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High Resolution Physical Characterization of Single Metallic Nanoparticles
Published on: June 28, 2019
Analysis of p-Si macropore etching using FFT-impedance spectroscopy
Emmanuel Ossei-Wusu1, Jürgen Carstensen, Helmut Föll
1Institute for Materials Science, Christian-Albrechts-University of Kiel, Kaiserstrasse 2, Kiel, 24143, Germany. eow@tf.uni-kiel.de.
Nanoscale Research Letters
|June 22, 2012
Summary
Investigating silicon etching, this study reveals hydrofluoric acid (HF) concentration dictates silicon dissolution rate, while water content controls etch selectivity for macropore formation. Lower water content enhances pore quality.
Area of Science:
- Materials Science
- Electrochemistry
- Semiconductor Processing
Background:
- Macropore formation in silicon is crucial for microelectronics and sensors.
- Understanding the etching mechanism requires detailed analysis of chemical and physical parameters.
- Lithographically defined structures enable precise control over pore initiation.
Purpose of the Study:
- To investigate the influence of water and hydrofluoric acid (HF) concentrations on the etch mechanism of silicon macropores.
- To correlate pore morphology with in situ electrochemical measurements.
- To elucidate the role of different etchant components in controlling pore formation.
Main Methods:
- Etching of low-doped p-type silicon using varying hydrofluoric acid (HF) concentrations in organic electrolytes.
- In situ impedance spectra (IS) measurements using Fast Fourier Transform (FFT) technique during etching.
- Analysis of pore morphology and fitting of impedance data to an equivalent circuit model.
Main Results:
- A simple equivalent circuit model effectively describes the impedance spectra.
- HF concentration directly influences the overall silicon dissolution rate.
- Water content determines the selectivity of silicon dissolution at pore tips and walls, enabling macropore etching.
- Reduced water content in HF/organic electrolytes leads to improved pore quality.
Conclusions:
- The study clarifies the distinct roles of HF and water in silicon macropore etching.
- Electrochemical impedance spectroscopy provides valuable insights into the dynamic etching process.
- Optimizing water content in the electrolyte is key to achieving high-quality silicon macropores.
