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Title: Characteristics of pulsed plasma doping sources for ultrashallow junction formation

Abstract

Plasma doping of semiconductors is being investigated for low energy ion implantation to form ultrashallow junctions. In plasma doping, ions are extracted from a quasicontinuous plasma using a pulsed bias on the substrate. Plasma-based implantation techniques have the potential for higher throughput than those attainable with conventional accelerator beamlines due to the higher current densities possible with plasma sources. In this work, results from a computational investigation of plasma sources for doping of semiconductors will be discussed. An inductively coupled plasma (ICP) was used to generate ions at pressures of a few to tens of millitorr. A pulsed bias up to -20 kV having lengths of tens of microseconds was applied to the substrate to accelerate the ions. Results are presented for Ar/NF{sub 3} gas mixtures which serve as surrogates for the Ar/BF{sub 3} mixtures that would provide boron doping. The consequences of bias voltage waveform, ICP power, operating pressure, and aspect ratio of the reactor on discharge characteristics and ion energy and angular distributions (IEADs) to the substrate will be discussed. The shape of the bias waveform has important consequences on the IEADs not only because of the transit times of the ions but also due to the instabilitiesmore » that may be launched into the plasma. The aspect ratio of the reactor influences the angular uniformity of the IEADs, particularly when using large biases.« less

Authors:
;  [1];  [2]
  1. Department of Chemical and Biomolecular Engineering, University of Illinois, Urbana, Illinois 61801 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
20982750
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 101; Journal Issue: 6; Other Information: DOI: 10.1063/1.2433746; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 36 MATERIALS SCIENCE; ACCELERATORS; ANGULAR DISTRIBUTION; ARGON; ASPECT RATIO; BORON; BORON FLUORIDES; CURRENT DENSITY; ELECTRIC POTENTIAL; ION IMPLANTATION; IONS; MIXTURES; NITROGEN FLUORIDES; PLASMA; PLASMA INSTABILITY; SEMICONDUCTOR JUNCTIONS; SEMICONDUCTOR MATERIALS; SUBSTRATES; WAVE FORMS

