For applications such as computers, cellular telephones and Microsystems, it is essential to reduce the size and the
weight of DC-DC converters. To miniaturize passive components, micromachining techniques provide solutions based
on low-temperature process compatible with active part of the converter. This paper deals with the integration on silicon
of "spiral-type" inductor topology. Electroplating techniques are used to achieve the copper conductor and the CoNiFe
laminated magnetic core and several investigations on the electroplating bath's parameters have been realized in order to
obtain the adequate magnetic properties. Finally, a 1μH micro-inductor prototype has been characterized.
In portable electronic equipments, miniaturisation, cost, multi-functionalities and reliability are the main factors driving the power electronics industry. In this context, the realisation of all integrated high performance DC-DC micro-converters working at high frequencies (few MHz) is necessary. The passive components such as inductors, transformers and capacitors, are for the moment the bulkiest components and their integration on silicon substrate would constitute a real improvement in term of compactness and reliability of power converters. This paper deals with the fabrication of integrated capacitors realised on silicon using MEMS-type techniques. High capacitance density, low series resistance and inductance are sought. Structures using deep cavities etched in silicon were realised in order to increase the effective area of the capacitor's electrodes while minimising the area on the substrate. The development of micro-fabrication techniques such as Deep Reactive Ion Etching (DRIE) and doped-polysilicon deep trenches filling are presented. Some preliminary measurement on the fabricated capacitors with the developed processes show that high capacitance density (36 nF/mm2) can be obtained.
The market of portable instruments is growing more and more. For applications such as computers, cellular phones and microsystems, it is essential to reduce size and weight of electronic devices, including power unit supplies associated with these products. This evolution will require high efficiency on-chip DC-DC converters providing low voltage for the various Ics. Therefore, fabrication of magnetic components dedicated to power conversion becomes necessary. To miniaturize inductors, the micromachining techniques provide solutions based on low-temperature process compatible with active part of the converter. In this paper, a "spiral type" inductor topology designed for power electronics application is investigated. Thick resist molds photolithography and electroplating techniques are used to achieve the copper conductor and the NiFe laminated magnetic core.
P+ walls through wafer can be considered as key regions in the 3D architecture of new bi-directional current and voltage power integrated devices. Moreover, these P+ walls can be used as electrical vias in the design of microsystems, in order to make easier 3D packaging. In this paper, we demonstrate the possibility of fabricating these P+ walls combining the deep RIE of silicon and deposit of boron-doped polysilicon.