High Altitude Memory Test – HAMLET

Due to technological integration, electronic devices are sensitive to natural radiations in atmosphere. This radiative constraint is a real concern for components manufacturers. IBM has devoted a special issue (may 2008) of its Journal of Research to this topic. It is explained that atmospheric radiations are a real concern and must be addressed to carry the technological integration on. These radiations are essentially neutrons from ground level up to higher than avionic altitudes (20km). In order to address this constraint, it is necessary to evaluate the radiation abundance as well as determining some ways of testing which must be adapted to the technological evolution. At this time, the community does have neither data nor satisfactory test methods: * The radiative environment is not well known and no data exist at high altitude (avionic altitudes >12km), where the electronic reliability is however critical. * Test under beams does not allow a comparison with the real natural environment. Real time tests are then an alternative. Tests at the top of a mountain are nevertheless very long (one year or more). Since a new technology is developed each 18 months, this test is not satisfactory for a systematic study. HAMLET aims to address these problematic with an original point of view and by proposing new methods which are in breach with usual ones. There are five main objectives of the Hamlet project that are i/ to propose and develop a new way of testing since the conventional ones are not satisfactory, ii/ to provide information on the neutron environment at high altitude since no data exist, iii/ to link experiments in natural environment with conventional experiments, iv/ to perform experiments able to validate simulation tools and v/ to predict the reliability of future technologies. Information obtained during experiment will allow validating assumptions made on the phenomena which lead to errors in memories. These phenomena include nuclear physics, semiconductor physics and the consequences on the circuit. Finally, this will lead to evaluate the reliability of component and system in terrestrial environment. The innovating feature of the Hamlet project is to perform experimental tests at high altitude by using stratospheric balloons. This has never been done. This is only possible with the help of the CNES, which is the worldwide leader in balloon flight. Such experiment allows obtaining many events in the on-board devices, which will be developed for this project. These devices will provide information on the neutron environment and on the reliability of lifted components. There are two kinds of devices which will be developed and lifted with the balloon: 1- A neutron detector to characterize the radiative environment 2- An SRAM test bench In addition, experiments with the same devices will be performed in a known radiative environment that is to say under neutron beams. For the first time it will be possible to compare directly the behaviour of a device in a real environment with its behaviour under beam. Moreover, the ASTEP project will use the same SRAM device at the Pic de Bure and one more comparison could be achieved. Every experimental data will be compared with simulations codes already developed. Thus, an overall vision of the radiation effect issue will be possible with the link between the state of the art of experiment and modelling. Performing tests at high altitude today is crucial since it shows the future issues at ground level for integrated technologies. Yet, with the technology shrinking the radiation effect observed at high altitude will be soon a great concern even at ground level. Therefore, not only the aerospace community will be concerned but also terrestrial applications, especially automotive. This motivating project is only possible because of the quality of the consortium. Each team has one or more qualities that are required for the project. Scientifically, there is no expected point which could compromise the project: each partner of the consortium has expertness on its task: University of Montpellier II (IES-RADIAC), TRAD, IM2NP, ATMEL and CNES. The flights could be the first ones of numerous flights which aim to characterize the reliability of components. Such flights could lead to define a methodology of evaluation for microelectronic devices and the setting up of devices evaluation tool. Europe would then have a unique expertness, leading to beneficial repercussions on aeronautics and automotive fields which are concerned with radiation. Let us notice that AIRBUS is already aware of this problem in the framework of the 'electrical plane' and VALEO, BOSCH, SAGEM ' are concerned with the driver assistance. Hamlet aims to propose solutions to the European industry.