Controlling transient enhanced diffusion effects in high-frequency Si0.7Ge0.3, heterojunction bipolar transistors with implanted emitters

L.K. Nanver* (Corresponding Author), C.C.G. Visser, A. van den Bogaard

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

A method is presented by which the implantation damage induced transient enhanced diffusion of boron and phosphorus is used to advantage to fabricate high-frequency Si0.7Ge0.3 heterojunction bipolar transistors with implanted phosphorus emitters. A device with 300 A basewidth, 7 kΩ/□ intrinsic base sheet resistance, and fT=44 GHz is demonstrated. The very low diffusivity of both boron and phosphorus in high Ge concentration SiGe during 700°C thermal annealing results in a self-alignment of the emitter-base junction to the Si/SiGe interface, giving high current gain with good reproducibility. Methods of counteracting the boron outdiffusion in the Si collector are considered. Rather than reducing this outdiffusion, results indicate that it can be better compensated for by introducing a narrow phosphorus doped peak, epitaxially grown on the collector side of the SiGe. The n doping of this peak, as is also the case for that of the emitter, barely penetrates the SiGe and the p-doped base is well preserved.

Original languageEnglish
Pages (from-to)1533-1537
Number of pages5
JournalJournal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures
Volume16
Issue number3
DOIs
Publication statusE-pub ahead of print/First online - 9 Jun 1998
Externally publishedYes

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