JP2005051690A - Ultrasonic array sensor and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture an ultrasonic array sensor having the small fluctuation of resonant frequencies at a low cost. <P>SOLUTION: The ultrasonic array sensor 1 is provided with a base 10 in which the insulating layer 21 of an oxidized film is formed on an upper main surface 11a, and a plurality of recesses 12 each opening toward a lower main surface 11b and having an insulating layer 21 as the bottom are formed on the base 10. A lower electrode 31 contacting the insulating layer 21, a piezoelectric film 41, and an upper electrode 51 are provided in this order from the insulating layer 21 side on regions corresponding to the plurality of recesses 12 on the insulating layer 21 of the base 10 respectively, thereby configuring a vibration detecting layer 40 to form a diaphragm having a uniform thickness. In this way, the ultrasonic array sensor 1 having the small fluctuation of resonant frequencies for each sensor element can be manufactured at a low cost by using a silicon substrate 11. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ultrasonic array sensor in which a plurality of sensor elements for detecting ultrasonic waves are arranged.

  An ultrasonic array in which a plurality of sensor elements are arranged to detect a reflected wave from a transmitted ultrasonic wave object using a resonance phenomenon in order to specify the distance to the object and the direction in which the object is located. The practical application of sensors has been promoted in recent years.

1 and 2 are views showing a state in which a conventional ultrasonic array sensor 9 (see FIG. 2) is manufactured. When manufacturing the conventional ultrasonic array sensor 9, first, an SOI (Silicon On Insulator) substrate 91 shown in FIG. 1 is prepared. The SOI substrate 91 includes a base layer 911 formed of silicon (Si), a box layer 912 formed of silicon oxide (SiO ₂ ), and an active layer 913 formed of silicon. As shown in FIG. 2, an insulating layer 92 is formed on the upper main surface 91a of the SOI substrate 91. In a plurality of predetermined regions (regions where sensor elements are formed) on the insulating layer 92, lower electrodes 931, A vibration detection layer 93 including the piezoelectric film 932 and the upper electrode 933 is formed (however, only one sensor element 90 is shown in FIG. 2).

  Subsequently, a plurality of recesses 910 are formed by etching the lower main surface 91 b of the SOI substrate 91. At this time, since the box layer 912 is hardly etched, it serves as an etching stop layer that stops the progress of the etching, and the concave portion 910 is accurately formed in the depth direction (that is, the base layer 911 is etched by its thickness). Etching variation is prevented.)

  In the ultrasonic array sensor 9 manufactured in this manner, the bottom portion of each recess 910 forms a diaphragm portion, and the diaphragm portion receives and resonates with ultrasonic waves of its own resonance frequency, so that the electrodes 931 and 933 are resonated. A potential difference is generated between them, and an electric signal is output.

Non-Patent Document 1 discloses the structure and manufacturing process of an ultrasonic array sensor using a PZT (lead zirconate titanate) thin film formed by a sol-gel method as a piezoelectric film.
Katata and 6 others, "Array-type ultrasonic microsensor using PZT thin film", Study Group Material, Physical Sensor Study Group, December 20, 2000, PHS-00-21, p. 219-222

  In general, an SOI substrate is formed by oxidizing the surface of a substrate formed of silicon (hereinafter referred to as a “silicon substrate”), and bonding another silicon substrate thereon, and then polishing one silicon substrate to make it thin. It is produced by doing. However, since the thickness of the active layer in the SOI substrate (or between the substrates) varies due to processing variations, the thickness of the diaphragm portion of the manufactured ultrasonic array sensor also varies. As a result, a difference occurs in the resonance frequency of the diaphragm portion between sensor elements (or between ultrasonic array sensors), and ultrasonic waves may not be detected accurately.

  Moreover, since the SOI substrate is more expensive than a general substrate (for example, about 10 times the price of a silicon substrate), the manufacturing cost of the ultrasonic array sensor is also increased.

  The present invention has been made in view of the above problems, and an object of the present invention is to manufacture an ultrasonic array sensor with a small variation in resonance frequency at low cost.

