Online proceedings - EDA Publishing Association

The overall objective of the NANOPACK project is todevelop new thermal interface technologies for low thermalresistance by employing nano-modified surfaces andmaterials along with methods to characterize and simulatethem with respect to thermal, electrical and reliability-relatedproperties. Three parallel approaches will be pursued toimprove thermal and electrical performance: enhancement ofbulk conductivity of filled systems, reduction of bondlinethickness, and optimization of nanoscale thermal andelectrical contact surfaces (see Fig. 1). To tackle the overallproject purpose, four major technical objectives are targeted:• To develop new interface technologies for low thermaland electrical resistance and discover new high-densityintegration technologies;• To develop new characterisation methods and tools forthin and highly conductive interface layers;• To understand heat transfer on a micro/ nano scale thanksto simulative and nano-analytical methods;• To build optimal demonstrators with respect to thermal,electrical and reliability-related properties to createimpact in several industries.III. METHODOLOGY AND WORK PLANIn order to successfully achieve the project goals andenable the development of leading thermal management andinterconnect technologies at the horizon of 2010, anintegrated methodology has been set-up and the project hasbeen organized into 6 main technical work packages whichaddress research issues: materials and process development,thermal, electrical and mechanical characterization,supported by world class modeling and simulations. Severaldemonstrators will be designed to validate the adequacy ofthe technologies with applications such as microprocessors,automotive and aerospace high power electronics and highpower radio-frequency switches.Fig. 2. NANOPACK Work PlanA. Materials DevelopmentWithin the project, high performance nano-TIMs will bedeveloped and manufactured. This can be accomplished by(i) finding out desirable nano-TIM compositions wherenano-fillers and matrix may well be incorporated; (ii) byoptimizing dispersing technologies to generate minimumthermal barriers between nano-fillers and matrix and to24-26 September 2008, Rome, Italyachieve a maximum thermal conductivity; (iii) bysynthesizing nano-structured materials such as nanoparticles,nanotubes, nanofibrils packed nanoparticles and nanograssand (iv) by developing nano-porous resist templates forelectroplated nano-structures. Thermal grease, thermalconductive adhesive, thermal conductive phase changematerials and electrically conductive adhesive will bestudied.B. Process Development and OptimizationThese activities aim at establishing new manufacture andintegration process which enables more efficient heatremoval in modern integrated circuits and microsystems.Several parallel routes will be studied. A novel techniquebased on micromachined hierarchical nested channels(HNC) will be developed to modify the thermal interfaces,enabling the control of particle stacking during bondlineassembly with highly particle-filled materials. High thermalconductive interconnects based on carbon nanotubes (CNT)and gold nano structures, which have much higher thermalconductivity than conventional materials, will be developed.These techniques also provide a possibility to build ultra finepitch interconnection and thus allow very high integrationdensity of microsystems.C. Fabrication of Test StructuresThe role of this work is to explore and manufacture teststructures to facilitate the in-situ measurement of thin layersof very high thermal conductivity materials. Additional teststructures will also be realised in order to investigate theelectrical properties of microscale particle stacks forelectrical interconnects in power electronics die attach. Bothsteady state and transient measurement methods will be usedin the consortium.D. Metrology and CharacterizationThis work is focused on the characterization of theinterface materials developed in the project along with theirprocess dependence in thermal, electrical and thermomechanicalproperties. Test specimens will be measured interms of thermal resistance, thermal conductivity/diffusivity,interface resistance and electrical conductivity, on acontinuum or sub-micron scale, in static or transient modes,each of which has certain advantages with respect tosensitivity to a specific physical property, resolution orapplicability. Failure of interfaces and crack propagationwill also be studied thanks to advanced in-situ thermomechanicalexperiments.E. Modeling and SimulationsState-of-the-art simulation techniques will be developed tobetter understand heat transfer at the nano and micro scalesin thin films and dense particle systems. Both analytictechniques and IBM Blue Gene super-computer assistedmolecular dynamics simulations will be used to explorephonon properties in nano scale systems. In addition to morescientific studies, traditional tools such as finite elementanalysis for mechanical structures will be incorporated fordesign of demonstrator devices and failure analysis.©EDA Publishing/THERMINIC 2008 154ISBN: 978-2-35500-008-9