AVS 58th Annual International Symposium and Exhibition
    Plasma Science and Technology Division Tuesday Sessions
       Session PS-TuM

Paper PS-TuM10
Superposition of High Negative DC Voltage in Capacitively Coupled Plasma

Tuesday, November 1, 2011, 11:00 am, Room 201

Session: Advanced BEOL / Interconnect Etching I
Presenter: Andrew Metz, TEL Technology Center, America, LLC
Authors: A. Ranjan, TEL Technology Center, America, LLC
A. Metz, TEL Technology Center, America, LLC
A. Lisi, TEL Technology Center, America, LLC
Y. Chiba, TEL Technology Center, America, LLC
W. Li, TEL Technology Center, America, LLC
Y. Feurprier, TEL Technology Center, America, LLC
K. Kumar, TEL Technology Center, America, LLC
P. Biolsi, TEL Technology Center, America, LLC
L. Chen, Tokyo Electron America
P. Ventzek, Tokyo Electron America
R. Sundararajan, Tokyo Electron America
Correspondent: Click to Email
The effects of applying a negative DC voltage to capacitively coupled plasmas (CCP) were investigated using PIC-MCC simulation and experiment. High energy secondary electrons, originating at the electrode with high negative DC voltages (DC electrode), are generated due to ion impact as well as electron-impact. These secondary electrons are accelerated away from the DC electrode by the sheath voltage drop. These secondary electrons gain energy equal to DC voltage drop across the sheath and travel to wafer electrode or get trapped between electrodes. Trapping and dumping of ballistic electrons depends on the voltages on the electrodes. Ballistic electrons alter the bulk electron energy distribution function of the plasma (EEDF), EEDF at wafer, high energy electron flux to wafer and plasma density profiles. Simulation shows that center to edge uniformity, plasma density and EEDF can be tuned by applying negative DC voltage in CCPs. Bulk plasma volume can be modulated by applying negative DC voltage giving us a very effective knob for an “effective” variable gap CCP without moving chamber parts in vacuum. The change in EEDF alters the plasma chemistry, the result of which can be observed by optical emission spectra and blanket etch rate data, validating the changes in chemistry due to superimposed negative DC voltage. Various other interesting aspects will also be presented.