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Title: Investigation of a rf inductively coupled plasma ion source capable of highly uniform and collimated ion-beam generation

Abstract

In accordance with advanced data storage device fabrication requirements, we have evaluated a new broad-beam rf ion source for ion beam etching and deposition application. This source utilizes a novel reentrant shaped plasma inductively coupled plasma generator for improved radial plasma density uniformity and a dynamic magnetic field for improved static etch uniformity. It has the capability of reproducibly generating extremely uniform ion beams from 500 to 1500 eV with divergence angle <3 deg. and high directionality [Kanarov et al. (patent pending)]. For a 150 mm diameter wafer, an etch uniformity of <1% {sigma}/mean in static condition or <0.5% with wafer rotation is obtained over an ion incident angle range of 0 deg. - 65 deg. Recently, we have investigated extending the operation of this source to the critical low energy range, 100-500 eV, required for fabricating thin film magnetic head sensors. It was found that, under optimum operating conditions, excellent static etch uniformity (1%-1.5% {sigma}/mean) could be obtained at high ion beam current densities, up to 0.5 mA/cm{sup 2}, over the entire low-energy range while still achieving low divergence angles (<5 deg.) and high beam directionality. The ion beam performance was consistent with results obtained by simulation and bymore » experiment using a 19-hole array ion optic test stand with scanning ion probe [E. Waahlin (unpublished)]. In this article we will describe the design of the ion source and then present the experimental performance data including plasma density distribution measured by an array of flat Langmuir probes, beam divergence distribution obtained by a 'pepper-pot' etch measurement technique, and etching rate distributions.« less

Authors:
; ; ; ; ;  [1];  [2]
  1. Veeco Instruments, Inc., Terminal Drive, Plainview, New York 11803 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
20779072
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 77; Journal Issue: 3; Conference: 11. international conference on ion sources, Caen (France), 12-16 Sep 2005; Other Information: DOI: 10.1063/1.2172349; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; CURRENT DENSITY; DEPOSITION; DISTRIBUTION; ETCHING; FABRICATION; ION BEAMS; ION PROBES; ION SOURCES; IONS; LANGMUIR PROBE; MAGNETIC FIELDS; MEMORY DEVICES; PERFORMANCE; PLASMA; PLASMA DENSITY; SIMULATION; THIN FILMS

