Ultra-high sensitive magneto-resistance film material and preparation method thereof

Abstract

The invention discloses an ultra-high sensitive magneto-resistance film material and a preparation method thereof, and relates to magnetic film material. The film material has the structure of a buffer layer / MgO / NiFe / MgO / protection layer; and then, high temperature annealing is carried out in magnetic field. The material with the structure has high magnetic field sensitivity, and a magnetic sensing element processed by the material also has high magnetic field sensitivity. The method mainly has the advantages that the material has simple structure and design, and obviously improves the magnetic field sensitivity which is basically equivalent to the magnetic field sensitivity of tunnel magneto-resistance (TMR) film materials and corresponding elements; meanwhile, in the original material system technique, when the NiFe layer is thinner, the phenomenon of 'magnetic dead layer' caused by solid phase reaction at the film interface of material or a device which is processed at certain temperature can be overcome; therefore, the material can be used for making a high sensitive magneto-resistance sensing component.

Description

technical field [0001] The invention relates to a magnetic thin film material, in particular to a highly sensitive magnetoresistance thin film material and a preparation method thereof. Background technique [0002] Anisotropic magnetoresistance (AMR) permalloy thin film material (NiFe) can be used to make application devices such as computer hard disk read head, magnetic random access memory and various magnetic sensors, and is widely used in automation technology, household appliances, navigation systems, mobile In the fields of communications, large-capacity storage and computers, especially in geomagnetic measurements, AMR thin film materials have better direction sensitivity than giant magnetoresistance (GMR) and tunnel magnetoresistance (TMR) thin film materials, and anisotropic magnetic Resistivity has a quantitative relationship with angle: ρ(θ)=ρ ⊥ +Δρcos 2 θ, so this material has broad application prospects in geomagnetic navigation and other fields. In addition...

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Problems solved by technology

At the same time, the shunting effect of the seed layer and the protective layer is also more obvious. At this time, it is difficult for the thin film material to maintain a good magnetoresistance change rate (ΔR / R) and magnetic field sensitivity (S v )

In order to ensure that the ultra-thin NiFe film has a larger magnetoresistance change rate and higher magnetic field sensitivity to meet the needs of magnetic sensors, etc., in the literature W.Y.Lee, M.Toney, P.Tameerug, E.Allen and D. Mauri, J.Appl.Phys.87, 6992 (2000) proposed to use (Ni 0.81 Fe 0.19 ) 1-x Cr x or Ni 1-x Cr x Ni prepared as a seed layer 0.81 Fe 0.19 film, its AMR value is higher than that of Ni with Ta as the seed layer 0.81 Fe 0.19 The AMR value of the film has been significantly improved. For example, the AMR value of the 12nm thick NiFe film has reached 3.2%.

In the literature H.Funaki, S.Okamoto, O.Kitakami, and Y.Shimada, Jpn.J.Appl.Phys., Part 233, L1304 (1994), it is proposed that the use of annealing can significantly improve the ΔR / R value, such as 20nm thick Permalloy thin film, after annealing at 400°C, the ΔR / R value can reach 3.5%, but this is obtained without a buffer layer and a protective layer. When making an AMR device, use buffer layer and protective layer, and the thickness of the film is only a few to a dozen nanometers, it is difficult to maintain ΔR / R and S after annealing v good indicator of

In the literature Lei Ding, Jiao Teng, Qian Zhan, Chun Feng, Ming-hua Li, Gang Han, Li-jin Wang, Guang-hua Yu, and Shu-yun Wang, Appl.Phys.Lett.94, 162506 (2009) A new structure Ta / Al was designed 2 o 3 / NiFe / Al 2 o 3 / Ta film, after annealing at 380℃, Ta 5nm / Al 2 o 3 1.5nm / NiFe 10nm / Al 2 o 3 Compared with Ta 5nm / NiFe10nm / Ta 5nm, the magnetoresistance change rate of 1.5nm / Ta 5nm has increased by 250%, and the magnetic field sensitivity has been increased by 150%, reaching a magnetic field sensitivity of 1.3% / Oe, but its magnetic field sensitivity is not the same as that of tunnel magnetoresistance (TMR) thin film There is still a large gap between materials, one of the main reasons is that Al 2 o 3 It is very difficult to crystallize, and other easy-to-crystallize oxides must be found to maximize the scattering of spin electrons to improve ΔR / R and S v

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