DE4226914A1 - Magnetic recording support with improved recording properties - comprises ferromagnetic layer formed on polymer support treated by ion beam and sputter etching - Google Patents

Abstract

Magnetic recording support comprises a polymer support material, whose main surface is plasma-treated, and a 10-1000 nm thick, ferromagnetic layer formed on the support material. The novelty is that main surface of the support material is treated by ion beam and sputter etching. Pref. the ferromagnetic layer consists of Co and Cr. Ion beam etching uses O2 ions and sputter etching uses Ar. ADVANTAGE - Improved recording properties.

Description

The invention relates to magnetic recording media, be standing from a flat, polymeric carrier material, the at least one major surface is plasma treated, and egg ner on this plasma-treated main surface of the carrier mat rials formed ferromagnetic layer.

Magnetic recording media, their magnetic layer from a coherent, ferromagnetic metal thin layer are known. Compared to the ge used particulate magnetic media allow thin-film media higher storage densities. This increase in information density for a given storage area results from both the smaller layer thickness of the thin metal layers and the associated low demagnetization effect than also from the higher number of available Ele ment magnets per unit volume. Another increase the storage density is due to the transition from the longitu dinal- for inclined or vertical recording possible, so that in particular magnetic recording media with oblique Preferred direction of magnetization or of the vertical type experience significant interest.

The usual Ver. In the production of thin film media driving the application of the ferromagnetic metal layer through the PVD methods of sputtering, ion plating or Vapor deposition must be done by selecting the process parameters be designed so that the magnetic layer with the desired Morphology and crystallographic orientation grows up. The carrier mat also has a significant influence here rial. The related, often contradicting ones Effects make the coordination difficult in detail. For example, for cobalt / chrome alloy layers for the vertical recording ent the desired layer growth neither by sub-layers, for example made of Si, Ge or Ti (O. Kitakami et al., IEEE Trans. Magn. 25 (3), 2607 (1989)) or by means of suitable substrate pretreatments such as Ion beam etching (R. Sugita et al., IEEE Trans. Magn. 26 (5), 2286 (1990)). In addition, the substrate is  temperature during coating typically between 150 and 250 ° C (R. Sugita et al .: IEEE Trans. Magn. 26 (5), 2286 (1990), M. Futamoto: Digest Intermag 90, Pa by BP-16 (1990)). For this reason, the manufacturer development of such layers of temperature-stable substrate materials be used. The deformation or decomposition may occur of the carrier material under the influence of heat during the Layer formation through the use of heat-resistant Polymers, such as polyamides and polyimides, as carriers for Inclusion of the metal suitable for vertical recording layers are avoided, but the disadvantage is that the most heat-resistant polymers are very expensive.

The object of the invention is a magnetic recording Mungträger, in which the magnetic layer on a plasma acted carrier film is applied, ready to provide does not have the disadvantages mentioned and the improved Shows recording properties.

It has now been found that a magnetic record Mung carrier consisting of a flat polymeric carrier material whose at least one major surface is in a atmosphere containing inorganic gas is plasma-treated and one on the treated major surface of the carrier terials trained, 10 to 1000 nm thick, ferromagneti layer fulfills the given task if at least the main surface provided for the ferromagnetic layer of the carrier material with two different plasma processes from the group of ion beam etching and sputter etching is.

In an advantageous embodiment of the invention The magnetic recording medium is the polymeric carrier material one that is first used by ion beam etching Oxygen ions and then sputter etched with argon delt was.

In ion beam etching, electrons emerging from a heated cathode are accelerated by electrical and magnetic fields. On their way to the anode, they ionize particles of an admitted gas, e.g. B. Ar, O ₂ , N ₂ . The positively charged gas ions and part of the electrons (charge neutralization) are accelerated onto the film. Typical ion energies are between 10 and 2000 eV. In sputter etching, on the other hand, in the space between the foil and an electrode opposite this, by applying an electrical voltage to the substrate carrying element (e.g. 13.56 MHz, 100-1000 W power) with gas inlet (e.g. Ar, O ₂ , N ₂ ) ignited a plasma. As long as the plasma is on, the film is bombarded with ions, electrons and photons.

Ion etching and sputter etching cause cleaning Outgassing and a change in chemical composition and the topography of the film surface.

In the manufacture of the magnetic up according to the invention A polymer substrate is used as the carrier material for the drawing in particular from the group PET, PEN, polysulfone, PI, PA or PEEK selected. At least one major area of this The carrier material is then removed using two plasma processes the group of ion beam etching and sputter etching deals where in the sequence of ion beam etching and then sputtering Zen is preferred. The advantageously used In the case of ion beam etching, gases are oxygen and Sputter etching argon.

On a carrier material pretreated in this way is now with the known PVD techniques a ferromagnetic Layer, e.g. B. applied a cobalt / chrome layer. In be The cobalt / chrome layer can be of special configurations addition of elements from the group Ni, Ta, Zn, Nb, Hf, W, C, P, B, V, Mo, Fe, Pt, Y, La, Ce, Nd, Pr, Gd, Sm, Tb, Dy, Ho, Er, Yb, Ag, Zr included.