Citation Formats

Kanarov, V., Hayes, A., Yevtukhov, R., Kameyama, I., Siegfried, D., Waahlin, E., and Veeco Instruments, Inc., 2330 East Prospect, Fort Collins, Colorado 80525. Investigation of a rf inductively coupled plasma ion source capable of highly uniform and collimated ion-beam generation. United States: N. p., 2006. Web. doi:10.1063/1.2172349.
Kanarov, V., Hayes, A., Yevtukhov, R., Kameyama, I., Siegfried, D., Waahlin, E., & Veeco Instruments, Inc., 2330 East Prospect, Fort Collins, Colorado 80525. Investigation of a rf inductively coupled plasma ion source capable of highly uniform and collimated ion-beam generation. United States. doi:10.1063/1.2172349.
Kanarov, V., Hayes, A., Yevtukhov, R., Kameyama, I., Siegfried, D., Waahlin, E., and Veeco Instruments, Inc., 2330 East Prospect, Fort Collins, Colorado 80525. Wed . "Investigation of a rf inductively coupled plasma ion source capable of highly uniform and collimated ion-beam generation". United States. doi:10.1063/1.2172349.
@article{osti_20779072,
title = {Investigation of a rf inductively coupled plasma ion source capable of highly uniform and collimated ion-beam generation},
author = {Kanarov, V. and Hayes, A. and Yevtukhov, R. and Kameyama, I. and Siegfried, D. and Waahlin, E. and Veeco Instruments, Inc., 2330 East Prospect, Fort Collins, Colorado 80525},
abstractNote = {In accordance with advanced data storage device fabrication requirements, we have evaluated a new broad-beam rf ion source for ion beam etching and deposition application. This source utilizes a novel reentrant shaped plasma inductively coupled plasma generator for improved radial plasma density uniformity and a dynamic magnetic field for improved static etch uniformity. It has the capability of reproducibly generating extremely uniform ion beams from 500 to 1500 eV with divergence angle <3 deg. and high directionality [Kanarov et al. (patent pending)]. For a 150 mm diameter wafer, an etch uniformity of <1% {sigma}/mean in static condition or <0.5% with wafer rotation is obtained over an ion incident angle range of 0 deg. - 65 deg. Recently, we have investigated extending the operation of this source to the critical low energy range, 100-500 eV, required for fabricating thin film magnetic head sensors. It was found that, under optimum operating conditions, excellent static etch uniformity (1%-1.5% {sigma}/mean) could be obtained at high ion beam current densities, up to 0.5 mA/cm{sup 2}, over the entire low-energy range while still achieving low divergence angles (<5 deg.) and high beam directionality. The ion beam performance was consistent with results obtained by simulation and by experiment using a 19-hole array ion optic test stand with scanning ion probe [E. Waahlin (unpublished)]. In this article we will describe the design of the ion source and then present the experimental performance data including plasma density distribution measured by an array of flat Langmuir probes, beam divergence distribution obtained by a 'pepper-pot' etch measurement technique, and etching rate distributions.},
doi = {10.1063/1.2172349},
journal = {Review of Scientific Instruments},
number = 3,
volume = 77,
place = {United States},
year = {Wed Mar 15 00:00:00 EST 2006},
month = {Wed Mar 15 00:00:00 EST 2006}
}
  • The variations of plasma parameters on the boundary conditions, especially potential, of plasmas were measured in an inductively coupled plasma source developed to generate a hyperthermal neutral beam. Hyperthermal neutrals can be produced by Auger neutralization when ions with low energy are neutralized by impinging on a metal surface called a reflector. However, the reflector is a significant source of ion drain when it is biased to a negative potential. The plasma potential can be negative with respect to the grounded chamber potential while the reflector is negatively biased, but other plasma parameters, namely density and temperature, are not sensitivemore » to the reflector bias. If the electron loss current into the chamber wall is governed by the space charge limited current law, sustainment of the plasma with a negative potential can be explained in terms of the charge balance equations for quasineutrality.« less
  • Generation of fast ion beams by laser-induced skin-layer ponderomotive acceleration has been studied using a two-dimensional (2D) two-fluid relativistic computer code. It is shown that the key parameter determining the spatial structure and angular divergence of the ion beam is the ratio d{sub L}/L{sub n}, where d{sub L} is the laser beam diameter and L{sub n} is the plasma density gradient scale length. When d{sub L}>>L{sub n}, a dense highly collimated megaampere ion (proton) beam of the ion current density approaching TA/cm{sup 2} can be generated by skin-layer ponderomotive acceleration, even with a tabletop subpicosecond laser.
  • In order to extend the operating range of the GEC RF Reference Cell, the authors developed an inductively coupled plasma source that replaced the standard parallel-plate upper-electrode assembly. Voltage and current probes, Langmuir probes, and an 80 GHz interferometer provided information on plasmas formed in argon, chlorine, and nitrogen at pressures from 0.1 Pa to 3 Pa. For powers deposited in the plasma from 20 W to 300 W, the source produced peak electron densities between 10{sup 10}/cm{sup 3} and 10{sup 12}/cm{sup 3} and electron temperatures near 4 eV. The electron density peaked on axis with typical full-width at halfmore » maximum of 7 cm to 9 cm. Discharges in chlorine and nitrogen had bimodal operation that was clearly evident from optical emission intensity. A dim mode occurred at low power and a bright mode at high power. The transition between modes had hysteresis. After many hours of high-power operation, films formed on electrodes and walls of one Cell. These deposits affected the dim-to-bright mode transition, and also apparently caused generation of hot electrons and increased the plasma potential.« less
  • GaN epilayers have been grown on basal plane (0001) sapphire by plasma-assisted molecular beam epitaxy (MBE) with a novel, inductively coupled nitrogen plasma source. Films grown at 700{degree}C generate stimulated emission at 300 K when optically pumped in vertical geometry with {approximately}3.5 eV ({lambda}=355 nm) photons. The extrapolated pump power threshold is {approximately}3.6 MWcm{sup {minus}2} which corresponds to an absorbed value of 700 kWcm{sup {minus}2} and a peak carrier number density of {approximately}4{times}10{sup 19} cm{sup {minus}3}. {copyright} {ital 1997 American Institute of Physics.}
  • Low-energy neutral beam sources are very promising candidates for realization of next generation ultralarge-scale integrated devices. The use of pulsed inductively coupled plasma and surface (wall) neutralizer appears to be an efficient way of producing high-flux low-energy neutral beams. Measurement of the time evolution of ion fluxes entering the neutralizer plays an essential role in understanding and control of these neutral beam systems. Here the authors present a simple method for measuring the temporal dynamics of ion fluxes in neutral beam source described elsewhere [S. Samukawa et al., J. Vac. Sci. Technol. A 20, 1566 (2002)]. The method is basedmore » on the use of a low aspect ratio orifice in the center of neutralizer, magnetic filter, and Faraday cup. At some conditions, it allows (1) to measure the magnitudes of positive and negative wall ion fluxes in pulsed plasmas with an extremely high temporal resolution (better than 1 {mu}s) and (2) to examine the difference in surface neutralization between positive and negative ions. The measurements show that neutralization of hyperthermal ions is mainly controlled by geometry of plasma sheath adjacent to the surface neutralizer; however, negative ions are neutralized more easily than positive ones. The experimental results for SF{sub 6} (ion-ion) and Ar plasmas in combination with dc/rf bias are reported.« less