Plasma-Free Oxide Etching Using Selective Fluorine Chemistry
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Solution Overview
Problem
Existing etching methods for metal oxides and semimetal oxides are complex and lack selectivity, often requiring multiple steps and non-selectively etching unintended materials, such as polysilicon or silicon nitride, due to the use of plasma etching processes.
Innovation Solution
An etching method using a fluorine-containing compound with a functional group, such as carbonyl fluoride, that reacts with oxides without generating plasma within the chamber, allowing for selective etching of metal or semimetal oxides by forming volatile compounds while sparing other materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma etching is used to etch metal oxides, then etching can be performed, but the process becomes complex and requires multiple steps
Solution Approach 1:
The patent extracts the plasma generation step from the etching process, using only the chemical reaction between fluorine-containing gas and metal oxide without plasma activation. This eliminates the complexity of plasma generation equipment and control while maintaining etching capability through direct chemical vapor deposition mechanisms.
Solution Approach 2:
The patent segments the traditional two-step plasma etching process (fluorination followed by organic reaction) into a single integrated step using fluorine-containing compounds that perform both functions simultaneously, reducing process complexity while maintaining etching effectiveness.
2Productivity
If plasma etching is used to etch metal oxides, then etching can be performed, but selective etching becomes difficult
Solution Approach 1:
The patent applies local quality by using fluorine-containing compounds that specifically react with metal oxide surfaces while leaving other materials unaffected. The chemical reactivity is localized to oxide materials, providing high selectivity without requiring plasma activation that would affect multiple material types.
Solution Approach 2:
The patent changes the chemical parameters by using specific fluorine-containing compounds with controlled reactivity toward metal oxides. By adjusting gas composition, flow rate, and temperature, the etching process achieves high selectivity for oxide materials while sparing polysilicon, silicon nitride, and other non-oxide materials.
3Productivity
If conventional etching gases are used, then etching can be performed, but unintended materials such as polysilicon or silicon nitride are also etched
Solution Approach 1:
The patent converts the potential harm of non-selective etching into a benefit by using fluorine-containing compounds that naturally exhibit selective reactivity. The chemical properties of these compounds inherently protect unintended materials (polysilicon, silicon nitride) while effectively etching metal oxides, turning a selectivity challenge into a selective advantage.
Solution Approach 2:
The fluorine-containing compound acts as an intermediary that mediates between the etching target (metal oxide) and the unwanted materials. It selectively interacts with oxide materials through chemical bonding while being inert toward other materials, providing a protective intermediary layer of selectivity.
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 one-step, plasma-free etching of metal or semimetal oxides with high selectivity, reducing process complexity and preventing unnecessary material etching, thus improving manufacturing efficiency and cost-effectiveness in semiconductor production.
Implementation Method 1
the metal oxide is fluorinated with a fluorine-containing gas to form a metal fluoride
Implementation Method 2
the metal fluoride is reacted with an organic substance to form a volatile metal compound, which is then volatilized
Data Source
AI summary
An etching method capable of selectively etching an oxide, which method includes an etching step in which an etching target (12) including an oxide is placed in a chamber (10), and the oxide included in the etching target (12) is etched in the chamber (10) using an etching gas containing a fluorine-containing compound including a functional group represented by the chemical formula below:wherein a symbol * means a bonding point with another atom or atomic group. The oxide is at least one of a metal oxide or a semimetal oxide. Further, in the etching step, the etching is performed without generating a plasma of the etching gas in the chamber (10).