Test components fabricated with pseudo sensors used for determining the resistance of an MR sensor
View Patent ↗Test methods and components are disclosed for testing resistances of magnetoresistance (MR) sensors in read elements. Test components are fabricated on a wafer with a first test lead, a pseudo sensor, and a second test lead. The test leads and MR sensor are fabricated with similar processes as first shields, MR sensors, and second shields of read elements on the wafer. However, the pseudo sensor in the test component is fabricated with lead material (or another material having similar resistance properties) instead of an MR thin-film structure like an MR sensor. Forming the pseudo sensor from lead material causes the resistance of the pseudo sensor to be insignificant compared to the lead resistance. Thus, a resistance measurement of the test component represents the lead resistance of a read element. An accurate resistance measurement of an MR sensor in a read element may then be determined by subtracting the lead resistance.
1. A method of testing resistances of magnetoresistance (MR) sensors in read elements of magnetic recording heads on a wafer, the method comprising:
fabricating a test component on the wafer along with the magnetic recording heads, wherein the test component includes a first test lead, a second test lead, and a pseudo sensor formed from lead material instead of MR thin-films;
measuring a resistance of the test component;
measuring a total resistance of a read element fabricated on the wafer; and
determining the resistance of an MR sensor in a magnetic recording head on the wafer based on the resistance of the test component and the total resistance of the read element.
2. The method of claim 1 wherein measuring a resistance of the test component comprises:
applying a varying magnetic field; and
measuring a transfer curve of the resistance of the test component based on the varying magnetic field.
3. The method of claim 2 wherein measuring a total resistance of a read element fabricated on the wafer comprises:
measuring a transfer curve of the resistance of the read element based on the varying magnetic field.
4. The method of claim 3 wherein determining the resistance of an MR element in a magnetic recording head comprises:
determining a transfer curve of the resistance of the MR element in the magnetic recording head based on the transfer curve of the resistance of the test component and the transfer curve of the resistance of the read element.
5. The method of claim 1 wherein a plurality of test components are staggered throughout the wafer.
6. The method of claim 1 wherein measuring a total resistance of a read element fabricated on the wafer comprises:
measuring a total resistance of a read element that is fabricated in a magnetic recording head on the wafer.
7. The method of claim 1 wherein measuring a total resistance of a read element fabricated on the wafer comprises:
measuring a total resistance of a read element that is fabricated in another test component on the wafer.