Etching Process Using Fluorine and Inert Gas Mixtures
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Solution Overview
Problem
Current etching gas compositions used in semiconductor production, such as NF3, have high global warming potential and require frequent chamber cleaning, which is costly and environmentally detrimental, necessitating the development of a more environmentally friendly and efficient etching gas mixture for both etching and chamber cleaning.
Innovation Solution
A mixture of fluorine, nitrogen, and argon is used for etching and chamber cleaning, with a preferred fluorine content between 1 and 35 vol.%, allowing for effective etching of inorganic materials and surface cleaning without the need for extensive apparatus tuning, and can be used as a drop-in substitute for NF3 in existing systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If NF3 is used as etching gas, then etching of inorganic materials is achieved, but global warming emission increases significantly
Solution Approach 1:
The patent changes the chemical composition parameters of the etching gas from pure NF3 to a mixture containing F2 (1-35 vol.%, preferably 15-25 vol.%, especially 18-22 vol.%), N2, and Ar. This parameter change maintains etching effectiveness while dramatically reducing the global warming potential by eliminating NF3, which has a GWP of 174, in favor of F2 which has a GWP of 146 but is used in controlled mixtures with inert gases.
Solution Approach 2:
The patent creates a composite gas mixture combining F2 with inert gases (N2 and Ar) to achieve both effective etching of inorganic materials and reduced environmental impact. The composite nature of this gas mixture allows the reactive F2 to perform etching while the inert N2 and Ar dilute the mixture to control reactivity and reduce overall environmental harm compared to pure NF3.
2Reliability
If NF3 is used for chamber cleaning, then cleaning effectiveness is achieved, but cost increases and environmental harm worsens
Solution Approach 1:
The patent modifies the cleaning gas composition from NF3-based mixtures to F2-based mixtures containing 1-35 vol.% F2, N2, and Ar. This parameter change maintains the ability to effectively remove inorganic deposits from chamber walls while reducing environmental harm by eliminating NF3, which contributes to both high cost and high global warming potential.
3Productivity
If fluorine content in the mixture is increased, then etching efficiency increases, but environmental risk increases
Solution Approach 1:
The patent optimizes the fluorine content parameter to a specific range (1-35 vol.%, preferably 15-25 vol.%, especially 18-22 vol.%) rather than using high concentrations. This parameter optimization achieves high etching efficiency through sufficient F2 content while limiting environmental risk by preventing excessive fluorine release. The presence of inert N2 and Ar further mitigates environmental risk by diluting the reactive F2.
4Object-affected harmful factors
If existing systems are converted to use the new gas mixture, then environmental impact is reduced, but apparatus tuning may be required
Solution Approach 1:
The patent develops a gas mixture formulation that is universally applicable to existing plasma etching equipment without requiring fundamental system modifications. The F2/N2/Ar mixture can serve multiple functions (etching different inorganic materials, chamber cleaning) using the same basic equipment, minimizing the need for apparatus tuning while achieving reduced environmental impact.
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 fluorine and inert gas mixture reduces environmental impact, maintains high etching efficiency comparable to or exceeding NF3, and allows for flexible operation of etching and cleaning processes without the need for extensive retuning of equipment, thereby reducing costs and environmental harm.
Implementation Method 1
The treatment with the gas mixture can be performed in the presence of a plasma
Implementation Method 2
a fluorine-containing gas, e.g. NF3, which is decomposed and mixed with certain inert gases
Implementation Method 3
NF3 can be used to etch inorganic coatings like SiON, amorphous Si, SiO2, TiN, TaN or W
Data Source
AI summary
Mixtures of fluorine and inert gases like nitrogen and/or argon can be used for etching of semiconductors, solar panels and flat panels (TFTs and LCDs), and for cleaning of semiconductor surfaces and plasma chambers. Preferably, fluorine is comprised in an amount of 15 to 25 vol.-% in binary mixtures. The gas mixtures can be used as substitute or drop-in for respective mixtures comprising NF3 and permit a very flexible operation of plasma apparatus. For example, apparatus tuned for NF3/Ar mixtures can be operated without further tuning using fluorine and argon, optionally together with nitrogen. The fluorine content is preferably in the range of 1 to 5 vol.-%, if ternary mixtures of fluorine, nitrogen and argon are used.