Fluorobutene Etching Gas for High-Selectivity Silicon Patterning
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Solution Overview
Problem
Existing etching methods using hexafluoroisobutene often result in insufficient etching selectivity between silicon compounds and mask materials during semiconductor production.
Innovation Solution
An etching gas containing fluorobutene with controlled concentrations of metal impurities like copper, zinc, manganese, and silicon, and alkali/alkaline earth metals, which are kept below 5000 ppb by mass, is used to selectively etch silicon compounds while minimizing the dissociation of carbon-carbon double bonds, thereby enhancing etching selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hexafluoroisobutene is used as etching gas, then polymer film formation on mask is enhanced, but etching selectivity becomes insufficient
Solution Approach 1:
The patent changes the chemical parameters of the etching gas by specifying fluorobutene with controlled metal impurity concentrations (5000 ppb by mass or less). This parameter optimization resolves the contradiction by achieving high etching selectivity (10 or more) while preventing excessive polymer film formation that would harm the mask.
Solution Approach 2:
The patent applies local quality control by specifically targeting metal impurity concentrations in the etching gas. By controlling copper, zinc, manganese, cobalt, and silicon impurities to 5000 ppb or less, the patent creates optimal local conditions for high selectivity etching without the harmful side effects of polymer formation.
2Reliability
If metal impurity concentration is reduced, then etching selectivity is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by specifying metal impurity removal processes before the etching step. The metal impurity removing step is performed in advance to ensure impurity concentrations are 5000 ppb by mass or less, thereby achieving high etching selectivity without requiring complex real-time control during etching.
3Manufacturing precision
If etching selectivity is increased to 10 or more, then manufacturing precision is improved, but processing time increases
Solution Approach 1:
The patent optimizes multiple parameters simultaneously: fluorobutene composition, metal impurity concentrations (5000 ppb or less), and process conditions. This multi-parameter optimization achieves high etching selectivity (10 or more) for precise pattern formation while maintaining efficient processing speed suitable for semiconductor manufacturing.
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 etching method achieves high selectivity ratios of 10 or more between etching and non-etching objects, allowing precise processing of semiconductor devices with improved miniaturization and integration capabilities.
Implementation Method 1
fluorobutene represented by a general formula C4HxFy, in which x is 1 or more and 7 or less, y is 1 or more and 7 or less, and x+y is 8... selectively etching the etching object as compared with the non-etching object, in which the etching object contains silicon
Implementation Method 2
the etching gas contains or does not contain at least one of copper, zinc, manganese, cobalt, and silicon as metal impurities, and the sum of the concentrations of copper, zinc, manganese, cobalt, and silicon when contained is 5000 ppb by mass or less
Data Source
AI summary
An etching gas and an etching method capable of selectively etching an etching object containing silicon as compared with a non-etching object. The etching gas contains fluorobutene represented by a general formula C4HxFy, in which x is 1 or more and 7 or less, y is 1 or more and 7 or less, and x+y is 8. The etching gas contains or does not contain at least one of copper, zinc, manganese, cobalt, and silicon as metal impurities, and the sum of the concentrations of copper, zinc, manganese, cobalt, and silicon when contained is 5000 ppb by mass or less. The etching method includes an etching step of bringing the etching gas into contact with a member to be etched (12) having an etching object and a non-etching object, and selectively etching the etching object as compared with the non-etching object. The etching object contains silicon.