Micro-inductors integrated on silicon for DC-DC converters

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.