HF Vapor Etching Timing via OH Vibration Detection
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Solution Overview
Problem
Conventional etching techniques, such as wet etching and vapor-phase etching using hydrofluoric acid, face inefficiencies due to the need for prolonged moisture supply on the substrate surface, leading to longer processing times and pattern collapse issues in finer semiconductor device patterns.
Innovation Solution
An etching method and apparatus that create a reduced pressure state within a processing chamber, supply vapor to form a water layer on the substrate, and detect OH stretching vibration using infrared spectroscopy to determine the optimal timing for etching with hydrogen fluoride gas, ensuring efficient and timely initiation of the etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vapor is supplied to the substrate surface for a long time to ensure sufficient moisture, then etching quality is improved, but total processing time increases
Solution Approach 1:
The patent employs real-time monitoring of vapor supply using a mass spectrometer to detect the concentration of water vapor in the processing chamber. This feedback mechanism allows the system to automatically determine when sufficient moisture has been supplied to the substrate surface, eliminating the need for prolonged fixed-time vapor supply and enabling precise control of the etching process.
Solution Approach 2:
The patent replaces the conventional mechanical timing-based vapor supply control with a detection-based control system. Instead of relying on predetermined time intervals, the system uses a mass spectrometer to detect vapor concentration and automatically triggers the etching process when the threshold is reached, substituting mechanical timing with instrumental detection and automated control.
2Manufacturing precision
If wet etching is used for etching coating films, then etching capability is sufficient, but pattern collapse occurs due to surface tension
Solution Approach 1:
The patent utilizes phase transition by employing vapor-phase etching instead of liquid-phase wet etching. The water vapor condenses on the substrate surface to form a thin liquid layer that provides the necessary moisture for etching, but the overall process occurs in the vapor phase, eliminating the harmful surface tension effects that cause pattern collapse in conventional wet etching.
Solution Approach 2:
The patent creates a controlled vapor-phase environment that mimics the beneficial moisture effects of wet etching while avoiding its harmful characteristics. By conducting the etching process in a vapor phase with controlled water vapor concentration, the system provides sufficient moisture for chemical reactions without introducing the surface tension problems associated with liquid wet etching.
3Productivity
If the vapor supply step is shortened to improve efficiency, then processing time is reduced, but insufficient moisture prevents proper etching
Solution Approach 1:
The mass spectrometer provides real-time feedback on vapor concentration, allowing the system to optimize the vapor supply duration. The feedback mechanism ensures that the vapor supply continues just long enough to achieve the required moisture level on the substrate surface, then automatically stops and triggers etching, preventing both insufficient and excessive vapor supply.
Solution Approach 2:
The detection system automatically monitors the vapor supply process and self-determines when the optimal moisture level has been achieved. The system uses the mass spectrometer data to autonomously control the timing of the etching process initiation, eliminating the need for external intervention or predetermined timing parameters.
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 minimizes waiting time and improves etching efficiency by ensuring sufficient moisture is present on the substrate surface before etching, reducing processing time and maintaining pattern integrity.
Implementation Method 1
detecting OH stretching vibration in the substrate by infrared spectroscopy
Implementation Method 2
gaseous hydrogen fluoride dissolves in water to generate fluorine ions, which contribute to etching
Data Source
AI summary
An etching method according to the present invention includes a step of creating a reduced pressure state inside of a processing chamber accommodating a substrate, after the step of creating the reduced pressure state, a step of supplying vapor into the processing chamber, after the step of creating the reduced pressure state, a step of supplying an etching gas containing hydrogen fluoride into the processing chamber and etching the coating film formed on the substrate, and in the step of supplying the vapor, a step of detecting OH stretching vibration in the substrate by infrared spectroscopy, in which the step of etching the coating film is performed when the OH stretching vibration of a predetermined threshold value or higher is detected in the substrate. Therefore, the efficiency of the etching process is enhanced.