On the Use of Static Temperature Measurements as Process Variation Observable

In this paper we present the use of static temperature measurements as process variation observable. Contrary to previously published thermal testing methods, the proposed methodology does not need an excitation signal, thus reducing test cost and improving built-in capabilities of thermal monitoring. The feasibility of the technique and a complete test methodology is presented using a narrowband LNA as example. Finally, a complete electro-thermal co-simulation test bench between the LNA and a differential temperature sensor embedded in the same silicon die is presented in order to validate the results. Results prove that RF figures of merit can be extracted from DC temperature measurements done without loading or exciting the RF circuit under test.     

Dynamic Surface Temperature Measurements in ICs

Measuring techniques of the die surface temperature in integrated circuits are reported as very appropriate for failure analysis, for thermal characterization, and for testing modern devices. The paper is arranged as a survey of techniques oriented towards measuring the temperature dynamics of the circuit surface and presenting and discussing both the merits and drawbacks of each technique with regard to the accuracy, reliability and efficiency of the measurements. Two methods are presented in detail: laser probing methods, based on interferometry and thermoreflectance, and embedded CMOS circuit sensors. For these techniques, the physical principles, the state of the art in figures of merit and some application examples are presented.     

Nonlinearity characterization of temperature sensing systems for integrated circuit testing by intermodulation products monitoring

This work presents an alternative characterization strategy to quantify the nonlinear behavior of temperature sensing systems. The proposed approach relies on measuring the temperature under thermal sinusoidal steady state and observing the intermodulation products that are generated within the sensing system itself due to its nonlinear temperature-output voltage characteristics. From such intermodulation products, second-order interception points can be calculated as a figure of merit of the measuring system nonlinear behavior. In this scenario, the present work first shows a theoretical analysis. Second, it reports the experimental results obtained with three thermal sensing techniques used in integrated circuits.     

Differential Thermal Testing: An Approach to its Feasibility

Testing techniques based on the functional behaviour, the propagation delay and the levels of quiescent current have been used with great success for the last two decade technologies. However, the efficiency of such techniques is dubious for future technologies, characterised by huge mixed-mode complex circuits and very low supply voltage levels. In this paper the feasibility of using internal thermal sensors to detect heat sources provoked by structural defects are considered and evaluated.     

Thermal Testing of Analogue Integrated Circuits: A Case Study

This paper discusses the use of temperature as a test observable for analogue circuits, presenting a generic configuration for analogue circuit thermal testing. As a case study, static temperature analysis is performed over a two-stage operational amplifier in view of extracting temperature waveforms at different locations on the circuit under test, both under fault-free conditions as well as in the presence of bridging faults. Exhaustive thermal analysis of all the likely bridging faults is presented, establishing the detectability ratio of this fault set using temperature under different sensing scenarios.     

Magnetic Bead/Gold Nanoparticle Double‐Labeled Primers for Electrochemical Detection of Isothermal Amplified Leishmania DNA

A novel methodology for the isothermal amplification of Leishmania DNA using labeled primers combined with the advantages of magnetic purification/preconcentration and the use of gold nanoparticle (AuNP) tags for the sensitive electrochemical detection of such amplified DNA is developed. Primers labeled with AuNPs and magnetic beads (MBs) are used for the first time for the isothermal amplification reaction, being the amplified product ready for the electrochemical detection. The electrocatalytic activity of the AuNP tags toward the hydrogen evolution reaction allows the rapid quantification of the DNA on screen‐printed carbon electrodes. Amplified products from the blood of dogs with Leishmania (positive samples) are discriminated from those of healthy dogs (blank samples). Quantitative studies demonstrate that the optimized method allows us to detect less than one parasite per microliter of blood (8 × 10^?3 parasites in the isothermal amplification reaction). This pioneering approach is much more sensitive than traditional methods based on real‐time polymerase chain reaction (PCR), and is also more rapid, cheap, and user‐friendly.     

Hot-Spot Detection in Integrated Circuits by Substrate Heat-Flux Sensing

This letter presents a novel approach to detect hot spots (HSs) in active integrated circuits (ICs) and devices. It is based on sensing the HS heat flux within the chip substrate with a probe-laser beam. As the beam passes through the die, it experiences a deflection directly proportional to the heat flux found along its trajectory (internal infrared laser deflection technique). The proposed strategy allows inspecting the chip through its lateral sides (lateral access), avoiding the metal and passivation layers placed over the die. The obtained results demonstrate the suitability of this technique to locate and characterize devices behaving as hot spots in nowadays IC CMOS technologies.     

Calibration-free heat source localisation in ICs entirely covered by metal layers

The localisation of devices that generate periodically activated hot spots in a CMOS IC comprising five metal layers and metal fills is addressed. The feasibility of using the phase shift of the displacement of the uppermost metal layer due to thermal expansions is demonstrated.     

Electro-thermal characterization of a differential temperature sensor in a 65 nm CMOS IC: Applications to gain monitoring in RF amplifiers

This paper reports on the design solutions and the different measurements we have done in order to characterize the thermal coupling and the performance of differential temperature sensors embedded in an integrated circuit implemented in a 65 nm CMOS technology. The on-chip temperature increases have been generated using diode-connected MOS transistors behaving as heat sources. Temperature measurements performed with the embedded sensor are corroborated with an infra-red camera and a laser interferometer used as thermometer. A 2 GHz linear power amplifier (PA) is as well embedded in the same silicon die. In this paper we show that temperature measurements performed with the embedded temperature sensor can be used to monitor the PA DC behavior and RF activity.