  The invention according to claim 1 is a method of manufacturing an ultrasonic array sensor in which a plurality of sensor elements for detecting ultrasonic waves are arranged, and a) an etching stop having insulation on one main surface of a silicon substrate. Forming a layer; b) forming a lower electrode, a piezoelectric film and an upper electrode in order from the etching stop layer side in at least a plurality of element formation regions on the etching stop layer; c) Forming a plurality of recesses by performing etching up to the etching stop layer in a plurality of regions on the other main surface of the silicon substrate corresponding to the element formation region.

  The invention according to claim 2 is the method of manufacturing the ultrasonic array sensor according to claim 1, wherein in the step a), an oxide film formed by thermal oxidation is etched on the one main surface of the silicon substrate. A step of forming an additional oxide film on the oxide film is further provided between the step a) and the step b).

  A third aspect of the present invention is the method of manufacturing the ultrasonic array sensor according to the first aspect, wherein in the step a), a nitride film is formed as the etching stop layer on the one main surface of the silicon substrate. In step c), etching is performed with an aqueous potassium hydroxide solution.

  The invention according to claim 4 is the method for manufacturing the ultrasonic array sensor according to claim 1, wherein a polysilicon layer is formed on the etching stop layer between the step a) and the step b). And a step of forming an insulating layer on the polysilicon layer.

  The invention according to claim 5 is an ultrasonic array sensor in which a plurality of sensor elements for detecting ultrasonic waves are arranged, wherein an insulating layer of an oxide film or a nitride film is formed on one main surface of a silicon substrate. A base portion having a plurality of recesses opening toward another main surface and having the insulating layer as a bottom, and at least a region on the insulating layer corresponding to the plurality of recesses from the insulating layer; A vibration detection layer having a lower electrode, a piezoelectric film, and an upper electrode in contact with the insulating layer is sequentially provided.

  The invention according to claim 6 is an ultrasonic array sensor in which a plurality of sensor elements for detecting ultrasonic waves are arranged, and an oxide film or a nitride film insulating layer is formed on one main surface of a silicon substrate. A base portion having a plurality of recesses opening toward another main surface and having the insulating layer as a bottom portion; a polysilicon layer formed on the insulating layer in order from the insulating layer side; and another one And a vibration detection layer having a lower electrode, a piezoelectric film, and an upper electrode in that order from the other insulating layer in a region corresponding to at least the plurality of recesses on the other insulating layer.

  According to the present invention, an ultrasonic array sensor having a small variation in resonance frequency can be manufactured at low cost using a silicon substrate.

  In the inventions of claims 2, 4 and 6, the environmental resistance of the ultrasonic array sensor can be increased.

  FIG. 3 is a longitudinal sectional view showing the ultrasonic array sensor 1 according to the first embodiment of the present invention. The ultrasonic array sensor 1 includes a plurality of sensor elements that detect ultrasonic waves. FIG. 3 shows only one sensor element 100. Actually, a plurality of sensor elements 100 are arranged in the left-right direction and the direction perpendicular to the paper surface. Further, in FIG. 3, for convenience of illustration, the thin film portion is shown with a strong emphasis.

The ultrasonic array sensor 1 shown in FIG. 3 is a layer formed of an insulating layer 21 (for example, silicon oxide (SiO ₂ )) of an oxide film on the upper main surface 11 a of the silicon substrate 11. 21 ”.) Is provided. The base portion 10 is a substrate on which is formed. However, in the following description, the oxide film formed on the lower main surface is also referred to as the base portion 10. The base 10 has a plurality of recesses 12 (for example, recesses having a trapezoidal cross-sectional shape with an upper base of 350 μm and a lower base of 700 μm) that open toward the lower main surface 11b and have the insulating layer 21 as a bottom. It is formed. One recess 12 corresponds to one sensor element 100, and only one recess 12 is shown in FIG.

  The regions corresponding to the plurality of recesses 12 on the insulating layer 21 of the base portion 10 (that is, the regions directly above the plurality of recesses 12) are mainly formed of platinum (Pt) in this order from the insulating layer 21 side. A lower electrode 31 in contact with the insulating layer 21 (precisely, a layer formed of titanium (Ti) and a layer formed of platinum are laminated from the insulating layer 21 side), a piezoelectric formed of PZT. A film 41 and an upper electrode 51 formed of platinum are provided, and the vibration detection layer 40 that detects vibration as a voltage is configured by the lower electrode 31, the piezoelectric film 41, and the upper electrode 51. The lower electrode 31 is preferably platinum from the viewpoint of forming a PZT film with orientation, and it is confirmed that the lower electrode 31 is preferably platinum even when the piezoelectric film 41 is formed of ZnO (zinc oxide). Yes. When the piezoelectric film 41 is a resin such as PVDF (polyvinylidene fluoride), the lower electrode 31 does not need to be platinum. The upper electrode 51 is not necessarily formed of platinum, and may be formed of another conductor such as gold or aluminum.

