I. De Munari

Improved Pervasive Sensing With RFID: An Ultra-Low Power Baseband Processor for UHF Tags

Recently, radio frequency identification (RFID) systems have gained popularity in manufacturing units, inventory, and logistics, as they represent an inexpensive and reliable solution for automatic identification. Moreover, RFID transponders are expected to become a key element in the ubiquitous computing scenario. Tags will likely be used to collect sensors data, enabling noninvasive environment monitoring. Low-cost passive UHF transponders are expected to play a major role in this context, due to extended read range capabilities. Within a passive tag, power harvested from the field irradiated by the reader during the communication should operate both digital control circuitry and potential sensing devices. Exploiting ultra-low power tag circuitry would provide sensing sections with higher energy, thus improving measurement performance. In this paper, the design of a novel circuit is presented, which implements the baseband processor of a UHF-RFID tag in compliance with the ISO 18000-6B protocol. Regardless of protocol selection issues, several power saving strategies are devised, both at the system and circuit levels, suitable for passive transponder implementation. Near-threshold operation has been exploited to attain ultra-low power consumption while keeping fair performance. A set of standard cells has been designed, suitable for the power-limited specific application. The proposed solution has been successfully checked by means of a physical implementation on CMOS 0.18 mum technology. Test chips have been characterized in terms of voltage and frequency operating range and power consumption figure has been extensively analyzed. Measurement results fully support the selected design approach: the baseband processor dissipates only 440 nW average power when operated at 800 kHz and 0.6 V. This extremely-low power consumption enables high-performance ubiquitous computing.

Electromigration testing of integrated circuit interconnections

The electromigration phenomenon has been one of the most intriguing physical problems in the semiconductor device reliability. The models to explain the phenomenon are here revised, together with the influence of materials and their microstructure. The various measuring techniques are described, including the design of special test patterns, and statistical data analysis is briefly reviewed.

Electromigration in thin-films for microelectronics

Abstract Electromigration (EM) is one of the major concerns for the development of ULSI divices, but not all the aspects of the phenomenon are presently well understood. In this paper well established results and unsolved problems are reviewed and discussed. First, the physical model and in particular the influence of the mechanical stress on EM is considered. Then, the various techniques used to characterize electromigration are analyzed, making distinction between traditional techniques (median time to failure technique and resistometric methods) and more recently developed methods (high-resolution resistometric techniques and low-frequency noise measurement), also considering the fast techniques used for metallisation testing in the industrial environment. Finally, a section is devoted to the problem of test-structure and test-procedure standardisation in EM experiments.

Design of a 2 μW RFID baseband processor featuring an AES cryptography primitive

Cheap passive radio frequency identification (RFID) tags operating in ultra high frequency (UHF) bands are fostering innovation in several field such as building access control, goods tracking and supply chains management. RFID transponders can also be coupled to tiny sensors, enabling non invasive monitoring of environmental and personal parameters. To ensure the privacy of highly sensitive data, encryption and authentication capabilities should be embedded in RFID devices, in a fashion compatible with tight power budgets of wireless devices. In this contribution, a baseband-processor is introduced, which complies with ISO 18000-6C (EPC Class1 Gen2) protocol and integrates AES primitives aimed at secure data transmission. Performance of passive RFID devices is limited by the available power, harvested from the incoming radiation. Power-saving strategies are devised, both at the system and the circuit levels. A set of standard cells has been designed, suitable for near-threshold voltage operations. Physical implementation on CMOS 0.18 mum technology has been carried out and the chip has being fabricated.

An Assistive Home Automation and Monitoring System

A versatile, reliable and inexpensive home automation system is presented, suited for assisting and monitoring elderly and disabled people in home daily living. A smart interface module has been fabricated, which allows for straightforward integration of a wide variety of devices in a standard LAN. A pilot installation provides successfully HW and SW validation.

A comparison between normally and highly accelerated electromigration tests

Abstract Normally and highly accelerated electromigration tests on Al-Cu lines of different widths are compared. It is shown that the use of the Black equation gives different extrapolated results depending on the range of stress conditions considered. It is concluded that for extrapolations it is safe to use the Black equation only in the case of normally accelerated stress conditions (temperatures in the range 150–240°C and current densities between 1 and 2 MA/cm 2 ) and when the extracted value for the current density acceleration factor is 2.

A percolative approach to electromigration in metallic lines

We present a stochastic model which simulates electromigration damage in metallic interconnects by biased percolation of a random resistor network in the presence of degradation and recovery processes. The main features of experiments including Blacks law, times to failure distribution, current threshold for the onset of electromigration, etc are properly reproduced. Compositional effects showing up in early resistance changes measured on Al-0.5%Cu and Al-1%Si lines are also studied.

Test structures for electromigration evaluation in submicron technology

Electromigration tests have been performed on a number of test structures with different geometries and microstructures, highlighting the limits of each test structure in relation with the technologies employed in submicron interconnections. A new set of test structures based on the single level stripe, the multilevel Kelvin contact and via chain structures are then proposed to investigate electromigration in submicron technology devices. The new test structures are envisaged to overcome the problems which have previously been associated with conventional ASTM test structures. The use of a multifinger Babel Tower structure ensures that the microstructure of the end segment is consistent with the test stripe and the use of tungsten via plugs in multilevel systems eliminates the reservoir effect. These modifications will allow the reliability of the interconnections to be evaluated in a manner which is representative of actual ULSI device structures. As submicron lines are not the critical element of an IC metallisation, an additional set of test structures using a larger linewidth was designed to enable a comparison between bamboo and multigrain structures.

Power-Grid Load Balancing by Using Smart Home Appliances

Climate change is one of the greatest environmental, social and economic threats facing the planet, and can be mitigated by increasing the efficiency of the electric power generation and distribution system. Dynamic demand control is a low-cost technology that fosters better load balancing of the electricity grid, and thus enable savings on CO2 emissions at power plants. This paper discusses a practical and inexpensive solution for the implementation of dynamic demand control, based on a dedicated peripheral for a general-purpose microcontroller. Pre-production test of the peripheral has been carried out by emulating the actual microprocessor. Simulations have been carried out, to investigate actual efficacy of the proposed approach.

Are high resolution resistometric methods really useful for the early detection of electromigration damage

Abstract In this paper the use of High Resolution Resistometric Techniques for early detection of electromigration strength of AlCu/TiN/Ti stripes is analyzed. Two lots of 4 μm wide lines were tested obtaining largely different lifetimes. When comparing the early resistance changes, at a first sight a similar behaviour was detected in the two lots. However, a more accurate inspection of the resistance evolution revealed the presence of two distinct and subsequent stages. Significant differences were detected during the first stage only, lasting a few hours. If confirmed by extensive experiments, this result could open new perspectives for the early detection of the metal quality.