JPS61220600A - Ultrasonic wave sensor - Google Patents

Abstract

PURPOSE:To obtain easily an arraying by providing a signal input electrode facing an electrode which is so processed that a metal is evaporated on a high polymer film on the recessed part of an N-typed silicon substrate and providing a signal terminal on a P-typed silicon that pierces the N-typed silicon substrate. CONSTITUTION:A signal input electrode 4 is provided on the base of a recessed part that is provided on an N-typed silicon 1 through an insulator 3. A diaphragm that a metallic electrode 6 is evaporated on a high polymer film 5 is installed as to cover the recessed part of the silicon 1. The signal electrode 4 and a signal terminal 7 are connected to a P<+> typed silicon 2 that is provided to pierce the N-typed silicon 1. Thus, an easy assembling and the arraying are obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an ultrasonic sensor and relates to a bamboo capacitor type ultrasonic sensor.

(Prior art and vanishing point) -S, a capacitor type ultrasonic sensor is known as a type of ultrasonic sensor. This sensor is mainly used as a distance measurement sensor, and is formed by a polymer film with a metal electrode on its surface and a (2) pole placed a certain distance apart from the polymer film. .

Conventionally, the capacitor type ultrasonic sensor mentioned above is mainly used for distance measurement, and it is useful to measure the delay time until the ultrasonic wave sent out from the surface of the sensor bounces off an object in front and returns to the sensor. The distance between the sensor and the object to the east can be calculated from the calculation formula %.

As this distance measuring ultrasonic sensor, Polaroid's automatic 4
A condenser type ultrasonic sensor used in a B< point camera is well known. This ultrasonic sensor manufactured by Polaroid has a structure in which a polymer film with thin metal electrodes is pressed onto the surface of an aluminum disk with concentric grooves. The front surface of the polymer film and the back surface of the aluminum each serve as electrodes and are easily electrically connected to the outside. In this way, the capacitor type ultrasonic sensor is characterized by a simple structure.

However, when performing ultrasonic imaging in which multiple capacitor-type ultrasonic sensors are arranged in an array and the relative phase of the ultrasonic waves sent out from each sensor is changed to scan the ultrasonic waves, conventional capacitor-type ultrasonic The sensor was difficult to use. That is, in an ultrasonic scanning sensor array, the width of each ultrasonic sensor forming the array must be made as small as the wavelength of the ultrasonic waves used. For example, the wavelength of ultrasonic waves with a frequency of 100 kHz in air is approximately 34 mm, and it is said that making conventional capacitor-type ultrasonic sensors as large as the wavelength and arranging them in an array would require a significant increase in the assembly process. A shortcoming occurred.

(Object of the Invention) An object of the present invention is to eliminate such conventional drawbacks and provide a capacitor-type ultrasonic sensor suitable for sensor array formation.

(Structure of the Invention) According to the present invention, a thin metal electrode is composed of a polymer film on the surface of which is provided, and a signal input electrode is installed at a certain distance from the polymer film, and an alternating current voltage applied between the electrodes is used. This polymer film vibrates and generates ultrasonic waves, and when the ultrasonic waves are incident on this polymer film, the capacitance between the electrodes changes and the ultrasonic waves are detected.In the sensor, the signal input electrode is made of n-type silicon. A polymer film is provided in a recess formed on one side of the substrate and has the thin metal electrode on its surface, and is provided to cover the recess, and this signal input electrode penetrates the n-type silicon substrate. A one-person ultrasonic sensor is obtained, characterized in that the V-shaped layer is taken out on the other side.

(Example) The present invention will be described below with reference to drawings showing examples. FIG. 1 is a sectional view showing one embodiment of the present invention. In the same figure, 1 is an n-type silicon substrate, 2 is a P+ type silicon substrate, and 3 is a cross-sectional view showing an embodiment of the present invention.
is an insulator, 4 is a signal input electrode, 5 is a polymer film such as polyester, 6 is a metal electrode such as gold, 7 is a signal terminal,
8 is a ground terminal, and 9 is n+ type silicon. The signal input electrode 4 is provided in a region anisotropically etched from the back side of an n-type silicon wafer with an insulator 3 interposed therebetween. Generally, when silicon is anisotropically etched with a potassium hydroxide (KOH) solution or hydrazine solution using a silicon oxide (Sin) film or a silicon nitride film as a mask, the dimensional accuracy of the etched area is less than that of isotropic etching. We were able to obtain an array with higher uniformity of characteristics compared to the conventional method. Further, the signal input electrode 4 is connected to the signal terminal 7 on the silicon surface via the l)+ type silicon 2.

This type of silicon is produced by forming aluminum (A7) with a thickness of approximately 5 μm in a predetermined shape on the surface of the silicon, and then heating the back surface of the silicon with light irradiation, which causes the aluminum to move through the silicon (Anthony (T, R, A, nthony).

Klein (H, E, CI tne); Journal of Applied Fixtures (J, Appl, phys.
), vo147゜no, 6. p, 2316. (197
6)) can be easily formed.

(Effect of the invention) Since the upper and lower surfaces of the silicon substrate 1 having a thickness of 100 μm to 500 μm are electrically connected in this way, the signal input electrode 4, which is one electrode of the capacitor type ultrasonic sensor, It is taken out to the silicon surface by a signal terminal 7 provided on the silicon surface, and a metal electrode 6 is provided on the back surface of the silicon.
It is only necessary to form a polymer film 5 provided with
It was also easy to assemble. When arrayed, each signal terminal has an insulator 3, me-type silicon 2, and n-type silicon 1.
They are electrically isolated by a P-n junction.

The n+ type silicon 9 and the ground terminal 8 are for grounding the n type silicon 1. FIG. 2 is a plan view of FIG. 1, showing how signal terminals 7 and ground terminals 8 are provided on the silicon surface. From the same figure, most of the silicon surface area is
For example, it can be used to form air sentry circuits such as drive circuits and reception signal circuits for ultrasonic sensors.

FIG. 3 is a sectional view of an array of the ultrasonic sensors shown in FIG. 1, which is an embodiment of the present invention. A plurality of capacitor-type ultrasonic sensors are formed in an array within a silicon wafer, and these can be manufactured with high precision by using photolithography technology in silicon IC manufacturing technology.

In addition to a -dimensional array, the present invention also allows ultrasonic sensors to be arranged two-dimensionally within a silicon plane.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of one embodiment of the present invention, and FIG.
The plan view and FIG. 3 are cross-sectional views of an embodiment in which capacitor-type ultrasonic sensors according to the present invention are arranged in an array. In the figure, 1 is n-type silicon, 2 is P+m silicon,
3 is an insulator, 4 is a signal input electrode, 5 is a polymer film,
6 is a metal electrode, 7 is a signal terminal, 8 is a ground terminal, 9 is n
+ indicates silicon. Agent: Mr. Susumu 5. .

Claims (1)

[Claims] It consists of a polymer film with a thin metal electrode on its surface and a signal input electrode placed a certain distance away from the polymer film, and an alternating current voltage applied between the electrodes causes this polymer film to vibrate and generate ultrasonic waves. In addition, in an ultrasonic sensor that detects ultrasonic waves by changing the capacitance between the electrodes when ultrasonic waves are incident on the polymer film, the signal input electrode is formed on one surface of an n-type silicon substrate. A polymer film is provided in the recess and has the thin metal electrode on its surface, and is provided to cover the recess, and the signal input electrode is connected to the other side by a P^+ type layer penetrating the n-type silicon substrate. An ultrasonic sensor characterized by being taken out on the surface of.