Silicon Concentration Analysis in Phosphoric Acid Etching
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Solution Overview
Problem
Existing methods cannot accurately determine the concentration of silicon generated during the etching of silicon nitride in phosphoric acid solutions, especially when a silicon compound is added to enhance selectivity between silicon nitride and silicon oxide.
Innovation Solution
A method involving the dilution of the phosphoric acid solution with a solvent, cooling it to a specific temperature range to precipitate silicon compounds generated during etching, and analyzing the precipitate using a particle analyzer or dissolving it with hydrofluoric acid to determine silicon concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a silicon compound is added to phosphoric acid solution to increase selectivity between silicon nitride and silicon oxide, then selectivity is improved, but the ability to accurately determine silicon concentration generated during etching deteriorates
Solution Approach 1:
The patent extracts the silicon compound added for selectivity enhancement from the total silicon measurement by using a masking agent that selectively binds to the added silicon compound, allowing measurement of only the silicon generated during etching
Solution Approach 2:
The patent introduces a masking agent as an intermediary substance that selectively masks or binds to the added silicon compound, enabling differentiation between added silicon and etching-generated silicon in the analysis
2Device complexity
If the concentration of silicon in etching solution is measured using existing methods, then analysis is simplified, but the measurement becomes unreliable when silicon compound is added
Solution Approach 1:
The masking agent serves as an intermediary that selectively interacts with the added silicon compound, allowing existing analysis methods to be used while achieving reliable differentiation between added and generated silicon
Solution Approach 2:
The patent changes the chemical parameters of the solution by adding a masking agent that alters the measurability of different silicon sources, enabling reliable concentration determination through modified measurement conditions
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
This method allows for accurate determination of silicon concentration generated during etching, while also distinguishing between silicon from the added compound and that generated during etching, thereby improving the reliability of selectivity analysis.
Implementation Method 1
cooling the pure phosphoric acid solution to a temperature range of 1° C. to 35° C. so that only a silicon compound that is generated during the process of etching the silicon nitride precipitates
Data Source
AI summary
The present invention relates to a method of determining the concentration of silicon based on the solubility of silicon in a phosphoric acid solution to determine the concentration of silicon generated in the process of etching silicon nitride. The silicon concentration determination method can determine the concentration of only the silicon that is generated during a process of etching silicon nitride using a phosphoric acid solution. The method optically determines the concentration of a silicon compound that is added to increase selectivity.