Note: Descriptions are shown in the official language in which they were submitted.
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BACRGROUND OI~UE I~ IITI 111
2 1, Field of the Inventlon
3 The im7entlon rPl~tes generally to m~gne'ciLc transdu
4 cer heads andg more par~icularly9 but no~ by way of limi~a~ion~
5 it rela~es ~o an impr~ved m~od of manufacture and ar~lcle of
6 the thin film magnetic type of read/wri~e transducer head as
7 used in high speed applica~cions for data sensing relati7e to
8 record media such as tapes9 drums9 dlsks and the 1I ke,
9 2~
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The prior art includes n~unerous types of lndt~c~ive
11 and magnetoresisltive recorder heads o:E the type wlh~ch util~e
12 thin film ~echnology in formationO Suclh prior transdul~er lheads
13 utillize various thin film configur~q~ions,, often times d~ctated
14 by the particul~r intended use9 and generally speaking ~he
pr~or tr~nsd~cer head assemblies h~ve utilized unitar~ th1n
16 film elements such as shields9 poles and other effective sur~
17 faees within the he~d assembly~ A U,S. Pa~ent No~ 398~7~36B
18 in the name of L~zzari does disclose a single multl~layer thin
19 film element in an inductive type transducer headv
The prior ?rt also discloses numerous modes for depo~
21 sition f bricatLon of ~hin film magnetic transducer headsg ~ueh
22 processes includlng the well~kn~wn steps of deposition~ etching~
23 platingg etcO However9 in prior fabrieation of the thin film
24 magnetic he~ds, it was neeessary to first fabr~cate the tr~ns~
ducer head and thereafter ~o bond ~he transducer head onto a
26 selected slider of the type used i~ high speed recorder appli-
27 cations. The various processes at$endant form~ti3n of a thln
2~ film magnetoresistive transducer head are thoroughly discussed
2g~n U,S. Pa~en~ NoO 39~089194 1~ the name of Romank~w and this
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1 patent even deals with batch fabricatlon o~ such magnetic
2 heads. In this teaching, there is utilized a magnetically
3 shielding substra~e composed of a ferrite material, and a~ter
4 fabrication of the transducer head it is still necessary to
bond the finally produced head to a slider or other support
6 mechanism that may be used in conjunction therewith.
7 Se~nA~ o~ ~U~ I~V~ITON
8 The present invention con~emplates a me~hod o manu-
g facture for forming a thin film magnetic read/write transducer
head in situ on a supporting slider element. The method con-
11 sists of selecting a substrate o a thickness consonant with
12 the length of transducer sliderJ and thereafter forming in
13 designated areas on top of the substrate wafer a plurality of
14 thin film magnetic transducer heads utilizing the well-known
15 thin film depositionJ etching and plating techniques There- -
16 afterJ the substrate wafer is diced and each individual section
17 is finished and polished to yield a complete slider with thin
18 film composite head (i.e~ magnetoresistive read and inductive
19 write) or induct-Lve head, and electrical contacts borne thiereon `.
in operative disposition. One type of thin ilm magnetoresis-
21 tive transducer head that is contemplated is of the type that
22 utilizes thin film layers which form a read shieldJ sensor~
23 bias layer, shield pole and trailing edge pole~ and each of the
24 read shield, shield pole and trailing edge pole are made up of
a plur~lity o~ alternating pairs of thin film layers of selec~
26 ted magnetic material. The bias layer is further deposi~ed
27 as a thin film of permanent maignet material immediately adja-
28 cent the read sensor thin film layer of magnetoresistive mater-
29 ial.
`' ' , ' ~ . ` ' . ' . .~ ' ' .` . ' ,' . : , '' ~
34~
1 Therefore, i~ is an object or ~he present invention
2 to provide a magn~ic recording head that provldes high reading
3 ~f~icienc:ies an(l small dimenslons, thus achieving high record-
4. ing cle~lsities,
S It is also an object to provide a thln ~ilm rnagneto-
6 resistive ~ransducer head that includes a shaped write ~ield in
7 order to avoid high reverse field in the trailing edge of the
8 write pole.
9 It is still further an ob~ect to pr~vide such a thin
film tr~nsducer head of the magnetoresistive type th~t includes
11 an oriented magnetoresistive stripe enabling unl~orm and re--
12 peatable device performance,
13 I~ is also an object of the present invention to pro~
14 vide a high resolution re~ding dev;ce having optimum ~lyi~g
surface texture and durability.
