A. Schuppen

Enhanced SiGe heterojunction bipolar transistors with 160 GHz-f/sub max/

Double-mesa type SiGe heterojunction bipolar transistors (HBTs) have been improved by increasing the base Gummel number and by using a thin, highly doped launcher layer between the base and the collector. In addition, the contact resistance of the base contact has been reduced. Hence, it was possible to obtain a record maximum frequency of oscillation up to 160 GHz for a 2-emitter finger HBT in common emitter configuration.

CoSi2 and TiSi2 for SiSiGe heterodevices

Abstract Novel Si SiGe heterodevices with enhanced performance demand low thermal budget contact formation. CoSi2 and TiSi2 can meet this requirement. The investigation of self-aligned rapid thermal processes for the formation of CoSi2 (at 600–650 °C) and TiSi2 (at 650–750 °C) and their application to n-channel hetero field effect transistors and heterobipolar transistors (HBTs) is described and effects on the device performance are presented. Specific resistances of around 20 μΩ cm for CoSi2 and 17 μΩ cm for TiSi2 could be confirmed for the Si/SiGe heterosystem. Contact resistances on n+-phosphorous implanted layers below 6 μΩ cm2 have been derived from TLM structures. The silicide formation is severely affected by SiGe. Therefore the compound formation of CoSi2 in the Co Si and the Co Si 1 − x Ge x system has been investigated and compared as a function of annealing time in a temperature range from 400 to 600 °C. X-ray diffraction measurements on SiGe layers confirmed the formation of a mixture of CoSi and Co germanides with higher resistivity due to the interfacial reaction and the accumulation of Ge at the interface, which may act as a diffusion barrier. The choice of a Si cap above SiGe, whose thickness was properly adjusted to the material consumption correlated with the resulting silicide thickness, is proposed. The process and the performance of SiGe HBTs could be improved by the introduction of a Ti salicide process: base resistances yield values around 20 Ω (for an emitter area of 0.8 × 5 μm2). Nearly ideal Gummel plots confirm the advantage of using TiSi2.

Mesa and planar SiGe-HBTs on MBE-wafers

SiGe-HBTs have the potential for outstanding analog and digital or mixed-signal high frequency circuits widely based on standard Si technology. Here we review on MBE grown transistors and circuits. Processes and results of a research-like SiGe HBT and two possible production relevant HBT versions are presented. The high frequency results with fmax and fT up to 120 GHz and a minimum noise figure of 0.9 dB at 10 GHz demonstrate the advantage of using MBE samples with steep and high base doping and high germanium contents. A comparison to the concept of reported low doped, low germanium and triangular profiled SiGe base layers, realized by UHV-CVD, is given. In addition, some circuit demonstrators of SiGe-ICs will be presented.

High speed SiGe heterobipolar transistors

SiGe heterobipolar transistors are near the point of commercial availability. They will be inserted in mobile phones in the 0.9 to 2.4 GHz range and in wireless local area networks using the 2.4 to 5.8 GHz band. The advantage of SiGe HBTs is not only their excellent high frequency and noise performance with a maximum frequency of oscillation up to 120 GHz and 0.9 dB noise figure at 10 GHz, but the compatibility of SiGe to standard silicon technology. Fabrication processes and results of a research-like SiGe HBT and a possible production type HBT version are described. In addition, some circuit demonstrators for SiGe ICs will be presented.

Multi emitter finger SiGe-HBTs with f/sub max/ up to 120 GHz

Multi emitter finger silicon germanium heterojunction bipolar transistors (SiGe-HBTs) grown by MBE have been investigated by varying the collector design. No current crush effects have been observed for different transistor geometries. SiGe-HBTs with a 400 nm 2/spl times/10/sup 16/ cm/sup -3/ doped collector layers and 10 emitter fingers of 1 /spl mu/m/spl times/10 /spl mu/m exhibit a maximum oscillation frequency of 120 GHz and a power gain of 20 dB at 10 GHz. These are presently the highest values reported for silicon based transistors.<<ETX>>

SiGe devices and circuits: where are advantages over III/V ?

SiGe devices are just on an upswing due to their compatibility with existing silicon technologies. Outstanding SiGe ICs manufactured at high integration levels, high volume and low cost are envisaged. Concerning frequency they will fill the gap between standard Si and III/V. In some aspects like low-frequency and high-frequency noise, and low power consumption SiGe hetero bipolar transistors (HBTs) are advantageous over III/V-HBTs and approach the performance of some high electron mobility transistors (HEMTS), at least below 10 GHz. The paper reviews state of the art and potential of electronic SiGe heterodevices and tries a comparison to respective III/V devices.

Monolithic 26 GHz and 40 GHz VCOs with SiGe heterojunction bipolar transistor

Monolithically integrated 26 GHz and 40 GHz VCOs have been built with SiGe heterojunction bipolar transistors (HBT). The tuning range was more than 3 GHz, the output power behind an on-chip 10 dB-attenuator reached -13 dBm. The HBTs and the varactors were fabricated on the same high-resistivity substrate using the same MBE-grown layers. The transistors had an f/sub max/ of about 60 GHz and were operated in common-emitter series feedback configuration. Chip sizes including the microstrip resonators were 2/spl times/2.8 mm/sup 2/.

Low-Noise Amplifier for Mobile Communications using a Production Ready SiGe HBT Technology

A production ready SiGe HBT technology was used to realize a stage GHz low noise ampli er This ampli er exhibits a minimum noise gure of dB with up to dB associated gain at a supply voltage of V and a current of mA Input and output matching can be obtained by using bond wire inductances The third order input intercept point was observed at dBm

Assessment of intervalley f-scattering time constants in Si/SiGe heterostructures

The conduction band edge of silicon consists of six minima located in k-space along 〈100〉 directions. Transitions of electrons between perpendicular valleys are induced by so-called f-type intervalley scattering processes. In this work we have studied f-type intervalley scattering times using a specific SiSiGe bipolar transistor test structure were (low effective mass) electrons are selectively injected into four of the six valleys split energetically apart from the other two valleys by lattice mismatch strain. From the observed dependence of the collector current on the base width f-scattering time constants are deduced.