Michel Laurens

A high-speed low 1/f noise SiGe HBT technology using epitaxially-aligned polysilicon emitters

A 200 mm 0.35 /spl mu/m silicon-germanium heterojunction bipolar transistor (SiGe HBT) technology involving epitaxially-aligned polysilicon emitters is described. The devices are shown to combine the high speed performances typical for poly-Si emitter SiGe base devices (f/sub max/ up to 70 GHz) and the low 1/f noise properties of monocrystalline emitter structures (noise figure-of-merit KB as low as 7.2/spl times/10/sup -10/ /spl mu/m/sup 2/). Statistical current gain data are used to demonstrate the manufacturability of this innovative SiGe HBT technology.

Integration of SiGe heterojunction bipolar transistors in a 200 mm industrial BiCMOS technology

Abstract This paper reports the integration of SiGe heterojunction bipolar transistors (HBTs) in an industrial 200 mm, 0.5 μm BiCMOS process. The bipolar transistors of this technology have a single polysilicon quasi-self-aligned structure. The epitaxy of the emitter-base system, grown selectively in the bipolar active regions, was inserted into the standard process with minimum modification. During the epitaxy realized in an industrial, 200 mm, CVD module operating at reduced pressure, the MOS devices and the collector were protected by a thin oxide layer. No lithography step was added. The overall thermal budget was only slightly lowered. It was verified that the performance of the MOS device was not degraded by these modifications. The results presented here were obtained on HBTs with a gradual Ge content (from 10% on the collector side to 5% on the emitter side) and a collector doped at 10 17 cm −3 . The nominal HBT (0.6×1.2 μm 2 emitter area) shows a maximum gain of 140, early voltage of 60 V, BV CE0 of 3.6 V and maximum f T of 29 GHz. This work is a first step towards an optimized HBT-CMOS technology.

100GHz SiGe:C HBTs using non selective base epitaxy

We report the fabrication and electrical characterization of high performance 0.25μm SiGe HBTs incorporating a carbon-doped base grown using non selective epitaxy. A transit frequency fT of 97GHz and a maximum oscillation frequency fmax of 94GHz have been obtained together with well balanced static parameters. These are the highest frequency performances reported to date for non selective epitaxy SiGe HBTs, including carbon-doped

High frequency mismatch characterization on 170GHz HBT NPN bipolar device

This paper describes a high frequency mismatch approach on BJT able to reach Ft=170GHz. All obtained results are complementary and all well linked with the mismatch extract from DC measurement and in good agreement with the model parameters. In order to extract these results, a new test structure and associated parameter extraction tool have been developed.

Low frequency 1/f noise characterization of advanced CMOS-compatible bipolar junction transistors for technology evaluation

The knowledge of low frequency noise characteristics of microelectronics devices is known to be indispensable for evaluation of their performance in analogue circuits. However, potential of noise techniques for transistor diagnostics and assessment of processes involved in their fabrication has not yet been fully recognized. Using bipolar junction transistors, BJTs, we demonstrate how the measurements of power spectral density, PSD, of base current, Ib, fluctuations, expressed as Sib = Kf Ib /f γ + 2qIb, where Kf and Af are standard SPICE noise parameters, can be used for this purpose. Our data are restricted to the low frequency, 1/f, region, with γ ≈1 and Af ≈2.

Impact of emitter resistance mismatch on base and collector current matching in bipolar transistors

Bipolar transistor matching is characterized at medium and high current levels using an HF test structure. We demonstrate the predominant impact of emitter resistance mismatch on base and collector current matching at high current. To this end, we simulate base and collector mismatch thanks to the experimental values of emitter access resistance and its variations. The results of these simulations are successfully compared to the experimental data.

A 70-GHz-fT double-polysilicon SiGe HBT using a non selective epitaxial growth

This paper describes a high performance heterojunction bipolar transistor using a low complexity double polysilicon architecture. Non selective Si/SiGe epitaxy was selected for the base formation, allowing higher manufacturability than for a selective process. Low spread in statistical results confirms very good control and reproducibility of the Si/SiGe stack deposition and epitaxially aligned emitter fabrication. Static and high frequency measurements analysis shows excellent set of electrical parameters: 70-GHz-f T and 90-GHz-f max have been measured for 2.5 BV CE0 devices.

Evaluation of transport properties of ozonized poly/mono interfaces in polysilicon emitter bipolar transistors

Abstract Temperature-dependent electrical measurements have been performed to determine hole and electron transport properties across the poly/mono interface in polysilicon emitter bipolar transistors. A tunneling probability has been extracted, and the results are correlated with noise parameters.

New test structures for extraction of base sheet resistance in BiCMOS technology

For process monitoring and device modeling, a new method to determine the different components of the base resistance of bipolar transistors has been developed. Dual base test structures have been improved to extract the sheet resistance value of each of these components using dc measurements. This method is applied to a state-of-art double poly ST BiCMOS technology, and results are discussed.

Suppression of boron transient-enhanced diffusion in SiGe HBTs by a buried carbon layer

The experiments described in this paper show that base broadening effects due to extrinsic base implantation in SiGe HBTs can be suppressed by introducing a buried carbon layer under the SiGe/Si base prior to epitaxy. They also demonstrate that SiGe HBTs with excellent static (/spl beta//spl times/V/sub AF//spl sim/10/sup 4/ V) and dynamic (f/sub T/B/spl times/BV/sub CEO//spl sim/200 GHz/spl times/V) characteristics can be fabricated using an epitaxially aligned in-situ-doped polysilicon emitter and an appropriately designed SiGe/Si base profile.