【発明の詳細な説明】[Detailed description of the invention]
〔産業上の利用分野〕
本発明は、鉄を主材料とした薄膜型磁気記録媒
体の製造方法に関する。
〔従来の技術〕
薄膜型磁気記録媒体は高密度磁気記録媒体とし
て実用化が図られつゝある。
本件発明者らは、特開昭60−231924号公報で開
示されたように、磁性膜を形成する磁性体として
コバルトを用いた薄膜型高密度磁気記録媒体に代
わり、磁性体として鉄系化合物を用いた薄膜型磁
気記録媒体の製造方法を提案した。
この薄膜型高密度磁気記録媒体は、鉄または鉄
合金等の強磁性体の蒸気を、窒素と酸素を含む混
合ガスのイオンと共に非磁性の基材の上に照射す
ることにより、基材上に磁性膜を成膜して作られ
る。この方法で成膜された磁性膜の磁気特性は、
上記混合ガスの酸素濃度が約20％、入射角が基材
の法線に対して80°のときが最も良く、保磁力が
16000e、角型比が0.9以上である。
〔発明が解決しようとする問題点〕
しかし、より高い出力を有する高密度磁気記録
媒体として、従来よりさらに高い保磁力を有する
磁性膜が要望されていたが、上記の保磁力を越え
るものは未だ得られていない。
本発明は、このような問題を解消するためなさ
れたもので、その目的は、より高い保磁力の磁性
膜を持つた薄膜型磁気記録媒体が製造できる方法
を提供することにある。
〔問題を解決するための手段〕
この発明による薄膜型磁気記録媒体の製造方法
は、基材上に鉄の蒸気を入射させると共に、窒素
と酸素を含む混合ガスの励起された分子（以下
「励起種」という。）を上記基材上に照射するもの
である。
〔作用〕
上記励起種（excited species）とは、量子力
学系の定常状態のうち、基底状態より高いエネル
ギー準位にある電気的に中性な分子をいい、励起
分子ともいわれる。この励起分子は、基底状態の
分子間では起こらないような反応が起こるとされ
ており、これを鉄分子、つまり鉄の蒸気と共に基
材上に入射させると、その表面に鉄系化合物から
なる磁性膜が成膜される。後述する如く、この磁
性膜の磁気特性は、前述した従来技術の方法によ
り製造された磁気記録媒体の磁性膜の特性に比
べ、特に保持力がはるかに優れている。
〔実施例〕
次に図面を参照しながら、本発明の実施例につ
いて説明する。
図面は、本考案による発明を実施するための装
置の例である。鉄の分子、つまり鉄の蒸気は、蒸
発源１である鉄に電子銃５から電子を照射し、そ
の衝撃によつて発生させ、これを基材１に入射さ
せる。
他方、上記鉄分子と共に基材１に入射させる準
安定状態にある励起種は、例えば図面において６
で示すような励起種発生装置で作られ、基材２の
上に照射される。即ち、バルブ４側から混合ガス
を反応管３の中に導入し、フイラメント８を加熱
して、反応管３内に熱電子を放出させると共に、
上記反応管３とグリツト７にプラス数＋ボルトの
電圧を印加することにより、上記励起種が発生
し、これが基材２に照射される。
上記混合ガス中に含まれる酸素ガスの濃度は、
10〜30％の範囲が適当であり、特に20％前後の濃
度で最も良好な結果が得られる。混合ガスの酸素
ガスの濃度がこれより低くなると、磁性膜の角型
比が悪くなり、また逆に酸素ガスの濃度が高くな
ると磁性が低下し、約50％程で蒸着膜がほゞ非磁
性となる。
次に、この発明のより具体的な実施例を、得ら
れた測定結果の数値と共に説明する。
図面で示すような装置において、蒸発源１とし
て純度99.9％の鉄を、非磁性の基材２として35mm
角のガラス製基板を用い、この上に次の方法で磁
性膜を形成した。
真空槽内の気圧を10-6Torr以下の真空状態と
し、電子銃５から上記蒸発源１に電子線を照射し
て、同蒸発源１を蒸発させ、これから発生した鉄
の蒸気を80°の入射角で基板２の上に照射した。
またこれと同時に、バルブ４を介して励起種発
生装置６の反応管３に窒素ガスと酸素ガスを含む
混合ガスを導入し、これを励起して基板２の上に
照射した。このとき、励起種発生装置６の熱電子
放出用タングステンフイラメント８の電圧を8V、
電流を16A、反応管３とグリツド７の電圧を50V
とし、真空槽内の真空度を１×10-4Torr、混合
ガス導入量を１〜2scc／minとした。
蒸発源１からの蒸発速度は、基板２に隣接し、
かつこれと同じ高さに設置したセンサで測定しな
がら、これと連動させた水晶振動式膜厚計
（XTM）の指示値が20Å／secになるように制御
した。
混合ガスについては、酸素ガスの濃度を０、
５、10、20、30、50％と６段階に分けて実施し
た。なお、これら混合ガスの残部は、殆どが窒素
ガスである。
次に、こうして形成された磁気記録媒体につい
てそれぞれ試料振動型磁力計によつて磁性膜のＭ
−Ｈ特性を測定し、保磁力と角型比を求め、さら
に触針式膜厚計によつて磁性膜の膜厚を測定し
た。この結果を表１に示す。なお磁性膜の膜厚
は、何れの磁気記録媒体も1000〜1500Å程度であ
つた。
また、これらの磁気記録媒体を濃度５％の食塩
水に３ケ月間浸漬した後取り出し、磁性膜の外観
及び磁気特性を調べたところ、浸漬前と比べて変
化は見られなかつた。
表１の結果から明らかなように、上記混合ガス
の酸素ガス濃度を10％としたときの磁性膜は、鉄
の蒸気と共に酸素濃度20％の混合ガスのイオンを
入射して成膜した従来の磁性膜とほぼ同等の磁気
特性が得られた。さらに、酸素濃度を20％とした
ときは、それ以上の磁気特性が得られた。
[Industrial Application Field] The present invention relates to a method for manufacturing a thin film magnetic recording medium mainly made of iron. [Prior Art] Thin-film magnetic recording media are being put into practical use as high-density magnetic recording media. As disclosed in Japanese Patent Application Laid-Open No. 60-231924, the inventors of the present invention have developed an iron-based compound as a magnetic material instead of a thin film type high-density magnetic recording medium that uses cobalt as a