The effects of base dopant outdiffusion and undoped Si/sub 1-x/Ge/sub x/ junction spacer layers in Si/Si/sub 1-x/Ge/sub x//Si heterojunction bipolar transistors

Prinz, E.J.; Garone, P.M.; Schwartz, Peter; Xiao, X.; Sturm, James C.

doi:10.1109/55.75698

Cited by 108 publications

(25 citation statements)

References 6 publications

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“…3 demonstrates the f T degradation for C-free HBTs with small overlaps. These devices show also a strong decrease in the product of V BE -driven Early voltage and current gain (β), a clear indication of B outdiffusion on the collector side of base [5]. The outdiffusion produces parasitic conduction band barriers, leading to a degradation of f T [6].…”

Section: Device Resultsmentioning

confidence: 99%

Emitter Scaling of Single-Polysilicon SiGe:C HBTs with Highly Doped Base Layers

Knoll

Heinemann²,

Ehwald³

et al. 2000

30th European Solid-State Device Research Conference

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We demonstrate that single-polysilicon SiGe:C heterojunction bipolar transistors with a very thin, highly doped SiGe layer can be scaled in the emitter width to 0.4 µm and in the emitter overlap to 0.2 µm without any indications of B outdiffusion from the SiGe:C base. Thus, transistors can be fabricated with excellent low-power performance, reaching an f max of 40 GHz at a collector current of 10 µA. We report also a reduction in the I B -driven Early voltage for devices with small overlap due to a perimeter component of the base current, originating from the external base, or the base contact region.

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Section: Device Resultsmentioning

confidence: 99%

Emitter Scaling of Single-Polysilicon SiGe:C HBTs with Highly Doped Base Layers

Knoll

Heinemann²,

Ehwald³

et al. 2000

30th European Solid-State Device Research Conference

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“…4 and 5 show anomalous behavior on both LOCOS and mesa devices when the undoped SiGe spacer is very thin. This suggests that the explanation for the anomalous behavior may be out-diffusion of boron from the SiGe base, which leads to the formation of parasitic energy barriers at the emitter/base and collector/base junctions [11]- [13], and consequently to a reduction of the collector current. The perimeter dependence of the slope seen in Fig.…”

Section: A Effect Of the Undoped Sige Spacer Thicknessmentioning

confidence: 99%

“…Boron out-diffusion from the base of a SiGe HBT can severely degrade the device performance due to the formation of parasitic energy barriers at the collector/base and emitter/base junctions [11]- [13]. Even very small amounts of out-diffusion (a few nanometers) from the SiGe base can dramatically degrade the collector current [14] and hence the current gain.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper, the analysis method described earlier [10], [11], [13] are further developed to take into account outdiffusion from the heavily doped bases of SiGe HBT's. This modified analysis method is then used to study how the major processing variables influence the device electrical characteristics when a SiGe epitaxial base is inserted into an existing CMOS-derived, single polysilicon, sef-aligned bipolar process.…”

Section: Introductionmentioning

confidence: 99%

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Determination of bandgap narrowing and parasitic energy barriers in SiGe HBT's integrated in a bipolar technology

Tron

Hashim

Ashburn

et al. 1997

IEEE Trans. Electron Devices

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Abstract-This paper describes a method for characterizing the bandgap narrowing and parasitic energy barrier in SiGe heterojunction bipolar transistors (HBT's), fabricated using a singlepolysilicon self-aligned bipolar process. From a comprehensive study of the temperature dependence of the collector current, the bandgap narrowing in the base due to germanium has been dissociated from that due to the heavy dopant concentration. The same approach has been used to characterize the height and width of parasitic energy barriers which appear when boron out-diffusion from the SiGe base is present. The method has been applied to SiGe heterojunction bipolar transistors fabricated using a single polysilicon, self aligned, bipolar process, as well as mesa transistors. The experimental results show that small geometry transistors have degraded collector currents due to boron out-diffusion around the perimeter of the emitter. This behavior has been explained by accelerated boron diffusion due to point defect generated during the extrinsic base implant. The values of undoped SiGe spacer thickness needed to suppress the parasitic energy barrier are described. Finally, high-frequency results are reported, which correlate the frequency transition to these parasitic energy barriers.

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“…The avalanche multiplication term, M, also plays a role in the high-current conduction during electrostatic-discharge events. With bandgap engineering, the SiGe transistor is designed so that the Ge concentration does not significantly penetrate into the Si collector region at the base-collector junction [12][13][14][15][16][17][18][19]25,26]. Germanium has a lower high electric field effective ionization threshold energy compared to Si (e.g., Ge is approximately 1 eV compared to 3.6 eV in Si), leading to a higher impact ionization rate.…”

Section: Device Physicsmentioning

confidence: 99%

Electrostatic discharge and high current pulse characterization of epitaxial-base silicon-germanium heterojunction bipolar transistors

Voldman

Juliano

Johnson³

et al.

2000 IEEE International Reliability Physics Symposium Proceedings. 38th Annual (Cat. No.00CH37059)

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This paper investigates high-current and electrostatic discharge (ESD) phenomenon in pseudomorphic epitaxial-base silicongermanium (SiGe) heterojunction bipolar transistors (HBT). Transmission line pulse (TLP) and ESD human body model (HBM) wafer-level reliability testing, failure analysis and simulation of SiGe HBT devices is completed for high-current characterization and evaluation of the ESD robustness of a BiCMOS SiGe technology.

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The effects of base dopant outdiffusion and undoped Si/sub 1-x/Ge/sub x/ junction spacer layers in Si/Si/sub 1-x/Ge/sub x//Si heterojunction bipolar transistors

Cited by 108 publications

References 6 publications

Emitter Scaling of Single-Polysilicon SiGe:C HBTs with Highly Doped Base Layers

Emitter Scaling of Single-Polysilicon SiGe:C HBTs with Highly Doped Base Layers

Determination of bandgap narrowing and parasitic energy barriers in SiGe HBT's integrated in a bipolar technology

Electrostatic discharge and high current pulse characterization of epitaxial-base silicon-germanium heterojunction bipolar transistors

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