KR102536838B1 - The Capacitive Micromachined Ultrasonic Transducer Device and the Fabrication Method Of The Same - Google Patents

Abstract

A method of manufacturing a capacitive ultrasonic transducer element according to an embodiment of the present invention includes a silicon element substrate; a single crystal silicon membrane disposed on the silicon element substrate; an upper electrode disposed on the single crystal silicon membrane; and a first electrode pad and a second electrode pad disposed on a lower surface of the silicon element substrate. The silicon device substrate may include a plurality of active regions arranged in a matrix form on the silicon device substrate and operating as electrodes; a trench glass layer buried in the silicon device substrate to separate the active regions from each other; a through trench glass layer disposed to surround the trench glass layer and disposed to pass through the silicon device substrate; and a peripheral area disposed to surround the through trench glass layer.

Description

The Capacitive Micromachined Ultrasonic Transducer Device and the Fabrication Method Of The Same}

The present invention relates to a capacitive ultrasonic transducer element using a semiconductor process technology and a manufacturing method thereof, and more particularly to a capacitive ultrasonic transducer element employing an anodic bonding and a double trench structure.

Ultrasonic transducers by the existing ceramic processing method are manufactured by mechanical processing (dicing) of piezoelectric materials, and mass production is difficult, causing a rise in product prices.

Ultrasonic transducers by existing ceramic processing methods are being replaced by capacitive micromachined ultrasonic transducers (cMUT).

Capacitive ultrasonic transducers can be manufactured with semiconductor process-based technology to improve mass production and reliability. cMUT has a lower sound pressure threshold compared to ultrasonic transducers manufactured by conventional ceramic processing methods, so it is common to configure a plurality of cMUT cells in one channel.

cMUT can be unified with a signal processing chip by using a semiconductor process. The cMUT may form a vacuum cavity through wafer fusion bonding or wafer direct bonding.

Wafer fusion bonding depends on the flatness, smoothness, and cleanliness of the surfaces of two wafers. In particular, when the cleaning degree is low, the bonding process failure rate is high.

It is essential to use a 2-D array to electrically steer ultrasonic waves, and for this, electrical signals must be connected to electrodes in each channel. To fabricate 2-D arrays, cMUTs typically use a through silicon via (TSV) process. Each channel includes a plurality of cavity cells to generate high power.

Therefore, a new process and a new structure are required to increase area efficiency of a plurality of cavity cells and to provide stable bonding by replacing wafer fusion bonding.

One technical problem to be solved by the present invention is to solve the low process yield due to the wafer fusion bonding process of the cMUT and to provide a cMUT device with a new structure that increases the area efficiency of a plurality of cavity cells.

One technical problem to be solved by the present invention is to solve the low process yield due to the wafer fusion bonding process of the cMUT and increase the area efficiency of a plurality of cavity cells Provide a method of manufacturing a cMUT device with a new structure is to do

A method of manufacturing a capacitive ultrasonic transducer element according to an embodiment of the present invention includes a silicon element substrate; a single crystal silicon membrane disposed on the silicon element substrate; an upper electrode disposed on the single crystal silicon membrane; and a first electrode pad and a second electrode pad disposed on a lower surface of the silicon element substrate. The silicon device substrate may include a plurality of active regions arranged in a matrix form on the silicon device substrate and operating as electrodes; a trench glass layer buried in the silicon device substrate to separate the active regions from each other; a through trench glass layer disposed to surround the trench glass layer and disposed to pass through the silicon device substrate; and a peripheral area disposed to surround the through trench glass layer. The single crystal silicon membrane includes a plurality of vacuum cavities disposed on an upper surface of the silicon device substrate to cover the through trench glass layer and aligned with the active regions. The plurality of vacuum cavities are formed by recessing a lower surface of the single crystal silicon membrane. The upper electrode extends into the peripheral area and is electrically connected to the first electrode pad through the peripheral area. The active regions are electrically connected to the second electrode pad.

In one embodiment of the present invention, the single crystal silicon membrane may be anodic bonded to the through trench glass layer and the trench glass layer.

In one embodiment of the present invention, the thickness of the trench glass layer is 1 μm to 10 μm, the height of the vacuum cavity is 0.1 μm to 0.8 μm, and the thickness of the single crystal silicon membrane is 0.5 μm to 2 μm, The silicon device substrate may have a thickness of 200 μm to 500 μm, the vacuum cavity may be circular, have a diameter of 10 μm to 50 μm, and a minimum distance between adjacent active regions may be 0.5 μm to 5 μm.

In one embodiment of the present invention, each of the vacuum cavities may further include a short circuit prevention insulating layer on a lower surface of the single crystal silicon membrane. The thickness of the short-circuit-preventing insulating layer may be 100 nm to 200 nm.

In one embodiment of the present invention, each of the active regions may further include a short circuit prevention insulating layer on its upper surface. The thickness of the short-circuit-preventing insulating layer may be 100 nm to 200 nm.

In one embodiment of the present invention, the through trench glass layer may have a width of 20 μm to 50 μm, and a minimum distance between adjacent active regions may be 0.5 μm to 5 μm.

In one embodiment of the present invention, the trench glass layer and the through trench glass layer may further include the silicon element substrate and a diffusion barrier for diffusion prevention.

In a method of manufacturing a capacitive ultrasonic transducer element according to an embodiment of the present invention, a silicon element substrate is patterned to form a first trench to form a plurality of active regions and a peripheral region, and the first trench is formed in the first trench. forming a second trench deeper than the first trench; disposing a glass substrate on the silicon device substrate and performing reflow to fill the first trench and the second trench with a glass layer to form a trench glass layer and a through-trench glass layer, respectively; planarizing an upper surface of the silicon device substrate to expose the active regions and polishing a lower surface of the silicon device substrate to expose the through trench glass layer; Forming vacuum cavities corresponding to the active regions and auxiliary cavities corresponding to the peripheral region by patterning a single crystal silicon layer of a silicon on insulator (SOI) substrate including a silicon substrate/insulation layer/single crystal silicon layer. ; anodic bonding the single crystal silicon layer of the silicon-on-insulator (SOI) substrate to the trench glass layer and the through-trench glass layer of the silicon device substrate; removing a silicon substrate and an insulating layer of the silicon-on-insulator (SOI) substrate; cutting the single crystal silicon layer to form the single crystal silicon membrane; and forming an upper electrode covering an upper surface of the single crystal silicon membrane and covering the peripheral region, a first electrode pad at a position corresponding to the peripheral region and a position corresponding to the active regions on the lower surface of the silicon device substrate. and forming a second electrode pad on

In one embodiment of the present invention, a silicon device substrate is patterned to form a first trench to form a plurality of active regions and a peripheral region, and a second trench deeper than the first trench is formed in the first trench. The step of doing may include forming a first trench etched through a patterning process, active regions that are not etched, and peripheral regions on the silicon device substrate; and forming a second trench etched through a patterning process in the first trench.

