WO1998000841A1

WO1998000841A1 - Virtual contact hard disk drive with planar transducer

Info

Publication number: WO1998000841A1
Application number: PCT/US1997/011408
Authority: WO
Inventors: Robert Hempstead; Keith R. Berding; William C. Cain; Harold J. Hamilton; Darren T. Imai; Dimitre A. Latev; Mark A. Lauer; Michael E. Mcaleavey; Alexander P. Payne; David D. Roberts
Original assignee: Censtor Corporation
Priority date: 1996-06-28
Filing date: 1997-06-26
Publication date: 1998-01-08

Abstract

A disk drive slider (20) having a planar transducer (46) in virtual contact with a spinning rigid disk (50) during information storage and retrieval has a substrate and a strata formed on a disk-facing side of the substrate including a transducer (46), air-bearing side pads (25, 28) and a trailing central pad (30). The transducer has a pair of pole tips (44) exposed in a trailing portion of the trailing central pad (30). During operation the slider (20) tilts slightly so as to place the pole tips (44) in closer proximity to the disk surface (48) than the trailing end (35) of the slider (20). The disk-contacting pads (25, 28), with the exception of the minute poletip region, are composed of amorphous, diamond-like carbon. The transducer (46) contains a magnetic circuit that is mostly planar but has sloped regions in order to form a highly efficient, magnetically permeable loop.

Description

VIRTUAL CONTACT HARD DISK DRIVE WITH PLANAR TRANSDUCER

Technical Field

The present invention relates to disk drives having transducers in close proximity

to the disk surface during reading or writing.

Background of the Invention

Hard disk drives have traditionally employed transducers designed to be slightly

spaced from the rapidly spinning rigid disk surface by an air-bearing accompanying the

surface. In order to maintain this spacing the transducer is typically appended to the back

of a much larger, aerodynamic "slider" which is designed to interact with the air-bearing

so that the essentially stationary head "flies" over the spinning disk. Though this

separation serves the purpose of avoiding wear of the head and the disk, it also reduces

resolution of signal communication between the transducer and the media. To increase

data storage density, the air separation between the transducer and the media has

generally decreased over many years of development in the magnetic storage industry. However, a smaller separation generally increases the probability of impact between the

head and the disk during operation of the disk drive system, which may result in

destruction of the disk drive and loss of stored information.

Instead of completely separating from the disk. U.S. Pat. No. 4.901.185. to Kubo

et al. discloses a slider designed to operate with a leading edge lifted b> the air layer that

accompanies the spinning disk while a trailing edge contacts the disk, the slider holding a

transducer designed for perpendicular recording. To avoid destructive wear and to minimize variations in the head-disk separation the head is mounted on the trailing edge

of the tail dragging slider so that a constant spacing between the head and the disk is

maintained. Rather than maintaining a constant separation between the head and media, a

further reduction in head-media separation is achieved in commonly assigned U.S. Pat.

No. 5,041 ,932 to Hamilton, in which a thin-film slider has a disk-facing projection

encompassing a pole and contacting the disk surface. Similarly, in U.S. Pat. No.

5,327,310, Bischoff et al. teach a single rail slider having a transducer formed on a tail-

dragging end, and U.S. Pat. No. 5.473,485 to Leung et al. discloses a tripad slider having

a transducer formed on a tail-dragging end pad while leading pads remain aloft.

The Bischoff and Leung patents have transducers formed on the trailing,

essentially vertical ends of the sliders in a series of thin, mostly vertical films with

poletips next to the tail-dragging corner so that the spacing between the poletips and

media is reduced. Also known are planar transducers, in which the thin films extend

mostly parallel to the disk surface, and which may have electromagnetic advantages for

structures in which the thin transducer layers extend symmetrically about the poletips as

well as parallel to the disk. A planar transducer incorporated in a slider designed for

continuously sliding on a hard disk recording surface is disclosed in commonly assigned

U.S. Pat. App. Ser. No. 08/528,890 filed September 15, 1995, for a CONTACT

PLANAR RING HEAD, which is hereby incorporated by reference. Continuously

sliding on a hard disk surface, however, leads to wear of the transducer which is

impossible to predict with perfect accuracy. Moreover, planar transducers preclude the

location of the poletips adjacent to a trailing corner of a slider due to the horizontal extension of the other transducer layers well beyond the poletips. Since the poletips of a

planar transducer must be spaced from the trailing corner, sliding that corner on the disk

by tilting the rest of the slider upward would tend to increase rather than decrease the

head-media spacing.

An object of the present invention is to combine the efficiency of a planar head

with reduced head to media spacing and wear provided by partial slider contact with the

disk.

Summary of the Invention

The above object is achieved in a hard disk drive having a planar transducer

located near a trailing corner of a disk-facing side of a slider, with the transducer

asymmetrically encased by a contact pad so that a pair of poletips are centrally disposed

relative to the transducer yet adjacent to the trailing, disk-contacting end of the pad. The

operational tilt of the slider is sufficiently slight compared to the height of the pad that the

trailing end of the pad contacts the disk while the trailing corner of the slider remains

spaced from the disk. A pair of air-bearing side pads are located on the disk-facing side

of the slider ahead of the laterally centered trailing pad. the side pads providing the lift

and tilt that separates most of the slider from the rapidly spinning hard disk, with a

tailored step or ramp at the front end of the side pads initially lifting and lilting the slider

as the disk gains speed.

The slider is formed, along with thousands of other sliders, by deposition and

patterning of thin-film layers to form thousands of planar transducers on a wafer substrate, which is thereupon diced into individual sliders each comprising a wafer die

and an adjoining thin-film strata. Prior to formation of the strata the substrate is pierced

with multiple vias which are filled with conductive metal such as gold or copper to

provide electrical leads to the transducers. An extra metal layer may be formed between

the substrate and the strata to provide for thermal expansion and contraction of the

substrate due to later metal bonding of the leads on the side of the substrate opposite the

strata, in order to favorably control the curvature of the slider. Alternatively, a layer of

metal may be formed on the strata side of the substrate to control substrate crown and

provide leads for the transducer. Thermal expansion matching of the wafer with the strata

may also be accomplished by having both the wafer and the strata formed primarily of the

same iπsulative material, preferably alumina. Unlike conventional sliders, the strata

covers most of a disk-facing surface of the substrate and is etched to create a plurality of

projections which interact with the air-bearing to bring the poletips into virtual contact

with the disk surface during read-write communication. Etching of the strata allows

precise tailoring of the aerodynamic disk-facing surfaces while they are still attached to

the wafer, providing an efficient, mass production operation that is less costly and more

precise than traditional abrasive feathering and faceting. Reactive ion etching (RIE) is

primarily used for sculpting the disk-facing surface, as it is faster and more cost effective

than other approaches, although ion beam etching (IBE) may be employed for features of

about one micron or less.

