JP2007154285A - Method for producing magnetic film of cobalt-platinum alloy - Google Patents
Method for producing magnetic film of cobalt-platinum alloy Download PDFInfo
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- 229910001260 Pt alloy Inorganic materials 0.000 title claims abstract description 27
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 17
- GUBSQCSIIDQXLB-UHFFFAOYSA-N cobalt platinum Chemical compound [Co].[Pt].[Pt].[Pt] GUBSQCSIIDQXLB-UHFFFAOYSA-N 0.000 title claims abstract 15
- 238000007747 plating Methods 0.000 claims abstract description 32
- 238000004070 electrodeposition Methods 0.000 claims abstract description 30
- GFHNAMRJFCEERV-UHFFFAOYSA-L cobalt chloride hexahydrate Chemical compound O.O.O.O.O.O.[Cl-].[Cl-].[Co+2] GFHNAMRJFCEERV-UHFFFAOYSA-L 0.000 claims abstract description 8
- 239000002253 acid Substances 0.000 claims abstract description 7
- NGPGDYLVALNKEG-UHFFFAOYSA-N azanium;azane;2,3,4-trihydroxy-4-oxobutanoate Chemical compound [NH4+].[NH4+].[O-]C(=O)C(O)C(O)C([O-])=O NGPGDYLVALNKEG-UHFFFAOYSA-N 0.000 claims abstract description 6
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 148
- 229910052697 platinum Inorganic materials 0.000 claims description 87
- 238000010438 heat treatment Methods 0.000 claims description 70
- 229910017052 cobalt Inorganic materials 0.000 claims description 13
- 239000010941 cobalt Substances 0.000 claims description 13
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 13
- 239000007788 liquid Substances 0.000 claims description 3
- 238000000034 method Methods 0.000 abstract description 11
- 229910045601 alloy Inorganic materials 0.000 description 91
- 239000000956 alloy Substances 0.000 description 91
- AVMBSRQXOWNFTR-UHFFFAOYSA-N cobalt platinum Chemical compound [Pt][Co][Pt] AVMBSRQXOWNFTR-UHFFFAOYSA-N 0.000 description 85
- 239000000203 mixture Substances 0.000 description 60
- 239000006104 solid solution Substances 0.000 description 30
- 239000000243 solution Substances 0.000 description 19
- 239000013078 crystal Substances 0.000 description 15
- 238000012545 processing Methods 0.000 description 13
- 239000000758 substrate Substances 0.000 description 11
- 229910018979 CoPt Inorganic materials 0.000 description 9
- 239000000463 material Substances 0.000 description 9
- 238000012916 structural analysis Methods 0.000 description 8
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 7
- 239000011651 chromium Substances 0.000 description 7
- 239000010949 copper Substances 0.000 description 7
- 229910052710 silicon Inorganic materials 0.000 description 7
- 239000010703 silicon Substances 0.000 description 7
- 238000005259 measurement Methods 0.000 description 6
- 229910052751 metal Inorganic materials 0.000 description 6
- 239000002184 metal Substances 0.000 description 6
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 5
- 238000004833 X-ray photoelectron spectroscopy Methods 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
- 238000004458 analytical method Methods 0.000 description 4
- 239000011889 copper foil Substances 0.000 description 4
- 238000010894 electron beam technology Methods 0.000 description 4
- 238000002524 electron diffraction data Methods 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 230000005540 biological transmission Effects 0.000 description 3
- RKTYLMNFRDHKIL-UHFFFAOYSA-N copper;5,10,15,20-tetraphenylporphyrin-22,24-diide Chemical group [Cu+2].C1=CC(C(=C2C=CC([N-]2)=C(C=2C=CC=CC=2)C=2C=CC(N=2)=C(C=2C=CC=CC=2)C2=CC=C3[N-]2)C=2C=CC=CC=2)=NC1=C3C1=CC=CC=C1 RKTYLMNFRDHKIL-UHFFFAOYSA-N 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 238000005530 etching Methods 0.000 description 3
- 229910000765 intermetallic Inorganic materials 0.000 description 3
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- 239000002244 precipitate Substances 0.000 description 3
- 238000001556 precipitation Methods 0.000 description 3
- 238000001228 spectrum Methods 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 2
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- 235000011114 ammonium hydroxide Nutrition 0.000 description 2
- 238000013459 approach Methods 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
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- 238000011437 continuous method Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000009713 electroplating Methods 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 230000005415 magnetization Effects 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 238000005185 salting out Methods 0.000 description 2
- 238000004544 sputter deposition Methods 0.000 description 2
- 238000000992 sputter etching Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 229910000684 Cobalt-chrome Inorganic materials 0.000 description 1
- 229910003771 Gold(I) chloride Inorganic materials 0.000 description 1
- ZSBXGIUJOOQZMP-JLNYLFASSA-N Matrine Chemical compound C1CC[C@H]2CN3C(=O)CCC[C@@H]3[C@@H]3[C@H]2N1CCC3 ZSBXGIUJOOQZMP-JLNYLFASSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- WAIPAZQMEIHHTJ-UHFFFAOYSA-N [Cr].[Co] Chemical compound [Cr].[Co] WAIPAZQMEIHHTJ-UHFFFAOYSA-N 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 238000003287 bathing Methods 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000010952 cobalt-chrome Substances 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 239000008139 complexing agent Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 229910003460 diamond Inorganic materials 0.000 description 1
- 239000010432 diamond Substances 0.000 description 1
- LVOXSMIIOWTHNF-UHFFFAOYSA-L dichloroplatinum hexahydrate Chemical compound O.O.O.O.O.O.Cl[Pt]Cl LVOXSMIIOWTHNF-UHFFFAOYSA-L 0.000 description 1
- 238000007598 dipping method Methods 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- FDWREHZXQUYJFJ-UHFFFAOYSA-M gold monochloride Chemical compound [Cl-].[Au+] FDWREHZXQUYJFJ-UHFFFAOYSA-M 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 230000000873 masking effect Effects 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 229910021421 monocrystalline silicon Inorganic materials 0.000 description 1
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- 239000000843 powder Substances 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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Abstract
Description
本発明は、磁気記録媒体を構成する磁性膜の形成に関し、特に、コバルト−白金合金（以下、Ｃｏ−Ｐｔ合金と略す場合もある）磁性膜を電析めっきにより形成する成膜技術に関する。 The present invention relates to the formation of a magnetic film constituting a magnetic recording medium, and more particularly to a film forming technique for forming a cobalt-platinum alloy (hereinafter sometimes abbreviated as Co-Pt alloy) magnetic film by electrodeposition plating.
近年、情報化社会の進展に伴い、多量のデータを高速に記録し保存する必要性から、情報ストレージの中核をなす磁気記録メディア（ハードディスク）では、高密度記録化、小型化が急速に進められている。現在では、製品レベルで５０〜７０Ｇｂ／ｉｎｃｈ２、研究レベルで１５０〜２００Ｇｂ／ｉｎｃｈ２に達している。これに伴って、媒体に記録させるビットサイズも小さくなり、記録ビット長はマイクロメートルから数十ナノメートルまで微細化が進んできている。今後、この面記録密度の高密度化や記録ビット長の微細化は、さらに進行していくことは明らかで、密度としてはＴｂ／ｉｎｃｈ２で、ビット長は４０ｎｍ×１５ｎｍにまでなると推定される。 In recent years, with the advancement of the information society, magnetic recording media (hard disks), which are the core of information storage, are rapidly becoming denser and smaller in size because of the need to record and store large amounts of data at high speed. ing. At present, at the product level 50~70Gb / inch 2, it has reached the 150~200Gb / inch 2 at the research level. Along with this, the bit size to be recorded on the medium is also reduced, and the recording bit length has been miniaturized from micrometer to several tens of nanometers. In the future, it is clear that the surface recording density and the recording bit length will be further reduced. The density is Tb / inch 2 and the bit length is estimated to be 40 nm × 15 nm. .
従来の情報記録媒体では、記録密度が１０３倍以上の大きな変化をしてきたにも関わらず、この間コバルト−クロム（以下、Ｃｏ−Ｃｒと称す）系磁性膜が一貫して使い続けられてきた。これは、Ｃｏ−Ｃｒ系材料が記録媒体に要求される各種問題に対応して材料特性を改良できるだけの設計自由度の高い材料であったことが主因と考えられる。 In the conventional information recording medium, the recording density despite has been a significant change of more than 10 3 times, during which cobalt - chromium (hereinafter referred to as Co-Cr) based magnetic film has been continued to use consistently . The main reason for this is thought to be that the Co—Cr material was a material with a high degree of design freedom capable of improving the material characteristics in response to various problems required for the recording medium.
現在、記録媒体が直面している課題は、媒体ノイズの低減と記録ビットの熱的安定性確保の両立である。媒体ノイズを低減する為に結晶粒を微細化すると、それに伴って記録ビットの熱安定性が劣化するという関係がある。つまり、粒子を微細化すると磁化の熱揺らぎによってメモリー情報が消失するという問題が生じるのである。このような問題を解決するためには、高い磁気異方性定数を持つ材料を選択すればよいと考えられている。 Currently, the problem facing the recording medium is to reduce both medium noise and ensure the thermal stability of the recording bit. There is a relationship that if the crystal grains are made finer in order to reduce the medium noise, the thermal stability of the recording bit deteriorates accordingly. That is, when the particles are miniaturized, there is a problem that memory information is lost due to thermal fluctuation of magnetization. In order to solve such a problem, it is considered that a material having a high magnetic anisotropy constant may be selected.
現状のＣｏ−Ｃｒ系媒体では、材料特性的に高密度記録化の限界に達しつつあり、１Ｔｂ／ｉｎｃｈ２級の記録密度を実現するためには、新たな記録膜材料の開発が必要となってきている。 The current Co—Cr-based medium is reaching the limit of high density recording in terms of material characteristics, and in order to realize a recording density of 1 Tb / inch 2 class, it is necessary to develop a new recording film material. It is coming.
