JP2945035B2 - Manufacturing method of magnetostatic wave element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to a method for manufacturing a magnetostatic wave element, particularly, a frequency of 100 MHz.
The present invention relates to a method for manufacturing a magnetostatic wave device having a low insertion loss and used in a microwave band from to several tens of GHz.

The (prior art) magnetostatic wave element used in a microwave band of several 10GHz from the frequency 100 MHz, on a substrate of formula (YGdGa) ₈ O ₁₂ as for example shown in FIG. 4 (LaYFeGa) ₈ Forming two meander-type aluminum electrodes on the surface of the magnetic material on which the magnetic film represented by O ₁₂ is grown by the epitaxial method;
It is known that a magnetostatic wave signal is input to this under an external magnetic field.

(Problems to be Solved by the Invention) However, since only a device having a large insertion loss is obtained with this known magnetostatic wave device, it is required to provide a device having a low insertion loss.

(Means for Solving the Problems) The present invention relates to a method for manufacturing a magnetostatic wave device that has solved the above problems, and this method is based on the formula (LaYFeGa) on a substrate single crystal represented by the formula (YGdGa) ₈ O _12. A magnetic material obtained by epitaxially growing a magnetic film represented by ₈ O ₁₂ has a square or rectangular shape, and its end face is parallel or perpendicular to a parallel strip transducer to act as a reflector.

Namely, the present inventors have studied a result a method for producing a low magnetostatic wave device insertion loss, Equation (YGdGa) ₈ O
The magnetic material is grown magnetic film shown on a substrate made of ₁₂ the formula (LaYFeGa) ₈ O ₁₂ as a prismatic shape, such as square or rectangular, so as to be parallel or perpendicular to this parallel strips transducer When the end face acts as a reflector, it is found that the insertion loss is remarkably improved, and it is confirmed that the magnetic material should be as described above. Completed.

 This will be described in more detail below.

(Operation) The magnetostatic wave device according to the present invention is configured, for example, as shown in FIG. FIG. 1A is a longitudinal sectional view of the magnetostatic wave element of the present invention, and FIG. 1B is a plan view of the magnetostatic wave element. As shown in FIG. A parallel strip transducer is arranged at the center of the alumina substrate, signal input electrodes and signal output electrodes are provided on the left and right sides, and a magnetic film is grown on the garnet single crystal substrate by epitaxy on the parallel strip transducer. This magnetic film has a saturation magnetization of 1,000 G or less because this magnetic film can handle a large magnetostatic wave power. This magnetic material has a rectangular shape as shown in FIG. 1 (b).

In this magnetostatic wave element, the distance L between the input electrode and the output electrode of the parallel strip transducer is in the range of 0.5 to 1.5 mm in order to reduce the propagation loss of the magnetostatic wave. The length (W) of the side in the electrode direction is in the range of L ≦ W ≦ 21. The radiation resistance of this parallel strip transducer is 10
If it is set to a value other than 200 Ω, the insertion loss becomes 6 dB or more due to mismatching. Therefore, it is necessary to set the range to 10 to 200 Ω. However, the preferable value should be 50 Ω. The value of the side (D) may be a length that allows a desired value to be obtained within the above-described radiation resistance of 10 to 200Ω of the parallel strip transducer.

The magnetic material used here may be a magnetic film formed by epitaxially growing a magnetic film on a garnet substrate single crystal. The magnetic material for manufacturing the magnetostatic wave device according to the present invention has the formula (YGdGa) ₈ O the magnetic film shown on a substrate single crystal by the formula (LaYFeGa) ₈ G ₁₂ indicated by ₁₂ are those obtained by epitaxial growth.

Since this garnet substrate single crystal is represented by (YGdGa) ₈ O ₁₂ , it is represented by YaGd _ba Ga _8-b O _12, where a is 0.6 ≧ a> 0 and b is 3.1 ≧ b> 3.0. This is the number shown, which is the Y and Gd in the [c] site,
It is assumed that a part of Y and Ga are arranged at the [a] site, and Ga is arranged at the [d] site, which has the formula Y _0.6 Gd _2.55 Ga
_4.95 O ₁₂ , Y _0.3 Gd _2.71 Ga _4.99 O ₁₂ are exemplified. This is, for example, 3.5 to 7.5 mol% of Y ₂ O ₃ , Gd ₂ O ₃ 3
A crucible is charged with 0 to 34 mol% and 61 to 63 mol% of Ga ₂ O ₃ , heated to 1,730 ° C. by high-frequency induction and melted, and then obtained by pulling a single crystal from this solution by the Czochralski method. Can be. In addition, it was confirmed that, when a wafer cut out of this single crystal was etched with hot phosphoric acid, for example, and measured for a lattice constant, it showed 12.367 to 12.383 °.

Further, an epitaxial film _{(La Y Fe Ga) 8 O} 12 has the composition formula _{La x Y yx Fe z Ga 8} -yz O 12 grown on the substrate single crystal
Where x, y, and z are 0.1 ≧ x> 0, 3.1>y> 3.
0, 4.1>z> 3.6, which are La and Y at the [c] site, Fe and Y and a part of Ga at the [a] site, and Fe and Ga at the [d] site. Which has the formula La _0.04 y _3.00 Fe _3.86 Ga _1.10 O ₁₂ , La _0.1 Y _2.9 Fe _3.78 Ga
_1.15 O ₁₂ is exemplified. This one has a lattice constant of 12.36
3-12.372Å, and the lattice constant of the substrate single crystal on which this is epitaxially grown is 12.3 as described above.
Since it is 63 to 12.383 ° and the lattice constants of the two coincide within a range of ± 0.03 °, there is no mismatch, epitaxial growth can be easily performed, and the obtained epitaxially grown layer does not crack.

