Effect of Bias Applied to Hot Wires on Generation of Positive and Negative Charges during Silicon Hot-Wire Chemical Vapor Deposition

Abstract

Hot-wire chemical vapor deposition of silicon films has been studied focusing on the generation of electric charge during the process. The currents measured 1.5 cm below the input and output positions, with respect to the DC power supply, of the hot wires at 2000 °C were +4 and −544 nA/cm2, respectively, and those 4.5 cm below the input and output positions were +3 and −64 nA/cm2, respectively. These data imply that both positive and negative charges are generated presumably by surface ionization of gas molecules on the hot wires, but an appreciable fraction of negative charges was attracted to the electric field around the hot wires, which have the input and output potentials of +18 and 0 V, respectively, provided by the DC power supply. The additional biases of +25 and −25 V applied to the hot wires produced +2.38 and −4.86 × 104 nA/cm2, respectively, 1.5 cm below the input position of the hot wires. The absolute value of the current measured under the negative bias is much larger than that under the positive bias. The additional bias on the hot wires significantly affected the amount of charges, which resulted in the change of microstructure, crystallinity, and growth rate of deposited films.

In-SituMeasurements of Charged Nanoparticles Generated During Hot Wire Chemical Vapor Deposition of Silicon Using Particle Beam Mass Spectrometer

“…It is not yet certain whether the charged nanoparticles are mainly involved, partly involved or hardly involved in the deposition of Si films. However, in our previous studies (Kim et al 2006;Lee et al 2008a,b;Park et al 2009Park et al , 2010Hwang and Lee 2010), the film growth rate, crystallinity, and microstructural evolution of Si films were affected by both substrate bias and wire bias during the HWCVD process. Furthermore, the experiments herein show that the deposition rate of Si films was impractically low under conditions where the generation of charged nanoparticles was suppressed and was increased with increasing number concentration of charged Si nanoparticles.…”

“…Based on the fact that the gas phase nuclei are charged, Lee et al (2008b) applied the substrate bias, which resulted in the increase of the growth rate of Si films. In addition, Park et al (2009Park et al ( , 2010 showed that the electric field generated around the hot wires depended markedly on whether the power supply is DC or AC and affected the spatial distribution of charged nanoparticles in the chamber as well as the deposition behavior during HWCVD of Si.…”

Comparison of charge generation from hot wires between AC and DC power supply and its effect on deposition behavior during hot-wire chemical vapor deposition of silicon

“…2. This is opposite to the case for the DC power [29]. Although the current below the input position was more positive than that below the output position for the DC power, the difference was so small compared with that for the AC power that it is not distinguishable in Fig.…”

“…Although the HWCVD reactor is identical to that of the previous report [29], some changes were made in the present experimental set-up. The chamber was a cylindrical stainlesssteel reactor of 20 cm f  15.5 cm.…”

“…Recently it was shown that the electric field around the hot wires heated by the DC power supply interacted with the charged carriers, which affected the film quality and the deposition rate [29]. However, the electric field around the hot wires heated by the AC power would be different from that by the DC power.…”