そのため、本願発明者等は、Ｃｏ−Ｃｒ系媒体の代替材料として、コバルト−白金（Ｃｏ−Ｐｔ）合金磁性膜に着目し、鋭意研究を続けてきた。このＣｏ−Ｐｔ合金磁性膜は原子組成比が１：１である場合、高密度の磁気記録媒体への応用としての可能性があり、近年特に注目されている。それは、Ｃｏ−Ｐｔ合金磁性膜が通常不規則なｆｃｃ構造をとっているものの、６００〜７００℃付近で熱処理を行うと、ＡｕＣｌ型、Ｌ１０のｆｃｔ構造の規則構造となり、高い一軸結晶磁気異方性を有するためである。このこのＣｏ−Ｐｔ合金磁性膜の製造方法として、湿式法のものが知られている（特許文献１参照）。
特許文献１では、いわゆるブロードバンド化による大量情報通信技術の進展を考慮し、高密度記録媒体を大量且つ低コストで提供できる製造技術を提供すべく、大量生産の可能となる電析めっきという湿式法による磁性膜製造技術を開示している。 In Patent Document 1, in consideration of the progress of mass information communication technology due to so-called broadbandization, a wet method called electrodeposition plating that enables mass production to provide a manufacturing technology capable of providing a high-density recording medium in large quantities and at low cost. Discloses a magnetic film manufacturing technique.
しかしながら、特許文献１の先行技術の電解めっき液は、酸性の電解めっき液であり、析出物の合金比率における安定性などの点において検討する余地がある。また、湿式法によりＣｏ−Ｐｔ合金磁性膜を形成する技術開発は注目されているものの、めっき浴の種類やその条件等についてあまり多くは報告されていない。そのため、現在も、乾式法による磁性膜形成が主流であり、飛躍的な生産性の向上や低コスト化への対応が今ひとつ十分であるとはいえない状況である。 However, the prior art electrolytic plating solution of Patent Document 1 is an acidic electrolytic plating solution, and there is room for examination in terms of stability in the alloy ratio of precipitates. In addition, although technical development for forming a Co—Pt alloy magnetic film by a wet method has attracted attention, there are not many reports on the type of plating bath, its conditions, and the like. Therefore, the magnetic film formation by the dry method is still the mainstream, and it cannot be said that there is a sufficient improvement in productivity and cost reduction.
さらに、この湿式法により得られる電析めっき合金膜では、現行の磁気メディアで実現されている磁気特性、例えば保磁力の点においても、実用上十分なものといえず、湿式法によるコバルト−白金合金磁性膜を現行磁気メディアの代替材料とするには、今ひとつ満足できるものとは言えないのが現状である。 Furthermore, the electrodeposition plated alloy film obtained by this wet method cannot be said to be practically sufficient in terms of magnetic properties realized by the current magnetic media, for example, coercive force. The current situation is that it cannot be said that the alloy magnetic film is an alternative material for the current magnetic media.
本発明は、以上のような事情のもとになされたもので、磁気記録媒体として電析めっきによるコバルト−白金合金で構成し、優れた磁気特性を備えたコバルト−白金合金磁性膜を製造可能な技術を提供するものである。 The present invention has been made under the circumstances as described above, and is composed of a cobalt-platinum alloy by electrodeposition plating as a magnetic recording medium, and can produce a cobalt-platinum alloy magnetic film having excellent magnetic properties. Technology.
かかる課題を解決するため、本発明のコバルト−白金合金磁性膜の製造方法では、塩化コバルト六水和物を０．５〜２０ｇ／Ｌと、塩化白金酸（ＩＶ）を２〜６０ｇ／Ｌと、酒石酸アンモニウムを０．５〜５０ｇ／Ｌとを含有するコバルト−白金合金電析めっき浴を用いて、電析コバルト−白金合金膜を形成し、該電析コバルト−白金合金膜を２００℃〜８００℃において熱処理を行うことを特徴とするものとした。 In order to solve this problem, in the method for producing a cobalt-platinum alloy magnetic film of the present invention, cobalt chloride hexahydrate is 0.5 to 20 g / L, and chloroplatinic acid (IV) is 2 to 60 g / L. Then, using a cobalt-platinum alloy electrodeposition plating bath containing 0.5 to 50 g / L of ammonium tartrate, an electrodeposited cobalt-platinum alloy film is formed. The heat treatment is performed at 800 ° C.
本発明のＣｏ−Ｐｔ合金磁性膜の製造方法では、電析めっき浴は、塩化コバルト六水和物を０．５〜２０ｇ／Ｌと、塩化白金酸（ＩＶ）を２〜６０ｇ／Ｌと、酒石酸アンモニウムを０．５〜５０ｇ／Ｌとを含有するものを用いる。塩化コバルト六水和物は、０．５ｇ／Ｌ未満であると、コバルトが共析不可能となり、２０ｇ／Ｌを超えるとめっき液中で不安定となり、沈殿しやすくなる傾向となる。塩化白金酸（ＩＶ）は、２ｇ／Ｌ未満であると、白金が共析しづらくなり、５０ｇ／Ｌを超えるとめっき液中から塩析が発生し易くなる傾向となる。酒石酸アンモニウムは、コバルトの錯化剤の役割をし、０．５ｇ／Ｌ未満であると、コバルトが沈殿しやすくなり、５０ｇ／Ｌを超えるとめっき液中から塩析が発生し易くなる傾向となる。 In the method for producing a Co—Pt alloy magnetic film of the present invention, the electrodeposition plating bath comprises 0.5 to 20 g / L of cobalt chloride hexahydrate, 2 to 60 g / L of chloroplatinic acid (IV), What contains 0.5-50 g / L of ammonium tartrate is used. When cobalt chloride hexahydrate is less than 0.5 g / L, cobalt cannot be co-deposited, and when it exceeds 20 g / L, it becomes unstable in the plating solution and tends to precipitate. If the chloroplatinic acid (IV) is less than 2 g / L, it is difficult for the platinum to co-deposit, and if it exceeds 50 g / L, salting out tends to occur from the plating solution. Ammonium tartrate serves as a complexing agent for cobalt, and when it is less than 0.5 g / L, cobalt tends to precipitate, and when it exceeds 50 g / L, salting out tends to occur from the plating solution. Become.
そして、上述した電析めっき浴より得られた電析コバルト−白金合金膜を２００℃〜８００℃において熱処理を行うことで、合金組織をＬ１０型の規則構造に変化させることで、高い保磁力を実現することが可能となる。熱処理温度が２００℃未満であると、Ｌ１０構造への組織変化が不十分になり良好な磁気特性が実現できなくなり、８００℃を超えるとＬ１０型構造でなくなる。 Then, electrodeposited cobalt obtained from above-mentioned electrodeposition coating bath - platinum alloy film by performing a heat treatment at 200 ° C. to 800 ° C., and by changing the alloy structure in L1 0 type ordered structure, high coercivity Can be realized. If the heat treatment temperature is lower than 200 ° C., structural changes to the L1 0 structure will not be able to realize good magnetic properties becomes insufficient, no longer L1 0 type structure exceeds 800 ° C..
また、本発明の製造方法では、電析めっきの際、電流密度を１００〜２０００Ａ／ｍ２、液温５０〜７０℃とすることが好ましい。電流密度が１００Ａ／ｍ２未満であると、析出物の外観が不均一となり、２０００Ａ／ｍ２を超えると、析出物の外観が焼け状態になる傾向がある。そして、液温が５０℃未満であると白金が共析しづらくなり、７０℃を超えるとアンモニアが揮発し、めっき液の安定性が悪くなる傾向とある。 Moreover, in the manufacturing method of this invention, it is preferable that the current density shall be 100-2000 A / m < 2 > and the liquid temperature 50-70 degreeC in the case of electrodeposition plating. When the current density is less than 100 A / m 2 , the appearance of the precipitate becomes uneven, and when it exceeds 2000 A / m 2 , the appearance of the precipitate tends to be burnt. When the liquid temperature is less than 50 ° C., platinum is difficult to eutect, and when it exceeds 70 ° C., ammonia is volatilized and the stability of the plating solution tends to deteriorate.
さらに、本発明の製造方法における熱処理は、不活性雰囲気で行うことが望ましい。活性雰囲気中で熱処理を行うと酸化物となり、良好な磁気特性を有するコバルト−白金合金磁性膜を実現できなくなる。 Furthermore, the heat treatment in the production method of the present invention is desirably performed in an inert atmosphere. When heat treatment is performed in an active atmosphere, it becomes an oxide, and a cobalt-platinum alloy magnetic film having good magnetic properties cannot be realized.
本発明の製造方法では、塩化コバルト六水和物と塩化白金酸（ＩＶ）とを、コバルト：白金が７：３〜１：９としたコバルト−白金合金電析めっき浴を用い、２００℃〜８００℃の温度範囲にて熱処理を行うことが望ましい。本発明者等の研究によると、電析めっきにより得られる電析コバルト−白金合金膜におけるコバルトと白金の比が、１：１に近いものほど高い保磁力を実現できることを確認している。さらに、その後の熱処理についても、２００℃〜８００℃の温度範囲で行うと、実用的な保磁力を得ることができ、特に、６５０℃〜７５０℃の温度範囲で熱処理を行うと、より高い保磁力を実現できることを確認している。 In the production method of the present invention, cobalt chloride hexahydrate and chloroplatinic acid (IV) are used in a cobalt-platinum alloy electrodeposition plating bath in which cobalt: platinum is 7: 3 to 1: 9, and 200 ° C. to It is desirable to perform the heat treatment in a temperature range of 800 ° C. According to the study by the present inventors, it has been confirmed that a higher coercivity can be realized when the ratio of cobalt to platinum in the electrodeposited cobalt-platinum alloy film obtained by electrodeposition plating is closer to 1: 1. Further, with regard to the subsequent heat treatment, a practical coercive force can be obtained when it is carried out in the temperature range of 200 ° C. to 800 ° C., and in particular, when the heat treatment is carried out in the temperature range of 650 ° C. to 750 ° C. It has been confirmed that magnetic force can be realized.
