【発明の詳細な説明】
この発明は、絶縁膜を有する薄膜磁気ヘツド用
基板材料の改良に係り、Al2O3−TiC系、
Al2O3TiO2系等のAl2O3系基板上に被着する絶縁
膜たるAl2O3薄膜を、著しく高い付着強度で被着
した基板材料に関する。
今日、コンピユータ用を始めオーデイオ用、
VTR用等の磁気ヘツドは、記録密度の高密度化
並びに耐摩耗性の改善が強く求められており、こ
のためＩ・Ｃテクノロジーを用いて製造する薄膜
磁気ヘツドが最適と考えられている。この薄膜磁
気ヘツド基板材料には、Al2O3−TiC系、Al2O3
−TiO2系等のAl2O3系材料が、耐摩耗性、精密加
工性にすぐれた非磁性基板材料として多用されて
いる。
かかる薄膜磁気ヘツドの性能は、基板材料上に
種々の導電性あるいは非導電性の薄膜並びにパタ
ーンを被着させるため、基板材料自体と絶縁膜と
の接着強度が重要になつてくる。すなわち、一般
に薄膜磁気ヘツドは、導電性を有する上記基板上
に被着積層するパーマロイ、センダスト等の軟磁
性材料またはCu、Au、Al等のコンダクターとの
電気的絶縁性を確保する必要から、前工程で精密
研摩した該基板表面上に、例えばスパツター等で
Al2O3絶縁被膜が被着され、さらにこのAl2O3絶
縁被膜の上に磁気ヘツドパターンが形成され、そ
の後個々の薄膜磁気ヘツドに加工されている。
ところが、このAl2O3系（例えば、Al2O3−30
〜45％TiCなる組成）基板上に、スパツタリング
で直接Al2O3絶縁膜を形成するため、両者の界面
でスパツタリングした絶縁膜と基板間は、結晶組
織的に整合が十分にになされていないため、個々
に分割加工するときに剥離が生ずる恐れがあり、
また、実用スライダーとして走行させた場合に界
面において剥離を生じる恐れがあつた。
この発明は、性能のすぐれた薄膜磁気ヘツドを
得るための基板を目的とし、Al2O3−TiC系、
Al2O3−TiO2系等のAl2O3系基板上に被着する絶
縁膜たるAl2O3薄膜を、著しく高い付着強度で被
着した基板材料を目的としている。
すなわち、この発明は、Al2O3系基板表面に、
該基板と同一成分系でかつ基板よりAl2O3含有量
の多い成分組成からなるAl2O3系薄膜を被着介在
させて、電気絶縁用のAl2O3薄膜を被着したこと
を特徴とする、絶縁膜を有する薄膜磁気ヘツド用
基板材料である。
この発明は、基板と同一成分系でかつ基板より
Al2O3含有量の多い成分組成からなるAl2O3系薄
膜を中間層として介在させることにより、絶縁膜
のAl2O3と基板のAl2O3との結晶組織的な整合を
十分に、被着強度を著しく向上させることを特徴
としている。
この発明において、Al2O3系基板とは、Al2O3
−TiC系、Al2O3−TiO2系があり、Al2O3−TiC
系基板として、Al2O355〜70％、TiC30〜45％を
基本成分とし、さらに副成分としてTiO21〜10
％、ZrO2、MgO、NiO、Cr2O3の各々0.5〜５％、
Y2O30.05〜２％の少なくとも１種を含有する基
板がある。また、Al2O3−TiO2系基板には、
Al2O340〜80％、TiO220〜60％を基本成分とし、
さらに副成分としてZrO2、MgO、CaO、Y2O3の
各々0.5〜５％の少なくとも１種を含有する基板
がある。
Al2O3系基板と電気絶縁用Al2O3薄膜との間に
中間層として介在させるAl2O3系薄膜は、例え
ば、基板組成が65％Al2O3−35TiC系基板の場合、
Al2O3が65％以上でTiC系が35％以下からなる
Al2O3−TiC系薄膜である必要があり、また、基
板組成が60％Al2O3−40TiO2系基板の場合、
Al2O3が60％以上で、TiO2が40％以下からなる
Al2O3−TiO2系薄膜である。
中間層のAl2O3系薄膜は、その被膜厚みと絶縁
用Al2O3薄膜との総和被膜厚みが1μｍ〜50μｍで
ある必要があり、1μｍ未満では絶縁用Al2O3薄膜
の上に被着する磁性膜との電気的絶縁性が磁く、
また50μｍを越える薄膜磁気ヘツドに個々に分割
加工して切断面を研摩する際、基板と絶縁用
Al2O3薄膜との段差が大きくなりすぎるので好ま
しくない。
また、中間層のAl2O3系薄膜の厚みは、基板と
絶縁用Al2O3薄報との接着効果を高めるために
0.1μｍ以上必要であり、その被膜厚みは上記した
如く、絶縁用薄膜との総和厚みが50μｍ以下とな
るよう、薄膜磁気ヘツドの設計に応じて適宜選定
すればよいが、絶縁用Al2O3薄膜の好ましい厚み
は20μｍ以下である。
また、Al2O3系基板の表面は、機械研摩等の所
定の研摩が施されるが、中間層のAl2O3系薄膜を
介して絶縁用Al2O3薄膜との接着性を高めるに
は、基板の表面粗度は1000Å以下、好ましくは
300Å以下にする必要がある。
この発明において、中間層のAl2O3系薄膜及び
絶縁用Al2O3薄膜の被隊方法としては、スパツタ
リング、蒸着等公知の薄膜被着方法が採用できる
が、信頼性の高さからスパツタリングが好まし
い。
Al2O3−TiC系基板上に中間層として同系の
Al2O3−TiC系薄膜をスパツタリングする場合、
所要組成の焼結型Al2O3−TiC系ターゲツトを使
用してもよいが、Al2O3−TiCのスパツター速度
比が異なるため、使用頻度の増大に伴なつて、使
用中にターゲツト中のAl2O3量が増加する恐れが
あるので、Al2O3とTiCの各々のターゲツトを作
製し、パラレル放電によつて薄膜被着を行なつて
もよい。得られる被膜組成は、各々のターゲツト
の寸法、電極間距離、スパツター速度等より算出
され、組成ずれのない安定した薄膜が得られる。
また、基板上の中間層薄膜が所要の組成となるよ
う、Al2O3ターゲツト上に、TiCペレツトを、
Al2O3、TiCのスパツタ速度に基づいて配列、配
置してもよく、さらに、中間層のAl2O3系薄膜の
精密加工性改善のために、Al2O3ターゲツト上に
TiCペレツトの他MgO、Y2O3、TiO2等の添加物
のペレツトを所要組成比になるよう配置してスパ
ツタリングすることもできる。
以下に、この発明を実施例に基づいて詳述す
る。
スパツター装置に高周波マグネトロンスパツタ
ー装置を使用し、スパツター条件として、寸法
100mmφ×４mm厚み、純度99.9％のAl2O3、
Al2O395％−TiC5％、Al2O390−TiC10％、
Al2O380％−TiC20％の４種のターゲツトを用い、
スパツターAr圧は１×10-3torrで、１×10-7torr
に到達後、投入電力600Wでスパツタリングを行
なつた。
基板にはAl2O363％−TiC37％組成のものを使
用し、表面粗度を200Åに仕上げたのち、逆スパ
