AVS 50th International Symposium
    Plasma Science and Technology Thursday Sessions
       Session PS-ThA

Paper PS-ThA5
Study of Pulsed Plasma Doping System by Time-resolved Ion Mass-energy Spectrometry

Thursday, November 6, 2003, 3:20 pm, Room 315

Session: Plasma Diagnostics: Mechanisms
Presenter: L. Godet, VSEA, France
Authors: L. Godet, VSEA, France
B.-W. Koo, VSEA, France
G. Cartry, Institut des Materiaux de Nantes, France
C. Cardinaud, Institut des Materiaux de Nantes, France
Z. Fang, VSEA, France
A. Grouillet, STMicroelectronics, France
D. Lenoble, STMicroelectronics, France
Correspondent: Click to Email
Pulsed PLAsma Doping (P@super 2@LAD) continues to emerge as a viable alternative technique to ion implantation for advanced semiconductor devices,@footnote 1@ since it is capable of delivering high rate dose at ultra low energy (100V to 10kV applied voltage) giving rise to ultra shallow junctions.@footnote 2@ In P@super 2@LAD, plasma is ignited and extinguished with each negative voltage pulse applied to the wafer. During the pulse, positive ions are accelerated across the sheath and implanted within the wafer. This process was studied using a Hiden EQP mass spectrometer implemented within the pulsed electrode, focussing principally on BF@sub 3@ plasma for different implant process conditions. Previous work, employing time averaged mass spectrometry,@footnote 3@ indicated that BF@sub 2@@super +@ is the dominant ion species in the BF@sub 3@ plasmas, and BF@super +@ is the second most abundant ion species. Due to the short (10 - 50µs) pulse length and low repetition rate (100 - 5000Hz) of the P@super 2@LAD process, the time between the pulses is relatively long so that a time-resolved ion mass-energy measurement is necessary to follow the process before, during and after the pulse period. Time resolved Langmuir probe measurements@footnote 4@ have shown the presence of a cold plasma during the afterglow which may be a key parameter for understanding and controlling the entire process (i.e. charge neutralization, etching, deposition). In this paper, we present time-resolved mass spectrometry data allowing a more complete understanding of BF@sub 3@ P@super 2@LAD processing including the role of negative charges during the afterglow period. @FootnoteText@@footnote 1@D.Lenoble et al., Ion Implantation Technology 2002, Taos, USA.@Footnote 2@R.B. Liebert et al., Ion Implantation Technology 2000, Alpbach, Austria.@footnote 3@B.W. Koo, Z.Fang, S.Felch, Ion Implantation Technology 2000, Alpbach, Austria@footnote 4@Z.Fang et al., Ion Implantation Technology 2002, Taos, US.