Carbon Hole Etching Gas for Vertical Sidewalls and Low Bowing
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Solution Overview
Problem
The existing dry etching processes face challenges in achieving vertical processability and minimizing bowing in the side wall surfaces of holes during the formation of semiconductor devices, particularly in carbon materials, due to the formation of a polymer film that hinders etching.
Innovation Solution
An etching method using fluoro-dithiethane (CxFyS2) as the etching compound, with controlled metal impurity concentrations and specific gas mixtures, to suppress side wall etching and promote vertical etching of carbon materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a polymer film is formed on the side wall surface of the hole to suppress side wall etching, then bowing is reduced, but the etching rate and vertical processability are hindered
Solution Approach 1:
The invention changes the chemical composition parameters of the etching gas by introducing fluoro-dithiethane (C2F4S2) as a key component. This specific compound generates a polymer film with different properties that provides side wall protection while maintaining etching performance. The gas composition is controlled within specific ranges (C2F4S2: 1-50 sccm, total flow: 50-500 sccm) to optimize the balance between protection and etching rate.
Solution Approach 2:
The invention uses a composite etching gas system combining fluoro-dithiethane (C2F4S2) with other gases such as CF4, CHF3, and C4F8. This composite gas mixture creates a synergistic effect where the polymer film formed has enhanced protective properties while the etching process maintains high vertical processability and etching rate. The composite approach allows simultaneous achievement of side wall protection and efficient etching.
2Shape
If conventional etching gas is used, then the etching process is simple, but bowing occurs in the side wall surface of the hole
Solution Approach 1:
The invention modifies the etching gas parameters by incorporating fluoro-dithiethane (C2F4S2) at controlled concentrations (1-50 sccm). This parameter change transforms the gas chemistry to produce a polymer film that prevents bowing. The specific concentration range and composition ratios are optimized to achieve side wall protection without excessive complexity in the gas delivery system.
3Shape
If the polymer film is made more resistant to etching to better protect the side wall, then bowing is suppressed, but the etching selectivity and vertical processability deteriorate
Solution Approach 1:
The invention optimizes the polymer film properties by controlling the fluoro-dithiethane concentration and gas flow ratios. The C2F4S2 concentration is maintained within 1-50 sccm to produce a polymer film with appropriate protection level that does not overly resist etching. This parameter control ensures the film provides sufficient side wall protection while allowing the etching process to maintain excellent vertical processability and selectivity.
Solution Approach 2:
The invention employs periodic alternation between etching phases and polymer deposition phases. During etching, the polymer film protects the side walls; during deposition phases, the film is replenished or adjusted. This periodic action allows the system to maintain optimal protection levels without permanently compromising etching performance, achieving both side wall protection and vertical processability.
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 effectively reduces bowing in the side wall surfaces of holes, enabling precise formation of semiconductor elements with improved vertical processability and accuracy.
Implementation Method 1
plasm etching the etching object, and forming a hole in the etching object
Implementation Method 2
an etching step of bringing an etching gas containing an etching compound into contact with a member to be etched
Implementation Method 3
a polymer resistant to etching is generated from the etching compound, and a protective film containing the polymer is formed on the side wall surface of the hole
Data Source
AI summary
An etching method includes: an etching step of bringing an etching gas containing an etching compound into contact with a member to be etched (400) having an etching object (carbon material) subject to etching by the etching gas, plasm etching the etching object, and forming a hole in the etching object. The etching compound is fluoro-dithiethane represented by Chemical Formula CxFyS2, wherein, in Chemical Formula, x is 2 or more and 6 or less and y is 4 or more and 12 or less. The etching gas contains or does not contain at least one type among sodium, magnesium, aluminum, potassium, calcium, chromium, manganese, iron, cobalt, nickel, copper, and molybdenum, and, when the at least one type of metal is contained, the total concentration of all types of the metals contained is 100 ppb by mass or less.