In one embodiment of the present invention, the thickness of the trench glass layer is 1 μm to 10 μm, the height of the vacuum cavity is 0.1 μm to 0.8 μm, and the thickness of the single crystal silicon membrane is 0.5 μm to 2 μm, The silicon device substrate may have a thickness of 200 μm to 500 μm, the vacuum cavity may be circular, have a diameter of 10 μm to 50 μm, and a minimum distance between adjacent active regions may be 0.5 μm to 5 μm.

A capacitive ultrasonic transducer element according to an embodiment of the present invention includes a silicon element substrate; a single crystal silicon membrane disposed on the silicon element substrate; an upper electrode disposed on the single crystal silicon membrane; and a first electrode pad and a second electrode pad disposed on a lower surface of the silicon element substrate. The silicon device substrate may include a plurality of active regions arranged in a matrix form on the silicon device substrate and operating as electrodes; a trench glass layer buried in the silicon device substrate to separate the active regions from each other; a through trench glass layer disposed to surround the trench glass layer and disposed to pass through the silicon device substrate; and a peripheral area disposed to surround the through trench glass layer. Top surfaces of the active regions are formed to be lower than top surfaces of the trench glass layer. A plurality of vacuum cavities are formed between the monocrystalline silicon membrane and the active regions. The single crystal silicon membrane is disposed on an upper surface of the silicon device substrate to cover the through trench glass layer. The upper electrode extends into the peripheral area and is electrically connected to the first electrode pad through the peripheral area. The active regions are electrically connected to the second electrode pad.

In one embodiment of the present invention, the single crystal silicon membrane may be anodic bonded to the through trench glass layer and the trench glass layer.

In one embodiment of the present invention, the depth of the trench glass layer is 1 μm to 10 μm, the height of the vacuum cavity is 0.1 μm to 0.8 μm, and the thickness of the single crystal silicon membrane is 0.5 μm to 2 μm, The silicon device substrate may have a thickness of 200 μm to 500 μm, the vacuum cavity may be circular, have a diameter of 10 μm to 50 μm, and a minimum distance between adjacent active regions may be 0.5 μm to 5 μm.

In one embodiment of the present invention, each of the vacuum cavities may further include a short circuit prevention insulating layer on a lower surface of the single crystal silicon membrane. The short-circuit-preventing insulating layer may have a thickness of 2 nm to 200 nm.

In one embodiment of the present invention, each of the active regions further includes an insulating layer on an upper surface thereof, and the insulating layer may have a thickness of 100 nm to 200 nm.

In one embodiment of the present invention, the through trench glass layer may have a width of 20 μm to 50 μm, and a minimum distance between adjacent active regions may be 0.5 μm to 5 μm.

In one embodiment of the present invention, the trench glass layer and the through trench glass layer may further include the silicon element substrate and a diffusion barrier for diffusion prevention.

In a method of manufacturing a capacitive ultrasonic transducer element according to an embodiment of the present invention, a silicon element substrate is patterned to form a first trench to form a plurality of active regions and a peripheral region, and the first trench is formed in the first trench. forming a second trench deeper than the first trench; disposing a glass substrate on the silicon device substrate and performing reflow to fill the first trench and the second trench with a glass layer to form a trench glass layer and a through-trench glass layer, respectively; planarizing an upper surface of the silicon device substrate to expose the active regions and the peripheral region and polishing a lower surface of the silicon device substrate to expose the through trench glass layer; forming a vacuum cavity and an auxiliary vacuum cavity by recessing the active regions and the peripheral region; anodic bonding the single-crystal silicon layer of the silicon-on-insulator (SOI) substrate including the silicon substrate/insulation layer/single-crystal silicon layer and the trench glass layer and through-trench glass layer of the silicon device substrate; removing a silicon substrate and an insulating layer of the silicon-on-insulator (SOI) substrate; cutting the single crystal silicon layer to form the single crystal silicon membrane; and forming an upper electrode covering an upper surface of the single crystal silicon membrane and locally covering the peripheral region, and corresponding to the first electrode pad and the active regions on the lower surface of the silicon element substrate at a position corresponding to the peripheral region. and forming a second electrode pad at a position where

In one embodiment of the present invention, a silicon device substrate is patterned to form a first trench to form a plurality of active regions and a peripheral region, and a second trench deeper than the first trench is formed in the first trench. The step of doing may include forming a first trench etched through a patterning process, active regions that are not etched, and peripheral regions on the silicon device substrate; and forming a second trench etched through a patterning process in the first trench.

In one embodiment of the present invention, the thickness of the trench glass layer is 1 μm to 10 μm, the height of the vacuum cavity is 0.1 μm to 0.8 μm, and the thickness of the single crystal silicon membrane is 0.5 μm to 2 μm, The silicon device substrate may have a thickness of 200 μm to 500 μm, the vacuum cavity may be circular, have a diameter of 10 μm to 50 μm, and a minimum distance between adjacent active regions may be 0.5 μm to 5 μm.

The cMUT device according to an embodiment of the present invention increases the bonding strength and yield of a highly integrated membrane and a silicon device substrate and can operate at a high frequency of 8 MHz or more.

1 is a plan view of a capacitive ultrasonic transducer element according to an embodiment of the present invention.
FIG. 2A is a plan view of a silicon element substrate showing one channel of the capacitive ultrasonic transducer element of FIG. 1 .
FIG. 2B is a plan view of a silicon element substrate and an SOI substrate showing one channel of the capacitive ultrasonic transducer element of FIG. 1 .
3 is a cross-sectional view taken along line AA' of FIG. 2B.
4 is a cross-sectional view taken along line BB' of FIG. 2B.
5A to 5M are cross-sectional views illustrating a manufacturing method of a capacitive ultrasonic transducer element according to an embodiment of the present invention.
6 is a cross-sectional view of a capacitive ultrasonic transducer element according to another embodiment of the present invention.
7 is a cross-sectional view of a capacitive ultrasonic transducer element according to another embodiment of the present invention.
8A to 8H are cross-sectional views illustrating a method of manufacturing a capacitive ultrasonic transducer element according to an embodiment of the present invention.

Wafer fusion bonding may cause defects due to differences in cleaning degree according to positions. When using a through-silicon through-electrode (TSV) penetrating a silicon substrate or a through-silicon insulating layer through a silicon substrate in a cMUT, a trench (or hole) for a through-silicon through-electrode is usually provided with a high etch aspect ratio of 10 or more and the high aspect ratio It is difficult to achieve a fine pitch due to the tapering of the trench.

Each channel of the cMUT includes a plurality of cavity cells, and as the number of vacuum cavity cells increases, the gap between the vacuum cavity cells is wasted for the TSV. Therefore, it is required to increase the degree of integration by reducing the spacing between the vacuum cavity cells.

The present invention can reduce the gap between vacuum cavity cells (or vacuum cavities) to increase the degree of integration and reduce the defect rate by using anodic bonding that is not sensitive to cleanliness. The gap between the vacuum cavity cells can be reduced using a dual trench process similar to the dual damascene process and a thermal reflow process of the glass plate.

