Low-Impurity Fluorobutene Etching Gas for Silicon Selectivity
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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 incomplete patterning and potential damage to non-targeted objects.
Innovation Solution
An etching gas containing fluorobutene with controlled concentrations of carbonyl fluoride and hydrogen fluoride impurities, produced through dehydration and deoxidizing treatments, is used to selectively etch silicon compounds while minimizing reaction with non-etching objects, thereby enhancing etching selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching gases (hexafluoroisobutene, hexafluorobutene, hexafluorobutyne) are used, then etching capability is achieved, 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 introducing fluorobutene (C4HxFy where x+y=8) with specifically controlled impurity levels (carbonyl fluoride ≤100 ppm, hydrogen fluoride ≤100 ppm). This parameter optimization resolves the contradiction by achieving both high etching capability and high selectivity between silicon compounds and masks, thereby improving manufacturing precision while maintaining reliability
Solution Approach 2:
The patent applies local quality by creating a chemically optimized etching environment where the fluorobutene gas exhibits selective reactivity. The gas composition is tailored to react preferentially with silicon compounds while minimizing reaction with mask materials, achieving high etching selectivity (10:1 or higher) and resolving the contradiction between etching capability and patterning accuracy
2Productivity
If etching gas reacts with non-etching objects (masks), then complete etching of silicon compounds is achieved, but damage to masks and insufficient patterning occurs
Solution Approach 1:
The patent converts the potential harm of gas reactivity into a benefit by carefully selecting fluorobutene with controlled impurity levels. The gas is designed to be highly reactive toward silicon compounds (beneficial) while being inert toward mask materials (avoiding harm). This resolves the contradiction by maintaining high productivity through efficient silicon etching while preventing mask damage, achieving both complete etching and pattern fidelity
3Ease of manufacture
If crude fluorobutene with water and oxygen is used, then gas availability is high, but carbonyl fluoride and hydrogen fluoride impurities are generated reducing selectivity
Solution Approach 1:
The patent applies preliminary action by performing dehydration and deoxidizing treatments on fluorobutene before it is used for etching. These pre-treatment steps remove water and oxygen that would otherwise react to form carbonyl fluoride and hydrogen fluoride impurities. This resolves the contradiction by maintaining ease of manufacture through simple treatment processes while achieving high etching selectivity by preventing impurity formation
Solution Approach 2:
The patent extracts harmful components (water and oxygen) from the fluorobutene gas through dehydration and deoxidizing treatments. By removing these impurities before use, the gas maintains high availability and simplicity of production while achieving the required purity level (carbonyl fluoride ≤100 ppm, hydrogen fluoride ≤100 ppm) for high etching selectivity, thus resolving the contradiction between ease of manufacture and manufacturing 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 gas achieves high selectivity ratios, allowing for precise etching of silicon-containing materials without significantly etching non-targeted objects, which is crucial for semiconductor device fabrication, enabling further miniaturization and integration.
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 carbonyl fluoride as an impurity and the concentration of carbonyl 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.