本発明によれば、実用に適した、非常に良好な磁気特性を備えたコバルト−白金合金磁性膜を形成することが可能となる。また。５０ａｔ％Ｐｔ組成付近の電析コバルト−白金合金膜とし、７００℃の熱処理を行うことで、現行のメディアの保磁力よりも高い、約８ｋＯｅという保磁力を実現したコバルト−白金合金磁性膜を得ることができる。 According to the present invention, it is possible to form a cobalt-platinum alloy magnetic film having very good magnetic properties suitable for practical use. Also. A cobalt-platinum alloy magnetic film having a coercive force of about 8 kOe, which is higher than the coercive force of the current media, is obtained by performing a heat treatment at 700 ° C. with an electrodeposited cobalt-platinum alloy film in the vicinity of 50 at% Pt composition be able to.
以下に、本発明の好ましい実施形態について説明する。 Hereinafter, preferred embodiments of the present invention will be described.
第一実施形態：この第一実施形態では、表１に示す組成の各Ｃｏ−Ｐｔめっき浴により電析Ｃｏ−Ｐｔ合金膜を形成し、その膜構造を評価した結果について説明する。めっき浴の建浴は、まず塩化白金六水和物（Ｈ２ＰｔＣｌ６・６Ｈ２Ｏ）を６０℃に温めた５％アンモニア水（ＮＨ３・Ｈ２Ｏ）に添加し、透明な黄色になるまで溶解させた（約２４時間）白金溶液を作製した。また、別のビーカーに塩化コバルト六水和物（ＣｏＣｌ２・６Ｈ２Ｏ）を蒸留水で溶解し、酒石酸アンモニウムを添加し、紫色の白濁溶液になるまで放置し、コバルト溶液を作製した。このとき、白金溶液とコバルト溶液とのｐＨはそれぞれｐＨ９、ｐＨ５であり、このまま混合させると沈殿が生じる可能性があるため、コバルト溶液にアンモニア水を添加してｐＨ９に調整し、このｐＨ調整したコバルト溶液を白金溶液中に添加して、Ｃｏ−Ｐｔめっき液を建浴した。尚、ｐＨ９に調整したコバルト溶液は透明な紫色となった。 First Embodiment: In this first embodiment, the results of forming an electrodeposited Co—Pt alloy film with each Co—Pt plating bath having the composition shown in Table 1 and evaluating the film structure will be described. Vatting of the plating bath is first added to the platinum chloride hexahydrate (H 2 PtCl 6 · 6H 2 O) 5% ammonia water warmed to 60 ℃ (NH 3 · H 2 O), the clear yellow A platinum solution was prepared until dissolved (about 24 hours). In another beaker, cobalt chloride hexahydrate (CoCl 2 · 6H 2 O) was dissolved in distilled water, ammonium tartrate was added, and the mixture was allowed to stand until it became a purple cloudy solution to prepare a cobalt solution. At this time, the pH of the platinum solution and the cobalt solution is pH 9 and pH 5, respectively, and if mixed as they are, precipitation may occur. Therefore, ammonia water was added to the cobalt solution to adjust to pH 9, and the pH was adjusted. A cobalt solution was added to the platinum solution to form a Co-Pt plating solution. In addition, the cobalt solution adjusted to pH 9 became transparent purple.
上述した建浴法により、表１に示す各組成のＣｏ−Ｐｔめっき浴を準備し、チタン製のメッシュコーティングがされたＰｔアノード電極と、Ｃｕカソード電極（３５μｍ厚の銅箔を圧延銅板で裏打ちし、リン酸溶液にて銅箔表面を電解研磨して鏡面仕上げしたもの）とを用いて電析めっきすることで行った。めっき処理条件は、液温６０℃、電流密度を１００〜２０００Ａ／ｍ２の範囲で変化させて様々な組成の電析Ｃｏ−Ｐｔ合金膜を形成した。Ｃｏ−Ｐｔめっき浴のｐＨは無調整でめっきを行ったが、表１の各組成でほぼｐＨ９であった。また、電気量は１０Ｃ／ｃｍ２とした。さらに、沈殿を防ぐため、電析中にめっき液の撹拌を行った。 Co-Pt plating baths having the compositions shown in Table 1 were prepared by the above-described bathing method, and a titanium mesh-coated Pt anode electrode and a Cu cathode electrode (35 μm thick copper foil lined with a rolled copper plate) Then, the surface of the copper foil was electropolished with a phosphoric acid solution and mirror finished). Plating conditions were such that the electrode temperature was 60 ° C. and the current density was changed in the range of 100 to 2000 A / m 2 to form electrodeposited Co—Pt alloy films having various compositions. Although the plating was performed without adjusting the pH of the Co—Pt plating bath, the pH was substantially 9 for each composition shown in Table 1. The amount of electricity was 10 C / cm 2 . Furthermore, in order to prevent precipitation, the plating solution was stirred during electrodeposition.
図１には、実施例１〜４の各めっき浴において各電流密度で得られた電析Ｃｏ−Ｐｔ合金膜について、膜中のＰｔ濃度（ａｔ％）を測定し、Ｐｔ濃度と電流密度との関係を示したものである。合金膜組成の分析は、エネルギー分散型Ｘ線分光装置（ＥＤＳ）で測定した。図１を見ると判るように、膜中のＰｔ濃度はめっき浴のＰｔ濃度の増加に伴って増加することが確認された。そして、膜中のＰｔ濃度は浴中のＰｔ濃度より常に低いことが判明した。また、図１の傾向により、各実施例のめっき浴ではＣｏよりもＰｔの方が析出しにくいことが分かるので、いわゆる異常析出型であることが確認された。図１の結果より、本実施例のＣｏ−Ｐｔめっき浴を用いた電析法によれば、９．９ａｔ％〜６０．５ａｔ％Ｐｔ組成のＣｏ−Ｐｔ合金膜を得ることができることが判明した。 In FIG. 1, the Pt concentration (at%) in the film was measured for the electrodeposited Co—Pt alloy film obtained at each current density in each plating bath of Examples 1 to 4, and the Pt concentration and current density were measured. This shows the relationship. The analysis of the alloy film composition was measured with an energy dispersive X-ray spectrometer (EDS). As can be seen from FIG. 1, it was confirmed that the Pt concentration in the film increased as the Pt concentration in the plating bath increased. It was found that the Pt concentration in the film was always lower than the Pt concentration in the bath. In addition, it can be seen from the tendency of FIG. 1 that Pt is less liable to precipitate than Co in the plating bath of each example, so that it was confirmed to be a so-called abnormal precipitation type. From the results of FIG. 1, it was found that a Co—Pt alloy film having a composition of 9.9 at% to 60.5 at% Pt can be obtained by the electrodeposition method using the Co—Pt plating bath of this example. .
次に、得られたＣｏ−Ｐｔ合金膜の化学結合状態を調査した結果について説明する。図２には、３７．２ａｔ％Ｐｔ組成（実施例３、電流密度４００Ａ／ｍ２）のＣｏ−Ｐｔ合金膜をＸ線光電子分析装置（ＥＳＣＡ）により分析した結果を示している。このＥＳＣＡ分析では合金膜表面の汚染や酸化物の影響を避けるため、合金膜表面のアルゴンイオンエッチング（電圧１０ｋＶ、電流０．５ｍＡ）を１ｍｉｎ、５ｍｉｎ、１０ｍｉｎ間行い、膜中の化学結合状態を測定した。図２は、合金膜中のＣｏ２ｐ及びＰｔ４ｆのＥＳＣＡスペクトルを示している。図２のＣｏ２ｐのスペクトルから、エッチングを行っていないａｓ−ｄｅｐｏｓｉｔｅｄのものでは、Ｃｏの金属状態は確認できなかったが、１ｍｉｎ間以上のエッチングを行うことでＣｏの金属状態が確認された。ａｓ−ｄｅｐｏｓｉｔｅｄでは、膜表面の汚染や酸化物の影響によりＣｏの金属状態が確認できなかったものと考えられた。一方、Ｐｔ４ｆのスペクトルでは、エッチングを行っていないａｓ−ｄｅｐｏｓｉｔｅｄのものからＰｔが金属状態であることが確認された。この結果、３７．２ａｔ％Ｐｔ組成のＣｏ−Ｐｔ合金膜は金属状態の合金膜であることが分かり、エッチング時間に関わらずＣｏ及びＰｔの金属状態であることが確認されたことから、膜厚方向で化学結合状態は一様であることが明らかとなった。 Next, the result of investigating the chemical bonding state of the obtained Co—Pt alloy film will be described. FIG. 2 shows the result of analyzing a Co—Pt alloy film having a 37.2 at% Pt composition (Example 3, current density of 400 A / m 2 ) using an X-ray photoelectron analyzer (ESCA). In this ESCA analysis, argon ion etching (voltage 10 kV, current 0.5 mA) of the alloy film surface is performed for 1 min, 5 min, and 10 min in order to avoid contamination of the alloy film surface and oxides, and the chemical bonding state in the film is determined. It was measured. FIG. 2 shows ESCA spectra of Co2p and Pt4f in the alloy film. From the Co2p spectrum of FIG. 2, the as-deposited one in which etching was not performed could not confirm the metal state of Co, but the metal state of Co was confirmed by performing etching for 1 min or longer. In as-deposited, it was considered that the metal state of Co could not be confirmed due to the contamination of the film surface and the influence of oxides. On the other hand, in the spectrum of Pt4f, it was confirmed that Pt was in a metal state from as-deposited ones that were not etched. As a result, it was found that the Co—Pt alloy film having a composition of 37.2 at% Pt was an alloy film in a metal state, and it was confirmed that it was in a metal state of Co and Pt regardless of the etching time. It became clear that the chemical bonding state was uniform in the direction.
