Mechanics of hydrogenated amorphous carbon deposits from electron-beam-induced deposition of a paraffin precursor J. Appl. Phys. 98, 014905 (2005); 10.1063/1.1940138 Effects of thermal annealing on the structural, mechanical, and tribological properties of hard fluorinated carbon films deposited by plasma enhanced chemical vapor deposition In this work, antiwear nanoimprint templates were made by depositing and patterning diamondlike carbon ͑DLC͒ films on Si and quartz. A capacitively coupled plasma enhanced chemical vapor deposition ͑PECVD͒ system was configured to deposit 100 nm-1 m thick DLC films on Si and quartz substrates. These films were characterized with Raman spectroscopy, electron energy loss spectroscopy, atomic force microscopy, nanoindentation, contact angle measurements, and optical transmission measurements. The rf power and pressure of the PECVD process were varied to obtain uniform coating of DLC films with smooth surface ͑ϳ0.2 nm rms͒, low surface energy ͑ϳ40 mJ/ m 2 ͒, and high hardness ͑ϳ22 GPa͒. The resulting films' wear resistance is more than three times better than quartz. The DLC films were patterned by nanoimprint lithography using polymethylmethacrylate ͑PMMA͒ followed by CF 4 plasma etch. Thermal nanoimprint tests with DLC templates were performed in PMMA. Atomic force microscopy measurements indicated excellent pattern-transfer fidelity and template-polymer separation.
The effect of wall temperature, from 50to200°C, on gas phase chemistry and substrate etching rates has been studied in inductively coupled CF4 plasma under two distinctive initial wall conditions, namely “clean” and “seasoned.” During plasma etching, we found that the gas phase chemistry exhibits a weak dependence on the initial wall cleanliness when the wall is either cold (50°C) or hot (200°C). In the mid-temperature range, the wall cleanliness can strongly affect gas phase chemistry. The study of temperature dependence of the fluorocarbon film deposition on the substrate indicates that ion-assisted incorporation, direct ion incorporation and ion-assisted desorption are the major factors determining film growth and removal. Ion-assisted incorporation and desorption are surface-temperature-dependent, while direct ion incorporation is independent of the surface temperature.
In a typical plasma tool, both etch and deposition occur simultaneously. Extensive experimental measurements are used to help develop a general model of etch and deposition processes. This model employs reaction probabilities, or surface averaged cross sections, to link the measurable surface processes, etch and deposition, to the flux of various species to the surfaces. Because the cross sections are quantum mechanical in nature, this surface rate model should be applicable to many low temperature plasma processing systems. Further, the parameters that might be important in reaction cross sections are known from quantum mechanics, e.g., species, energy, temperature, and impact angle. Such parameters might vary from system to system, causing the wide processing variability observed in plasma tools. Finally the model is used to compare measurements of ion flux, ion energy, and fluorocarbon radical flux to the measured process rates. It is found that the model appears to be consistent with calculations of gain/loss rates for the various radicals present in the discharge as well as measured etch and deposition rates.
This paper examines the complex nature of highly polymerizing fluorocarbon plasmas. An inductively coupled modified GEC reference cell is used to look at process rates on SiO 2 , p-Si and Si 3 N 4 samples using various chamber geometries and gas chemistries. In an attempt to understand the process rates, a simple model based on the sticking and etch yield coefficients of radicals and ions is employed. Development of the model requires knowledge of radical flux, ion flux, ion energy and related process rates. These values are determined using in situ spectroscopic ellipsometry, in situ optical emission spectroscopy, in situ Fourier transform infrared spectroscopy and chuck self-bias measurements. Through the use of a variable electrode gap and changing feed gas chemistry, sticking radical densities are controlled almost independently of ions and etching radical densities. This control allows a partial deconvolution of the process rate equation. Estimated values for the upper bound sticking coefficients of fluorocarbon radicals are made. Additionally, values are reported for ion sticking coefficients and the fluorine etch yield coefficient. These values are then used in a basic low ion energy model to compare with experimental process rates.
Plasma-wall interactions in fluorocarbon based feedgas chemistries, namely CF4, are examined in a standard inductively coupled Gaseous Electronics Conference reference cell using in situ Fourier-transform infrared spectroscopy and microwave interferometry. Measurements show the dissociation of the CF4 feedgas into radical CFx species, as has been observed elsewhere [M. J. Goeckner and R. A. Breun, J. Vac. Sci. Technol. A 11, 3 (1993)], and qualitatively reveal a decrease in plasma-wall interactions as wall temperature is increased. Experimental results such as plasma density, 1011 cm−3, and CF4 density 1013 cm−3, are further compared to results from the hybrid plasma equipment model [R. Kinder and M. J. Kushner, J. Vac. Sci. Technol. A 19, 76 (2001)] to better elucidate the influence of wall temperature on plasma exposed surfaces and sticking coefficients. Last, CF4 vibrational temperatures were also measured, revealing that the line-averaged vibrational temperature remains at a constant 40–60 K above the chamber wall temperature while the vibrational temperature in the center of the discharge is significantly higher. Moreover, the vibrational temperatures are further compared to results from a global thermal model and are in good agreement.
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