US 2022/0059131 A1Published application

Built-In Resistance Sensor for Measuring Slider Level Pole Width at Point "A" (PWA) for PMR/MAMR Writers

AssigneeHeadway Technologies, Inc.

InventorYan Wu

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Abstract

A PMR (perpendicular magnetic recording) write head is configured for measurements at the slider level and wafer-level processing stages that will allow a determination of the pole width at a position A (PWA) using the results of a resistance measurement between a main pole (MP) and surrounding write shields (WS) with a layer of conductor in the write gap and a layer of insulating material replacing the side gaps. Knowledge of an accurate value of PWA allows adjustments to be made in the processing of sliders on each rowbar which, in turn improves the capability of delivering the desired statistical variation (sigma) in the distribution of erasure widths for AC signals (EWACS) in a given design which, in turn, gives better overall performance in hard disk drive (HDD) applications.

Claims15

Dependent claims

A method of measuring a pole width at an arbitrary position “A” (PWA) of a trailing edge of an air bearing surface (ABS) of a magnetic pole tip of a specially configured perpendicular magnetic recording (PMR) writer or microwave assisted magnetic recording (MAMR) writer while said PMR or MAMR writer is being processed by a lapping process, said method comprising:

providing a wafer comprising a multiplicity of sliders disposed thereon;
wherein
each of said multiplicity of sliders has a writer resistive lapping guide (WRLG) sensor formed thereon, said sensor being a guide for monitoring the progress of an ongoing lapping process to which said PMR or MAMR writer is being subjected;
wherein
each said slider comprises a (PMR) or (MAMR) writer formed therein;
wherein
each said PMR or (MAMR) writer comprises a tapered magnetic pole having a trapezoidal cross-section in an air-bearing surface (ABS) plane wherein said trapezoidal cross-section has a trailing edge and a parallel leading edge and is widest at said trailing edge, having a width there at arm point “A” of said ABS, said width being denoted PWA;
wherein
each said magnetic pole is surrounded by shields from which it is separated by material-filled gaps of uniform thickness, said gaps comprising a write gap formed between said trailing edge of said magnetic pole and a trailing shield (TS) and laterally disposed mirror symmetric side gaps separating similarly symmetric side edges of said pole from laterally disposed side shields (SS);
then,
selecting a specially configured slider-mounted PMR or MAMR writer from said multiplicity of sliders in which dielectric material normally filling said write gap of said PMR writer mounted therein has been replaced with a conducting material;
and wherein a microwave generating stack fills said write gap of said MAMR writer;
and wherein
in said specially configured slider, material in said side gaps of said PMR writer having been replaced with insulating material;
and
forming a resistance measuring circuit on both said specially configured writers to measure a resistance R between said MP and said trailing shield (TS);
then, at selected stages of said lapping process,
measuring both R and values of said WRLG sensor and obtaining PWA using a formula expressing PWA in terms of said measured values of said WRLG sensor and from said measured value of R.

15 more elements

A built-in sensor for use during processing of slider-mounted PMR (perpendicular magnetic recording) or MAMR (microwave assisted magnetic recording) writers, comprising:

a slider selected from a multiplicity of sliders disposed along parallel slices in a wafer wherein each said slider comprises a perpendicular magnetic recording (PMR) writer further comprising a main magnetic pole (MP) having a trapezoidal cross-section in an air-bearing surface (ABS) plane, a write-gap (WG) formed on a trailing edge surface of said MP and extending laterally and symmetrically beyond said trailing edge surface, a trailing shield (TS) above said (WG), side gaps (SG) disposed against and contacting both lateral sides of said MP and side shields (SS) disposed on either side of said SG, wherein
said WG is filled with a conducting material;
and wherein
said SG are filled with an insulating material;
and wherein
a resistance measuring circuit is provided to measure a resistance between said MP and said TS;
whereby
a measurement of said resistance during a lapping process on said PMR or MAMR writer is used to determine a width of a trailing edge, PWA, of said MP in said ABS plane.

5 more elements

A slider-mounted perpendicular magnetic recording (PMR) writer or microwave assisted magnetic recording (MAMR) writer, comprising:

a magnetic main pole (MP) emerging at an air-bearing surface (ABS), said MP having a trapezoidal ABS face that is wider at a cross-track trailing edge surface, denoted “_A_”, said width at “_A_” being denoted PWA, than at a parallel leading edge surface and wherein said trailing and leading edge surfaces are connected by symmetrically formed side edge surfaces;
a write gap layer formed over said “_A_” surface and extending symmetrically beyond lateral edges of said “_A_” surface;
wherein
said write gap layer includes a microwave generating stack in said MAMR writer;
side gap layers formed against side edge surfaces, said side gap layers abutting undersides of said write gap layer;
wherein the value of PWA has been accurately estimated by means of a built-in electrical resistive sensor measurement taken using a corresponding neighboring slider-mounted PMR writer or a corresponding neighboring slider-mounted MAMR writer having a built-in sensor configured to produce such a measurement, whereby statistical variations in writer parameters are improved and the Erasure Width of an AC signal (EWAC) variance of said PMR writers or said MAMR writers is known within narrower limits.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application: 16/997,155Filed 19 Aug 2020
Published: 24 Feb 2022
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

G11B 5/3166
Fabrication methods or processes specially adapted for a particular head structure, e.g. using base layers for electroplating, using functional…:…
G11B 21/24
Supporting the heads; Supporting the sockets for plug-in heads: head support adjustments
G11B 5/11
Structure or manufacture of housings or shields for heads: shielding of head against electric or magnetic fields
G11B 5/314
Including layers not usually being a part of the electromagnetic transducer structure and providing additional features, e.g. for improving heat…:…