magnetic material forming a magnetic film. We proposed a manufacturing method for thin-film magnetic recording media. This thin-film high-density magnetic recording medium is produced by irradiating vapor of a ferromagnetic material such as iron or iron alloy onto a non-magnetic substrate along with ions of a mixed gas containing nitrogen and oxygen. It is made by depositing a magnetic film. The magnetic properties of the magnetic film formed by this method are as follows:
It is best when the oxygen concentration of the above mixed gas is approximately 20% and the incident angle is 80° to the normal to the substrate, and the coercive force is
16000e, squareness ratio is 0.9 or more. [Problems to be solved by the invention] However, as a high-density magnetic recording medium with higher output, there has been a demand for a magnetic film with an even higher coercive force than before, but there is still no one that exceeds the above coercive force. Not obtained. The present invention was made to solve these problems, and its purpose is to provide a method for manufacturing a thin film magnetic recording medium having a magnetic film with higher coercive force. [Means for Solving the Problems] A method for manufacturing a thin film magnetic recording medium according to the present invention involves injecting iron vapor onto a base material and injecting excited molecules (hereinafter referred to as "excited") of a mixed gas containing nitrogen and oxygen. (referred to as "seed") onto the above substrate. [Operation] The above-mentioned excited species refers to electrically neutral molecules that are at an energy level higher than the ground state in the steady state of a quantum mechanical system, and are also called excited molecules. These excited molecules are said to cause a reaction that does not occur between molecules in the ground state, and when these excited molecules are incident on a substrate together with iron molecules, that is, iron vapor, magnetic properties made of iron-based compounds appear on the surface. A film is deposited. As will be described later, the magnetic properties of this magnetic film are far superior, particularly in terms of coercive force, compared to the properties of the magnetic film of the magnetic recording medium manufactured by the method of the prior art described above. [Example] Next, an example of the present invention will be described with reference to the drawings. The drawings are examples of apparatus for carrying out the invention according to the invention. Iron molecules, that is, iron vapor, are generated by the impact of electrons irradiated onto iron, which is the evaporation source 1, from an electron gun 5, and are made to enter the base material 1. On the other hand, the excited species in a metastable state that is incident on the base material 1 together with the iron molecules is, for example, 6 in the drawing.
