Fluorobutene Etching Gas for High-Selectivity Silicon Etching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing etching methods using hexafluoroisobutene often result in insufficient etching selectivity due to excessive polymer film formation on the etching object, reducing the effectiveness of silicon compound etching in semiconductor production.
Innovation Solution
An etching gas containing fluorobutene with controlled concentrations of alkali metals and alkaline earth metals, along with other metal impurities, is used to selectively etch silicon compounds by minimizing polymer film formation, ensuring high etching selectivity through precise control of metal impurity levels and gas composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hexafluoroisobutene is used as etching gas, then etching capability is improved, but polymer film formation increases causing insufficient etching selectivity
Solution Approach 1:
The patent changes the chemical parameters of the etching gas by specifying fluorobutene with controlled metal impurity levels (alkali metals and alkaline earth metals at 5000 ppb by mass or less). This parameter control prevents excessive polymer film formation while maintaining etching capability, thereby resolving the contradiction between etching productivity and etching selectivity.
2Reliability
If polymer film forms on mask during etching, then mask protection is improved, but etching selectivity becomes insufficient
Solution Approach 1:
The patent controls the metal impurity content (alkali metals and alkaline earth metals at 5000 ppb by mass or less) in the fluorobutene etching gas to optimize polymer film formation. This controlled approach ensures sufficient mask protection while preventing excessive polymer accumulation that would compromise etching selectivity, thus resolving the contradiction between mask protection reliability and etching selectivity precision.
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 a high etching selectivity ratio of 10 or more, allowing for accurate processing of semiconductor devices with improved miniaturization and integration capabilities.
Implementation Method 1
fluorobutene represented by a general formula C4HxFy reacts with silicon compounds containing silicon to selectively etch the etching object
Implementation Method 2
fluorobutene reacts and forms a polymer during etching, and a film of the polymer covers and protects a mask
Data Source
AI summary
There are provided 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 alkali metals and alkaline earth metals as metal impurities, and the sum of the concentrations of alkali metals and alkaline earth metals 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.