Method of configuring a sensor for a hard disk drive
View Patent ↗A nano-sized CPP aperture is precisely positioned to within a few nanometers of a slider ABS surface to maximize a signal from the disk and to prevent lapping damage to the aperture itself. A linear array of apertures is aligned perpendicular to the ABS plane. The head resistance is monitored during lapping. Each time an aperture is lapped through, there is an increase in head resistance that is equal to the inverse of the total aperture area. There are three equal-sized apertures that are evenly spaced apart. When the first aperture is lapped through, there is a 50% increase in resistance, and a 100% increase in resistance when the second aperture is lapped through. These resistance increases are very large and are easy to distinguish from noise.
1. A method of configuring a sensor for a hard disk drive, comprising:
(a) providing a magnetic sensor having a current-perpendicular-to-the-plane (CPP) configuration with an air bearing surface, a plurality of metallic layers, and an insulation layer between at least two of the metallic layers;
(b) forming apertures in the insulation layer and filling the apertures with an electrically conductive material;
(c) lapping the sensor at the air bearing surface;
(d) passing electrical current between the metallic layers through the apertures in the insulation layer and monitoring a resistance between the metallic layers during lapping;
(e) monitoring an increase in resistance each time one of the apertures is lapped through; and then
(f) stopping the lapping when a target resistance is achieved.
2. The method of claim 1 , wherein step (f) comprises stopping prior to lapping a final one of the apertures.
3. The method of claim 1 , wherein step (b) of forming the apertures further comprises forming a linear array of apertures that are aligned perpendicular to a plane of an air bearing surface of the sensor.
4. The method of claim 1 , wherein steps (c) though (f) comprise lapping through a third-to-last aperture and measuring a 50% increase in resistance, lapping through a second-to-last aperture and measuring a 100% increase in resistance, and the 50% and 100% increases in resistance are relatively much larger than and readily distinguishable from noise generated from a smearing of conducting materials across the insulation layer at a lapping surface of the sensor.
5. The method of claim 1 , wherein step (b) comprises forming a second-to-last aperture much larger in size than a final aperture in order to cause an even more dramatic increase in resistance when lapped.
6. The method of claim 1 , wherein step (b) comprises evenly spacing the apertures apart from each other, other than a unique spacing between a third-to-last aperture and a second-to-last aperture, so that the unique spacing is easier to recognize of a lapping position relative to the sensor and lapping is stopped at a desired location between the second-to-last aperture and a final aperture.
7. The method of claim 1 , wherein step (b) comprises lithographically-defining the apertures at a size that is equal to or less than 40 nm.
8. The method of claim 1 , wherein step (b) comprises lithographically-defining the apertures at a size that is in a range of 5 nm to 40 nm.
9. The method of claim 1 , wherein step (b) comprises positioning a final one of the apertures within a few nanometers of the air bearing surface to maximize a signal from a disk and to prevent lapping damage to the final one of the apertures.
10. The method of claim 1 , wherein step (b) comprises forming the apertures in various sizes, and spacing apart the apertures at various distances.