J.W. Slotboom

Measurements of bandgap narrowing in Si bipolar transistors

Abstract Theory predicts appreciable bandgap narrowing in silicon for impurity concentrations greater than about 1017 cm−3. This effect influences strongly the electrical behaviour of silicon devices, particularly the minority carrier charge storage and the minority carrier current flow in heavily doped regions. The few experimental data known are from optical absorption measurements on uniformly doped silicon samples. New experiments in order to determine the bandgap in silicon are described here. The bipolar transistor itself is used as the vehicle for measuring the bandgap in the base. Results giving the bandgap narrowing (ΔVg0) as a function of the impurity concentration (N) in the base (in the range of 4.1015–2.5 1019 cm−3) are discussed. The experimental values of ΔVg0 as a function of N can be fitted by: δV g0 = V 1 ln N N 0 + ln 2 N N 0 +C where V1, N0 and C are constants. It is also shown how the effective intrinsic carrier concentration (nie) is related with the bandgap narrowing (ΔVg0).

Unified apparent bandgap narrowing in n- and p-type silicon

Abstract In the literature, separate models exist for the apparent bandgap narrowing in n - and p -type Si, yielding a smaller bandgap narrowing in n -type than in p -type Si. Using a recently-published model, which describes both the majority and the minority carrier mobility, we have recalculated the apparent bandgap narrowing from the measurements upon which the bandgap narrowing models mentioned above are based. The results of this new interpretation show no difference in apparent bandgap narrowing in n - and p -type Si. A function describing the unified bandgap narrowing is presented.

The pn-product in silicon

Optical absorption measurements [1] and theoretical calculations [2–9] have shown that the bandgap in silicon is not only temperature-dependent but is also influenced by the impurity concentration at higher values. Recent electrical measurements [10] of the pn-product in the base region of bipolar transistors made it possible to derive the bandgap narrowing quantitatively as a function of the impurity concentration. n nIn this paper it will be shown that theoretical calculation of the pn-product as a function of temperature and impurity concentration can be approximated by the following relationship: pn = nie2(N, T) = CT3 exp (− qVgo(N)/kT) for temperatures between about 280 and 450°K. n nMoreover the calculated values for C and Vgo(N) show surprisingly good quantitative agreement with the values derived from the above mentioned pn-measurements [10].

A back-wafer contacted silicon-on-glass integrated bipolar process. Part II. A novel analysis of thermal breakdown

Analytical expressions for the electrothermal parameters governing thermal instability in bipolar transistors, i.e., thermal resistance R/sub TH/, critical temperature T/sub crit/ and critical current J/sub C,crit/, are established and verified by measurements on silicon-on-glass bipolar NPNs. A minimum junction temperature increase above ambient due to selfheating that can cause thermal breakdown is identified and verified to be as low as 10-20/spl deg/C. The influence of internal and external series resistances and the thermal resistance explicitly included in the expressions for T/sub crit/ and J/sub C,crit/ becomes clear. The use of the derived expressions for determining the safe operating area of a device and for extracting the thermal resistance is demonstrated.

A back-wafer contacted silicon-on-glass integrated bipolar process. Part I. The conflict electrical versus thermal isolation

A novel silicon-on-glass integrated bipolar technology is presented. The transfer to glass is performed by gluing and subsequent removal of the bulk silicon to a buried oxide layer. Low-ohmic collector contacts are processed on the back-wafer by implantation and dopant activation by excimer laser annealing. The improved electrical isolation with reduced collector-base capacitance, collector resistance and substrate capacitance, also provide an extremely good thermal isolation. The devices are electrothermally characterized in relationship to different heat-spreader designs by electrical measurement and nematic liquid crystal imaging. Accurate values of the temperature at thermal breakdown and thermal resistance are extracted from current-controlled Gummel plot measurements.

Bandgap narrowing in silicon bipolar transistors

Martinelli [1] recently reported on measurements of theI-Vcharacteristics of silicon bipolar transistors as a function of temperature. His conclusion was that there was no evidence of bandgap narrowing in the transistors. Our experiments [2] on n-p-n transistors indicate that the bandgap does narrow for impurity concentrations aboveN = 10^{17}cm-3. The reason for this discrepancy follows from Martinellis assumption that the temperature dependence of the minority carrier mobility in the p-type base is given by T-2.6, independently of the impurity concentration, which is not justified by our measurements.

QUBiC4X: An f/sub T//f/sub max/ = 130/140GHz SiGe:C-BiCMOS manufacturing technology witg elite passives for emerging microwave applications

P. Deixler, A. Rodriguez, W. De Boer, H. Sun, R Colclaser, D. Bower, N. Bell, A. Yao’, RBrock’, Y. Bouttement.’, G.A.M. Hurkx4>, L.F. TiemeijeS, J.C.J. Paassehens4”, H.G.A Huizing”,D.M.H. Hartskeer14, P. Agamal’, P.H.C Magnee’, E. Aksen’ and J.W. Slotboom6 Philips Semiconductors, 2070 Route 52, P.O. Box 1279, Hopewell Junction, NY 12533, USA ’Philips RF Device Modeling Group, San Jose, USA; ’ Philips RF Modeling Group, Caen, France ‘ Philips Natlab, Eindboven, The Netherlands; ’ Philips Research Leuven, Leuven, Belgium; ‘Univ. Delft, Netherlands Email: Peter.Deixler@philips.com, Phone: ++1 845 902 1586 Abstract QUBiC4X is a cost-effective ultra-high-speed SiGe:C RF-BiCMOS technology for emerging microwave applications with NPN fr/f,, up to l30/140GHz, enhanced RF-oriented 2.5V CMOS, SiGe:C Power Amplifiers with 88% power-added efficiency, distinguished substrate isolation, full suite of elite high-density passives, 5 metal layers and an advanced design flow.

QUBiC4G: a f/sub T//f/sub max/ = 70/100 GHz 0.25 /spl mu/m low power SiGe-BiCMOS production technology with high quality passives for 12.5 Gb/s optical networking and emerging wireless applications up to 20 GHz

QUBiC4G is a robust very low-power SiGe RF-BiCMOS technology for emerging wireless and optical networking with NPN f/sub T//f/sub max/ up to 70/100 GHz and BV/sub ceo/ = 2.7 V, excellent substrate isolation, 0.25 /spl mu/m CMOS, full suite of high quality passives, 5 metal layers and an advanced design flow. We present a 12.5 Gb/s optical networking crosspoint switch and a low-noise 20 GHz LC-VCO.

On the optimization of SiGe-base bipolar transistors

Extensive computer simulations of NPN SiGe-base bipolar transistors were performed to examine the effect of the Ge profile in the electrical characteristics. It is shown that extra charge storage in the emitter-base (E-B) junction, caused by the Ge profile, affects the device performance considerably. In addition, it is shown that an abrupt Ge profile in the middle of the base region is optimal for a given critical layer thickness of approximately 600A.

Microwave modelling and measurement of the self- and mutual inductance of coupled bondwires

The modelling and measurement of the self- and mutual inductance of bonding wires up to 10 GHz is considered. Differences less than 10% between calculated and measured self inductances are reported. The influence of various parameters on the inductance is considered.