JPS62101012A - Magnetostatic-wave microwave element - Google Patents

Abstract

PURPOSE:To obtain a magnetostatic-wave microwave element using a YIG single crystal thin-film containing Pb for simultaneously making a change into a thick-film and low DELTAH (ferromagnetic resonance half-value width) compatible by mixing Pb contained in flux mainly comprising PbO-B2O3 into the single crystal film. CONSTITUTION:A gadolinium.gallium.garnet single crystal substrate is used, a single crystal film mainly comprising yttrium.iron.garnet is grown on the substrate through a liquid-phase epitaxial method while Pb contained in flux mainly comprising PbO-B2O3 is mixed into the single crystal film, and an LPE single crystal film in which the content of Pb is kept within a range of 1wt% or 2.25wt%, the lattice constant of the substrate is made larger than that of the formed single crystal film and the difference of these lattice constants is brought to 9X10<-3>Angstrom or less is employed. According to this invention, a YIG thick-film having low DELTAH can be formed by positively utilizing the mixing of Pb into flux even when No.5 additional element is not used actively with the exception of Fe, Y, Pb and B, thus manufacturing a magnetostatic-wave microwave element having low loss by employing the YIG thick-film.

Description

DETAILED DESCRIPTION OF THE INVENTION The field of industrial application is a magnetostatic microwave device using a YIG single-crystal thin film that has a small loss in microwaves.

Conventional technology Yttrium-iron-garnet (YIG; Y3F), which is an oxide magnetic material, is used for various microwave magnetic elements.
e s Ov ) is an important substance.

Its most striking property is the extremely high ferromagnetic resonance half-width ΔH
is narrow. Generally, YIG is provided to these microwave magnetic devices in the form of tilled lJi crystal spheres. The shape of the crystal is a single crystal thin film.

This is easy to manufacture and adaptable to planar electronic circuits. Naturally, if this is to be used in a microwave magnetic element, the single crystal thin film is required to have a line width as narrow as that of a sphere.

Early research on YIG single crystal III FJ was based on gadolinium gallium garnet (GGG; GGd
3Ga50I2) on the CV D (Chemica
It was epitaxially grown using the lV apcr D cposition method. It showed that Δl−1 is extremely narrow (ref.), F, 1v
lee etal, I EEE, 1-ran
, Mac, MAG-5<1969) P.

717), but Δ[-1 is not narrow for a spherical sample.

More recently, I P E (L 1quid phas
With the development of magnetic bubble domain devices, the process technology of the e E p-1 taxial method has reached a high level.

Using this LPE method, it has become possible to grow very high quality YIG single crystal thin films. The YIG single crystal thin film grown by this method has a value of 0. 1500, which is almost equal to the @good value of the spherical sample (Reference 1-(, l-, Glas
s etal, J, or Crystal
Gro-owth34 (1976) P, 285),
This seems to correspond to the limit of the "woody low Δl" that YIG crystals have. However, the ΔH of these films is not very reproducible and is said to be strongly dependent on the peaks of pb and pt mixed as impurities during the LPE process.

The invention solves the problem: YIGtti crystal itl l! l! From a practical standpoint when trying to use magnetostatic microwave devices,
Optimum manufacturing conditions cannot be discussed simply based on low ΔH. In addition, in magnetostatic microwave devices, it is necessary to be able to stably produce a thick film, and considering this condition, glass (Q1ass) and Elliott (Elliott)
As a result of the research, it was found that the optimum manufacturing conditions are not necessarily the same.

The ferromagnetic resonance half-width Δ1 is a physical quantity that is extremely structure sensitive. When compared with the magnetic permeability μ of soft magnetic materials used in the low frequency band, this can be formulated as μoc4πMs/ΔH−(i). μ is also an extremely structure-sensitive quantity.

There are several factors that are thought to cause the H content in the YIG single crystal n produced by the LPE method to be lower than the above-mentioned theoretical lower limit.

(1) It is considered that ΔH increases due to non-uniform anisotropy caused by internal stress within the single crystal thin film.

Further, causes of this internal stress include mismatching of lattice constants between the substrate and the produced single crystal thin film and fluctuations in the concentration of elements such as Y and Fe that occur with the LPE growth time.

(2) The inclusion of impurity elements that have a large effect of alleviating strong ta resonance is observed. Along with this, Fe atoms! l! Changes in lithium charge status also have an effect. For example, Pb” as an impurity
”, if 4,000 Pt is mixed, 2 F e34 → P l
) 2+10FQ 442 Fe 14-+Pt 4++
The illielectric state of F63+ changes as pe 2→, causing loss.

(3) Due to changes in the atmosphere during LPE, excess or deficiency of oxygen O may occur, and this may become a mechanism for relaxing ferromagnetic resonance.

〈4) Macroscopic film defects, such as aggregation of dislocations, bit or step-like growth defects, and surface roughness, also have Δ1
It is thought that this has an influence on increasing the size of ``.

The next problem is to create a reasonably high-quality LPE thick film.
In order to achieve this, it is necessary to suppress the internal stress generated during thick film fabrication to within the elastic limit.

In particular, the mismatch in lattice constant between the GGG base treatment and the produced film is an important factor.

An object of the present invention is to provide a magnetostatic microwave device using a YIG single-crystalline film containing Pb in order to achieve both thick film thickness and low ΔH at the same time by utilizing the Pb substitution effect. .