According to the present invention, a first trench is formed on a silicon device substrate, and a second trench partially overlaps the first trench and is further recessed in the first trench. Subsequently, the silicon element substrate and the glass substrate are bonded using anodic bonding. The glass substrate is reflowed to form a glass layer by filling the first trench and the second trench. An upper surface of the silicon device substrate on which the glass layer is formed is planarized to expose the silicon device substrate. Also, a lower surface of the silicon device substrate is polished to expose the glass layer filling the second trench. next. Bonding yield can be improved by bonding the SOI substrate including vacuum cavities and the glass layer through anodic bonding. Subsequently, the silicon substrate and oxide layer of the SOI substrate are removed. In addition, by using the first trench, a low aspect ratio of the cavity cell can be realized, and thus an ultrasonic transducer with a small diameter can be manufactured. The degree of integration can be improved through an ultrasonic transducer with a small diameter, and ultrasonic waves of a high frequency band (more than 8 MHz) can be generated.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosed content will be thorough and complete, and the spirit of the present invention will be sufficiently conveyed to those skilled in the art. In the drawings, elements are exaggerated for clarity. Parts designated with like reference numerals throughout the specification indicate like elements.

1 is a plan view of a capacitive ultrasonic transducer element according to an embodiment of the present invention.

FIG. 2A is a plan view of a silicon element substrate showing one channel of the capacitive ultrasonic transducer element of FIG. 1 .

FIG. 2B is a plan view of a silicon element substrate and an SOI substrate showing one channel of the capacitive ultrasonic transducer element of FIG. 1 .

3 is a cross-sectional view taken along the line A-A' of FIG. 2B.

4 is a cross-sectional view taken along line BB' of FIG. 2B.

1 to 4, the capacitive ultrasonic transducer element 100 includes a silicon element substrate 110; a single crystal silicon membrane 132a disposed on the silicon element substrate 110; an upper electrode 136 disposed on the single crystal silicon membrane 132a; and a first electrode pad 14 and a second electrode pad 12 disposed on a lower surface of the silicon element substrate 110 . The capacitive ultrasonic transducer element 100 generates ultrasonic waves by vibration of the single crystal silicon membrane 132a.

The silicon device substrate 110 includes a plurality of active regions 116 arranged in a matrix form on the silicon device substrate 110 and operating as lower electrodes; a trench glass layer 114 buried in the silicon device substrate 110 to separate the active regions 116 from each other; a through-trench glass layer 112 disposed to surround the trench glass layer 114 and penetrating the silicon device substrate 110; and a peripheral region 118 disposed to surround the through trench glass layer 112 . Active regions 116 of the capacitive ultrasonic transducer element 100 operate as lower electrodes.

The single crystal silicon membrane 132a is disposed on the top surface of the silicon device substrate 110 to cover the through trench glass layer 112 and includes a plurality of vacuum cavities aligned with the active regions 116 ( 122). The plurality of vacuum cavities 122 are formed by recessing the lower surface of the single crystal silicon membrane 132a. The upper electrode 136 extends to the peripheral region 132 on the single crystal silicon membrane 132a and is electrically connected to the first electrode pad 14 through the peripheral region 132 . The active regions 116 are electrically connected to the second electrode pad 12 . The single-crystal silicon membrane 132a may be single-crystal silicon doped with an impurity or may not be doped.

The capacitive ultrasonic transducer element 100 may include a plurality of channels 10 . Each of the channels 10 may receive electrical signals of different phases through the second electrode pad 12 to perform beam-forming. Each channel 10 may include at least one vacuum cavity 122 . Preferably, each channel 10 may include a plurality of vacuum cavities 122 arranged in a matrix form. Illustratively, the vacuum cavities 122 may be in a 3x3 array to a 10x10 array. Each of the vacuum cavity cells formed by the vacuum cavities 122 operates at a natural frequency, but may not provide sufficient power. Accordingly, each channel 10 arranged in a matrix form can receive the same electrical signal and provide sufficient output power using a plurality of vacuum cavity cells. Each of the vacuum cavity cells requires a sufficiently thin membrane of 1 μm or less to lower the driving bias voltage. Also, the diameter of the vacuum cavity 122 can be designed according to the required frequency.

In order to increase the degree of directness of the vacuum cavity cells or vacuum cavities constituting each channel 10, they need to be arranged closely to each other. For such close arrangement, the single crystal silicon membrane 132a and the silicon element substrate 110 require sufficient adhesive strength. In addition, the spacing between the vacuum cavities 122 or the spacing w between the active regions depends on an etching aspect ratio for forming the trench glass layer 114 . Therefore, it is necessary to reduce the minimum distance w between the active regions 116 or the distance between the vacuum cavities 122 by lowering the etching aspect ratio.

The present invention reduces the minimum distance w between the active regions 116 by using the first trench 143 having a low etch aspect ratio, and the single crystal silicon membrane 132 and the glass layer of the silicon device substrate 110 The bonding strength can be increased by using (112,114) and anodic bonding. The width g of the second trench 145 having a high etch aspect ratio may be optimized to be 20 μm to 50 μm.

The silicon device substrate 110 may be a low-resistance silicon device substrate doped with high-concentration impurities. The impurity may be a p-type impurity or an n-type impurity. The silicon device substrate 110 may have a thickness of 200 μm to 500 μm.

An upper surface of the silicon device substrate 110 includes a plurality of island-shaped active regions 116 exposing the silicon device substrate 110, and a trench glass layer 114 disposed to surround the active regions 116. ), a through trench glass layer 112 disposed to surround the trench glass layer 114, and a peripheral region 118 disposed to surround the through trench glass layer 112. The plurality of active regions 116 operate as lower electrodes constituting a vacuum cavity cell or a unit storage battery.

Each of the active regions 116 may be circular, square, or hexagonal in plan view. Preferably, the active regions 116 may be circular. The active regions 116 may be arranged periodically. For example, the active regions 116 may be arranged in a matrix form. The active regions 116 protrude from the silicon device substrate 110 and operate as lower electrodes. The active regions 116 are portions of a protruding low-resistance silicon device substrate.

Trench glass layer 114 is an insulating layer separating the active regions 116 from each other. The trench glass layer 114 is glass, and may be, for example, borosilicate glass. The trench glass layer 114 may have a square or hexagonal shape in plan view. A plurality of active regions 116 in the trench glass layer 114 may be spaced apart from each other and arranged in an island shape. The trench glass layer 114 may be glass containing sodium (Na). The trench glass layer 114 may have a thickness of 1 μm to 10 μm. A thickness of the trench glass layer 114 may be 10 times or more than a height of the vacuum cavity 122 . Accordingly, the trench glass layer 114 may reduce parasitic capacitance between the silicon device substrate 110 and the upper electrode 136 . If the trench glass layer 114 is too deep, it is difficult to reduce the minimum distance w between the active regions 116 .

A width of the trench glass layer 114 or a minimum distance w between the active regions 116 may range from 0.5 μm to 5 μm. Preferably, the minimum distance (w) may be 0.5 μm to 2 μm. If the minimum distance (w) is less than 0.5 μm, bonding strength of anodic bonding may decrease. If the minimum distance w is greater than 2 μm, the degree of integration may decrease.

