JPS5851690B2 - Gap holding column for surface acoustic wave device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gap holding column for a surface acoustic wave device that maintains a gap between a semiconductor and a piezoelectric body of a surface acoustic wave nonlinear device.

In a surface acoustic wave device that holds a semiconductor substrate and a piezoelectric substrate with an air gap between them, when a dielectric pillar or a pillar with irregularities on the substrate itself is used to maintain the air gap, conventionally the arrangement of this pillar is Regarding (1) ordering regularly, (2)
A method of arranging them randomly in one dimension was used.

FIG. 1 is a conceptual diagram of a pillar for maintaining air gaps.

Here, pillars made by etching or the like on the substrate itself are shown.

FIGS. 2a and 2b are plan views of FIG. 1, and black circles in the figures indicate pillars.

If Figure 2a is (1) above, Figure 2a is (2) above.
).

In both cases, surface acoustic waves are incident from the direction of the arrow.

In Figure 2a, the pillars are arranged regularly, and have regularity not only in the direction of wave incidence but also in the diagonal direction.
The incident wave is strongly reflected in the opposite direction, and is also diffracted in a specific direction determined by the regularity.

In Figure 2, the pillars are arranged randomly in the wave incident direction so that there is no periodicity in that direction, making it difficult for surface waves to be strongly reflected in the opposite direction, and there is no regularity in the diagonal direction. .

Although it has the above structure, if the incident direction of the surface waves deviates from the set direction, or if you want to make two surface waves incident in two orthogonal directions, use the structure shown in Figure 2. It is clear that the structure also suffers from the drawbacks shown in FIG. 2a.

For example, in FIG. 2, when surface waves are incident from two directions, the direction of the arrow and the direction perpendicular thereto, reflection will occur in the latter direction due to the periodic arrangement of columns.

In order to eliminate the above-mentioned drawbacks, the present invention provides a space for a surface acoustic wave device in which the arrangement of columns is two-dimensionally random, and even if surface waves are incident from any direction, the waves are not reflected or diffracted in a specific direction. The present invention provides a holding column, which will be described in detail below with reference to the drawings.

FIG. 3 shows an embodiment of the present invention, and shows a plan view similar to FIG. 2.

1 is a piezoelectric substrate, 2 is a column, 3 is a lattice pattern provided on the substrate for explanation (horizontal axis X, vertical axis Y), and A is a lattice point for explanation.

The arrangement of columns in the figure will be explained. At the lattice points shown in the figure, consider the X-axis and y-axis with each lattice point as the center.

Now, at grid point A, the column coordinates (Xl,
yl).

Similarly, the coordinates of the pillars for other grid points are determined using random numbers to form an arrangement as shown in FIG.

Because of this structure, there is no regularity in the X-axis direction, Y-axis direction, or other directions, so even if waves are incident from any direction, the waves will be reflected in a specific direction.・This will prevent diffraction.

FIG. 4 also shows an embodiment of the invention, in which 1 is a piezoelectric substrate, 2 is a column, 4 is a fan-shaped grid provided on the substrate for explanation (radial direction coordinate r1 angular coordinate θ), and B is an illustration for explanation. Shows grid points.

At grid point B, a reference radius r is set using a random number.

and the reference angle θ. Determine the position of the pillar by finding the deviation from

The same process is performed for other lattice points to determine their arrangement without regularity in any direction.

Because of this structure, even if waves are incident from any direction, the waves will not be reflected or diffracted in a specific direction.

FIG. 5 shows an example of a device using the pillar arrangement of the present invention.

1 is a piezoelectric substrate, 5 is a two-dimensionally randomly arranged pillar region (a semiconductor device is placed in this region), and 6 and 7 are elastic surface liquid-filled quadrant transducers.

6/, 7/ are elastic surface liquid extraction quadrant juicers.

The output is obtained by a 6z7t elastic surface liquid ejection transducer or from an electrode on the semiconductor side, but in any case, the surface waves are two orthogonal waves.
Due to the dimensionally randomly arranged pillars, the light is not diffracted in a specific direction and interacts uniformly with each other.

FIG. 6 shows an example of a device using the pillar arrangement of the present invention, where 1 is a piezoelectric substrate, 5 is a region of pillars arranged two-dimensionally at random (semiconductor devices are placed here, as shown in FIG. 5). is the same as

) 6, 7.8 is an elastic surface liquid filled quadrant juicer, 6'
, 7', 8' are elastic surface liquid extraction quadrant juicers.

The output is obtained from 6', 7', and 8' as in FIG. 5, or alternatively from the electrode on the semiconductor side.

The surface waves are input as three waves, but as in FIG. 5, they act uniformly on each other without being diffracted in a specific direction.

As explained above, according to the present invention, the arrangement of the pillars for maintaining the air gap is two-dimensionally random.
It has the advantage of not reflecting or diffracting surface waves in a specific direction even if the surface waves are incident from any direction.

[Brief explanation of drawings]

Figure 1 is a conceptual diagram of the gap-maintaining pillar of the surface acoustic wave device, Figure 2
Figure a is a plan view showing the arrangement of regularly arranged pillars of a conventional surface acoustic wave device, and Fig. 2 shows the arrangement of pillars arranged randomly in one dimension in a conventional surface acoustic wave device. 3 is a plan view showing one embodiment of the present invention, FIG. 4 is a plan view showing another embodiment of the present invention, and FIGS. 5 and 6 are surface acoustic waves according to the present invention, respectively. FIG. 1 is a configuration diagram showing an example of a device. 1... Piezoelectric substrate, 2... Pillar, 3...
... Lattice pattern for explanation, 4... Fan-shaped grid pattern for explanation, 5... Area of pillars arranged two-dimensionally, 6.7, 8... ...Elastic surface liquid filled quadrant juicer, 6/, 7/, 8/...
...Elastic surface liquid extraction cadence juicer.

Claims (1)

[Claims] 1. By holding the semiconductor substrate and the piezoelectric substrate with a gap between them, and by creating irregularities on the metal or dielectric pillars and the substrate itself in order to maintain the gap on the main surface of the piezoelectric substrate facing the semiconductor substrate. A gap maintaining column for a surface acoustic wave device in which columns are formed as spacers, wherein the columns are two-dimensionally arranged at random.