Aurélie Girard

Transferrin Electronic Detector for Iron Disease Diagnostics

Field effect transistor (FET) structure with suspended bridge shows the ability to detect proteins with very high sensitivity. This sensor is tested for the transferrin, a specific blood plasma protein, relevant in iron disease diagnostic. This system is based on field effect transistor with a suspended bridge used as a gate electrode. The sensitive layer is made of silicon nitride as in the ISFET (ion sensitive field effect transistor) technology. The surface micro-technology ensures a small height suspended-bridge (0.5 mum) composed of poly-silicon insulated with silicon nitride. To improve sensitivity and to limit biofouling, proteins are selected by antibodies covalently bound to organic layers. The specific charge of the fixed transferrins translates the transistor transfer characteristics. For low concentration, resulting shift is important and confers a good sensitivity to our electronic transducer.

Low Concentrated DNA Detection by SGFET

In this work a device based on oligonucleotide hybridization charged detection is presented. This biosensor is a SGFET (suspend gate field effect transistor), it is based on a MOSFET (metal oxide semiconductor field effect transistor) structure whose gate is suspended. The insulating layer (empty gap) is chemically modified by immobilized molecular receptors that enable miniaturized label free DNA detection. This method allows direct, time-resolved and in situ detection of specific nucleic acid binding. By the use of SGFET, the immobilization of DNA sequences brings negatives charges due to their phosphate groups under the gate and induce large shift of transfer characteristic. One of the applications of this device can be clinical testing.

Direct Electrical Detection of Biological Species

Suspended-Gate FETs, namely SGFET, with sub-micron gap, is shown to be able to detect biological species with very high sensitivity in a large range of concentration. Examples of detection of DNA (through the DelF508 mutation of the cystic fibrosis gene that is widely disseminating in Europe and North America, and one mutation of BRCA1 gene that is the main indication of the possibility for a woman to have breast cancer) and proteins (through the transferrin that is the only carrier of iron in blood) are presented. This very sensitive electrical detection without any labelling is shown to deliver directly readable signal.

Modeling of silicon etching using Bosch process: Effects of oxygen addition on the plasma and surface properties

The authors developed a tool using a multiscale approach to simulate the silicon etching using Bosch process. Their study is focused on the analysis of the effect of the oxygen addition to C4F8 plasma during the deposition pulse. This is the complementary study that the authors have recently published which was dedicated to the Bosch process under pure SF6 plasma used in etching pulse and pure C4F8 plasma used in polymer deposition pulse. Parametric study about the effect of the oxygen percentage on the reactive species flux evolution and their impact on the deposition kinetic during the deposition pulse has been performed. The simulation results reveal that for a low %O2 in a C4F8/O2 plasma mixture, the atomic fluorine density increases because of the volume reactions, especially recombinations between CFx and O which favor the production of fluorine. This leads to the decrease of CFx to F flux ratio. Ion energy distribution functions (IEDF) plotting reveals the impact of both %O2 and mass of the positive ions on the IEDF shape. Finally, both the experimental and simulation results show that in their pressure range, the addition of O2 to C4F8 plasma has a weak impact on the silicon etch profile and the etching rate, except for a high %O2 which the etch anisotropy begins to be degraded.The authors developed a tool using a multiscale approach to simulate the silicon etching using Bosch process. Their study is focused on the analysis of the effect of the oxygen addition to C4F8 plasma during the deposition pulse. This is the complementary study that the authors have recently published which was dedicated to the Bosch process under pure SF6 plasma used in etching pulse and pure C4F8 plasma used in polymer deposition pulse. Parametric study about the effect of the oxygen percentage on the reactive species flux evolution and their impact on the deposition kinetic during the deposition pulse has been performed. The simulation results reveal that for a low %O2 in a C4F8/O2 plasma mixture, the atomic fluorine density increases because of the volume reactions, especially recombinations between CFx and O which favor the production of fluorine. This leads to the decrease of CFx to F flux ratio. Ion energy distribution functions (IEDF) plotting reveals the impact of both %O2 and mass of the positiv...