The Adjusting On Performance Of Soft Magnetic Films And Integration Technology Of Devices In Ghz Frequency Band

The integration of high frequency magnetic devices has become the obstacles of the development of electronic information industry and internet of things(IoT). The soft magnetic thin film with high performance is one of the main challenges. The basic requirements for soft magnetic films include high saturation magnetization, high electric resistivity, high stability, low coercivity and suitable resonant frequency. In addition,with the films trend toward to miniaturization and graphical, the changing on electromagnetic performances of films must be considered. Based on the above requirements, soft magnetic FeCo TiO nanogranular thin films are fabricated using radio frequency(rf) magnetron sputtering, the electrical and magnetic properties of films are studied. Separately on the basis of the specific application requirements of the devices,the properties of magnetic thin films are improved further. Finally, combining with microelectronics technology, the anti-electromagnetic interference noise suppressor and on-chip integrated inductor have been developed.A series of magnetic nanogranular FeCo TiO films with different thickness and sputtering power are deposited by RF magnetron sputtering. The control of films performance is preliminarily realized, the adjustable range of resonance frequency(fr)reaches 1 GHz. By changing the content of FeCo magnetic phase the control of the saturation magnetization and resistivity in a wide range has been realized. With the increase of FeCo content x from 0.58 to 0.9, the resistivity decreases from 1732 μΩcm to 365 μΩcm, the saturation magnetization increases from 11.3 kGs to 19 kGs, and fr first increases and then decreases, reaching the maximum fr =3.2 GHz when x=0.68. In order to achieve a broader range of resonance frequency regulation, the oblique sputtering has been used. With the oblique angle increae from 10° to 45°, the anisotropy field increases from 51 Oe to 270 Oe, and fr changes from 2.5 GHz to 6 GHz. In addition, the films keep good temperature stability from room temperature to 80 ℃.A series of soft magnetic nanogranular FeCo-Ti-O films with different Ti contents were fabricated on Si substrates by co-sputtering. By adjusting the Ti content, it appears that the imaginary part of the permeability spectra of FeCo-Ti-O films changes from a single peak to double peaks then to a single peak. Frequency conversion ferromagnetic resonance(FMR) analysis evidences that double FMR peaks can be found in all threefilms, which were attributed to two magnetic phases, i.e. nanocrystalline FeCo Ti phase and amorphous FeCo TiO phase embedded in amorphous TiOx matrix. Structural and temperature dependent resistivity analysis support such three component microstructure.Based on this phenomenon, multilayered(FeCoTiO/SiO2(50 nm))n films with various thickness of FeCo TiO layer were deposited and the characteristics of the electromagnetic noise suppression have been evaluated. The absorption attenuation amplitude reaches to-8 dB at the resonance frequency, and is better than-6 dB for the frequency above 3 GHzThe research and development of on-chip integrated inductor is the core content of the integration of high frequency magnetic devices. At first, the design parameters of solenoid inductors are optimized using the commercial HFSS software to achieve a high inductance and quality factor. Then, a series of FeCo TiO thin films are deposited using oblique sputtering and stripe patterning at the same time to study the influence of boundary effect and demagnetizing field on small size and graphical films. By using the FM/NM/FM sandwich structures, the influence of shape anisotropy will be suppressed by the exchange coupling effect. At last, On-chip integrated solenoid inductors have been fabricated using nanogranular FeCo TiO magnetic core. An inductance of 14.2 nH is achieved while keeping the device area of 0.14 mm2 and the resistance of 0.65 Ω. The quality factor is 7.5, and the saturation current reaches to 450 mA.The solenoid inductors with different thickness of magnetic core have been comparative studied. It was found that multilayered magnetic core structure is very helpful to improve permeability and suppress the hysteresis loss due to edge magnetic domains. The enhancement of both inductance area density and quality factor was achieved by adjusting the geometry of magnetic core to reduce the demagnetization factor. Our results clearly indicate that even a slight reduction of demagnetization factor is not trivial for magnetic core with high permeability. At last, two kinds of coupling inductance have been designed and prepared, the results show that closed magnetic circuit coupling inductance have a greater inductance and Q factor, but the open-circuit coupling inductance the advantage of coupling factor.