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Title: Effect of dual frequency on the plasma characteristics in an internal linear inductively coupled plasma source

Abstract

An internal-type linear inductive antenna, referred to as a ''double comb-type antenna,'' was used as a large area plasma source with a substrate size of 880x660 mm{sup 2} (fourth generation glass size). The effects of the dual frequency (2 and 13.56 MHz) radio frequency (rf) power to the antenna as well as the power ratio on the plasma characteristics were investigated. High-density plasma on the order of 1.7x10{sup 11} cm{sup -3} could be obtained with a dual frequency power of 5 kW (13.56 MHz) and 1 kW (2 MHz) at a pressure of 15 mTorr Ar. This plasma density was lower than that obtained for the double comb-type antenna using a single frequency alone (5 kW, 13.56 MHz). However, the use of the dual frequency with a rf power ratio of approximately 1(2 MHz):5(13.56 MHz) showed better plasma uniformity than that obtained using the single frequency. Plasma uniformity of 6.1% could be obtained over the substrate area. Simulations using FL2L code confirmed the improvement in the plasma uniformity using the dual frequency to the double comb-type antenna.

Authors:
; ; ; ;  [1];  [2]
  1. Department of Materials Science and Engineering, Sungkyunkwan University, Suwon, Kyunggi-do 440-746 (Korea, Republic of)
  2. (Korea, Republic of)
Publication Date:
OSTI Identifier:
20880179
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 89; Journal Issue: 25; Other Information: DOI: 10.1063/1.2405417; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ANTENNAS; ARGON; GLASS; MHZ RANGE 01-100; PLASMA; PLASMA DENSITY; PLASMA SIMULATION; RADIOWAVE RADIATION; SUBSTRATES; WALL EFFECTS

