*========================================================================* | I O N | *------------------------------------------------------------------------* | News and views within the Ion Beam Community | *========================================================================* | Authors bear full responsibility for their contributions | *========================================================================* I O N Friday, September 8 2000 Volume 2000 : Number 011 "Ian Vickridge" : Research associate position in France ---------------------------------------------------------------------- Date: Thu, 7 Sep 2000 12:03:52 +0200 From: "Ian Vickridge" Subject: "Ian Vickridge" : Research associate position in France The CERI, in Orleans, France, is seeking candidates for a research associate position to study Helium and cavities in He-implanted silicon. The ideal candidate would have at least one post doctoral experience. He or she will have a Ph.D in materials sciences or in electronics devices as well as extensive experience with at least one of the following topics: Ion implantation Electrical characterization of semiconductors Characterization by microscopy (TEM) NRA (nuclear reaction analysis) Power devices Modelling experience is an advantage The position is for one year, renewable. It can start as early as January 2001. Salary is Ffr12500/month net, plus insurances. For additionable information and candidatures, contact Esidor Ntsoenzok : esidor@cnrs-orleans.fr Programme details follow ..... *************************************************** Helium and cavities in He-implanted silicon Cavities induced by helium implantation in silicon are known to be very efficient sites for the gettering of impurities. Metallic impurities are particularly known to have a deliterous effect in both integrated and power devices. These impurities must be removed to avoid the failure of devices. In the case of integrated circuits, the projected specifications for future silicon devices give a maximum metal impurity content of 2.5´109 atoms/cm2 by the year 2007. Helium is still however one of the most important issue to be solved. Both its interaction with cavities and its desorption need to be carefully studied. The following work program will be adopted: 1- Implantation We will work with both the Van de Graaff (CERI-CNRS) and the implantor (LMP, Tours) to perform cavities at various depth. The two machines allow us to access a large domain of energies ranging from some keV to MeV. Additional implantation will be made by using MeV implantation and various energy attenuators atop the sample. These attenuators will include aluminium foils, SiO2 layers, ... These last implantations must provide the way to localize both helium and cavities at different depths by using the same incident energy and then keeping the total deposit energy roughly constant at a given dose. As implanted and annealed samples will then be characterized by the means of various methods. Many temperature and annealing times will be applied to implanted samples. 2- Determination of the remaining concentration of helium The concentration of helium remaining in silicon will be determined by using Nuclear Reaction Analysis (NRA). The method allows the study of helium with a very good detection limit. At the present time, this detection limit is about 1013 He/cm3. This one of the better detection limit which can be reached by such a method. It is therefore a well suited method for the study of helium desorption from silicon. In addition, the set up will be improved in order to allow in-situ measurements. 3- Growth of cavities The growth of cavities will be studied by using the transmission electron microscopy (TEM). The studies by TEM provide many data such as the size of cavities, their density and other defects (dislocations) inside or outside the cavity layer. Both plane and cross-sectional micrographies can be done. All these micrographies will be combined with the measured helium concentration in order to determine the impact of helium in the growth of cavities. The combination of paragraphs 2 and 3 must lead to the implementation of new helium release models and to a best understanding of the growth mechanism of cavities. 4- These studies will be completed by a modelisation of behavior when escaping from bulk to surface. Different samples having different point defect concentration in the region between the surface and the cavity layer will be analyzed by the positron annihilation method. The positron technique allows the determination of vacancy type defects (from monovacancy to vacancy clusters and vacancy-impurity complexes). Different techniques like positron lifetime and slow positron beam are available. The desorption speed of helium in these different samples will be measured. This could allow us to determine if the move of helium from the bulk is via vacancies or only interstitially. 5- Finally, we will test the gettering efficiency for samples containing cavities with various helium concentration. Many metallic impurities will be tested they will include fast diffuser like copper, iron, gold, ... This will be done by both secondary ion mass spectroscopy (SIMS) and by the spreading resistance (SRP). Additional characterization set up will include: - - DLTS (deep levels transient spectroscopy) - I-V (current - voltage) - Numerous furnaces The program can be achieved in two years ------------------------------ End of I O N V2000 #11 ********************** *-----------------------------------------------------------------------* | I O N - part of the IBIS, the Ion Beam Information System | *-----------------------------------------------------------------------* | Editors: | | E. Szilagyi (szilagyi@rmki.kfki.hu) | | G. 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