The central pad and the side pads, aside from the poletips and a submicron,

amagnetic gap between the poletips. are composed of amorphous diamond-like carbon (DLC). which provides a superior material for interaction with the disk surface. The disk

surface is also preferably composed primarily of carbon, including a hard carbon overcoat

that may be hydrogenated or nitrogenated. and a hydrocarbon or fluorocarbon lubricant

distributed on the overcoat. The interaction of a slider surface, disk surface and lubricant

all containing significant fractions of carbon based compounds has been found to exhibit

superlative long-term wear characteristics, perhaps due to the comparably high hardness

of the disk and slider surfaces, perhaps due to the probability of combustion rather than

abrasive wear of those materials combinations or perhaps due to a similar dearth of

deleterious chemical byproducts of this slider, disk and lubricant combination.

The planar transducer is also constructed to allow for a microscopic amount of

wear of the poletips from dynamic contact with the disk surface to occur over a drive

lifetime without harming transducer performance. In contrast with vertical transducers

which have magnetic yokes that approach each other at a small angle to form poletips, so

that wear of those poletips leads to bleeding of tlux across the closely spaced yokes, the

planar transducer of the present invention has yokes which approach each other at a large

angle, affording several microns of poletip wear without causing magnetic saturation or

bleeding. Stated differently, a much larger variation in poletip throat height is afforded

by the planar transducer than in a vertical transducer, the throat height variation allowing

for both wear and manufacturing tolerances. The present invention similarly contrasts

with prior art planar transducers having a shunt which would divert increased flux as

poletips wear. At least one of the magnetic yokes is formed as a gently curving layer to form a

highly efficient magnetic loop that may resemble the shape of a clamshell, half clamshell,

terrace or other formations. A high magnetic saturation layer may be formed adjoining

the writing or trailing side of the gap between the poletips to avoid saturation at the

writing edge, such a high Bs layer optionally formed along the leading edge as well.

Additionally, the magnetic yoke is constructed so as to saturate elsewhere in the magnetic

circuit, effectively choking off poletip saturation. A magnetoresistive (MR) element may

be coupled to the yoke distal to the poletips for reading signals, sufficiently removed

from disk contact to avoid noise from thermal asperities.

Brief Description of the Drawings

FIG. I is a bottom view of a disk-facing side of a virtual contact slider of the

present invention.

FIG. 2 is a side view of the slider of FIG. 1 , operating with the poletips of the

slider in virtual contact with a magnetic recording surface of a rigid disk.

FIG. 3 is a bottom view of a disk-facing side of a negative pressure virtual contact

slider of the present invention.

FIG. 4 is a bottom view of a disk-facing side of a virtual contact slider of the

present invention having a shelf adjoining separate curved side rails.

FIG. 5 A is a perspective view of a wafer used for the construction of thousands of

sliders of FIG. 1 , the wafer pierced with conductive leads and having an adjoining metal

film. FIG. 5B is a perspective view of a wafer used for the construction of thousands of

sliders of FIG. I , the wafer sandwiched with thermally compensating metal layers.

FIG. 6 is a cross-sectional view of some initial steps in constructing a planar

transducer on a portion of the wafer substrate, including the formation of a first yoke

layer and a first coil layer.

FIG. 7 is a top view of the planar transducer of FIG. 6.

FIG. 8 is a cross -sect ion a I view of some subsequent steps in constructing the

planar transducer of FIG. 6, including the formation of a second yoke layer and a second

coil layer.

FIG. 9 is a cross-sectional view of the construction of a pedestal that elevates the

second yoke layer.

FIG. 10 is a cross-sectional view of the formation of a pair of pole layers

separated by an amagnetic gap layer atop the second yoke layer.

FIG. 1 1 is a cross-sectional view of the etching of the pole layers of FIG. 10 into a

pair of poletips.

FIG. 12 is a top view of the etching poletips of FIG. 1 1.

FIG. 13 is a cross-sectional view of the construction of a DLC pad encasing the

poletips and asymmetrically disposed over the planar transducer of FIG. 12.

FIG. 14 is a top view of a disk-facing side of a wafer with an array of sliders to be

cut into rows for lapping of ramps.

FIG. 15 is a top view of a disk-facing side of a wafer with an array of sliders

covered by a nickel-iron mask for angled reactive ion etching of ramps. FIG. 16 is a cross-sectional view of an angled, rotating etching of a DLC pad to

form sloping ramps along borders of the pad.

FIG. 17 is a top view of some initial steps in the construction of a

magnetoresistive embodiment of the invention.

FIG. 18 is a cross-sectional view of some additional steps in the construction of

the magnetoresistive embodiment of FIG. 17.

FIG. 19 is a cross-sectional view of the magnetoresistive embodiment of FIGs. 17

and 18 asymmetrically covered by a trailing pad of FIGs. 1 -4.

Description of the Invention

Referring now to FIG. 1. a slider 20 is shown from a perspective displaying a

disk-facing surface 22, which includes a pair of laterally disposed pads or rails 25 and 28,

and a centrally disposed trailing pad 30. The slider 20 is designed to interact with a

relatively moving hard disk surface such that a leading end 33 of the slider generally

encounters a portion of the surface ahead of a trailing end 35. The pads 25. 28 and 30

protrude from a generally recessed area 32 separating the pads. A pair of ramps or steps

38 and 40 arc located near the leading end of the pads 25 and 28, respectively, in order to

provide an aerodynamic lift to the leading end 33 of the slider from an air-bearing that

accompanies a rapidly spinning disk. A pair of poletips 44 are exposed on a trailing edge

of the trailing central pad 30. The poletips 44 project from near the center of a planar

transducer region 46 which is formed within the surface 22 and asymmetrically covered

by pad 30. As shown in FIG. 2, the slider is operationally positioned adjacent to a magnetic

recording surface 48 of a rigid disk 50 which is spinning at several thousand RPM. with a

portion of the disk adjacent to the slider traveling in a direction indicated by arrow 52.

An air layer which accompanies the rapidly spinning disk 50 interacts with ramps 38 and

40 to lift the leading end 33 of the slider compared to the trailing end 35. which is

adjoined by the recessed area 32, so that the slider is tilted relative to the disk surface 48.

