Steam-Initiated Radical Oxidation for Uniform HAR Oxide Coatings
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Solution Overview
Problem
Current semiconductor fabrication methods face challenges in conformally oxidizing high aspect ratio structures, such as 3D NAND flash memory structures, due to issues with material buildup and reduced processing efficiency, especially in achieving uniform oxidation across steep features.
Innovation Solution
A substrate oxidation assembly that includes a plasma source and a steam source, coupled with a substrate heater, is used to initiate conformal radical oxidation of high aspect ratio structures, forming a uniform Si2N2O layer which then reacts to form a conformal SiO2 layer, optimizing oxidation conditions by controlling temperature and reactant distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If slower deposition rate is used to achieve conformal coating on HAR structures, then coating uniformity is improved, but processing time increases and production efficiency decreases
Solution Approach 1:
The patent changes the chemical parameters of the oxidation process by introducing steam as a reactant and using plasma activation. This enables conformal oxidation of HAR structures at practical deposition rates by altering the reaction mechanism from thermal diffusion-limited to plasma-enhanced reaction-limited, achieving both uniformity and efficiency
Solution Approach 2:
The patent replaces the conventional thermal oxidation mechanism with plasma-enhanced oxidation. The plasma provides activated oxygen species that enable conformal deposition at higher rates by substituting the slow thermal diffusion process with a more reactive plasma-driven chemical process
2Ease of manufacture
If conventional thermal oxidation is used on HAR structures, then processing simplicity is maintained, but oxidation uniformity deteriorates due to material buildup at structure tops
Solution Approach 1:
The patent introduces steam as an intermediary reactant that facilitates uniform oxidation. The steam provides a controlled source of oxygen that penetrates HAR structures uniformly, preventing the material buildup problem associated with conventional thermal oxidation while maintaining process simplicity
Solution Approach 2:
The patent employs a two-stage periodic process: first plasma activation to prepare the surface and initiate oxidation, then steam exposure to complete the conformal oxidation. This periodic action sequence achieves uniform oxidation on HAR structures while keeping the overall process simple and integrated
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 ensures a conformal oxide layer with a thickness of at least 95% uniformity across the structure, improving processing efficiency and preventing material buildup, even at high aspect ratios, while maintaining structural integrity.
Implementation Method 1
heating the substrate
Implementation Method 2
exposing the substrate to steam; conformally oxidizing the substrate
Implementation Method 3
steam source fluidly coupled to the processing volume; exposing the substrate to steam
Implementation Method 4
plasma source coupled to the processing volume; conformal radical oxidation
Data Source
AI summary
A substrate oxidation assembly includes: a chamber body defining a processing volume; a substrate support disposed in the processing volume; a plasma source coupled to the processing volume; a steam source fluidly coupled to the processing volume; and a substrate heater. A method of processing a semiconductor substrate includes: initiating conformal radical oxidation of high aspect ratio structures of the substrate comprising: heating the substrate; and exposing the substrate to steam; and conformally oxidizing the substrate. A semiconductor device includes a silicon and nitrogen containing layer; a feature formed in the silicon and nitrogen containing layer having an aspect ratio of at least 40:1; and an oxide layer on the face of the feature having a thickness in a bottom region of the silicon and nitrogen containing layer that is at least 95% of a thickness of the oxide layer in a top region.