PMID- 32361280
OWN - NLM
STAT- PubMed-not-MEDLINE
LR  - 20200527
IS  - 1879-2723 (Electronic)
IS  - 0304-3991 (Linking)
VI  - 213
DP  - 2020 Jun
TI  - Unravelling new principles of site-selective doping contrast in the dual-beam 
      focused ion beam/scanning electron microscope.
PG  - 112947
LID - S0304-3991(19)30232-3 [pii]
LID - 10.1016/j.ultramic.2020.112947 [doi]
AB  - Doping contrast using the secondary electron (SE) signal in the scanning electron 
      microscope (SEM) can satisfy the International Roadmap for Semiconductors (ITRS) 
      requisites for quantitative dopant profiling of next-generation integrated 
      circuits and devices, but only if adopting a site-selective specimen preparation 
      procedure. In this study, site-specific dopant profiling was performed on the 
      trench side-wall cut by a 30-kV Ga(+) focused ion beam (FIB) into silicon p-n 
      junction specimens and milled using successively lower voltages in the dual-beam 
      FIB/SEM. Although depositing the protective platinum strap on the surface 
      effectively controls 'curtaining' effects at low final milling voltages, 
      significantly reduced doping contrast from the side-wall compared to that from a 
      cleaved surface subjected to the same ion-beam energy is ascribed to the material 
      affected by a previous milling step, as well as the dissimilar geometries of 
      milling and imaging. New principles underpinning the doping contrast mechanism 
      were surveyed taking into account the depth and concentration of ion implantation 
      and amorphization damage as a linear function of the final milling voltage. Patch 
      fields are suppressed, but the bulk doping-dependent surface band-bending fields 
      at the amorphous-crystalline interface is crucial for doping contrast. In 
      general, as the milling voltage decreases the doping contrast increases, which 
      although reaches up to only half that attainable from a freshly-cleaved specimen, 
      is usable, and demonstrates the feasibility of site-specific dopant profiling in 
      situ in the SEM.
CI  - Copyright (c) 2020 Elsevier B.V. All rights reserved.
FAU - Chee, Augustus K W
AU  - Chee AKW
AD  - Centre for Advanced Photonics and Electronics, Electrical Engineering Division, 
      Department of Engineering, University of Cambridge, 9 JJ Thomson Avenue, 
      Cambridge CB3 0FA, United Kingdom; Department of Materials Science and 
      Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, 
      United Kingdom. Electronic address: augustus-chee@cantab.net.
LA  - eng
PT  - Journal Article
DEP - 20200127
PL  - Netherlands
TA  - Ultramicroscopy
JT  - Ultramicroscopy
JID - 7513702
SB  - IM
OTO - NOTNLM
OT  - Amorphous damage
OT  - Dopant profiling
OT  - Focused ion beam
OT  - Ga(+) ions
OT  - Low-voltage milling
OT  - Microfabrication
OT  - Scanning electron microscope
OT  - Semiconductor metrology
OT  - Surface band-bending
OT  - p-n junctions
OT  - secondary electron emission
COIS- Declaration of Competing Interest The authors declare that they have no known 
      competing financial interests or personal relationships that could have appeared 
      to influence the work reported in this paper.
EDAT- 2020/05/04 06:00
MHDA- 2020/05/04 06:01
CRDT- 2020/05/04 06:00
PHST- 2019/06/30 00:00 [received]
PHST- 2019/12/17 00:00 [revised]
PHST- 2020/01/26 00:00 [accepted]
PHST- 2020/05/04 06:00 [pubmed]
PHST- 2020/05/04 06:01 [medline]
PHST- 2020/05/04 06:00 [entrez]
AID - S0304-3991(19)30232-3 [pii]
AID - 10.1016/j.ultramic.2020.112947 [doi]
PST - ppublish
SO  - Ultramicroscopy. 2020 Jun;213:112947. doi: 10.1016/j.ultramic.2020.112947. Epub 
      2020 Jan 27.