Having the trailing central pad 30 asymmetrically covering a leading half of the

transducer region 46 with the poletips 44 exposed near the trailing end of the pad allows

the poletips to be closer to the disk 50 than the remainder of the tilted, disk-facing surface

32, providing virtual contact between the poletips and the disk surface 48, significantly

enhancing reading and writing resolution compared with traditional flying heads. The

poletips 44 are encased by the DLC pad 30 on a trailing side as well as a leading side to

avert damage from contact with the disk 50, and as explained in more detail below, the

pad and poletips are designed to afford a limited amount of wear consistent with a

required drive lifetime. The slider 20 is held by gimbal flexure members 53 which are

attached to a free end of an elongated load beam 57 which is mounted at an opposite end

to a rotary actuator, not shown.

The slider shown in FIG. I may have a disk facing surface which extends laterally

about 1 mm and longitudinally about 1.25 mm. although variations from these figures are

easily envisioned. In particular, smaller sliders having a mass of less than 2 mg are

believed to have advantages in reducing wear and spacing. The pads 25 and 28 may each

have a disk-facing area of about 0.2 mm , while the trailing pad may have a disk-facing area of about 0.013 mm^", although these figures may vary significantly. The disk-facing

portions of pads 25, 28 and 30 are generally coplanar and have an elevation that differs

from the recessed area 32 by about 10 μm, although the elevation may range from this

figure by a factor of two. The transducer region 46 may have a shallower recess than the

remainder of recessed area 32 in order to protect the transducer while allowing the

poletips 44 to protrude toward the disk. The ramps or steps 38 and 40 have an elevation

that differs from that of the pads 25 and 28 by less than about 1 μm, and typically about

1/4 μm. Ramps 38 and 40 may be formed by lapping, while an alternate embodiment

having steps 38 and 40 may be formed by 1BE. RIE is typically used to form the deeper

recess 32.

FIG. 3 shows a slider 55 having a contoured disk-facing surface 58 formed by

patterning and etching the thick DLC coating that forms most of that surface. In this

embodiment, the slider 55 has a single, generally U-shaped lifting pad 60 and a trailing

central pad 62. Etching of the disk-facing surface allows the formation of curves that are

strong, aerodynamical I y favorable and averse to debris collection, but which may not be

economically feasible with micromachining processes such as sawing and lapping. For

example, the trailing central pad 62 has a generally oblong shape, with a flat trailing edge

portion adjacent to a pair of poletips 64. so that sufficient DLC encases the rear corners of

the poletips to ensure against chipping at the corners, without extending excessively

directly behind the poletips so as to hold the poletips away from the disk surface while

tilted during operation. Similarly, the smoothly U-shaped curve of pad 60 allows the

slider 55 to be skewed relative to the flow of air from the disk, as is common with sliders positioned by a pivoting, rotary actuator, without significantly altering the upward tilt of

the leading end 66 compared to the trailing end 68. The oblong shape of the pad 62 also

helps to avoid changes in load or tilt due to skew, as well as minimizing collection of

harmful debris. Moreover, the smooth curves of the disk-facing surface 58 generally

reduce turbulence in the flow of the air layer as interacting with the slider, which helps to

avoid vibration and other problems. The pads 60 and 62 differ in elevation from recessed

area 72 by about 1 μm to 3 μm, while the optional step 70 has an elevation that differs

from the pads by between 1/10 μm and 1 μm.

With pads 60 and 62 covered by a mask, an RIE or IBE is performed that results

in mostly perpendicular contoured borders between the pads 60 and 62 and a recessed

negative pressure region 72. Either before or after the creation of negative pressure

region 72, a shallower, curving ramp or step 70 may be formed by etching of the leading

edge of the pad 60, the step or ramp 70 optionally extending to the leading edge 66, while

the remainder of the disk-facing surface 58 is covered by a mask. A planar transducer

region 75 similar to that described with reference to FIG. I is symmetrically disposed

adjacent to the exposed poletips 64 within the body of the slider. The disk-facing surface

of the pad 62 provides a measured amount of aerodynamic lift in the midst of the negative

pressure region 72, so that the poletips 64 are slightly cushioned from the rigid disk

surface, allowing virtual contact without excessive wear.

FIG. 4 shows a slider 77 that has a pair of curved, air-bearing side pads 79 and 80

and a generally elliptical central pad 82, all of which are formed primarily of DLC. The

central pad 82 encompasses a pair of poletips 85 which protrude from the center of a

I I planar transducer 88, but which are asymmetrically oriented relative to the central pad.

The DLC of the disk facing surface of this embodiment has been etched to form a step 90

adjoining pads 79 and 80 having a height between that of the pads 79. 80 and 82 and a

recessed area 92. The pads 79, 80 and 82 may have a height of between 1 μm and 5 μm

above the recessed area 92, while the step 90 may have an elevation in a range between

0.05 μm and 2 μm different from the pads. As with the embodiment previously

described, the curving borders of the pads and step 92 present relatively smooth surfaces

for interaction with the air and any solid or liquid asperities accompanying the spinning

disk surface. Also in keeping with the previous embodiments, the pad 82 encasing the

poletips has a trailing edge which extends only about 10 μm behind the poletips. although

this extension may range from less than 5 μm to more than 20 μm, so that little spacing

between the poletips and the media is caused by the tilt of the slider. Moreover, the tilt

induced spacing may not exist for the situation in which the trailing edge oflhe pad 82

has been burnished or worn.

Also in keeping with the previous embodiments, the disk-contacting pads 79. 80

and 82 of the slider 77 are almost entirely formed of DLC, which has a particular

combination of attributes not found in prior art sliders. First, the DLC layer that forms

the pads 79. 80 and 82 is hard yet amorphous, so that it is resistant to chipping as well as

microscopic wear. The DLC layer has been constructed, as will be described below, in a

manner reducing defect or bias lines along which cracks tend to propagate, including

reducing or eliminating such defects adjacent to the poletips 82, where the defects would

otherwise be most common and most troublesome. Etching the DLC layer to form smooth, low stress curves is afforded by the amorphous structure of that layer, again

contrasting with crystalline or polycrystalline forms of carbon or silicon employed in

prior art sliders. The DLC layer is primarily formed of carbon, although the DLC may

contain fractions of hydrogen, nitrogen and/or fluorine carbon as well, and has a mix of

sp and sp bonds which, on a larger scale, are found in diamond and graphite, for

example. Although ideally no wear would occur to a disk-slider interface, realistically

some wear must be tolerated, whether due to start-stop contact for flying sliders or

continuous sliding for contact drives, or some combination of operational and transitional

wear. The DLC disk-contacting pads of the present invention are particularly suited for

operating in combination with a disk having a hard, carbon-based overcoat and carbon-

based lubricants, both in terms of substantially matching the hardness of the disk surface and pads and in chemically matching the disk, overcoat and lubricant to allow

combustion that lacks destructive byproducts. Preferably the disk overcoat contains

hydrogenated or nitrogenated carbon of a hardness matched to that of the slider pads,

while the lubricant preferably includes hydrocarbons or fluorocarbons. The resulting

carbon-based interface demonstrates superlative freedom from wear and contaminants,

unlike conventional sliders having mostly aluminum-oxide titanium-carbide, silicon or

alumina disk-contacting surfaces.