ツタリングにて表面層を100Å程度除去し、上記
のスパツター条件で中間層を被着した。この場
合、中間層がなく絶縁用のAl2O3薄膜のみのとき
は10μｍ、Al2O3−TiC系３種のときは1μｍの厚
みに被着し、この中間層を介して絶縁用Al2O3薄
膜を上記のスパツター条件で9μｍ厚みに被着し
た。
同一組成のAl2O3−TiC系基板の上に、４種の
中間層をそれぞれ介して絶縁用Al2O3薄膜を被着
した４種の基板において、絶縁用Al2O3薄膜の付
着力をはがれ点、亀裂点で評価し、間層間の分割
加工時の剥離状況とともに第１表に示す。
なお、第１表において、はがれ点及び亀裂点
は、マイクロビツカース硬度計を用いて、打重を
50ｇから1000ｇまで順次増大させ、各保持時間は
30秒として、Al2O3絶縁膜が剥離したときの荷重
をはがれ点とし、該薄膜に亀裂を生じたときの荷
重を亀裂点として評価した。また、基板より分割
して個々の薄膜磁気ヘツドに加工する際の基板と
絶縁薄膜との剥離は、顕微鏡にて判定した。
第１表より明らかな如く、基板材料と同一成分
系でかつAl2O3含有量を増大した中間層の薄膜を
介在させることにより、Al2O3−TiC系基板上に
被着する絶縁膜たるAl2O3薄膜が、著しく高い付
着強度で被着され、薄膜磁気ヘツド用基板として
工業上用途並びに有用性が大きく拡大し基板材料
が得られたことがわかる。
【表】DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvement of a substrate material for a thin film magnetic head having an insulating film, and includes Al 2 O 3 -TiC-based,
This invention relates to a substrate material in which an Al 2 O 3 thin film, which is an insulating film, is deposited on an Al 2 O 3 based substrate such as an Al 2 O 3 TiO 2 based substrate with extremely high adhesion strength. Today, for computers as well as for audio,
Magnetic heads for VTRs and the like are strongly required to have higher recording density and improved wear resistance, and for this reason, thin film magnetic heads manufactured using I/C technology are considered optimal. This thin film magnetic head substrate material includes Al 2 O 3 -TiC system, Al 2 O 3
- Al 2 O 3 based materials such as TiO 2 based materials are often used as non-magnetic substrate materials with excellent wear resistance and precision machinability. The performance of such thin film magnetic heads depends on the adhesive strength between the substrate material itself and the insulating film, since various conductive or nonconductive thin films and patterns are deposited on the substrate material. That is, in general, thin film magnetic heads are manufactured using a thin film head because it is necessary to ensure electrical insulation from soft magnetic materials such as permalloy and sendust, or conductors such as Cu, Au, and Al, which are laminated on the conductive substrate. For example, with a sputter, etc., the surface of the substrate that has been precisely polished in the process is
An Al 2 O 3 insulating coating is deposited, and a magnetic head pattern is formed on the Al 2 O 3 insulating coating, which is then fabricated into individual thin film magnetic heads. However, this Al 2 O 3 system (for example, Al 2 O 3 −30
Since the Al 2 O 3 insulating film is directly formed on the substrate (with a composition of ~45% TiC) by sputtering, there is insufficient crystal structure matching between the sputtered insulating film and the substrate at the interface between the two. Therefore, there is a risk of peeling when dividing into individual parts.
Furthermore, when running as a practical slider, there was a risk of peeling at the interface. The purpose of this invention is to provide a substrate for obtaining a thin - film magnetic head with excellent performance.