Citation Formats

Kim, K. N., Lim, J. H., Yeom, G. Y., Lee, S. H., Lee, J. K., and Department of Electronic and Electrical Engineering, Pohang University of Science and Technology, Pohang 790-784. Effect of dual frequency on the plasma characteristics in an internal linear inductively coupled plasma source. United States: N. p., 2006. Web. doi:10.1063/1.2405417.
Kim, K. N., Lim, J. H., Yeom, G. Y., Lee, S. H., Lee, J. K., & Department of Electronic and Electrical Engineering, Pohang University of Science and Technology, Pohang 790-784. Effect of dual frequency on the plasma characteristics in an internal linear inductively coupled plasma source. United States. doi:10.1063/1.2405417.
Kim, K. N., Lim, J. H., Yeom, G. Y., Lee, S. H., Lee, J. K., and Department of Electronic and Electrical Engineering, Pohang University of Science and Technology, Pohang 790-784. Mon . "Effect of dual frequency on the plasma characteristics in an internal linear inductively coupled plasma source". United States. doi:10.1063/1.2405417.
@article{osti_20880179,
title = {Effect of dual frequency on the plasma characteristics in an internal linear inductively coupled plasma source},
author = {Kim, K. N. and Lim, J. H. and Yeom, G. Y. and Lee, S. H. and Lee, J. K. and Department of Electronic and Electrical Engineering, Pohang University of Science and Technology, Pohang 790-784},
abstractNote = {An internal-type linear inductive antenna, referred to as a ''double comb-type antenna,'' was used as a large area plasma source with a substrate size of 880x660 mm{sup 2} (fourth generation glass size). The effects of the dual frequency (2 and 13.56 MHz) radio frequency (rf) power to the antenna as well as the power ratio on the plasma characteristics were investigated. High-density plasma on the order of 1.7x10{sup 11} cm{sup -3} could be obtained with a dual frequency power of 5 kW (13.56 MHz) and 1 kW (2 MHz) at a pressure of 15 mTorr Ar. This plasma density was lower than that obtained for the double comb-type antenna using a single frequency alone (5 kW, 13.56 MHz). However, the use of the dual frequency with a rf power ratio of approximately 1(2 MHz):5(13.56 MHz) showed better plasma uniformity than that obtained using the single frequency. Plasma uniformity of 6.1% could be obtained over the substrate area. Simulations using FL2L code confirmed the improvement in the plasma uniformity using the dual frequency to the double comb-type antenna.},
doi = {10.1063/1.2405417},
journal = {Applied Physics Letters},
number = 25,
volume = 89,
place = {United States},
year = {Mon Dec 18 00:00:00 EST 2006},
month = {Mon Dec 18 00:00:00 EST 2006}
}
  • This study examined the effect of the antenna capacitance of an inductively coupled plasma (ICP) source, which was varied using an internal linear antenna, on the electrical and plasma characteristics of the ICP source. The inductive coupling at a given rf current increased with decreasing antenna capacitance. This was caused by a decrease in the inner copper diameter of the antenna made from coaxial copper/quartz tubing, which resulted in a higher plasma density and lower plasma potential. By decreasing the diameter of the copper tube from 25 to 10 mm, the plasma density of a plasma source size of 2750x2350more » mm{sup 2} was increased from approximately 8x10{sup 10}/cm{sup 3} to 1.5x10{sup 11}/cm{sup 3} at 15 mTorr Ar and 9 kW of rf power.« less
  • Using a Langmuir probe, time resolved measurements of plasma parameters were carried out in a discharge produced by a pulsed dual frequency inductively coupled plasma source. The discharge was sustained in an argon gas environment at a pressure of 10 mTorr. The low frequency (P{sub 2} {sub MHz}) was pulsed at 1 kHz and a duty ratio of 50%, while high frequency (P{sub 13.56} {sub MHz}) was maintained in the CW mode. All measurements were carried out at the center of the discharge and 20 mm above the substrate. The results show that, at a particular condition (P{sub 2} {sub MHz} = 200more » W and P{sub 13.56} {sub MHz }= 600 W), plasma density increases with time and stabilizes at up to ∼200 μs after the initiation of P{sub 2} {sub MHz} pulse at a plasma density of (2 × 10{sup 17} m{sup −3}) for the remaining duration of pulse “on.” This stabilization time for plasma density increases with increasing P{sub 2} {sub MHz} and becomes ∼300 μs when P{sub 2} {sub MHz} is 600 W; however, the growth rate of plasma density is almost independent of P{sub 2} {sub MHz}. Interestingly, the plasma density sharply increases as the pulse is switched off and reaches a peak value in ∼10 μs, then decreases for the remaining pulse “off-time.” This phenomenon is thought to be due to the sheath modulation during the transition from “pulse on” to “pulse off” and partly due to RF noise during the transition period. The magnitude of peak plasma density in off time increases with increasing P{sub 2} {sub MHz}. The plasma potential and electron temperature decrease as the pulse develops and shows similar behavior to that of the plasma density when the pulse is switched off.« less
  • The variation in plasma uniformity over an extremely large size inductively coupled plasma (ICP) source of 2750x2350 mm{sup 2} was examined. An internal linear-type antenna called ''double comb-type antenna'' was used as the ICP source. A plasma density of {approx}1.4x10{sup 11}/cm{sup 3} could be obtained at 5 mTorr Ar by applying 10 kW rf power to the source at a frequency of 13.56 MHz. An increase in rf power from 1 to 10 kW improved the plasma uniformity over a substrate area of 2300x2000 mm{sup 2} from 18.1% to 11.4%. The improvement in uniformity of the internal ICP source wasmore » attributed to the increase in plasma density near the wall.« less
  • An electron emitting probe in saturated floating potential mode has been used to investigate the temporal evolution of plasma potential and the effect of substrate RF biasing on it for pulsed dual frequency (2 MHz/13.56 MHz) inductively coupled plasma (ICP) source. The low frequency power (P{sub 2MHz}) has been pulsed at 1 KHz and a duty ratio of 50%, while high frequency power (P{sub 13.56MHz}) has been used in continuous mode. The substrate has been biased with a separate bias power at (P{sub 12.56MHz}) Argon has been used as a discharge gas. During the ICP power pulsing, three distinct regionsmore » in a typical plasma potential profile, have been identified as ‘initial overshoot’, pulse ‘on-phase’ and pulse ‘off-phase’. It has been found out that the RF biasing of the substrate significantly modulates the temporal evolution of the plasma potential. During the initial overshoot, plasma potential decreases with increasing RF biasing of the substrate, however it increases with increasing substrate biasing for pulse ‘on-phase’ and ‘off-phase’. An interesting structure in plasma potential profile has also been observed when the substrate bias is applied and its evolution depends upon the magnitude of bias power. The reason of the evolution of this structure may be the ambipolar diffusion of electron and its dependence on bias power.« less
  • In a low-pressure radio-frequency (13.56 MHz), inductively coupled argon plasma generated by a normal cylindrical rf coil, electric field, current density, and absorbed power density is calculated from magnetic field measured with a phase-resolved magnetic probe. The anomalous skin effect (ASE) for the cylindrical rf coil is compared to those previously reported for the planar and re-entrant cylindrical rf coils. Physical reasons for our observed characteristics of ASE are presented. With the increasing discharge power, the size and the number of negative and positive power absorption regions evolve into several distinct patterns. For the low discharge power (at 156.9 W), theremore » is one area of positive and one area of negative power absorption in the radial direction. For the medium discharge power (279 W–683.5 W), there are two areas of negative and two areas of positive power absorption. For the even higher discharge power (above 803.5 W), the number of areas is the same as that of the medium discharge power, but the size of the inner positive and negative power absorption areas is approximately doubled and halved, respectively, while the outer positive and negative power absorption areas slightly shrinks. The evolution of positive and negative power absorption regions is explained as a result of electron thermal diffusion and the energy conversion between rf current and electric field. The spatial decays of electric field and current density are also elucidated by linking them with the positive and negative power absorption pattern.« less