Metrology and characterization of SU-8 microstructures using autofluorescence emission

Area of Science:

• Materials Science
• Microfabrication
• Metrology

Background:

• SU-8 photoresist microstructures are vital in biomedical and microfluidic applications.
• Conventional characterization methods like SEM and profilometry are destructive and cannot assess subsurface features.
• There is a need for non-destructive, accurate metrology for SU-8 microstructures.

Purpose of the Study:

• To develop a unique, non-destructive methodology for dimensional characterization of SU-8 microstructures.
• To utilize autofluorescence emission for generating depth profiles and measuring lateral dimensions.
• To establish a low-cost, accurate metrological technique for SU-8 microstructures.

Main Methods:

• Fabrication of SU-8 microstructures.
• Measurement of autofluorescence emission intensities from SU-8 microstructures.
• Correlation of autofluorescence intensities with microstructure dimensions (thickness, lateral) determined by SEM.
• Application of the established correlation for non-destructive characterization and depth profiling.

Main Results:

• A quantitative relationship was established between autofluorescence emission intensities and SU-8 microstructure thicknesses.
• The methodology accurately characterized both surface and hidden subsurface features, including microchannels.
• Depth profiles were generated with high accuracy, validated by comparison with SEM measurements.
• Lateral dimensions were also successfully measured.

Conclusions:

• Autofluorescence emission provides a feasible and accurate non-destructive metrological technique for SU-8 microstructures.
• This method enables low-cost characterization of both surface and subsurface features.
• The developed technique offers a valuable alternative to destructive metrology for SU-8 based devices.