続いて、電析Ｃｏ−Ｐｔ合金膜の結晶光学的構造を調査した結果について説明する。膜構造は、Ｘ線回折装置（ＸＲＤ）により連続法を用いて測定した。測定条件は、Ｃｕ−Ｋα線を用い、管電圧４０ｋＶ、管電流３００ｍＡとし、測定範囲を２０°〜９０°とした。上記した電析Ｃｏ−Ｐｔ合金膜のうち、８種類のＰｔ組成のものを選択してＸＲＤによりその構造を分析した。その結果を図３に示す。分析した合金膜は、（ａ）１６．５ａｔ％Ｐｔ（実施例４、電流密度４００Ａ／ｍ２）、（ｂ）２５．１ａｔ％Ｐｔ（実施例４、電流密度６００Ａ／ｍ２）、（ｃ）３１．１ａｔ％Ｐｔ（実施例４、電流密度１５００Ａ／ｍ２）、（ｄ）３５．７ａｔ％Ｐｔ（実施例２、電流密度１０００Ａ／ｍ２）、（ｅ）４１．４ａｔ％Ｐｔ（実施例２、電流密度６００Ａ／ｍ２）、（ｆ）４５．６ａｔ％Ｐｔ（実施例３、電流密度１５００Ａ／ｍ２）、（ｇ）５１．１ａｔ％Ｐｔ（実施例２、電流密度１５００Ａ／ｍ２）、（ｈ）５６．８ａｔ％Ｐｔ（実施例１、電流密度８００Ａ／ｍ２）の８種類である。 Next, the results of investigating the crystal optical structure of the electrodeposited Co—Pt alloy film will be described. The film structure was measured by an X-ray diffractometer (XRD) using a continuous method. The measurement conditions were Cu-Kα rays, tube voltage 40 kV, tube current 300 mA, and measurement range 20 ° to 90 °. Of the above-described electrodeposited Co—Pt alloy films, eight kinds of Pt compositions were selected and the structures thereof were analyzed by XRD. The result is shown in FIG. The analyzed alloy films were (a) 16.5 at% Pt (Example 4, current density 400 A / m 2 ), (b) 25.1 at% Pt (Example 4, current density 600 A / m 2 ), (c 31.1 at% Pt (Example 4, current density 1500 A / m 2 ), (d) 35.7 at% Pt (Example 2, current density 1000 A / m 2 ), (e) 41.4 at% Pt (implemented) Example 2, current density 600 A / m 2 ), (f) 45.6 at% Pt (Example 3, current density 1500 A / m 2 ), (g) 51.1 at% Pt (Example 2, current density 1500 A / m) 2 ), (h) 56.8 at% Pt (Example 1, current density 800 A / m 2 ).
図３より、Ｐｔ濃度が１６．５〜３１．１ａｔ％の組成範囲では、２つの鋭い回折ピークが２θ＝４０．０°、４５．８°付近に現れており、これらの回折ピークは六方晶構造をとるε−Ｃｏによるものであると考えられる。これらの回折ピークは膜中のＰｔ濃度の増加に伴い低角度側にシフトしており、ε−Ｃｏ格子中にＰｔが固溶した（ε−Ｃｏ，Ｐｔ）固溶体によるものと考えられた。そして、膜中のＰｔ濃度が３５．７ａｔ％以上になると１つの鋭い回折ピーク（２θ＝４１．９°）と比較的ブロードな回折ピーク（２θ＝４８．５°）が（ε−Ｃｏ，Ｐｔ）固溶体の回折ピークと共に現れ始め、これらの回折ピークはＰｔ又は立方晶構造をとるα−Ｃｏによるものと考えられた。これらの回折ピークも上述した（ε−Ｃｏ，Ｐｔ）固溶体の回折ピークと同様に、膜中のＰｔ濃度の増加に伴い低角度側にシフトしていたことからα−Ｃｏ格子中にＰｔが固溶した（α−Ｃｏ，Ｐｔ）固溶体によるものと考えられた。一方、（ε−Ｃｏ，Ｐｔ）固溶体の回折ピークは膜中のＰｔ濃度が増加するに従って次第に弱くなり、５１．１ａｔ％Ｐｔ組成になると（ε−Ｃｏ，Ｐｔ）固溶体の回折ピークは観察されなくなった。膜中のＰｔ濃度が高い５１．１〜５６．８ａｔ％Ｐｔの組成範囲では、（α−Ｃｏ，Ｐｔ）固溶体を示す回折ピークのみが現れており、この回折ピークも膜中のＰｔ濃度の増加に伴って低角度側にシフトしていた。 From FIG. 3, in the composition range where the Pt concentration is 16.5 to 31.1 at%, two sharp diffraction peaks appear in the vicinity of 2θ = 40.0 ° and 45.8 °, and these diffraction peaks are hexagonal crystals. It is thought to be due to ε-Co taking a structure. These diffraction peaks were shifted to the lower angle side as the Pt concentration in the film increased, and it was considered that this was due to the (ε-Co, Pt) solid solution in which Pt was dissolved in the ε-Co lattice. When the Pt concentration in the film is 35.7 at% or more, one sharp diffraction peak (2θ = 41.9 °) and a relatively broad diffraction peak (2θ = 48.5 °) are (ε-Co, Pt ) It began to appear with the diffraction peaks of the solid solution, and these diffraction peaks were thought to be due to Pt or α-Co having a cubic structure. Similar to the diffraction peak of the (ε-Co, Pt) solid solution described above, these diffraction peaks were shifted to a lower angle side as the Pt concentration in the film increased, so that Pt was solidified in the α-Co lattice. It was thought to be due to the dissolved (α-Co, Pt) solid solution. On the other hand, the diffraction peak of the (ε-Co, Pt) solid solution gradually weakens as the Pt concentration in the film increases, and when the 51.1 at% Pt composition is reached, the diffraction peak of the (ε-Co, Pt) solid solution is not observed. It was. In the composition range of 51.1 to 56.8 at% Pt where the Pt concentration in the film is high, only the diffraction peak indicating the (α-Co, Pt) solid solution appears, and this diffraction peak also increases the Pt concentration in the film. Along with this, it shifted to the low angle side.
この図３に示す結果から、本実施形態での電析Ｃｏ−Ｐｔ合金膜が固溶体を形成しているかを確認するため、図３の回折ピークから各組成の（ε−Ｃｏ，Ｐｔ）固溶体の格子定数を算出し、膜中のＰｔ濃度と格子定数との関係を調べた。その結果を図４に示す。図４を見ると判るように、Ｐｔ濃度の増加に伴って（ε−Ｃｏ，Ｐｔ）のa軸の格子定数が増加していることから、膜中のＰｔ濃度が低いものでは（ε−Ｃｏ，Ｐｔ）固溶体を形成していることが判明した。同様に、図３の回折ピークから各組成の（α−Ｃｏ，Ｐｔ）固溶体の格子定数を算出し、膜中のＰｔ濃度と格子定数との関係を調べた。その結果を図５に示す。図５を見ると判るように、本実施形態のＣｏ−Ｐｔ合金膜の格子定数はＰｔ濃度の増加に伴って増加していることが判明した。またこれらの格子定数は純α−Ｃｏと純Ｐｔとの格子定数とを結んだＶｅｇａｒｄ則から得られる直線にほぼ一致し、（α−Ｃｏ，Ｐｔ）固溶体を形成していることが確認された。以上の構造解析より、本実施形態で作製した電析Ｃｏ−Ｐｔ合金膜は、３１．１ａｔ％Ｐｔ以下の組成では（ε−Ｃｏ，Ｐｔ）固溶体であり、３５．７〜４５．６ａｔ％Ｐｔ以下の組成範囲では（α−Ｃｏ，Ｐｔ）固溶体と（ε−Ｃｏ，Ｐｔ）固溶体との２相が存在し、さらに５１．１ａｔ％Ｐｔ以上の組成では（α−Ｃｏ，Ｐｔ）固溶体であることが判明した。Ｃｏ−Ｐｔ合金の熱平衡状態図によれば、常温付近ではＣｏＰｔやＣｏＰｔ３やその混合相が安定相となっているが、本実施形態で作製した電析Ｃｏ−Ｐｔ合金膜は、高温で安定な相（α−Ｃｏ，Ｐｔ）や熱平衡状態図に存在しない（ε−Ｃｏ，Ｐｔ）を形成しており、準安定相をとる構造であることが分かった。 From the results shown in FIG. 3, in order to confirm whether the electrodeposited Co—Pt alloy film in this embodiment forms a solid solution, the (ε-Co, Pt) solid solution of each composition is determined from the diffraction peak of FIG. The lattice constant was calculated, and the relationship between the Pt concentration in the film and the lattice constant was examined. The result is shown in FIG. As can be seen from FIG. 4, since the lattice constant of the a axis of (ε-Co, Pt) increases as the Pt concentration increases, (ε-Co in the case where the Pt concentration in the film is low) , Pt) was found to form a solid solution. Similarly, the lattice constant of the (α-Co, Pt) solid solution of each composition was calculated from the diffraction peak of FIG. 3, and the relationship between the Pt concentration in the film and the lattice constant was examined. The result is shown in FIG. As can be seen from FIG. 5, it was found that the lattice constant of the Co—Pt alloy film of the present embodiment increased as the Pt concentration increased. In addition, these lattice constants almost coincided with the straight line obtained from the Vegard law connecting the lattice constants of pure α-Co and pure Pt, and it was confirmed that (α-Co, Pt) solid solution was formed. . From the above structural analysis, the electrodeposited Co—Pt alloy film produced in this embodiment is an (ε-Co, Pt) solid solution with a composition of 31.1 at% Pt or less, and 35.7 to 45.6 at% Pt. In the following composition range, there are two phases of (α-Co, Pt) solid solution and (ε-Co, Pt) solid solution, and in the composition of 51.1 at% Pt or more, it is (α-Co, Pt) solid solution. It has been found. According to the thermal equilibrium diagram of the Co—Pt alloy, CoPt, CoPt 3 and their mixed phases are stable near room temperature, but the electrodeposited Co—Pt alloy film produced in this embodiment is stable at high temperature. It has been found that this is a structure having a metastable phase (α-Co, Pt) and (ε-Co, Pt) not present in the thermal equilibrium diagram.
