Process Variability and Electrostatic Analysis of Molecular QCA

Molecular quantum-dot cellular automata (mQCA) is an emerging paradigm for nanoscale computation. Its revolutionary features are the expected operating frequencies (THz), the high device densities, the noncryogenic working temperature, and, above all, the limited power densities. The main drawback of this technology is a consequence of one of its very main advantages, that is, the extremely small size of a single molecule. Device prototyping and the fabrication of a simple circuit are limited by lack of control in the technological process [Pulimeno et al. 2013a]. Moreover, high defectivity might strongly impact the correct behavior of mQCA devices. Another challenging point is the lack of a solid method for analyzing and simulating mQCA behavior and performance, either in ideal or defective conditions. Our contribution in this article is threefold: (i) We identify a methodology based on both ab-initio simulations and post-processing of data for analyzing an mQCA system adopting an electronic point of view (we baptized this method as “MoSQuiTo”); (ii) we assess the performance of an mQCA device (in this case, a bis- ferrocene molecule) working in nonideal conditions, using as a reference the information on fabrication-critical issues and on the possible defects that we are obtaining while conducting our own ongoing experiments on mQCA: (iii) we determine and assess the electrostatic energy stored in a bis-ferrocene molecule both in an oxidized and reduced form. Results presented here consist of quantitative information for an mQCA device working in manifold driving conditions and subjected to defects. This information is given in terms of: (a) output voltage; (b) safe operating area (SOA); (c) electrostatic energy; and (d) relation between SOA and energy, that is, possible energy reduction subject to reliability and functionality constraints. The whole analysis is a first fundamental step toward the study of a complex mQCA circuit. It gives important suggestions on possible improvements of the technological processes. Moreover, it starts an interesting assessment on the energy of an mQCA, one of the most promising features of this technology.

[1]  Mariagrazia Graziano,et al.  Asynchronous Solutions for Nanomagnetic Logic Circuits , 2011, JETC.

[2]  Massimo Ruo Roch,et al.  Feedbacks in QCA: A Quantitative Approach , 2015, IEEE Transactions on Very Large Scale Integration (VLSI) Systems.

[3]  C. Lent,et al.  Molecular quantum cellular automata cells. Electric field driven switching of a silicon surface bound array of vertically oriented two-dot molecular quantum cellular automata. , 2003, Journal of the American Chemical Society.

[4]  Graham A. Jullien,et al.  Simulation of random cell displacements in QCA , 2007, JETC.

[5]  M. Zamboni,et al.  An NCL-HDL Snake-Clock-Based Magnetic QCA Architecture , 2011, IEEE Transactions on Nanotechnology.

[6]  Steven M. Nowick,et al.  ACM Journal on Emerging Technologies in Computing Systems , 2010, TODE.

[7]  F. Lombardi,et al.  Testing of quantum cellular automata , 2004, IEEE Transactions on Nanotechnology.

[8]  Gianluca Piccinini,et al.  Charge distribution in a molecular QCA wire based on bis-ferrocene molecules , 2013, 2013 IEEE/ACM International Symposium on Nanoscale Architectures (NANOARCH).

[9]  Gianluca Piccinini,et al.  Understanding a Bisferrocene Molecular QCA Wire , 2014, Field-Coupled Nanocomputing.

[10]  Li Cai,et al.  Reliability and Performance Evaluation of QCA Devices With Rotation Cell Defect , 2012, IEEE Transactions on Nanotechnology.

[11]  Gianluca Piccinini,et al.  A new validation method for modeling nanogap fabrication by electromigration, based on the Resistance–Voltage (R–V) curve analysis , 2012 .

[12]  Craig S. Lent,et al.  Power dissipation in clocking wires for clocked molecular quantum-dot cellular automata , 2010 .

[13]  Gianluca Piccinini,et al.  Bis-Ferrocene Molecular QCA Wire: Ab Initio Simulations of Fabrication Driven Fault Tolerance , 2013, IEEE Transactions on Nanotechnology.

