Apparatus and method for intra process on wafer monitoring of deposited layer permeability

摘要

A monitoring apparatus is provided for determining permeabilities of a vacuum-deposited second pole piece of a magnetic head at the wafer level by providing wafer-mounted monitors which have layers formed by the same masking and deposition steps employed in making the magnetic heads so that the layers of the monitors are replicated layers, except for a shaping layer on top of a replicated second pole piece of some of the monitors. Each monitor is a transformer wherein each of a primary winding and a secondary winding comprises essentially a replicated magnetic head. The first and second pole pieces of the replicated magnetic heads are joined so as to magnetically couple the primary and secondary windings that constitute the transformer. The replicated shaping layer is omitted in part to expose a portion of one of the replicated second pole pieces of a monitor, such as the front slope, the back slope or the yoke portion of the replicated second pole piece which corresponds to the front slope, the back slope or yoke respectively of the magnetic head. When a current is conducted through the replicated coils of the monitor a voltage reading can be taken to indicate the permeability of the exposed portion of the replicated second pole piece of the monitor.