Pulsed-continuous Etching Gas Delivery via Expansion Chambers
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Solution Overview
Problem
Existing xenon difluoride etching systems face challenges in maintaining a continuous flow of gas when high pressures of additional gases are introduced, as it can cause xenon difluoride to stop flowing through the controller, limiting the etching process.
Innovation Solution
The use of multiple expansion chambers allows for alternating charging and isolation, ensuring a substantially continuous flow of etching gas to the main chamber by switching between them based on pressure and flow control, with inert gases like helium, nitrogen, or argon being used to maintain a constant flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high pressures of additional gases are introduced to improve selectivity and uniformity, then etching quality improves, but xenon difluoride flow stops through the controller
Solution Approach 1:
The system divides the gas delivery path into separate segments: one for xenon difluoride etching gas and another for additional inert gases. This segmentation allows each gas to be controlled independently, preventing the additional gases from blocking the xenon difluoride flow through the controller while still achieving the desired mixing in the etching chamber.
Solution Approach 2:
The patent introduces an intermediary chamber or mixing zone where the xenon difluoride and additional gases are combined after the flow controller. This intermediary space allows high-pressure additional gases to be introduced without interfering with the flow controller's operation, maintaining both flow reliability and etching quality.
2Manufacturing precision
If additional inert gas is mixed into xenon difluoride to improve etching performance, then selectivity and uniformity increase, but the system complexity increases
Solution Approach 1:
The patent combines the additional gas introduction system with the existing xenon difluoride delivery system by integrating the gas mixing function into the etching chamber or by using a common vacuum pump system. This merging approach allows improved etching performance while minimizing additional system complexity.
3Reliability
If pulsed etching method is used to manage gas pressures, then flow control is improved, but etching duration is reduced
Solution Approach 1:
The patent establishes a continuous flow system where xenon difluoride is supplied at a constant low pressure through the flow controller, while additional gases are introduced continuously at higher pressures into the etching chamber. This continuous action eliminates the need for pulsed operation, maintaining reliable flow control while enabling long-duration etching processes.
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 enables long-duration, continuous etching by maintaining a consistent flow of etching gas, improving the etching process by preventing interruptions and ensuring a stable supply of xenon difluoride, even with high-pressure inert gas mixtures.
Implementation Method 1
the xenon difluoride gas reacts with solid materials, such as silicon and molybdenum, such that the materials are converted to a gas phase and removed
Implementation Method 2
xenon difluoride is sublimated from a solid to a gas in an intermediate chamber, referred to as an expansion chamber
Data Source
AI summary
In a system and method of etching a sample disposed in an etching chamber, a plurality of separately stored charges of an etching gas is discharged, one at a time, into a sample etching chamber. The discharge of each charge of etching gas occurs such that a momentary overlap exists in the end discharge of one charge of etching gas with the beginning discharge of another charge of etching gas, whereupon the desired flow of etching gas into the etching chamber is maintained. During discharge of one charge of etching gas, a previously discharged charge of etching gas is recharged. The process of discharging a plurality of separately stored charges of an etching gas, one at a time, and recharging at least one previously discharged charges of etching gas during the discharge of at least one charge of etching gas continues until the sample is etched to a desired extent.