The purpose is to create a substrate material in which an Al 2 O 3 thin film , which is an insulating film, is deposited on an Al 2 O 3 type substrate such as Al 2 O 3 -TiO 2 type with extremely high adhesion strength. In other words, the present invention provides a method for forming an Al 2 O 3 based substrate on the surface of the substrate.
An Al 2 O 3 thin film for electrical insulation was deposited by interposing an Al 2 O 3 thin film that had the same composition as the substrate and had a higher Al 2 O 3 content than the substrate. This is a thin film magnetic head substrate material having an insulating film. This invention is based on the same composition as the substrate and is better than the substrate.
By interposing an Al 2 O 3 thin film with a component composition with a high Al 2 O 3 content as an intermediate layer, the crystal structure of the Al 2 O 3 of the insulating film and the Al 2 O 3 of the substrate is sufficiently matched. It is characterized by significantly improving adhesion strength. In this invention, the Al 2 O 3 based substrate refers to Al 2 O 3
-TiC system, Al 2 O 3 -TiO 2 system, Al 2 O 3 -TiC
As a system substrate, the basic components are Al 2 O 3 55-70% and TiC 30-45%, and TiO 2 1-10% as a subcomponent.
%, ZrO 2 , MgO, NiO, Cr 2 O 3 each 0.5 to 5%,
There is a substrate containing at least one type of Y 2 O 3 from 0.05 to 2%. In addition, the Al 2 O 3 −TiO 2 based substrate has
The basic components are Al 2 O 3 40-80%, TiO 2 20-60%,
Furthermore, there is a substrate containing at least one of ZrO 2 , MgO, CaO, and Y 2 O 3 in an amount of 0.5 to 5% each as a subcomponent. The Al 2 O 3 thin film interposed as an intermediate layer between the Al 2 O 3 based substrate and the electrically insulating Al 2 O 3 thin film is, for example, when the substrate composition is 65% Al 2 O 3 -35TiC based substrate.
Consists of 65% or more of Al 2 O 3 and 35% or less of TiC system
It must be an Al 2 O 3 −TiC thin film, and if the substrate composition is 60% Al 2 O 3 −40TiO 2 substrate,
Consisting of 60% or more Al 2 O 3 and 40% or less TiO 2
It is an Al 2 O 3 −TiO 2 based thin film. The intermediate layer Al 2 O 3 thin film must have a total film thickness of 1 μm to 50 μm, including the thickness of the film and the insulation Al 2 O 3 thin film. The electrical insulation with the magnetic film to which it is applied is magnetic,
In addition, when cutting thin film magnetic heads over 50 μm into individual pieces and polishing the cut surfaces, it is necessary to
This is not preferable because the difference in level from the Al 2 O 3 thin film becomes too large. In addition, the thickness of the Al 2 O 3 thin film in the intermediate layer is determined to improve the adhesion effect between the substrate and the insulation Al 2 O 3 thin film.