  In the ultrasonic array sensor 1, the portions of the upper insulating layer 21, the lower electrode 31, the piezoelectric film 41, and the upper electrode 51 receive ultrasonic waves from the bottom surface (that is, the surface formed by the insulating layer 21) of each recess 12. It is a thin diaphragm that vibrates.

  The ultrasonic array sensor 1 is used together with a sound source device that transmits ultrasonic waves of a predetermined frequency. For example, a 100 kHz ultrasonic wave is transmitted from the sound source device to the ultrasonic array sensor 1 having a resonance frequency of 100 kHz for each diaphragm part, and each diaphragm part resonates by receiving a reflected wave from an object. An electrical signal is output from the element 100. Then, by analyzing the plurality of output signals, the distance to the object and the direction in which the object is located are specified.

  Next, a method for manufacturing the above-described ultrasonic array sensor 1 will be described. FIG. 4 is a diagram showing the flow of the manufacturing process of the ultrasonic array sensor 1.

  When the ultrasonic array sensor 1 is manufactured, first, a silicon substrate 11 shown in FIG. 5 is prepared. The silicon substrate 11 shown in FIG. 5 has a thickness of several hundred μm, and heat treatment such as annealing (for example, heat treatment up to 1200 degrees in an oxygen atmosphere) oxidizes both main surfaces 11a and 11c, As shown in FIG. 6, oxide films 21 and 22 made of silicon oxide are formed with a uniform thickness (for example, about 1 μm), respectively (step S11). The oxide film 22 on the main surface 11c side may be formed only if necessary.

  Subsequently, a lower electrode 31 (and a necessary wiring pattern) is formed on the oxide film (insulating layer) 21 on the main surface 11a (hereinafter also referred to as “upper surface 11a”) side as shown in FIG. Step S12). When the lower electrode 31 is formed, first, a titanium (Ti) film is formed on the insulating layer 21 by sputtering, and a platinum film is formed on the titanium film. Since the titanium film serves as an intermediate layer for improving the adhesion of the platinum film, hereinafter, the titanium film and the platinum film are simply referred to as a platinum film.

  FIG. 8 is a plan view illustrating a part of the silicon substrate 11 on which the platinum film is formed. A photoresist pattern is formed on the platinum film using photolithography. That is, a photoresist is applied on the platinum film, a predetermined pattern is drawn on the photoresist by a stepper or the like, and then development is performed to form a photoresist pattern. Then, the platinum film is etched (milled) by an ion milling device or the like, and the photoresist is removed from the silicon substrate 11, whereby the lower electrode 31 is formed.

  FIG. 9 is a plan view illustrating a part of the silicon substrate 11 on which the lower electrode 31 is formed. In FIG. 9, a plurality of lower electrodes 31 arranged in a cross shape are formed on the silicon substrate 11. Each of the plurality of lower electrodes 31 communicates with a connection electrode 33 that is disposed at a distant position via a wiring 32. In FIG. 9, a rectangular area 71 indicated by a two-dot chain line including each of the plurality of lower electrodes 31 is a formation area of one sensor element (hereinafter referred to as “element formation area”) manufactured through the following steps. Yes, on the back surface side, it becomes a region where the recess 12 shown in FIG. Note that the longitudinal sectional view referred to in this embodiment is simplified and therefore does not correspond exactly to the plan view of FIG.

  When the lower electrode 31 shown in FIG. 7 is formed, a piezoelectric film 41 made of a piezoelectric material is formed on the lower electrode 31 as shown in FIG. 10 (step S13). Specifically, first, a PZT film is formed on the entire surface of the silicon substrate 11 by a sol-gel method. At this time, since the platinum film forming the lower electrode 31 has good orientation, a PZT film having high orientation is obtained at least on the lower electrode 31. Subsequently, a photoresist pattern is formed on the PZT film using photolithography, and wet etching is performed to remove a portion of the PZT film not covered with the photoresist. Then, the photoresist is removed from the silicon substrate 11, and the formation of the piezoelectric film 41 is completed.

