Frequency dependence of photoresist ashing with dielectric barrier discharges in oxygen

Journal Article · Fri May 01 04:00:00 EDT 1998 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.367402· OSTI ID:627889

Falkenstein, Z ^[1]

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1. Los Alamos National Laboratory, Los Alamos, New Mexico87545 (United States)

This article presents results of the frequency dependence on surface etching of a Novolak-type polymer (Shipley, SPR2) on Si wafers using dielectric barrier discharges in oxygen near atmospheric pressures and room temperature. The etching depth of the photoresist is measured by mechanical profilometry as a function of the applied sinusoidal frequency (1{endash}40 kHz) at different oxygen pressures (250{endash}750 mbar) and gap distances (1{endash}20 mm), along with the energy density that is supplied to the sample surface and into the gas volume, respectively. This approach enables one to generate figures of merit for the etching rates, allowing comparison with conventional plasma surface treatments, as etching rate per power density coupled onto the sample surface (nm min{sup {minus}1} W{sup {minus}1} cm{sup 2}), or coupled into the gas volume (nm min{sup {minus}1} W{sup {minus}1} cm{sup 3}). For all gap spacings and gas pressures both power-density specific etch rates increase with increased applied frequencies, and show an optimal gap distance and gas pressure. The surface of the etched photoresist is characterized by scanning electron microscopy, showing decreasing material damage with increasing frequency. The results obtained in this work suggest dielectric barrier discharges at high frequencies ({gt}10{close_quote}s kHz) as an efficient, alternative plasma source for general surface processing, as they can provide nonthermal gas discharges near atmospheric pressures and thereby eliminate the need for costly vacuum systems without major damage of the plasma-treated surface. {copyright} {ital 1998 American Institute of Physics.}

• OSTI ID: 627889
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 10 Vol. 83; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ATMOSPHERIC PRESSURE
ELECTRIC DISCHARGES
ETCHING
FREQUENCY DEPENDENCE
OXYGEN
PLASMA
POLYMERS
SCANNING ELECTRON MICROSCOPY
SILICON
SURFACE TREATMENTS