A study of bipolar transistors with polysilicon emitters
A study of bipolar transistors with polysilicon emitters
Silicon bipolar transistors have been fabricated with arsenic implanted or phosphorous diffused polysilicon emitters. The effects of different surface treatments, prior to polysilicon deposition, are investigated by comparing the gain of the resulting transistors. It is shown that the gains of the devices given a dip etch in hydrofluoric acid prior to polysilicon deposition are 3 times higher than conventional transistors, whereas devices given an RCA clean treatment have gains which are 7 to 32 times higher. The latter surface treatment was intended to grow a thin interfacial oxide layer, while the former treatment was intended to give an oxide - free surface. Detailed electrical results are presented for these two types of device, including current - voltage characteristics, gain and resistance under the emitter, all as a function of temperature. These results are explained using theoretical models from the literature.Experiments are carried out to determine which of the constituents of the RCA clean are responsible for the gain improvement. These experiments indicate that the boiling water is largely responsible for the formation of the interfacial layer. Rutherford backscattering is used to provide the arsenic profilesin the polysilicon and single crystal silicon, and to study the crystal structure of the polysilicon. Bevelling and staining is used to provide the junction depths. It is shown that the interfacial layer retards the arsenic diffusion from the polysilicon into the underlying single crystal silicon.
University of Southampton
1983
Soerowirdjo, Busono
(1983)
A study of bipolar transistors with polysilicon emitters.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
Silicon bipolar transistors have been fabricated with arsenic implanted or phosphorous diffused polysilicon emitters. The effects of different surface treatments, prior to polysilicon deposition, are investigated by comparing the gain of the resulting transistors. It is shown that the gains of the devices given a dip etch in hydrofluoric acid prior to polysilicon deposition are 3 times higher than conventional transistors, whereas devices given an RCA clean treatment have gains which are 7 to 32 times higher. The latter surface treatment was intended to grow a thin interfacial oxide layer, while the former treatment was intended to give an oxide - free surface. Detailed electrical results are presented for these two types of device, including current - voltage characteristics, gain and resistance under the emitter, all as a function of temperature. These results are explained using theoretical models from the literature.Experiments are carried out to determine which of the constituents of the RCA clean are responsible for the gain improvement. These experiments indicate that the boiling water is largely responsible for the formation of the interfacial layer. Rutherford backscattering is used to provide the arsenic profilesin the polysilicon and single crystal silicon, and to study the crystal structure of the polysilicon. Bevelling and staining is used to provide the junction depths. It is shown that the interfacial layer retards the arsenic diffusion from the polysilicon into the underlying single crystal silicon.
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Published date: 1983
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Local EPrints ID: 459725
URI: http://eprints.soton.ac.uk/id/eprint/459725
PURE UUID: 1ff13918-159f-42bd-8f29-2fa657aebf1c
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Date deposited: 04 Jul 2022 17:17
Last modified: 04 Jul 2022 17:17
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Author:
Busono Soerowirdjo
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