  FIG. 11 is a plan view illustrating a part of the silicon substrate 11 on which the piezoelectric film 41 is formed, and corresponds to FIG. Further, in FIG. 11, a rectangular region 72 (which is finally a diaphragm portion of the sensor element 100) occupied by the lower electrode 31 of FIG. 9 is indicated by a broken line. As shown in FIG. 11, the piezoelectric film 41 is formed so as to cover all the element formation regions 71, and the piezoelectric film 41 is provided with a plurality of through holes 42 that are respectively continuous with the plurality of connection electrodes 33. .

  Subsequently, the upper electrode 51 is formed on the piezoelectric film 41 of FIG. 10 as shown in FIG. 12 (step S14). In the same manner as the lower electrode 31 in step S12, the upper electrode 51 is formed by depositing platinum on the entire surface by sputtering, drawing a predetermined pattern on the photoresist applied on the platinum film, and developing the photoresist. A pattern is formed. After the milling, the photoresist is removed from the silicon substrate 11 to form the upper electrode 51, and the vibration detection layer 40 including the lower electrode 31, the piezoelectric film 41, and the upper electrode 51 has a predetermined thickness. Uniformly formed.

  FIG. 13 is a plan view illustrating a part of the silicon substrate 11 on which the upper electrode 51 is formed, and corresponds to FIGS. 9 and 11. As shown in FIG. 13, a plurality of upper electrodes 51 are formed on the piezoelectric film 41 and arranged in a cross shape and located in regions 72 on the lower electrodes 31 in the plurality of element formation regions 71, respectively. The plurality of upper electrodes 51 communicate with one connection electrode 53 through a cross-shaped wiring 52. The upper electrode 51 (and the wiring 52 and the connection electrode 53) may also be provided with a titanium film as an intermediate layer, like the lower electrode 31.

  When the upper electrode 51 shown in FIG. 12 is formed, a photo is formed on the lower main surface 11b (referred to as the surface of the oxide film 22, hereinafter also referred to as “lower surface 11b”) of the silicon substrate 11 after the oxide film is formed. By forming a resist pattern and performing etching (for example, wet etching using hydrofluoric acid), a part of the oxide film 22 is formed in a plurality of regions corresponding to the plurality of element formation regions 71 on the lower surface 11b. Removed.

  Subsequently, anisotropic etching is performed on the silicon substrate 11 up to the insulating layer 21 using TMAH (Tetramethylammonium Hydroxide) using the oxide film 22 as an etching mask, thereby forming the lower surface 11b as shown in FIG. A plurality of recesses 12 opening toward the bottom and having the insulating layer 21 as a bottom are formed, and a diaphragm portion is formed (step S15). At this time, since the insulating layer 21 is hardly etched by TMAH, the insulating layer 21 serves as an etching stop layer that stops the progress of etching, and the concave portion 12 is accurately formed in the depth direction and the diaphragm portion formed by film formation. Becomes a uniform thickness (for example, several μm). Further, the substrate in which the insulating layer 21 is formed on the silicon substrate 11 becomes the base portion 10 in FIG.

  Then, the silicon substrate 11 is divided into dies having the size shown in FIG. 13 as a unit, and the ultrasonic array sensor 1 shown in FIG. 3 is completed. The ultrasonic array sensor 1 is attached on, for example, a predetermined circuit board. A plurality of connection electrodes 33 and 53 (see FIG. 13) are connected to electrodes on the circuit board through wire bonding by wire bonding, and are used for ultrasonic detection. Potting is appropriately performed on the connection electrodes 33 and 53.

