Study of the growth mechanisms of low-pressure chemically vapour deposited silica films

Abstract

We have studied the surface morphology evolution of Si0 2 films grown at 20 nm/min in a low-pressure chemical vapour deposition reactor from SiHi02 mixtures at low (611 K) and high (723 K) temperatures. Films have been deposited for times ranging from 10 min up to 48 hours. It is shown that the SiO, growth at high temperature becomes stable, whereas at low temperature it is unstable (i.e., the surface roughness increases continuously with deposition time). This clear difference is explained on the basis of the different growth mechanisms operating under both experimental conditions. These results are compared with the predictions of the few theoretical works on growth evolution by chemical vapour deposition.

Dynamic Scale Theory for Characterizing Surface Morphology of Layer-by-Layer Films of Poly(o-methoxyaniline)

“…11 The irregularities resulting from the initial random adsorption process are minimized, thus leading to a less rough surface. 11 The values of a for L Ͻ d are comparable to those reported in the literature for other systems 7,11,[21][22][23] , where a lies between 0.7 and 0.9. For L Ͼ d, the surface roughness is determined by the fluctuation in the height of the globules.…”

Influence of Solution Treatment on the Adsorption and Morphology of Poly(o-methoxyaniline) Layer-by-Layer Films

“…This value is consistent with those reported in the literature, falling in the range 0.7 < R < 0.9. 4,[29][30][31][32] R is related to the fractal dimension (DF) by 32 DF ) D -R(t), where D is the dimension of the space associated with the growth. A value of R < 1 is characteristic of a fractal self-affine surface formation, 33 where the fractal dimension can be estimated as DF ) 3 -R. For our films, the fractal dimension is ca.…”

“…In this context, the kinetics of the processes involved in the adsorption of LBL films are still a matter of debate. 4 LBL films resulting from physical adsorption have been classified 5 according to the adsorption mechanisms as follows: (i) LBL films from highly charged, strong polyelectrolytes are molecularly thin with adsorption governed almost entirely by ionic interactions. (ii) For LBL films from partially charged, weak polyelectrolytes, the thickness can vary by 1 order of magnitude, 6 depending on the pH of the polymer solutions.…”

Modelling of silica film growth by chemical vapour deposition : Influence of the interface properties

“…However, for the high temperature set, this unstable behavior is finally dominated by the KPZ regime that causes lateral growth of the surface structures. This regime turns out to be strongly linked to the conformal nature of CVD, which is of great importance in certain industrial applications [17]. The morphological difference between the high and low T films, specifically the difference in the value of the surface roughness, is directly related to the different surface concentration of active sites (mainly Si-H and strained siloxane groups) and the different short-range memory effects for both growth conditions.…”

“…It is straightforward to obtain the value of the exponents 13 and IIz from the AFM data since this merely requires measuring the change with deposition time of cr and ~, which are obtained directly from the AFM images. Regarding the estimation of the value of exponent a, there are several approaches, namely it can be obtained either from the change of (J with the sampling length [15] or from the Power Spectral Density (PSD) of the AFM images [16,17]. It can be shown that the PSD curve of a rough surface, which is a function of wavevector (inverse length) k = IlL, obeys the following relationship: PSD(k) oc k-(20.+2) This expression implies that the a value can be obtained from the slope of the straight regions observed in a logarithmic plot ofPSD versus k. Likewise, the values of 13 and l/z correspond to the slopes of the straight regions of the logarithmic plots of cr and ~ versus time.…”