JPH06303088A - High frequency circuit element - Google Patents

Abstract

PURPOSE:To provide a high frequency circuit element in which a surface acoustic wave can be positively fetched and absorbed between a pair of grooves. CONSTITUTION:In a high frequency circuit element in which a surface acoustic wave element 2 and the other elements are combined and formed on a same substrate 1, and a blocking part which blocks the propagation of the surface acoustic wave to the other element is formed on the substrate 1. In the blocking part, a pair of grooves 4 whose inclined directions against the proceeding direction of the surface acoustic wave are alternatively changed are successively formed like a saw-tooth so that they can be adjacent while each inclination less than 5 deg. can be held against the proceeding direction of the surface acoustic wave.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency circuit element used in a high frequency circuit, and more particularly to a surface acoustic wave element having a function of exciting and receiving a surface acoustic wave on the same substrate. The present invention relates to a high-frequency circuit element arranged in.

[0002]

2. Description of the Related Art In recent years, mobile phones, MCA (Multi Channel)
Access) With the spread of mobile radios used in a high frequency range of several hundred MHz to several GHz, wireless devices are required to be small and lightweight, and inevitably also for components used in these wireless devices. It is desired to reduce the size and weight. In particular, it cannot be said that the high-frequency amplifier circuits and filters that handle signals in the high-frequency range are smaller and lighter than LSIs used for normal signal processing, and currently, parts used in such high-frequency ranges are used. There is a strong demand for smaller size and lighter weight.

Among them, the surface acoustic wave element using the piezoelectric body can be made smaller and lighter than the coaxial filter and the helical filter which have been used so far, so that the high frequency component can be made smaller and lighter. Is attracting attention as it advances. This surface acoustic wave device is not manufactured as a single filter, but is formed by forming a piezoelectric thin film such as aluminum nitride on another part of the semiconductor substrate on which a high frequency amplifying device is formed. A high frequency integrated circuit device formed with an acoustic wave device has been proposed (for example, Tsubouchi K; IEEE Trans.Sonics.Ultrason.
Vol.32, No.5, P634 (1985)).

However, when the high frequency amplifying element and the surface acoustic wave element are thus provided on the same substrate, the surface acoustic wave from the surface acoustic wave element is transmitted to the peripheral elements such as the high frequency amplifying element on the substrate. However, there is a problem in that the characteristics of the circuit are deteriorated due to the interference with each other.

Conventionally, as a measure for preventing the influence of the propagation of the surface acoustic wave on other elements on the same substrate when the high frequency amplification element and the surface acoustic wave element are formed on the same substrate, for example, It has been proposed to form a groove or a hole around a piezoelectric thin film forming a surface acoustic wave element to scatter the surface acoustic wave, or to absorb the surface acoustic wave by an absorbing material (Actual publication 57). 50813
Japanese Patent Laid-Open No. 2-25104, Japanese Patent Laid-Open No. 3-14
5320).

[0006]

However, in the conventional high frequency circuit element as described above, the surface acoustic wave from the surface acoustic wave element is scattered by the grooves or holes, so that the reflected surface acoustic wave is generated. Although the wave level is reduced, the effect of surface acoustic waves on other elements is not completely eliminated, and there is still the risk of interference between scattered surface acoustic waves and other elements. Further, in the method using the absorber, since resin or the like is usually used as the absorber, it is likely to cause contamination of the semiconductor substrate. Contamination should be avoided as much as possible when manufacturing semiconductor devices,
It is desired to prevent interference without using an absorber such as resin.

The present invention has been made in view of the above-mentioned problems of the prior art. Instead of scattering the surface acoustic wave, the surface acoustic wave is positively taken between and absorbed by a pair of linear grooves. An object of the present invention is to provide a high-frequency circuit element having a groove configured as described above.

[0008]

According to the present invention for achieving the above object, a composite element including at least one surface acoustic wave element is formed on the same substrate, and other than the surface acoustic wave element is formed on the substrate. A high-frequency circuit element in which an element portion for preventing the propagation of the surface acoustic wave to other elements is formed, wherein the groove alternately changes the inclination direction with respect to the traveling direction of the surface acoustic wave in the traveling direction. A pair of straight extending grooves are formed continuously in a saw-tooth shape adjacent to each other so as to maintain a constant inclination angle with respect to the traveling direction of the surface acoustic wave, and the inclination angle of the groove Is less than 5 degrees with respect to the traveling direction of the surface acoustic wave.

The blocking portion has a curved groove convex toward the pair of surface acoustic wave elements extending in the traveling direction by alternately changing the inclination direction with respect to the traveling direction of the surface acoustic wave. With respect to each other so as to maintain a constant inclined shape, is formed continuously in a shape similar to a saw blade, and the maximum value of the inclination angle of the groove, It is characterized in that it is set to 5 degrees or less with respect to the traveling direction.

