films, then film quality and conformality are maintained, but deposition rates are slow and cycle times are long
Solution Approach 1:
The precursor flow is extended continuously through the purge phase and into the plasma phase, eliminating traditional flow interruptions. This continuous supply ensures that surface sites remain saturated with precursor throughout the cycle, enabling higher deposition rates without sacrificing conformality or film quality, thus resolving the contradiction between productivity and time loss
Solution Approach 2:
The precursor is introduced and allowed to adsorb onto the substrate surface before the plasma phase begins, ensuring complete surface coverage is achieved in advance. This preliminary saturation of surface sites with precursor enables the subsequent plasma reaction to proceed at maximum efficiency, increasing deposition rate while maintaining the self-limiting nature of ALD that ensures conformal coverage
2Productivity
If precursor flow is stopped during purge and plasma phases, then process control and film uniformity are maintained, but deposition efficiency decreases
Solution Approach 1:
The precursor flow continues uninterrupted through the purge and plasma phases, maintaining constant saturation of surface sites. This continuous action prevents any interruption in the deposition process, maximizing efficiency while the self-limiting surface reaction mechanism inherently maintains uniformity across the substrate surface
Solution Approach 2:
The process relies on the self-limiting nature of the surface reaction to automatically regulate deposition uniformity. The precursor continuously available in the chamber allows surface sites to self-regulate their reaction rates, ensuring uniform film growth without requiring precise flow interruption timing, thus improving efficiency while maintaining precision
3Manufacturing precision
If high aspect ratio gaps are filled using conventional PEALD, then conformal coverage is achieved, but the process requires excessive cycles and time
Solution Approach 1:
The continuous precursor flow ensures that all surface sites throughout high aspect ratio gaps remain saturated with precursor during each cycle. This eliminates diffusion limitations that typically slow down gap filling, allowing conformal coverage to be achieved at maximum deposition rate, thus reducing the number of cycles and total time required
Solution Approach 2:
The extended precursor exposure ensures that regions deep within high aspect ratio gaps receive adequate precursor supply, creating locally optimized deposition conditions throughout the entire gap volume. This local quality enhancement maintains conformal coverage while dramatically improving the deposition rate in difficult-to-reach areas
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 increases deposition rates, fills high aspect ratio gaps efficiently, and reduces cycle times, enabling better gap filling in structures such as 3D NAND and DRAM by forming conformal films with controlled CVD-type components.
Implementation Method 1
a dose operation including flowing a silicon-containing precursor into the processing station via the showerhead to allow the silicon-containing precursor to adsorb onto the substrate
Implementation Method 2
exposing the substrate to plasma species to react with the adsorbed silicon-containing precursor
Implementation Method 3
depositing silicon-containing film in the gap by a plasma-enhanced atomic layer deposition (PEALD) process
Implementation Method 4
the plasma in (c) is a dual frequency RF plasma generated using high frequency (HF) and low frequency (LF) RF power
Data Source
AI summary
Methods of depositing silicon-containing films by plasma-enhanced atomic layer deposition (PEALD) are described and can include one or more techniques to provide a chemical vapor deposition (CVD)-type component.