Article

Arsenic dopant mapping in State-of-the-art semiconductor devices using electron energy loss spectroscopy

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Abstract

Knowledge of the dopant distribution in nanodevices is critical for optimising their electrical performances. We demonstrate with a scanning transmission electron microscope the direct detection and two-dimensional distribution maps of arsenic dopant in semiconductor silicon devices using electron energy-loss spectroscopy. The technique has been applied to 40-45nm high density static random access memory and to n-p-n BiCMOS transistors. The quantitative maps have been compared with secondary ion mass spectrometry analysis and show a good agreement. The sensitivity using this approach is in the low 10(19)cm(-3) range with a spatial resolution of about 2nm.

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... The local dopant concentration in some semiconductor devices has become high enough to be detectable by EELS. Servanton and Pantel (2010) have shown that STEM-EELS (based on the As-L 23 ionization edge) can map the distribution of arsenic dopant in silicon BiCMOS transistors and static RAM. Their sensitivity was in the low end of the 10 19 cm -3 range, with a spatial resolution about 2 nm; see Fig. 5.54. ...
... In a semiconductor, the main plasmon peak represents resonance of the valence electrons, whose effective mass may differ from that of the conduction electrons. Nevertheless, Gass et al. (2006a) reported Servanton and Pantel (2010), copyright Elsevier agreement with the cyclotron-resonance mass for GaAs and GaN, then used their STEM-EELS system to produce maps of effective mass in InAs quantum dots and GaInNAs quantum wells. ...
Chapter
Electron energy-loss spectroscopy (EELS) involves analyzing the energy distribution of initially monoenergetic electrons after they have interacted with a specimen. This interaction is sometimes confined to a few atomic layers, as when a beam of low-energy (100–1000 eV) electrons is “reflected” from a solid surface. Because high voltages are not involved, the apparatus is relatively compact but the low penetration depth implies the use of ultrahigh vacuum. Otherwise information is obtained mainly from the carbonaceous or oxide layers on the specimen’s surface. At these low primary energies, a monochromator can reduce the energy spread of the primary beam to a few millielectron volts (1991) and if the spectrometer has comparable resolution, the spectrum contains features characteristic of energy exchange with the vibrational modes of surface atoms, as well as valence electron excitation in these atoms. The technique is therefore referred to as high-resolution electron energy-loss spectroscopy (HREELS) and is used to study the physics and chemistry of surfaces and of adsorbed atoms or molecules. Although it is an important tool of surface science, HREELS uses concepts that are somewhat different to those involved in electron microscope studies and will not be discussed further in the present volume. The instrumentation, theory, and applications of HREELS are described by Ibach and Mills (1982) and by Kesmodel (2006).
... Sizeeffects induced by the differences in local dimensions can change the chemistry and properties of the finished material. 8 These may pass unnoticed if only a large test zone is studied. It is therefore important to analyse the nanometric active device or region of interest (ROI). ...
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Two types of industrial transistor technologies have been studied using atom probe tomography (APT). Both 14 nm node high-K metal-oxide-semiconductor field effect transistors (MOSFETs) on ultrathin body and buried oxide and 320 GHz Ft Si/SiGe Heterojunction Bipolar Transistors (HBT) embedded in a 55-nm BiCMOS chip have been analysed and their atomic distribution has been mapped. Due to the limitations of routine characterisation techniques, boron can remain invisible in such nanometric sized structures. Also, size effects can induce differences between the actual device and larger test zones used for monitoring these technologies. This paper presents results obtained by APT from two advanced nodes, in contrast to complementary techniques. Using different methodologies, including specific APT-friendly test structures and multiple-impact data filtering, the dopant behaviour in these structures can be better understood. An unexpected boron distribution in both the MOSFET source/drain and HBT base regions has been highlighted.
