Effect of surface treatments/coatings and soft bake profile on surface uniformity and adhesion of SU-8 on a glass substrate

Samantha Grist; Jasbir N. Patel; Moeed Haq; Bonnie L. Gray; Bozena Kaminska

doi:10.1117/12.842957

11 February 2010 Effect of surface treatments/coatings and soft bake profile on surface uniformity and adhesion of SU-8 on a glass substrate

Samantha Grist, Jasbir N. Patel, Moeed Haq, Bonnie L. Gray, Bozena Kaminska

Author Affiliations +

Proceedings Volume 7593, Microfluidics, BioMEMS, and Medical Microsystems VIII; 75930F (2010) https://doi.org/10.1117/12.842957
Event: SPIE MOEMS-MEMS, 2010, San Francisco, California, United States

Abstract

We present the effect of surface treatments/coatings and soft bake temperatures aimed at improving adhesion and surface uniformity of SU-8 on glass substrates. While the adhesion strength of SU-8 to metal layers on glass and silicon has been previously investigated, our research examines the influence of additional surface treatments (RCA, Acetone/IPA rinse) and coatings (fresh/one-day-aged Ti, fresh/one-day-aged Cr, SU-8 2005®) on adhesion strength as well as surface uniformity for 100 μm thick SU-8 films. Additionally, we vary the soft bake times and temperatures while keeping all other process parameters constant, to correlate adhesion strength with surface uniformity of SU-8 films for each surface modification. We have found that for all surface treatments/coatings, a soft bake temperature of 65°C for 90 minutes yielded a more uniform SU-8 film (σ = 5.18 μm) as compared to the manufacturer-recommended soft bake temperature of 95°C (σ = 12.66 μm) for 30 minutes. Consequently, a more uniform SU-8 film provided excellent adhesion strength (> 2 MPa, as determined by stress testing using an Instron® microtester) for both metallic seed layers while the adhesion strength of films baked at 95°C was determined to be < 0.5 MPa. This study, for the first time, has been able to quantitatively determine the adhesion strength of SU-8 films on different seed layers deposited on glass substrates, for varying soft bake temperatures.

Citation Download Citation

Samantha Grist, Jasbir N. Patel, Moeed Haq, Bonnie L. Gray, and Bozena Kaminska "Effect of surface treatments/coatings and soft bake profile on surface uniformity and adhesion of SU-8 on a glass substrate", Proc. SPIE 7593, Microfluidics, BioMEMS, and Medical Microsystems VIII, 75930F (11 February 2010); https://doi.org/10.1117/12.842957

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