Effects of dielectric barrier discharges on silicon surfaces: Surface roughness, cleaning, and oxidation

Abstract

Silicon wafers were exposed to a dielectric barrier discharge (DBD) at atmospheric pressure, which was ignited by applying a high voltage (>12 kV peak voltage) to a small gap (d(g)=300 mu m) above the wafer surface in an oxygen process gas atmosphere. The effect of the DBD on H-terminated silicon and native silicon oxide surfaces was investigated in situ and ex situ by means of Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy (XPS). The influence of the treatment on surface roughness was studied by atomic force microscopy. In order to determine the thickness of the newly formed oxide under DBD influence, the method of calculating the oxide thickness from the Si 2p peak ratio in the XPS spectrum, which has so far been described for thermal oxides only, was adopted with x-ray reflectometry calibration samples. Additionally, infrared spectroscopy and spectroscopic ellipsometry were used to verify the XPS measurements. The calculated thickness values can be fitted with the growth law d=d(0) ln[(t /tau)+k], with d being the oxide thickness, grown during DBD exposure time t. Oxide thicknesses of more than 3 nm could be achieved within 350 s DBD exposure time. Our analysis of infrared spectra, XPS, and ellipsometry leads us to conclude that the newly formed oxide is porous with a pore fraction of roughly 10%

A new low-temperature high-aspect-ratio MEMS process using plasma activated wafer bonding

“…The wafer temperature is not changed because of the short duration of the plasma discharges. Also, it has been reported that the wafer roughness is not modified by DBD plasma [34] after prolonged exposures, a result which is consistent with the observations made during this study as will be discussed in the next section.…”

Melanin Layer on Silicon: an Attractive Structure for a Possible Exploitation in Bio‐Polymer Based Metal–Insulator–Silicon Devices

“…Direct melanin layer deposition onto Si substrates has been achieved here by modifying the substrate surface wettability, i.e., by turning the not hydrophilic (almost hydrophobic) Si surface into a super hydrophilic one by a dry procedure. To this end, water‐vapor fed plasma produced by micro‐capillary dielectric barrier discharge (DBD) has been adopted as a dry procedure in an innovative fashion (see Supporting Information) 20. The Si surface wettability modification has been verified by the water contact angle (WCA) technique: a reduction from a WCA of 62° for the initial untreated surface to 3° (super‐hydrophilic) for the water‐plasma‐treated surface has been measured.…”

Or0504–Investigations on the Effect of Dielectric Barrier Discharge (DBD) Treatment as a Preconditioning Method for Low Temperature Silicon Wafer Bonding

“…Oxide thicknesses of 2.0 ± 0.2 nm and 3.2 ± 0.2 nm, respectively, were measured by X‐ray reflectometry (XRR). These samples were used to calibrate thickness measurement with X‐ray photoelectron spectroscopy (XPS) and ellipsometry 4…”

“…Unfortunately, it is attenuated by an oxide film of individual thickness. With the 6P‐method from Seah and Spencer, which we adapted to the special requirements of the DBD oxide, the oxide thickness can be determined very precisely from the Si2p spectrum 4. The thickness can then be used to calculate the nominal value of the elemental silicon peak for normalization purposes.…”