Two-dimensional modelling of - radio-frequency discharges for a-Si:H deposition

Abstract

A two-dimensional numerical code, including three fluid modules to account for the description of electrical, thermal and chemical phenomena, has been developed for the modelling of hydrogenated amorphous silicon deposition from SiH 4 -H 2 radio-frequency glow discharges in a cylindrical PECVD reactor. The results of the model are compared to experimental data, obtained by different diagnostic techniques. The calculated radical densities are compared to those measured by threshold ionization mass spectrometry, at the centre of the substrate; the calculated SiH density profile between the electrodes is compared to those measured by laser-induced fluorescence and the radial distribution of the deposition rate on the substrate is compared to profilometry measurements. Globally, the model correctly predicts the main discharge characteristics for experimental conditions normally used for amorphous silicon deposition in the dust-free regime. The moderate agreement between model and experiment occurring for the hydrogen-dominated condition can be attributed to the simplified surface kinetics adopted in the model.

The effect of discharge chamber geometry on the ignition of low-pressure rf capacitive discharges

“…Similar chambers ͑from the viewpoint of the asymmetric distribution of the vacuum rf field͒ have also been widely used in other studies of rf discharges. [20][21][22][23][24][25][26][27][28] We used the technique proposed by Levitskii 4 to record the rf discharge breakdown curves. In the vicinity of, and to the right of, the breakdown curve minimum, first the gas pressure was fixed and then the rf voltage increased slowly until breakdown occurred.…”

Rf discharge dissociative mode in NF3and SiH4

“…In contrast to NF 3 used for etching, the second gas we studied, SiH 4 , is widely applied for depositing hydrogenated amorphous and microcrystalline silicon and silicon nitride [21][22][23][24][25][26][27][28][29][30]. It induced the appearance of numerous experimental and theoretical papers devoted to studying the properties of rf discharge in this gas (see, i.e.…”

Electron drift velocity in silane in strong electric fields determined from rf breakdown curves

“…Silane (SiH 4 ) is widely used for depositing hydrogenated amorphous and microcrystalline silicon, SiO 2 and silicon nitride [1][2][3][4][5][6][7][8][9][10]. Therefore a large number of papers are devoted both to experimental studying and to simulating discharge characteristics in SiH 4 (see, e.g., [11][12][13][14][15][16][17]).…”