New deposition process and design for CoPtP micromagnets

Rare-earth material free permanent magnets, such as hard-ferromagnetic alloys and compounds, are incredibly useful in semiconductors and microelectromechanical systems (MEMS) — cornerstones of today’s miniaturized tech world. Developing more efficient and cost-effective micromagnets is a difficult challenge, particularly in creating those for complementary metal-oxide-semiconductor (CMOS) technology.

Cobalt-rich CoPt alloys are a promising group of materials for these applications due to their magnetic properties. In a new paper by Mallick et al., they report a new fabrication process and material characterizations for the Co-rich CoPtP films as a potential candidate for MEMS.

The researchers tested films with different thicknesses ranging up to 26 micrometers, and reported the relationship between the thickness and magnetic properties. They discovered that a film with a thickness around 3 micrometers possesses the highest in-plane and out-of-plane coercivity. For films thicker than 9 micrometers, the coercivity decreases as the thickness increases.

The researchers also reported a method for creating their smooth, crack-free films. They used an electrochemical bath with saccharin to reduce stress in the material, combined with a pulse-reverse technique that uses forward and reverse pulses with duty cycles. They also proposed a new design strategy for implementing Co-rich CoPtP in MEMS devices by optimizing the micropatterning structures, which resulted in minimized demagnetization of the fields of the magnetic elements. Using micropatterning thus can provide significant advantages over standard film magnets in a range of magnetic MEMS and microfluidic devices. Future work can test this strategy on fabricated micromagnets.

Source: “Magnetic performances and switching behavior of Co-rich CoPtP micro-magnets for applications in magnetic MEMS,” by Dhiman Mallick, Kankana Paul, Tuhin Maity, and Saibal Roy, Journal of Applied Physics (2018). The article can be accessed at https://doi.org/10.1063/1.5063860 .