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Dielectric Insulation for Magnetoresistive Sensors in Thin Film Recording Heads Disclosure Number: IPCOM000016667D
Publication Date: 2003-Jul-08
Document File: 3 page(s) / 49K

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The Prior Art Database


Disclosed is an improved dielectric layer for thin film magnetic recording heads, which incorporates amorphous diamond films with superior resistance to ion beam etching, also known as ion milling. This allows the use of thin dielectric gap layers necessary for high density data storage applications without negatively affecting manufacturing yields.

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Dielectric Insulation for Magnetoresistive Sensors in Thin Film Recording Heads

  Giant magnetoresistive (GMR) sensors are used in magnetic recording heads to detect magnetic bits written on disks or other magnetic media. The width of GMR sensors is one of the primary metrics determining the minimum permissible distance between adjacent data bits and hence storage density. The physical width of a GMR sensor is most often defined by ion milling process where energetic ions bombard and physically remove sensor materials outside the actual sensing region. Masking layers, polymeric photoresist in many cases, protect the sensing region during ion milling. These masking layers have finite thicknesses and shadow ion beams incident on areas near the sensor edge. The shadowing can result in extended tails, where magnetically active materials extend far beyond the intended sensing region. To define sharper edge and hence improve the spatial resolution of the sensor, the time of ion milling is often set to be greater than what would be required to mill through a full sensor film of the same thickness without the shadowing effect. This practice is often called overmill. This is problematic for high recording density applications because ion beams damage dielectric layers separating GMR sensors from surrounding magnetic shields causing electrical shorts. The thickness of these dielectric layers, often referred to as gap dielectric, is approximately 150A for the latest generation of GMR heads and is getting smaller with each product generation.

Top Shield

Bottom Shield

Top Dielectric Gap

Figure 1. Schematic of a GMR read head

The present invention addresses this problem by incorporating a thin film with very high ion milling resistance as part of the gap dielectric layer underneath a GMR sensor. Our preferred embodiment uses amorphous diamond films synthesized using the filtered cathodic arc, direct ion beam, or pulsed laser deposition technique. Such amorphous diamond films have ion milling resistance more than two times greater than that of aluminum oxide films widely used as gap dielectric.

The ion mill resistive layer can be sandwiched between the GMR sensor and the main


Lead Lead

GMR Sensor

Bottom Dielect...