Probe assisted localized doping of aluminum into silicon substrates

Precise control of dopant placement is crucial for the reproducible, and reliable, nanoscale semiconductor device fabrication. In this paper, we demonstrate an atomic force microscopy (AFM) probe assisted localized doping of aluminum into an n-type silicon (100) wafer to generate nanoscale counter-d...

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Bibliographic Details
Published in:Journal of applied physics 2019-02, Vol.125 (7)
Main Authors: Ahn, Jung-Joon, Solares, Santiago D., You, Lin, Noh, Hanaul, Kopanski, Joseph, Obeng, Yaw
Format: Article
Language:English
Subjects:
Aluminum
Applied physics
Atomic force microscopy
Blurring
Chemical potential
Contact potentials
Contaminants
Dopants
Doping
Dwell time
Electric contacts
Electrical junctions
Heat treatment
Implantation
Organic chemistry
Silicon
Silicon substrates
Spatial resolution
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Summary:Precise control of dopant placement is crucial for the reproducible, and reliable, nanoscale semiconductor device fabrication. In this paper, we demonstrate an atomic force microscopy (AFM) probe assisted localized doping of aluminum into an n-type silicon (100) wafer to generate nanoscale counter-doped junctions within two nanometers of the silicon-air interface. The local doping results in changes in electrostatic potential, which are reported as contact potential difference, with nanoscale spatial resolution. In contrast to the literature where nano-mechanical defects in, or contaminants on, silicon substrates can result in measurable changes in the chemical potential of the near-surface, additional thermal treatment was needed to electrically activate the aluminum dopants in our current work. Unfortunately, the thermal activation step also caused the dopants to diffuse and geometric distortions in the doped area, i.e., broadening and blurring of the electrically distinct areas. The results from optimization efforts show that the “active” dopant concentration depended primarily on the thermal anneal temperature; additional AFM-tip dwell time during the aluminum implantation step had no meaningful impact on the electrical activity of the doped sites.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.5065385