  As described above, in the ultrasonic array sensor 1 shown in FIG. 3, the etching stop layer having insulation is formed on the upper surface 11a of the silicon substrate 11, the vibration detection layer 40 is provided on the etching stop layer, and the silicon substrate 11 is etched from the lower surface 11b (main surface 11c in FIG. 5 when the oxide film 22 is not present) to the etching stop layer, so that a diaphragm portion having a uniform thickness is formed. Thereby, the dispersion | variation in the resonant frequency in the several sensor element 100 of the ultrasonic array sensor 1 can be suppressed small. Moreover, the manufacturing cost of the ultrasonic array sensor 1 can be reduced by using the silicon substrate 11 which is cheaper than the SOI substrate. If the lower electrode 31, the piezoelectric film 41, and the upper electrode 51 are formed in a region (or a part of the region) corresponding to at least the plurality of recesses 12 on the insulating layer 21, other regions are used. It may spread arbitrarily.

  In step S11, a nitride film (that is, silicon nitride) may be formed on the upper surface 11a of the silicon substrate 11 as the insulating layer 21 as an etching stop layer. The nitride film is formed by, for example, a CVD method (Chemical Vapor Deposition). ) To form a film. In this case, in step S15, the recess 12 can be formed by using a potassium hydroxide (KOH) aqueous solution as an etchant in addition to TMAH. The surface state of the recess 12 of the silicon substrate 11 etched with the potassium hydroxide aqueous solution is generally of good quality. Note that the etchant used for anisotropic etching is not necessarily TMAH or a potassium hydroxide aqueous solution, and is appropriately determined according to the type of the insulating layer.

  Further, the recess 12 is not necessarily formed by wet etching, and if the etching rate of the insulating layer 21 is extremely lower than that of the silicon substrate 11 (that is, if the insulating layer 21 serves as an etching stop layer). It is also possible to use other etching methods such as dry etching.

  FIG. 14 is a longitudinal sectional view showing an ultrasonic array sensor 1a according to another example, and shows only one sensor element 100. FIG. In the ultrasonic array sensor 1a of FIG. 14, the thickness of the insulating layer 21a is greatly different from that of the ultrasonic array sensor 1 of FIG. The insulating layer 21a is composed of an oxide film formed by thermal oxidation on the silicon substrate 11 and an oxide film additionally formed by a CVD method. The other configuration is the same as in FIG. 3, the vibration detection layer 40 including the lower electrode 31, the piezoelectric film 41, and the upper electrode 51 is formed on the insulating layer 21 a, and the insulating layer 21 a is formed on the silicon substrate 11. A concave portion 12 that opens toward the lower main surface 11b is formed in the base portion 10 that is a substrate.

  FIG. 15 is a diagram showing a flow of a manufacturing process of the ultrasonic array sensor 1a, and shows a process performed between step S11 and step S12 of FIG.

  When the ultrasonic array sensor 1a shown in FIG. 14 is manufactured, the oxide films 21 and 22 are formed by thermal oxidation on both main surfaces 11a and 11c of the silicon substrate 11 as in the ultrasonic array sensor 1 of FIG. (See FIG. 6) (FIG. 4: Step S11) An oxide film (for example, silicon oxide) is additionally formed on the oxide film 21 (insulating layer) with a uniform thickness by the CVD method (Step S21). Thereby, as shown in FIG. 16, an insulating layer 21a in which the oxide film 21 is further thickened is formed. Thereafter, through steps similar to those shown in FIGS. 7 to 13, the lower electrode 31, the piezoelectric film 41, and the upper electrode 51 are formed in a predetermined region on the insulating layer 21a (FIG. 4: steps S12 to S14). ).

  Further, on the oxide film 22 on the lower surface 11b side, a photoresist pattern is formed in which only a region for forming a recess is exposed corresponding to the element formation region 71 (see FIG. 13), and a part of the oxide film 22 is formed. By removing and performing anisotropic etching by wet etching, as shown in FIG. 14, a plurality of recesses 12 opening toward the main surface 11b on the lower oxide film 22 side of the silicon substrate 11 are formed. (That is, a diaphragm portion is formed) (step S15). At this time, the oxide film formed by thermal oxidation, which is a lower layer in the insulating layer 21a, substantially serves as an etching stop layer, and has a relatively high strength and a uniform thickness. An ultrasonic array sensor 1a having a portion is completed.

  As described above, in the ultrasonic array sensor 1a of FIG. 14, an oxide film is further formed on the oxide film 21 formed on the silicon substrate 11 to form a relatively thick insulating layer 21a. Thereby, the intensity | strength of a diaphragm part can be increased, making the thickness of a diaphragm part uniform. As a result, the ultrasonic array sensor 1a having high environmental resistance and small variations in resonance frequency can be manufactured at low cost. The oxide film additionally formed on the oxide film 21 is not necessarily formed by the CVD method, and may be formed by another method such as a PVD method (Physical Vapor Deposition), for example.

