Low-Temperature Silicon Etching With Impurity Condensation Control
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Solution Overview
Problem
Low-temperature etching methods face challenges with low etching rates and low etching selectivity, often due to impurity condensation which can lead to etch stop and bowing issues.
Innovation Solution
An etching method is developed where the temperature of the member to be etched is set to 0° C. or less, using an etching gas with high-boiling-point impurities at concentrations of 500 ppm by volume or less, to minimize impurity condensation and enhance etching selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If low-temperature etching method is used, then side etching rate is reduced, but etching rate and etching selectivity become low
Solution Approach 1:
The patent changes the temperature parameter to 0°C or less to reduce side etching, and simultaneously controls the concentration parameter of high-boiling-point impurities to 500 ppm by volume or less. This dual parameter control resolves the contradiction by maintaining low temperature benefits while preventing impurity condensation that would otherwise reduce etching rate and selectivity.
2Manufacturing precision
If low-temperature etching method is used, then side etching rate is reduced, but etching selectivity becomes low
Solution Approach 1:
The patent controls the concentration parameter of high-boiling-point impurities to 500 ppm by volume or less while maintaining temperature at 0°C or less. This prevents impurity condensation that would cause bowing and reduce etching selectivity, thereby resolving the contradiction between reduced side etching and maintained selectivity.
3Productivity
If high-boiling-point impurities are present in etching gas, then etching can proceed, but impurity condensation causes etch stop and bowing
Solution Approach 1:
The patent sets the concentration parameter of high-boiling-point impurities to 500 ppm by volume or less, which is sufficient to maintain etching reactions while preventing condensation at low temperatures. This resolves the contradiction by optimizing the impurity concentration to balance reactivity and condensation prevention.
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 the occurrence of bowing and etch stop, resulting in higher etching rates and selectivity, thereby improving the productivity of semiconductor elements.
Implementation Method 1
bringing an etching gas containing an etching compound into contact with the member to be etched, and etching the etching object
Implementation Method 2
the mixed impurities have had a risk of being condensed in etching, causing a decrease in the etching rate and the etching selectivity
Implementation Method 3
a high-temperature etching method, in which etching is performed at temperatures equal to or more than normal temperature
Data Source
AI summary
A low-temperature 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 gas contains or does not contain high-boiling-point impurities, the high-boiling-point impurities being compounds having at least one type of atom among a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a hydrogen atom, and an oxygen atom in the molecule and having a boiling point of 20° C. or more under a pressure of 101 kPa, and, when the etching gas contains the high-boiling-point impurities, the total concentration of all types of the contained high-boiling-point impurities is 500 ppm by volume or less.