A process for making the planar, virtual contact slider of the present invention is

shown beginning with FIG. 5A. in which a wafer substrate 100 typically four to ten

inches across and used for forming thousands of such sliders is pierced with a number of

through holes 102, at least two such holes being formed for each slider. For the situation in which the transducer has a magnetoresistive read element, an additional pair of holes is

preferably formed for each transducer to provide leads to that element separate from the

writing leads. The wafer 100 is preferably composed of pressed and sintered alumina

(AL₂O ) for matching to a primary component of the thin film transducer layers of the

sliders, but may alternatively be formed of other known wafer materials, such as silicon

(Si), silicon nitride (Si₃N₄), silicon carbide (SiC) or aluminum titanium carbide (AITiC).

The holes are formed by patterning masks and etching or laser ablating to remove

substrate material, both removal processes allowing the mass production of perforated

wafers. For the situation in which the wafer is composed of a conductive material, such

as silicon carbide, an insulative oxide or nitride coating is then formed. The holes 102 are

then filled with conductive material for electrical connections between the transducer and

leads attached to a slider suspension for connection to disk drive electronics. The

conductive material, preferably copper or gold, is deposited in and about the holes 102 by

electroplating for example, optionally leaving a thin film layer 105 on what is to be a

disk-facing side of the wafer for thermal expansion matching of metal lead bonds to be

formed on an opposite side of the wafer. The disk-facing side of the substrate is then

polished flat, and the optional metal layer 105 is etched to remove portions of it from a

transducer formation area and to disconnect the layer 105 from the conductive material

filling the holes 102.

In an alternate embodiment shown in FIG. 5B, a pair of metal layers 95 and 96 are

joined to both major surfaces of a wafer substrate 98 to form a sandwich which is

balanced against thermal expansion or contraction which would warp the wafer, while at the same time providing an overall thermal expansion coefficient that is designed to

match that of the disk-facing strata that will adjoin the sandwich. The layers 95 and 96

are generally equal in materials and dimensions, and may for example be formed of

sputtered and/or electroplated aluminum, copper, steel or titanium of a thickness of about

1/10 mil on a pressed alumina wafer having a thickness of about 10 mils, the exact

relative thicknesses being tailored to match the thermal expansion coefficient of the

strata. The layer 95 may thereafter be bonded to or formed into part of a gimbal

suspension for the slider. With this matching of the thermal expansion of the strata to a

warp-free wafer sandwich, extremely tight tolerances in slider crown can be maintained

over temperature variations of tens of degrees Celsius.

Moreover, the metal layer 96 between the substrate 98 and the strata can be

patterned to provide electrical leads for the transducer, alleviating the need to pierce the

wafer, with the opposite metal layer 95 also optionally being patterned for expansion

matching. The electrical leads exposed at an edge of a slider can be bonded to wire leads,

in a manner similar to conventional electrical connection of sliders. Moreover, instead of

initially creating a thermal expansion balanced sandwich as described above, a metal

thermal compensation layer may be glued or otherwise adhered to the surface of the slider

facing away from the disk after completing formation of the transducer. Such a metal

layer is bonded to the slider near a common slider operation temperature rather than an

elevated temperature, and constructed to essentially cancel any warping of the slider over

an operating temperature range of, for example, between 0° C and 60° C. This metal

layer may also extend to form part of the suspension for the slider, and may be patterned to form gimbal members, the gimbal members optionally being connected to the

transducer leads so as to carry signals between the transducer and the drive electronics.

Referring now to FIGs. 6 and 7, which focus on the formation of a single

transducer on the wafer substrate 100 of FIG. 5A with a lead 107 traversing the substrate

through one of the holes 102, but without the optional metal layer 105. In order to form

an efficient magnetic circuit, a plateau 1 12 may be formed by a variety of methods of

which an example involving chemical etching will now be described. An etch-stop layer

1 10 of SiC having a thickness of about 4000 A is formed on the substrate. A layer of

alumina which is to form the plateau 1 12 having a thickness of about 8 μm - 12 μm is

then sputtered, atop of which a stressed, high bias layer of alumina about 0.5 μm thick is

optionally formed, which etches faster than the thick alumina layer. This etching is

performed by first depositing a metal etch mask of MoNiFe to a thickness of about 500 A,

on top of which a layer of photoresist is applied and patterned. Exposed areas of the

MoNiFe are then removed and the resist is hardbaked for rigidity, leaving a rectangular

area protecting the top of the plateau 1 12. The approximately 1 μm thick layer of

alumina is then chemically etched with a solution of I IF diluted to 15% by volume,

although other chemical etchants may be alternatively employed, until the SiC layer 1 10

is exposed, leaving the plateau 1 12 having substantially symmetrical sides that slope at an

angle of 30° to 60°. The photoresist and metal mask fall from the plateau and are

removed once the bias layer has completely disintegrated. A reactive ion etch preferably

utilizing a CF₄/O₂ plasma is then employed to remove the SiC etch stop layer 1 10 in the

area where a magnetic yoke 1 15 is to be formed and for separating the conductive etch stop layer at edge 103 from an electrical lead 106. A mask then covers the etch stop and

extends beyond edge 103 to define conductor 106 by electroplating.

A bottom yoke layer 1 15 for the transducer is then formed of plated permalloy

atop a sputtered seed layer by window frame plating, the yoke extending at both ends.

only one of which is shown in this figure, to the top of the plateau 1 12 for joining with

ends of another yoke which has not yet been formed. A layer of photoresist 1 17 is then

deposited and patterned to remove resist above the plateau 1 12, yoke 1 15 and lead 107,

the resist 1 17 then being baked, which causes it to flow slightly and then harden, resulting

in a hard, insulative layer generally equal in elevation to the yoke layer 1 15. A second

photoresist layer 1 19 is then deposited and removed from atop the plateau 1 12 and an end

of lead 106 and then hard baked to form an insulation atop most of the yoke 1 15.