A through trench glass layer 112 is disposed through the silicon device substrate 110 . The through trench glass layer 112 may electrically insulate adjacent channels 10 from each other. The through trench glass layer 112 may be borosilicate glass. The through trench glass layer may be glass containing sodium (Na).

The through trench glass layer 112 may be formed by being etched by a deep trench reactive ion etching (RIE) process and then buried by a glass layer by a reflow process. In the deep trench process, an etch depth or a slope θ of the second trench may be determined according to an etch aspect ratio. The silicon device substrate 110 may have a thickness of 200 μm to 500 μm. Therefore, in order to stably pass through the silicon device substrate 110, the through-trench glass layer 112 may have a width (g) of 20 μm to 50 μm.

According to a modified embodiment of the present invention, the trench glass layer and the through trench glass layer may further include a diffusion barrier layer (not shown) between the silicon device substrates to prevent diffusion. The diffusion barrier layer may be a silicon oxide layer or an aluminum oxide layer.

The peripheral region 118 is disposed outside the through trench glass layer 112 , and preferably may be disposed to surround the through trench glass layer 112 . The peripheral region 118 may be an exposed portion of the upper surface of the silicon device substrate 110 . The upper surface of the peripheral region 118 is coplanar with the upper surface of the active region 116 . The peripheral area 118 may be used as an electrical connection path connecting the upper electrode 136 and the first electrode pad 14 . The first electrode pad 14 may be connected to ground.

The single-crystal silicon membrane 132a may be single-crystal silicon not doped with impurities or doped single-crystal silicon. The single crystal silicon membrane 132a may operate as a diaphragm. The single crystal silicon membrane 132a may have a thickness of 0.5 μm to 2 μm. The vacuum cavities 122 may be formed on a lower surface of the single crystal silicon membrane 132a. The shape of the vacuum cavity 122 may be circular, square, or hexagonal. The shape of the vacuum cavity 122 is the same as that of the active region 116 and may be slightly larger than the active region. The diameter of the circular vacuum cavity 122 may be 10 μm to 50 μm.

For example, when the thickness of the single crystal silicon membrane 132a is 1 μm, the diameter of the circular vacuum cavity 122 is 20 μm, and the height of the vacuum cavity 122 is 0.5 μm, the vibration natural frequency is about It may be 8 MHz.

The vibration natural frequency of the cMUT of the present invention may be 8 MHz or more. To optimize the performance of the ultrasonic transducer, the thickness t of the single crystal silicon membrane 132a may be 2 μm or less. Specifically, the thickness t of the single crystal silicon membrane 132a may be 2 to 10 times the height of the vacuum cavity 122 . The single-crystal silicon membrane 132a may provide stable vibration characteristics compared to a structure in which a support portion is provided using a separate material by using single-crystal silicon having a recessed structure. In addition, when the vibration frequency is changed, the thickness t of the single crystal silicon membrane 132a can be easily designed and changed.

The single crystal silicon membrane 132a includes vacuum cavities 122 of the same shape on its lower surface. Each of the vacuum cavities 122 is disposed to face the active regions 116 . The height of the vacuum cavity 122 may be 0.1 μm to 1 μm. Preferably, the height of the vacuum cavity 122 may be 0.1 μm to 0.8 μm.

The vacuum cavity 122 may be circular, square, or hexagonal. A shape of the vacuum cavity may be the same as that of the active region. A portion protruding from the lower surface of the single crystal silicon membrane 132a may perform anodic bonding with the glass layer and support the vacuum cavity. Also, the diameter of the vacuum cavity 122 may be substantially equal to or slightly larger than the diameter of the active region 116 . Accordingly, a portion protruding from the lower surface of the single crystal silicon membrane 132a may be anodic bonded to the trench glass layer 112 to be used as a support member.

The upper electrode 136 may have a stacked structure of Ti/Au (10 nm/100 nm) or Ti/Al (10 nm/100 nm). The Ti may act as an adhesive layer and an anti-diffusion layer. The upper electrodes 136 may be disposed in the same size as the vacuum cavity 122 or in a small circular shape at positions corresponding to the vacuum cavity 122, and may be connected to each other through wires 136a. The wiring 136a may extend in a first arrangement direction of the vacuum cavities 122 arranged in a matrix form, a second arrangement direction perpendicular to the first arrangement direction, and a diagonal direction thereof. The upper electrode 136 may extend in a diagonal direction from the single crystal silicon membrane 132a and be connected to an auxiliary upper electrode 136b disposed in the peripheral region 118 . The shape of the upper electrode can reduce parasitic capacitance.

According to a modified embodiment of the present invention, the upper electrode 136 may be changed into various shapes as long as it covers the vacuum cavities 122 of the single crystal silicon membrane 132a.

The first electrode pad 14 may be disposed on a lower surface of the peripheral region 118 of the silicon device substrate 110 . In addition, the second electrode pad 12 may be disposed on a lower surface of the active region 116 of the silicon device substrate 110 . The first electrode pad 14 may be electrically connected to the upper electrode 136 through the peripheral region 118 . The second electrode pad 12 may be electrically connected to the active region 116 . The first electrode pad 14 and the second electrode pad 12 may have a Ti/Au stack structure.

When a high-voltage pulse signal is applied to the single-crystal silicon membrane 132a in the capacitive transducer 100 such as cMUT, mechanical vibration of the single-crystal silicon membrane 132a is caused by the action of electrostatic force. That is, the electrical signal is converted into a sound pressure signal. As the sound pressure signal passes through the human body, a part of the signal is reflected with a time difference as an echo signal of various intensities due to a difference in acoustic impedance between various tissue layers of the human body. The capacitive transducer 100 may receive a reflected signal.

When the negative pressure signal reflected and returned is applied to the capacitive transducer 100, the capacitance of the capacitive transducer 100 is changed. The change in capacitance is converted back into an electrical signal and transmitted to the receiving end of the circuit. Analog front end (AFE) integrated circuit (IC) amplifies weak electrical signals through a low-noise amplifier at the analog receiver and a time-to-gain compensation amplifier (TGC) capable of converting the gain according to the time difference of the echo signal. do. The amplified signal is transmitted to the digital signal processing unit through an analog-to-digital converter (ADC).

The analog circuit board 20 includes an analog front end (AFE) integrated circuit (IC) and may be connected to the AFE-IC through the first electrode pad 14 and the second electrode pad 12 .

The analog circuit board 20 may be disposed under the silicon device substrate 120 and packaged as a single chip.

5A to 5M are cross-sectional views illustrating a manufacturing method of a capacitive ultrasonic transducer element according to an embodiment of the present invention.