16 It is yet another ob~ect of the present invention to
17 pr~vide a thin film magnetoresistive transducer having multi~ :~
18 layer element poles and shields with the trailing edge pole
19 modified in order to yield a significantly improved write char-
acteristict
21 Finally, it is an ~bject o the present invention to
22 provide a method of manufacturing a slider and magnetic trans- -:
23 ducer h~adg in combina~ion by depositing the thin film ~truc-
24 ture on a thick substrate w~ose thickness is approximately
25 equ~l to that of the desired 1ength of ~he recording head :~
26 sl~der so t~at a completely inished lntegrated recording head
27 can be produced wi~h fewer process steps and inalizing with
28 pass~vation coa~ing o~ a~ leas~ the 1ying surfaces of the
29 component~
1 Other objects and advantages of the invention will be
2 evident from the following detailed description when read in
3 conjunction with the accompanying drawings whlch illustrate the
4 in~ention.
5 ~ .
6 Fig. 1 is a perspective view of a substrate wafer
7 with coordinate areas generally designated on a portion o~ the
8 surface, and including the deposited thin ~ilm magnetlc trans-
9 ducer heads thereon;
Fig. 2 is a perspective view of a finished slider and
11 thin film trans~ucer head as constructed ln acco~d~nce with the
12 method of the invention;
13 Fig. 3 is an ~l~ernative ~onstruction o ~lider and
14 plural transducer head assembly as may be constructed in accord-
nce with ~he presen~ me~hod of m~nuacture;
16 Fig. 4 is a perspectiva viewJ greatly enlarged, o~ a
17 finished ~hin film recorder head in dispcsition on i~s associ-
18 ated slider;
19 Fig. 5 is a partia1 section~l view9 greatly enlarged,
of a multi-layer thin film pole or shield of the type utilized
21 in the transducer structure of Fig. 4~
22 F~g. 6 is a partial sectional view, greakly en~arged,
23 of a multi-layer ~hin film trai~ng edg~ pole as utili7ed ln
24 the structure of Fig. 4;
Fig. 7 is a perspec~i~e view iLn exploded form illus-
26 trating further the opersti~e elements of ~che recorder head o~
27 Fig. 4;
28 Fig. 8 1~ ~ ~low diagram of a passivation coating
29 process for tre~.ting thin film magnetic head sliders;
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1 Fig 9 ls a graph illustrating expected lifetimes of
2 one operatlonal parameter o coated slider elements; and
3 Fig. 10 is a graph illustrat~ng expected llfetimes of
4 another operational parameter of the coa~ed slider elements.
5 DE AILED DESCRIPTION_OF THE_NVE TION
6 Referring now ~o Fig~ 1, a wafer of suitable substrate
7 10 is shown with a plurali~y of coordinate areas delineated by
8 dicing lines 12 and transverse dicing lines 14~ In actual
9 practiceJ the wa~er of substrate 10 may be any o several sub-
stances, e.g., a silicon or errite wafer of designated ~hick-
11 ness t whlch is commercially available ln standard diameters
12 ranging from 2 1/4" to about 4" Thus, the coordinate areas
13 laid out ~ver ~he entire surface face 16 of subs~ra~e waer 10
14 would be very great in number since a magnetic transducer pack-
age 18 deposited wi~hin a coordinate area would have dimensions
16 of a few mils sq~are- Thus3 a ~ery great number of magnetic
17 transducer head paekages 189 ei~her induct~ve or composi~e, m~y
18 be simultaneously deposited on w~fer ~urface 16 by means of
19 conventional depositi~n~ masking3 etching and plating tech-
nlques, as will be further described bel~w,
21 After formation of the large plur~lity o magne~ic
22 transducer head packages 18 wi~h~n each coordinate area, the
23 substrate wafer 10 may be c~t along each o dicing lines 12 and
24 dicing lines 14 across the whole expanse o the wafer thereby
