WO2018169298A1

WO2018169298A1 - Ultrasonic fingerprint sensor and manufacturing method therefor

Info

Publication number: WO2018169298A1
Application number: PCT/KR2018/002970
Authority: WO
Inventors: 박상영; 박영태
Original assignee: 주식회사 베프스
Priority date: 2017-03-16
Filing date: 2018-03-14
Publication date: 2018-09-20

Abstract

An ultrasonic fingerprint sensor and a manufacturing method therefor are provided. The ultrasonic fingerprint sensor comprises: a piezoelectric layer including a sensor region having a plurality of piezoelectric rods arranged so as to form a sensor array and having an insulating material formed to fill the periphery of each piezoelectric rod, and a silicon substrate coming in contact with at least one of the side surfaces of the sensor region so as to form an edge region; a plurality of first electrode bars arranged in a first direction along the upper surface of the piezoelectric layer; a plurality of second electrode bars arranged in a direction orthogonal to the first direction, along the lower surface of the piezoelectric layer; and a rigid panel attached to the upper surface of the piezoelectric layer and an upper part of the first electrode bar.

Description

Ultrasonic Fingerprint Sensor and Manufacturing Method Thereof

The present invention relates to an ultrasonic fingerprint sensor and a method of manufacturing the same.

Biometrics is a technology that provides a high level of security, and fingerprint technology is one of the important biometric technologies.

In general, fingerprint recognition extracts a specific pattern or feature point (for example, a branching point at which the ridge of the fingerprint branches, a disadvantage of ending the ridge) from a fingerprint image formed by receiving a fingerprint from the user, and a pattern of a pre-stored fingerprint image or It is performed to contrast with the feature point.

The fingerprint sensor for recognizing a user's fingerprint may be manufactured in the form of a module including a peripheral component or a structure, for example, and may be implemented integrally with a physical function key. have.

1 schematically illustrates the configuration of an ultrasonic fingerprint sensor according to the prior art.

Referring to FIG. 1, the ultrasonic fingerprint sensor is in a first direction to be electrically connected to a plurality of piezoelectric rods 100 arranged to form a sensor array, and upper ends of the plurality of piezoelectric rods 100. A plurality of first electrode bars 106 arranged, and a plurality of second electrode bars 108 arranged in a second direction orthogonal to the first direction to be electrically connected to the lower ends of the plurality of piezoelectric rods 100. do.

The depicted reference numeral 102 denotes a shielding layer, which is a protective coating formed on top of the first electrode bar 106 so that the finger is placed in proximity to the sensor array, and reference numeral 104 denotes a sensor array opposite the shielding layer 102. The support is attached to the end of the support for supporting the plurality of piezoelectric rods 100 from the bottom.

Here, the piezoelectric rod 100 is formed of a material having piezo characteristics, for example, PZT (lead zirconate titanate), PST, Quartz, (Pb, Sm) TiO3, PMN (Pb (MgNb) O3 The material may include at least one of) -PT (PbTiO3), PVDF, or PVDF-TrFe.

A voltage having a resonant frequency of an ultrasonic band is applied to the first electrode bar 106 connected to the upper end of the piezoelectric rod 100 and the second electrode bar 108 connected to the lower end of the piezoelectric rod 100 to thereby move the piezoelectric rod 100 up and down. When vibrating, the ultrasonic signal having a predetermined frequency is generated and emitted as illustrated in FIG.

In the state where the finger is not in contact with the shielding layer 102, the ultrasonic signal emitted from the piezoelectric rod 100 does not pass through the interface between the piezoelectric rod 100 and the air and returns to the inside of the piezoelectric rod 100.

However, in the state where the finger is in contact, a part of the emitted ultrasonic signal penetrates the interface between the skin of the finger and the piezoelectric rod 100 and proceeds to the inside of the finger. The pattern can be detected.

However, in the conventional ultrasonic fingerprint sensor, in order to connect the first electrode bar 106 electrically connected to the upper side of each of the piezoelectric rods 100 with an external terminal, wire bonding is performed or a separate substrate is mounted. Since an additional process is required, the process of providing an ultrasonic fingerprint sensor package is complicated and the manufacturing cost increases.