The thickness of the coating is 0.1 μm or more, and as mentioned above, the thickness of the coating can be selected as appropriate depending on the design of the thin film magnetic head so that the total thickness with the insulating thin film is 50 μm or less . The preferred thickness of the thin film is 20 μm or less. In addition, the surface of the Al 2 O 3 based substrate is subjected to a specified polishing such as mechanical polishing, and the adhesion with the insulating Al 2 O 3 thin film is improved through the intermediate layer Al 2 O 3 based thin film. In this case, the surface roughness of the substrate should be less than 1000Å, preferably
It must be less than 300Å. In this invention, as a method for depositing the intermediate layer Al 2 O 3 thin film and the insulating Al 2 O 3 thin film, known thin film deposition methods such as sputtering and vapor deposition can be employed, but sputtering is preferred due to its high reliability. is preferred. The same type of material is used as an intermediate layer on the Al 2 O 3 −TiC substrate.
When sputtering Al 2 O 3 −TiC thin film,
A sintered Al 2 O 3 -TiC target with the required composition may be used, but since the sputtering speed ratio of Al 2 O 3 -TiC is different, as the frequency of use increases, Since there is a risk that the amount of Al 2 O 3 may increase, separate targets of Al 2 O 3 and TiC may be prepared and thin film deposition may be performed by parallel discharge. The composition of the resulting film is calculated from the dimensions of each target, the distance between the electrodes, the sputtering speed, etc., and a stable thin film with no deviation in composition can be obtained.
In addition, TiC pellets were placed on the Al 2 O 3 target so that the intermediate layer thin film on the substrate had the desired composition.
Al 2 O 3 and TiC may be arranged and arranged based on the sputtering speed, and furthermore, in order to improve precision machinability of the intermediate layer Al 2 O 3 thin film, sputtering may be performed on the Al 2 O 3 target.
In addition to TiC pellets, pellets of additives such as MgO, Y 2 O 3 , TiO 2 and the like can also be arranged and sputtered in a desired composition ratio. The present invention will be explained in detail below based on examples. A high frequency magnetron sputtering device is used as the sputtering device, and the sputtering conditions are as follows:
100mmφ×4mm thickness, 99.9% purity Al 2 O 3 ,
Al 2 O 3 95% - TiC 5%, Al 2 O 3 90 - TiC 10%,
Using four types of targets: 80% Al 2 O 3 - 20% TiC,
Sputter Ar pressure is 1×10 -3 torr, 1×10 -7 torr
After reaching , sputtering was performed with input power of 600W. A substrate with a composition of 63% Al 2 O 3 - 37% TiC was used, and after finishing the surface roughness to 200 Å, the surface layer was removed by reverse sputtering to about 100 Å, and the intermediate layer was covered using the above sputtering conditions. I arrived. In this case, when there is no intermediate layer and only the insulating Al 2 O 3 thin film is deposited, the thickness is 10 μm, and when the three types of Al 2 O 3 -TiC are deposited, the thickness is 1 μm, and the insulating Al is deposited through this intermediate layer. A 2 O 3 thin film was deposited to a thickness of 9 μm under the above sputtering conditions. In four types of substrates, insulating Al 2 O 3 thin films were deposited on Al 2 O 3 -TiC-based substrates with the same composition through four types of intermediate layers. The adhesion strength was evaluated using the peeling point and the cracking point, and the results are shown in Table 1 along with the peeling status during the dividing process between the interlayers. In Table 1, peeling points and cracking points are measured using a micro-Vickers hardness tester.
The holding time was increased sequentially from 50g to 1000g.
The load at which the Al 2 O 3 insulating film peeled off for 30 seconds was defined as the peeling point, and the load at which the thin film cracked was evaluated as the cracking point. Further, peeling between the substrate and the insulating thin film when the substrate was divided and processed into individual thin film magnetic heads was determined using a microscope. As is clear from Table 1, the insulating film deposited on the Al 2 O 3 -TiC substrate can be improved by interposing the intermediate layer thin film, which has the same composition as the substrate material and has an increased Al 2 O 3 content. It can be seen that the Al 2 O 3 thin film was deposited with extremely high adhesion strength, and a substrate material was obtained whose industrial application and usefulness as a substrate for a thin film magnetic head were greatly expanded. 【table】