110-GHz f/sub T/ silicon bipolar transistors implemented using fluorine implantation for boron diffusion suppression

Kham, M.N.; Mubarek, H.A.W. El; Bonar, J. M.; Ashburn, P.; Ward, Peter; Fiore, Ludovica; Petralia, R.; Alemanni, C.; Messina, Alberto

doi:10.1109/ted.2005.864368

Cited by 3 publications

(3 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The above fluorine diffusion suppression technique has been applied to a double polysilicon silicon bipolar tech- nology in collaboration with ST Microelectronics, Catania, Italy [15]. Figure 11 shows the effect of a 150 keV, 5 • 10 14 cm −2 F + implant on the f T of a silicon bipolar transistor and it can be seen that fluorine increases the maximum f T from 46 to 60 GHz.…”

Section: Application Of Fluorine Diffusion Suppression Technique In B...mentioning

confidence: 99%

“…Scanning tunnelling microscopy was used to show that the improvement was due to a reduction of the overlap length, for example from 13 to 7 nm in 40 nm gate length p-channel MOSFETs. Finally, Kham et al [15] applied fluorine implantation to silicon bipolar technology to reduce the diffusion of the base and as a result have delivered a silicon bipolar transistor with a record f T of 110 GHz. In this paper, we review the properties and benefits of fluorine in silicon and silicon-germanium devices.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Properties and benefits of fluorine in silicon and silicon-germanium devices

Ashbur,

A. W. El Mubarek

2007

JTIT

View full text Add to dashboard Cite

This paper reviews the behaviour of fluorine in silicon and silicon-germanium devices. Fluorine is shown to have many beneficial effects in polysilicon emitter bipolar transistors, including higher values of gain, lower emitter resistance, lower 1/f noise and more ideal base characteristics. These results are explained by passivation of trapping states at the polysilicon/silicon interface and accelerated break-up of the interfacial oxide layer. Fluorine is also shown to be extremely effective at suppressing the diffusion of boron, completely suppressing boron transient enhanced diffusion and significantly reducing boron thermal diffusion. The boron thermal diffusion suppression correlates with the appearance of a fluorine peak on the SIMS profile at approximately half the projected range of the fluorine implant, which is attributed to vacancy- fluorine clusters. When applied to bipolar technology, fluorine implantation leads to a record fT of 110 GHz in a silicon bipolar transistor.

show abstract

Section: Application Of Fluorine Diffusion Suppression Technique In B...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Properties and benefits of fluorine in silicon and silicon-germanium devices

Ashbur,

A. W. El Mubarek

2007

JTIT

View full text Add to dashboard Cite

show abstract

“…11 The recent application of fluorine implantation to silicon bipolar technology has delivered a record f T of 110 GHz. 12 Although the effect of fluorine is well documented in the literature, its mechanism in suppressing boron diffusion is still under research. Initial work 5 suggested that the suppression of boron diffusion by fluorine was due to chemical effect of the fluorine.…”

Section: Introductionmentioning

confidence: 99%

Reduced boron diffusion under interstitial injection in fluorine implanted silicon

Kham

Maťko

Chenevier

et al. 2007

Journal of Applied Physics

Self Cite

View full text Add to dashboard Cite

Point defect injection studies are performed to investigate how fluorine implantation influences the diffusion of boron marker layers in both the vacancy-rich and interstitial-rich regions of the fluorine damage profile. A 185 keV, 2.3ϫ 10 15 cm −2 F + implant is made into silicon samples containing multiple boron marker layers and rapid thermal annealing is performed at 1000°C for times of 15-120 s. The boron and fluorine profiles are characterized by secondary ion mass spectroscopy and the defect structures by transmission electron microscopy ͑TEM͒. Fluorine implanted samples surprisingly show less boron diffusion under interstitial injection than those under inert anneal. This effect is particularly noticeable for boron marker layers located in the interstitial-rich region of the fluorine damage profile and for short anneal times ͑15 s͒. TEM images show a band of dislocation loops around the range of the fluorine implant and the density of dislocation loops is lower under interstitial injection than under inert anneal. It is proposed that interstitial injection accelerates the evolution of interstitial defects into dislocation loops, thereby giving transient enhanced boron diffusion over a shorter period of time. The effect of the fluorine implant on boron diffusion is found to be the opposite for boron marker layers in the interstitial-rich and vacancy-rich regions of the fluorine damage profile. For marker layers in the interstitial-rich region of the fluorine damage profile, the boron diffusion coefficient decreases with anneal time, as is typically seen for transient enhanced diffusion. The boron diffusion under interstitial injection is enhanced by the fluorine implant at short anneal times but suppressed at longer anneal times. It is proposed that this behavior is due to trapping of interstitials at the dislocation loops introduced by the fluorine implant. For boron marker layers in the vacancy-rich region of the fluorine damage profile, suppression of boron diffusion is seen for short anneals and then increased diffusion after a critical time, which is longer for inert anneal than interstitial injection. This behavior is explained by the annealing of vacancy-fluorine clusters, which anneal quicker under interstitial injection because the injected interstitials annihilate vacancies in the clusters.

show abstract