Means for Solving the Problems In order to solve the above problems, the present invention uses gadolinium.
Gallium Garnet! Using a 11-crystalline substrate, an ill crystal film containing yttrium, iron, and garnet as main components was grown on the substrate by a liquid phase epitaxial method, and an ill crystal film containing PbO-[3203 as a main component was grown on the substrate. f) mixing I) into a single crystal film;
The Pb content is in the range of 1 wt% to 2.25 wt%, the lattice constant of the M plate is larger than the lattice constant of the produced single crystal film, and the difference between them is 9 x 10-3 A or less. , Magnetostatic microwave device C using PE single crystal film
be.

Further, an LPE single crystal film whose growth temperature of the LPE is in the range of 850 to 950° C. is used.

Examples Table 1 shows the compositions of various LPE solutions used in the first example of the present invention.

Table 1. However, R4 is represented by the following formula and is the molar ratio of the solute to the total number of moles of the solution.

2 ([FQ203] + [Y2O3]) R4”--1111---------2
(↓F0203]+[Y2O3]+[13203])+
[LPE was performed using Pb01 solution. however,
The growth temperature Tg shown in Table 1 was selected so that the growth rate of the J'7 film was approximately 6 μm/min. As R4 increases, the growth temperature Tgb increases. FIG. 1 shows the results of experiment v1 of this example. Δa is the difference in lattice constant between the GGG substrate and the produced Y[G thin film, and was measured with an X-ray diffraction device.

When the GGG substrate is large, it is positive, and when the YIGM film is large, it is negative. R, + = 0.145, that is, the LPE film thin film produced at a growth temperature of 865°C is R, + = 0.145, Δa
It becomes +O. When the growth temperature is higher than this, Δa is positive, and when it is lower, it is negative.

Ferromagnetic half-width Δ1 required for magnetostatic microwave devices
It is desirable that it be as low as possible.

ΔH becomes smaller on the positive side than Δa−0, and ΔH was measured at a plant growth temperature of 850 to 9.03GH7.

Since HeH increases regardless of whether the growth temperature is higher or lower than this, the optimal growth temperature for low HeH is 850 to 950°C.
It can be said that.

Next, TPb was used as an impurity in the YIGI film grown in this example by EPM△ (E Icctron prob
It was analyzed using an eM 1cro Analyzer). However, the analytical values were calibrated using 100 wt% pure Pb metal.

As can be seen from FIG. 2, the decrease in the lattice constant mismatch Δa is due to the incorporation of Pb into the YIG thin film. P
Δa, which is obtained by extrapolation so that the amount of b mixed in is zero, is
There is approximately 0.019 A'c, which can be seen as the difference in lattice constant between the QGG substrate and the YIG thin film when no impurities are included.

As can be seen from this figure, the lattice constant mismatch Δa is about O~
ΔH almost shows the lowest value in the range of 0.009A. This is closely related to the degree of pb, 1 to 2.25
This is the same as Δ1-1 showing the lowest value in wt%. This value is similar to the literature value Q,5 previously reported by G1assf9.
It is about 2 to 4 times more than wt%, which clearly shows the characteristics of the present invention. The impurity other than Pb is Pt,
This is less than iwt%, and in this example, j)suΔ1-
It is thought that there is no woody relationship with the reduction of 1.

FIG. 3 does not show an embodiment of the invention. YIG thin films of various thicknesses were prepared from solutions with various compositions shown in Table 1, and the horizontal axis was plotted vertically with respect to the film thickness, focusing on the fact that film cracking occurs when the thin film becomes thick to a certain extent. axis to lattice constant mismatch Δ
This is something organized for a. An O mark indicates a case where the film did not crack, and an X mark indicates a case where the film cracked. As can be seen from this figure, when Δa becomes smaller, it becomes difficult to break even when the film thickness becomes thicker. ΔaI)<0.01
For those of A or higher, films with a thickness of 10 μm or more always cracked.

From this, it can be seen that a magnetostatic microwave element with a thickness of 20 μm
Since lattice constants in the vicinity or higher are often used, it can be said from this fact that Δa <0.009Δ is a state of optimal lattice constant mismatch. This is consistent with the range of Δa required from the optimal value of Δ(−1).

Effects of the invention Tree R Akini J: n. Even without actively using a fifth additive element other than Fe, Y, Pb, and B, it is possible to actively utilize the inclusion of Pb in the flux to achieve low ΔTo1 rightward Y
It is possible to fabricate a thick film of IG, and using this, a magnetostatic microwave device with low loss can be fabricated.

[Brief explanation of drawings]

Figure 1 9 Figure 2 shows an example of the present Jl Light
FIG. 3 is a characteristic diagram of a film showing another embodiment of the present invention.

Claims (2)

[Claims] (1) Using a single crystal substrate of gadolinium, gallium, and garnet, a liquid phase epitaxial method is applied on the substrate.
A single-crystal film containing yttrium, iron, and garnet as main components is grown, and Pb contained in a flux containing PbO-B_2O_3 as a main component is mixed into the single-crystal film so that the content of Pb is 1 wt% to 2. 25 wt%, the lattice constant of the substrate is larger than the lattice constant of the produced single crystal film, and the difference between them is 9×10^-^3A or less. Magnetic microwave element. (2) A magnetostatic microwave device according to claim 1, which uses an LPE single crystal film in which the LPE growth temperature is in the range of 850 to 950°C.