Presentation on theme: "Adrian Ionescu Nanolab, EPFL Switzerland 1. Prove that energy efficient nanolectronics is a must for the future… … and NEMS is a potential key enabling."— Presentation transcript:
Power crisis in nanoelectronics Leakage power dominates in advanced technology nodes. V T scaling saturated by 60mV/dec limit, voltage scaling slowed. Power Density (W/cm 2 ) 1E-05 1E-04 1E-03 1E-02 1E-01 1E+00 1E+01 1E+02 1E+03 0.010.11 Gate Length (μm) Passive Power Density Active Power Density Source: B. Meyerson (IBM) Semico Conf., January 2004 4
What matters: energy / computed bit scaling systemability system level metrics prevail over device level Integrated approach for energy/bit at system level: Switch Memory Interconnects Architecture Embedded Software 5
A fundamental issue? 7 n less than (kT/q)ln10 # injection in the channel Tunnel FETs Impact Ionization MOS m less than 1 active gate devices: NEM relay or NEMFET negative capacitance
Nano-Electro-Mechanical (NEM) Devices NEM switch NEM memory NEM resonators 8
9 as a multi-state logic, with the logic states dictated by a spatial configuration of movable objects as vibrational modes of mechanical elements, based upon waves. as a sensed or transduced signal operation.
11 Advantages: - zero Ioff (zero static power). - abrupt transition between off and on states. (Unwanted?) feature of NEM switch: - hysteresis due to different values of pull-in, V pi (off-on transition) and pull-out, V po (off-on transition) voltages. Pull-in voltage:
12 For low cost & high performance, post-CMOS integration is desirable. Thermal process budget is constrained for MEMS fabrication: surface micromachining is low T Si Substrate foundry CMOS MEMS Source: T.J. King.
14 Source: V. Pott, T.J. King, UC Berkeley. Nice but large (10s micrometer) size! Scalable?
15 W. W. Jang et al, Appl. Phys. Lett., 92(10), 103110, 2008. Nice, small size! Ioff excellent But voltage large: > 10V Scalable?
16 CMOS to real logic mappping Relay technology F. Chen et al, ICCAD 2008. 100x less energy per half-adder
17 Energy / useful bit = transmit energy + transmitted energy + receive energy = signal processing + front-end = signal processing + front-end + sleep (scan) mode 10 pJ @ 2m ~1000 less than SoA PHY, MAC, NETW Role of MEMS/NEMS in low power communications? Role of MEMS/NEMS in low power communications?
18 B. Halg, "On a micro-electro-mechanical nonvolatile memory cell", IEEE Transactions on Electron Devices, Vol. 37, Iss. 10, 1990. thin micromachined bridge elastically deformed: two stable mechanical states : 0 and 1 MOS process: Si0 2 layer bridge covered by a 2nm thin Cr state of the bridge changed using electrostatic forces read out by sensing the capacitance Size: ~hundreds m 2 Actuation voltage: > 40V
19 Y. Tsuchiya, K. Takai, N. Momo, T. Nagami, H. Mizuta, S. Oda, "Nanoelectromechanical nonvolatile memory device incorporating nanocrystalline Si dots", Journal of Applied Physics, 100, 2006.
20 Nano- E lectro- M echanical NV memory –RWL as a top electrode –BL as a movable mechanical beam: information stored as BL position –ONO stack for charge storage –WWL as a lower electrode W.Y. Choi; H. Kam; D. Lee, J. Lai, T.-J. King Liu, "Compact Nano-Electro- Mechanical Non-Volatile Memory (NEMory) for 3D Integration", Technical Digest of IEEE International Electron Devices Meeting, IEDM 2007.
21 NEMory cell operation is based on the hysteretic behavior of a mechanical gap-closing actuator. Charge in the ONO layer is used to shift the hysteresis curves by V offset, to achieve bistability at 0 V (V BL-WWL V BL - V WWL ), thus enabling non-volatile storage.
22 J.W. Han, Jae-Hyuk Ahn, Min-Wu Kim, Jun-Bo Yoon, and Yang-Kyu Choi, "Monolithic Integration of NEMS-CMOS with a Fin Flip-flop Actuated Channel Transistor (FinFACT)", IEDM 2009. Principle: laterally movable (suspended) silicon FIN, bistable & sensed by transistor current flow.
23 - Depending on design (width) can be used both as NV (ROM) or SRAM. - Trade-off between the endurance and retention.
24 NEM switched capacitor structure based on vertically aligned MW CNTs - Capacit. of CNT NEM DRAM cell (diameter=60 nm; length=1.6 m; SiNx,=40 nm): value of 0.59 fF with available potential of 2.4 mV for bit line sensing in a conventional DRAM design. -15 fF and 60–80 mV (Gbit DRAM) possible by the integration of high-k (not shown) - voltages > 14V J.E. Jang et al, "Nanoscale memory cell based on a nanoelectromechanical switched capacitor", Nature Nanotechnology, Vol. 3, Jan. 2008, pp. 26-30.
26 Adrian Ionescu, GRC 201226 Probably the most promising family of RF M/NEMS. Embedding full equivalent circuit functions (RLC) with very high-Q and voltage tuning (possible replacement of quartz). Applications: oscillators, mixing, filtering, sensing. Passive MEMS resonator Resonant body transistor
27 Frequency, mass, Q mass & force detection nm SOI-CMOS technology integration density, complexity Nanowire RB-FET: 40 nm x 40 nm x 2 um Fully-depleted RB-FET: 0.5 µm x 0.25 µm x 10 µm 400 nm NW-FET body
28 Tunable operation point: Trade-off: gain versus power. Experiment: resonance from strong to weak inversion. nW static power consumption in weak-inversion (P DC < P AC ). S. T. Bartsch, A.M. Ionescu, IEDM 2010.
29 Double-gate (in-plane) VB-FET resonator: transistor detection improves output signal by more than +30dB. D. Grogg et al, IEDM 2008. Capacitive Transistor
30 Transistor-based homodyne / heterodyne mixing. Mixing coupled to mechanical motion. Signal-to-background improvement. Applications: VHF mixer-filter, closed-loop configurations. I mix ~ g m S.T.Bartsch et al, ACS Nano 2011. Cc-Beam: 0.15 x 0.2 x 3 µm 3 f 0 =78 MHz, Q=1100
Energy efficient devices: a must for the future! Challenges: 34 NEMS Relays scaling of: gaps & size operation voltage reliability of contacts & packaging dedicated IC design Resonators analog/RF & sensing
NEM memory: exploit the. electromechanical hysteresis of movable structures by a gap closing Storage layer: specific purpose for shifting the hysteresis (NEMory, Odas memory, SG-FET)! excellent co-integration with silicon CMOS. Low temperature processing, BEOL (3D-) integration possible, low cost. Low voltage operation possible, limits ~1V Program/erase & read times: <10ns energy efficiency: less than 10-16 J/bit in NEMory & SBM. Trade-off between endurance & retention in FIN-FACT. Robust in high temperature and radiation environments. CNT-based memory: immature Promising for embedded memory applications 35