Focus on DotFive

http://www.dotfive.eu/index.php?id=18

The concept of the DOTFIVE project stems from the competitive race existing in semiconductor research to achieve individual devices and integrated circuits with higher operating speed allowing realization of new applications in new regions of the electromagnetic spectrum.

Applications in the emerging high-frequency (h.f.) markets more and more use SiGe components for cost reasons. Current state-of-the-art research and development is taking place primarily in data communication and radar systems at 24, 60, and 77 GHz [Floy06, Kata07, Haji05]. For instance, IBM has just demonstrated that its state-of-the-art SiGe HBT technology has the potential to play a major role in high-volume consumer electronic markets by proving the feasibility of 2-Gbps uncompressed HDTV transmission over a 60-GHz SiGe HBT radio link [Kata07, Pfei06a, Floy06].

The main objective of the DOTFIVE project is to demonstrate the realization of SiGe Heterojunction Bipolar Transistors (HBTs) operating at a maximum frequency close to 0.5 THz (500 GHz) at room temperature, and evaluate the achievable performance of integrated mmWave circuits using those HBTs. Further important objectives are: 0 To identify the most important effects and to incorporate an adequate description in a compact model. To develop new parameter extraction methods and to provide a unified set of test structures. To provide clear guidelines on high-frequency characterization, de-embedding methods and test pad design.

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The main drawbacks in existing designs, which operate typically at frequencies up to a third of the transit frequency fT, are the necessary high bias currents leading to a power dissipation of several watts per radar chip and a limited achievable noise figure (NF) in each building block. The former disadvantage results in additional cooling effort, which implies costly packaging and mounting procedures. The latter directly influences the overall performance, as the total signal-to-noise ratio (SNR) in homodyne systems is directly limited by the NF of the (active) mixer. Thus, technologies with higher fT can directly lead to improved automotive radar systems with higher performance at lower power consumption, which increases road safety and energy budget. With an increased fT completely new and highly integrated microwave sensor systems are feasible.

However, until recently, this spectral region has resisted attempts to broadly harness its potential for everyday applications. This led to the expression THz gap, loosely describing the lack of adequate technologies to effectively bridge this transition region between microwaves and optics, both readily accessible via well developed electronic and laser-based approaches. THz technology is an emerging field which has demonstrated a wide-ranging potential. Extensive research in the last years has identified many attractive application areas and has paved the technological path towards broadly usable THz systems. THz technology is currently in a pivotal phase and will soon be in a position to radically expand our analytic capabilities via its intrinsic benefits. In this context, DOTFIVE is planned to establish the basis for fully integrated cost efficient electronic THz solutions.

                           Figure 1: Illustration of some exemplary applications of Terahertz radiation.
P. de Maagt, P. Haring Bolivar and C. Mann, Terahertz science, engineering and systems-from space to earth applications, Encyclopedia of RF and Microwave Engineering, Ed. by K. Chang, pp. 5175-5194 (John Wiley & Sons, Inc., 2005) ISBN 0-471-27053-

The scientific aspects of the DOTFIVE project are tackled by the work packages (WPs) 1 to 5 during a period of 36 months.

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WP1 is dedicated to “TCAD & physics-based predictive modeling” using Technology Computer Aided Design (TCAD) tools, which allow the simulation of processing steps and electrical characteristics of devices.
WP1 will support continuously the technology development in WP2 and WP3 by, e.g., assessing the achievable performance limits, identifying the critical limitations, and exploring new device concepts and architectures. WP1 will investigate the ultimate limits of SiGe HBT technology in terms of device performance, transport limits, quantum effects, and safe operation area limitations.
Partners involved: UN, ST SA, IMEC, IMS, BU, GWT

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WP2 is dedicated to “evolutionary SiGe HBT technology”. The work in WP2 will be based on state-of-the-art double-polysilicon self-aligned HBT architecture with selectively deposited SiGeC base. The objective of WP2 is to improve the performance of this technology towards the demanding DOTFIVE targets, such as 500 GHz maximum oscillation frequency and 2.5 ps gate delay.
Partners involved:ST SA, ST SAS, IFX

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WP3 is dedicated to “advanced and novel SiGe HBT process modules and architectures”. Next to the evolutionary scaling of self-aligned selective epitaxial base HBTs in WP2, advanced and possibly revolutionary process modules are further developed and characterized in WP3. Focus is on the development of device architectures that have shown promising initial results.
Partners involved:IMEC, IHP

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WP4 is dedicated to “compact modeling and device characterization”. This work package is in charge of setting up the methodology to accurately characterize transistors and to provide models that are valid and usable for circuit design all the way to 500 GHz.
Partners involved:ST SA, IFX, TUD, UN, UPS, XMOD, GWT

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WP5 is dedicated to “application and technology benchmarking”. The objective of the work package is to direct the advanced process development and modeling (WP1,2,3) towards the next-generation of mmWave and THz applications through benchmarking and verifiable prototyping.
Partners involved:IFX, IMS, UoS, JKU, UoW

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WP6 is dedicated to the training and dissemination of the DOTFIVE results.
Partners involved:IMEC, ALMA, IFX, IHP, IMS, XMOD

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WP7 is dedicated to the management of the project
Partners involved:ST SA, ALMA