Referring to FIGS. 5A to 5M , a method of manufacturing the capacitive ultrasonic transducer element 100 includes a plurality of active regions 116 by forming a first trench 143 by patterning a silicon element substrate 110 . and forming a peripheral region 118 and forming a second trench 145 deeper than the first trench 143 within the first trench 143 ; A glass substrate 146 is disposed on the silicon device substrate 110 and reflowed to fill the first trench 143 and the second trench 145 with a glass layer 146a to form a trench glass layer 114 and forming through-trench glass layers 112, respectively; planarizing an upper surface of the silicon device substrate 110 to expose the active regions 116 and polishing a lower surface of the silicon device substrate 110 to expose the through trench glass layer 112; Vacuum cavities 122 corresponding to the active regions 116 and forming an auxiliary cavity 122a corresponding to the peripheral area 118; anodic bonding the single crystal silicon layer 132 of the silicon-on-insulator (SOI) substrate 130 to the trench glass layer 114 and through-trench glass layer 112 of the silicon element substrate; removing the silicon substrate 131a and the insulating layer 131b of the silicon-on-insulator (SOI) substrate; cutting the single crystal silicon layer 132 to form the single crystal silicon membrane 132a; and an upper electrode 136 covering an upper surface of the single crystal silicon membrane 132a and locally covering the peripheral region 118, wherein a first first electrode 136 is positioned on the lower surface of the silicon device substrate to correspond to the peripheral region. and forming second electrode pads 12 at locations corresponding to the electrode pads 14 and the active regions.

5A to 5C, the silicon device substrate 110 is patterned to form a first trench 143 to form a plurality of active regions 116 and a peripheral region 118, and the first trench 143 ) to form a second trench 145 deeper than the first trench.

Referring to FIG. 5A , an etched first trench 143 , unetched active regions 116 , and peripheral regions 118 may be formed on the silicon device substrate 110 through a patterning process. Specifically, a first etching mask 142 may be formed on the silicon device substrate 110 . The first etching mask 142 may be a photoresist pattern. A first trench 143 may be formed by anisotropic etching using the first etching mask 142 . The first trench 143 may define a plurality of active regions 116 and a peripheral region 118 . The plurality of active regions 116 may be spaced apart from each other in an island shape and disposed within the peripheral region 118 . The plurality of active regions 116 and the peripheral region 118 may be regions that are not etched by the first etch mask 142 . The first etching mask 142 may be a photoresist pattern. The plurality of active regions 116 are arranged in a matrix form, and a minimum distance w between adjacent active regions 116 may be 0.5 μm to 5 μm. The depth of the first trench 143 may be 1 μm to 10 μm. Accordingly, it has a low etch aspect ratio, and the etch shape can be performed without tapering.

Referring to FIGS. 5B and 5C , the first etching mask 142 may be removed, and a second trench 145 may be formed on the first trench to surround the active regions 116 . A second trench 145 etched through a patterning process may be formed in the first trench 143 . The second etch mask 144 forming the second trench 145 may be used to etch silicon of 200 μm to 500 μm. The second etching mask 144 may be a photoresist pattern or a hard mask pattern. Deep reactive ion etching may be performed using the second etching mask 144 . An etch aspect ratio of the second trench 145 may be 10 or more. A taper angle of the second trench 145 may be 85 degrees to 90 degrees.

By disposing the second trench 145 within the first trench 143 , the etching aspect ratio in the second trench 145 may be reduced. In addition, in the process of forming the second trenches 145, most of the first trenches 143 are covered with the second etch mask 144, thereby reducing the microloading effect in which etching characteristics depend on the pattern size. The second trench 145 may be formed by a Bosch process. Through the double trench process, a narrow gap between the active regions 116 may be secured, and separation between channels may be performed. Subsequently, the second etch mask 144 may be removed.

According to a modified embodiment of the present invention, a double trench process is performed in which a deep trench (200 μm to 500 μm) is first formed with a first mask and the deep trench and thin trench (1 μm to 10 μm) are simultaneously etched with a second mask. can

5D and 5E, a glass substrate 146 is disposed on the silicon device substrate 110 and reflowed to form the first trench 143 and the second trench 145 as a glass layer. 146a to form a trench glass layer 114 and a through trench glass layer 114, respectively. The glass substrate 146 may be borosilicated glass. The glass substrate 146 may be bonded to the silicon device substrate 110 in a high vacuum state. Subsequently, the bonded silicon-glass substrate may be subjected to a reflow process in a furnace at 500 degrees Celsius or higher. Accordingly, the glass substrate 146 may fill the first trench 143 and the second trench 145 . The first trench 143 may be filled with a glass layer to form the trench glass layer 114 , and the second trench 145 may be filled with a glass layer to form the through trench glass layer 112 . The trench glass layer 114 may have a square or hexagonal shape in plan view. A plurality of active regions 116 in the trench glass layer 114 may be arranged spaced apart from each other. The through trench glass layer 112 is disposed outside the trench glass layer 114 .

Referring to FIG. 5F, the upper surface of the silicon device substrate 110 is planarized to expose the active regions 116 and the peripheral region 118, and the lower surface of the silicon device substrate 110 is polished to reveal the through hole. The trench glass layer 112 is exposed. The planarization process and the polishing process may be performed by a chemical mechanical polishing (CMP) process. Accordingly, each channel is electrically isolated from each other. The CMP process may provide surface steps according to materials to the surface.

5G and 5H, vacuum cavities corresponding to the active regions 116 are formed by patterning a single crystal silicon layer 132 of a silicon on insulator (SOI) substrate including a silicon substrate/insulation layer/single crystal silicon layer. An auxiliary cavity 122a corresponding to the fields 122 and the peripheral area 118 is formed. The auxiliary cavity 122a can suppress bonding defects due to surface steps according to materials on the surface of the CMP process.

The single crystal silicon layer 132 may have a thickness t of 1 μm to 2.0 μm. A single crystal silicon layer may be doped or undoped. The insulating layer 131a may be a silicon oxide film. The patterning depth of the single crystal silicon layer 132 corresponds to the height of the vacuum cavity 122 and may be 0.3 μm to 0.8 μm. The vacuum cavity 122 may have a circular shape and have a diameter of 10 μm to 50 μm. The vacuum cavity 122 may be slightly larger than the active region 116 and may be vertically aligned with the active region 116 . An auxiliary cavity 122a is disposed on the peripheral area 118 . The auxiliary cavity 122a may suppress misalignment due to a surface step during anodic bonding.

Referring to FIG. 5I , a short circuit prevention insulating layer 123 is formed on the lower surface of the single crystal silicon membrane 132a in each of the vacuum cavities 122 . The thickness of the short circuit prevention insulating layer 123 may be 100 nm to 200 nm. The short-circuit preventing insulating layer 123 prevents a short circuit between the single-crystal silicon membrane 132a and the active region 116 when the single-crystal silicon layer 132 is doped with an impurity. The short circuit prevention insulating layer 123 may be a silicon oxide film. The short circuit prevention insulating layer 123 may be formed through a deposition and etching patterning process or a selective oxidation process using a mask.

Referring to FIG. 5J , the single crystal silicon layer 132 of the silicon-on-insulator (SOI) substrate 130 and the trench glass layer 114 and through-trench glass layer 112 of the silicon device substrate 110 are formed. Anodic bonding. Anodic bonding may be performed by applying an electric field and pressure at a high temperature of 200 degrees Celsius or more in a vacuum container. Accordingly, the single crystal silicon layer 132 is anodic bonded to the trench glass layer 114 and through trench glass layer 112 of the silicon device substrate 110 by movement of Na ions. can The anodic bonding can provide stable bonding regardless of surface cleanliness and flatness.