Note that this epitaxial growth may be performed by a liquid phase method, and therefore, La ₂ O ₃ , Y ₂ O ₃ , Fe ₂ O ₃ , and Ga ₂ O ₃ are combined with the flux components PbO and B ₂ O ₃ by a platinum crucible. And melted by heating to 950 to 1,100 ° C., and immersing the substrate single crystal in the melt. The thickness of the epitaxial layer formed by the epitaxial growth method is related to the bandwidth of the device, but is usually in the range of 5 μm to 100 μm.

The magnetostatic wave device according to the present invention is made by placing this magnetic material in a square or rectangular shape and mounting it on a parallel strip transducer, which has significantly lower insertion loss than conventional products. The advantage is provided.

(Examples) Next, examples of the present invention and comparative examples will be described.

Example On a garnet single crystal represented by the formula (YGdGa) ₈ O ₁₂ , a formula (saturation magnetization: 370 G, film thickness: 65 μm, and magnetic resonance half width (△ H) measured at 9.2 GHz: 20 e) LaYFeG
a) A magnetic material represented by ₈ O ₁₂ was epitaxially grown to produce a magnetic material, which was cut into 1.2 × 3.5 mm and 1.2 × 3.3 mm.

Next, the magnetic material was placed on a parallel strip transducer made of Au, having three electrode pairs, a counter electrode width of 50 μm, an electrode interval of 50 μm, and a power transmission parallel strip transducer of 0.6 mm. Were adhered so that the long side was parallel to the parallel strip transducer and the center thereof coincided with the center lines of the two parallel strip transducers, thereby producing a magnetostatic wave device as shown in FIG.

Next, the device was placed in a small electromagnet, and a magnetic field of up to 2,000 G was applied perpendicularly to the magnetic film of the magnetic material. The relationship between the frequency and the insertion loss was examined, as shown in FIG. The minimum insertion loss was obtained from the result, and the minimum insertion loss was measured by changing the frequency. The result as shown in FIG. 3 was obtained. At 4.0GHz and for B
It was confirmed that a frequency variable filter having a low insertion loss of 5 to 10 dB at 1.3 to 3.0 GHz can be formed.

However, for comparison, (YGdGa) ₈ O ₁₂
Using a magnetic film obtained by epitaxially growing a magnetic film having a composition of (LaYFeGa) ₈ O ₁₂ on a single-crystal substrate, the insertion loss of a magnetostatic wave device configured as shown in FIG. 4 was examined. However, this showed the result as shown in FIG. 5, and the minimum insertion loss also showed 20 to 27 dB at 0.5 to 3 GHz as shown in FIG.

(Effects of the Invention) The present invention relates to a method for manufacturing a magnetostatic wave device having a low insertion loss, in which a magnetic material in contact with a parallel strip transducer disposed on a substrate is square or rectangular, and the end face thereof is parallelized. in the parallel or perpendicular to the strip transducer is characterized in that to act as a reflector, further the magnetic material has the formula (YGdGa) ₈ formula (LaYFeGa) garnet single crystal substrate represented by O _{12 8} O It is assumed that the magnetic film shown by ₁₂ is epitaxially grown, but since the magnetostatic wave element has a remarkably improved insertion loss, the frequency is 100M.
This has the advantage that a magnetostatic wave element used in the microwave band from Hz to several tens of GHz can be easily obtained.

[Brief description of the drawings]

1 (a) is a longitudinal sectional view of a magnetostatic wave device according to the present invention, FIG. 1 (b) is a plan view thereof, and FIG. 2 is a graph showing the frequency and insertion loss of the magnetostatic wave device of the present invention shown in the embodiment. Relationship graph, third
FIG. 4 is a graph showing the relationship between the frequency and the minimum insertion loss of the magnetostatic wave element of the present invention shown in the embodiment and the known magnetostatic wave element shown in the comparative example. FIG. 4 is a perspective view of a conventionally known magnetostatic wave element. FIG. 5 is a graph showing the relationship between the frequency and the insertion loss of a conventionally known magnetostatic wave element.

Continuation of the front page (56) References JP-A-1-152604 (JP, A) JP-A-62-294001 (JP, A) JP-A-52-87954 (JP, A) JP-A-1-91324 (JP) , U) Journal of the Institute of Television Engineers of Japan, Vol. 38, No. 12 (1984), pp 1053-1062, “Trends in Magnetostatic Wave (MSW) Devices,” by Kazumi Utsumi, Makoto Tsutsumi 1989 IEICE Autumn National Convention Proceedings, Lecture Number SC-9-4, “High Low Loss Magnetostatic Wave Filter with Suppressed Next Mode ”, Toshio Nishikawa et al. 2-361 to 2.362, August 15, 2001

Claims (5)

(57) [Claims] 1. A type of magnetic material of the magnetic layer is epitaxially grown of formula (LaYFeGa) ₈ O ₁₂ on a substrate a single crystal represented by (YGdGa) ₈ O ₁₂ a square or rectangular parallel strips trans the end face A method of manufacturing a magnetostatic wave device which is parallel or perpendicular to a juicer and acts as a reflector. 2. The method according to claim 1, wherein the saturation magnetization of the magnetic film is 1,000 G or less. 3. The magnetostatic wave device according to claim 1, wherein the length W of the side of the magnetic material in the electrode direction is L ≦ W ≦ 21 in relation to the distance L between the input electrode and the output electrode of the parallel strip transducer. Manufacturing method. 4. The method according to claim 3, wherein L is 0.5 to 1.5 mm. 5. The method according to claim 1, wherein the radiation resistance of the parallel strip transducer is 10 to 200Ω.