A NiFeMo or Ti/Cu seed layer is then sputtered, then covered with another

photoresist layer which is patterned with a pair of spirals, and then electroplated with

copper to form a first coil layer 122 which is connected with the conductor 106. The

patterned spiral resist is then removed as is the seed layer between coils, to leave the coil

layer 122 which are shown most clearly in FIG. 7.

Referring now to FIG. 8. subsequent steps in the formation of the transducer begin

with the photoresist patterning and electroplating of a coil connective stud 123 atop an

inner ring of coil 122, the stud providing an electrical lead between the coil layer 122 and

a second coil layer 130. Deposition of a layer 125 of alumina on and about the coil 122

and stud 123 follows, the alumina then being polished to flatten and expose the end of the

yoke disposed over raised area 1 12 and stud 123. An etch-stop layer 127 of SiC is then deposited to cover alumina layer 125, masked and patterned by IBE to remain atop the

sides of the plateau 1 12. for protection during etching of another set of sloping sides for a

top yoke 140. Another coil layer 130 is then formed by electroplating and patterning and

connected to stud 123 and a similar stud on the opposite side of the coil layer, not shown,

and is then covered with insulative alumina layer 133 which is lapped flat.

Referring additionally to FIG. 9, yet another etch-stop layer 135 of SiC is

sputtered atop alumina layer 133, after which another alumina layer is formed on top of

etch-stop 135, the alumina layer polished and covered with a MoNiFe cap (as described

regarding plateau 1 12) over the middle of yoke 1 15, so that isotropic etching of that

alumina forms a pedestal 137 having sloping sides, after which the etch stop 135 not

covered by pedestal 137 is removed. Apertures in a photoresist are then formed over the ends of yoke 1 15, allowing another etch to produce sloping sides of alumina layer 133

adjacent to the ends of yoke 1 15 and above etch stop 127. This etch stop 127 is then

removed from the bottom between the sloping sides by IBE or RIE. A second

magnetically permeable yoke 140 of NiFe is then formed by window frame plating, the

sloping sides of layer 133 allowing the ends of yoke 140 to adjoin the ends of yoke 1 15.

forming a planar, clamshell-shaped loop of magnetically permeable material with a pair

of coil layers spiral ing around both ends of the loop.

In FIG. 10, another layer 144 of alumina has been deposited and lapped flat, the

lapping also removing the peak of yoke 140 and thereby forming a gap in that yoke. A

first pole layer 146 of NiFe is then formed by window frame plating of permalloy or other

magnetically permeable material, leaving an essentially vertical edge disposed over the gap in the yoke 140. A layer 150 of amagnetic material such as hydrogenated carbon,

SiC or Si is then deposited, which has an essentially vertical section 152 formed on the

edge of which will become an amagnetic gap between the poletips. Although the section

152 of amagnetic material that will become the gap is formed on an essentially vertical

side of the pole layer 146 that is at least several microns in height, a uniform thickness of

section 152 is formed by sputtering in a vacuum chamber while positioning the platform

holding the wafer on which the transducers are being formed such that the sputtered

material impinges the gap side of the pole layer 146 as well as the top of that layer. This

uniform formation on a vertical edge can be accomplished by rotating or transporting the

wafer across the base of the sputtering chamber, or simply by positioning the wafer at a

location at which the sputtering material has an angled approach. The layer 150 is then

masked with a photoresist layer that has been patterned so that etching with IBE along the

mask edge leaves the vertical section 152 above the pedestal, but removes the portion of

the amagnetic layer 150 that had been adjoining the yoke 140. Optionally, either

immediately before or after the formation of amagnetic layer 150, a similarly formed

layer of high magnetic saturation material such as FeAl(N) may be formed for allowing high flux transmission along the trailing side of the gap 152, while a similar high B_s layer

may be formed along the leading side of that gap. After removal of the photoresist layer

that had defined the termination of layer 150, a second pole layer 155 is formed by

window frame plating or sheet plating covering amagnetic layer 150 and alumina layer

144. The amagnetic layer 150 and the portion of the second pole layer 155 that was

plated on top of the first pole layer 146 are then removed by lapping, for which layer 150 may serve as a lap-stop, to leave a planar surface 157 including the first and second pole

layers 146 and 155 and the vertical amagnetic gap 152, as shown in FIG. 1 1. The

dimensions of the vertical gap 152 that face a disk will set the magnetic resolution during

communication between the transducer and the disk, the width of the gap 1 52 being

uniform and typically between about 0.05 μm and 0.4 μm, and preferably about 0.26 μm

currently.

Referring now additionally to FIG. 12, a photoresist mask 160 has been formed in

an elongated hexagonal shape desired for a pair of poletips 164 and 166. however, the

mask 160 is larger than the eventual poletip area, to compensate for removal of a portion

of the mask during etching. The etching is done by IBE with the ion beam directed at a preselected angle α to the surface of the pole layers 146 and 155, while the wafer is

rotated, in order to form vertical sides of the poletips 164 and 166. This angled, rotating

IBE also forms a tapered skirt 168 of the poletips 164 and 166, the skirt 168 acting as an

aid to the subsequent formation of the DLC that will surround the poletips. since the absence of an acute, shadowed corner mitigates formation of weakened regions in the

DLC which tend to crack. The vertical sides of the poletips 164 and 166 allows

operational wear of the poletips to occur without changing the magnetic track width of

the head. On the other hand, the skirt 168 allows the DLC that wraps around the poletips

164 and 166 to be formed without cracks or gaps which can occur, for example, in

depositing DLC by plasma enhanced chemical vapor deposition (PECVD) onto a

vertically etched pair of poletips. Although this tapered skirt 168 can be achieved by a variety of techniques, an angled, rotating IBE is preferred that exactingly tailors both the

vertical poletips 164 and 166 and tapered skirts 168.

As shown in FIG. 1 1 , the photoresist mask 160 has an etch rate that is similar to

that of the NiFe pole layers 146 and 155, so that when the angle is approximately 45°

the pole layer 155 and the mask 160 are etched a similar amount, as shown by dashed line

170. Pole layer 146, however, is partially shielded from the angled IBE by the mask 160,

so that a portion of layer 146 that is adjacent to the mask is not etched, while another

portion is etched as shown by dashed line 172. As the wafer substrate is rotated during

etching, layer 155 will have a non-etched portion adjacent to an opposite end of the

elongated mask 160, as will areas adjacent to the sides of the elongated mask. The angle

α may be changed to further control the shaping of the poletips 44. for example to

employ a greater angle such as about 60° toward the end of the IBE. This rotating,

angled IBE is continued for an appropriate time to create a pair of poletips 164 and 166

having vertical sides with a tapered skirt 168 and a flat, elongated hexagonal top centered

about the gap 152.

