Costel Biloiu

Ion beam acceleration in a divergent magnetic field

Two-dimensional argon ion velocity distribution functions (IVDFs) in the expansion region of a helicon plasma source have been measured by laser-induced-fluorescence tomography. Below a threshold value of the magnetic field in the expansion region, the IVDFs show a bimodal structure comprised of a supersonic ion population axially moving away from the source and an isotropic, slow, background, ion population. Increasing the magnetic field divergence leads to an increase in the axial speed of the supersonic component. A maximum axial speed of ∼2.9cs was obtained for a source/expansion magnetic field ratio of 43.

One- and two-dimensional laser induced fluorescence at oblique incidence

The diagnostic technique of laser induced fluorescence (LIF), generalized to the case of oblique laser injection angle relative to the local magnetic field direction, is employed for studies of the ion velocity distribution function (IVDF) in the magnetic expansion region of a helicon plasma source. One-dimensional LIF measurements reveal key characteristics of the acceleration mechanism responsible for creation of an ion beam in the expansion regions: a bimodal IVDF comprising a slowly drifting (~150?m?s?1) ion population and a fast ion beam (~10.7?km?s?1). Two-dimensional LIF, LIF tomography, provides additional insight regarding the origins of the two ion populations: the nearly isotropic slow population is a locally created background population whereas the distorted velocity distribution of the fast population is consistent with an origin upstream of the measurement location.

Nitrogen dissociation degree in the diffusion region of a helicon plasma source obtained by atomic lines to molecular band intensities ratio

Estimates of the dissociation degree in the diffusion region of a nitrogen helicon plasma source based on optical emission spectroscopy and Langmuir probe measurements are presented. The estimation procedure relies on measurements of the ratios of the intensities of the atomic triplet 3pS04→3sP4 (742.36, 744.23, and 746.83nm) to the intensity of the 4-2 band of the first positive system (AΣu+3→BΠg3) at 750.39nm and the measured relative vibrational distribution of the BΠg3 state. The electron energy distribution function, obtained from the second derivative of the Langmuir probe characteristic, and published excitation cross sections are used to calculate the electron-impact excitation rate coefficients—which are then compared to the atomic line and molecular band intensities to calculate the dissociation degree. For two distinct operating regimes, capacitively and inductively coupled, dissociation fractions of 5% and 13% are obtained in the expansion region of a 10mTorr, 500W, 10.74MHz helicon generated ...

Plasma-Enhanced Chemical Vapor Deposition of Amorphous Fluorocarbon Polymer Films (

An RF capacitively coupled reactor designed for plasma-enhanced chemical vapor deposition of amorphous fluorocarbon polymer films on spherical surfaces is described. Pictures of the plasma created between the concentrically spherical electrodes, the film surface, and a cross section of the film are presented.

a

A high-uniformity inductively coupled plasma source is presented. The plasma uniformity is improved with a magnetic multicusp structure that surrounds the plasma chamber. A picture showing the alternating bright and dark plasma regions along the perimeter of the plasma chamber-an effect of the magnetic confinement-is presented as well.

-C:F) on Spherical Surfaces

Wafer charging effects that result from the ion implantation process are typically mitigated by employing a plasma flood gun to provide electrons to neutralize the positive ion beam as it strikes the wafer surface. As gate oxide thickness of semiconductor devices continues to shrink, control of the wafer charge‐up during ion implantation becomes critical. Varian Semiconductor Equipment Associates (VSEA) has designed and built a real time charge monitor (RTCM) for in situ measurement of the beam‐induced charging potential. Mounted close to the wafer and in the beam path, the RTCM continuously measures the deviation from quasi‐neutrality as the wafer passes through the beam. In this paper we present reliability tests of this device for high current implanters over varied implantation conditions and failure modes. When correlated with the yield of antenna device test wafers, it was found that the RTCM signal is a sensitive and reliable tool to predict charging damage to the semiconductor devices.