Cyril Fellous

230-GHz self-aligned SiGeC HBT for optical and millimeter-wave applications

This paper describes a 230-GHz self-aligned SiGeC heterojunction bipolar transistor developed for a 90-nm BiCMOS technology. The technical choices such as the selective epitaxial growth of the base and the use of an arsenic-doped monocrystalline emitter are presented and discussed with respect to BiCMOS performance objectives and integration constraints. DC and high-frequency device performances at room and cryogenic temperatures are given. HICUM model agreement with the measurements is also discussed. Finally, building blocks with state-of-the-art performances for a CMOS compatible technology are presented: A ring oscillator with a minimum stage delay of 4.4 ps and a 40-GHz low-noise amplifier with a noise figure of 3.9 dB and an associated gain of 9.2 dB were fabricated.

High performance 0.25 /spl mu/m SiGe and SiGe:C HBTs using non selective epitaxy

A robust 0.25 /spl mu/m double-poly SiGe HBT structure using non selective epitaxy has been developed. The device features 70/90 GHz f/sub T//f/sub max/ with pure SiGe base in 0.25 /spl mu/m BiCMOS technology. Performances up to 120/100 GHz f/sub T//f/sub max/ are demonstrated for SiGe:C base transistors.

230 GHz self-aligned SiGeC HBT for 90 nm BiCMOS technology

This paper describes a 230 GHz self-aligned SiGeC HBT featuring a selective epitaxial base and an arsenic-doped monocrystalline emitter. These technical choices are presented and discussed with respect to BiCMOS performance objectives and integration constraints.

Selective SiGeC epitaxy by RTCVD for high performance self-aligned HBT

Selective SiGeC epitaxy is desirable for forming the base of self aligned HBTs. Carbon, incorporated into substitutional sites (C/sub s/), should suppress boron outdiffusion in the base. We show that C/sub s/ incorporation is decreased as temperature or total C concentration is increased, leading to defects in the epitaxy and degradation of the base current. Nevertheless, we were able to grow, selectively, high quality SiGeC films with a C dose high enough to block boron diffusion. This is confirmed by the comparison of static and dynamic results between a C-free and a C-doped SiGe HBT Finally, a state of the art 175 GHz ft/180 GHz f/sub MAX/ HBT with a selective epitaxial SiGeC base is presented.

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.

Modeling dopant diffusion in SiGe and SiGeC layers

Following the developement of a unified diffusion model valid for all usual dopants in SiGe layers [1], considering the effect of carbone diffusion on point defects concentrations extends the application of our model to strained SiGeC layers. Using a new SIMS methodology, the study of As intrinsic diffusion in SiGe and SiGeC layers is performed, at low concentration and under equilibrium annealing conditions. Arsenic enhanced diffusion in fully-strained SiGe and SiGeC layers on Si substrates was successfully compared to the unified diffusion model.

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.