The wafer and multiple transducers are then ready for the formation of the

aerodynamic disk-facing surface of each slider, including features such as the side pads

25 and 28, and trailing pad 30 as shown in Fig. 13, which focuses on the trailing pad 30

for clarity. An adhesion layer 180 of Si is deposited to a thickness of about 1000 A atop

the poletips 164 and 166 and alumina layer 144. A layer 182 of DLC is then deposited by

PECVD onto the adhesion layer 180. An approximately 1500 A thick layer 185 of NiFe

is then sputter deposited, which is then patterned by IBE with a lithographically defined photoresist mask 188 to leave, after IBE, a NiFe mask 1 0 disposed over the DLC

covered poletips 164 and 166 and asymmetrically covering the yoke 140 for defining the

trailing pad 30, and the side pads 25 and 28, not shown in this figure. The DLC layer 182

covered with the NiFe masks is then RIE etched along edges 192 with O₂ plasma to leave

projections of DLC that form the side pads 25. 28 and trailing pad 30, with the side pads

28 and 30 extending to the leading end 33 of each slider on the wafer at this point in the

process. The pads 25, 28 and 30 are then lapped to expose the poletips 164 and 166.

Alternatively, the DLC may be lapped prior to the formation of the pads 25, 28

and 30, particularly for the formation of very slight pads having an elevation of less than 5 μm, which may be formed by IBE, in order to more accurately create the aerodynamic surface. For the converse situation in which it is desirable for the pads 25, 28 and 30 to

project further than the thickness of the DLC layer, the IBE can be performed for a longer time while the pads are protected by a mask, resulting in taller, optionally tapered pads. FIG. 14 shows a view of the disk-facing surface of the wafer, in which side pads

25 and 28 of neighboring sliders are slightly spaced at leading and side edges before

separation by sawing, laser ablating or chemical/laser ablation along leading cuts 1 5 and

trailing cuts 199 to form rows of slider bars. The leading ends of pads 25 and 28, also slightly spaced between adjoining sliders, are then lapped to form the shallow angle ramp

38 shown in FIG. I and FIG. 2. The bars of slider rows are then separated into individual

sliders along divisions 200. The sliders are then bonded onto known suspensions for use in a hard disk drive. An alternative to the row-bar lapping formation of the ramps 38 and 40 described

immediately above is shown in FIG. 15, in which those ramps are formed by etching

before the sliders have been cut from each other. In this embodiment, the leading ends of

the sliders may all face in the same direction, rather than in the mirrored rows of leading

ends shown in FIG. 14. After formation of the pads 25, 28 and 30 as described above, an

etching mask is then formed that covers all but the leading ends of pads 25 and 28 for

etching of the ramps. The etching mask may be a photoresist or may be formed by

sputtering a layer of silicon or silicon dioxide that cover the wafer followed by a similarly

distributed nickel-iron layer, and then patterning a photoresist to leave the NiFe exposed

above the ramp areas, where it is removed by IBE. An angled IBE is then performed as

depicted by arrows 202, in order to form the angled ramps 38 and 40. The NiFe mask is

then removed by IBE, with the poletips 44 protected by the silicon layer, that layer being

subsequently removed by RIE etch using CF₄/0₂.

A more cost effective method for forming the features near the leading end of the

slider that generate the initial liftoff of the leading end as the disk accelerates is to simply

form steps rather than ramps, which may be formed by IBE or RIE. like step 90 of FIG. 4.

For lift at the leading end of a slider, such a step should extend from the leading end

much further than the drop in height between the step and the adjoining pad, to create a

similar aerodynamic effect as a shallow ramp. Such steps may have an elevation offset

from the pads 25 and 28 by as little as 0.05 μm or as much as about 1.0 μm, and extend

from the pads toward the leading end by as much or more than ten times that offset.

Similar to the above-described creation of an etched ramp, an angled IBE can be performed with a greater part of the leading end of the ramp exposed, to create a

combined step and ramp. After formation of the steps or ramps 38 and 40, the sliders are

separated from each other along cuts 205 and divisions 208 by sawing, laser ablating or

chemical/laser ablation.

FIG. 16 details the creation of steps or ramps on the leading, inner or outer edges

of side pads, which has particular benefit to forming such ramps or steps on curving pads,

such as pads 60, 79 and 80 of FIG. 3 and FIG. 4. After the essentially vertical IBE or

RIE etching and pole-exposing lapping of DLC to define a slider pad 210 as described

above, a silicon layer 212 is sputtered atop the wafer to protect the poletips, which are not

shown in this figure, followed by a nickel-iron layer 215. Atop the NiFe layer 215 a

photoresist, not shown, is patterned to leave openings over leading edge 217 of the pad

210, so that a vertical IBE removes the NiFe layer to expose that edge. An IBE etch may

be directed at an angle to the flat top of edge 217 as depicted by arrows 222, resulting in a

shallow sloping ramp 225 at that leading edge. Alternatively, to create an essentially

horizontal step rather than a sloping ramp, such as step 90 of FIG. 4. a vertical IBE or

RIE etch using O₂ plasma may be employed for a limited time, so that the step has a

height somewhat less than that of the pad.

FIG. 17 shows an embodiment of the virtual contact slider with a

magnetoresistive (MR) sensor piggybacking a magnetic terraced or clamshell-shaped

loop of a transducer much like that previously described, the MR sensing transducer

being employed in place of the purely inductive transducer in any of the previous

examples. MR sensor 250 and first yoke layer sections 253 and 255 of the magnetic loop are shown in FIG. 17 as they appear during construction of the yoke prior to the

formation of the coil layer. The MR stripe 250 is formed first, atop either an insulative

layer such as polished alumina or silicon nitride or directly upon a wafer formed of an

insulative material such as silicon nitride or nonconductive silicon carbide, before or after

the wafer has been traversed with electrical leads as described earlier. The MR stripe 250

in this embodiment is made of a Permalloy (approximately Ni _XFe ₂) layer formed to a

thickness of about 200 A and having an easy axis of magnetization along the directions of

double headed arrow 258, the permalloy layer then being covered with a patterned

photoresist and ion beam etched to define a generally rectangular shape extending about 5

μm longitudinally and about 30 μm laterally, although the exact dimensions of the stripe

may vary from these figures by 50 %, depending upon tradeoffs involved in maximizing

efficiency and stability. The IBE that defines the outline of the MR stripe 250 may

simply remove a window frame shaped border around the stripe, leaving the remainder of

Permalloy layer as a seed layer for the yokes and conductive leads that will be formed

later, that remainder being masked during formation of the MR sensor. Next, a

conductive pattern is formed which provides a pair of conductive leads 260 and 262 to

the MR stripe 222, the leads having respective slanted edges 265 and 268 which are

parallel with each other and with edges of a parallelogram shaped conductive bar 270

formed therebetween. A bias layer of a permanent magnet or an anti ferromagnetic

material such as FeMn optionally underlies the conductive pattern adjoining the MR

stripe 250. in order to pin the magnetization of that stripe in the direction of arrow 272.

