Particle formation in SiOx film deposition by low frequency plasma enhanced chemical vapor deposition

Abstract

Dust particle formation dynamics in the process of SiOx film deposition from a SiH4 and N2O gas mixture by a low frequency plasma enhanced chemical vapor deposition have been investigated using scanning electron microscopy and laser light scattering. The deposited films are confirmed to be SiOx from the measurements of Auger electron spectroscopy, x-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. It is observed by scanning electron microscopy that particles are deposited on Si substrate at the plasma power frequency f=5 kHz and above both with and without substrate heating (400 °C), while no particle is deposited below f=1 kHz. Moreover, the laser light scattering indicates that particles are generated at the plasma power frequency of f=3 kHz and above in the gas phase, and that they are not generated in the gas phase at below f=3 kHz. Properties (the refractive index, resistivity, and Vickers hardness) of the films with particles are inferior to those of the films without particles. This article has revealed experimentally the effect of plasma power frequency on SiOx particle formation and makes a contribution to the explication of the particle formation mechanism. We suggest that high-quality film deposition with the low frequency plasma enhanced chemical vapor deposition method is attained at f=1 kHz or less without substrate heating.

Diagnostics and Kinetic Modeling of a Hollow Cathode N2O Discharge

“…The problems appear mainly because relevant experimental conditions, especially the surface properties of the electrodes and the walls of the respective reactors, can be very different, and their effects on the species attributed in the model to heterogeneous reactions and thus on 2 and O 2 production are difficult to estimate. In fact, as indicated above, NO 2 has not been observed previously in N 2 O discharges.…”

“…To get good quality films with rf discharges, substrate temperatures cannot be lower than 300−400 °C; at colder temperatures particle formation will negatively affect the properties of the deposited film. However, particle formation can be largely avoided, even with room-temperature substrates, by using low-frequency discharges . Since nitrous oxide is usually the major constituent in the PECVD of silicon oxide, the systematic investigation of N 2 O cold plasmas generated in low frequency or even direct current (dc) discharges can be of great help for the understanding of basic processes influencing the properties of SiO 2 thin films.…”

“…However, particle formation can be largely avoided, even with room-temperature substrates, by using low-frequency discharges. 2 Since nitrous oxide is usually the major constituent in the PECVD of silicon oxide, the systematic investigation of N 2 O cold plasmas generated in low frequency or even direct current (dc) discharges can be of great help for the understanding of basic processes influencing the properties of SiO 2 thin films. In addition, nitrous oxide is also used in the deposition of other materials such as SiO x N y , 3 phosphosilicate glass layers, 4 and aluminum oxides.…”

“…2 and O 2 production are difficult to estimate. In fact, as indicated above, NO 2 has not been observed previously in N 2 O discharges.…”

Characterization of Thermal Oxides on 4H-SiC Epitaxial Substrates Using Fourier-Transform Infrared Spectroscopy

“…[13][14][15][16] Many papers have been published reporting FT-IR studies on the chemical bonding structure, properties, interfacial structures, and functions of thin films. [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] However, in the case of oxides on SiC substrates, IR light cannot pass though the substrates because of the strong absorption due to free carriers and SiC bonds in the substrates. Thus, an attenuated total reflection (ATR) technique has been used for thin films on SiC substrates; this is a highly sensitive method for investigating such films.…”