Decreasing Interface Defect Densities via Silicon Oxide Passivation at Temperatures Below 450 °C

Area of Science:

• Materials Science
• Semiconductor Physics
• Surface Chemistry

Background:

• Defects at silica (SiO)/silicon (Si) interfaces cause significant losses and malfunctions in electronic, photonic, and medical devices.
• Traditional high-temperature treatments (>700 °C) are ineffective for reducing defect densities in many SiO/Si device structures.
• Low-temperature (LT) passivation (<450 °C) of SiO/Si interfaces is crucial for improving device performance and reliability.

Purpose of the Study:

• To investigate the efficacy of an LT ultrahigh-vacuum (UHV) treatment for reducing defect densities at SiO/Si interfaces.
• To explore a scalable LT passivation method compatible with existing state-of-the-art manufacturing processes.
• To understand the underlying mechanism responsible for defect reduction.

Main Methods:

• A combination of wet chemistry, UHV-based heating, and silicon surface preoxidation was employed.
• The LT-UHV treatment was applied to silica/silicon material combinations.
• Characterization of the SiO/Si interface and defect density measurements were performed.

Main Results:

• The LT-UHV treatment successfully decreased defect densities at the SiO/Si interfaces.
• A novel, previously unreported crystalline silicon oxide phase was formed during the controlled oxidation within the LT-UHV process.
• The observed defect density reduction was approximately 50%, correlating with the formation of the crystalline SiO phase.
• Application as a complementary post-treatment reduced detector leakage current by a factor of 2.

Conclusions:

• LT-UHV treatment is a viable and scalable method for passivating SiO/Si interfaces at temperatures below 450 °C.
• The formation of a crystalline SiO phase is key to the observed significant reduction in defect density.
• This LT-UHV approach offers a promising solution for mitigating electrical losses and improving the performance of semiconductor devices.