GROUPE : MICROELEC SI


Welcome to the Silicon Microelectronics Group at IEMN

The group gathers researchers, staff and students working in the fields of Electronic Circuit Design and Micro and Nanotechnologies for Flexible Electronics and Energy.

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Integrated Circuit Design for Communication Systems

The integrated circuit design activity within the Silicon Microelectronics group deals with the study, design and demonstration of novel architectures for RF and millimeterwave (mmW) communication systems. The philosophy of the carried research lies in the leveraging of existing technologies (advanced CMOS technologies at nodes from 90nm down to 28nm) to propose innovative architectures with breakthroughs at the system, block or transistor level. In these technologies, as digital processing comes almost for free compared to analog functions, we tried to integrate digital functionalities in traditional transceivers, by either correcting for analog non-idealities or replacing analog blocks. Our main objective is to enable future communication systems with reduced power consumption, higher configurability and higher throughput, together with a higher level of integration.

Digital transmitter architectures for RF applications

  • High-speed delta-sigma modulators
  • Digital-to-RF converters
  • Wideband multi-rate digital PA.
  • High data rate mmW communications

Direct digital-to-mmW tranmitters

  • WiFi/WiGig compatible transmitter based on delta-sigma and DRFC concepts
  • Subsampling-based receivers
  • Beamforming architectures
  • Tunable baseband filtering

Continuous-time digital signal processing

 

Non-Conventional Technology for CMOS and Enhanced Functionalities

Our activities embrace innovative processes and devices from crude semiconductors (enhancing CMOS core) to enhanced functional CMOS based on non-conventionnal nanotechnology. Research topics follow the strategies of “More-Moore” with Metallic (Schottky) source/drain MOSFET) and “More-thant-Moore” with VLS growth of Si blades for smart BEOL and Nanowires for gas detection. Recently new perspectives have openned with the rise of High-performance (HF) flexible electronics and non-conventional thermoelectrics.

High performance SOI-CMOS (HF) flexible electronics

Very high frequency, mechanically flexible and performance stable integrated electronics based on SOI-CMOS transfer bonding on plastic substrates.

The ability to realize flexible circuits integrating sensing, signal processing, and communicating capabilities is of central importance for the development of numerous nomadic applications requiring foldable, stretchable and large area electronics. A large number of these applications currently rely on organic electronics, or integrate high mobility active films on plastic foils to provide higher performance. A key challenge is however the combination of high electrical performance (i.e. millimeter wave, low noise electronics), with the mechanical flexibility required to adapt to curvilinear surfaces, in addition to high stability of these electrical performance upon deformation.

In this work, a solution has been developed, based on thinning and transfer onto plastic foil of high frequency (HF) CMOS devices initially patterned on conventional silicon-on-insulator (SOI) wafers.

This process enables the fabrication of high performance electronics on plastic, with n-MOSFETs featuring characteristic frequencies fT/fmax as high as 150/160GHz in addition to low noise potentialities: NFmin/Ga of 0.57/17.8dB.

Secondly, by locating the neutral plane of the flexible system in its active layer, the relative variation of these high frequency figures-of-merit can be limited to 5% even after aggressive bending, demonstrating mechanical flexibility, high electrical performance and stability upon deformation.

Unconventional Principles of ThermoElectric Generation

This activity aims at exploring two unorthodox tracks towards a drastic reduction of heat transfer and a significant increase of thermoelectric conversion. It is funded in the frame of an European Research Council  Starting Grant (n°338179) awarded to J.-F. Robillard in 2013.

Follow this project on : https://www.researchgate.net/project/Unconventional-Principles-of-ThermoElectric-Generation

Abstract

The performance of thermoelectric generation has long since been limited by the fact that it depends on hardly tunable intrinsic materials properties. At the heart of this problem lies a trade-off between sufficient Seebeck coefficient, good electrical properties and suitably low thermal conductivity. The two last being closely related by the ambivalent role of electrons in the conduction of both electrical and thermal currents. Current research focuses on materials composition and structural properties in order to improve this trade-off also known as the figure of merit (zT). Recently, evidences aroused that nanoscale structuration (nanowires, quantum dots, thin-films) can improve zT by means of electron and/or phonon confinement. The aim of this project is to tackle the intrinsic reasons for this low efficiency and bring TE conversion to efficiencies above 10% by exploring two unconventional and complementary approaches:

Phononic Engineering Conversion consists of modulating thermal properties by means of a periodic, precisely designed, arrangement of inclusions on a length scale that compares to phonon means free path. This process is unlocked by state of the art lithography techniques. In its principles, phononic engineering offers an opportunity to tailor the phonon density of states as well as to artificially introduce thermal anisotropy in a semiconductor membrane. Suitable converter architecture is proposed that takes advantage of conductivity reduction and anisotropy to guide and converter heat flow. This approach is fully compatible with standard silicon technologies and is potentially applicable to conformable converters.

The Micro Thermionic Conversion relies on low work function materials and micron scale vacuum gaps to collect a thermally activated current across a virtually zero heat conduction device. This approach, though more risky, envisions devices with equivalent zT around 10 which is far above what can be expected from solid state conversion.

People

Emmanuel Dubois, Yves Deblock, François Vaurette

Stanislav Didenko, Tianqi Zhu

Valentina Giorgis, Fikre Gebreyohannes, Pascale Diener

Valeria Lacatena, Maciej Haras, François Morini

Metallic (Shottky) source-drain MOSFETs device technology

VLS growth of Si blades for smart BEOL

Silicon nanowires for high gain and fast detection of warfare agent