Macroscopic probing of the joint between metals in MR heads

During the wafer manufacturing process of magnetoresistive (MR) heads which are widely used in Hard Disk Drives, the metal leads are deposited on both sides of the MR sensing element through the photoresist masks. Due to the shadowing effect of the photoresist, there may be some contamination at joint interfacial region even after ion etching. This introduces additional contact resistance and causes some region of the sensing element to be unpinned. As the geometry of the sensor element decreases, and the contamination, located in regions of few thousands of angstroms, is becoming more severe for MR head than ever. In this paper, we developed a systematic method to evaluate the contact resistance between the two metal layers. A comparison was made between the magnetic read width and the physical width. Finally TEM analysis successfully revealed the interfacial junction contamination.