The structure and composition of fluorocarbon materials deposited in pulsed and continuous wave (CW) hexafluoropropylene oxide (HFPO) plasmas were investigated. Results indicate substantial dependence on substrate position relative to the rf coil. When the substrate was placed 8 cm downstream from the rf coil (25 W CW), highly amorphous, cross-linked films were obtained. In contrast, materials deposited 28 cm downstream from the rf coil contained less cross-linked moieties and a higher degree of order. Angle-resolved X-ray photoelectron spectroscopy (XPS) C 1s analysis showed that the 28 cm materials contain up to ∼80% CF 2 and CF 3 surface-enriched layers. Static secondary ion mass spectroscopy (SIMS) data revealed that these fluorocarbon materials are composed of long CF 2 chains. Near edge X-ray absorption fine structure (NEXAFS) analysis showed that the CF 2 chains were oriented perpendicular to the substrate surface for the films deposited at 28 cm downstream, while the films obtained 8 cm downstream do not exhibit any particular orientation. The compositions of materials deposited in pulsed HFPO systems have rf power and distance dependencies similar to those observed in the CW plasmas.

Using the imaging of radicals interacting with surfaces (IRIS) technique, the scattering of NH 2 on a variety of substrates has been measured during NH 3 , NH 3 /H 2 , and NH 3 /SiH 4 plasma processing. In most cases, NH 2 surface scattering was greater than unity for 300 K substrates, suggesting that NH 2 is produced through surface reactions. Removal of the charged species from the plasma molecular beam results in a significant decrease in scattered NH 2 signal. We have also measured velocity distributions and translational temperatures for NH 2 radicals scattering from 300 K substrates. Monte Carlo simulation methods were used to model spatially and temporally resolved profiles of scattered molecules. The model assumes an initial Gaussian distribution for radicals across the laser beam and calculates time-dependent changes in the profiles using Maxwell-Boltzmann distributions. For NH 2 radicals scattering from a 300 K Si substrate, the translational temperature, Θ Tsc , is 400 ( 30 K, significantly higher than the substrate temperature. Removal of the charged species from the plasma molecular beam results in a decrease in translational temperature for scattered NH 2 molecules, Θ Tsc ) 300 ( 30 K. This suggests ions are important in surface production of NH 2 and in the translational temperature of the scattered radicals.

The interactions of NH2 radicals with different substrate materials during NH3 plasma processing were investigated using the imaging of radicals interacting with surfaces (IRIS) technique. NH2 scatter coefficients, S, were obtained as a function of applied rf power for polyimide, poly(tetrafluoroethylene) (PTFE), platinum, copper, and silicon substrates. For most experimental conditions, S ≥ 1, indicating that NH2 surface generation occurs at the plasma-substrate interface. Information on energy transfer between NH2 and the different substrates during processing was gleaned from measurements of the translational temperature for scattered NH2 molecules, ϑTsc, as a function of applied rf powers. NH2 radicals scattered from Pt, Cu, and Si substrates have very little dependence of ϑTsc on rf power, whereas the two polymeric materials demonstrate a nearly linear increase in ϑTsc with applied rf power. The change was most dramatic for polyimide substrates, where ϑTsc increased by ∼120 K between 50 and 150 W. Scattering coefficients and ϑTsc values measured using a molecular beam without ions indicate that charged species serve to increase both the kinetic energy and the amount of scattered NH2 radicals. Mechanistic implications for NH3 plasma processing are drawn from both the scatter coefficient results and the energy transfer data.

Interligand electron transfer kinetics have been measured in OsII(bipyridine)3 following photoexcitation to the metal-to-ligand charge-transfer state. The measurements are made in room temperature solutions of acetonitrile, ethylene glycol, and glycerol, using time-resolved absorption polarization spectroscopy. The experimental results are strongly dependent on excitation wavelength and are in agreement with the results of reaction/diffusion model calculations. In the calculations, motion along the solvent polarization coordinate is treated as diffusion, and reaction is treated in the nonadiabatic (acetonitrile) or adiabatic (ethylene glycol) limits. The adjustable parameters of the model are the interligand electronic coupling and the solvent polarization barrier height, which are taken to be 15 and 500 cm-1, respectively. The relaxation processes giving rise to the observed kinetic components are discussed.

Studies of fluorocarbon film deposition and its correlation with etched trench sidewall angle by employing a gap structure using C 4 F 8 ∕ Ar and C F 4 ∕ H 2 based capacitively coupled plasmas Comparison of plasma chemistries and structure-property relationships of fluorocarbon films deposited from octafluorocyclobutane and pentafluoroethane monomers Materials deposited in continuous wave ͑cw͒ and pulsed low-pressure octafluoropropane (C 3 F 8 ) and octafluorocyclobutane (c-C 4 F 8 ) plasmas were characterized using Fourier transform infrared spectroscopy ͑FTIR͒, x-ray photoelectron spectroscopy, static contact angle measurements, spectroscopic ellipsometry, and scanning electron microscopy ͑SEM͒. Fluorocarbon ͑FC͒ materials deposited in pulsed plasmas were less crosslinked than those deposited in cw plasmas with equivalent input powers. Within each system, higher F/C ratio materials were deposited by lowering the plasma input power/duty cycle. Using downstream depositions had a similar effect on film composition, but also resulted in decreased deposition rates. SEM analysis showed that decreases in the flexibility of the fluorocarbon films were correlated with increases in the percent of crosslinking. Additionally, the smoothness of the film surfaces suggests that polymerization processes occur on the substrate surface. Overall, films deposited in C 4 F 8 plasmas were more crosslinked and less flexible than those deposited in C 3 F 8 plasmas under the same conditions. The composition of the deposited FC films is correlated to the nature and relative concentrations of nascent ions previously measured in these plasma systems using plasma ion mass spectrometry.