Referring to FIG. 5K , the silicon substrate 131a and the insulating layer 131b of the silicon-on-insulator (SOI) substrate 130 are removed. The silicon substrate 131a may be removed by silicon polishing and chemical etching. In addition, the insulating layer 131b may be removed by reactive ion etching.

Referring to FIG. 5L , the single crystal silicon layer 132 is cut to form the single crystal silicon membrane 132a. Cutting the single crystal silicon layer 132 may be performed to remove the auxiliary cavity 122a by reactive ion etching. The single crystal silicon layer 132 may be substantially aligned with the through trench glass layer 112 by cutting to remove the auxiliary cavity 122a.

Referring to FIG. 5M , an upper electrode 136 covering the upper surface of the single crystal silicon membrane 132a and locally covering the peripheral region 118 is formed, and the peripheral region 118 is formed on the lower surface of the silicon device substrate 110. A first electrode pad 14 is formed at a location corresponding to the region 118 and a second electrode pad 12 is formed at a location corresponding to the active regions 116 . The upper electrode 136 may have a stacked structure of Ti/Au (10 nm/100 nm) or Ti/Al (10 nm/100 nm). The upper electrode 136 may be formed by patterning after depositing a conductive layer. The first electrode pad 14 and the second electrode pad 12 may be formed by patterning after depositing the conductive layer. The first electrode pad 14 and the second electrode pad 12 may be made of Ti/Au.

6 is a cross-sectional view of a capacitive ultrasonic transducer element according to another embodiment of the present invention.

Referring to FIG. 6 , the capacitive ultrasonic transducer element 100a includes a silicon element substrate 110; a single crystal silicon membrane (132a) disposed on the silicon substrate (110); an upper electrode 136 disposed on the single crystal silicon membrane 132a; and a first electrode pad 14 and a second electrode pad 12 disposed on a lower surface of the silicon element substrate 110 . The capacitive ultrasonic transducer element 100 generates ultrasonic waves by vibrating a single crystal silicon membrane.

The silicon device substrate 110 includes a plurality of active regions 116 arranged in a matrix form on the silicon device substrate 110 and operating as electrodes; a trench glass layer 114 buried in the silicon device substrate 110 to separate the active regions 116 from each other; a through-trench glass layer 112 disposed to surround the trench glass layer 114 and penetrating the silicon device substrate 110; and a peripheral region 118 disposed to surround the through trench glass layer 112 . Active regions 116 of the capacitive ultrasonic transducer element 100 operate as lower electrodes.

The single crystal silicon membrane 132a is disposed on the top surface of the silicon device substrate 110 to cover the through trench glass layer 112 and includes a plurality of vacuum cavities aligned with the active regions 116 ( 122). The plurality of vacuum cavities 122 are formed by recessing the lower surface of the single crystal silicon membrane 132a. The upper electrode 136 extends to the peripheral region 132 on the single crystal silicon membrane 132a and is electrically connected to the first electrode pad 14 through the peripheral region 132 . The active regions 116 are electrically connected to the second electrode pad 12 . The single-crystal silicon membrane 132a may be single-crystal silicon doped with an impurity or may not be doped.

Each of the active regions 116 further includes an anti-short insulating layer 116a on its upper surface. The short circuit prevention insulating layer 116a may have a thickness of 100 nm to 200 nm and may be a silicon oxide film. The short circuit prevention insulating layer 116a may be a silicon oxide layer.

7 is a cross-sectional view of a capacitive ultrasonic transducer element according to another embodiment of the present invention.

Referring to FIG. 7 , the capacitive ultrasonic transducer element 200 includes a silicon element substrate 110; a single crystal silicon membrane 232a disposed on the silicon substrate 110; an upper electrode 136 disposed on the single crystal silicon membrane 232a; and a first electrode pad 14 and a second electrode pad 12 disposed on a lower surface of the silicon element substrate 110 . The capacitive ultrasonic transducer element 200 generates ultrasonic waves by vibration of the single crystal silicon membrane 232a.

The silicon device substrate 110 includes a plurality of active regions 116 arranged in a matrix form on the silicon device substrate 110 and operating as lower electrodes; a trench glass layer 114 buried in the silicon device substrate 110 to separate the active regions 116 from each other; a through-trench glass layer 112 disposed to surround the trench glass layer 114 and penetrating the silicon device substrate 110; and a peripheral region 118 disposed to surround the through trench glass layer 112 .

Top surfaces of the active regions 116 are formed to be lower than the top surface of the trench glass layer 114 , and a plurality of vacuum cavities 222 are formed between the single crystal silicon membrane 232a and the active regions 116 . ) is formed between The single crystal silicon membrane 232a is disposed on the upper surface of the silicon device substrate 110 to cover the through trench glass layer 112 . The upper electrode 136 extends to the peripheral region 118 and is electrically connected to the first electrode pad 14 through the peripheral region 118 . The active regions 116 are electrically connected to the second electrode pad 12 .

The trench glass layer 114 and the through trench glass layer 112 may further include a diffusion barrier layer 245 between the silicon device substrate 110 to prevent diffusion. The diffusion barrier layer 245 may be a silicon oxide layer or an aluminum oxide layer. The anti-diffusion layer 245 may be disposed on side surfaces and lower surfaces of the first trench 143 and the second trench 146 . The diffusion barrier layer 245 may be formed by an atomic layer deposition process. The anti-diffusion layer 245 may suppress diffusion of metal atoms of the glass layer into the silicon device substrate. Accordingly, the impurity concentration distribution of the active regions may be stably maintained.

A space between the active regions 116 and the single crystal silicon membrane 232a forms a vacuum cavity 222 . The height of the vacuum cavity may be 0.1 μm to 0.5 μm. The vacuum cavity 222 may have a circular shape and may have a diameter of 10 μm to 50 μm. The trench glass layer 114 may have a thickness of 1 μm to 10 μm. The single crystal silicon membrane 232a may have a thickness of 0.5 μm to 2 μm. The silicon device substrate 110 may have a thickness of 200 μm to 500 μm. The minimum distance w between adjacent active regions 116 may be 0.5 μm to 5 μm.

8A to 8H are cross-sectional views illustrating a method of manufacturing a capacitive ultrasonic transducer element according to an embodiment of the present invention.

