Remote Plasma Oxidation for Low-k Spacer Etching
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Solution Overview
Problem
Conventional etching methods fail to properly remove spacer layers with low dielectric constants, such as SiOC, SiON, and SiOCN, used in next-generation transistors, as they have stable chemical properties, making it difficult to achieve desired etching without damaging the channel.
Innovation Solution
A method involving the formation of an oxide layer on the spacer layer using remote plasma-activated oxygen-containing gases, followed by selective etching of the oxide layer using fluorine-containing gases, allowing for controlled and isotropic removal of the spacer layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional etching methods are used on spacer layers with low dielectric constants, then the etching process is simple, but the etching cannot be properly performed due to stable chemical properties
Solution Approach 1:
An oxide layer is formed on the spacer layer surface before etching through plasma oxidation. This preliminary oxidation transforms the chemically stable low-k material into an oxide that is susceptible to subsequent etching, enabling effective removal while preserving the underlying structure
Solution Approach 2:
The chemical composition of the spacer layer surface is changed by converting it to an oxide layer. This parameter change in material composition enables the etching process to work effectively on materials that would otherwise be resistant to conventional etching methods
2Manufacturing precision
If etching is performed to remove the spacer layer, then the spacer layer can be removed, but the channel may be damaged
Solution Approach 1:
The oxide layer serves as an intermediary between the etching process and the underlying channel structure. It allows selective etching of the spacer layer while protecting the channel from direct exposure to harsh etching conditions, preventing damage
Solution Approach 2:
The oxide layer is formed selectively on the spacer layer surface, creating a localized region with different etching properties. This enables selective removal of the oxide-coated spacer layer while leaving the channel and other structures intact
3Adaptability or versatility
If the spacer layer is removed to expose side surfaces, then subsequent processes like epitaxial growth can be facilitated, but the etching must be highly selective and controlled
Solution Approach 1:
The oxide layer is formed as a preliminary step that enables subsequent selective etching. This preparation allows for precise control of the etching process to expose side surfaces with the required precision for epitaxial growth and other follow-up processes
Solution Approach 2:
By changing the surface composition to oxide, the etching characteristics are fundamentally altered, enabling high selectivity and precision in removing the spacer layer while exposing side surfaces with controlled morphology suitable for subsequent 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
This approach enables precise and isotropic etching of spacer layers with low dielectric constants, ensuring the desired thickness is achieved without damaging the channel, allowing for the exposure of side surfaces and facilitating subsequent processes like epitaxial growth.
Implementation Method 1
forming an oxide layer on a surface layer of a spacer layer based on an oxygen-containing gas radicalized using remote plasma
Implementation Method 2
removing the formed oxide layer by etching
Data Source
AI summary
A method for processing a substrate on which silicon layers and silicon germanium layers are alternately disposed, includes: forming an oxide layer on a surface layer of a spacer layer based on an oxygen-containing gas radicalized using remote plasma, wherein the spacer layer having a low dielectric constant is formed at least on side surfaces of the silicon layers and the silicon germanium layers; and removing the formed oxide layer by etching.