Medium energy ion scattering for the characterisation of damage profiles of ultra shallow B implants in Si

Citation
Ja. Van Der Berg et al., Medium energy ion scattering for the characterisation of damage profiles of ultra shallow B implants in Si, NUCL INST B, 183(1-2), 2001, pp. 154-165
Citations number
38
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Spectroscopy /Instrumentation/Analytical Sciences","Instrumentation & Measurement
Journal title
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS
ISSN journal
0168-583X → ACNP
Volume
183
Issue
1-2
Year of publication
2001
Pages
154 - 165
Database
ISI
SICI code
0168-583X(200107)183:1-2<154:MEISFT>2.0.ZU;2-N
Abstract
High depth resolution medium energy ion scattering (MEIS) in the double ali gnment mode has been used to determine the pre- and post-annealing damage d istributions following 0.1-2.5 keV B+ implantation into Si(100) at differen t substrate temperatures. Samples were irradiated to doses ranging from 1 x 10(14) to 2 x 10(16) cm(-2) at substrate temperatures of -150 degreesC, 25 degreesC and 300 degreesC. Rapid thermal processing (RTP) was carried out to temperatures ranging from 400 degreesC to 1000 degreesC for 10 s, to mon itor the annealing of damage caused by the B+ implant. For the room temperature (RT) implants, two distinct damage distributions w ere observed. The first was a narrow, near-surface damage peak which grows out from the virgin Si surface peak to a maximum depth of 3 nm, much shallo wer than the TRIM predicted mean projected range of e.g, 1 keV B+ ions (R-p approximate to 5.3 nm), The width of this damage layer showed only a weak dependence on the B+ ion energy and strong dependence on the dose. The numb er of displaced atoms in this layer for dilute damage conditions is in good agreement with modified Kinchin Pease predictions. For 1 keV B+, a second, deeper damage peak appeared only after a B dose of 1 x 10(15) cm(-2), havi ng a maximum at a depth of approximate to7.5 nm, well beyond the R-p of 5.3 nm. MEIS showed that this post-implant damage structure which develops for irradiations performed at 25 degreesC and 300 degreesC, is the result of d ynamic annealing processes that are highly effective in the region in betwe en the two peaks, in which Frenkel defects have their maximum production ra tes. The observed growth of the surface damage layer with implant dose is a scribed to the migration of point defects, created along the bombardment ca scade, to the Si/SiO2 interface. For 500 eV B+ implants, due to proximity o f this surface sink, the residual damage is greater even at 300 degreesC. I mplantations at -120 degreesC resulted in a single, heavily damaged layer s tretching from the surface to the position of the deep damage. These damage profiles show a direct correlation between the displaced Si and the implan ted B distributions. MEIS yields approached random level, showing near or t otal amorphisation of the Si lattice: epitaxial regrowth, even after 30 s R TP at 600 degrees, was however only partial, apparently arrested at B conta ining I clusters formed near R-p of the B distribution. RTP at 400 degreesC and 500 degreesC of the samples implanted at room tempe rature leads to substantial reduction in the Si damage. especially in the w idth of the near-surface peak, it suggests a substantial rearrangement of S i atoms in the lattice that occurs without the release of Si interstitials, in view of the absence of TED at these temperatures and may involve a degr ee of realignment of the damage structure with the channelling direction. T he annealing behaviour measured by MEIS at higher temperatures is consisten t with XTEM observations, showing the formation and growth in size of exten ded interstitial defects and their ultimate dissolution at high temperature . As well as moving into the bulk where they cause TED, a fraction of the r eleased interstitials migrate to the surface and increase the width of the surface damage region. MEIS studies also indicates the occurrence of revers e annealing for high temperature implant conditions. (C) 2001 Elsevier Scie nce B.V, All rights reserved.