# US 2014/0154952 A1 · Wafer grounding design for single pad lapping

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- Number: US 2014/0154952 A1
- Document ID: US20140154952A1
- Status: Published application
- Kind: A1
- Application number: 13/690,685
- Filed: 2012-11-30
- Published: 2014-06-05
- Earliest claimed: 2012-11-30
- Assignees: HGST Netherlands B.V.
- Applicants: Hgst Netherlands B.V.
- Inventors: David P. DRUIST; Glenn P. GEE; Unal M. GURUZ; Edward H. LEE; David J. SEAGLE; Darrick T. SMITH
- Web page: https://patentgrep.com/patent/US20140154952A1

## CPC

- G11B 5/4853: {Constructional details of the electrical connection between head and arm}
- B24B 37/005: Control means for lapping machines or devices
- G11B 5/3166: {Testing or indicating in relation thereto, e.g. before the fabrication is completed}
- G11B 5/3169: {Working or finishing the interfacing surface of heads, e.g. lapping of heads}
- G11B 5/3173: {Batch fabrication, i.e. producing a plurality of head structures in one batch}
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)
- B24B: MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING (grinding of gear teeth B23F, of screw-threads B23G1/36; by electro-erosion B23H; abrasive or related blasting B24C; tools for grinding, buffing or sharpening B24D; polishing compositions C09G1/00; abrasives C09K3/14; electrolytic etching or polishing C25F3/00; grinding arrangements for use on assembled railway tracks E01B31/17); DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS

## Abstract

Embodiments described herein generally relate to connecting Electronic Lapping Guides (ELG) to a lapping controller to reduce resistance from current crowding while reducing connections to the ELG. A device and a system can include a wafer with peripheral grounding vias having a radius of at least 10 μm, a plurality of sliders with a magnetoresistive (MR) elements; a plurality of ELG electrically coupled to the lapping controller through a combination of the wafer and grounding pads and a bonding pad electrically coupled to the ELG. The ELG or the bonding pad can be positioned in the kerf or the device region of a row. If the ELG and the bonding pad are positioned in separate regions, a noble metal should be used to connect. Further, the number of grounding pads can be reduced by using grounding vias at specific intervals and specific sizes.

## Claims

### Claim 1

A device, comprising:
a wafer comprising a plurality of peripheral grounding vias for controlling current crowding, the peripheral grounding vias having a radius of at least 10 μm;
a plurality of sliders disposed on the wafer, each slider of the plurality of sliders comprising:
a magnetoresistive (MR) element configured to detect magnetic orientation changes, create magnetic orientation changes or combinations thereof in a magnetic media; and
an air bearing surface (ABS) formed proximate to the MR element;
a kerf region positioned between the plurality of sliders;
a plurality of electronic lapping guides (ELG) electrically coupled to one or more grounding vias and one or more grounding pads, the ELG configured to provide a resistance; and
a bonding pad electrically coupled to the ELG, wherein the bonding pad, the ELG, and the wafer are part of a current path permitting current to flow through the ELG.

### Claim 2 (depends on 1)

The device of claim 1, wherein the radius of the grounding vias are between 10 and 25 μm.

### Claim 3 (depends on 1)

The device of claim 1, wherein the ELG is positioned in the kerf region.

### Claim 4 (depends on 3)

The device of claim 3, wherein the ELG is electrically coupled to the bonding pad with a noble metal.

### Claim 5 (depends on 1)

The device of claim 1, wherein the plurality of ELGs alternate between electrically connecting to a grounding via and electrically connecting to a grounding pad along the wafer.

### Claim 6 (depends on 1)

The device of claim 1, wherein the peripheral grounding vias have a radius of between 10 and 20 μm.

### Claim 7 (depends on 1)

The device of claim 1, wherein the bonding pad is positioned in the kerf region.

### Claim 8

A device, comprising:
a row comprising a plurality of kerf regions and a plurality of device regions;
a magnetoresistive (MR) element disposed on the device regions and configured to detect magnetic orientation changes, create magnetic orientation changes or combinations thereof in a magnetic media;
electronic lapping guides (ELGs) electrically coupled to the wafer, the ELGs comprising:
a first internal lead connected to a bonding pad; and
a second internal lead connected to either a grounding pad or a grounding via for providing an electrical connection to the lapping controller;
one or more bonding pads electrically coupled to each of the ELGs; and
one or more peripheral grounding vias positioned outside of the device region.

### Claim 9 (depends on 8)

The device of claim 8, wherein the peripheral grounding vias have a radius of at least 10 um.

### Claim 10 (depends on 8)

The device of claim 8, wherein the grounding vias have a radius of at least 10 um.

### Claim 11 (depends on 8)

The device of claim 8, wherein at least one of the one or more bonding pads is positioned in the device region.

### Claim 12 (depends on 8)

The device of claim 8, wherein the bonding pads and the ELGs are electrically coupled using a noble metal.

### Claim 13 (depends on 8)

The device of claim 8, wherein at least 30% of the ELGs connect to a grounding via.

### Claim 14 (depends on 8)

The device of claim 8, wherein the grounding vias have an increasing radius from center to edge of the row.

### Claim 15

A system for lapping a wafer, the wafer comprising:
a plurality of slider-kerf groups, each slider-kerf group comprising:
a slider-kerf boundary dividing a slider portion from a kerf portion;
a magnetoresistive (MR) element configured to sense data stored in a magnetic media, write data to the magnetic media or combinations thereof;
an electronic lapping guide (ELG) configured to indicate, using a resistance of the ELG, a stripe height of the sensor, wherein the ELG is either electrically coupled to either the wafer through a grounding via or to the grounding pad;
a peripheral grounding via in contact with a high conductivity material, wherein at least one grounding via is formed for every slider-kerf group; and
a bonding pad electrically coupled to the ELG, providing a current path permitting current to flow to the ELG;
the system comprising:
a lapping system comprising a lapping controller and configured to simultaneously lap an air bearing surface on the plurality of sliders, wherein the wafer is configured to be mounted on the lapping system; and
the lapping controller electrically coupled to the bonding pads, the grounding pads and the peripheral grounding vias, the lapping controller configured to measure the resistance of the ELG using the current path and provide instructions to the lapping system based on the measured resistance.

### Claim 16 (depends on 15)

The system of claim 15, wherein the lapping controller measures the resistance of the ELG in a row simultaneously.

### Claim 17 (depends on 15)

The system of claim 15, wherein the bonding pad is positioned in the slider portion of the slider-kerf group.

### Claim 18 (depends on 15)

The system of claim 15, wherein the lapping system further comprises a piston corresponding to each slider-kerf group.

### Claim 19 (depends on 15)

The system of claim 15, wherein the ELG are positioned in the kerf region of the slider-kerf group.

### Claim 20 (depends on 15)

The system of claim 15, wherein the lapping controller is connected to every second ELG through the corresponding grounding pad and the peripheral grounding vias.

### Claim 21 (depends on 20)

The system of claim 20, wherein the ELG which are not connected to the ELG are connected to the wafer through the corresponding grounding via.