Plasma Etching Gas Composition for Selective Tin-Indium Oxide Etching
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Solution Overview
Problem
Existing plasma etching methods fail to achieve excellent etching selectivity for metal oxides such as tin and indium oxides compared to non-etching objects like silicon-containing compounds and photoresists.
Innovation Solution
A plasma etching method using an etching gas containing an unsaturated compound with fluorine and bromine atoms, applied with a bias power exceeding 0 W, selectively etches tin and indium oxides by reacting with the etching object while minimizing reaction with non-etching objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching gases (hydrogen bromide or hydrogen iodide) are used, then etching of metal oxide can be performed, but etching selectivity between metal oxide and non-etching objects is insufficient
Solution Approach 1:
The patent changes the chemical composition parameters of the etching gas from conventional hydrogen bromide or hydrogen iodide to a mixed gas containing carbon tetrafluoride (1-50 vol%), sulfur hexafluoride (1-50 vol%), and hydrogen bromide (1-50 vol%). This parameter change in gas composition enables selective etching of metal oxide while minimizing etching of mask and photoresist materials, achieving the desired etching selectivity.
2Productivity
If etching gas contains hydrogen bromide or hydrogen iodide, then metal oxide etching can proceed, but selectivity ratio between etching object and non-etching object deteriorates
Solution Approach 1:
The patent uses a composite etching gas mixture combining carbon tetrafluoride, sulfur hexafluoride, and hydrogen bromide in specific proportions. This composite gas formulation leverages the complementary properties of each component: carbon tetrafluoride and sulfur hexafluoride provide selective chemical reaction with metal oxide, while hydrogen bromide enhances etching rate, achieving both high productivity and high selectivity ratio simultaneously.
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 achieves a high etching selectivity ratio of 2:1 or more, allowing precise etching of metal oxides without significant etching of non-etching materials, enhancing the manufacturing process for semiconductor elements.
Implementation Method 1
an etching step of bringing an etching gas containing an unsaturated compound having a fluorine atom and a bromine atom in the molecule thereof into contact with a member to be etched including an etching object to be etched by the etching gas and a non-etching object not to be etched by the etching gas in the presence of plasma
Implementation Method 2
performing etching while applying a bias power exceeding 0 W to a lower electrode supporting the member to be etched
Data Source
AI summary
A plasma etching method capable of selectively etching an etching object containing oxide of at least one of tin and indium compared to a non-etching object. The plasma etching method includes: an etching step of bringing an etching gas containing an unsaturated compound having a fluorine atom and a bromine atom in the molecule thereof into contact with a member to be etched including an etching object to be etched by the etching gas and a non-etching object not to be etched by the etching gas in the presence of plasma, performing etching while applying a bias power exceeding 0 W to a lower electrode supporting the member to be etched, and selectively etching the etching object compared to the non-etching object. The etching object contains oxide of at least one of tin and indium and the non-etching object contains at least one of a silicon-containing compound and a photoresist.