JPS60229292A - Forming method of magnetic bubble transfer path - Google Patents

Abstract

PURPOSE:To form a magnetic bubble transfer path having a sufficiently large difference (DELTAHk) between anisotropic magnetic fields of non-implantation area and an implantation area and an excellent temperature characteristic by annealing a film at a prescribed temperature after implantation of ions. CONSTITUTION:When ions are implanted on a magnetic garnet single crystal film covered by an implantation mask pattern 1, a magnetic bubble transfer path consisting of an ion implantation drive area 2 and a non-implantation area 3 is formed. When said film i annealed at 600 deg.C or above, a positive growth induced magnetic anisotropy is suppressed, and Curie temperature returns to a value approximate to that immediately before the ion implantation, whereas the magnetic anisotropy will not return to its original. As a result the magnetic bubble transfer path can be obtained which has the large DELTAHk and satisfactory transfer and temperature characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for forming a transfer path for an ion implantation type S gas bubble element in which a transfer path for magnetic bubbles is provided by ion implantation.

(Prior art and interlayer points) In recent years, the development of ion-implanted magnetic bubble elements as solid-state file memories with high-density storage capacity has been progressing.

The characteristics required for the drive layer of an ion-implanted magnetic bubble element are that the uniaxial magnetic anisotropy constant value in the layer is negative so that the magnetization in the layer can be tilted in-plane, and the non-implanted region below the layer is negative. The difference ΔHk between the anisotropic magnetic field and the anisotropic magnetic field is sufficiently large.

Conventionally, in this element, ΔHk is obtained by the magnetostrictive effect from lattice distortion caused by ion implantation and selection C.

Conventionally, a typical bead-shaped mask pattern 1 for shielding implanted ions was formed on a magnetic garnet single crystal thin film grown on a non-magnetic garnet substrate as a yK magnetic bubble transfer path as shown in Fig. 1. By implanting ions from above, an ion-implanted layer 2 is formed, and a magnetic bubble transfer path along which magnetic bubbles are transferred along the outer boundary of the bead-shaped non-implanted region 3 is formed.

In this ion implantation process, as implanted ions.

Hydrogen, helium, and neon ions are mainly being considered, but in order to obtain a sufficiently large ΔHk, the implantation amount is 2 × 10 ”/cr/l to 4 × 1 in the case of hydrogen ions.
The implantation volume is 0"/cm, while when using neon ions, it ranges from 4 x 10 Is/crd to 5 x 10" 7m, 7i] x 10"/cm, respectively.
II') 2 X IQ" 775° is required.

In the case of hydrogen injection, manufacturing costs are high because the amount of injection is large.

In either case, the ion implantation process results in an ion implantation layer (
The Curie temperature of the drive layer (hereinafter referred to as the drive layer) decreases according to the amount of strain, and the higher the implantation amount, the greater the strain, and the greater the change in magnetic anisotropy, the greater the decrease in the Curie temperature. Therefore, if the amount of implantation required to cause a change in magnetic anisotropy for good device operation is performed, the temperature at 50°C
There was a problem in that the temperature decreased by about 100° C. and the temperature characteristics of the device deteriorated.

(Object of the Invention) The present invention has been made in view of the above points, and its object is to provide a method for forming a magnetic bubble transfer path having a sufficiently large ΔHk and good temperature characteristics.

(Structure of the Invention) That is, the present invention provides a method for forming a magnetic bubble transfer path by implanting ions onto a magnetic garnet single crystal thin film, after forming a mask for blocking the implanted ions on the magnetic garnet single crystal thin film. Inject and after this 60
This is a method for forming a magnetic bubble transfer path characterized by including a step of annealing at a temperature of 0° C. or higher.

(Summary of the present invention) In the present invention, in order to obtain the negative uniaxial anisotropy required for the drive layer in order to suppress the drop in the Curie temperature of the drive layer of the ion implantation type magnetic bubble element, the conventional This is achieved not only by the strain-induced magnetic anisotropy caused by ion implantation, but by partially suppressing the positive growth-induced magnetic anisotropy that the magnetic garnet film has.

