CA1134945A

CA1134945A - Thin film magnetic recording heads

Info

Publication number: CA1134945A
Application number: CA000310370A
Authority: CA
Inventors: Fred S. Lee
Original assignee: Magnex Corp
Current assignee: Magnex Corp
Priority date: 1977-09-02
Filing date: 1978-08-30
Publication date: 1982-11-02
Also published as: NL7809047A; FR2402270A1; GB2003647B; JPS5449109A; GB2003647A; FR2402270B1; DE2838263A1

Abstract

ABSTRACT OF THE DISCLOSURE

A method of manufacture for forming a novel magnetic read/write transducer head of the type utilizing thin film materials. The method of manufacture comprises steps which deposit a thin film magnetic recording head on a selected substrate having dimensions which enable batch manufacture of a thin film magnetic transducer in combination with its supporting slider assembly.
The substrate of selected material in thick wafer form is subjected to a series of thin film deposition, etching and plating operations to form a plurality of thinfilm magnetic heads thereon. Thereafter, the substrate wafer is diced around each thin film magnetic transducer head with subsequent finishing and polishing to re-quisite shape thereby to yield the complete slider and transducer head assembly.A particular form of thin film magnetic transducer head is further novel in thatthe head utilizes shield and pole pieces that are formed as multi-layer thin film pairs of magnetic material as deposited in order and formation to contain the magnetoresistive stripe and operative elements. The multi-layer pole de-positions may be further altered as to number of thin film layers and thickness thereof in order to shape the magnetic fields associated therewith, especially as regards the trailing edge or write pole formation.

Description

~ 1,.3~15

2 -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~
-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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,-,: ,, . .:, ,, ~, . -,. , ~ , , ~ ~ 3 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.

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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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~3A3L~5 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 . ' ' ' ' ' ' . ' :.' .:. ~ ' I ' ' ~.~t3~

~ , 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 ~3~3~ 5 . 9 ~

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 . . . ~

C~

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 .

s - 13 ~

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 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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- 15 -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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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 ::: : :; : : : :

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~

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:-

1. A method of manufacture for unitarily forming a magnetic transducer head and slider comprising the steps of:
disposing a uniformly thick substrate within a selected deposition environment, said thickness being equal to the desired length of the transducer slider;
depositing by serial acts of deposition and etching a magnetic read/write transducer head with associated con-ductors at a predesignated coordinate area on the surface of said substrate;
cutting said coordinate area from said substrate;
and finishing and polishing said cut substrate to form a transducer slider of requisite size and shape with said magnetic read/write transducer head disposed to place the sensing area in operative position for sense interaction with a recording medium.

2. A method of manufacture as set forth in claim 1 which is further characterized to include steps of:
pre-designating a plurality of said coordinate areas on the surface of said substrate;
depositing a magnetic read/write transducer head with associated conductors at each of said plurality of coordinate areas; and cutting, finishing and polishing each of said cut substrate portions from respective coordinate areas to form plural transducer sliders with said magnetic read/write transducer head thereon.

3. A method of manufacture as set forth in claim 1 wherein said step of depositing includes:
forming a shield adjacent said substrate, said shield being formed of alternating magnetic thin film pairs;
forming a magnetoresistive stripe by depositing a magnetic thin film sensor in insulated disposition over said shield;
depositing read conductors in contact with said thin film sensor; and forming a thin film permanent magnet bias layer over said thin film sensor in insulated disposition therefrom.

4. A method of manufacture as set forth in claim 3 which includes further steps of:
depositing a thin film shield pole in insulated dis-position over said bias layer;
depositing a write conductor in insulated disposition over said shield pole; and depositing a trailing edge thin film pole in insulated disposition over said write conductor.

5. A method of manufacture as set forth in claim 4 which is further characterized in that:
each of said shield pole and trailing edge pole are formed by serial deposition of alternating thin film pairs of magnetic and insulative material.

6. A method of manufacture as set forth in claim 5 wherein said trailing edge pole is deposited to include a great-er number of said alternating thin film pairs than does said shield pole.

7. A method of manufacture as set forth in claim 5 wherein said thin films of magnetic material are deposited at greater thickness than said thin films of insulative material in said shield pole and trailing edge pole.

8. A method of manufacture as set forth in claim 7 wherein:
said alternating thin film pairs are deposited to form said trailing edge pole so that they will have progressive-ly less thickness proceeding upward from said write conductor.

