Low-Temperature Silicon Etching With Metal-Impurity Control
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Solution Overview
Problem
Low-temperature etching methods in semiconductor manufacturing are prone to generating particles, which can short-circuit wiring lines and reduce productivity, while high-temperature methods have insufficient side etching rates.
Innovation Solution
An etching method that maintains a temperature of 0°C or less, using an etching gas with specific metal impurity concentrations and compounds containing fluorine, hydrogen, or oxygen atoms to selectively etch silicon-containing layers without generating particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a low-temperature etching method is used to maintain low side etching rate, then side etching is reduced, but particle generation increases
Solution Approach 1:
The invention changes the chemical composition parameters of the etching gas by strictly controlling metal impurity concentrations (total concentration of all metal types at 4000 ppb by mass or less) and using specific etching compounds containing fluorine, hydrogen, and oxygen atoms. This parameter optimization allows low-temperature etching to proceed with minimal particle generation while maintaining low side etching rates
Solution Approach 2:
The invention creates a highly purified inert etching environment by removing metal impurities from the etching gas. This clean atmosphere prevents unwanted chemical reactions and particle formation during low-temperature etching, enabling both low side etching and minimal particle generation
2Object-generated harmful factors
If a high-temperature etching method is used to reduce particle generation, then particle generation is reduced, but side etching rate increases
Solution Approach 1:
The invention changes the temperature parameter from high to low (0°C or less) while compensating by optimizing gas composition parameters. This allows achieving low particle generation through purified gas chemistry rather than relying on high temperature, thereby maintaining low side etching rates
3Productivity
If metal impurities are present in etching gas, then etching process can proceed, but particle generation increases
Solution Approach 1:
The invention optimizes the metal impurity concentration parameter to 4000 ppb by mass or less. This controlled level of metal impurities allows the etching process to proceed efficiently while preventing excessive particle generation that would occur at higher impurity levels
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 particle generation, maintaining a low side etching rate and enhancing semiconductor element productivity by ensuring high etching selectivity and minimizing defects.
Implementation Method 1
bringing an etching gas containing an etching compound into contact with the member to be etched, and etching the etching object, the etching compound being a compound having at least one type of atom among a fluorine atom, a hydrogen atom, and an oxygen atom in the molecule
Implementation Method 2
setting the temperature of a member to be etched having an etching object containing silicon to 0° C. or less
Data Source
AI summary
An etching method including an etching step of setting the temperature of a member to be etched having an etching object containing silicon to 0° C. or less, bringing an etching gas containing an etching compound into contact with the member to be etched, and etching the etching object, the etching compound being a compound having at least one type of atom among a fluorine atom, a hydrogen atom, and an oxygen atom in the molecule. The etching gas contains or does not contain metal impurities having at least one type of metal. When the etching gas contains the metal impurities, the total concentration of all types of the contained metals is 4000 ppb by mass or less.