That is, after forming a mask for forming a transfer path, ions are implanted in order to suppress positive growth-induced magnetic anisotropy, and then annealing is performed at a temperature of at least 600° C. By returning the lattice strain amount to 0% or a small amount, the Curie electric layer also returns to the Curie temperature before implantation or a temperature close to it. However, only the magnetic anisotropy does not return to its original state even after annealing, and the magnetic anisotropy constant value decreases. This is because the growth-induced magnetic anisotropy was suppressed as a result of the injection disturbing the lattice within the injection layer.

Since the degree of decrease in temperature due to strain caused by implantation is smaller than that of conventional traps, it is possible to improve the element temperature characteristics.

(Example) The present invention will be explained in more detail below with reference to Examples.

A magnetic garnet film (YSmLuCaBi)s (Pe
Ge) sOI! (Film thickness 1.2 μm, characteristic length 1 = 0
．． 12 ptn, saturated sir closed door 66nOuss
Mu JgnOn prcy /#J)~2.8X
IO) After forming a mask for the K171 stage 4 μm bead-shaped bubble transfer path with a 1 μW thick SIO using plasma CVD, neon ions were accelerated with an energy of 250 KeV.
)"-X amount 5.OX 10'nd and acceleration energy] 00KeV, dose amount 1.33 x 10"/cl
After injection, the magnetic bubble transfer path was formed by annealing in air at a temperature of 800° C. for 1 hour.

(Comparative Example) As a comparative example, a transfer path forming mask was formed using gold with a thickness of 5000X on a magnetic garnet film with the same characteristics as in the example, and then helium ions were accelerated at an energy of 100Ke.
V, dose amount 47 x 10''/all, and acceleration energy 40 KeV,)'' - dose amount 2.2 x
After implantation at 10''/d, a bubble transfer path was formed by annealing in air at 300° C. for 1 hour.

The magnetic bubble transfer characteristic of this example was 35,000e at room temperature, whereas the transfer characteristic of the comparative example having a transfer path formed by a known method for forming a magnetic bubble transfer path was 26,000e. Furthermore, the Curie temperature of the drive layer of the comparative example was 145.degree. C., whereas the Curie temperature of the drive layer of the example of the present invention was as high as 170.degree.

Although the annealing process after the neon implantation process was performed at a different temperature from that in the example, even at a low annealing temperature there was an effect of increasing ΔHk, which was greater than in the case of annealing at 800°C.

Although the key temperature is slightly lower, it is higher than that of the comparative example.

However, if the temperature was lower than 600° C., the crystallinity sometimes deteriorated. Even at temperatures above 1000°C, the effect of increasing ΔHk can be seen, and the key temperature was higher than that of the example.
Exceeds 80℃.

At 1050° C. or higher, the bubble film characteristics change, but in this case, there is no problem if the original bubble film is used, taking into account the change in the bubble film characteristics due to annealing.

In addition, the acceleration energy of this example is 25 oKeV and 10
Instead of the 0 KeV neon implantation step, ■ acceleration energy 200 KeV, dose 9 X 1014/d and acceleration energy 80 KeV, dose 3.8 XIO/d.
A step of implanting nitrogen ions of cI/l is performed to form a magnetic bubble transfer path.

Also, ■ acceleration energy 70KeV, dose amount, 1×10
/d and acceleration energy 35KeV, dose amount 4.5
A step of implanting hydrogen molecule ions of X10/d was performed to form a magnetic bubble transfer path.

In this way, even in the transfer path formation method in which the neon implantation process is replaced with nitrogen and hydrogen ion implantation, △Hk
A value comparable to that obtained with neon injection was obtained, and the decrease in Curie temperature was also comparable to that obtained with neon injection.

In this way, the effect is the same regardless of the ionic species, such as neon, hydrogen, nitrogen, helium, and holon.

(Effects of the Invention) As described above, the present invention makes it possible to provide a magnetic bubble transfer path with a high Curie temperature, good temperature characteristics, and a large k value, and good transfer characteristics. The place is very big.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the shape of a magnetic bubble transfer path. 1 Injection mask pattern 2 Ion implantation drive layer 3 Non-injection area Figure 71

Claims (1)

[Claims] In the method of forming a magnetic bubble transfer path by implanting ions onto a magnetic garnet single crystal thin film, a mask is formed on the magnetic garnet single crystal thin film to shield the implanted ions, and after the ion implantation, it is annealed at a temperature of 600°C or higher. A method for forming a magnetic bubble transfer path, comprising the step of: