The role of substrate temperature and bias in the plasma deposition from tetramethylsilane

Amorphous hydrogenated silicon carbide (a-SiC:H) films are produced by remote microwave hydrogen plasma (RHP)CVD using triethylsilane (TrES) as the single-source precursor. The reactivity of particular bonds of the precursor in the activation step is examined using tetraethylsilane as a model compound for the RHP-CVD experiments. The susceptibility of a TrES precursor towards film formation is characterized by determining the yield of RHP-CVD and comparing it with that of the trimethylsilane precursor. The effect of substrate temperature (T s ) on the rate of the RHP-CVD process, chemical composition, and chemical structure of the resulting a-SiC:H films is reported. The substrate temperature dependence of the film growth rate implies that film growth is independent of the temperature and RHP-CVD is a mass transport-limited process. The examination of the a-SiC:H films, performed by means of X-ray photoelectron spectroscopy (XPS), elastic recoil detection analysis (ERDA), and Fourier transform infrared absorption spectroscopy (FTIR), reveals that the increase in the substrate temperature from 30 -C to 400 -C causes the elimination of organic moieties from the film and the formation of a Si-carbidic network structure. On the basis of the results of the structural study, the chemistry involved in film formation is proposed.

Section: Effect Of Thermal Activationmentioning

confidence: 99%

Growth Mechanism and Chemical Structure of Amorphous Hydrogenated Silicon Carbide (a‐SiC:H) Films Formed by Remote Hydrogen Microwave Plasma CVD From a Triethylsilane Precursor: Part 1

Wróbel

Walkiewicz-Pietrzykowska

Ahola

et al. 2009

“…Moreover, due to its molecular structure, it is possible to obtain materials with compositions ranging from silicon carbide to silicon oxide. [11,12] Recently, the preparation of low-k SiO x C y H z thin films by PECVD from TMS mixtures has been reported by some authors. [13] Compared to other precursors, the plasma chemistry of TMS is not completely understood, particularly in oxygen/ TMS mixtures.…”

Section: Introductionmentioning

confidence: 99%

Plasma Characterization of Oxygen‐Tetramethylsilane Mixtures for the Plasma‐Enhanced CVD of SiO_xC_yH_z Thin Films

Yanguas‐Gil

Barranco

Cotrino

et al. 2006

The plasma-enhanced (PE)CVD of SiO x C y H z thin films from O 2 /Ar/tetramethylsilane (TMS) mixtures, in a low-pressure microwave electron cyclotron resonant (ECR) plasma reactor, has been studied. The discharge has been analyzed by mass spectrometry (MS) and optical emission spectroscopy (OES) for varying amounts of oxygen in the gas mixture both in the presence and in the absence of argon. The films obtained have been characterized by Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS). It is found that the electron impact of the TMS molecules and their dissociative ionization play an important role in the deposition process. Si(OH) x (CH 3 ) 3-x species, produced by reactions between the Si(CH 3 ) 4 molecule and Si(CH 3 ) 3 + ion fragments with O and O 2 , have been identified as important reaction intermediates.Such species form in different proportions depending on the O 2 /TMS ratio in the gas mixture. It is proposed that their incorporation onto the surface of the growing films accounts for the wide range of compositions achieved (ranging from SiO 2 to almost Si:C:H) and the high concentration of Si-C bonds experimentally detected in the SiO x C y H z thin films.

“…Concerning the temperature effect, the increase in the Si/C ratio when the temperature is increased from 453 to 853 K has already been discussed by Favia et al [32] They suggested that any thermal activation lowers the content of H atoms and CH x , leading to a larger cross-linking and to an increase in the Si/C ratio. Concerning the ion bombardment effect, Si/C decreases inversely with the maximum ion energy.…”

Section: Discussionmentioning

confidence: 86%

Electrical Measurements and Optical Emission Spectroscopy of Silicon–Carbon Alloys Grown by PACVD: Correlation with Film Microstructure

Thomas¹,

Tomasella

Badie

et al. 2003

Hard hydrogen-containing silicon±carbon-based films were grown at medium temperatures in the range 453±853 K in a plasma-assisted (PA) CVD device using tetramethylsilane (TMS) as the precursor. TMS plasma chemistry is not clearly understood so, in order to gain a better understanding of this process, both electrical measurements, to estimate ion energy and flux, and optical emission spectroscopy (OES), to identify chemical species occurring in the gas near the film surface, have been used to establish correlations between characteristics of the discharge and the films. In this process, an increase in the energy of the ions tends to lower the silicon to carbon atomic ratio (Si/C) whatever the temperature. Since this is the opposite to what might be expected, it follows that the ion bombardment is a key factor. The Si/C variations are related to the behavior of gaseous emitting species near the plasma sheath close to an a-SiC/H biased surface set in non-reactive (pure argon, argon/H 2 ), then reactive (argon/TMS) plasmas. OES reveals that only a few species (Ar, Ar + , H, and Si + ) are emitting. Their corresponding lines are strongly broadened by the Doppler effect function of the applied bias voltage and plasma nature. The Si + line exhibits two energy populations, fast and slow. The fast one is related to electron dissociative excitation processes involving ions, whereas the slow Si + population seems to originate from neutral groups extracted from the surface or coming from complex species in the plasma gas. Up to three energy components were identified in the H a line profile. One is typical of both the TMS dissociation and the emission of hydrogen-containing species coming from the bombarded deposit. A comparison between the variations of relative densities of Si + and H, and material data, indicates that the deposit can be etched or sputtered (either congruently or non-congruently) leading, in the maximum ion energy range (120±180 eV), to a drastic modification of the film microstructure. This latter point is analyzed in connection with the coating surface hardness (17 GPa < H < 30 GPa).