It is produced using an excited species generator as shown in , and is irradiated onto the base material 2 . That is, a mixed gas is introduced into the reaction tube 3 from the valve 4 side, the filament 8 is heated, and thermionic electrons are released into the reaction tube 3.
By applying a voltage of plus several volts to the reaction tube 3 and the grit 7, the excited species is generated, and the substrate 2 is irradiated with the excited species. The concentration of oxygen gas contained in the above mixed gas is
A range of 10 to 30% is suitable, and best results are obtained especially at a concentration of around 20%. If the concentration of oxygen gas in the mixed gas is lower than this, the squareness ratio of the magnetic film will deteriorate, and conversely, if the concentration of oxygen gas is higher, the magnetism will decrease, and at about 50%, the deposited film will become almost non-magnetic. becomes. Next, more specific examples of the present invention will be described together with numerical values of the obtained measurement results. In the apparatus shown in the drawing, 99.9% pure iron is used as the evaporation source 1, and 35 mm is used as the non-magnetic base material 2.
A square glass substrate was used, and a magnetic film was formed thereon by the following method. The pressure inside the vacuum chamber is set to a vacuum state of 10 -6 Torr or less, and the electron beam is irradiated from the electron gun 5 to the evaporation source 1 to evaporate the evaporation source 1, and the iron vapor generated from this is heated at 80°. irradiated onto the substrate 2 at an incident angle. At the same time, a mixed gas containing nitrogen gas and oxygen gas was introduced into the reaction tube 3 of the excited species generator 6 via the valve 4, and the mixed gas was excited and irradiated onto the substrate 2. At this time, the voltage of the thermionic emission tungsten filament 8 of the excited species generator 6 was set to 8V,
Current is 16A, voltage of reaction tube 3 and grid 7 is 50V.
The degree of vacuum in the vacuum chamber was 1×10 −4 Torr, and the amount of mixed gas introduced was 1 to 2 scc/min. The evaporation rate from the evaporation source 1 is adjacent to the substrate 2;
While measuring with a sensor installed at the same height, a quartz crystal film thickness meter (XTM) linked to this was controlled so that the indicated value was 20 Å/sec. For mixed gases, set the concentration of oxygen gas to 0,
It was conducted in six stages: 5, 10, 20, 30, and 50%. Note that the remainder of these mixed gases is mostly nitrogen gas. Next, for each of the magnetic recording media thus formed, the M of the magnetic film was measured using a sample vibrating magnetometer.
The -H characteristics were measured, the coercive force and squareness ratio were determined, and the thickness of the magnetic film was also measured using a stylus thickness meter. The results are shown in Table 1. The thickness of the magnetic film was approximately 1000 to 1500 Å in all magnetic recording media. Further, when these magnetic recording media were immersed in saline solution with a concentration of 5% for 3 months and then taken out and the appearance and magnetic properties of the magnetic films were examined, no changes were observed compared to before immersion. As is clear from the results in Table 1, when the oxygen gas concentration of the above mixed gas is 10%, the magnetic film formed by injecting iron vapor and ions of a mixed gas with an oxygen concentration of 20% is different from that of the conventional film formed by injecting iron vapor and ions of a mixed gas with an oxygen concentration of 20%. Magnetic properties almost equivalent to those of magnetic films were obtained. Furthermore, when the oxygen concentration was set to 20%, even higher magnetic properties were obtained.
〔発明の効果〕〔Effect of the invention〕
以上説明した通り、本発明によれば、従来の方
法により製造された鉄系化合物の磁性膜を有する
薄膜型磁気記録媒体に比べ、特に保磁力の高い磁
性膜を持つた薄膜型磁気記録媒体を提供できる効
果が得られる。
As explained above, according to the present invention, a thin film magnetic recording medium having a magnetic film having particularly high coercive force can be produced, compared to a thin film magnetic recording medium having a magnetic film made of an iron-based compound produced by a conventional method. You can get the effects that you can.
【図面の簡単な説明】[Brief explanation of the drawing]
図面は本発明を実施するための装置の一例を示
す概念図である。
１……蒸発源、２……基材、３……反応管、４
……バルブ、５……電子銃、６……励起種発生装
置、７……グリツド、８……フイラメント。
The drawing is a conceptual diagram showing an example of an apparatus for implementing the present invention. 1... Evaporation source, 2... Base material, 3... Reaction tube, 4
...Valve, 5...Electron gun, 6...Excited species generator, 7...Grid, 8...Filament.