Substrate Plasma Etching with Dynamic Fluorine Ratio Control
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Solution Overview
Problem
Existing semiconductor fabrication processes face challenges in effectively controlling etching selectivity, particularly for materials like silicon-germanium, which requires higher selectivity than silicon, and process variations necessitate varied control of etching speed and critical dimension precision.
Innovation Solution
A substrate processing method and apparatus that dynamically controls etching selectivity by generating a process etchant from a preliminary etchant composed of first and second etchants through plasma ignition, adjusting their composition ratio, and using a fluorine-contained gas to create a controlled etching environment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional plasma etching is used, then etching process can be performed, but etching selectivity between different materials (e.g., SiGe vs Si) cannot be effectively controlled
Solution Approach 1:
The patent applies dynamics by enabling real-time adjustment of etchant composition ratios during the etching process. The plasma etching system dynamically controls the ratio of different etchants (e.g., F radicals and F2) to adaptively optimize etching selectivity for different materials like SiGe and Si, allowing the process to respond to varying material properties rather than using a fixed composition.
Solution Approach 2:
The invention changes physical and chemical parameters of the etching process by controlling the composition ratio of etchants in the plasma. By adjusting parameters such as gas flow rates, pressure, and power to modify etchant composition, the system achieves different etching selectivities for various materials, enabling precise control over etching characteristics.
2Manufacturing precision
If fixed composition etchant is used, then process simplicity is maintained, but dynamic control of etching speed and critical dimension precision is limited
Solution Approach 1:
The patent implements feedback control mechanisms that monitor etching progress and material removal rates, then adjust etchant composition ratios in real-time. This feedback loop enables precise control of critical dimensions by continuously optimizing the etching process based on actual process conditions and measured outcomes.
Solution Approach 2:
The system transitions from static etchant composition to dynamic adjustment, where the ratio of etchants is continuously modified during processing. This dynamic control allows precise regulation of etching speed and critical dimension accuracy while adapting to process variations.
3Adaptability or versatility
If single etchant plasma is used, then process simplicity is maintained, but selective etching of multiple film types with different selectivity requirements is difficult
Solution Approach 1:
The patent uses a composite etching approach by combining multiple etchants (e.g., F radicals and F2) in controlled ratios within the plasma. This composite etchant system provides enhanced versatility for etching different film types with varying selectivity requirements, as each etchant component contributes different chemical reactivity and selectivity characteristics.
Solution Approach 2:
The invention segments the etching function by using distinct etchant components with different selectivity profiles. By dividing the etching action into multiple chemical components that can be independently controlled, the system achieves selective etching of different materials while maintaining operational control through unified plasma 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 selective etching of various film types with precise control over etching selectivity, enhancing process stability and accuracy in semiconductor device fabrication.
Implementation Method 1
generating a preliminary etchant, which includes first and second etchants, from the process gas through plasma ignition
Implementation Method 2
providing second F radicals in the processing chamber, processing the substrate with the process etchant
Data Source
AI summary
A substrate processing apparatus, a substrate processing method, and a method of fabricating a semiconductor device are provided. The substrate processing method includes providing a process gas, generating a preliminary etchant, which includes a first etchant and a second etchant, from the process gas through plasma ignition, generating a process etchant by controlling a composition ratio of the preliminary etchant, and performing a selective etching of the substrate with the process etchant.