The leads 260 and 262 and conductive bar 270 are so much more electrically conductive than the MR stripe 250 that an electrical current between leads 260 and 262 in sections

277 of the MR stripe not adjoining leads 260 and 262 or bar 270 flows along the shortest

path between the slanted edges 265 and 268 and bars as shown by arrows 280, essentially

perpendicular to those edges and the parallel sides of the intervening bar 270 and at a

slant to the easy axis direction 272.

The magnetoresistance of the MR stripe 250 varies depending upon an angle θ

between the magnetic field and the current in the stripe such that the resistance is

proportional to cos 0. In the absence of a magnetic field from the yoke sections 253 and

255, the angle between the easy axis 272, along which the magnetization of the stripe 250

is directed, and the current in magnetoresistive sections 277 as shown by arrows 280, is

between 0° and 90° and preferably near 45°. Upon receiving a magnetic signal from a

disk by a pair of poletips coupled to the yoke sections 253 and 255, so that a magnetic

flux in those sections is directed as shown by arrows 282. the magnetic moment of the

stripe 250 is rotated in a direction more parallel with current arrows 280 so that the

magnetoresistance in sections 277 approaches zero. On the other hand, when a magnetic

pattern on the disk creates a magnetic flux in the yoke sections 253 and 255 in an

opposite direction to arrows 280, the magnetic moment within MR stripe 250 is rotated to

become more nearly perpendicular to current 280 within resistive sections 277, so that

magnetoresistance in those sections 277 rises. This differential resistance based upon the

direction of magnetic flux in yoke sections 253 and 255 creates a voltage difference

which is used to read the information from the disk. Initial steps in the construction of the MR sensing transducer are shown in FIG.

18, in which a wafer substrate 300 of alumina, nonconductive silicon carbide or silicon

nitride has been traversed with thousands of leads as described above, and then polished

and cleaned to provide a planar surface. For the case in which the substrate is coated

rather than pierced with leads, construction may begin with the formation of an MR layer,

described below, on a clean, virgin substrate 300. For the situation in which an alumina

wafer is employed, a few microns of alumina 302 should be deposited and polished to

present a favorable surface for MR formation. A much thicker alumina layer, not shown,

may optionally be deposited, lapped and cleaned atop a nitride etch stop layer and then

covered with a photoresist mask over areas where the ends of the first yoke are to be

raised, so that generally isotropic etching leaves plateaus in those areas similar to plateaus

1 12 of FIG. 6, with the remainder of the alumina layer being removed to expose the etch

stop atop wafer 300. In the preferred embodiment shown in FIG. 1 , first yoke elements

253 and 255 are not raised at their ends and the second yoke curves downward at its ends

to meet the first yoke, in which case the alumina layer plateaus are not needed. For either

case, an MR layer 250 of Permalloy is formed in the presence of a magnetic field by

sputtering or ion beam deposition to a carefully controlled thickness of about 200 A, the

field creating an easy axis of the Permalloy film into or out of the plane of the paper of

FIG. 18. A photoresist is then distributed atop that film and patterned to protect MR

stripe 250 while the remainder of the Permalloy is removed by IBE. Alternatively, the

Permalloy layer may be retained as a seed layer for electroplating yoke layers 253 and

255, read circuit conductive leads 260 and 262, and write circuit conductive leads 31 and 318. In this case, the Permalloy underlying the yoke layers 253 and 255 is separated

by IBE from the MR stripe before the yoke layers are formed.

The Permalloy layer including MR stripe 250 is first covered with a photoresist

which is patterned to expose and IBE a window frame border 308 around stripe 250,

leaving Permalloy layers 313 for later electroplating of the yoke. Another photoresist is

then patterned to cover slanted portions of the stripe corresponding to parallelogram-

shaped sections 277 of FIG. 17 while exposing areas 265, 268 and 270. A bias layer 305

of antiferromagnetic material such as FeMn is then deposited, which pins the easy axis of

the MR stripe in a single direction, as shown by arrow 272 of FIG. 17. A conductive

material such as copper is then deposited atop the bias layer 305 forming the conductive

pattern shown in FIG. 1 7, including bar 270. The photoresist that had covered areas such

as 277 is then removed, taking with it any bias layer 305 and conductive layer that had

been disposed on top of the photoresist. A protective layer 310 of alumina is deposited

atop the MR element 250 and conductive pattern, including bar 255, to a thickness in a

range between 125 A and 1000 A. A photoresist is then distributed atop layer 310 and

patterned to protect that portion of layer 310 covering MR stripe 222 and conductive bar

255, while the remainder of that layer is removed by wet etch or IBE, beginning at the

edge of layers 313.

Another photoresist layer is then patterned to cover a central portion of the

insulation 310 above bar 270 and MR section 277. For the situation in which the

Permalloy that created the MR stripe 250 is not used as a seed layer for the yokes and

conductors, a NiFe seed layer 313 is then sputtered to a thickness of about 1000 A. whereupon a solvent is applied to remove the resist and to lift off any seed layer 313

disposed on the resist. This photoresist lift-off process avoids the need for etching or

other removal of the thin seed layer that would otherwise exist atop the central portion of

insulation layer 310, and thus avoids damage to that layer and the MR elements below.

Top yoke sections 253 and 255 are then formed by window frame plating with gap left

between those sections disposed above the central portion of MR stripe 250. Yoke

sections 253 and 255 overlap MR stripe 250 so as to minimize the interruption of

magnetic flux between the yoke sections 253 and 255 and the MR stripe 250. A pair of

interconnect leads 303 and 307 is then plated through a photoresist mask, then a layer 322

of alumina is deposited and lapped flat to leave a thickness of a few microns above the

yoke layers 253 and 255. A Ti/Cu or MoNiFe seed layer is then sputtered and masked

with a patterned photoresist through which a coil layer 320 is formed, after which the

resist and exposed seed layer is removed.