25 to produce a large plurality o~ indiv~dual substrate/package
26 combinations which are l~hen finlshed and polished into a trans-
2i ducer-slider combination 20 as shown in Fig. 2. Thus, the
28 substrate w~fer 10 portion having thickness t becomes ~he slider
29 22 portion of the transducer head bearing on one end thereof
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1 the Eormation o~ the magnetic transducing head packflge lB
2 which includes a magne~ic head 24 with pla~ed or deposited con
3 duc~ors~ i~e.g wri~e conduc~ors 26 and read conductors 28, as
4 will be further describedO Finishing of ~he diced wafer sec
tion and comple~ion of ~he slider assembly shaplng includes the
6 provision of a transverse slo~ 30 cu~ ln ~h~ top portion ~f
7 slider 22J beveling of opposed lower corners to form bevel ~ur
8 faces 32 and 343 and ~nal polishi.ng of the flying surfaces 36
9 across the underside~ Thus, there ls formed a complete ~lider~
transducer head assembly 20 in rela~ively ewer proc ss s~eps
11 that is ready or opera~cional usage~
12 Fig ~ 3 ~ llustraDces a finished ~riple head slider 40
13 that is manufactured in a similar type of process9 it only
1~ being necessary ~o c~ange ~he coordina~e layout o~ subs~ra~e
15 waer sur:~ace 16 for coael~ion with ~he parl~icular scheme of
16 deposltion pat~erns, e~ching masks, and other incidental pa~
17 terning wh~ch may be attendant~ The triple head sl~der 40 is
lB formed with length t equal to the depth of substrate wafer 10
19 and is then ~inally finished and polished to include a trans-
verse slot 42 and a plurality of bevel edges 44 that define : :
21 underside flyirlg suriEaces 46J 48 and 50 coplanar with the
22 sensing sltripes of th~n ilm transducer head packages 52, 54
2~3 and 569 respec'c~velyO The plating or deposiLtion process also
24 provides the requlsi~e read and wri~e conductor leads for each
of heads 52, 54 and 56 as exposed for contact: on ~e waer
2:6 surface portion or end 58 of sllder 40, Such multi ~rack
27 slider recording head assem~lies m~y be formed for any mul~iple
28 of thln film recordlng headsg and these may be batch formed by
29 utilizing ~e requisite deposition and maslclrlg procedures~
3~Si
1 Fig. 4 illustrates in greatly enlarged ~orm magneto-
2 resistive read/write transducer head 60 as it is partlcularly
3 constructed in accordance with the present invention~ The
4 depiction of Fig~ 4 shows ~he su~s~rate 62 ~the slider portion~
in finished form as it would be s~ped and polished for flnal
6 operational usageO At the pre~ent time, the substrate 62 is
7 selected to be of silicon since it: has deslrable high heat con-
8 duc~ivity and surface smoot~ness t:ha~ aids in rece~ving thin
9 film depositions thereon. The silicon material also lends
itself to mllling and m~chlning or formatlon of the inal
11 slider assembly.
12 During format~on of magnetoresisti~e head 60, the
13 substrate 62 i~ flrst o~Terlaid with a firs~c deposi~lon surface
14 64 of insulator material that is non magnetic ln char~cter and
of hard dielectric quality, Such insuLated material may be
16 such as Al2039 Si3~4 or other oxides of slllcong all ma~er~als
17 having requlsite proper~les ~ha~ are easily deposi~e~ and
18 conducive to various et~.hing tec~niques. Or~ in the case of
19 silicon substrate9 the init~al surface can be heat treated in
an oxidizing atmosphere to form a layer of æ~ on dioxide, a
21 well known art in the semi~co~ductor industry. Next is depo- :
22 sited a read shield 66, ~ multi~layer magnetic structure that
23 is made up of an e~en n~mber of pairs of ~ickel~Iron thin film
24 with a thin SiO2 or Ti~anlum f~lm layer in al~e~na~ion, Thus3
