Research On Low Temperature Deposition Of NiZn Ferrite Thin Film By Spin-spray Technology

With the rapid development of the electronic information industry,there is an increasing demand for planar integration,small size,light weight,and high frequency of electronic components.Traditional ferrite film preparation technology requires high temperature conditions,which prevents its application in electronic components.In this paper,in response to the system-on-chip(So C)demand for low-temperature deposition of thin-film magnetic cores,the spin-spray method is used to study low-temperature deposition of Ni Zn ferrite films.This paper focuses on the influence of the precursor solution,oxidizing solution and preparation process of the spin-spray method on the0.2mm glass substrate with phase structure,microscopic morphology and magnetic properties of Ni Zn ferrite films.The research results of precursor solution(including Fe Cl₂,Zn Cl₂,Ni Cl₂)show that:(1)With the decrease of Fe content in the main formula,the average crystal grains decrease,the uniformity of crystal grains increases,the preferred orientation of(222)direction is enhanced,the crystal grains have a triangular morphology.The film saturation magnetization M_s decreases,and the coercive force H_c decreases.Small,the real permeability?'increases,and the cut-off frequency f_r decreases.(2)With the increase of Zn content in the main formula,M_s first increases and then decreases,the H_cdecreases,the?'increases,and the f_r decreases.When the main formula is Ni_0.09Zn_0.68Fe_2.23O₄,the real permeability with 100MHz can reach the maximum value of 95.5.(3)Adding Co²⁺ions to the main formula Ni_0.17Zn_0.52Fe_2.31O₄,the uniformity of the crystal grains is reduced,the H_c is increased,the M_s is reduced,and the?'_100MHzdecreases,the f_r increases.When the main formula is Ni_0.17Zn_0.52Co_0.09Fe_2.22O₄,the cut-off frequency can reach the maximum value 1.0GHz.(4)Add acetic acid to the precursor solution(P solution)to adjust its p H value.As the acetic acid increases,the p H(P)value decreases,the coercive force increases,the saturation magnetization and the real permeability(100MHz)first increases and then decreases,but it is not obvious.The maximum saturation magnetization is 437k A·m^-1.The research results of the oxidation solution(containing Na NO₂ and CH₃COONa)show that:(1)Add a small amount of acetic acid to the oxidation solution(O solution)to form an acetic acid-sodium acetate buffer pair in O solution.As the acetic acid increases,the p H(O)value decreases,the coercivity increases,the saturation magnetization and the real permeability(100MHz)?'100MHz first increase and then decrease,the maximum saturation magnetization is 491k A·m^-1,and the saturation magnetization increases by nearly 25%.(2)Adding ammonia to the oxidizing solution(O solution),the p H value of p H(O)increases,the H_c first increases and then decreases,the M_s and the?'_100MHz increases first and then decreases,the maximum M_s is486k A·m^-1,and the deposition rate first decreases and then increases.When the p H(O)is 10.2,the deposition rate is as high as 70nm·min^-1.(3)As the oxidant Na NO₂ in the oxidation solution increases,the crystallinity and deposition rate increase,the average grain size increases,the H_c decreases,the M_s and the?'_100MHz increase.(4)When there is no buffer in the oxidizing solution,?-Fe₂O₃ is formed,and Ni Zn ferrite cannot be formed.As the buffer CH₃COONa increases,the deposition rate and average grain size increase,the H_c first decreases and then increases,the M_s and the?'_100MHz first increase and then decrease.However,excessive buffering agent can lead to agglomeration of crystal grains.(5)When the buffer is the same amount of CH₃COONH₄,the deposition rate decreases,the coercive force increases,the saturation magnetization,the real permeability(100MHz)and the cut-off frequency all decrease.The process research results show:(1)Add 1?5%ethanol to the precursor solution and oxidizing solution,the contact angle is reduced from 58°to 35°,the solution wettability and the crystallinity increase,the saturation magnetization and the real permeability(100MHz)first increases and then decreases,and the saturation magnetization M_s reaches 458 k A·m^-1.The first-order inversion curve FORC graph shows that the coercive force distribution becomes narrower after the addition of ethanol,the grain growth is more uniform.And the columnar structure results in the in-plane coercive force Increase,the out-of-plane coercivity decreases.In the 3%ethanol sample,the H_c-?of the parallel magnetic field reaches the maximum value(1.23 k A·m^-1),the H_c-?of the vertical magnetic field reaches the minimum value(1.35k A·m^-1).(2)A 3%ethanol aqueous solution was used to coat four substrates with different materials on the surface of glass,Si-Si O₂,Si-Si O₂-PI,Si-Si O₂-PI-Si₃N₄,to achieve dense and uniform growth on Si₃N₄ coated silicon substrates(100)Ni Zn ferrite film with triangular grains.(3)When the substrate surface temperature is about90?95?,it is easier to form a high-quality film.When the substrate temperature is too low,a Ni Zn ferrite film cannot be formed.When the temperature is too high,the crystal grains will agglomerate.(4)As the deposition time increases,the average grain size gradually increases,the deposition rate first decreases and then stabilizes,and gradually increases with the film thickness.The saturation magnetization M_s of the Ni Zn ferrite film increased,the coercivity H_c decreased,the real permeability of 100MHz??_100MHzincreased,and the cut-off frequency f_rdecreased from 0.32GHz to 0.23GHz.(5)Rotation speed has little effect on the micromorphology of crystal grains,deposition rate,saturation magnetization and the real permeability(100MHz).(6)When the nozzle flow rate is 13?17m L·min^-1,the Ni Zn ferrite film has the better quality,and the saturation magnetization reaches 394 k A·m^-1.If the flow rate is too low,the crystal grains will agglomerate.