Fluorobutene Etching Gas for Selective Silicon Etching
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Solution Overview
Problem
Existing etching gases used in semiconductor production often result in insufficient etching selectivity between silicon compounds and other materials, such as masks, leading to inadequate patterning and removal during dry etching processes.
Innovation Solution
An etching gas containing fluorobutene with controlled concentrations of hydrogen fluoride and carbonyl fluoride impurities, produced through dehydration and deoxidizing treatments, is used to selectively etch silicon compounds while minimizing etching of non-target materials, achieving high etching selectivity by reducing the reactivity with non-etching objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching gases (hexafluoroisobutene, hexafluorobutene, hexafluorobutyne) are used, then etching capability is provided, but etching selectivity between silicon compounds and masks is insufficient
Solution Approach 1:
The patent changes the chemical composition parameters of the etching gas by using fluorobutene (C4HxFy where x+y=8) with specifically controlled impurity levels (HF ≤100 ppm, COF2 ≤100 ppm). This parameter optimization resolves the contradiction by achieving both high etching selectivity for silicon compounds and sufficient etching capability, unlike conventional gases that cannot simultaneously satisfy both requirements
Solution Approach 2:
The patent applies local quality control by strictly limiting the concentration of specific impurities (hydrogen fluoride and carbonyl fluoride) in the etching gas. By controlling the local chemical environment through impurity concentration management, the etching gas achieves selective reaction with silicon compounds while minimizing unwanted reactions with masks, thereby resolving the selectivity-capability contradiction
2Manufacturing precision
If dehydration and deoxidizing treatments are applied to crude fluorobutene, then impurity concentration is reduced, but production process complexity increases
Solution Approach 1:
The patent applies preliminary action by performing dehydration and deoxidizing treatments on crude fluorobutene before it is used as etching gas. By removing water and oxygen in advance, the process prevents the formation of excessive HF and COF2 impurities during storage and use, achieving high purity (HF ≤100 ppm, COF2 ≤100 ppm) through straightforward preprocessing steps rather than complex continuous purification systems
Solution Approach 2:
The patent extracts harmful impurities (water and oxygen) from crude fluorobutene through dehydration and deoxidizing treatments. By removing these specific components that lead to unwanted impurities, the process achieves precise impurity control (HF ≤100 ppm, COF2 ≤100 ppm) through simple extraction operations rather than complex multi-stage purification processes
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 gas achieves selective etching of silicon-containing materials with high selectivity ratios, effectively preventing unwanted etching of masks and other non-etching objects, thereby enhancing the precision and efficiency of semiconductor device fabrication.
Implementation Method 1
the dehydration treatment is treatment of bringing the crude fluorobutene into contact with an adsorbent to cause the adsorbent to adsorb the water
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 hydrogen fluoride as an impurity and the concentration of hydrogen fluoride is 100 ppm 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 which is an object to be etched by the etching gas and a non-etching object which is not an object to be etched by the etching gas, and selectively etching the etching object as compared with the non-etching object. The etching object contains silicon.