Layer Transfer from Chemically Etched 150 mm Porous Si Substrates

Area of Science:

• Materials Science
• Semiconductor Manufacturing
• Chemical Engineering

Background:

• Porous silicon (Si) is a key material for silicon layer transfer.
• Current methods rely on electrochemical etching for surface conditioning.
• A novel chemical etching approach is needed to advance Si layer transfer.

Purpose of the Study:

• To demonstrate the first successful layer transfer of epitaxially grown monocrystalline Si films.
• To develop and characterize a novel chemical stain etching process for porous Si substrates.
• To adapt epitaxy processes for chemically etched porous Si.

Main Methods:

• Utilizing a purely chemical stain etching process with an aqueous HF-rich HF/HNO₃ solution.
• Developing a 150 mm diameter porous Si substrate.
• Adapting epitaxy processes to account for the unique porosity profile of stain-etched substrates.

Main Results:

• Successful layer transfer of an epitaxially grown monocrystalline Si film to a glass carrier.
• Demonstrated a chemical stain etching process as an alternative to electrochemical etching.
• Characterized porosity profiles, showing higher porosity at the surface and lower at the bulk interface.

Conclusions:

• Chemical stain etching is a viable method for porous Si substrate preparation for layer transfer.
• The developed method enables the production of high-quality monocrystalline Si films on glass.
• This technique opens new possibilities for cost-effective semiconductor manufacturing and device fabrication.