the even num~ered pairs of thin films form magnetostatically
26 coupled pairs, and serve to lower ~he ~o~al magne~ic energy
27 required as well as ta remain in stable domain positlon along
28 a preferred direc~ion~
29 Figure 5 illustrates a portion of thin film shield 66
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1 in enlarged ~orm, ~hus, a irst deposi~ion may be such as
2 silicon dioxide (SiO2) to a thickness of from 20 to 1000 Ang-
3 stroms9 and the pairs would then consist of successive overlays
4 of thin film of Nickel-Iron (NiFe) 709 each tc a thickness of
from 500 to 2JOOO Angs~croms. The thickness of ~he SiO2 thirl
6 film 68 and NiFe thin filmg 70 may be varled within eonsider-
7 able limi~s thereby to alter ~he n~gnet~c properties and re-
8 sponse character~tics i~ desired ma~ner, Accordinglyg shield
9 66 is ~hen finally formed by the s~ack~ng of a plurality of
such pairs of thin films 70 as success~vely ~pplied by deposi-
11 tion and as separated by intersticed formations 68. In device
12 fabricationg the multi-layer thin films 68 70 may be deposited
13 successively by any o several well-~nown ~echniques, including
14 vacuum evapor tion o sputtering techn~ques9 and the operation
15 can be performed in a single vacuum pump down. The p~tern
16 limits o thin fi~m may then be etched eitlher by chemical
17 etching9 ~putter eltchingg or by ~e ion~milling methodO
18 A rel~t~Tely thin film of insulator 72 (see F~g. 4~
19 is then deposited over the slhield 66~ and ~he lnsulator once -:
20 aga~n may be A1203 or the well-knowtl gla~ compositiorl~ includ~
21 ~ng SiO2 and related silicates and sllicon n~ltride. A magneto-
22 resistive (MR9 ~ensor 74 i~ then deposLted to c~erlay the sh~eld
23 66 in insulati;vely spaced dlsposll~ion. Sensor 74 con~ists o
24 a deposition of magnetoreslstlve material~ such as NiFe alloy,
25 and suitable conduct~ve contact layer ~ s formed in extension,
26 as alt 76 and 789 to recei~e elec~ri ally con~uctive contac~
27 with plated conclucltors 80 and 820 Reerring also to Fig, 79
28 conductor films 80 and 82 may be form~d by corn1en~ional conduc~
29 tor depositiGn of such a~ gold, aluminum or the likR as applied
.. . . . . . . .. . . . ..
3L~L3~e3~5
using flashing atld pl~lting proresses thr~lgh ~he requisi~e
2 masklngO ~e thln fllm MR sensor 74 m~Ly be deposited or
3 spu~ered ~o a thickness rangffig from 200 through 500 Angstroms,
4 depend~g upon tlhe deslred characteri~tlcs to be imparted to
the magnetic read head,
6 The next ~hin fllm o illsulator malterial, e,g~, 'che
7 similar gla8S or glass~llke materlals as previously specified,
8 is deposited across cond~etors 8() and 82 and the MR sensor 74.
9 This surfa~e then receives depos~t:Lon O:e a bi~s thin fllm 86
which consists of a ~in ilm deposit of suitable permanen~
11 ma8net material such as Alnico or o~her hlgh remanence alloy.
12 The permanent magnet bias ~n film 86 provides control of thin
13 film domain oriQnta~fo~ wltlhin the read elements. Another
1~ deposiltion of insulator 88 lklhen overlays bla~ tlhin film 86 to
recei~e depos~tion in properly spaeed manner vf a shield pole
16 90 which may be idenltical to l~e pole 66 as shown in ealarged
17 :eorm ln FigD 5O ~IUS9 ~hield pol2 90 consists of suceess~e
18 layers of magraet~ tatie~l~ y oup~Pd pa~rs o~ SiO~ or Ti and
19 NiFe t~in i~ilms lto a requls~te staclking height9 for example,
on the order of 209000 AngstrcDms, ~e sh~.eld pole 90 i~ also
21 ~en o~arlaid with ~n insulator film 92 of t:he same type pre~
2? viously used9 to rece~v~ depos~tion ~ a write conductor 94 ~s
23 d~ sposed for ~ndu~t~e e~upling to its associate write poles .
