Electroless thin film CoNiFe–B alloys for integrated magnetics on Si

Tuning the Crystal Structure and Magnetic Properties of CoNiFeB Thin Films

“…Although earlier attempts , to synthesize CoNiFeB coatings via the electroless deposition method have reported interesting results, to our knowledge, there is no report on tuning the film composition and structure using electroless deposition from the same bath composition, and it is mentioned as a drawback of the electroless process . As suggested by previous studies, the crystal structure has a great impact on grain size and magnetic properties of CoNiFe films. , A body-centered cubic (BCC) structure offers a high B s , while a mixture of BCC and face-centered cubic (FCC) structures can improve the coercivity of the films showing a good combination of soft magnetic properties. ,, In this study, we will discuss the role played by various deposition parameters on the film composition, crystal structure, morphology and the magnetic properties, and show for the first time how the crystal structure of the CoNiFeB thin films can be controlled in order to go from a single-BCC phase to a single-FCC phase or have a mixture of BCC/FCC phases and tune the ratio only via optimization of the deposition parameters while maintaining the same concentration of salts in the bath.…”

“…Soft magnetic thin films with low coercivity ( H c ), high saturation magnetic flux density ( B s ), and high electrical resistivity (ρ) are used as the core material of high-density recording heads. , Many soft magnetic films of such transition metals as Fe, Co, and Ni and their alloys have been proposed as suitable candidates for integration into magnetic data storage technology. − NiFe alloys with low H c and relatively high B s were used for the first time as the core material in inductive heads by IBM . However, the interest in cobalt-containing alloys, such as CoNiFe, has recently grown, because of their promising characteristics, such as higher saturation flux density values. ,,, …”

“…7 However, the interest in cobalt-containing alloys, such as CoNiFe, has recently grown, because of their promising characteristics, such as higher saturation flux density values. 3,4,8,9 The most common technique for the fabrication of magnetic devices such as write-head cores with high aspect ratio is electrodeposition. 3 However, this method is limited to conductive surfaces and usually leads to film structures of uniform thickness and composition in the submicrometer scale.…”

“…At the other end of the spectrum, electroless deposition methods are much more attractive for use in the fabrication of metallic thin film structures, since they do not present any limitations associated with current density distribution and usually lead to uniform coatings on substrates with fine and complex geometries. 9,10 Although earlier attempts 8,9 to synthesize CoNiFeB coatings via the electroless deposition method have reported interesting results, to our knowledge, there is no report on tuning the film composition and structure using electroless deposition from the same bath composition, and it is mentioned as a drawback of the electroless process. 11 As suggested by previous studies, the crystal structure has a great impact on grain size and magnetic properties of CoNiFe films.…”

“…6,12 A body-centered cubic (BCC) structure offers a high B s , 13 while a mixture of BCC and facecentered cubic (FCC) structures can improve the coercivity of the films showing a good combination of soft magnetic properties. 3,8,12 In this study, we will discuss the role played by various deposition parameters on the film composition, crystal structure, morphology and the magnetic properties, and show for the first time how the crystal structure of the CoNiFeB thin films can be controlled in order to go from a single-BCC phase to a single-FCC phase or have a mixture of BCC/FCC phases and tune the ratio only via optimization of the deposition parameters while maintaining the same concentration of salts in the bath.…”