A method comprises forming an etch stop layer, a first titanium layer, a magnetic core, a second titanium layer, and patterning the first and second titanium layers. The etch stop layer is formed above a substrate. The first titanium layer is formed on the etch stop layer. The magnetic core is formed on the first titanium layer. The second titanium layer has a first portion encapsulating the magnetic core with the first titanium layer, and a second portion interfacing with the first titanium layer beyond the magnetic core. The patterning of the first and second titanium layers includes forming a mask over a magnetic core region and etching the first and second titanium layers exposed by the mask using a titanium etchant and a titanium oxide etchant.