Nitrogen-Containing Hydrofluorocarbon Etching for 3D NAND
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Solution Overview
Problem
Current etching technologies face challenges in achieving high selectivity and minimizing damage to photoresist layers during plasma etching of silicon-containing films, particularly in 3D NAND applications, where traditional gases fail to provide vertical profiles and high aspect ratios due to insufficient etch resistant polymer deposition on sidewalls.
Innovation Solution
The use of nitrogen-containing hydrofluorocarbon etching compounds such as 2,2,2-Trifluoroethanamine and 1,1,1,3,3,3-Hexafluoroisopropylamine, which selectively etch dielectric anti-reflective coating layers and alternating silicon-containing layers, depositing a protective polymer layer to maintain vertical profiles and high aspect ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional dry etch gases (CF4, CHF3, C4F8, or C4F6) are used to etch SiON layer, then etching can be performed, but selectivity to photoresist is limited and overhanging/damage occurs on the PR mask layer
Solution Approach 1:
The patent changes the chemical composition parameters of the etching gas by introducing nitrogen-containing hydrofluorocarbons with specific molecular structures (formula HFcCNH2 where a=1-3, b=0-4, c=0-2). This chemical parameter change enables simultaneous achievement of high etching rate, high selectivity (>5:1), and minimal photoresist damage by modifying the etching mechanism to be less damaging while maintaining effectiveness on SiON.
2Shape
If traditional etch gases are used, then etching process can proceed, but vertical profiles and high aspect ratios cannot be achieved due to insufficient etch resistant polymer deposition on sidewalls
Solution Approach 1:
The patent employs nitrogen-containing hydrofluorocarbon compounds that create composite protective polymer layers on sidewalls during etching. These polymer layers have enhanced etch resistance properties that enable formation of vertical profiles with aspect ratios up to 200:1, solving the limitation of traditional gases that cannot provide sufficient sidewall protection for high aspect ratio structures.
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
These compounds provide high selectivity to photoresist and hardmask layers while minimizing damage, achieving vertical etch profiles with aspect ratios up to 200:1 and reducing sidewall roughness, thus enhancing the precision and reliability of 3D NAND and DRAM fabrication processes.
Implementation Method 1
nitrogen-containing hydrofluorocarbon etching compounds such as 2,2,2-Trifluoroethanamine and 1,1,1,3,3,3-Hexafluoroisopropylamine, which selectively etch dielectric anti-reflective coating layers and alternating silicon-containing layers, depositing a protective polymer layer to maintain vertical profiles and high aspect ratios
Implementation Method 2
selectively plasma etching the DARC layer versus the patterned photoresist layer using a hydrofluorocarbon etching compound
Data Source
AI summary
A method for using a hydrofluorocarbon etching compound selected from the group consisting of 2,2,2-Trifluoroethanamine (C2H4F3N), 1,1,2-Trifluoroethan-1-amine (Iso-C2H4F3N), 2,2,3,3,3-Pentafluoropropylamine (C3H4F5N), 1,1,1,3,3-Pentafluoro-2-Propanamine (Iso-C3H4F5N), 1,1,1,3,3-Pentafluoro-(2R)-2-Propanamine (Iso-2R—C3H4F5N) and 1,1,1,3,3-Pentafluoro-(2S)-2-Propanamine (Iso-2S—C3H4F5N), 1,1,1,3,3,3-Hexafluoroisopropylamine (C3H3F6N) and 1,1,2,3,3,3-Hexafluoro-1-Propanamine (Iso-C3H3F6N) to selectively plasma etching silicon containing films, such as a dielectric antireflective coat (DARC) layer (e.g., SiON), alternating SiO/SiN layers, alternating SiO/p-Si layers, versus a photoresist layer and/or a hard mask layer (e.g., amorphous carbon layer), wherein the photoresist layer is reinforced and SiO/SiN and/or SiO/p-Si are etched non-selectively.