[0010]

According to the present invention having such a configuration, the surface acoustic wave from the surface acoustic wave device formed on the same substrate is not affected by the surface acoustic wave device and the other surface acoustic wave device. Absorbed by the blocking part provided between the element,
Be blocked.

That is, in the blocking portion, a pair of straight grooves extending in the traveling direction by alternately changing the inclination direction with respect to the traveling direction of the surface acoustic wave has a constant inclination with respect to the traveling direction of the surface acoustic wave. It is formed so as to be adjacent to each other in a saw-tooth shape so as to maintain an angle, and the inclination angle of the groove is 5 degrees or less with respect to the traveling direction of the surface acoustic wave. The surface acoustic wave traveling toward this groove repeats multiple reflection between the pair of grooves, and is attenuated while repeating this multiple reflection. As a result, even if it returns in the opposite direction, its level is extremely lowered, so that the influence on other elements is significantly reduced.

In the blocking portion, a curved groove convex toward the pair of surface acoustic wave elements extending in the traveling direction by alternately changing the inclination direction with respect to the traveling direction of the surface acoustic wave is formed in the traveling direction of the surface acoustic wave. On the other hand, it is formed continuously in a shape similar to a saw blade adjacent to each other so as to maintain a constant inclined shape, and further, the maximum value of the inclination angle of the groove is equal to that of the surface acoustic wave. If it is set to 5 degrees or less with respect to the traveling direction, the surface acoustic wave traveling toward this groove will repeat multiple reflection between the pair of grooves, and while repeating this multiple reflection. Decays. As a result, even if it returns in the opposite direction, its level is extremely lowered, so that the influence on other elements is significantly reduced.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings.

Example 1. 1 is a top view of a first embodiment of a high frequency circuit device according to the present invention. In this high-frequency circuit element, a surface acoustic wave element 2 is formed on a piezoelectric thin film (not shown) formed on a part of a silicon substrate 1, and a semiconductor thin film (not shown) also formed on another part of the silicon substrate 1 is formed. The high frequency amplification element 3 is created. High frequency amplifier 3
May be formed on the silicon substrate 1. The input electrode 2A and the output electrode 2 that form the surface acoustic wave element 2
B is formed on the piezoelectric thin film by photolithography or the like. These input / output electrodes 2A and 2B may be formed under the piezoelectric thin film, that is, on the silicon substrate 1. These input / output electrodes 2A and 2B form a filter having a predetermined frequency characteristic. Electrode 2 provided between input electrode 2A and output electrode 2B
C is an electrode for controlling the insertion loss of the surface acoustic wave element 2, but this electrode may be omitted. In the surface acoustic wave element 2, a surface acoustic wave is generated from the input electrode 2A and propagates in the piezoelectric thin film toward the output electrode 2B,
It is absorbed by the output electrode 2B. However, the output electrode 2B
The surface acoustic wave that has not been completely absorbed because of the absorption is propagated toward the high frequency amplification element 3. Between the surface acoustic wave element 2 and the high frequency amplifier element 11 of the high frequency circuit element of the present invention, the propagation of the surface acoustic wave from the surface acoustic wave circuit element 2 is blocked so as not to propagate to the amplifier circuit element 3. A groove 4 is provided as a blocking portion. As shown in FIG. 2, which is an enlarged view of the groove 4, the groove 4 extends in the traveling direction of the surface acoustic wave by alternately changing its inclination direction with respect to the traveling direction of the surface acoustic wave. On the other hand, adjacent saw blades are continuously formed so as to maintain a constant inclination angle. Further, the inclination angle of the groove 4 with respect to the traveling direction of the surface acoustic wave is set to 5 degrees or less. The number of 5 degrees is not a number having a critical meaning, but if it is provided at an angle less than this, the effect of blocking surface acoustic waves becomes high.

That is, as shown in FIG. 2, the inclination angle θ of the groove 4 is
Is less than or equal to 5 degrees, the surface acoustic wave propagated from the surface acoustic wave circuit element 2 repeats multiple reflections so as to be drawn between the grooves 4 whose inclination directions are different from each other. The surface acoustic wave traveling toward the amplifier circuit element 3 will be attenuated very efficiently. If the groove 4 is provided at such an angle that the surface acoustic wave is drawn in, the reflected wave does not return in reverse, so that the surface acoustic wave can be effectively absorbed. Become.

