Microscale Thermal of Electronic Systems

Ken Goodson

Thermosciences Division Department

Stanford University Key Points 1. Self Heating of Transistors and Interconnects

IBM

silicon 2. Nanothermal Devices for Information Technology

15 µm IBM Zurich / Stanford Solid- state EO pump

3. Microscale Technologies for Heat and Power Management Microprocessor Thermal Challenges ESD Metal Heating Texas Instruments Metal 1 (AlCu)

W-plug

Silicon Dioxide Thermal TiN damage

Siemens 0.2 µm n+ Silicon Diffusion Region Novel Materials 1 µm Novel Geometries

IBM

Strained Silicon / Si Ge UC Berkeley/AMD Nanotransistors

Strained-Si channel Gate Gate Gate Tbody

Source Drain Source Drain Source Drain Relaxed SiGe SiO Graded SiGe 2

Lch Si substrate Si substrate Classic Bulk FET Strained-Si FET Thin Body SOI

Drain Gate Tbody Gate Source Drain

Gate Source

Double-Gate SOI FinFET (Purdue, IBM) (UC Berkeley, AMD, IBM) Transistor Electrothermal Physics

ApproximateHigh Impact Electric of Device Field Scaling on Peak Phonon Temperatures Hot Electrons 225 nm (Energy E) E > 50 meV τ ~ 0.1ps Power Q’( IBM E < 50 meV τ ~ 0.5ps OpticalOptical Phonons Phonons

τ ~ 10 ps µ W/ lattice wave Acoustic Phonons electron Acoustic Phonons µ m) λ (K) Increase T ∆ field intense electron-phonon Λ scattering d phonon E = hω Channelto Package Length L (nm) dopant phonon atom Pop, Banerjee, Dutton, Goodson, Proc. IEDM 2001 Material boundary with roughness η Transistor Simulation Regime Map

Atomistic Nanotransistor Regime

BTE with electrons phonons , Wave models u 0) p, J 00 ru (2 ~5 nm ~100 nm rd n e so MFP Sv d r BTE or oo da G um ~5 nm ~1 nm Monte Carlo aj λ , M rk ai ) o L 95 ) w a 9 0 Research ch tk (1 99 5) u hu (1 99 needs for m c r (1 a ) hu W 94 S ch the future Diffusion 9 vi Lattice (1 o ) an 70 ) 2) p 19 83 6 A ( 5) 9 ) s 19 er 8 (1 88 s ( ja 19 i 9 re n k ( on (1 g , to te ni ) b i ro ta at e a 86 o tt p at ) tr lo ar 9 ac he D 5 S B c (1 J c In 99 Isothermal ac n is 1 B a F ( ud m R ro st nd BTE Lu & BTE Models Moments Monte Carlo Monte Carlo Drift Diffusion with Quantum with Electrons Full Quantum Electron Drift & Phonon Generation at 40kV/cm

Thesis work of Eric Pop, 2003

Phonon Emission

• Monte Carlo, 300 electrons at 300 K • Electric Field starts at 0.5 ps

• Eavg jumps from 39 meV to 290 meV Interconnect Thermal Managementρ d Student: Sungjun Im. Sponsor – MARCO ~ j2 d ILD η N1.7 Peak ∆T MET MET k 220100 ILD 50 nm

C) 209209 °°CC C] o 200 o 35 nm GlobalGlobal WiresWires 180 70 nm 50 160 100 nm

140 130 nm

Temperature [ Temperature 180 nm

Temperature Rise ( Temperature 1200

0246810Temperature Contour Plot Distance from Substrate [µm] (50 nm technology node) The temperature rise in interconnects is small now, but compounding trends in the ITRS roadmap lead to a tremendous increase at the 70 nm node beyond low-k dielectric materials increasing current densities and aspect ratios increasing number of interconnect layers Nanoscale Thermal Data Storage IBM Zurich: Vettiger, Binnig Stanford: King, Kenny, Goodson. See King et al., Applied Physics Letters 78, 1300 (2001)

Data Writing Data Reading I Ibias bias Ibias

∆T ~ 300 K “0” “1” ∆T ~ 5 K ∆T reduced

100 nm Cantilever Array Stanford University Micro- and NanoMechanics Zurich Research Laboratory Microrocessor Thermal Management

Heat Sinks, Heat Pipes, ASICs Vapor Chambers ~1 cm3 ~ 102 cm3

RAM ~10-1 cm3 Power Delivery ~1 cm3 Video ~10-1 cm3 ~10-1 cm3 HOTSPOTS

Microprocessor heat sinks are 3000 They crowd away power delivery times larger and heavier than the chip components, ASICs, RAM, and Video Interdisciplinary Grand Challenge: Integrated Power Delivery & Heat Removal Groups of Goodson, Kenny, Santiago, Saraswat, Stanford Mechanical Engineering Groups of Thompson & Troxel, MIT Materials and