  FIG. 17 is a longitudinal sectional view showing the ultrasonic array sensor 1 b according to the second embodiment, and shows only one sensor element 100. In the ultrasonic array sensor 1b of FIG. 17, a layer (hereinafter referred to as “polysilicon layer”) formed of polysilicon (Poly Silicon) in order from the insulating layer 21 side between the insulating layer 21 and the vibration detection layer 40. ) 23 and another insulating layer 24 formed of silicon oxide is provided, which is different from the ultrasonic array sensor 1 of FIG. Other configurations are the same as those in FIG. 3, and are denoted by the same reference numerals.

  FIG. 18 is a diagram showing the flow of the manufacturing process of the ultrasonic array sensor 1b, and shows the process performed between step S11 and step S12 of FIG.

  When oxide films 21 and 22 are formed on both main surfaces 11a and 11c of the silicon substrate 11 as in the ultrasonic array sensor 1 of FIG. 3 (see FIG. 6) (FIG. 4: step S11), it is shown in FIG. Thus, a polysilicon layer 23 is formed on the oxide film 21 (insulating layer) by, for example, the CVD method (step S31), and then an insulating layer 24 (for example, oxidized) formed on the polysilicon layer 23 by the CVD method. Film) is provided (step S32). Note that the polysilicon layer 23 and the insulating layer 24 may be formed by a method other than the CVD method as long as they are formed with a uniform thickness.

  In a predetermined region on the insulating layer 24, the vibration detection layer 40 is formed by laminating the lower electrode 31, the piezoelectric film 41, and the upper electrode 51 in this order from the insulating layer 24 side in the same manner as in the first embodiment. (FIG. 4: Steps S12 to 14). Then, anisotropic etching is performed up to the oxide film 21 in regions on the oxide film 22 on the lower surface side facing the plurality of element formation regions 71 (see FIG. 13), as shown in FIG. A plurality of recesses 12 having openings toward the lower surface 11b and having the oxide film 21 as a bottom are formed (that is, a diaphragm portion is formed), and the ultrasonic array sensor 1b is completed (step S15).

  As described above, in the ultrasonic array sensor 1b of FIG. 17, the polysilicon layer 23 and the other insulating layer 24 are formed on the insulating layer 21 of the base portion 10 formed by the silicon substrate 11 having the plurality of recesses 12. Thus, the strength of the diaphragm portion can be easily increased while keeping the thickness uniform. Thereby, the ultrasonic array sensor 1b having high environmental resistance and small variation in the resonance frequency can be manufactured at low cost.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made.

  Also in the ultrasonic array sensors 1a and 1b shown in FIGS. 14 and 17, the insulating layer 21 may be formed of a nitride film as in the ultrasonic array sensor 1 of FIG. The nitride film may be formed by a method other than the CVD method.

  The insulating layer 21 may be an insulator other than an oxide film and a nitride film as long as it functions as an etching stop layer that suppresses the progress of etching when the recess 12 is formed. That is, the material for forming the etching stop layer may be appropriately determined according to the type of etching method.

  In the ultrasonic array sensor, the sensor elements may be arranged in a shape other than a cross shape, and in order to form a highly accurate ultrasonic array sensor, the sensor elements are preferably arranged in a matrix.

  In the above embodiment, the plurality of upper electrodes 51 are electrically connected and the lower electrode 31 is provided independently. However, the plurality of lower electrodes 31 may be connected and the upper electrodes 51 may be independent of each other. Moreover, each of the upper electrode 51 and the lower electrode 31 may be provided independently of each other. The piezoelectric film 41 may also be provided independently for each element formation region 71. Note that the element formation region 71 and the recess 12 do not need to correspond exactly, and each element formation region 71 merely defines a region that roughly corresponds to each sensor element 100.

  The flow of the process for manufacturing the ultrasonic array sensor may be appropriately changed within a possible range.

