JPS59217286A - Ion implantation magnetic bubble device - Google Patents

Abstract

PURPOSE:To reduce memory cell size and attain to high density by annealing some part between a transfer pattern through laser irradiation or diffusing externally an implanted ion by using a spacer mask, and decreasing an anisotropic magnetic field locally at said part between the transfer pattern. CONSTITUTION:Some part 8 between the transfer pattern 7 is irradiated with laser light and thus annealed to reduce magnetic strain, reducing an ion implanted anisotropic magnetic field (DELTAHk) at the irradiated part. Further, the spacer 10 made of silicon dioxide is provided covering the transfer pattern 7 and gap 9, and a window is formed at the part 8 of the gap 9 by etching; and a heat treatment is carried out to diffuse externally the implanted ions in an ion implanting layer 11 at the window part, reducing the DELTAHk of the ion implanting layer 11 at this part. Thus, part of the ion-implanted area between the transfer patterns is made into a small-DELTAHk area to reduce the mutual operation between the transfer patterns, and thus the malfunction of a bubble is prevented to reduce the memory cell size.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to the formation of an ion-implanted magnetic bubble device that reduces interaction between transfer paths and reduces memory cell size.Technical Background Magnetic Bubble Memory Devices (hereinafter referred to as bubble devices) include those that use the magnetization of a soft magnetic material to transfer magnetic bubbles (hereinafter referred to as bubbles), and those that utilize a thousand-yard wall that moves around the ion implantation region. The continuous pattern consisting of non-ion-implanted parts used in the latter device has a wider minimum limit dimension than the former, so it is suitable for forming transfer patterns for micro bubbles with a bubble diameter of 1 [μm]. The present invention relates to a magnetic film processing method for further improving the recording density in such an ion implantation device.

(at Prior Art and Problems Gurney) is a crystal that can be seen as a cubic system, and originally should not have magnetic anisotropy, but it contains at least two types of rare earth ions as its composition components. When at least one of the ions is a magnetic ion, magnetic anisotropy occurs due to spontaneous magnetization, and uniaxial magnetic anisotropy is observed in the direction perpendicular to the (100) plane of a single crystal. The (111) plane of a single crystal of gadolinium gallium garnet (GdRGasu, abbreviated as GGG), which is a non-magnetic garnet, is cut out, and magnetic garnet with the required composition is grown thereon by liquid phase epitaxial growth. In this way, a device is fabricated using a garnet film that has uniaxial magnetic anisotropy in the direction perpendicular to the substrate.The ion implantation device according to the present invention has a magnetic garnet film that is partially By performing ion implantation, the direction of magnetization, which is perpendicular to the film surface, is turned to parallel to the film surface, thereby forming a bubble transfer pattern. The present invention will be explained using the following drawings. Figure i1 shows the relationship between the connection pattern 1 used for bubble transfer in the ion implantation device I and the magnetic garnet film, (2) is a plan view, and t:pl is a cross-sectional view. The part including the adjacent pattern 1 indicated by diagonal lines in Fig. 1 is a magnetic layer epitaxially grown on GGG)
It is a film, and the direction of magnetization is perpendicular to the film surface. Here, the condition for stable spontaneous magnetization perpendicular to the film surface is that a uniaxial magnetic field Qk) exists perpendicular to the film surface, which is stronger than the demagnetizing field whose maximum value is 4π times the saturation magnetization. By Terukokichi.

In other words, UK>4πM8 However, the formation position of continuous pattern 1 is masked with a resist or vapor deposited film to generate hydrogen ions (H+) and neon ions (Ne+).
When ion implantation such as An induced anisotropic magnetic field Δ)IK is induced.

Ms t+r d However, λ・・・・・・Magnetostriction number E in the <111> direction
...... Young's modulus y ... Poisson's ratio d ...... Lattice spacing Δd of (111) plane...
・・・・・・Amount of change in lattice spacing due to ion implantation Therefore, under the condition that Hx-4πMs-ΔHx(U holds, the direction of spontaneous magnetization is parallel to the film surface. In this way, the direction of magnetization in ion implantation region 2 excluding connecting pattern 1 is parallel to the thickness of the implanted layer.Now, bubbles are generated along the connecting pattern by the magnetic field applied parallel to the garnet film surface. The bubbles are attracted to the charged wall 3 and transferred by the rotating magnetic field, but if the connected patterns are located close to each other, the bubbles jump over the gap between the connected patterns and move to the charged wall 1 of another connected pattern.