Citation Formats

Agarwal, Ankur, Kushner, Mark J., and Department of Electrical and Computer Engineering, Iowa State University, 104 Marston Hall, Ames, Iowa 50011-2151. Characteristics of pulsed plasma doping sources for ultrashallow junction formation. United States: N. p., 2007. Web. doi:10.1063/1.2433746.
Agarwal, Ankur, Kushner, Mark J., & Department of Electrical and Computer Engineering, Iowa State University, 104 Marston Hall, Ames, Iowa 50011-2151. Characteristics of pulsed plasma doping sources for ultrashallow junction formation. United States. doi:10.1063/1.2433746.
Agarwal, Ankur, Kushner, Mark J., and Department of Electrical and Computer Engineering, Iowa State University, 104 Marston Hall, Ames, Iowa 50011-2151. Thu . "Characteristics of pulsed plasma doping sources for ultrashallow junction formation". United States. doi:10.1063/1.2433746.
@article{osti_20982750,
title = {Characteristics of pulsed plasma doping sources for ultrashallow junction formation},
author = {Agarwal, Ankur and Kushner, Mark J. and Department of Electrical and Computer Engineering, Iowa State University, 104 Marston Hall, Ames, Iowa 50011-2151},
abstractNote = {Plasma doping of semiconductors is being investigated for low energy ion implantation to form ultrashallow junctions. In plasma doping, ions are extracted from a quasicontinuous plasma using a pulsed bias on the substrate. Plasma-based implantation techniques have the potential for higher throughput than those attainable with conventional accelerator beamlines due to the higher current densities possible with plasma sources. In this work, results from a computational investigation of plasma sources for doping of semiconductors will be discussed. An inductively coupled plasma (ICP) was used to generate ions at pressures of a few to tens of millitorr. A pulsed bias up to -20 kV having lengths of tens of microseconds was applied to the substrate to accelerate the ions. Results are presented for Ar/NF{sub 3} gas mixtures which serve as surrogates for the Ar/BF{sub 3} mixtures that would provide boron doping. The consequences of bias voltage waveform, ICP power, operating pressure, and aspect ratio of the reactor on discharge characteristics and ion energy and angular distributions (IEADs) to the substrate will be discussed. The shape of the bias waveform has important consequences on the IEADs not only because of the transit times of the ions but also due to the instabilities that may be launched into the plasma. The aspect ratio of the reactor influences the angular uniformity of the IEADs, particularly when using large biases.},
doi = {10.1063/1.2433746},
journal = {Journal of Applied Physics},
number = 6,
volume = 101,
place = {United States},
year = {Thu Mar 15 00:00:00 EDT 2007},
month = {Thu Mar 15 00:00:00 EDT 2007}
}
  • By means of GILD (gas immersion laser doping) on the surface of n-type Si samples, with BBr/sub 3/ vapor as the working material, Si-photocells doped with boron have been fabricated. The maximum doping concentration is 1.2 x 10/sup 21/ B/sup +//cm/sup 3/ near the surface, the junction depth is 0.08 ..mu..m at 10/sup 17/ B/sup +//cm/sup 3/, and the conversion efficiency is about 9.5% without antireflection coatings.
  • This paper describes a one-dimensional numerical analysis of heat and mass diffusion of the boron atoms across a thin molten silicon layer. The mass diffusion is decoupled from the thermal equations.
  • High-power arc lamp design has enabled ultrahigh-temperature (UHT) annealing as an alternative to conventional rapid thermal processing (RTP) for ultrashallow junction formation. The time duration of the UHT annealing technique is significantly reduced from those obtained through conventional RTP. This difference in time may offer the ability to maintain a highly activated ultrashallow junction without being subjected to transient enhanced diffusion (TED), which is typically observed during postimplant thermal processing. In this study, two 200-mm (100) n-type Czochralski-grown Si wafers were preamorphized with either a 48- or a 5-keV Ge{sup +} implant to 5x10{sup 14} cm{sup 2}, and subsequently implantedmore » with 3-keV BF{sub 2}{sup +} molecular ions to 6x10{sup 14} cm{sup 2}. The wafers were sectioned and annealed under various conditions in order to investigate the effects of the UHT annealing technique on the resulting junction characteristics. The main point of the paper is to show that the UHT annealing technique is capable of producing a highly activated p-type source/drain extension without being subjected to TED only when the preamorphization implant is sufficiently deep.« less
  • For MOS devices belonging to 65 nm technology node and beyond, ultra-shallow LDD junctions are needed in order to match requirements in terms of sheet resistance and doping profile. PLAsma Doping has been proposed and developed as an effective and viable technology capable to produce such junctions, while keeping high productivity. Furthermore, as the equipment is simpler and smaller than a common implanter, PLAsma Doping can be considered, from the cost of ownership point of view, an attractive solution also for those applications whose requirements are not so demanding; an example can be the junctions of a Flash Memory. Aimmore » of this study is to evaluate, electrically, the compatibility of PLAsma Doping with a NOR Flash Memory belonging to 90 nm technology node. Results of PLAsma Doping experiment concerning the matching of the device parameters will be here presented. Further investigation is needed in order to exclude any possible effect on device reliability.« less
  • We have built an analytical time-of-flight instrument capable of sputter-initiated resonance ionization microprobe (SIRIMP) measurements. This instrument has the ability to obtain ultrashallow doping profiles with high depth resolution and dynamic range and virtually no matrix effects. The SIRIMP technique is especially valuable for ultratrace element analysis in samples where the complexity of the matrix is frequently a serious source of interferences. We describe the capability of the SIRIMP technique to quantitate with high accuracy and dynamic range dopant and impurity concentrations in silicon and silicon oxide samples at the 10{sup 13}{endash}10{sup 20} level. For example, the depth profile formore » a Sb implant in silicon shows a dynamic range of greater than 10{sup 7}. Dynamic range and depth resolution, quantitation accuracy, and limitations will be discussed. {copyright} {ital 1996 American Vacuum Society}« less