さらに、本実施形態で作製した電析Ｃｏ−Ｐｔ合金膜の表面形態を走査型電子顕微鏡（ＳＥＭ）により観察した結果を説明する。図３で示した８種類のＣｏ−Ｐｔ合金膜について、ＳＥＭにより倍率６５０００倍でその表面を観察した。図６には、上記（ａ）〜（ｆ）の６種の観察結果を示す。その結果、組成の変化に関わらず膜表面は凹凸無い形態であることが確認された。また、高電流密度の作製した膜の場合、若干凹凸が観察されたが、全ての組成で非常に光沢性の良い膜であることが確認された。 Furthermore, the result of having observed the surface form of the electrodeposited Co-Pt alloy film produced by this embodiment with the scanning electron microscope (SEM) is demonstrated. The surfaces of the eight types of Co—Pt alloy films shown in FIG. 3 were observed by SEM at a magnification of 65,000 times. FIG. 6 shows the six types of observation results (a) to (f). As a result, it was confirmed that the film surface had no irregularities regardless of the change in composition. In addition, in the case of a film produced with a high current density, some unevenness was observed, but it was confirmed that the film was very glossy with all compositions.
さらに続いて、本実施形態で作製した電析Ｃｏ−Ｐｔ合金膜の結晶粒径及びその構造解析を高分解能透過型電子顕微鏡（ＨＲＴＥＭ）により調査した結果を説明する。ＨＲＴＥＭ観察用試料は、ダイヤモンドペーストを用いたディンプリングにより１０μｍ程度にまで薄くした後、イオンミリング（加速電圧５ｋＶ、電流５ｍＡ）により、１５°傾斜させた試料台の基板側からのみＡｒイオンを照射して作製した。ＴＥＭ観察は、図３で示した８種類の組成のＣｏ−Ｐｔ合金膜について行った（図７）。図７の格子像から、各組成のＣｏ−Ｐｔ合金膜は、その結晶粒界がはっきりと観察され、非常に微細な結晶より構成されていることが判った。また、膜中のＰｔ濃度の増加に伴い、結晶粒径は小さくなる傾向が見られ、５０ａｔ％Ｐｔ組成付近の膜では、結晶粒径が約５ｎｍとなることが確認された。この図７に示す格子像の結果より、本実施形態で作製した電析Ｃｏ−Ｐｔ合金膜の結晶粒径が約５〜１０ｎｍ程度であり、微細な粒子により構成されていることが判明した。また、電子線回折図形からＡｕの標準回折図形を用いてＣｏ−Ｐｔ合金膜の構造解析を行ったところ、１６．５ａｔ％Ｐｔ組成の膜では（ε−Ｃｏ，Ｐｔ）固溶体を示す回折環が現れており、２５．１〜３５．７ａｔ％Ｐｔ組成の膜では（ε−Ｃｏ，Ｐｔ）固溶体及び（α−Ｃｏ，Ｐｔ）固溶体を示す回折環が現れており、これら２相が存在していることが確認された。そして、４１．４ａｔ％以上のＰｔ組成の膜では（α−Ｃｏ，Ｐｔ）固溶体を示す回折環のみが現れていることが確認できた。この結果、上述したＸＲＤによる構造解析結果と若干相違するものであるが、Ｐｔ濃度のその構造との関係はＸＲＤの場合とほぼ同様の傾向を示すことが確認できた。 Subsequently, the results of investigating the crystal grain size and structural analysis of the electrodeposited Co—Pt alloy film produced in this embodiment using a high-resolution transmission electron microscope (HRTEM) will be described. The sample for HRTEM observation was irradiated with Ar ions only from the substrate side of the sample stage tilted by 15 ° by ion milling (acceleration voltage 5 kV, current 5 mA) after being thinned to about 10 μm by dipping using diamond paste. And produced. The TEM observation was performed on the Co—Pt alloy films having the eight kinds of compositions shown in FIG. 3 (FIG. 7). From the lattice image of FIG. 7, it was found that the Co—Pt alloy film of each composition was composed of very fine crystals, with its crystal grain boundaries clearly observed. In addition, the crystal grain size tended to decrease as the Pt concentration in the film increased, and it was confirmed that the crystal grain size was about 5 nm in the film near the 50 at% Pt composition. From the result of the lattice image shown in FIG. 7, it was found that the crystal grain size of the electrodeposited Co—Pt alloy film produced in this embodiment is about 5 to 10 nm, and is composed of fine particles. In addition, when the structural analysis of the Co—Pt alloy film was performed from the electron diffraction pattern using the standard diffraction pattern of Au, the diffraction ring showing (ε-Co, Pt) solid solution was found in the film of 16.5 at% Pt composition. A diffractive ring showing (ε-Co, Pt) solid solution and (α-Co, Pt) solid solution appears in the film of 25.1 to 35.7 at% Pt composition, and these two phases exist. It was confirmed that It was confirmed that only the diffraction ring showing the (α-Co, Pt) solid solution appeared in the film having a Pt composition of 41.4 at% or more. As a result, although slightly different from the above-described structural analysis result by XRD, it was confirmed that the relationship between the Pt concentration and the structure showed almost the same tendency as in the case of XRD.
さらに加えて、熱処理による電析Ｃｏ−Ｐｔ合金膜の構造変化を調べた結果について説明する。この熱処理試験は、サンプルとして５１．１ａｔ％Ｐｔ組成の膜を用い、熱処理により常温で準安定なＬ１０構造に変化するかどうかを調査した。熱処理は、赤外線加熱炉を用い、真空雰囲気中、４５０℃、６０ｍｉｎ間熱処理後、空冷により冷却した。図８に、熱処理前後の合金膜についてＸＲＤにより回折パターンを測定した結果を示す。ＸＲＤの測定条件は、図３で説明した場合と同様である。図８を見ると判るように、熱処理前のａｓ−ｄｅｐｏｓｉｔｅｄの膜では、（α−Ｃｏ，Ｐｔ）固溶体の回折ピークが現れていたのに対して、熱処理後のものは（００１），（１１０）などのＬ１０構造の存在を示す超格子の回折ピークが現れていた。この結果により、５１．１ａｔ％Ｐｔ組成の合金膜は、熱処理により、（α−Ｃｏ，Ｐｔ）固溶体からＬ１０構造に変化することが確認された。しかし、このＸＲＤの回折ピークのうち、Ｌ１０構造以外にＣｕ３Ｐｔを示す回折ピークが現れていたが、これは熱処理の際に、基板に用いた銅箔のＣｕがＣｏ−Ｐｔ合金膜中に拡散し、Ｐｔと金属間化合物を形成したためと考えられる。尚、２３°付近に現れている回折ピークは試料固定する際の両面テープのために現れたものである。 In addition, the results of examining the structural change of the electrodeposited Co—Pt alloy film by heat treatment will be described. This heat treatment test, using a film of 51.1at% Pt composition as a sample, it was investigated whether changes to the metastable L1 0 structure at normal temperature by heat treatment. The heat treatment was performed by air cooling using an infrared heating furnace after heat treatment at 450 ° C. for 60 minutes in a vacuum atmosphere. In FIG. 8, the result of having measured the diffraction pattern by XRD about the alloy film before and behind heat processing is shown. The XRD measurement conditions are the same as those described with reference to FIG. As can be seen from FIG. 8, in the as-deposited film before the heat treatment, the diffraction peak of the (α-Co, Pt) solid solution appeared, whereas in the as-deposited film, the one after the heat treatment is (001), (110 ) diffraction peak of the superlattice indicating the presence of L1 0 structures such as had appeared. This result, an alloy film of 51.1at% Pt composition, heat treatment, it was confirmed that changes in the L1 0 structure from (α-Co, Pt) solid solution. However, among the diffraction peaks of the XRD, L1 0 although the diffraction peak indicating Cu 3 Pt in addition structure was appeared, which during heat treatment, the copper foil Cu is Co-Pt alloy film used for the substrate This is considered to be because Pt and an intermetallic compound were formed. Incidentally, the diffraction peak appearing near 23 ° appears due to the double-sided tape when the sample is fixed.
図８で説明した熱処理後の電析Ｃｏ−Ｐｔ合金膜をＨＲＴＥＭによりその構造解析を行った（図９）。図９に示す格子像と電子線回折図形より、熱処理前のａｓ−ｄｅｐｏｓｉｔｅｄの膜では、図７の場合と同様に、はっきりとした粒界が観察され、約５ｎｍ程度の粒径であることが判った。そして、電子線回折図形より（α−Ｃｏ，Ｐｔ）固溶体構造であった。一方、熱処理後のものでは、Ｌ１０構造をもつＣｏＰｔ粒子の粒界は観察されなかったが、電子線回折図形の解析結果から、（１１１）よりも内側に（００１），（１１０）に関する回折斑点が確認できたのでＬ１０構造を呈していることが判明した。但し、このＨＲＴＥＭによる電子線回折図形からも、ＸＲＤ分析と同様にＣｕ３Ｐｔを示す回折環がＬ１０構造を示す回折環よりも強く現れていた。 The structure of the electrodeposited Co—Pt alloy film after the heat treatment described in FIG. 8 was analyzed by HRTEM (FIG. 9). From the lattice image and electron diffraction pattern shown in FIG. 9, in the as-deposited film before the heat treatment, a clear grain boundary is observed as in FIG. 7, and the particle size is about 5 nm. understood. And it was ((alpha) -Co, Pt) solid solution structure from the electron beam diffraction pattern. On the other hand, those of the later heat treatment, but the grain boundaries of the CoPt particles having an L1 0 structure was observed, from the analysis result of the electron beam diffraction pattern, (111) inside the (001) diffraction relates (110) since the spots could be confirmed was found that the shape of a L1 0 structure. However, from the electron beam diffraction pattern by the HRTEM, diffraction rings exhibit similarly Cu 3 Pt and XRD analysis was appeared stronger than the diffraction rings show an L1 0 structure.
