Atomic Layer Cobalt Etching with Chlorine and Acetylacetone
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Solution Overview
Problem
The high cost of manufacturing 3D NAND flash devices due to the expensive materials used in the atomic layer etching of cobalt films, and the resulting surface roughness that leads to device defects and increased leakage current.
Innovation Solution
A substrate processing method involving surface modification with chlorine gas followed by etching with acetylacetone gas at the atomic layer level, reducing manufacturing costs and surface roughness by repeating cycles while maintaining the substrate at 125° C to 175° C, and using a substrate processing apparatus with a chamber, plasma generation unit, and gas supply system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If hexafluoroacetylacetone (Hhfac) is used for atomic layer etching of cobalt film, then etching capability is achieved, but manufacturing cost increases significantly
Solution Approach 1:
The patent replaces expensive hexafluoroacetylacetone (Hhfac) with cheaper acetylacetone (Hacac) as the etching material. Although Hacac is less effective individually, it achieves comparable etching results when used in combination with chlorine surface modification, thereby significantly reducing manufacturing costs while maintaining etching capability
Solution Approach 2:
The patent combines chlorine surface modification with acetylacetone etching to create a composite processing approach. The chlorine treatment modifies the cobalt film surface to enhance subsequent Hacac etching efficiency, achieving results comparable to expensive Hhfac through a two-material combination process
2Device complexity
If conventional etching materials are used, then etching process is simpler, but surface roughness increases leading to device defects
Solution Approach 1:
The patent divides the etching process into two distinct stages: surface modification with chlorine and subsequent etching with acetylacetone. This segmentation allows each step to be optimized independently, with chlorine preparing the surface and Hacac performing the controlled etching, resulting in reduced surface roughness and fewer device defects
Solution Approach 2:
The patent applies chlorine surface modification as a preliminary step before the actual etching process. This preliminary action prepares the cobalt film surface by creating a modified layer that is more susceptible to controlled etching by Hacac, thereby achieving smoother surfaces and reducing defects
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 method lowers the manufacturing cost of devices by using cheaper acetylacetone instead of hexafluoroacetylacetone and reduces surface roughness, thereby reducing device defects and improving etching selectivity.
Implementation Method 1
a surface modification step of modifying a surface of the thin film by supplying a first gas including chlorine (Cl) to a processing space
Implementation Method 2
an etching step of etching the modified thin film by supplying a second gas including acetylacetone (Hacac) to the processing space
Implementation Method 3
the surface modification step to the second purge step may be performed in a state in which the substrate is heated to a predetermined temperature
Data Source
AI summary
Proposed are a substrate processing method and a substrate processing apparatus. A substrate processing method according to an embodiment is for etching a thin film formed on a substrate at the atomic layer level, and includes a surface modification step of modifying a surface of the thin film by supplying a first gas including chlorine (Cl) to a processing space of a chamber in which the substrate is placed, a first purge step of removing the first gas remaining in the processing space by supplying a purge gas to the processing space, an etching step of etching the modified thin film by supplying a second gas including acetylacetone (Hacac) to the processing space, and a second purge step of removing the second gas remaining in the processing space by supplying the purge gas to the processing space.