24 T~le write condue¢or 94 may be formed in requis~e pa cern by
sputtering wi~ sulb~equenlt plating o~ conducti~e m~terial to
26 de~ired thie~essO ~ -
27 A ~in~l ~sulat~e thirl film 96 is th2n applied to
28 receive tlhereon a trailing edge pole 98 of tlhe mullti-layer thin
29 film typeO ~usg tra~ling edge pole 98 al~o consis~ of a
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1 st~ck of magnetostati¢ally eoupled pairs o~ NiFe thin films
2 102-102n, however9 the thickness and arrangement i5 altered in
3 order ~o shape the wri~e field of the uni~ us~ as shown in
4 Fig, 6~ the pa~ring of the N~Fe thin fllms 102 are utilized to
form ~he s~acked palrs o magnetos~a~ically coupled thin film~;
6 however9 the write pole element is desirably shaped by progres-
7 sively redu¢ing ~ehe ~ ckness of successl:ve ~chln films 102 pro-
8 ceed7ng t~ward the trail~ng edge of the record head 600 This
9 i5 illustrated in Figo 6 a$ it ean be seen that the upper two
10 thin films to ilm 102n ar~ each of propor~ional diminu'cion
11 relative to the base thin f ilm 102 0
12 Referring again tel~ Figo 49 each of shield 669 shield
13 pole 90 and trailing edge poLe ~8 are o:~ generally square pla-
14 n~r expanse witlta~ t:lhe record ~aead 60, T~lus9 the tral~sverse
dimension i~lustrated by arrow 104 n~y be of the order o~ 005
16 to 104 m~l as defiraed by t~ record~ng track density require~
17 ments9 and the dim~ sion perpe~dicular thereto9 or the depth
18 of ~he re~pect~7e $hield~ and poles9 may be patterned to be
19 ~pproximately the same or l~rger ex~ee~ading the film stack in
20 directio~ ~ 30O ~e f~nal stac~ad th~n f~llm stNcture is then
21 encapsul~ed by suitable pass~tion material sueh a~ glass or
22 other ~rmet~cally sealing ma~erial as applied in a coa~ing 106
23 and9 i~ desired9 a ~h~n eoat~ng of sueh pass~a~ion materiàl
24 106 m~y be e~tended ~ver ~he entire magnetie head face to be
final~y fin~shed ~n conju~ction with the fly~ng ~urface of ~ub~
26 stra~e 620
27 The read and wr~te conductors are shown generally as
28 being puttered and plated cn the s~des o~ recording head 60~ :
29 In Figo 49 the write con~uctors 110 and 112 and read conductors
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1 114 and 116 may be formed by any oE several acceptable integra-
2 ted circuit techniques to provide the proper conductor co~tin~
3 uity, shown generally for wrlte conductor ~4 by dash lines 118
4 and 12OJ and for read conduc~or 8() and 82 by means ~f dash
lines 122 and 124. Such connectic)ns may be made or example
6 by prQvision of deposition and plating with proper masking and
7 etching during the actual thin ~ilm deposition process with
8 subsequent bonding or plating of external lead connecto~s, as
9 is well known in the art, Such techniques are fully described
in the aforementioned U.S, Patent No. 3,908,194 ~o name but a
ll single source.
12 Fig, 7 better illustr~tes ~he manner of forma~ion o~
13 the read and write conductors as ~hey are deposi~ed, etched and
14 plated during the thin ~ilm formation process. Thus, after
deposition of the MR fllm 74, with pr~vision of e~tensions 76
16 and 78, the metal conductors 80 and 82 are formed, ad~acent
17 thereto and in electrlcal contact, t~ extend outward and rear-
18 ward in hairpi~ con~iguration (116 and 114) where subsequent
19 contact procedures will enable e~ternal terminal connections~
In like m~nner3 after formation o insulati~e film 92 ~Fig. 4)
21 in overlay on sh~eld pole 90, the inducti~e write cond~or 94
22 is similarly deposited and plated to extend lateral rea~ward
~3 c~nduc'cor portions 112 and 110 for ormation of external write
24 terminals. The numerous insulative films are om~tted from Fig.
25 7 for clarity~ but they would of course be present in ~al
26 formation and tlle p~ss~vation coating 106 is ~hen applied ~er
27 the entire thin film formation with exposure of only the ~er-
28 minal contacts :Eor read conductor plates 116 and 114, and wr~te
29 conductor plate~ 112 and llOo
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When in operation, the slider ~ransducer head assemr
2 bly is positioned or sen~ing with the recording medium moving
3 in the direction of the arrow 132 in Fig. 4, I.e., perpendicu-
4 lar to the shield 66, shield pole 90 and trailing edge pole 98~
5 In the read mode, the sensor 74 pr~vides rnagne~oresistive pick-
6 Up a9 energy change information is conveyed by dlrect connection
7 ~o ~che read conductors 80 ~nd 82, Domain orien~a~on of the
8 magnetoreslstive sensor 74 is assured by the permanent magnet
g bias thin film 86 overlaid thereon in insulative dispo~ition.
The polar elemen~s in read mode are the shleld 66 and shield
ll pole 90 which ~unetions as a shield during read opera~ionJ thus
12 defining the magnetoresistive ~tripe at the read sensing inter-
13 face. In write mode9 shield pole 90 then functions as a lead-
14 ing edge pole in conjunction with the trailing edge pole 98,
and induotive coupling to ~he wr~te conduc~or 94 provides ou~-
16 put of write lndication via w~ite conductor~ 110 and 112.