Referring to FIGS. 5A to 5M and FIGS. 8A to 8H , a method of manufacturing a capacitive ultrasonic transducer element 200 includes forming a first trench 143 by patterning a silicon element substrate 110 to form a plurality of forming active regions 116 and peripheral regions 118 and forming a second trench 145 deeper than the first trench 143 in the first trench 143; A glass substrate is disposed on the silicon device substrate 110 and reflowed to fill the first trench 143 and the second trench 145 with a glass layer 146a to form a trench glass layer 114 and through-trench glass. forming layers 112, respectively; The upper surface of the silicon device substrate 110 is planarized to expose the active regions 116 and the peripheral region 118, and the lower surface of the silicon device substrate is polished to expose the through trench glass layer 112. step of doing; forming a vacuum cavity 222 and an auxiliary vacuum cavity 222a by recess etching the active regions 116 and the peripheral region 118; The single crystal silicon layer 232 of the silicon on insulator (SOI) substrate 230 including a silicon substrate/insulation layer/single crystal silicon layer, the trench glass layer 114 of the silicon device substrate 120, and through trench glass anodic bonding layer 112; removing the silicon substrate 231b and the insulating layer 231a of the silicon-on-insulator (SOI) substrate; cutting the single crystal silicon layer 232 to form the single crystal silicon membrane 232a; and an upper electrode 136 covering an upper surface of the single crystal silicon membrane 232a and locally covering the peripheral area, and a first electrode 136 positioned on the lower surface of the silicon element substrate 120 corresponding to the peripheral area. and forming second electrode pads 12 at positions corresponding to the electrode pads 14 and the active regions.

Again, referring to FIGS. 5A to 5C , the silicon device substrate 110 is patterned to form a first trench 143 to form a plurality of active regions 116 and a peripheral region 118, and the first trench 143 is formed. A second trench 145 deeper than the first trench is formed in the trench 143 .

Referring to FIG. 8A , a diffusion barrier layer 245 covering side surfaces and lower surfaces of the first trench 143 and the second trench 145 may be deposited. The diffusion barrier layer 245 may be a silicon oxide layer or an aluminum oxide layer. The anti-diffusion layer 245 may have a thickness of several nm to several hundreds of nm.

Referring to FIG. 8B , the silicon device substrate 110 is reflowed using a glass substrate to fill the first trench and the second trench with a glass layer 146a to form a trench glass layer 114 and through-trench glass. Layers 114 may be formed separately.

Referring to FIG. 8C , the upper surface of the silicon device substrate 120 is planarized to expose the active regions 116 and the peripheral region 118, and the lower surface of the silicon device substrate 110 is polished to The through trench glass layer 112 may be exposed.

Referring to FIG. 8D , a vacuum cavity 222 and an auxiliary vacuum cavity 222a may be formed by recess etching the active regions 116 and the peripheral region 118 . The recess etching may be wet etching or dry etching. A depth of the recess etching may be 0.1 μm to 0.5 μm. Accordingly, the height of the vacuum cavity 22 may be 0.1 μm to 0.5 μm.

Referring to FIGS. 8E and 8F , the single crystal silicon layer 232 of the silicon on insulator (SOI) 230 substrate including the silicon substrate 231b/insulation layer 231a/single crystal silicon layer 232 and the silicon The trench glass layer 114 and the through trench glass layer 112 of the device substrate 120 are anodic bonded.

An anti-short insulating layer 223 is formed on the single crystal silicon layer 232 at a position corresponding to each of the vacuum cavities 222 . The thickness of the short circuit prevention insulating layer 223 may be 100 nm to 200 nm. The short-circuit preventing insulating layer 223 prevents a short circuit between the single-crystal silicon membrane 232a and the active region 116 when the single-crystal silicon layer 232 is doped with an impurity. The short circuit prevention insulating layer 223 may be a silicon oxide film. The short circuit prevention insulating layer 223 may be formed through a deposition and etching patterning process or a selective oxidation process using a mask.

Referring to FIG. 8G , the silicon substrate and the insulating layer of the silicon-on-insulator (SOI) substrate are removed.

Referring to FIG. 8H , the single crystal silicon layer 232 is cut to form the single crystal silicon membrane 232a.

Next, an upper electrode 136 covering the upper surface of the single crystal silicon membrane 232a and locally covering the peripheral region is formed, and a first electrode pad is formed on the lower surface of the silicon device substrate at a position corresponding to the peripheral region. A second electrode pad 12 is formed at a position corresponding to (14) and the active regions.

According to a modified embodiment of the present invention, the short circuit prevention insulating layer 223 may be formed on the active region.

Although the present invention has been shown and described with respect to specific preferred embodiments, the present invention is not limited to these embodiments, and the technical idea of the present invention claimed in the claims by those skilled in the art to which the present invention belongs It includes all of the various forms of embodiments that can be practiced within the scope of not departing from.

110: silicon element substrate
112: through trench glass layer
114: trench glass layer
116 Active areas
118 Peripheral area
122: vacuum cavity
132a single crystal silicon membrane
136: upper electrode

Claims (20)

