The benefits of fluorine in pnp polysilicon emitter bipolar transistors

Moiseiwitsch, N.E.; Ashburn, P.

doi:10.1109/16.293355

Cited by 19 publications

(8 citation statements)

References 25 publications

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“…Since [20], this decrease in indicates that the F decreases the resistance of the interfacial oxide. Hence, these noise results can be regarded as evidence that F promotes interfacial oxide breakup [15] and hence reduces noise, as has been reported previously [17]. It should also be noted that the decrease of explains the increase of both the collector current and the base current observed in the F implanted devices at high base-emitter voltages (Table I).…”

Section: A Input Noise Voltagesupporting

confidence: 82%

“…The effect of the F implant on the base current could then be explained by passivation of the interface states by the F, as has been reported previously [15]. This passivation is likely to have occurred by F diffusion through the polysilicon and deposited oxide where the polysilicon overlaps onto the deposited oxide [22].…”

Section: B Base Current Noisementioning

confidence: 55%

“…As a result, four different types of transistor were created, namely: 1) no F, no BF ; 2) F, no BF ; 3) BF , no F; and 4) F BF . Fluorine has been shown to give passivation of trapping states at the polysilicon/silicon interface and promotes interfacial oxide breakup [15] and hence would be expected to influence the noise. The polysilicon emitter contact was then implanted with , 70 keV As and patterned, as shown in Fig.…”

Section: Methodsmentioning

confidence: 99%

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The influence of BF/sub 2/ and F implants on the 1/f noise in SiGe HBTs with a self-aligned link base

Lukyanchikova

Garbar

Petrichuk

et al. 2001

IEEE Trans. Electron Devices

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A study is made of 1 noise in SiGe heterojunction bipolar transistors (HBTs) fabricated using selective growth (SEG) of the Si collector and nonselective growth (NSEG) of the SiGe base and Si emitter cap. The transistors incorporate a self-aligned link base formed by BF 2 implantation into the field oxide below the p + polysilicon extrinsic base. The influence of this BF 2 implant on the 1 noise is compared with that of a F implant into the polysilicon emitter. Increased base current noise S IB and base current are seen in transistors annealed at 975 C, compared with transistors annealed at 950 or 900 C. At a constant collector current, both the BF 2 and F implants reduce S IB , whereas at a constant base current, only the BF 2 implant reduces S IB. This result indicates that the BF 2 implant decreases the intensity of the base current noise source whereas the F implant decreases the base current. The proposed explanation for the increased 1 noise is degradation of the surface oxide by viscous flow at 975 C under the influence of stress introduced during selective Si epitaxy. The influence of the BF 2 implant on the noise is explained by the relief of the stress and hence the prevention of viscous oxide flow.

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Section: A Input Noise Voltagesupporting

confidence: 82%

Section: B Base Current Noisementioning

confidence: 55%

Section: Methodsmentioning

confidence: 99%

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The influence of BF/sub 2/ and F implants on the 1/f noise in SiGe HBTs with a self-aligned link base

Lukyanchikova

Garbar

Petrichuk

et al. 2001

IEEE Trans. Electron Devices

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“…9,14 Fluorine has also been shown to give higher gains 15 and improved base current idealities 15 due to the passivation of dangling bonds at the oxide/silicon interface. Hence the incorporation of fluorine into the polysilicon can have major beneficial effects on both the materials and the devices, so it is important to understand the role played by the fluorine.…”

Section: Introductionmentioning

confidence: 99%

“…It was deduced that the faster regrowth with fluorine present occurred because of a faster breakup of the interfacial oxide and the suggested reason for this was the formation of Si-O-F complexes which could result in a weakening of the bonding structure of the interfacial oxide. 15 It has also been suggested that fluorine increases boron diffusion down the grain boundaries of the polysilicon. 17 Chen et al 18 showed that, for polysilicon layers implanted with BF 2 ϩ and annealed at 850-1100°C, a broad band of small defects was present in the upper part of the layer and a narrow band of small defects at the interface.…”

Section: Introductionmentioning

confidence: 99%

Behavior and effects of fluorine in annealed n+ polycrystalline silicon layers on silicon wafers

Marsh

Moiseiwitsch

Booker

et al. 2000

Journal of Applied Physics

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A comprehensive study is made of the behavior and effects of fluorine in n ϩ -polysilicon layers. The polysilicon is deposited in a conventional low pressure chemical vapor deposition furnace on ͑100͒ silicon wafers, implanted with 1ϫ10 16 cm Ϫ2 F ϩ and 1ϫ10 16 cm Ϫ2 As ϩ and annealed at 850, 950, 1015, and 1065°C. Sheet resistance, transmission electron microscopy ͑TEM͒, and secondary ion mass spectroscopy are used to obtain quantitative data for the breakup of the interfacial oxide, the epitaxial regrowth of the polysilicon layer, and the fluorine and arsenic distributions. The fluorine significantly increases both the initial oxide breakup ͑ϳ8ϫ͒ and the initial polysilicon regrowth. It also produces inclusions in the layer which can affect the subsequent polysilicon regrowth and the arsenic distributions. Three regrowth stages and two regrowth mechanisms are distinguished and interpreted, and a value of ϳ6ϫ10 Ϫ11 cm 2 s Ϫ1 is deduced for the effective diffusivity of fluorine in polysilicon at 950°C. The amounts of regrowth determined by TEM are compared with the corresponding changes in sheet resistance. The thermal budgets required to produce polysilicon layer regrowths of 1% and 50%, important for the performance of polysilicon emitter bipolar transistors, are given. All the thermal budgets are lower when fluorine is present.

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Kamins

1998

Polycrystalline Silicon for Integrated Circuits and Displays

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The benefits of fluorine in pnp polysilicon emitter bipolar transistors

Cited by 19 publications

References 25 publications

The influence of BF/sub 2/ and F implants on the 1/f noise in SiGe HBTs with a self-aligned link base

The influence of BF/sub 2/ and F implants on the 1/f noise in SiGe HBTs with a self-aligned link base

Behavior and effects of fluorine in annealed n+ polycrystalline silicon layers on silicon wafers

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