AVS 46th International Symposium
    Plasma Science and Technology Division Friday Sessions
       Session PS-FrM

Paper PS-FrM3
Sputter-Wind Heating in Ionized Metal PVD@footnote 1@

Friday, October 29, 1999, 9:00 am, Room 609

Session: Emerging Plasma Applications
Presenter: J. Lu, University of Illinois, Urbana
Authors: J. Lu, University of Illinois, Urbana
M.J. Kushner, University of Illinois, Urbana
Correspondent: Click to Email
Ionized metal physical vapor deposition (IMPVD) is used to deposit seed layers and/or diffusion barriers in high aspect ratio trenches and vias for microelectronics fabrication. The physical sputtering is generated from a magnetron cathode. A secondary plasma is generated between the cathode and the substrate by an rf antenna. Experimental measurements suggest that sputter heating, generated by momentum and energy transfer from the sputtered metal atoms and the background gas atoms, rarifies the background gas and affects the transport of the sputtered atoms. In this study, sputter wind heating in IMPVD reactors is investigated using the Hybrid Plasma Equipment Model (HPEM) which has been improved to include processes relevant to sputter heating. These processes include ion energy-dependent yield, ion-energy dependent sputtered atom kinetic energy distribution, and heating due to the sputtered atoms. Improved algorithms have also been developed for electron transport in high magnetic fields to fully resolve the magnetron effect. The transport of the sputtered atoms is treated with a Monte-Carlo simulation. Statistics are collected on the interaction of sputtered atoms with the background gas, and are used to generate source terms in the continuity, momentum, and energy equations. Parametric studies have been performed for sputter heating in aluminum and copper IMPVD systems operating at low to high powers (up to 1500 W ICP, and 2000 W magnetron), and low to high reactor aspect ratio (height to radius) in 10's mTorr Ar. Due to the rarefaction in front of the target which results from sputter-wind heating, the slowing down length for sputtered atoms increases, thereby changing the flux of sputtered atoms to the substrate. Commensurate changes in the ion current to the target shift its I-V characteristics. @FootnoteText@ @footnote 1@This work was supported by SRC and TAZ.