Electroplated thick permanent magnet arrays with controlled direction of magnetization for MEMS application

We have successfully developed a technique to electroplate thick CoNiMnP-based permanent magnet arrays with controlled direction of magnetization and improved magnetic properties by applying external magnetic fields during electroplating. The magnet arrays with individual magnet shapes and sizes were fabricated on a Si substrate using micromachining and electroplating techniques. The magnetic properties of these magnets have been characterized with the vibrating sample magnetometer. The optimized processing conditions with external magnetic fields during electroplating have improved the coercivity and the retentivity of the magnets by more than 200% and 350%, respectively, comparing with those without external magnetic fields. This paper describes the process for fabricating the magnets and the effect of external magnetic fields in controlling and improving the properties of the magnets. In addition to the capability of full scale integration, the high vertical anisotropy of thick magnet arrays can be used for many MEMS device applications. (C) 2000 American Institute of Physics. [S0021-8979(00)75108-5].