High-resolution electron microscopy and scanning tunneling microscopy of native oxides on silicon

Area of Science:

• Materials Science
• Surface Science
• Semiconductor Physics

Background:

• The native oxide layer on silicon surfaces is crucial for semiconductor device fabrication.
• Understanding the structure and formation of this oxide is essential for optimizing silicon processing.
• Surface preparation methods significantly influence the properties of the native oxide.

Purpose of the Study:

• To investigate the structure of the native oxide on silicon surfaces at room temperature.
• To compare the effects of different silicon wafer cleaning procedures on oxide morphology.
• To evaluate how oxide structure impacts further processing on silicon substrates.

Main Methods:

• Utilized high-resolution transmission electron microscopy (HRTEM) for detailed structural analysis.
• Employed scanning tunneling microscopy (STM) to examine surface topography and morphology.
• Combined HRTEM and STM to obtain complementary structural and morphological data.

Main Results:

• Identified differences in native oxide morphology based on cleaning procedures.
• Found that an etch ending with hydrofluoric acid (HF) resulted in a thinner oxide layer.
• Observed a lower interface step density with the HF etch compared to sulfuric peroxide treatment.

Conclusions:

• Cleaning procedures critically influence the native oxide's morphology and interface properties.
• The HF etch offers advantages for creating thinner, smoother silicon oxide interfaces.
• Complementary HRTEM and STM provide comprehensive insights into silicon native oxide structures.