Referring additionally now to FIG. 19, a terraced pair of top yoke layers 330 and

333 are then formed, as described previously and depicted in FIG. 8 - FIG. 10. the top

yoke layers 330 and 333 sloping to connect at outside ends to flat yoke layers 253 and 255 and rising at a midpoint to connect to poletips 44. The rest of the construction of this

transducer proceeds similarly to that described previously, although one should note that

only a single coil layer 320 is formed for writing, while reading is accomplished with the

MR sensor. The finished planar transducer including MR element 250 built in thin-film

layers on substrate 300 is asymmetrically covered by trailing central pad 30. which is formed of DLC that may be I μm to 1 μm thick, and extends behind poletips 44 by 5μm

to 20 μm and in front of those poletips by 10 μm to 100 μm.

Claims

1. A device for reading or writing information on a spinning rigid disk, comprising:

a slider composed of a plurality of adjoined solid layers disposed between

disk-facing and non-disk-facing major surfaces, leading and trailing ends and first and

second sides, including a self-supporting layer disposed closer to said non-disk-facing

surface than to said disk-facing surface and holding a plurality of electrical leads, a

plurality of magnetically permeable layers coupled as a loop terminating in a pair of

poletips disposed in said disk-facing surface and separated by a submicron amagnetic

gap, with an at least partially conductive layer coupled to said loop and connected to said

leads, and wherein said disk-facing surface has an air-bearing pad disposed adjacent to

both said sides and separated, near a midpoint between said leading and trailing ends, by

a recessed area, said disk-facing surface also having a trailing pad disposed adjacent said

recessed area, said trailing pad encompassing said poletips.

2. The device of claim I wherein said trailing pad extends from said poletips

substantially further toward said leading end than toward said trailing end.

3. The device of claim I wherein said trailing pad has a disk-facing area

substantially less than that of said air-bearing pad.

4. The device of claim I wherein at least one of said pads has a mostly curved

border.

5. The device of claim I wherein said magnetic loop extends further in a direction

substantially parallel to said disk-facing surface than in a direction substantially

perpendicular to said disk-facing surface.

6. The device of claim I wherein said pads are composed primarily of amorphous,

diamond-like carbon.

7. The device of claim I wherein said slider is substantially planar throughout a

common operating temperature range.

8. The device of claim 1 wherein a most common material of said self-supporting

layer is substantially the same as that of most other layers of said slider.

9. The device of claim 1 wherein a metal layer is disposed between said self-

supporting layer and most other said layers.

10. The device of claim I wherein said air-bearing pad has a mostly disk-facing area

adjacent to said leading end having an elevation between that of said recessed area and a

remainder of said air-bearing pad.

1 1. The device of claim I wherein said at least partially conductive layer includes a

magnetoresistive element.

12. The device of claim I wherein said magnetically permeable loop includes a layer

having both flat and curving regions.

13. The device of claim 1 wherein said magnetically permeable loop includes at least

one layer that resembles a clamshell.

14. The device of claim 1 wherein said recessed area extends to said leading end.

15. The device of claim I wherein said leads traverse said self supporting layer.

16. A device for reading or writing information on a spinning rigid disk, comprising:

a substrate having first and second opposed major surfaces, with a

plurality of conductive leads contacting at least one of said surfaces,

a strata mostly covering said first surface and having leading and trailing

ends and lateral edges,

an electromagnetic transducer disposed in said strata and connected to said

leads, said transducer having a magnetic circuit terminating in a pair of poletips separated

by an amagnetic gap. and

a disk-facing surface formed on said strata distal to said substrate and

having a plurality of pads protruding from a recessed area and terminating in mostly flat faces, said pads including an air-bearing side pad disposed adjacent to each of said lateral

edges and a trailing central pad disposed between said edges, with said poletips being

disposed in said central pad face.

17. The device of claim 16 wherein said side and central pads arc composed primarily

of amorphous, diamond-like carbon.

18. The device of claim 16 wherein a most common material of said strata is

substantially the same as that of said substrate.

1 . The device of claim 16 wherein each of said side pads has a mostly disk-facing

region adjacent to said leading end with a height between that of said side pad faces and

said recess.

20. The device of claim 16 wherein said central pad face has an area at least an order

of magnitude greater than that of said poles, and said poles are disposed adjacent to a

trailing edge of said central pad.

21 . The device of claim 16 wherein said magnetic circuit further comprises a

magnetoresistive element.

22. The device of claim 16 and further comprising a bridge between said side pads

adjacent to said leading end.

23. The device of claim 16 wherein a thermal expansion of said strata is matched to

that of said substrate.

24. The device of claim 16 and further comprising a metal layer disposed between

said substrate and said strata.

25. The device of claim 16 wherein said magnetic circuit extends further in a

direction substantially parallel to said disk-facing surface than in a direction substantially

perpendicular to said disk-facing surface.

26. The device of claim 16 wherein said poles are disposed adjacent to a trailing edge

of said central pad face, and said central pad face has a width adjacent to said poles which

is much less than that traversing a center of said face.

27. The device of claim 16 wherein said leads extend between said substrate surfaces.

28. The device of claim 16 wherein said magnetic circuit has a cross-section

resembling a clam shell.

29. A device for storing or retrieving information, comprising:

a rigid disk having a major surface and an associated media layer,

a suspension including an elongate beam having a plurality longitudinal

conductors and extending between a mounting end and a free end over a region of said

surface, and

a wafer die coupled to said beam adjacent said free end, adjoined by a

plurality of leads connected to said conductors, and overlaid distal to said beam with a

strata formed on said die and including an electromagnetic transducer with magnetic

poletips projecting distal to said die, said strata having a disk-facing surface with a

leading pair of side pads and a trailing central pad which encases said poletips.

30. The device of claim 29 wherein said side pads are separated from and said central

pad is disposed in at least occasional contact with said disk surface during

communication between said transducer and said media layer.

31 . The device of claim 29 wherein said poletips are disposed adjacent to a trailing

edge of said central pad.

32. The device of claim 29 wherein said beam is oriented substantially along a

direction of motion of a local portion of said disk closest to said strata.

33. The device of claim 29 wherein each of said surface and said pads are composed

primarily of carbon.

34. The device of claim 29 wherein said transducer further comprises a

magnetoresistive element.

35. The device of claim 29 wherein said side pads have a leading end with a ramp.

36. The device of claim 29 wherein said side pads have a leading end with a shallow

step.

37. The device of claim 29 wherein said central pad is at least somewhat elliptical in

shape.

38. The device of claim 29 and further comprising a thermal compensation element

adjoining said substrate and constraining said strata from warping at operating

temperatures.

39. The device of claim 29 wherein said transducer includes a magnetically permeable

layer with a terraced shaped.