Example 2. In the embodiment, as shown in FIG. 3, which is an enlarged view of the groove 4, a pair of linear grooves extending in the traveling direction by alternately changing the inclination direction with respect to the traveling direction of the surface acoustic wave is used. Adjacent saw blades are continuously formed in a shape similar to a saw blade so as to maintain a constant inclined shape with respect to the traveling direction of the surface acoustic wave.
The maximum value of the inclination angle of the groove 4 with respect to the traveling direction of the surface acoustic wave is 5 degrees or less. The surface acoustic wave propagated from the surface acoustic wave circuit element 2 has grooves 4 having different inclination directions alternately.
The multiple reflections are repeated so as to be drawn in between, and the surface acoustic waves toward the amplifier circuit element 3 are attenuated very efficiently while the multiple reflections are repeated. In addition, as the surface acoustic wave goes deeper in the part sandwiched by the groove 4, it becomes more difficult for the surface acoustic wave to return in the opposite direction. Therefore, the reflected wave becomes less likely to return in the opposite direction, so that the surface acoustic wave is absorbed more effectively. can do.

Also in the first and second embodiments, the cross-sectional shape of the groove 4 may be any of a quadrangle, a triangle, a trapezoid, etc., as shown in FIG. It is sufficient to select the most suitable one in consideration of such factors.

[0018]

As is apparent from the above description, according to the present invention, the groove is provided at an angle capable of absorbing the surface acoustic wave from the surface acoustic wave element. Can be suppressed to a minimum, and surface acoustic waves can be absorbed without using an absorber that causes semiconductor contamination.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the structure of a high-frequency circuit element of the present invention.

FIG. 2 is a diagram showing a shape of a groove formed in the high-frequency circuit element of the present invention.

FIG. 3 is a diagram showing another example of a groove formed in the high-frequency circuit element of the present invention.

FIG. 4 is a diagram showing an example of a cross-sectional shape of the groove shown in FIG.

[Explanation of symbols]

 1 ... Silicon substrate 2 ... Surface acoustic wave element 3 ... High frequency amplification element 4 ... Groove

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[Procedure amendment]

[Submission date] June 11, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction content]

The blocking portion has a curved groove convex toward the pair of surface acoustic wave elements extending in the traveling direction by alternately changing the inclination direction with respect to the traveling direction of the surface acoustic wave. On the other hand, it is formed continuously in a shape similar to a saw blade adjacent to each other so as to maintain a constant inclined shape, and further, the maximum value of the inclination angle of the groove is equal to that of the surface acoustic wave. In the case where the angle is set to 5 degrees or less with respect to the traveling direction, the surface acoustic wave traveling toward the − groove is repeatedly reflected multiple times between the pair of grooves, and while the multiple reflection is repeated, Decays to. It
In addition, the deeper the surface acoustic wave goes into the pair of grooves, the more
Since hardly back in the opposite direction, because also the levels when there is a return in the opposite direction is reduced in further, the effect on the other elements smaller in further.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

Example 2. In an embodiment, the grooves 4, as shown in FIG. 3 is an enlarged view thereof, the grooves of the pair of curve which extends in the traveling direction by changing the inclination direction with respect to the traveling direction of the surface acoustic wave alternating Adjacent saw blades are continuously formed in a shape similar to a saw blade so as to maintain a constant inclined shape with respect to the traveling direction of the surface acoustic wave.
The maximum value of the inclination angle of the groove 4 with respect to the traveling direction of the surface acoustic wave is 5 degrees or less. The surface acoustic wave propagated from the surface acoustic wave circuit element 2 has grooves 4 having different inclination directions alternately.
The multiple reflections are repeated so as to be drawn in between, and the surface acoustic waves toward the amplifier circuit element 3 are attenuated very efficiently while the multiple reflections are repeated. Further, as the surface acoustic wave goes deeper in the portion sandwiched by the groove 4, it becomes more difficult for the surface acoustic wave to return in the opposite direction, so that the reflected wave becomes less likely to return in the opposite direction, so that the surface acoustic wave is absorbed more effectively. can do.

Claims (2)

[Claims] 1. A composite element including at least one surface acoustic wave element formed on the same substrate, and a blocking element for preventing propagation of surface acoustic wave to other elements other than the surface acoustic wave element on the substrate. In the high-frequency circuit element in which a portion is formed, the blocking portion has a pair of straight grooves extending in the traveling direction by alternately changing the inclination direction with respect to the traveling direction of the surface acoustic wave. The grooves are adjacent to each other so as to maintain a constant inclination angle with respect to the direction, and are continuously formed in a shape similar to a saw blade, and the maximum value of the inclination angle of the groove is the same as that of the surface acoustic wave. A high-frequency circuit element characterized in that the angle is 5 degrees or less with respect to the traveling direction. 2. The blocking portion has a curved groove convex toward the pair of surface acoustic wave elements extending in the traveling direction by alternately changing the inclination direction with respect to the traveling direction of the surface acoustic wave. Adjacent to each other so as to maintain a constant inclined shape with respect to the direction, and continuously formed in a shape similar to a saw blade, and the maximum value of the inclination angle of the groove is The high frequency circuit element according to claim 1, wherein the high frequency circuit element is set at 5 degrees or less with respect to the traveling direction.