最後に、本実施形態で作製した電析Ｃｏ−Ｐｔ合金膜について、熱処理前後の磁気ヒステリシス曲線を測定した結果を説明する。この磁気ヒステリシス曲線の測定は、サンプルとして５１．１ａｔ％Ｐｔ組成の膜を用い、振動式試料型磁力計（ＶＳＭ）を用い、室温、−２０ｋＯｅ〜２０ｋＯｅの外部磁化をかけながら測定した。また、Ｌ１０型ＣｏＰｔ合金が膜方向でなく垂直方向に高い磁気異方性を持つため、外部磁場は試料に対して垂直方向にかけて行った。図１０に、測定した磁気ヒステリシス曲線を示す。図１０に示すように、熱処理を行っていないａｓ−ｄｅｐｏｓｉｔｅｄの膜では、保磁力Ｈｃ＝７４Ｏｅという非常に小さな値であったが、熱処理後のＬ１０構造に変化したものでは、保磁力Ｈｃ＝６７３Ｏｅという、熱処理前の約９倍にも増大していた。しかし、この熱処理後の数値は、従来から報告されているＬ１０型ＣｏＰｔ合金の値としては不十分なもので、この結果は上述したようにＣｏ−Ｐｔ合金膜中に銅箔のＣｕが拡散し、Ｐｔと金属間化合物を形成したためと考えられた。 Finally, the results of measuring the magnetic hysteresis curve before and after the heat treatment for the electrodeposited Co—Pt alloy film produced in this embodiment will be described. The magnetic hysteresis curve was measured using a film having a 51.1 at% Pt composition as a sample and using a vibrating sample magnetometer (VSM) while applying external magnetization of −20 kOe to 20 kOe at room temperature. Also, L1 0 type CoPt alloy due to its high magnetic anisotropy in the vertical direction rather than film direction, the external magnetic field was carried over in the direction perpendicular to the sample. FIG. 10 shows the measured magnetic hysteresis curve. As shown in FIG. 10, in the film as-deposited not subjected to heat treatment, but was a very small value of the coercive force Hc = 74Oe, it is obtained by changing the L1 0 structure after heat treatment, the coercive force Hc = It increased to 673 Oe, which was about 9 times that before the heat treatment. However, numerical values after the heat treatment, the value of L1 0 type CoPt alloys have been reported conventionally unsatisfactory, this result Cu of the copper foil during CoPt alloy film as described above diffuses It was thought that this was because an intermetallic compound was formed with Pt.
第二実施形態：この第二実施形態では、上記した第一実施形態の結果を踏まえ、ＣｏやＰｔとの金属間化合物を形成しない基板材料を選択し、本発明の電析Ｃｏ−Ｐｔ合金膜の磁性特性を調査した。本実施形態では、（００１）面を表面に持つ、単結晶シリコンウエハを基板として用いた。この基板を選択したのは、シリコンがコバルトや白金に固溶しない物質で、且つ、ＣｏＰｔ合金がｃ軸方向に高い垂直磁気異方性をもつ性質があり、より大きな磁気特性を実現できることが期待されたためである。用いたシリコンウエハ基板の概要を表２に示す。 Second Embodiment: In this second embodiment, based on the result of the first embodiment described above, a substrate material that does not form an intermetallic compound with Co or Pt is selected, and the electrodeposited Co—Pt alloy film of the present invention. The magnetic properties of were investigated. In this embodiment, a single crystal silicon wafer having a (001) plane on the surface is used as the substrate. This substrate was selected because silicon is a substance that does not dissolve in cobalt and platinum, and the CoPt alloy has a high perpendicular magnetic anisotropy in the c-axis direction, and it is expected that greater magnetic properties can be realized. It was because it was done. Table 2 shows an outline of the silicon wafer substrate used.
表２示すシリコンウエハ基板はそのままの状態では密着性が悪いため、次の前処理を行った後に、その表面へ電析Ｃｏ−Ｐｔ合金膜を被覆した。前処理は１０ｗｔ％ＨＦ溶液中にシリコンウエハを１０分間浸漬し酸化皮膜を除去した後、密着性を向上させるためＣｒをスパッタリング法によりイオンシャワー装置を用いて１ｍｉｎ間成膜し、さらに導電性を付与すべくＣｒと同様にＰｔをスパッタリング法により３ｍｉｎ間成膜した。このようにＣｒとＰｔとを成膜したシリコンウエハをマスキングテープで１０ｍｍ×２０ｍｍになるように、周辺部及び裏面を絶縁した基板とした。 Since the silicon wafer substrate shown in Table 2 has poor adhesion in the state as it is, the surface was coated with an electrodeposited Co—Pt alloy film after the following pretreatment. In the pretreatment, a silicon wafer is immersed in a 10 wt% HF solution for 10 minutes to remove the oxide film, and then Cr is formed by sputtering using an ion shower apparatus for 1 minute in order to improve adhesion, and further conductivity is increased. In order to apply, Pt was deposited for 3 minutes by sputtering as with Cr. The silicon wafer on which the Cr and Pt films were formed in this manner was used as a substrate with the peripheral portion and the back surface insulated so as to be 10 mm × 20 mm with a masking tape.
本実施形態で用いたＣｏ−Ｐｔめっき浴は、上記第一実施形態の表１に示す実施例１及び実施例２のものを用いた。これは５０ａｔ％Ｐｔ組成のＣｏ−Ｐｔ合金膜が得られやすいようにするためである。めっき浴の製造法やめっき条件については第一実施形態と同様である。ここでは、まず、電流密度を５００〜２００と変化させて、５０ａｔ％Ｐｔ組成の電析Ｃｏ−Ｐｔ合金膜をシリコンウエハ上に作製し、その組成を確認した。膜組成の測定法は第一実施形態と同じである。図１１に電流密度と膜組成との関係を示す。 As the Co—Pt plating bath used in the present embodiment, those of Examples 1 and 2 shown in Table 1 of the first embodiment were used. This is to make it easy to obtain a Co—Pt alloy film having a 50 at% Pt composition. The method for producing the plating bath and the plating conditions are the same as in the first embodiment. Here, first, an electrodeposited Co—Pt alloy film having a 50 at% Pt composition was produced on a silicon wafer while changing the current density from 500 to 200, and the composition was confirmed. The method for measuring the film composition is the same as in the first embodiment. FIG. 11 shows the relationship between current density and film composition.
図１１を見ると判るように、実施例１（Ｐｔ濃度０．０４５Ｍ）、実施例２（Ｐｔ濃度０．０３５Ｍ）を用いて、電流密度を変化させてＣｏ−Ｐｔ合金膜を作製したところ、シリコンウエハ基板上に５０ａｔ％Ｐｔ組成付近のものを作製することができた。 As can be seen from FIG. 11, when the current density was changed using Example 1 (Pt concentration 0.045M) and Example 2 (Pt concentration 0.035M), a Co—Pt alloy film was produced. A silicon wafer substrate with a composition around 50 at% Pt could be produced.
次に、作製した電析Ｃｏ−Ｐｔ合金膜の結晶光学的構造を調査した結果について説明する。構造は、Ｘ線回折装置（ＸＲＤ）により連続法を用いて測定した。測定条件は、第一実施形態と同じである。作製した電析Ｃｏ−Ｐｔ合金膜のうち、５種類のＰｔ組成のものを選択してＸＲＤによりその構造を分析した。その結果を図１２に示す。分析した合金膜は、（ｉ）４３．６ａｔ％Ｐｔ（実施例２、電流密度８００Ａ／ｍ２）、（ｊ）４４．９ａｔ％Ｐｔ（実施例２、電流密度１２００Ａ／ｍ２）、（ｋ）４６．７ａｔ％Ｐｔ（実施例４、電流密度１５００Ａ／ｍ２）、（ｌ）４９．３ａｔ％Ｐｔ（実施例４、電流密度２０００Ａ／ｍ２）、（ｍ）５１．８ａｔ％Ｐｔ（実施例１、電流密度１５００Ａ／ｍ２）の５種類である。 Next, the result of investigating the crystal optical structure of the deposited electrodeposited Co—Pt alloy film will be described. The structure was measured using a continuous method with an X-ray diffractometer (XRD). The measurement conditions are the same as in the first embodiment. Of the produced electrodeposited Co—Pt alloy films, five types of Pt compositions were selected and their structures were analyzed by XRD. The result is shown in FIG. The analyzed alloy films were (i) 43.6 at% Pt (Example 2, current density 800 A / m 2 ), (j) 44.9 at% Pt (Example 2, current density 1200 A / m 2 ), (k ) 46.7 at% Pt (Example 4, current density 1500 A / m 2 ), (l) 49.3 at% Pt (Example 4, current density 2000 A / m 2 ), (m) 51.8 at% Pt (implementation) Example 1 and current density of 1500 A / m 2 ).
図１２中、３９°付近に現れているピークは基板に成膜させたＰｔ（１１１）の回折ピークであり、６９°付近に現れているピークはＳｉ（４００）回折ピークである。この図１２を見ると判るように、２θ＝４１．９°、４８．５°付近に（α−Ｃｏ，Ｐｔ）固溶体の回折ピークが確認された。従って、本実施形態の電析Ｃｏ−Ｐｔ合金膜は、Ｃｕ基板を用いた第一実施形態と同様に、５０ａｔ％Ｐｔ組成付近では（α−Ｃｏ，Ｐｔ）固溶体を形成していることが判った。 In FIG. 12, the peak appearing near 39 ° is the diffraction peak of Pt (111) deposited on the substrate, and the peak appearing near 69 ° is the Si (400) diffraction peak. As can be seen from FIG. 12, diffraction peaks of (α-Co, Pt) solid solution were confirmed in the vicinity of 2θ = 41.9 ° and 48.5 °. Therefore, it can be seen that the electrodeposited Co—Pt alloy film of this embodiment forms an (α-Co, Pt) solid solution in the vicinity of the 50 at% Pt composition, as in the first embodiment using the Cu substrate. It was.
