Gas Flow Rate Stability During Etching Gas Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing gas supply systems for semiconductor manufacturing struggle to prevent hunting in gas flow rates when switching between etching and deposition gases, leading to instability in etching processes.
Innovation Solution
A method where a small amount of the gas needed before switching, but not needed after, is continuously supplied during the transition, using existing devices like mass flow controllers to control flow rates, thereby preventing hunting and stabilizing the gas flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a valve of a mass flow controller is controlled to change from a closed state to an opened state to switch gas species, then gas species switching is achieved, but hunting (overshoot) in gas flow rate occurs
Solution Approach 1:
The patent applies preliminary action by continuously supplying a small amount of the gas that will be switched away from, before and during the switching process. This prevents the complete closure and subsequent sudden opening of the MFC valve, thereby avoiding hunting (overshoot) in gas flow rate while still achieving gas species switching. The small continuous supply acts as a buffer that smooths the transition.
Solution Approach 2:
The patent uses an intermediary approach by introducing a small continuous supply of the outgoing gas as a mediator between the closed and fully open valve states. This intermediary flow prevents the abrupt changes that cause hunting, while the MFC valve still performs the primary function of switching between different gas species.
2Reliability
If a stable step of about 5 seconds is performed before performing a process after switching, then stability of the process after switching is achieved, but productivity decreases
Solution Approach 1:
The patent eliminates the need for a stable step by maintaining continuous useful action through the small continuous supply of the outgoing gas. This continuous supply prevents flow rate hunting and ensures stable gas flow conditions are maintained throughout the switching process, allowing the etching process to proceed immediately without waiting for a stable step period.
Solution Approach 2:
By performing the preliminary action of continuously supplying a small amount of the outgoing gas, the system pre-prevents the hunting that would otherwise require a stable step to resolve. This allows the process to transition directly into the etching operation without the productivity-reducing waiting period.
3Reliability
If additional valves or pipes are added to prevent hunting during gas switching, then gas flow rate stability is improved, but device complexity increases
Solution Approach 1:
The patent applies self-service by using the existing MFC valve and gas supply infrastructure to prevent hunting, without requiring additional valves or pipes. The small continuous supply of the outgoing gas is achieved by adjusting the existing MFC's output, allowing the system to solve its own stability problem using its own components.
Solution Approach 2:
The patent changes the parameter of gas flow rate by introducing a small continuous supply of the outgoing gas, rather than changing the physical structure of the gas supply system. This parameter-based solution maintains stability while avoiding the complexity of additional hardware components.
Data Source
AI summary
A method of supplying an etching gas includes: supplying a first etching gas used in an etching process into a processing container; and supplying a second etching gas used in the etching process into the processing container, in which, when the first etching gas and the second etching gas are switched therebetween, only a small amount of a gas, which is needed as an etching gas before the switching and is not needed as an etching gas after the switching, is continuously supplied into the processing container.