Iodine Fluorocarbon Etching for High-Aspect-Ratio Silicon Patterns
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Solution Overview
Problem
Traditional etch chemistries struggle to achieve high aspect ratios and vertical profiles in 3D NAND applications due to insufficient etch resistant polymer deposition on sidewalls, leading to bowing, pattern collapse, and increased roughness, while also lacking selectivity among various materials like amorphous carbon, silicon nitride, and polysilicon.
Innovation Solution
The use of iodine-containing etching compounds with the formula CnHxFyIz, where 4≤n≤10, 0≤x≤21, and 1≤z≤4, introduced into a reaction chamber, activated to produce iodine ions that selectively etch silicon-containing films, enhancing selectivity and etch resistance, and optionally combined with oxidizers and inert gases to maintain high aspect ratios and vertical profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional etch chemistries (cC4F8, C4F6, CF4) are used, then etching process is simple, but insufficient etch resistant polymer deposition on sidewalls leads to bowing, pattern collapse, and increased roughness
Solution Approach 1:
The patent changes the chemical composition parameters of the etch gas by introducing iodine-containing compounds (CnHxFyIz) with specific carbon chains (4-10 carbons) and iodine content (1-4 atoms). This chemical parameter change enables formation of etch-resistant polymer sidewalls while maintaining vertical profiles and preventing pattern collapse, directly resolving the contradiction between manufacturing precision and chemistry complexity.
Solution Approach 2:
The patent uses composite etch chemistry combining iodine-containing compounds with traditional fluorocarbon etchants. This composite approach leverages the polymer deposition capability of fluorocarbons and the etch resistance enhancement from iodine, achieving both vertical profiles and pattern integrity without requiring completely new chemistry systems.
2Manufacturing precision
If traditional etch chemistries are used, then process is simpler, but selectivity among materials (a-C, SiN, p-Si) is insufficient
Solution Approach 1:
The patent modifies the etch chemistry by incorporating iodine-containing compounds with specific molecular structures (CnHxFyIz where n=4-10). This chemical parameter change enables differential etching rates among a-C, SiN, and p-Si materials, achieving the required material selectivity while maintaining process controllability.
3Manufacturing precision
If high aspect ratio etching (200:1) is achieved, then vertical profiles are maintained, but sidewall etching of mask layer increases causing bowing
Solution Approach 1:
The patent introduces iodine-containing etch compounds as an intermediary that forms protective polymer layers on sidewalls during etching. These polymer intermediaries prevent direct exposure of the mask layer to etching radicals, reducing sidewall etching and mask damage while enabling high aspect ratio (200:1) vertical profiles to be achieved without bowing.
Solution Approach 2:
The patent changes the chemical reactivity parameters by using iodine-containing compounds instead of traditional fluorocarbons. This parameter change modifies the etching mechanism to be more selective and less damaging to mask layers, enabling high aspect ratio etching without the harmful sidewall etching and bowing effects.
4Manufacturing precision
If iodine-containing etching compounds are used, then etch resistance and selectivity improve, but global warming potential increases
Solution Approach 1:
The patent optimizes the molecular parameters of iodine-containing compounds by controlling carbon chain length (4-10 carbons) and iodine content (1-4 atoms per molecule). This parameter optimization achieves the required etch resistance and selectivity while managing the environmental impact, as the specific molecular structure influences both performance and GWP characteristics.
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
The method achieves high aspect ratios up to 200:1 with minimal bowing and roughness, improves selectivity among various materials, and increases etch resistance by doping iodine into the mask layer, reducing damage and maintaining pattern integrity during etching.
Implementation Method 1
activating a plasma to produce an activated iodine-containing etching compound
Implementation Method 2
activating a plasma to produce an activated iodine-containing etching compound capable of etching the silicon-containing film
Implementation Method 3
allowing an etching reaction to proceed between the activated iodine-containing etching compound and the silicon-containing film to selectively etch the silicon-containing film
Data Source
AI summary
Disclosed are methods for etching a silicon-containing film to form a patterned structure, methods for reinforcing and/or strengthening and/or minimizing damage of a patterned mask layer while forming a patterned structure and methods for increasing etch resistance of a patterned mask layer in a process of forming a patterned structure. The methods include using an activated iodine-containing etching compound having the formula CnHxFyIz, wherein 4≤n≤10, 0≤x≤21, 0≤y≤21, and 1≤z≤4 as an etching gas. The activated iodine-containing etching compound produces iodine ions, which are implanted into the patterned hardmask layer, thereby strengthening the patterned mask layer.