[14]  Paolo Lugli,et al.  Planar nanogap electrodes by direct nanotransfer printing. , 2009, Small.

[15]  D. Demarchi,et al.  Molecular QCA: A write-in system based on electric fields , 2011, The 4th IEEE International NanoElectronics Conference.

[16]  P. Kollman,et al.  An approach to computing electrostatic charges for molecules , 1984 .

[17]  Gianluca Piccinini,et al.  UDSM Trends Comparison: From Technology Roadmap to UltraSparc Niagara2 , 2012, IEEE Transactions on Very Large Scale Integration (VLSI) Systems.

[18]  Azzurra Pulimeno Molecular Quantum-dot Cellular Automata (QCA): Characterization of the bis-ferrocene molecule as a QCA device , 2013 .

[19]  Mariagrazia Graziano,et al.  Towards a molecular QCA wire: Simulation of write-in and read-out systems , 2012 .

[20]  Z. Li,et al.  Molecular QCA cells. 1. Structure and functionalization of an unsymmetrical dinuclear mixed-valence complex for surface binding. , 2003, Inorganic chemistry.

[21]  M. Vacca,et al.  Asynchronous Solutions for Nano-Magnetic Logic Circuits , 2015 .

[22]  Fabrizio Lombardi,et al.  Modeling QCA defects at molecular-level in combinational circuits , 2005, 20th IEEE International Symposium on Defect and Fault Tolerance in VLSI Systems (DFT'05).

[23]  Massimo Ruo Roch,et al.  Quantum Dot Cellular Automata Check Node Implementation for LDPC Decoders , 2013, IEEE Transactions on Nanotechnology.

[24]  Craig S. Lent,et al.  Molecular quantum-dot cellular automata , 2003, 2006 IEEE Workshop on Signal Processing Systems Design and Implementation.

[25]  Massimo Marcaccio,et al.  Toward Quantum-dot Cellular Automata units: thiolated-carbazole linked bisferrocenes. , 2012, Nanoscale.

[26]  Gianluca Piccinini,et al.  Molecular transistor circuits: From device model to circuit simulation , 2014, 2014 IEEE/ACM International Symposium on Nanoscale Architectures (NANOARCH).

[27]  Wolfgang Porod,et al.  Quantum cellular automata , 1994 .

[28]  M. Zamboni,et al.  Majority Voter Full Characterization for Nanomagnet Logic Circuits , 2012, IEEE Transactions on Nanotechnology.

[29]  Mariagrazia Graziano,et al.  FFT implementation using QCA , 2012, 2012 19th IEEE International Conference on Electronics, Circuits, and Systems (ICECS 2012).

[30]  Franco Cacialli,et al.  Thermochemical nanopatterning of organic semiconductors. , 2009, Nature nanotechnology.

[31]  Mariagrazia Graziano,et al.  A Hardware Viewpoint on Biosequence Analysis: What’s Next? , 2013, JETC.

[32]  Wolfgang Porod,et al.  Investigation of shape-dependent switching of coupled nanomagnets , 2003 .

[33]  Jieying Jiao,et al.  Building blocks for the molecular expression of quantum cellular automata. Isolation and characterization of a covalently bonded square array of two ferrocenium and two ferrocene complexes. , 2003, Journal of the American Chemical Society.

[34]  Gianluca Piccinini,et al.  NanoCube: A Low-Cost, Modular, and High-Performance Embedded System for Adaptive Fabrication and Characterization of Nanogaps , 2014, IEEE Transactions on Nanotechnology.

[35]  Mariagrazia Graziano,et al.  Magnetic dipolar coupling and collective effects for binary information codification in cost-effective logic devices , 2012 .

[36]  Gianluca Piccinini,et al.  An electromigration and thermal model of power wires for a priori high-level reliability prediction , 2004, IEEE Transactions on Very Large Scale Integration (VLSI) Systems.