For example, in Figure 1 (when a magnetic field is applied in the direction of arrow 4 at V, the bubble 5 that is attracted by the charged wall and located at position A is a different slow hardening pattern if the interval between the connected patterns is narrow). The phenomenon of being attracted to the thousand-yard white oar located at the opening of 6 and position C is likely to occur.It is essential to eliminate such malfunctions in ion implantation devices, and this is due to the interaction between connected patterns. One way to reduce this is to form a two-level ion-implanted layer that reduces the concentration of the ion-implanted layer in the center between the connected patterns, but the process is complicated and the accuracy is poor. Therefore, the only way to reduce the interaction of charged walls between connected patterns is to make the cell size of the transfer pattern excessively large according to the bubble diameter.

ldl OBJECTS OF THE INVENTION An object of the present invention is to provide a method for reducing the interaction between transfer patterns in an ion implantation device to reduce memory cell size and achieve high density.

Let Structure of the Invention The object of the present invention is to irradiate a part between the transfer patterns with a laser to annealing this part, or to implant the part between the transfer patterns using a spacer mask provided with a window. This can be achieved by out-diffusion of ions, thereby locally lowering some anisotropic magnetic fields between the transfer patterns.

1f+ Embodiment of the invention Figure 2 shows the method of carrying out the invention, and 4 is a plan view or (
Bl and (Q are cross-sectional views. In other words, in the method shown in Figure 2, ions in the irradiated area are This is to reduce the injection-induced anisotropic magnetic field (ΔHK). Also, in the same figure (U is a spacer 10 with ΔHK formed by implanting hydrogen ions and neon ions, and the gap 9
After opening a window in a part 8 of the ion-implanted layer 11 by etching, heat treatment is performed to diffuse the implanted ions in the ion-implanted layer 11 in the window to the outside, thereby increasing the ΔH of the ion-implanted ff1ll in this part.
Decrease K. Figure 3 shows a sample 12 in which a spacer 10 made of 5K (S' (Jt)) of silicon dioxide was formed to a thickness of 2200 [A] using a sputtering method in an experiment to prove this.
The decreasing tendency of 7HK was measured by changing the heat treatment time for Sample 13 and Sample 13 in which no spacer was formed, and the heat treatment time was 30 minutes for each. From this result, the spacer layer 1O has the effect of suppressing the diffusion of implanted ions, and in this example, by performing heat treatment at 35UC℃: 5I (Jf
jHx of the part covered with fi spacer lO is approximately 3
There is no change at 200 [Ue,], but on the other hand, the implanted ions in the window brightness diffuse and the value of aHx decreases to 2500 [U+:]. In this way, by making a part of the ion implantation region between the transfer patterns into a region with small jH[l, the interaction between the transfer patterns can be reduced and bubble malfunction can be prevented, and the memory cell size can be reduced. can be reduced.

Furthermore, as a result of suppressing bubbles from popping out from the transfer pattern, as shown in FIG. This results in a shape shown by a solid line 18.

tgl Effects of the Invention The present invention was made to prevent malfunctions during bubble transfer by suppressing the interaction between transfer patterns in an ion implantation device. Using this method, we were able to reduce the interaction and reduce the memory cell size by locally reducing it.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of bubble transfer in an ion implantation device, IAI is a plan view, y is a cross-sectional view, FIG. 3 is an explanatory diagram showing the effect of heat treatment on ion implantation and conducting anisotropic magnetic field, and FIG. 4 is an explanatory diagram of the bias margin of bubble memory. pattern, 2 is an ion implantation region, 3 is a wall, 5 is a bubble, 7 is a transfer pattern, IO is a spacer.

Claims (1)

[Claims] (1) There is a transfer pattern formed by non-ion implantation on the epitaxially grown magnetic garnet film, and the transfer of magnetic bubbles is performed by attraction to a thousand yard wall generated along the transfer pattern by an applied magnetic field. In an ion implantation device, an ion implantation magnetic bubble device is characterized by locally lowering the anisotropic magnetic field of the ion implanted region between the transfer patterns. The ion implantation magnetic bubble device according to claim 1, characterized in that the ion implantation is carried out by locally raising the temperature of a part of the ion implantation region between the regions, and by the burn-out effect. Temperature is achieved by laser irradiation (4)
) The reduction of the anisotropic magnetic field is achieved by external diffusion of the implanted X-on from a spacer mask in which a part of the ion implantation region between the transfer patterns is opened. The ion-implanted magnetic bubble device according to item 1.