Fabrication Of Planar Spiral Inductor With Magnetic Core By MEMS

Power management chip like DC/DC converter is developing towards to microminiaturization along with the miniaturization of portable electronic product. Integrated inductor with high performances is essential for the characteristics of the power management system such as decreasing ripple current, increasing load current and power transfer efficiency. So there has been a great demand for microinductor with high performances in the market. There are several key requirements for the microinductor that must be satisfied in the DC/DC converter such as: adequate inductance and quality factor to store energy, small size, current handling and ease of fabrication. With the development of MEMS techniques, realization of the high performances microinductor becomes feasible. Microinductor fabricated by MEMS technique combined with thin film technique will possessed the merits of low resistance, high inductance and Q-factor, low product cost and batch fabrication. It will be applied in every kind of micro power management system.The content in this thesis includes four parts. First, test the magnetic core material with the VSM and Agilent E4991A RF impedance/material analyzer. Second, use the calculation method of planar spiral coil, magnetic head model andπ-shaped lumped element model through the Maxwell equations to characterize and design the microinductor. Third, use MEMS techniques such as lithography, electroplating, magnetron sputtering, dry/wet etching and polyimide technique to fabricate the microinductor with different parameters. And last, use the HP4194A and Agilent E4991A RF impedance/material analyzer to test the performances of microinductors. The results show that FeCuNbSiB nano-crystalline ribbon annealed at 500℃is suitable for the magnetic core. Microinductors with the number of turns between 15 and 20 have both relatively high inductance and Q-factor in the range of 1-10MHz.