a silicon device substrate;
a single crystal silicon membrane disposed on the silicon element substrate;
an upper electrode disposed on the single crystal silicon membrane; and
A first electrode pad and a second electrode pad disposed on a lower surface of the silicon element substrate,
The silicon device substrate is:
a plurality of active regions arranged in a matrix form on the silicon element substrate and operating as electrodes;
a trench glass layer buried in the silicon device substrate to separate the active regions from each other;
a through trench glass layer disposed to surround the trench glass layer and disposed to pass through the silicon device substrate; and
A peripheral region disposed to surround the through trench glass layer; includes;
the single crystal silicon membrane includes a plurality of vacuum cavities disposed on an upper surface of the silicon device substrate to cover the through trench glass layer and aligned with the active regions;
The plurality of vacuum cavities are formed by recessing the lower surface of the single crystal silicon membrane,
The upper electrode extends into the peripheral region and is electrically connected to the first electrode pad through the peripheral region,
The active regions are capacitive ultrasonic transducer elements, characterized in that electrically connected to the second electrode pad. According to claim 1,
The capacitive ultrasonic transducer element, characterized in that the single crystal silicon membrane is anodic bonded to the through trench glass layer and the trench glass layer. According to claim 1,
The thickness of the trench glass layer is 1 μm to 10 μm ,
The height of the vacuum cavity is 0.1 μm to 0.8 μm ,
The thickness of the single crystal silicon membrane is 0.5 μm to 2 μm ,
The thickness of the silicon device substrate is 200 μm to 500 μm ,
The vacuum cavity is circular and has a diameter of 10 μm to 50 μm ,
A capacitive ultrasonic transducer element, characterized in that the minimum distance between adjacent active regions is 0.5 μm to 5 μm . According to claim 1,
Each of the vacuum cavities further includes an anti-short insulating layer on a lower surface of the single crystal silicon membrane;
The capacitive ultrasonic transducer element, characterized in that the thickness of the short-circuit preventing insulating layer is 100nm to 200nm. According to claim 1,
Each of the active regions further includes an anti-short insulating layer on an upper surface thereof;
The capacitive ultrasonic transducer element, characterized in that the thickness of the short-circuit preventing insulating layer is 100nm to 200nm. According to claim 1,
The width of the through trench glass layer is 20 μm to 50 μm ,
A capacitive ultrasonic transducer element, characterized in that the minimum distance between adjacent active regions is 0.5 μm to 5 μm . According to claim 1,
The capacitive type ultrasonic transducer element, characterized in that the trench glass layer and the through-trench glass layer further include the silicon element substrate and a diffusion prevention layer for diffusion prevention. patterning the silicon device substrate to form a first trench to form a plurality of active regions and a peripheral region, and forming a second trench deeper than the first trench within the first trench;
disposing a glass substrate on the silicon device substrate and performing reflow to fill the first trench and the second trench with a glass layer to form a trench glass layer and a through-trench glass layer, respectively;
planarizing an upper surface of the silicon device substrate to expose the active regions and polishing a lower surface of the silicon device substrate to expose the through trench glass layer;
Forming vacuum cavities corresponding to the active regions and auxiliary cavities corresponding to the peripheral region by patterning a single crystal silicon layer of a silicon on insulator (SOI) substrate including a silicon substrate/insulation layer/single crystal silicon layer. ;
anodic bonding the single crystal silicon layer of the silicon-on-insulator (SOI) substrate to the trench glass layer and the through-trench glass layer of the silicon device substrate;
removing a silicon substrate and an insulating layer of the silicon-on-insulator (SOI) substrate;
cutting the single crystal silicon layer to form a single crystal silicon membrane; and
An upper electrode covering an upper surface of the single crystal silicon membrane and covering the peripheral region is formed, and a first electrode pad is formed on a lower surface of the silicon element substrate at a position corresponding to the peripheral region and at a position corresponding to the active regions. A method of manufacturing a capacitive ultrasonic transducer element, comprising the step of forming a second electrode pad. According to claim 8,
Patterning the silicon device substrate to form a first trench to form a plurality of active regions and a peripheral region, and forming a second trench deeper than the first trench in the first trench includes:
forming an etched first trench and unetched active regions and peripheral regions on the silicon device substrate through a patterning process; and
Forming a second trench etched through a patterning process in the first trench; manufacturing method of a capacitive ultrasonic transducer element, characterized in that it comprises a. According to claim 8,
The thickness of the trench glass layer is 1 μm to 10 μm ,
The height of the vacuum cavity is 0.1 μm to 0.8 μm ,
The thickness of the single crystal silicon membrane is 0.5 μm to 2 μm ,
The thickness of the silicon device substrate is 200 μm to 500 μm ,
The vacuum cavity is circular and has a diameter of 10 μm to 50 μm ,
A method for manufacturing a capacitive ultrasonic transducer element, characterized in that the minimum distance between adjacent active regions is 0.5 μm to 5 μm . a silicon device substrate;
a single crystal silicon membrane disposed on the silicon element substrate;
an upper electrode disposed on the single crystal silicon membrane; and
A first electrode pad and a second electrode pad disposed on a lower surface of the silicon element substrate,
The silicon device substrate is:
a plurality of active regions arranged in a matrix form on the silicon element substrate and operating as electrodes;
a trench glass layer buried in the silicon device substrate to separate the active regions from each other;
a through trench glass layer disposed to surround the trench glass layer and disposed to pass through the silicon device substrate; and
A peripheral region disposed to surround the through trench glass layer; includes;
Top surfaces of the active regions are formed to be lower than top surfaces of the trench glass layer;
A plurality of vacuum cavities are formed between the single crystal silicon membrane and the active regions;
the single crystal silicon membrane is disposed on an upper surface of the silicon element substrate to cover the through trench glass layer;
The upper electrode extends into the peripheral region and is electrically connected to the first electrode pad through the peripheral region,
The active regions are capacitive ultrasonic transducer elements, characterized in that electrically connected to the second electrode pad. According to claim 11,
The capacitive ultrasonic transducer element, characterized in that the single crystal silicon membrane is anodic bonded to the through trench glass layer and the trench glass layer. According to claim 11,
The depth of the trench glass layer is 1 μm to 10 μm ,
The height of the vacuum cavity is 0.1 μm to 0.8 μm ,
The thickness of the monocrystalline silicon membrane is 0.5 μm to 2 μm ,
The thickness of the silicon device substrate is 200 μm to 500 μm ,
The vacuum cavity is circular and has a diameter of 10 μm to 50 μm ,
A capacitive ultrasonic transducer element, characterized in that the minimum distance between adjacent active regions is 0.5 μm to 5 μm . According to claim 11,
Each of the vacuum cavities further includes an anti-short insulating layer on a lower surface of the single crystal silicon membrane;
The capacitive ultrasonic transducer element, characterized in that the short-circuit preventing insulating layer is 2nm to 200nm. According to claim 11,
Each of the active regions further includes an insulating layer on an upper surface thereof;
The insulating layer is a capacitive ultrasonic transducer element, characterized in that 100nm to 200nm. According to claim 11,
The width of the through trench glass layer is 20 μm to 50 μm ,
A capacitive ultrasonic transducer element, characterized in that the minimum distance between adjacent active regions is 0.5 μm to 5 μm . According to claim 11,
The capacitive type ultrasonic transducer element, characterized in that the trench glass layer and the through-trench glass layer further include the silicon element substrate and a diffusion prevention layer for diffusion prevention. patterning the silicon device substrate to form a first trench to form a plurality of active regions and a peripheral region, and forming a second trench deeper than the first trench within the first trench;
disposing a glass substrate on the silicon device substrate and performing reflow to fill the first trench and the second trench with a glass layer to form a trench glass layer and a through-trench glass layer, respectively;
planarizing an upper surface of the silicon device substrate to expose the active regions and the peripheral region and polishing a lower surface of the silicon device substrate to expose the through trench glass layer;
forming a vacuum cavity and an auxiliary vacuum cavity by recessing the active regions and the peripheral region;
anodic bonding the single crystal silicon layer of a silicon on insulator (SOI) substrate including a silicon substrate/insulation layer/single crystal silicon layer and the trench glass layer and through trench glass layer of the silicon device substrate;
removing a silicon substrate and an insulating layer of the silicon-on-insulator (SOI) substrate;
cutting the single crystal silicon layer to form a single crystal silicon membrane; and
An upper electrode covering an upper surface of the single crystal silicon membrane and locally covering the peripheral region is formed, and a first electrode pad is formed on a lower surface of the silicon element substrate at a position corresponding to the peripheral region and a first electrode pad corresponding to the active regions is formed. A method for manufacturing a capacitive ultrasonic transducer element comprising the step of forming a second electrode pad at a position. According to claim 18,
Patterning the silicon device substrate to form a first trench to form a plurality of active regions and a peripheral region, and forming a second trench deeper than the first trench in the first trench includes:
forming an etched first trench and unetched active regions and peripheral regions on the silicon device substrate through a patterning process; and
Forming a second trench etched through a patterning process in the first trench; manufacturing method of a capacitive ultrasonic transducer element, characterized in that it comprises a. According to claim 18,
The thickness of the trench glass layer is 1 μm to 10 μm ,
The height of the vacuum cavity is 0.1 μm to 0.8 μm ,
The thickness of the single crystal silicon membrane is 0.5 μm to 2 μm ,
The thickness of the silicon device substrate is 200 μm to 500 μm ,
The vacuum cavity is circular and has a diameter of 10 μm to 50 μm ,
A method for manufacturing a capacitive ultrasonic transducer element, characterized in that the minimum distance between adjacent active regions is 0.5 μm to 5 μm .

Images