Fabrication Of Planar Sprial Inductor With Magenatic Core By MEMS Technique

Power management chip like DC/DC converter is developing towards tomicrominiaturization along with the miniaturization of portable electronic product.Integrated inductor with high performances is essential for the characteristics of the powermanagement system such as decreasing ripple current, increasing load current and powertransfer efficiency. So there has been a great demand for microinductor with highperformances in the market. There are several key requirements for the microinductor thatmust be satisfied in the DC/DC converter such as: adequate inductance and quality factorto store energy, small size, current handling and ease of fabrication. With the developmentof MEMS techniques, realization of the high performances microinductor becomes feasible.Microinductor fabricated by MEMS technique combined with thin film technique willpossessed the merits of low resistance, high inductance and Q-factor, low product cost andbatch fabrication. It will be applied in every kind of micro power management system.The content in this thesis includes Three parts. First, use the calculation method ofplanar spiral coil, magnetic head model and π-shaped lumped element model through theMaxwell equations to command the theory. Second, use MEMS techniques such aslithography, electroplating, magnetron sputtering, dry/wet etching and polyimide techniqueto fabricate the microinductor with different parameters. And last, use the HP4194A RFimpedance/material analyzer to test the performances of microinductors. The results showthat FeNi magnetic core Microinductors with the number of22turns30widths and30spaces have a good performance of indunctance and Q-factor.Under1MHz, the inctanceis about1.1μH,the Q-factor is about1.Under20MHz, the inctance is about0.6μH,theQ-factor is about2.2.The results also shows that between15and20have both relativelyhigh inductance and Q-factor in the range of1-20MHz.