Subscript textReactive ion etching of barium strontium titanate (BST) thin films using an SF6/Ar plasma has been studied. BST surfaces before and after etching were analyzed by X-ray photoelectron spectroscopy to investigate the reaction ion etching mechanism, and chemical reactions had occurred between the F plasma and the Ba, Sr and Ti metal species. Fluorides of these metals were formed and some remained on the surface during the etching process. Ti can be removed completely by chemical reaction because the TiF4by-product is volatile. Minor quantities of Ti-F could still be detected by narrow scan X-ray photoelectron spectra, which was thought to be present in metal-oxy-fluoride(Metal-O-F). These species were investigated from O1sspectra, and a fluoride-rich surface was formed during etching because the high boiling point BaF2and SrF2residues are hard to remove. The etching rate was limited to 14.28nm/min. A 1-minute Ar/10 plasma physical sputtering was carried out for every 4 minutes of surface etching, which effectively removed remaining surface residue. Sequential chemical reaction and sputtered etching is an effective etching method for BST films.
The authors investigated the effects of annealing in Ar atmosphere at different temperatures (350 °C, 600 °C, and 900 °C) on the thermally oxidized SiO2/4H-SiC interface. A strong correlation between C-related clusters reduction and SiO2/SiC interfacial improvement was observed. The C-related clusters, which were characterized by field-emission scanning electron microscopy, and energy-dispersive spectrometry, can be significantly reduced after annealing at moderate temperature (600 °C). This sample annealed at 600 °C exhibited the best interfacial quality of SiO2/SiC from capacitance–voltage measurement. Based on the studies, improvements in the quality of the SiO2/SiC interface after annealing at 600 °C may be explained by the reduction of C-related clusters during annealing.
Dry etching of Pt/Ti film was carried out using Cl2/Ar plasmas in an inductively coupled plasma (ICP) reactor. The influence of the various process parameters, such as RIE power, ICP power and Cl2/Ar gas mixing ratio, on the etch rate and selectivity of photoresist to Pt/Ti film were investigated systematically and optimized. It was revealed that the etch rate and the selectivity strongly depended on the key process parameters. The etch rate was found to increase dramatically with increasing of RIE power and ICP power. But by changing the ratio of Cl2 to the total gas, the maximum etch rate could be obtained at the proper ratio of 20%. The results also indicated too low or too high RIE power and the Cl2 ratio was detrimental to the selectivity. The optimized parameters of Pt/Ti dry etching for high etch rate and low selectivity of photoresist to Pt/Ti were obtained to be pressure: 10mT, RF power: 250W, ICP power: 0W, Cl2: 8sccm (standard cubic centimeters per minute), Ar: 32sccm.
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