TWM618737U - Suspending piezoelectric ultrasonic sensor - Google Patents

Abstract

A suspension type piezoelectric ultrasonic sensor includes a semiconductor substrate and a piezoelectric ultrasonic sensor element. The semiconductor substrate includes a columnar arrangement area, a peripheral wall, and at least one bridge portion. A cavity is formed between the columnar arrangement area and the peripheral wall. The cavity surrounds the columnar arrangement area. The bridge portion connects the columnar arrangement area and the peripheral wall. The piezoelectric ultrasonic sensing element is arranged on the columnar arrangement area. By arranging the cavity and the bridge portion on the semiconductor substrate, the required frequency can be adjusted in this way, and then the required sound pressure and emission angle can be adjusted, providing a larger process margin.

Description

Suspended piezoelectric ultrasonic sensor

This creative department relates to the field of sensing, in particular to a floating piezoelectric ultrasonic sensor.

However, in the prior art, the vacuum cavity of the ultrasonic sensor is enclosed inside the ultrasonic sensor. After the ultrasonic sensor is manufactured, the volume of the cavity is fixed, and the corresponding transmitter is also fixed. The resonant frequency of the wave. However, sometimes the resonance frequency of the ultrasonic sensor cannot reach the required emission angle and sound pressure, so it needs to be redesigned. In addition to the high cost, for example, the size required for an ultrasonic sensor is smaller nowadays, the cavity space must also be reduced, and the overall design is more restricted by the process margin.

In order to solve the problems faced by the prior art, a floating piezoelectric ultrasonic sensor is provided here. The floating piezoelectric ultrasonic sensor includes a semiconductor substrate and a piezoelectric ultrasonic sensor element. The semiconductor substrate includes a columnar arrangement area, a peripheral wall, and at least one bridge portion. A cavity is formed between the columnar arrangement area and the peripheral wall. The cavity surrounds the columnar arrangement area. The bridge portion connects the columnar arrangement area and the peripheral wall. The piezoelectric ultrasonic sensing element is arranged on the columnar arrangement area.

In some embodiments, the semiconductor substrate further includes at least one through hole, which penetrates the semiconductor substrate and communicates with the cavity.

In more detail, in some embodiments, the through hole is adjacent to the columnar arrangement area.

In more detail, in some embodiments, the semiconductor substrate includes a plurality of through holes, the through holes penetrate the semiconductor substrate and are distributed around the columnar arrangement area, and the through holes communicate with the cavity.

In some embodiments, the semiconductor substrate includes a plurality of bridge portions, and each bridge portion is respectively connected to the columnar arrangement area and the peripheral wall.

In more detail, in some embodiments, the bridge portion is symmetrically located around the columnar arrangement area.

In some embodiments, the width of the piezoelectric ultrasonic sensing element is smaller than the columnar arrangement area.

In some embodiments, the thickness of the semiconductor substrate is 200 to 700 um.

In some embodiments, the length of the bridge portion is less than 1000um.

As described in the foregoing embodiment, after the piezoelectric ultrasonic sensor element is completed, a cavity is further provided on the semiconductor substrate, and the columnar arrangement area where the piezoelectric ultrasonic sensor element is arranged is connected to the columnar arrangement area of the piezoelectric ultrasonic sensor element through the remaining bridge portion. The peripheral wall can adjust the required resonant frequency through this method, and then adjust the required sound pressure and emission angle, providing a larger process margin.

It should be understood that when an element is referred to as being "connected" or "disposed" to another element, it can mean that the element is directly on the other element, or there may also be an intermediate element through which the element and another element are connected. Conversely, when an element is referred to as being “directly on another element” or “directly connected to another element”, it can be understood that at this time, it is clearly defined that there is no intermediate element.