17 It has been found that the ruggedness andJ therefore,
18 the length of useful life of the thin film slider elements can
19 be greatly lengt~ened by ~ub~ecting the entire elemen~ ~o a
2~ passivation process that shields the element from air and pro-
21 vides a hard protecti;~re coating. Not only does ~he passivation
22 coating impro~e the long term material~ stability of the slider,
23 but it contributes to protec~ion of the slider flying suraee,
24 i~e., the surface, ~ncluding flyer bevels, whie~ rides ad~acent
the par~lcular recording medium during high speed reeordlng
a5 operatio~. Accordingly, a teehnlque has been developed for
27 coatin~ of the finished slider ass mbly thin film transducers
28 thereby effeetively to pas~ivate the NiFe ~nagnçtic film struc-
29 tures with coating materials such as the usually employed
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1 passi~a~ion materlal~, e.g., SiO2, ~1203, Si3N4, etc., thls
2 increasing the lifetime of the MR ~ensors ~o ~ calculated equi-
3 valent li~etime on ~he order of 1J 00~ years- Such ~igure is
4 derived from data assembled rela~ive ~o studies compiled or
bubble-type MR sensors under similar operating conditions, ae
6 will be further described below.
7 An a~tendant benefit als,D derives ~rom passivation
8 coating with SiO~ or Si3N~ in that the fly~ng ~urfacc of the
9 slider asscmbly is greatly s~reng~hened by ~he hardne~s of the
coati~g material. The coating technique will have the quality
11 of improving the compatibili~y of the slider assemblies with
12 future media which in all probability ha~e harder surface char-
13 acteristics. Thus, it is e~tremely desirable that slider assem-
14 blies formed ~rom silicon wafers in accordance with the present
di~closure include the ru~gedi~ing passivation coating, Thiæ
16 is due to the start-stop requirements of ~he h~ads, especially
17 those of the l~ght loading type such as the IBM 3340 (Winches~
1~ ter-type~ In addition, the passivatlon technique wlll apply
19 equally for benefit of other forms of thin f~lm structure such
as thin film transducers for rnagnetic tape recording and read-
21 out.
22 The pre~ent pas~ivation or coa~ing ~ec~nique is par-
23 ticularly suitable for thin film transducer slider assemblies~
24 e.g., as shown in Fig~. 2 and 3, which are batch-fabricated
using silicon in wafer orm as the substrate. The use of a
26 silicon block 8S slider of~rs the advantage o~ providing a
27 large heat sink to the transducer thereby providing a oonstant
28 room temperature operation for the vital read/write elements;
29 however, sin~e silicon is a relatively soft materlal for such
.,
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use ~ slider material ln stop/~art, high speed recording
2 application~, its unctional usage is greatly enhanced by the
3 present coa~ing technique as i~ serves to provide a relatively
4 hard surfa~e coating on the slider contact's surface, e.g.,
surfaces 46, 48 and 50 of Fig. 3,
6 As shown in Fig~ 8, the ~tep of slider fabrication
7 140 would take place in ~he manner described previously rela-
8 tive to Figs, 1-7 to ba~ch-fabricate ~he single or p:Lural head
4 sLider assemblies, After individual sl~der a~rica~ion ~nd
10 requisite trimming and polishing, the sliders are gubjeeted to
11 a final cQating step or process 142 wherein the requisite
12 passivation material is deposi~ed entirely over all exter~or
1~ surfaces of the slider assembly, or a~ least on the 1ying sur-
14 faces and adjacent edges, Once aga~n, coating of the pass~va-
t~on material may be carried out by the convent~onal vacuum
16 evapora~ion or eputtering techniques to a sufficlent thickness.
17 There is no definitive 1 imit as to thickness of coating, o~ly
18 that which is neces~ary to passivate or seal the slider as~em~
19 bly; thus, the thicknes~ of coating anay vary from 1,000 Ang-
20 stroms ~o as much as 5,000 Angstroms, seleetion being dictated
21 by the exigency of the particular applica~ions and intended
22 usage.
