Failure analysis of micro-heating elements suspended on thin membranes

We report on the degradation of platinum micro-heating elements operating at high temperatures. Devices with platinum heaters suspended on micro-machined dielectric membranes were self-heated at high temperature until failure. Optical and SEM observations combined with mechanical deformation measurements and Thermal Laser Stimulation techniques were used to analyze the failure mechanisms of the micro-heating elements. Platinum atoms migration and breaking of the membrane were two failure modes observed. At high temperature, the migration of the platinum atoms was linked to the mechanical stress in the dielectric membrane. The Thermal Laser Stimulation technique revealed the formation of vertical as well as lateral thermocouples at mechanically deformed areas. One explanation proposed is that those thermocouples are the result of Si diffusion from the Si3N4 membrane into the platinum heater as well as electro-stress migration of platinum atoms

Side-Channel Improvment by Laser Stimulation

International audienceThe purpose of failure analysis is to locate the source of a defect in order to characterize it, using dierent techniques (light emission, electromagnetic emission, laser stimulation, ...). A part of my research is to nd how it is possible to use the failure analysis tools and methods for security purposes. During cryptarchi 2009, I presented the possibility to use the leakage due to the light emitted during normal operation of a CMOS circuit, to set up a successfull attack on a part of a DES cipher algorithm implemented on an FPGA. In this talk a second method based on laser stimulation is presented. Indeed, Sergei Skorobogatov demonstrates the possibility to increase the power consumption of a SRAM cell in a microcontroller, by applying a photocurrent on its transistors. The experiment presented here, consist to extend the Skorobogatov method's to a DES cipher implemented on an FPGA in order to improve the "traditional" side-channel attack by injecting a photocurrent on a chosen specic area (contain SBOXs, XOR operation...). This additional current should increase the consumption of the circuit during the algorithm encryption, and thus improve the attack by reducing the number of power consumption acquisitions

Validation of Differential Light Emission Analysis on FPGA

International audienc

[Multiple cervical arterial dissections in two brothers: fibro-muscular dysplasia or connective tissue disease?]

International audienc

Computed tomography angiography in a patient with medial dibromuscular dysplasia

<p><b>Copyright information:</b></p><p>Taken from "Fibromuscular dysplasia"</p><p>http://www.OJRD.com/content/2/1/28</p><p>Orphanet Journal of Rare Diseases 2007;2():28-28.</p><p>Published online 7 Jun 2007</p><p>PMCID:PMC1899482.</p><p></p

Fibromuscular dysplasia

<p>Abstract</p> <p>Fibromuscular dysplasia (FMD), formerly called fibromuscular fibroplasia, is a group of nonatherosclerotic, noninflammatory arterial diseases that most commonly involve the renal and carotid arteries. The prevalence of symptomatic renal artery FMD is about 4/1000 and the prevalence of cervicocranial FMD is probably half that. Histological classification discriminates three main subtypes, intimal, medial and perimedial, which may be associated in a single patient. Angiographic classification includes the multifocal type, with multiple stenoses and the 'string-of-beads' appearance that is related to medial FMD, and tubular and focal types, which are not clearly related to specific histological lesions. Renovascular hypertension is the most common manifestation of renal artery FMD. Multifocal stenoses with the 'string-of-beads' appearance are observed at angiography in more than 80% of cases, mostly in women aged between 30 and 50 years; they generally involve the middle and distal two-thirds of the main renal artery and in some case also renal artery branches. Cervicocranial FMD can be complicated by dissection with headache, Horner's syndrome or stroke, or can be associated with intracerebral aneurysms with a risk of subarachnoid or intracerebral hemorrhage. The etiology of FMD is unknown, although various hormonal and mechanical factors have been suggested. Subclinical lesions are found at arterial sites distant from the stenotic arteries, and this suggests that FMD is a systemic arterial disease. It appears to be familial in 10% of cases. Noninvasive diagnostic tests include, in increasing order of accuracy, ultrasonography, magnetic resonance angiography and computed tomography angiography. The gold standard for diagnosing FMD is catheter angiography, but this invasive procedure is only used for patients in whom it is clinically pertinent to proceed with revascularization during the same procedure. Differential diagnosis include atherosclerotic stenoses and stenoses associated with vascular Ehlers-Danlos and Williams' syndromes, and type 1 neurofibromatosis. Management of cases with renovascular hypertension includes antihypertensive therapy, percutaneous angioplasty of severe stenoses, and reconstructive surgery in cases with complex FMD that extends to segmental arteries. The therapeutic options for securing ruptured intracerebral aneurysms are microvascular neurosurgical clipping and endovascular coiling. Stenosis progression in renal artery FMD is slow and rarely leads to ischemic renal failure.</p