Etching Endpoint Detection Stabilization via Inert Gas Plasma
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Solution Overview
Problem
The formation of polymer byproducts in the etching process using halogen-containing gases interferes with endpoint detection, leading to inaccurate endpoint determination and damage to underlying material layers during semiconductor processing.
Innovation Solution
An etching method that includes an etching environment adjustment process using inert gas plasma treatment to stabilize endpoint detection signals, allowing for real-time monitoring and precise control of the etching process by using inert gases like helium, neon, or their mixtures, which are introduced into the etching chamber to adjust the plasma environment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If halogen-containing gas is used for etching, then etching performance is improved, but polymer byproduct formation interferes with endpoint detection
Solution Approach 1:
The patent introduces an intermediary cleaning step using oxygen plasma or oxygen-containing gas between etching steps. This intermediary process removes polymer byproducts from the chamber walls and substrate surface without affecting the etching performance of the halogen-containing gas, thereby restoring endpoint detection accuracy while maintaining high etching productivity
Solution Approach 2:
The patent uses oxygen plasma or oxygen-containing gas to create a temporary oxidizing environment that converts polymer byproducts (composed of carbon, fluorine, nitrogen, and oxygen) into volatile compounds that can be removed by vacuum pumping. This inert atmosphere approach cleans the chamber without introducing contaminants that would affect subsequent etching processes
2Productivity
If polymer byproduct accumulates in the etching chamber, then endpoint detection is interfered, but continuing etching damages underlying material layer
Solution Approach 1:
The patent implements periodic cleaning cycles interspersed between etching steps. Instead of continuous etching, the process alternates between halogen-containing gas etching and oxygen plasma cleaning. This periodic action prevents polymer accumulation from reaching harmful levels while maintaining continuous productivity, and prevents underlying material damage by ensuring accurate endpoint detection throughout the process
Solution Approach 2:
The patent maintains continuous useful action by designing the cleaning process to be integrated within the overall etching sequence. The oxygen plasma cleaning step is performed in-situ without breaking vacuum or requiring chamber opening, thus maintaining continuous productive operation while preventing the accumulation of harmful polymer byproducts
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
The method stabilizes endpoint detection signals, enlarges the process window for endpoint control, and prevents over-etching by ensuring accurate termination of the etching process, thereby protecting the underlying material layers.
Implementation Method 1
The plasma used in the etching process is often generated from a halogen containing gas mixture
Implementation Method 2
the reacting gas molecule is ionized by plasma to form ions that are reactive with the thin film material
Data Source
AI summary
The invention is directed to an etching method for patterning a first material layer over a second material layer to expose a portion of the second material layer. The etching method comprises steps of performing a first etching process to remove a portion of the first material layer in an etching chamber and then performing an etching environment adjustment process in the etching chamber. A second etching process is performed on the first material layer and, meanwhile, a real-time etching monitor process is performed for generating an endpoint detection spectrum subsequent to the etching environment adjustment process, wherein at least one of signals of the endpoint detection spectrum is stabilized by the inert gas plasma treatment.