In addition, the terms "first", "second", and "third" are only used to distinguish one element, component, region, or section from another element, component, region, layer or section, rather than indicating Its inevitable sequence. In addition, relative terms such as "under" and "upper" may be used herein to describe the relationship between one element and another element. It should be understood that relative terms are intended to include differences in devices other than the orientation shown in the figure. position. For example, if the device in one figure is turned over, elements described as being on the "lower" side of other elements will be oriented on the "upper" side of the other elements. This only represents a relative azimuth relationship, not an absolute azimuth relationship.

Fig. 1 is a top view of a first embodiment of a floating piezoelectric ultrasonic sensor. Fig. 2 is a cross-sectional view taken along line A-A of Fig. 1. As shown in FIGS. 1 and 2, the floating piezoelectric ultrasonic sensor 1 of the first embodiment includes a semiconductor substrate 10 and a piezoelectric ultrasonic sensor 20. The semiconductor substrate 10 includes a columnar arrangement area 11, a peripheral wall 13, and a bridge portion 15. A cavity 17 is formed between the columnar arrangement area 11 and the peripheral wall 13 and the cavity 17 surrounds the columnar arrangement area 11, and the bridge portion 15 is connected to the column. The area 11 and the peripheral wall 13 are arranged in a shape. The piezoelectric ultrasonic sensing element 20 is arranged on the columnar arrangement area 11.

More specifically, the cavity 17 between the columnar arrangement area 11 and the peripheral wall 13 can be completed by removing part of the semiconductor substrate 10 by laser or etching, so that the columnar arrangement area 11 appears in the cavity 17 The shape of an island in turn makes the piezoelectric ultrasonic sensing element 20 in a floating shape. In more detail, the width of the piezoelectric ultrasonic sensing element 20 is smaller than the columnar arrangement area 11. In the first embodiment, there is only one bridge portion 15 to connect the columnar arrangement area 11 and the peripheral wall 13. In this way, even if the internal cavity of the piezoelectric ultrasonic sensing element 20 is completed, the required resonant frequency can be adjusted by adjusting the length of the bridge portion 15. Generally speaking, the length of the bridging portion 15 is less than 1000 um, preferably 300 to 750 um. When the length of the bridge portion 15 is reduced, the resonance frequency can be increased, which in turn increases the emission angle. In this way, a wider process margin is provided. Furthermore, the resonant frequency is also a component that is judged to be defective, and the demand can be met through secondary processing, thus providing a solution for fine-tuning and correction.

Referring again to FIG. 2, the semiconductor substrate 10 further includes at least one through hole 19, which penetrates the semiconductor substrate 10 and communicates with the cavity 17. More specifically, the through hole 19 may be completed by a laser drilling technique, adjacent to the columnar arrangement area 11, to provide a path for removing part of the semiconductor substrate 10 afterwards to form the cavity 17.

In more detail, in some embodiments, the number of through holes 19 may be multiple, and the through holes 19 are distributed around the columnar arrangement area 11.

In order to achieve rapid through hole 19 and reduce the thermal damage of laser processing, the semiconductor substrate 10 can also be thinned before the through hole 19. Generally speaking, the thinning is done by etching, which has a lower cost. Cost, and faster efficiency. In addition, the thickness of the semiconductor substrate 10 also directly affects the sound pressure. The thickness of the semiconductor substrate 10 is reduced, and the sound pressure is thereby increased. Therefore, in addition to providing assistance in forming the through holes 19, the required performance can also be adjusted by controlling the thinning of the semiconductor substrate 10. Here, the thickness of the semiconductor substrate 10 is 200 to 700 um, preferably 300 to 600 um.

Fig. 3 is a top view of a second embodiment of a floating piezoelectric ultrasonic sensor. Fig. 4 is a top view of a third embodiment of a floating piezoelectric ultrasonic sensor. As shown in FIGS. 3 and 4, and referring to FIGS. 1 and 2, the suspension type piezoelectric ultrasonic sensor 1 of the second embodiment and the third embodiment differs from the first embodiment in that the bridge portion 15 quantity. The second embodiment has two bridges 15 and the third embodiment has four bridges 15. Each bridging portion 15 is connected to the columnar arrangement area 11 and the peripheral wall 13 respectively.

