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Ion flux and ion distribution function measurements in synchronously pulsed inductively coupled plasmas

Brihoum, Melsia; Cunge, Gilles; Darnon, Maxime; Gahan, David; Joubert, Olivier and Braithwaite, Nicholas St.J (2013). Ion flux and ion distribution function measurements in synchronously pulsed inductively coupled plasmas. Journal of Vacuum Science and Technology A, 31(2), article no. 020604.

DOI (Digital Object Identifier) Link: https://doi.org/10.1116/1.4790364
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Abstract

Changes in the ion flux and the time-averaged ion distribution functions are reported for pulsed, inductively coupled RF plasmas (ICPs) operated over a range of duty cycles. For helium and argon plasmas, the ion flux increases rapidly after the start of the RF pulse and after about 50 μs reaches the same steady state value as that in continuous ICPs. Therefore, when the plasma is pulsed at 1 kHz, the ion flux during the pulse has a value that is almost independent of the duty cycle. By contrast, in molecular electronegative chlorine/chlorosilane plasmas, the ion flux during the pulse reaches a steady state value that depends strongly on the duty cycle. This is because both the plasma chemistry and the electronegativity depend on the duty cycle. As a result, the ion flux is 15 times smaller in a pulsed 10% duty cycle plasma than in the continuous wave (CW) plasma. The consequence is that for a given synchronous RF biasing of a wafer-chuck, the ion energy is much higher in the pulsed plasma than it is in the CW plasma of chlorine/chlorosilane. Under these conditions, the wafer is bombarded by a low flux of very energetic ions, very much as it would in a low density, capacitively coupled plasma. Therefore, one can extend the operating range of ICPs through synchronous pulsing of the inductive excitation and capacitive chuck-bias, offering new means by which to control plasma etching.

Item Type: Journal Item
Copyright Holders: 2013 American Vacuum Society
ISSN: 0734-2101
Project Funding Details:
Funded Project NameProject IDFunding Body
Not SetNot SetPartly funded by French RENA-TECH network.
Extra Information: 6 pp.
Keywords: plasma etching; pulsed plasma; inductively coupled plasma; ICP
Academic Unit/School: Faculty of Science, Technology, Engineering and Mathematics (STEM) > Physical Sciences
Faculty of Science, Technology, Engineering and Mathematics (STEM)
Research Group: Physics
Item ID: 36578
Depositing User: N St.J Braithwaite
Date Deposited: 11 Feb 2013 09:47
Last Modified: 07 Dec 2018 10:13
URI: http://oro.open.ac.uk/id/eprint/36578
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