Surface Modification of Electroosmotic Silicon Microchannel Using Thermal Dry Oxidation

Area of Science:

• Materials Science
• Microfluidics
• Surface Chemistry

Background:

• Silicon microchannels are crucial for microfluidic devices.
• Surface properties significantly impact electroosmotic flow (EOF).
• Existing fabrication methods may have limitations in achieving desired surface characteristics and dimensions.

Purpose of the Study:

• To present a simple fabrication method for surface modification of silicon microchannels.
• To enhance surface quality for electroosmotic fluid transport.
• To reduce microchannel width using thermal dry oxidation.

Main Methods:

• Fabrication of silicon microchannels using plasma etching.
• Surface modification via thermal dry oxidation to form a silicon dioxide (SiO₂) layer.
• Analysis of SiO₂ layer properties and surface quality using Scanning Electron Microscopy (SEM) and a surface profiler.

Main Results:

• Maximum oxidation growth rate observed in the first 4 hours, decreasing over time.
• Reduced surface roughness with increased process temperature and oxide thickness.
• Improvement in the scallop effect on channel walls due to the oxide layer.
• Achieved an approximate 40% reduction in channel width post-oxidation.

Conclusions:

• Thermal dry oxidation is an effective method for silicon microchannel surface modification.
• The process improves surface quality and enables precise width reduction.
• This technique is suitable for fabricating uniform, high-aspect-ratio sub-micro and nanochannels for electroosmotic ion manipulation in biomedical samples.