Semion System Retarding Field Ion Energy Analyzer “

Wafer processing controlled by energy and flux of bombarding ions ­ e.g. etch rate, etched feature quality Ion energy measurement critical for process development Wafer usually processed using RF excitation ­ typically, 2-60MHz Difficult conditions in which to measure IED - electrical filtering, high temperatures, sensor etched or coated during processing RFEA sensor for IED measurements developed, easily incorporated into existing reactors, compatible with majority of substrate bias conditions Importance of ion energy distribution (IED) measurements

RFEA Schematic -60V 0 to +V -70V -60V + Aperture - G1G1 G2G2 G3G3 C G4G4 Insulator Filter Plasma I

Nickel Grid Structure Electron microscope image of a nickel grid

Average ion energy Ion flux IV Curve and Calculated IED

Orifice diameter < Debye length λ D e.g. T e =3eV, N e =10 17 m -3 …… λ D ~40µm Ion transit length < Ion mean free path λ i RFEA depth 0.6mm ~ 100mTorr in Argon Design considerations

Semion Electronics GeneratorMatch Plasma Reactor Computer Installation Located at any location inside a plasma reactor Floating, RF bias, grounded Connected through a vaccum port via ceramic beaded cable

Installation

Shape of IED determined by sheath potential, ion transit time and period of sheath potential waveform. For DC sheath, ~,  E~0 -60V 0 to +V -70V -60V + Aperture - G1G1 G2G2 G3G3 C G4G4 Insulator Filter Plasma I IED

For rf modulated sheath: Ion transit time = IED -60V 0 to +V -70V -60V + Aperture - G1G1 G2G2 G3G3 C G4G4 Insulator Filter Plasma I

IED Shape

Semion Electronics GeneratorMatch Plasma Reactor Computer Results DC Sheath - Pressure

Semion Electronics GeneratorMatch Plasma Reactor Computer Results RF Sheath - Bias

Semion Electronics GeneratorMatch Plasma Reactor Computer Results RF Sheath - Frequency

Spatial Uniformity