A study of 1/f noise in polysilicon emitter transistors
A study of 1/f noise in polysilicon emitter transistors
This thesis describes the results of an experimental and theoretical study of 1/f noise in polysilicon emitter bipolar junction transistors. The physical origins of 1/f noise in these devices are investigated by studying devices with different emitter structures, such as RCA, HF, balled-oxide and epitaxially re-aligned devices. The experimental results show that when a thin and continuous layer of oxide is present at the polysilicon/silicon interface (i.e., RCA type devices), the 1/f noise of the device is substantially increased. The results also indicate that treating the devices in HF prior to polysilicon deposition, results in large improvements in the 1/f noise characteristics. Further improvements in the noise performance are shown to be possible when the devices are treated at high temperatures after the polysilicon deposition but prior to emitter implant. The reasons for this noise reduction are discussed with the aid of a simple model. The effects of scaling of the various physical and electrical parameters on the 1/f noise of polysilicon emitter transistors is investigated. The scaling of the vertical and lateral dimensions of the emitter is shown to have detrimental effect on the 1/f noise of the devices. This study also shows that the noise has a linear dependence on the operating current. The effects of rapid thermal annealing (RTA) on the 1/f noise performance is studied. The results suggest that this process may lead to a substantial increase in the low frequency noise of the devices, particularly in the small geometry devices. The probable cause of and a possible remedy to this effect are discussed. A technique for improving the 1/f noise characteristics by fluorination is investigated. The experimental results indicate a significant drop in the 1/f noise of RCA type devices, when small amounts of fluorine are implanted into the emitter. The mechanism by which this process leads to noise reduction is discussed. A theoretical model for the 1/f noise in polysilicon emitter BJTs is proposed which is based on the number fluctuation model. The model describes the noise behaviour of the transistor in terms of some physical and electrical parameters that are directly under manufacturers control.
University of Southampton
1991
Siabi-Shahrivar, Nasser
(1991)
A study of 1/f noise in polysilicon emitter transistors.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
This thesis describes the results of an experimental and theoretical study of 1/f noise in polysilicon emitter bipolar junction transistors. The physical origins of 1/f noise in these devices are investigated by studying devices with different emitter structures, such as RCA, HF, balled-oxide and epitaxially re-aligned devices. The experimental results show that when a thin and continuous layer of oxide is present at the polysilicon/silicon interface (i.e., RCA type devices), the 1/f noise of the device is substantially increased. The results also indicate that treating the devices in HF prior to polysilicon deposition, results in large improvements in the 1/f noise characteristics. Further improvements in the noise performance are shown to be possible when the devices are treated at high temperatures after the polysilicon deposition but prior to emitter implant. The reasons for this noise reduction are discussed with the aid of a simple model. The effects of scaling of the various physical and electrical parameters on the 1/f noise of polysilicon emitter transistors is investigated. The scaling of the vertical and lateral dimensions of the emitter is shown to have detrimental effect on the 1/f noise of the devices. This study also shows that the noise has a linear dependence on the operating current. The effects of rapid thermal annealing (RTA) on the 1/f noise performance is studied. The results suggest that this process may lead to a substantial increase in the low frequency noise of the devices, particularly in the small geometry devices. The probable cause of and a possible remedy to this effect are discussed. A technique for improving the 1/f noise characteristics by fluorination is investigated. The experimental results indicate a significant drop in the 1/f noise of RCA type devices, when small amounts of fluorine are implanted into the emitter. The mechanism by which this process leads to noise reduction is discussed. A theoretical model for the 1/f noise in polysilicon emitter BJTs is proposed which is based on the number fluctuation model. The model describes the noise behaviour of the transistor in terms of some physical and electrical parameters that are directly under manufacturers control.
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Published date: 1991
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Local EPrints ID: 460591
URI: http://eprints.soton.ac.uk/id/eprint/460591
PURE UUID: dbdf1d30-4a89-4a4c-abfa-8d3507d4a5a1
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Date deposited: 04 Jul 2022 18:25
Last modified: 04 Jul 2022 18:25
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Author:
Nasser Siabi-Shahrivar
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