Etching Method for Silicon Nitride 3D Patterns
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Solution Overview
Problem
Existing etching methods struggle to form highly precise three-dimensional patterns with multiple end surfaces of different heights due to issues with gas deposition properties, leading to non-uniform widths and unsuccessful pattern formation.
Innovation Solution
An etching method involving a series of processes including conformal film formation and selective anisotropic etching using specific gas sequences, such as aminosilane-based and fluorocarbon-based gases, to achieve precise control over end surface exposure and etching, allowing for the formation of uniform silicon oxide films and subsequent anisotropic etching atomic layer by atomic layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an etching gas having relatively high deposition property is used, then a deposit is generated at a region of a relatively high aspect ratio among grooves of the pattern formed by etching, but anisotropic etching with high precision cannot be achieved
Solution Approach 1:
The patent segments the etching process into multiple sequential steps with different gas compositions. The first step uses a fluorocarbon-based gas for initial etching, followed by a second step using a different fluorocarbon-based gas or mixed gas for precision etching. This segmentation allows each step to have optimized gas properties, preventing deposit accumulation while maintaining etching precision.
Solution Approach 2:
The patent employs periodic alternation between different etching gas compositions in sequential steps. The first etching step uses one gas composition, then the second etching step uses a different composition. This periodic change in gas properties prevents continuous deposit formation while maintaining precise anisotropic etching control throughout the process.
2Manufacturing precision
If an etching gas having relatively low deposition property is used, then etching having a relatively low selectivity is performed, but the grooves of the pattern have non-uniform widths according to denseness and sparseness of the pattern
Solution Approach 1:
The patent divides the etching process into two segmented steps with different gas compositions. The first step uses a fluorocarbon-based gas with appropriate deposition properties to establish selective etching, while the second step uses a different gas composition to achieve uniform pattern formation. This segmentation allows each step to optimize for its specific function, achieving both selectivity and uniformity.
Solution Approach 2:
The patent changes the chemical composition parameters of the etching gas between steps. The first etching step uses one fluorocarbon-based gas composition, while the second etching step uses a different composition or mixed gas. This parameter change optimizes the balance between deposition property and etching selectivity for each step, ensuring both uniform pattern formation and reliable selectivity.
3Manufacturing precision
If a mixed gas of CH3F gas and O2 gas is used with O2/CH3F ratio from 4 to 9, then etching of silicon nitride film can be performed, but highly precise anisotropic etching with atomic layer control cannot be achieved
Solution Approach 1:
The patent segments the etching process into multiple steps, each using simpler fluorocarbon-based gases rather than complex mixed gases like CH3F/O2. The first step uses one fluorocarbon-based gas, and the second step uses another fluorocarbon-based gas or mixed gas with simpler composition. This segmentation achieves atomic layer precision while avoiding the complexity of high-ratio mixed gas systems.
4Manufacturing precision
If multi-stage processing is performed with anisotropic etching on low-k material followed by isotropic etching on SiN, then spacer formation can be achieved, but highly precise anisotropic etching of multiple end surfaces at different heights cannot be performed
Solution Approach 1:
The patent segments the etching process into two distinct sequential steps, each optimized for specific requirements. The first etching step uses a fluorocarbon-based gas to selectively expose certain end surfaces, and the second etching step uses a different fluorocarbon-based gas or mixed gas to precisely etch the exposed surfaces at atomic layer precision. This segmentation achieves multi-end surface precision without requiring complex multi-material processing.
Solution Approach 2:
The patent changes the gas composition parameters between etching steps to achieve different etching characteristics. The first step uses one fluorocarbon-based gas composition optimized for selective exposure, while the second step uses a different composition optimized for atomic layer precision etching. This parameter change enables precise control of multiple end surfaces at different heights without complex multi-stage processing.
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
Enables the successful formation of three-dimensional patterns with high precision and uniformity by selectively exposing and etching end surfaces, overcoming previous challenges with gas deposition and selectivity.
Implementation Method 1
a fourth process of supplying a first gas containing an organic-containing aminosilane-based gas into a space in which the processing target object is placed; a fifth process of forming a silicon oxide film on each of the end surfaces by repeating a sequence including: a process of generating plasma of a second gas containing oxygen atoms in the space in which the processing target object is placed
Implementation Method 2
a process of generating plasma of a second gas containing oxygen atoms in the space in which the processing target object is placed
Implementation Method 3
a sixth process of supplying a third gas containing a fluorocarbon-based gas into the space in which the processing target object is placed; a seventh process of generating plasma of the third gas in the space in which the processing target object is placed
Data Source
AI summary
An etching method of etching a processing target object is provided. The processing target object has a supporting base body and a processing target layer. The processing target layer is provided on a main surface of the supporting base body and includes protrusion regions. Each protrusion region is extended upwards from the main surface, and an end surface of each protrusion region is exposed when viewed from above the main surface. The etching method includes a first process of forming a film on the end surface of each protrusion region; a second process of selectively exposing one or more end surfaces by anisotropically etching the film formed through the first process; and a third process of anisotropically etching the one or more end surfaces exposed through the second process atomic layer by atomic layer. The processing target layer contains silicon nitride, and the film contains silicon oxide.