9. A method of manufacture as set forth in claim 4 wherein:
each of said shield, shield pole and trailing edge pole are deposited as alternating thin film layers of Nickel-Iron alloy and silicon dioxide; and said thin film permanent magnet layer is a deposition of high remanence magnetic material.

10. A method of manufacture as set forth in claim 4 wherein:
each of said shield, shied pole and trailing edge pole are deposited as alternating thin film layers of Nickel-Iron alloy and Titanium; and said thin film permanent magnet layer is a deposition of high remanence permalloy material.

11. A method for stabilizing thin film magnetic transducers of the slider type having a flying surface as formed by the method of claim 1, comprising the steps of:

coating the flying surface with a thin film of selected passivation material to increase the long term materials stability of the slider.

12. A method for passivating high speed thin film magnetic transducers of the slider type wherein the magnetic thin films are formed on a substrate that is formed to pro-vide the flying surface, as formed by the method of claim 1, comprising the steps of:
coating at least the flying surface portion of said substrate with a thin film of insulative material of hardness greater than said substrate to increase long term stability thereof.

13. A method as set forth in claim 11 or 12 wherein said passivation or insulative material is an oxide of silicon.

14. A method as set forth in claim 11 or 12 wherein said passivation or insulative material is aluminum oxide.

15. A method as set forth in claim 11 or 12 wherein said passivation or insulative material is silicon nitride.

16. A magnetic transducer head and slider assembly comprising:
a substrate having uniformly smooth surface and thickness at least equal to slider length;
shield means consisting of magnetostatically coupled multi-layer thin films deposited insulatively on said sub-strate;
sensor means and substantially coextensive there-with magnetic thin film deposited insulatively on said shield means;
conductor means in electrical contact with said sensor means;

bias means comprising a thin film of permanent magnetic material deposited insulatively on said sensor means and substantially coextensive therewith;
shield pole means consisting of magnetostatically coupled multi-layer thin films deposited insulatively to overlay said bias means and substantially coextensive therewith;
write conductor means deposited insulatively on said pole means and substantially coextensive therewith;
trailing edge pole means consisting of magneto-statically coupled multi-layer thin films deposited insulatively to overlay said write conductor means; and passive means deposited to overlay and encapsulate the composite of the film layers while exposing said con-ductor means; so as to form a highly sensitive thin film head.

17. A magnetic transducer head as set forth in claim 16 which is further characterized in that:
each of said shield means, shield pole means and trailing edge pole means consist of successively deposited thin film pairs of magnetic material and insulative material.

18. A magnetic transducer head as set forth in claim 17 wherein:
each of said thin films of magnetic material has a greater thickness than the thin films of insulative material.

19. A magnetic transducer head as set forth in claim 18 wherein:
said trailing edge pole means multi-layer thin film pairs are progressively thinner proceeding upward from said write conductor means in order to optimally shape the write magnetic field.

20. A magnetic transducer head as set forth in claim 16 wherein:
said magnetic material is Nickel-Iron alloy;
said insulative material is Silicon Dioxide; and said bias means is high remanence permalloy material.

21. A magnetic transducer head as set forth in claim 16 wherein said sensor means comprises:
a thin film of magnetoresistive material connected to provide read indication to said conductor means,

22. A magnetic transducer head as set forth in claim 16 wherein said substrate comprises:
a body of substrate material receiving said shield means on one end and being elongated in the dimension perpendi-cular thereto, said body being further formed to provide an aerodynamically optimal flying surface along said perpendi-cular dimension and adjacent said shield means.

23. A magnetic transducer as set forth in claim 22 wherein said substrate is Silicon.

24. An improved slider and magnetic transducer head combination comprising:
a substrate material formed unitarily as a poly-hedral body having a first surface defining a slider flying surface, said first surface having a length at least equal to the desired length of said slider flying surface, and said substrate material further including at least a second surface disposed perpendicular to said first surface at one extreme of said length to form said slider; and thin film magnetic transducer means formed in situ on said substrate material second surface adjacent said first surface whereby positioning and orientation of said trans-ducer means relative to said first and second surfaces are determined when said transducer means is formed.

25. An improved slider and transducer head as set forth in claim 24 wherein said substrate material is Silicon.

26. A magnetic transducer head and slider assembly according to claim 24 wherein said desired length of said slider flying surface corresponding to the thickness of a wafer of said substrate material from which said body has been separated upon formation of said assembly.