It is a figure which shows an SOI substrate. It is sectional drawing which shows the conventional ultrasonic array sensor. It is sectional drawing which shows the ultrasonic array sensor which concerns on 1st Embodiment. It is a figure which shows the flow of the manufacturing process of an ultrasonic array sensor. It is a figure which shows the mode of manufacture of an ultrasonic array sensor. It is a figure which shows the mode of manufacture of an ultrasonic array sensor. It is a figure which shows the mode of manufacture of an ultrasonic array sensor. It is a figure which shows the mode of manufacture of an ultrasonic array sensor. It is a figure which shows the mode of manufacture of an ultrasonic array sensor. It is a figure which shows the mode of manufacture of an ultrasonic array sensor. It is a figure which shows the mode of manufacture of an ultrasonic array sensor. It is a figure which shows the mode of manufacture of an ultrasonic array sensor. It is a figure which shows the mode of manufacture of an ultrasonic array sensor. It is sectional drawing which shows the other example of an ultrasonic array sensor. It is a figure which shows the flow of the manufacturing process of an ultrasonic array sensor. It is a figure which shows the mode of manufacture of an ultrasonic array sensor. It is sectional drawing which shows the ultrasonic array sensor which concerns on 2nd Embodiment. It is a figure which shows the flow of the manufacturing process of an ultrasonic array sensor. It is a figure which shows the mode of manufacture of an ultrasonic array sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1a, 1b Ultrasonic array sensor 10 Base part 11 Silicon substrate 11a-11c Main surface 12 Recessed part 21,21a, 24 Insulating layer 23 Polysilicon layer 31 Lower electrode 40 Vibration detection layer 41 Piezoelectric film 51 Upper electrode 71 Element formation area 100 sensor elements S11-S15, S21, S31, S32 step

Claims (6)

A method of manufacturing an ultrasonic array sensor in which a plurality of sensor elements for detecting ultrasonic waves are arranged,
a) forming an insulating etch stop layer on one main surface of the silicon substrate;
b) forming a lower electrode, a piezoelectric film and an upper electrode in order from the etching stop layer side in at least a plurality of element formation regions on the etching stop layer;
c) forming a plurality of recesses by performing etching until reaching the etching stop layer in a plurality of regions on the other main surface of the silicon substrate corresponding to the plurality of element formation regions;
A method for manufacturing an ultrasonic array sensor, comprising: It is a manufacturing method of the ultrasonic array sensor according to claim 1,
In the step a), an oxide film by thermal oxidation is formed on the one main surface of the silicon substrate as the etching stop layer,
A method for manufacturing an ultrasonic array sensor, further comprising a step of additionally forming an oxide film on the oxide film between the step a) and the step b). It is a manufacturing method of the ultrasonic array sensor according to claim 1,
In the step a), a nitride film is formed as the etching stop layer on the one main surface of the silicon substrate,
In the step c), the ultrasonic array sensor manufacturing method is characterized in that etching is performed with an aqueous potassium hydroxide solution. It is a manufacturing method of the ultrasonic array sensor according to claim 1,
Between step a) and step b)
Forming a polysilicon layer on the etch stop layer;
Forming an insulating layer on the polysilicon layer;
An ultrasonic array sensor manufacturing method, further comprising: An ultrasonic array sensor in which a plurality of sensor elements for detecting ultrasonic waves are arranged,
A substrate having an insulating layer of an oxide film or a nitride film formed on one main surface of a silicon substrate, a base portion having a plurality of recesses opening toward the other main surface and having the insulating layer as a bottom,
In a region corresponding to at least the plurality of recesses on the insulating layer, in order from the insulating layer, a vibration detection layer having a lower electrode, a piezoelectric film, and an upper electrode in contact with the insulating layer;
An ultrasonic array sensor comprising: An ultrasonic array sensor in which a plurality of sensor elements for detecting ultrasonic waves are arranged,
A substrate having an insulating layer of an oxide film or a nitride film formed on one main surface of a silicon substrate, a base portion having a plurality of recesses opening toward the other main surface and having the insulating layer as a bottom,
A polysilicon layer and another insulating layer sequentially formed on the insulating layer from the insulating layer side;
A vibration detection layer having a lower electrode, a piezoelectric film, and an upper electrode in order from the other insulating layer in a region corresponding to at least the plurality of recesses on the other insulating layer;
An ultrasonic array sensor comprising:

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