Thermofluidic Mixed-Signal Power Module (Sponsors: SRC/MARCO & DARPA) Integrated MEMS Photonic I/O RF Sensing Electrical Fluidic I/O Connections Mixed Signal Chip Fluidic Cooling

Thermofluidic Module with Solid-State Pump (Sponsors: Intel & DARPA) Free I/O targeted, on-demand Integrated EO Surface Fluid Electrical microchannel cooling Pump/controller Connections Mixed Signal Chip ElectroOsmotic Microchannel Cooler Sponsors: DARPA, Intel, AMD, Apple. Trans CPMT (2002). Best Paper SemiTherm 2001 PIs: Goodson, Santiago, Kenny, Stanford ME 2001: 30 W Demo, 1 cm2 (Intel) 2002: Laptop Demo 2002: 100 W Demo, 1 cm2 (Intel) 2002: Apple Dual Processor Demo 2002: 150 W Demo, 4 cm2 (Intel) 2003: AMD Demo

ElectroOsmotic Pump

Silicon High-Pressure dioxide Heat Rejector + wall Liquid Pumping - ~ 50 nm

+ Charge + + double-layer + + + Charge Double Layer

Microchannel Heat Sink EO Pump Channels Micro Heat Sink In silicon Thermal Pyrex seal attach Stanford/Intel 100 W Demo Si chip EO Pump Flowrate ~ 20 ml/min ElectroOsmotic Pumps With groups of Santiago and Kenny, Stanford Mechanical Engineering Sponsor: SRC/MARCO, DARPA Idealized pore channel: Glass or fused-silica capillary wall Free- standing + EOF - pump

+ 1 cm Charge + + + ++ + double-layer ++++++ ++ + Deprotonated silanol groups εζE dp (a 2 − r 2 ) u(r) = − µ dx µ

εζ VA 32εζ Q = ∆p = V •Very high volume to flowrate ratio max µ l max d 2 •Stanford pump performance (Feb 2002)

3 Pmax ~ 2 atm, Qmax ~ 40 ml/min, Vol. ~ 2 cm 2370 Charleston Mountain View, CA 94043 www.cooligy.com

Cooligy develops thermal • Founded in 2001 by Stanford Profs. management components based on Ken Goodson, Tom Kenny, Juan electro-osmotic pumps and novel Santiago, Mechanical Engineering microscale heat exchangers • 24 employees (Feb 2003) with engineering expertise including chemical, mechanical, packaging, Heat Rejector thermal, & fluidic specialties

• Experienced management and directors drawn from Intel, Dell, Corning, Silicon Light Machines.

• Focussing on reliability demonstration, product EO Pump implementation, collaboration with Micro Heat Sink computer manufacturers Concluding Remarks

• The next decade of IC research & development will bring solutions to “secondary” challenges associated with Moore’s Law, such as power delivery, heat removal, and package integration.

• IC thermal management problems will have lengthscales spanning six orders of magnitude, from 10 nm in nanotransistors to more than 10 cm at the package level.

• Novel materials and geometries are increasing micro/nanoscale on-chip thermal resistances, leading to hotspots in metallization and interconnects.

• Circuit design focuses computation on the chip, yielding mm-scale hotspots that dramatically increase the thermal resistance from the chip to the package. Goodson Microscale Heat Transfer Group Thermosciences Division, Mechanical Engineering Department, Stanford

Current Students and Post-Docs (AY 2002/2003) Dachen Chu (Physics) Monikka Mann (ME) Xuejiao Hu (ME) Sanjiv Sinha (ME) Sungjun Im () Evelyn Wang (ME) Kevin Ness (ME) Ankur Jain (ME) Jae-Mo Koo (ME) Yue Liang (ME) Dr. Linan Jiang Angie McConnell (ME) Dr. Abdullahel Bari Eric Pop (Electrical Engineering) Dr. Samuel Graham (Visitor from SNL)

Alumni (1999-2002) Prof. Mehdi Asheghi Carnegie Mellon University (ME) Prof. Dan Fletcher UC Berkeley (Bioengineering) Prof. Bill King Georgia Tech (ME) Prof. Katsuo Kurabayashi University of Michigan (ME) Prof. Sungtaek Ju UCLA (ME) – with IBM until Fall 2003 Prof. Kaustav Banerjee UC Santa Barbara (EE) Dr. Uma Srinivasan Xerox Dr. Per Sverdrup Intel Dr. Peng Zhou Cooligy Dr. Maxat Touzelbaev AMD