In this study, we changed the input parameters (gas mixing ratio, RF power, DC bias voltage, and process pressure),and then monitored the effect on TiN etch rate and selectivity with SiO2. When the RF power, DC-bias voltage, andprocess pressure were fixed at 700 W, - 150 V, and 15 mTorr, the etch rate of TiN increased with increasing CF4 contentfrom 0 to 20 % in CF4/Ar plasma. The TiN etch rate reached maximum at 20% CF4 addition. As RF power, DC biasvoltage, and process pressure increased, all ranges of etch rates for TiN thin films showed increasing trends. Theanalysis of x-ray photoelectron spectroscopy (XPS) was carried out to investigate the chemical reactions betweenthe surfaces of TiN and etch species. Based on experimental data, ion-assisted chemical etching was proposed as themain etch mechanism for TiN thin films in CF4/Ar plasma
The etching characteristics of indium zinc oxide (IZO) in Cl 2 /Ar plasma were investigated, including the etch rate and selectivity of IZO. The IZO etch rate showed non-monotonic behavior with increasing Cl 2 fraction in the Cl 2 /Ar plasma, and with increasing source power, bias power, and process pressure. In the Cl 2 /Ar (75:25%) gas mixture, a maximum IZO etch rate of 87.6 nm/min and etch selectivity of 1.09 for IZO to SiO 2 were obtained. Owing to the relatively low volatility of the by-products formation, ion bombardment was required, in addition to physical sputtering, to obtain high IZO etch rates. The chemical state of the etched surfaces was investigated with X-ray photoelectron spectroscopy. These data suggested that the IZO etch mechanism was ion-enhanced chemical etching.
c A novel method for systematic variation of chemical selectivity is introduced using mixed-ligand gold nanoparticles.We have shown that altering the composition of ligand molecules attached on the nanoparticle surface affected interaction of the nanoparticle sensors with the analyte vapors. A gold nanoparticle hnctionalized with 4-methylbenzenethiol (4-MBT, -SC6H4CH3) was synthesized and used to produce a series of mixed-ligand nanoparticles of 4-MBT and 4-mercatophenol (4-MP, -SC6H40H) with varying ligand composition.High resolution transmission microscopy ( H E M ) analysis of the nanoparticles confirmed that the ligand-exchange reaction to produce binary-ligand nanoparticles did not affect the size of the resulting nanoparticle diameter (-2.3 nm). Thermal gravimetric analysis (TGA) revealed that the amount organic ligand comprising the nanoparticles ranged from 10.4 to 11.3 weight % of the mixed ligand nanoparticles. Especially the two-step mode in weight loss observed in the binary-ligand particles was correlated with the ligand composition. The compositional variation of the ligands in the nanoparticles was well reflected on the selectivity variation as was confirmed by diversified amplitude and response time in the signals. Fairly impressive signal reproducibility was observed at least for ethanol vapor. At least 10 ppm detection limit was observed toward ethanol. S3 showed reasonable linearity ranging from 10 ppm to 100 ppm of ethanol.
In this study, the plasma etching of the TaN thin film with CH4/BCl3/Ar gas chemistries was investigated. The etch rate of the TaN thin film and the etch selectivity of TaN to SiO2 was studied as a function of the process parameters, including the amount of CH4. X-ray photoelectron spectroscopy (XPS) and Field-emission scanning electron microscopy (FE-SEM) was used to investigate the chemical states of the surface of the TaN thin film.
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