tech - Semiconductor Cooling Techniques

Semiconductor Cooling Techniques -Sohan Purohit Department of Electrical and Computer Engineering, University of Rochester Sohan Purohit, University of Rochester 1 Introduction  High Performance-High Power go hand in hand. Cooling and Power Delivery become important issues. In the near future   • • Total Chip power rises by ~ 60 % Heat Flux-Expected to double Sohan Purohit, University of Rochester 2 Projection of Processor Power Sohan Purohit, University of Rochester 3 Nottingham Inversion Cooling  Based on Internal Field Emission Uses Composite-Thin-Film Device + Heat Sink Uses Wide Band Gap materials-prevents tunneling of electrons   Sohan Purohit, University of Rochester 4 How it Works  Injected Electrons are transported Quasi Ballistically. Heat carried by electrons is decoupled from the lattice.   Cooling due to removal of hot electrons by tunnelingAlso called NOTTINGHAM INVERSION COOLING Sohan Purohit, University of Rochester 5 Cooling by Luminescence up-conversion      Interaction of a system with radiation can lead to cooling. Physicists report observation of phonon-mediated upconversion of luminescence in GaAs. Sample is resonantly pumped with light energy. Temperature drops as much as 10% of initial temperature are reported. Localised lattice cooling takes place-Important for the semiconductor industry. Sohan Purohit, University of Rochester 6  Cooling is due to a strong electron phonon coupling at the localised spot-somehow disconnected from the rest of the lattice sub system . This coupling still remains somewhat a mystery. Results –Qualitative. Possibility of Localized cooling however has been demonstrated.    Sohan Purohit, University of Rochester 7 Electronic Cooling by Quasiparticle Tunneling  A very much unexplored approach. Replace metal by a heavily doped semiconductor, in the cooling device. From the Practical and Technological side-Best choice.    Efficient Integration in today’s Semiconductor industry. Sohan Purohit, University of Rochester 8 How it Works  Weak Electron Phonon coupling at low temperatures.  Weak EP coupling-Key Issue in the Cooling Process. Silicon films-Strong candidates for low-temperature on-chip cooling applications.  Sohan Purohit, University of Rochester 9 Recent Developments  Semiconductor Cooling has received much attention in the past few years. Novel Cooling techniques coming up. Promising new Techniques   • • Micro-pump Cooling Ion Pump Cooling. Sohan Purohit, University of Rochester 10 Conclusions   As on-chip power increases-Cooling issues become important problems to deal with. Novel cooling techniques discussed here are a direct off shoot of this.  “Either we let our fate determine its own course or we proactively attack the power issues”-Christian Belady, Hewlett Packard Company Sohan Purohit, University of Rochester 11