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Doped or Quantum-Dot Layers as In Situ Etch-Stop Indicators for III/V Semiconductor Reactive Ion Etching (RIE) Using
Guilherme Sombrio1, Emerson Oliveira1, Johannes Strassner1
1Research Group Integrated Optoelectronics and Microoptics (IOE), Physics Department, Technische Universität Kaiserslautern (TUK), P.O. Box 3049, D-67653 Kaiserslautern, Germany.
Micromachines
|May 5, 2021
Summary
Reflectance anisotropy spectroscopy (RAS) precisely monitors semiconductor etching in real-time. New methods achieve reliable etch-depth resolution using indicator layers, enabling precise termination of etching processes.
Area of Science:
- Materials Science
- Semiconductor Physics
- Optical Spectroscopy
Background:
- Reflectance anisotropy spectroscopy (RAS) is established for monitoring epitaxial growth.
- Previous work demonstrated RAS for in situ, real-time monitoring of III/V semiconductor reactive ion etching.
- High in situ etch-depth resolution (±0.8 nm) was achieved using optical Fabry-Perot oscillations and a Vernier scale protocol.
Purpose of the Study:
- To demonstrate reliable in situ etch-depth resolution without a Vernier scale protocol.
- To investigate the use of doped layers or quantum dot layers as etch-stop indicators.
- To enable precise termination of reactive ion etching processes.
Main Methods:
- Utilized Reflectance Anisotropy Spectroscopy (RAS) for in situ monitoring.
- Employed thin doped layers or sharp interfaces between differently doped layers/quantum dot layers as etch-stop indicators.
- Analyzed spectral changes in RAS corresponding to the etching of indicator layers.
Main Results:
- Achieved reliable etch-depth resolutions of approximately ±5.6 nm without a Vernier scale.
- Demonstrated that RAS spectra show distinct changes even for very thin indicator layers.
- Confirmed that these spectral changes allow for precise termination of the etch run at typical etch rates (0.7–1.3 nm/s).
Conclusions:
- Thin doped layers or quantum dot layers serve as effective etch-stop indicators for RAS monitoring.
- RAS provides a reliable method for precise etch termination in semiconductor fabrication.
- This technique enhances control over critical dimensions in III/V semiconductor processing.