An advantage here is that vorbe as described traded carrier material in particular one for the vertical magnetization suitable magnetic layer even at low Substrate temperatures, i. H. between -20 and 100 ° C, up can be brought. The result of this procedure Magnetic layers have excellent recording properties on.  

The invention is illustrated below using examples of Ko balt / chrome layers and several comparative tests closer explained.

example 1

A 50 μm thick PI carrier film was first etched by ion beam with 0 ions: energy of the ions = 60 eV
Power density on the film surface = 0.17 W / cm ²
Treatment time = 5 min
and then through
Sputter etching with Ar: RF = 13.56 MHz
Sputter gas pressure = 5 · 10 ^-3 mbar
Power density on the film surface = 0.5 W / cm ²
Treatment time = 10 min
treated in situ in a conventional vaporization system.

A Co ₇₆ Cr ₂₄ layer with a thickness of 300 nm was then applied to this film in the vapor deposition system at a pressure of 1 × 10 ^-6 -1 × 10 ^-5 mbar by simultaneous two-source evaporation, the substrate material being at room temperature was held. A 20 nm thick C wear protection layer was then sputtered onto the Co ₇₆ Cr ₂₄ layer.

The magnetic properties of the resulting magnet layer are shown in Table 1.

Designate it
M _{s is} the saturation magnetization
m _r the relative remanence in the layer plane
H _{c, x} the coercive force in the layer plane
H _{c, z is} the coercive force perpendicular to the layer plane and
H _{k is} the anisotropy field strength (determined according to K. Ouchi, S. Iwasaki: IEEE Trans. Magn. 23 (5), 2443 (1987)).

The recording properties of the layer are shown in Fig. 1, curve (a) (normalized reading level U in nV / µm _* turn _* m / s against the recording density D in kfci). They were measured with a standard video ring head with a gap width of 0.23 µm, a track width of 27 µm and a number of turns of 18 at a head / medium relative speed of 1.2 m / s. The data points shown are corrected for the so-called "gap losses".

Example 2

The procedure was as described in Example 1, but a 50 μm thick PET carrier film was used, to which a Co ₇₄ Cr ₂₆ layer with a thickness of 300 nm was applied. The magnetic properties of the layer are given in Table 2. The recording properties of the magnetic data carrier are shown in Fig. 2, curve (a). They were measured under the same conditions as described in Example 1.

Comparative experiment 1

The procedure was as described in Example 1, but without plasma pretreatment of the PI film. The magnetic properties of the Co ₇₆ Cr ₂₄ layer applied are given in Table 1. The recording properties of the layer are shown in Fig. 1, curve (b). Compared to the course of this curve (b), the layer according to Example 1 (curve (a)) shows significantly better recording properties. This can be quantified by the values given in Table 3. In the table, D ₅₀ denotes the storage density in kfci (kilo flux changes per inch), at which the reading level is half of the maximum measured level in the curve (measured from the electronic noise marked by a dashed line).

Comparative experiment 2

The procedure was as described in Example 1, but the PI carrier film was only ion-etched with O ₂ . The magnetic properties of the Co ₇₆ Cr ₂₄ layer subsequently applied are given in Table 1. The recording properties of the layer are shown in Fig. 1, curve (c). This curve is also significantly worse at high recording densities than that of Example 1 (curve (a)). Again, this can be quantified by the values given in Table 3.

Comparative experiment 3

The procedure was as described in Example 1, but the PI carrier film was only sputter-etched with Ar. The magnetic properties of the Co ₇₆ Cr ₂₄ layer subsequently applied are given in Table 1. The recording properties of the layer are shown in Fig. 1, curve (d). The curve is again worse than that of Example 1 (curve (a)). This is quantified by the values given in Table 3.

Comparative experiment 4

The procedure was as described in Example 2, but the PET carrier film was only ion-etched with O₂. The magnetic properties of the Co ₇₄ Cr ₂₆ layer subsequently applied are given in Table 2. The recording properties of the layer are shown in Fig. 2, curve (b). The curve is significantly worse than that of Example 2 (curve (a)). This can be quantified by the values given in Table 4.

Comparative experiment 5

The procedure was as described in Example 2, but the PET carrier film was only sputter-etched with Ar. The magnetic properties of the Co ₇₄ Cr ₂₆ layer subsequently applied are given in Table 2. The recording properties of the layer are shown in Fig. 2, curve (c). The curve is again significantly worse than that of Example 2 (curve (a)), which can be quantified by the values given in Table 4.

Table 1

Table 2

Table 3

Table 4

Claims (4)

1. Magnetic recording medium, consisting of a flat polymeric carrier material, the at least one main surface of which is plasma-treated, and a form on the treated main surface of the carrier material, 10 to 1000 nm thick, ferromagnetic layer, characterized in that at least that for the ferromagnetic layer intended main surface of the carrier material is treated with at least two different plasma processes from the group of ion beam etching and sputtering. 2. Magnetic recording medium according to claim 1, there characterized in that the ferromagnetic layer consists essentially of cobalt and chrome. 3. Magnetic recording medium according to claim 1 or 2, characterized in that the carrier material first by ion beam etching and then by sputtering zen is treated. 4. Magnetic recording medium according to claim 1 or 2, characterized in that the carrier material first by ion beam etching with oxygen ions and then is treated by sputter etching with argon.