... The detailed metalloids contents of ECs are shown in SI Tables S14 and S15. Small amounts of these elements are used as semiconductor materials in ECs (Miao et al., 2017;Servanton and Pantel, 2010;Sivaprakash et al., 2021). Twelve groups of ECs have detected boron (0-6405 mg/kg), with a total average content of 1988 mg/kg, relatively abundant than the other two metalloids. ...
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Off-axis electron holography of electrostatic potentials in unbiased and reverse biased focused ion beam milled semiconductor devices Voyles Atomic-scale imaging of individual dopant atoms and clusters in highly n-type bulk Si
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  • P H Gossmann
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Quantitative dopant profiling of laser annealed FIB-prepared silicon n–p junctions with nm-scale resolution
  • Cooper
Cooper,D., etal.,2007.QuantitativedopantprofilingoflaserannealedFIB-prepared silicon n–p junctions with nm-scale resolution. Appl. Phys. Lett. 91, 143501
First performance measurements and application results of a new high brightness Schottky field emitter for HR-S/TEM at 80–300 kV accel-eration voltage Nickel silicide encroachment formation and characteriza-tion
  • B Freitag
Freitag, B., et al., 2008. First performance measurements and application results of a new high brightness Schottky field emitter for HR-S/TEM at 80–300 kV accel-eration voltage. Microsc. Microanal.. Imbert, B., et al., 2009. Nickel silicide encroachment formation and characteriza-tion. Microelectron. Eng. (online in June 2009).
Imaging of arsenic cottrell atmospheres around silicon defects by three-dimensional atom probe tomography Direct atomic scale characterization of interfaces and doping layers in field-effect transistors
  • K Thompson
  • P L Flaitz
  • P Ronsheim
  • D J Larson
  • T F Kelly
Thompson, K., Flaitz, P.L., Ronsheim, P., Larson, D.J., Kelly, T.F., 2007. Imaging of arsenic cottrell atmospheres around silicon defects by three-dimensional atom probe tomography. Science 317, 1370. Topuria, T., James, E.M., Browning, N.D., 2001. Direct atomic scale characterization of interfaces and doping layers in field-effect transistors. Appl. Phys. Lett. 79, 132.
Analytical STEM comparative study of the incorporation of covalent (Ge) or heterovalent (As) atoms in silicon crystal Two-dimensional quantitative mapping of arsenic in nanometer-scale silicon devices using STEM EELS-EDX spectroscopy
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Pantel, R., Clement, L., Rubaldo, L., Borot, G., Dutartre, D., 2008. Analytical STEM comparative study of the incorporation of covalent (Ge) or heterovalent (As) atoms in silicon crystal. Microscopy of Semiconducting Materials, vol. 120. Springer. Servanton, G., Pantel, R., Juhel, M., Bertin, F., 2009. Two-dimensional quantitative mapping of arsenic in nanometer-scale silicon devices using STEM EELS-EDX spectroscopy. Micron 40, 543. Servanton, G., Pantel, R., Juhel, M., Bertin, F., Submitted for publication. STEM EDX applications for arsenic dopant mapping in nanometer-scale silicon devices. Proceedings of the 16th Conference Microscopy of Semiconducting Materials, March 2009.
Dopant mapping for the nanotech-nology age Quantitative dopant profiling of laser annealed FIB-prepared silicon n–p junctions with nm-scale resolution
  • M R Castell
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  • P M Voyles
  • D Cooper
Castell, M.R., Muller, D.A., Voyles, P.M., 2003. Dopant mapping for the nanotech-nology age. Nat. Mater. 2, 129. Cooper, D., et al., 2007. Quantitative dopant profiling of laser annealed FIB-prepared silicon n–p junctions with nm-scale resolution. Appl. Phys. Lett. 91, 143501.
See http://public. itrs.net for details
International Technology Roadmap for Semiconductors, 2009. See http://public. itrs.net for details.
First performance measurements and application results of a new high brightness Schottky field emitter for HR-S/TEM at 80-300 kV acceleration voltage
  • B Freitag
Freitag, B., et al., 2008. First performance measurements and application results of a new high brightness Schottky field emitter for HR-S/TEM at 80-300 kV acceleration voltage. Microsc. Microanal..
Atomic-scale imaging of individual dopant atoms and clusters in highly n-type bulk Si
  • Voyles