続いて、熱処理温度変化による電析Ｃｏ−Ｐｔ合金膜の構造変化を調べた結果について説明する。この熱処理試験は、サンプルとして上記（ｉ）〜（ｍ）の５種類の合金膜を用い、真空雰囲気中、熱処理温度５００℃、６００℃、７００℃の各温度で熱処理し、それぞれの構造変化を調査した。その結果を図１３（（ｉ）、（ｊ）、（ｋ））、図１４（（ｌ）、（ｍ））に示す。 Then, the result of having investigated the structural change of the electrodeposition Co-Pt alloy film by the heat processing temperature change is demonstrated. In this heat treatment test, the five types of alloy films (i) to (m) described above were used as samples, and heat treatment was performed at a heat treatment temperature of 500 ° C., 600 ° C., and 700 ° C. in a vacuum atmosphere. investigated. The results are shown in FIG. 13 ((i), (j), (k)) and FIG. 14 ((l), (m)).
図１３の（ｉ）４３．６ａｔ％Ｐｔ組成におけるＸＲＤ回折パターンでは、５００℃熱処理の構造は（α−Ｃｏ，Ｐｔ）固溶体で、その構造変化は見られなかった。６００℃熱処理では、３３°付近にわずかにＬ１０構造を示す回折ピークが現れ、規則化が始まったことが確認された。さらに、７００℃熱処理では、Ｌ１０構造を示す回折ピークが明らかに出現した。また、立方晶構造から正方晶構造への変化を示す（２００）及び（００２）回折ピークは***して現れたが、（３１１）及び（１１３）回折ピークの***は若干みられたものの、完全ではなかった。また、Ｌ１０構造以外を示す回折ピーク（２９．８°、４５．３°）が現れたが、同定不能だった。この結果から（ｉ）４３．６ａｔ％ＰｔのＣｏ−Ｐｔ合金膜では、Ｌ１０構造だけでなく第二相が存在する可能性が判明した。 In the XRD diffraction pattern in (i) 43.6 at% Pt composition of FIG. 13, the structure of the heat treatment at 500 ° C. was an (α-Co, Pt) solid solution, and the structural change was not observed. The 600 ° C. heat treatment, a diffraction peak showing slightly L1 0 structure around 33 ° appears, that the ordering began was confirmed. Furthermore, in the 700 ° C. heat treatment, a diffraction peak indicating an L1 0 structure was clearly emerged. In addition, although the (200) and (002) diffraction peaks indicating the change from the cubic structure to the tetragonal structure appeared to be split, the splitting of the (311) and (113) diffraction peaks was slightly observed, but the complete It wasn't. Also, L1 0 diffraction peaks indicating none structure (29.8 °, 45.3 °) but appeared was impossible identified. In the Co-Pt alloy film results from (i) 43.6at% Pt, possibly second phase not only L1 0 structure is present is known.
次に、図１３の（ｊ）４４．９ａｔ％Ｐｔ組成におけるＸＲＤ回折パターンでは、（ｉ）の場合と同様に、５００℃熱処理では（α−Ｃｏ，Ｐｔ）固溶体のままで、その構造変化は見られなかった。しかし、６００℃熱処理を行うと、規則化を示す超格子の回折ピークが３３°や６１°付近に現れはじめ、７００℃熱処理でＬ１０構造を示す回折ピークのみとなった。また、７００℃熱処理では、（２００）と（００２）回折ピークや、（３１１）と（１１３）の回折ピークが完全に***し、立方晶から正方晶に構造変化をしていることが判った。 Next, in (j) XRD diffraction pattern of 44.9 at% Pt composition in FIG. 13, as in the case of (i), the (α-Co, Pt) solid solution remains in the 500 ° C. heat treatment, and its structural change is I couldn't see it. However, when the 600 ° C. heat treatment begin to appear in the vicinity of the diffraction peak of the superlattice 33 ° and 61 ° indicating the ordering and became only the diffraction peak showing an L1 0 structure 700 ° C. heat treatment. In addition, it was found that the (200) and (002) diffraction peaks and the (311) and (113) diffraction peaks were completely split in the heat treatment at 700 ° C., and the structure changed from cubic to tetragonal. .
図１３の（ｋ）、図１４の（ｌ）、（ｍ）のＣｏ−Ｐｔ合金膜では、（ｊ）の場合と同様な結果が得られた。また、膜の組成が５０ａｔ％に近づくにつれて、６００℃熱処理した試料は、３３°や６１°の回折ピークのほかに２４°、５４°付近にもＬ１０構造を示す回折ピークが強く現れるようになった。 In the case of the Co—Pt alloy films of (k) in FIG. 13, (l) and (m) in FIG. 14, the same result as in the case of (j) was obtained. Further, as the composition of the membrane approaches 50at%, 600 ° C. heat-treated samples, in addition to 24 ° of the diffraction peak of 33 ° or 61 °, as diffraction peaks indicating also L1 0 structure around 54 ° appears strongly became.
続いて、上記したＸＲＤの回折ピークから、熱処理温度における格子定数（ａ軸及びｃ軸）の変化を調査した。その結果を図１５に示す。図１５を見ると判るように、５００℃熱処理では総ての組成の合金膜において、ａ軸とｃ軸の格子定数は一致しており、立方晶構造であることが確認されたが、６００℃熱処理になるとａ軸の格子定数は増大し、ｃ軸の格子定数は減少し始め、７００℃熱処理になるとさらにその差は大きくなり、正方晶構造に変化したことが確認された。ＪＣＰＤＳカード（ＰＯＷＤＥＲ ＤＩＦＦＲＡＣＴＩＯＮ ＦＩＬＥ ＳＥＴ４３ ＩＮＯＲＧＡＮＩＣ ａｎｄ ＯＲＧＡＮＩＣ ＤＡＴＡ ＢＯＯＫ）から算出したＬ１０型ＣｏＰｔ合金膜はｃ／ａの値は約０．９７であることから、本実施形態での電析Ｃｏ−Ｐｔ合金膜は７００℃熱処理でほぼ完全にＬ１０構造に変化することが判明した。 Subsequently, changes in lattice constants (a-axis and c-axis) at the heat treatment temperature were investigated from the above-mentioned XRD diffraction peaks. The result is shown in FIG. As can be seen from FIG. 15, in the alloy film of all compositions in the 500 ° C. heat treatment, the lattice constants of the a axis and the c axis coincide with each other, and it was confirmed that it has a cubic structure. With heat treatment, the a-axis lattice constant increased and the c-axis lattice constant began to decrease. With 700 ° C. heat treatment, the difference further increased, confirming a change to a tetragonal structure. Since JCPDS card (POWDER DIFFRACTION FILE SET43 INORGANIC and ORGANIC DATA BOOK) L1 0 type CoPt alloy film calculated from the value of c / a is about 0.97, electrodeposition CoPt alloy film in this embodiment It was found to vary almost completely L1 0 structure 700 ° C. heat treatment.
次に、（ｊ）４４．９ａｔ％Ｐｔ組成の電析Ｃｏ−Ｐｔ合金膜について、各熱処理後の構造解析（格子像、電子線回折図形）をＨＲＴＥＭにより行った（図１６）。図１６に示す格子像から、熱処理前のａｓ−ｄｅｐｏｓｉｔｅｄの膜では、結晶粒径は約５ｎｍ程度で、はっきりした粒界が確認された。しかし、５００℃熱処理では、その粒界が明確でなくなった。さらに６００℃熱処理になると、５００℃熱処理では観察されなかったｃ軸によるものと考えられる格子縞のはっきりした丸い粒子が現れ始め、７００℃熱処理では様々な場所でこの丸い粒子が観察された。この丸い粒子の粒径は２〜３ｎｍであった。また、電子線回折図形からその構造を解析したところ、ａｓ−ｄｅｐｏｓｉｔｅｄの膜では（α−Ｃｏ，Ｐｔ）固溶体の回折環や回折斑点が現れ、５００℃熱処理でも同様であった。しかし６００℃熱処理では（１１１）よりも内側に回折斑点が現れており、これを解析したところ、Ｌ１０構造を示す（００１）と（１１０）の回折斑点であり、Ｌ１０構造が明らかに出現していることが確認された。そして７００℃熱処理では、Ｌ１０構造を示す回折斑点のみが現れていることが判った。 Next, for the electrodeposited Co—Pt alloy film having the composition (j) 44.9 at% Pt, structural analysis (lattice image, electron diffraction pattern) after each heat treatment was performed by HRTEM (FIG. 16). From the lattice image shown in FIG. 16, in the as-deposited film before the heat treatment, the crystal grain size was about 5 nm, and a clear grain boundary was confirmed. However, the grain boundary became unclear in the 500 ° C. heat treatment. Further, when the heat treatment was performed at 600 ° C., round particles with clear lattice fringes considered to be due to the c-axis, which were not observed in the heat treatment at 500 ° C., started to appear. The diameter of the round particles was 2 to 3 nm. Moreover, when the structure was analyzed from the electron diffraction pattern, a diffraction ring and diffraction spots of (α-Co, Pt) solid solution appeared in the as-deposited film, which was the same even at 500 ° C. heat treatment. However, at 600 ° C. heat treatment has appeared inside diffraction spots than (111), was analyzed with this, a diffraction spots showing the L1 0 structure (001) and (110), L1 0 structure clearly emerged It was confirmed that And in 700 ° C. heat treatment, it was found that only the diffraction spots showing the L1 0 structure has appeared.
