Effects of Ethylene/Ammonia Mixtures on Thermal Chemical Vapor Deposition Rates and Microstructures of Carbon Films

Abstract

When ethylene/ammonia (C2H4/NH3) mixtures are used to deposit carbon films by thermal chemical vapor deposition (CVD), effects of C2H4/(C2H4+NH3) ratios on the deposition rate and microstructures of carbon films are investigated. Experimental results reveal that the deposition rate of carbon films increases with the C2H4/(C2H4+NH3) ratio, and also, raises with the residence time, deposition temperature, and working pressure. The kinetics of this thermal CVD process is discussed. The deposition rate of carbon films is proportional to the C2H4/(C2H4+NH3) ratio with a power of first order, which is resulted from the adsorption of remaining precursor gas C2H4 on the silica glass plate substrate. Few nitrogen and hydrogen atoms are incorporated into carbon films. The activation energy (=152 kJ/mole) of carbon deposition is related to the activation energy of C2H4 dissociation. The crystallinity, degree of ordering, and nano-crystallite size of carbon films decrease with increasing the C2H4/(C2H4+NH3) ratio, while the fraction of sp3 carbon sites of carbon films increase. Finally, the results of thermal CVD carbon deposition using C2H4/NH3 mixtures are compared with those using CH4/NH3, C2H2/NH3, and C2H4/N2 mixtures

Kinetics of Thermal Chemical Vapor Deposition and Microstructures of Carbon Films Using Propane/Ammonia Mixtures

“…This implies that about sixteen NH 3 molecules will suppress one C 3 H 8 molecule to form the carbon film. Therefore, the relation between the deposition rate of carbon films and the C 3 H 8 /(C 3 H 8 +NH 3 ) ratio can be further expressed by a power function as: [33][34][35]…”

“…The total mass flow rate of C 3 H 8 and NH 3 is associated with the residence time, τ, of the precursor gas stayed in the deposition zone. 19,35 Even though the precursor gas is decomposed in the deposition zone, the relation between the total mass flow rate and residence time can be approximately estimated as follows. Based on the conservation of volume, the average flow velocity, v av , of the precursor gas in the deposition zone can be acquired as 19,35 Here the reactor, the thickness of the silica glass plate, and the width of the silica glass plate, respectively.…”

“…19,35 Even though the precursor gas is decomposed in the deposition zone, the relation between the total mass flow rate and residence time can be approximately estimated as follows. Based on the conservation of volume, the average flow velocity, v av , of the precursor gas in the deposition zone can be acquired as 19,35 Here the reactor, the thickness of the silica glass plate, and the width of the silica glass plate, respectively. Moreover, the volume flow rate • V can be approximately obtained from the ideal gas equation as: 19,35 In this study, the working pressure p is 40 kPa; the gas constant R is 8.31 J/K • mol; the deposition temperature T is 1138 K, and…”

“…Furthermore, the kinetics of the thermal CVD process using a C 3 H 8 /NH 3 mixture is discussed, and the connection between the z E-mail: stshiue@dragon.nchu.edu.tw thermal CVD process and microstructure of smooth laminar carbon films is considered. Finally, the thermal CVD carbon deposition using a C 3 H 8 /NH 3 mixture is compared with those using CH 4 /NH 3 , 33 C 2 H 2 /NH 3 , 34 C 2 H 4 /NH 3 , 35 and C 3 H 8 /N 2 mixtures. 19…”

A molecular-level analysis of gas-phase reactions in chemical vapor deposition of carbon from methane using a detailed kinetic model

“…Usually, hydrocarbons, such as methane [6,7], ethylene [8,9], and propane [10,11], are taken as carbon sources. When heated to the pyrolysis temperature, the hydrocarbons start pyrolysis, forming a wide variety of molecules and radicals and carbon solid.…”