AVS 46th International Symposium
    Plasma Science and Technology Division Thursday Sessions
       Session PS2-ThA

Invited Paper PS2-ThA1
Power Modulated, Inductively-Coupled Plasmas

Thursday, October 28, 1999, 2:00 pm, Room 609

Session: Pulsed Plasmas
Presenter: M.V. Malyshev, Bell Laboratories, Lucent Technologies
Authors: M.V. Malyshev, Bell Laboratories, Lucent Technologies
V.M. Donnelly, Bell Laboratories, Lucent Technologies
J.I. Colonell, Bell Laboratories, Lucent Technologies
K.H.A. Bogart, Bell Laboratories, Lucent Technologies
S. Samukawa, NEC Corporation, Japan
Correspondent: Click to Email
A review of plasma behavior in a power modulated (pulsed plasma) mode will be presented. Time dependencies of electron, positive ion, and negative ion densities as well as electron temperatures and electron energy distribution functions were measured with Langmuir probe, microwave interferometry, and TRG-OES in chlorine containing plasmas. Transition from an electropositive plasma to an ion-ion plasma in the afterglow of the pulsing period will be discussed. Formation of an ion-ion plasma is observed in higher pressure/lower power plasmas where Cl@sub 2@ is dissociated to a lesser degree and significant deinsities of negative ions can be produced through dissociative attachment of Cl@sub 2@. Anisotropic etching in inductively-coupled plasmas requires the use of bias and the effect of rf bias on the pulsed plasma mode of operation will be reviewed. In particular, the transition of the decaying plasma in the late afterglow into an RIE-type plasma during pulsed source and continuous bias operation will be shown and discussed. In this regime of operation, electron temperature sharply decreases in the beginning of the OFF cycle, goes through the minimum, and increases when the capacitive sheath near the wafer starts to heat electrons once the plasma density has decayed to RIE levels. Pulsed-power operation expands the boundaries of traditional plasma processing, and is a promising candidate for reducing plasma-induced damage and profile anomalies during plasma etching. Metal etching results in Lam 9600 TCP reactor show an 80% decrease of the severity of the device damage at an optimum condition of 50 µs ON and 50 µs OFF as compared to that of a continuous wave plasma. The use of power modulation for studying fundamental plasma dynamics will also be discussed.