More specifically, in the third embodiment, the bridge portion 15 is more symmetrically located around the columnar arrangement area 11. This is only an example, and the number, position, and arrangement of the bridge portions 15 can be adjusted according to actual needs. More specifically, the total length of all bridge portions 15 is inversely proportional to the resonance frequency and the emission angle. The required resonance frequency and emission angle can also be adjusted by adjusting the number and total length of the bridge portions 15.

In summary, after the piezoelectric ultrasonic sensor element 20 is completed, a cavity 17 is further provided on the semiconductor substrate 10, and the columnar shape of the piezoelectric ultrasonic sensor element 20 is connected through the remaining bridge 15 The setting area 11 and the peripheral wall 13 can adjust the required resonant frequency in this way, and then adjust the required sound pressure and emission angle, so as to provide a larger process margin.

Although the technical content of this creation has been disclosed in a preferred embodiment as above, it is not intended to limit this creation. Anyone who is familiar with this technique, who does not deviate from the spirit of this creation, makes some changes and modifications, should be covered in this creation. Therefore, the scope of protection of this creation shall be subject to the scope of the attached patent application.

1: Suspended piezoelectric ultrasonic sensor 10: Semiconductor substrate 11: Columnar setting area 13: peripheral wall 15: Bridge 17: Cavity 19: Through hole 20: Piezoelectric ultrasonic sensing element

Fig. 1 is a top view of a first embodiment of a floating piezoelectric ultrasonic sensor. Fig. 2 is a cross-sectional view taken along line A-A of Fig. 1. Fig. 3 is a top view of a second embodiment of a floating piezoelectric ultrasonic sensor. Fig. 4 is a top view of a third embodiment of a floating piezoelectric ultrasonic sensor.

1: Suspended piezoelectric ultrasonic sensor

10: Semiconductor substrate

11: Columnar setting area

13: peripheral wall

15: Bridge

17: Cavity

20: Piezoelectric ultrasonic sensing element

Claims (9)

A floating piezoelectric ultrasonic sensor, including: A semiconductor substrate includes a columnar arrangement area, a peripheral wall, and at least one bridge portion, a cavity is formed between the columnar arrangement area and the peripheral wall, the cavity surrounds the columnar arrangement area, and the bridge portion is connected The columnar arrangement area and the peripheral wall; and A piezoelectric ultrasonic sensing element is arranged on the columnar arrangement area. The floating piezoelectric ultrasonic sensor according to claim 1, wherein the semiconductor substrate further includes at least one through hole, the through hole penetrates the semiconductor substrate and communicates with the cavity. The floating piezoelectric ultrasonic sensor according to claim 2, wherein the through hole is adjacent to the columnar arrangement area. The floating piezoelectric ultrasonic sensor according to claim 2, wherein the semiconductor substrate includes a plurality of through holes, the through holes penetrate the semiconductor substrate and are distributed around the columnar arrangement area, and the through holes The hole communicates with the cavity. The floating piezoelectric ultrasonic sensor according to claim 1, wherein the semiconductor substrate includes a plurality of bridge portions, and each bridge portion is respectively connected to the columnar arrangement area and the peripheral wall. The floating piezoelectric ultrasonic sensor according to claim 5, wherein the bridge portions are symmetrically located around the columnar arrangement area. The floating piezoelectric ultrasonic sensor according to claim 1, wherein the width of the piezoelectric ultrasonic sensor element is smaller than the columnar arrangement area. The floating piezoelectric ultrasonic sensor according to claim 1, wherein the thickness of the semiconductor substrate is 200 to 700 μm. The floating piezoelectric ultrasonic sensor according to claim 1, wherein the length of the bridge portion is less than 1000um.

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