さらに、本実施形態の各電析Ｃｏ−Ｐｔ合金膜について、磁気ヒステリシス曲線を測定して、その保磁力と熱処理温度との関係を調べた結果を説明する。この磁気ヒステリシス曲線の測定は、第一実施形態の場合と同様である。図１７には、（ｉ）〜（ｍ）の５種類の合金膜についてその保磁力を測定し、熱処理温度との関係を調べたものである。図１７に示すように（ｉ）の合金膜では、熱処理を行っていないａｓ−ｄｅｐｏｓｉｔｅｄ及び５００℃熱処理の膜では、保磁力は非常に値が小さく、熱処理温度に伴う保磁力の変化も見られなかった。６００℃以上の熱処理になると、保磁力が若干増加したが、急激な増大ではなかった。これは、図１３の（ｉ）でついて説明したように、７００℃熱処理でＬ１０構造及びＬ１０構造以外の第２相の存在によるものであると考えられた。 Furthermore, the result of having measured the magnetic hysteresis curve about each electrodeposition Co-Pt alloy film of this embodiment and investigated the relationship between the coercive force and the heat processing temperature is demonstrated. The measurement of the magnetic hysteresis curve is the same as in the first embodiment. FIG. 17 shows the relationship between the coercive force of five types of alloy films (i) to (m) and the heat treatment temperature. As shown in FIG. 17, in the alloy film of (i), the coercive force is very small in the as-deposited and 500 ° C. heat-treated films that are not heat-treated, and the coercive force changes with the heat treatment temperature. There wasn't. When the heat treatment was performed at 600 ° C. or higher, the coercive force slightly increased, but not a rapid increase. This was considered to be due to the presence of the L1 0 structure and the second phase other than the L1 0 structure in the 700 ° C. heat treatment, as described with reference to FIG.
図１７で示した（ｊ）合金膜の結果では、ａｓ−ｄｉｐｏｓｉｔｅｄでは保磁力が非常に小さな値であったが、熱処理温度の上昇に伴って保磁力は増大する傾向を示し、Ｌ１０構造が現れ始める６００℃以上で保磁力値は急激に増加し、７００℃熱処理では保磁力Ｈｃ＝５．９ｋＯｅという大きな値を示した。また、（ｋ）〜（ｍ）の合金膜について、その保磁力は（ｊ）と同様な傾向であった。しかし、７００℃熱処理における最も高い保磁力は、Ｃｏ−Ｐｔ合金膜組成によりその値は大きく異なった。基本的には。５０ａｔ％Ｐｔ組成に近いほど高い保磁力を示し、本実施形態の中で最も高いものは（ｍ）５１．８ａｔ％Ｐｔ組成のＣｏ−Ｐｔ合金膜で、保磁力Ｈｃ＝８．２ｋＯｅであった。 The result of (j) alloy film shown in FIG. 17, although the coercive force in the as-diposited was very small value, a tendency that the coercive force increases with increasing heat treatment temperature, the L1 0 structure The coercive force value increased abruptly at 600 ° C. or higher when it began to appear, and a large value of coercive force Hc = 5.9 kOe was shown by heat treatment at 700 ° C. Further, the coercive force of the alloy films (k) to (m) had the same tendency as (j). However, the highest coercive force in 700 ° C. heat treatment varies greatly depending on the Co—Pt alloy film composition. Basically. The closer to 50 at% Pt composition, the higher the coercive force, and the highest in this embodiment is (m) 51.8 at% Pt composition Co—Pt alloy film with coercive force Hc = 8.2 kOe. .
図１３〜図１６の結果より、５０ａｔ％Ｐｔ組成のＣｏ−Ｐｔ合金膜は、６００℃以上の熱処理で、超格子を示す規則化が開始し、７００℃熱処理でＬ１０構造に変化し、その構造変化に伴って保磁力も増大することが判った。そこで、７００℃熱処理における（ｉ）〜（ｍ）組成の各Ｃｏ−Ｐｔ合金膜において、その構造や格子定数に相違があるかを調べた。図１８には、７００℃熱処理におけるＸＲＤ回折パターンを示す。図１８を見ると判るように、いずれの組成においても７００℃熱処理で総てＬ１０構造に変化していたことが確認できた。しかし、完全にＬ１０構造となっている膜であっても、膜中のＰｔ濃度の増加に伴い（２００）と（００２）の回折ピークなどのＬ１０構造を示す回折ピークは低角度側にシフトする傾向が見られた。 From the results of FIGS. 13 to 16, Co-Pt alloy film 50at% Pt composition, heat treatment at above 600 ° C., to begin the ordering indicating the superlattice varies in L1 0 structure 700 ° C. heat treatment, the It was found that the coercive force increases with the structural change. Therefore, it was examined whether each Co—Pt alloy film having the compositions (i) to (m) in 700 ° C. heat treatment has a difference in structure or lattice constant. In FIG. 18, the XRD diffraction pattern in 700 degreeC heat processing is shown. As can be seen from FIG. 18, it was confirmed that was changed to all L1 0 structure 700 ° C. heat treatment in any of the composition. However, even with a film having a completely L1 0 structure, the diffraction peaks showing the L1 0 structure, such as the diffraction peaks of (200) and (002), on the lower angle side as the Pt concentration in the film increases. There was a tendency to shift.
そこで、図１８に示す回折ピークから格子定数を算出し、膜中のＰｔ濃度と格子定数との関係を調べた。図１９にその結果を示す。図１９を見ると判るように、７００℃熱処理では、各組成においてｃ／ａ値は０．９７であることから総てＬ１０構造に変化していたことが確認された。また、Ｐｔ濃度の増加に伴って、ａ軸、ｃ軸ともに格子定数の増加する傾向が認められた。 Therefore, the lattice constant was calculated from the diffraction peak shown in FIG. 18, and the relationship between the Pt concentration in the film and the lattice constant was examined. FIG. 19 shows the result. As it can be seen from Figure 19, the 700 ° C. heat treatment, c / a value in each composition was confirmed that was changed to all L1 0 structure because it is 0.97. Further, as the Pt concentration increased, the lattice constant tended to increase for both the a-axis and the c-axis.
最後に、本実施形態の電析Ｃｏ−Ｐｔ合金膜の７００℃熱処理における保磁力とＰｔ濃度との関係について調べた結果について説明する。図２０に、（ｉ）〜（ｍ）組成の各Ｃｏ−Ｐｔ合金膜における７００℃熱処理の保磁力とそのＰｔ濃度との関係を示す。図２０より、７００℃熱処理における保磁力は、Ｐｔ濃度の増加に伴って明らかに増加する傾向を示し、５０ａｔ％Ｐｔ組成に近づくほど高い保磁力を示すことか判明した。最も高い保磁力は、（ｍ）５１．８ａｔ％Ｐｔ組成で７００℃熱処理によった場合で、保磁力Ｈｃ＝８．２ｋＯｅであった。この値は、現在用いられている磁気記録メディアの保磁力Ｈｃ＝１ｋＯｅ〜５ｋＯｅよりも大きく、優れた磁気特性を示すものであった。 Finally, the results of examining the relationship between the coercive force and the Pt concentration in the 700 ° C. heat treatment of the electrodeposited Co—Pt alloy film of this embodiment will be described. FIG. 20 shows the relationship between the coercive force of 700 ° C. heat treatment and the Pt concentration in each Co—Pt alloy film having the compositions (i) to (m). From FIG. 20, it was found that the coercive force in the heat treatment at 700 ° C. clearly shows a tendency to increase as the Pt concentration increases, and that the coercive force becomes higher as the composition approaches 50 at% Pt. The highest coercive force was (m) 51.8 at% Pt composition subjected to heat treatment at 700 ° C., and the coercive force Hc = 8.2 kOe. This value was larger than the coercive force Hc = 1 kOe to 5 kOe of the magnetic recording media currently used, and exhibited excellent magnetic properties.
以上の結果より、本実施形態における電析Ｃｏ−Ｐｔ合金膜の構造とその磁気特性は次のような特徴的な関係があると考えられた。ＸＲＤの構造分析及び格子定数の結果より、Ｃｏ：Ｐｔの原子組成比が厳密に１：１でない場合は多い元素が少ない元素の存在しているべき位置に置換されていることが考えられ、その結果、完全な積層構造が保てなくなり、磁気異方性が弱まり、５０ａｔ％Ｐｔ組成から離れていく組成になるほど、保磁力が減少することになるものと推測された。 From the above results, it was considered that the structure of the electrodeposited Co—Pt alloy film in the present embodiment and its magnetic characteristics have the following characteristic relationship. From the results of structural analysis and lattice constant of XRD, it is considered that when the atomic composition ratio of Co: Pt is not strictly 1: 1, a large amount of elements are substituted at positions where a small number of elements should exist. As a result, it was speculated that the coercive force would decrease as the composition could not be maintained, the magnetic anisotropy was weakened, and the composition deviated from the 50 at% Pt composition.
Claims (4)
塩化コバルト六水和物を０．５〜２０ｇ／Ｌと、塩化白金酸（ＩＶ）を２〜６０ｇ／Ｌと、酒石酸アンモニウムを０．５〜５０ｇ／Ｌとを含有するコバルト−白金合金電析めっき浴を用いて電析コバルト−白金合金膜を形成し、
該電析コバルト−白金合金膜を２００℃〜８００℃において熱処理を行うことを特徴とするコバルト−白金合金磁性膜の製造方法。 A method for producing a cobalt-platinum alloy magnetic film,
Cobalt-platinum alloy electrodeposition containing 0.5 to 20 g / L of cobalt chloride hexahydrate, 2 to 60 g / L of chloroplatinic acid (IV), and 0.5 to 50 g / L of ammonium tartrate. Using a plating bath to form an electrodeposited cobalt-platinum alloy film,
A method for producing a cobalt-platinum alloy magnetic film, comprising heat-treating the electrodeposited cobalt-platinum alloy film at 200 ° C to 800 ° C.
真空雰囲気中、２００℃〜８００℃の温度範囲にて熱処理を行う請求項１〜請求項３に記載のコバルト−白金合金磁性膜の製造方法。
Cobalt chloride hexahydrate and chloroplatinic acid (IV) were used in a cobalt-platinum alloy electrodeposition plating bath in which cobalt: platinum was 7: 3 to 1: 9,
The method for producing a cobalt-platinum alloy magnetic film according to claim 1, wherein the heat treatment is performed in a temperature range of 200 ° C. to 800 ° C. in a vacuum atmosphere.
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| JP2005048232A (en) * | 2003-07-28 | 2005-02-24 | Electroplating Eng Of Japan Co | Method of producing cobalt-platinum alloy magnetic film by using electrodeposition process |
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| JPH10212592A (en) * | 1997-01-28 | 1998-08-11 | Tanaka Kikinzoku Kogyo Kk | Platinum alloy plating bath |
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