23 Af~er final coating s~ep 14~, a fin~shed slider :~
24 assem~ly 144 would be ready for operational usage in high
~peed recording applications, silicon bas~ ~tructure 146 there-
:26 of being en irely protçcted by the passi~ation coating. In
27 additionJ the flying sur~ces 148, 150 and 152 as well as t~e
2~ ad~acent surfaces of the triple head slider element would be
29 entirely passivated by he coating procedure. As is desirable
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fl~S
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1 prac~ice for some applica~ions, be~el surfaces 154, 156 and
2 158 are provided to enhance flylng capabillty of the slider
3 ele~ent 144 adjacent a storage surface durlng high ~peed opera-
4 tion.
It is preferred that the sputtered or evaporated
6 passivation coating be ~f material selected rom such as S102,
7 A1~03, Si3N~ and other related passi~ators) and ~he graphs of
8 Figs. 9 and 10 illustrate the e~fects of th~ co~ting technique
9 in terms of critical slider paramelters~ '~he data was complled
1~ to illustrate passivation effects on bubble;-type MR sensors and
11 was published by C. H. Bajo~ek and A. F. M~yadas, AIP Conerence
12 Procedure~, 1972. The testing was carried out in an annealing
13 temperature of ~50C. on MR film of 200 Angstrom.
14 Flg. 9 plots coerc~ve force H~ versus time L~ hundreds
of hou$s with the first 100 hours having the spe~imen maintained
16 in vacuum. Thus~ it can be seen that the coercive force of
17 material~ rem~ined steady in vacuum but sh~wed wide di~ergence
18 when displaced into an a~r en~ironment after 100 hours. Curve
19 160 rep~e~ents an uncoated film and its plot shows a ~apid di-
vergence to a high coerci~e force in air. Curve 162 sh~ws somR-
21 what less but still an inereasing coercive force over the period
22 of testingJ and in this case the film was coated with Schott
~3 glass. Curve 164 represents film coated wi~h SiO2 ~hat s~ill
24 exhibits cansiderable and increasing d~ver~ence to high coer-
2~ cive forces. Finally~ curve 166 represents film coated wi~h
26 Si3N4 or SiO~ and curve 168 shows the efect of coating with
27 Al~0$. The coating w~th any of 5i3N~J SiO or A1203 exhibits
28 a good maintenance o~ low coerci~e force as tested in an air
29 environment over the full period of test time.
.; :
17 ~ ~ 3 ~ ~ 5
1 l~e graph o Fig. 10 is a graph depicting deteriora-
2 tion or M/M~, a ratio of instan~a~eous magnetization versus
3 beginning magnetization at ~ime zero. Once agaln, the flrst
100 hours were maintained in ~acwlm and it can be seen that all
5 coating materials as well as the umcoated material ~emaln a~ a
6 constant value in vacuum. During the latter 400 hours of test-
7 ing with specime~s in air, ~ilm coating plots are as ~ollows:
8 line 170 represents A1203~ SiO andl Si3N4; line 172 represents
9 SiO2; curve line 174 represents Schott glass; and, the line 176
represents the performance of the uncoated MR ilm relative to
11 detarioration. Once againJ it is apparent that the A1203, SiO
12 and Si3N4 coating~ exhibit the superior resistance to deterior-
13 atiQn and are thereore most desirable for use as the passi~a-
14 tion coatlng relatl~e to the present process.
The foregoing discloses both a method o manufacture
16 and an impraved light-loading magnetic recording head of the
17 thin film ma~netoresistive type as well as a process for passi-
18 vation of such heads~ The present invention utilizes an
19 entirely di~feren~ form of transducer element formation by
multi-layer thin film depositicn, and such manipulation of the
21 degree and ~ype of homogeneity of transducer element greatly
22 enhances the versatility and applications or thin film magne-
23 tic transducers of either the induct~ve or magnetoresisti~e
24 type. Further~ the subsequent passivati on process impro~es
long term materials stability and high speed flying capabili-
26 ties. While the foregoing descrip~ion makes re~erence to cer
27 tain dimensions and materials9 it should be understood that
28 there are numerous materials suitable :Eor construction of thln
29 film magnetic heads as described, and the particular thin film
,
~i ::: : :; : : : :
L5
1 dimensions may also be sub3ect to wide variation depending upon
2 operational attributes of a particular magnetic transducer.
3 Changes may be made in l:he combination and arrange-
4 ment of elements as hereto~ore set forth in the specification
and shown in the drawings;. it being understood ~hat changes
6 may be made in the embodime~ts disclosed without departing
7 from the spirit and scope of the invention as defined in the
8 ollowing claims~