The present invention improves the process of attaching a rigid panel for finger contact on the upper electrode bar, thereby eliminating the process of attaching the dummy panel for forming the sensor array and the process of forming a protective coating for the finger contact position. It is possible to provide an ultrasonic fingerprint sensor and a method of manufacturing the same, which can simplify the manufacturing process.

The present invention forms a via hole electrically conductive with the upper electrode bar so that the upper electrode bar and the lower electrode bar can be connected to the external terminal at the same height, thereby improving the convenience and process efficiency of manufacturing an ultrasonic fingerprint sensor package. It is an object of the present invention to provide an ultrasonic fingerprint sensor and a method of manufacturing the same.

Other objects of the present invention will be readily understood through the following description.

According to an aspect of the present invention, a method of manufacturing an ultrasonic fingerprint sensor, the method comprising: forming a plurality of piezoelectric rods using a plurality of first grooves formed in a predetermined sensor region of a silicon substrate; Forming a plurality of second grooves to function as via holes in an edge region of the silicon substrate previously designated to be positioned outside the sensor region; Forming a plurality of first electrode bars in a first direction, the plurality of first electrode bars being energized with conductive materials formed in corresponding via holes, respectively, and electrically connected to upper ends of the plurality of piezoelectric rods; Attaching a rigid panel to upper surfaces of the plurality of first electrode bars, the silicon substrate, and the piezoelectric rod; Planarizing (CMP) a lower surface of the silicon substrate so that the via holes and lower ends of the plurality of piezoelectric rods are exposed to the outside; Removing the silicon substrate in the sensor region and filling an insulating material in a space from which the silicon substrate is removed; And forming a plurality of second electrode bars in a second direction orthogonal to the first direction so as to be electrically connected to the lower ends of the plurality of piezoelectric rods, and respectively forming electrode parts to conduct electricity to the lower ends of the plurality of via holes. There is provided a method of manufacturing an ultrasonic fingerprint sensor comprising a.

The forming of the plurality of piezoelectric rods may include forming a plurality of first grooves in the sensor region by using a mask in which a sensor array shape is previously patterned; Forming a barrier film in the sensor region; And a predetermined piezoelectric material in the form of powder filled in each of the plurality of first grooves on which the barrier film is formed may be sintered to form a piezoelectric rod.

The ultrasonic fingerprint sensor includes a sensor substrate and a silicon substrate which is in contact with an outer portion of the sensor region and is maintained as an edge region, wherein the edge region is formed to surround all the outer sides of the sensor region, or a side portion of the sensor region. May be formed to expose some.

The width of the edge region where the via hole is formed may be formed relatively thicker than the width of the edge region where the via hole is not formed.

The vertical cross section of the ultrasonic fingerprint sensor may be arranged in the order of the silicon substrate, the insulating material, and the piezoelectric rod on which the via hole is formed.

The rigid panel may be attached using an epoxy resin.

The rigid panel comprises at least one of a glass panel and a plastic panel having a predetermined hardness.

According to another aspect of the present invention, there is provided an ultrasonic fingerprint sensor manufactured by the manufacturing method of the ultrasonic fingerprint sensor described above.

According to still another aspect of the present invention, in an ultrasonic fingerprint sensor, a plurality of piezoelectric rods are arranged to form a sensor array and an insulating material is formed to fill a periphery of each piezoelectric rod, and one of the sides of the sensor region. A piezoelectric layer comprising a silicon substrate in contact with the above to form an edge region; A plurality of first electrode bars disposed in a first direction along an upper surface of the piezoelectric layer; A plurality of second electrode bars disposed in a direction orthogonal to a first direction along a lower surface of the piezoelectric layer; And a rigid panel attached to an upper surface of the piezoelectric layer and an upper portion of the first electrode bar, wherein a plurality of via holes corresponding to each of the plurality of first electrode bars are formed in the edge area. The lower end is provided with an ultrasonic fingerprint sensor, characterized in that the electrode portion is formed.

Other aspects, features, and advantages other than those described above will become apparent from the following drawings, claims, and detailed description of the invention.

According to an embodiment of the present invention, a process of attaching a dummy panel for forming a sensor array and a protective coating on a finger contact position by improving a process of attaching a rigid panel for contacting a finger on an upper electrode bar is performed. Forming process can be omitted, there is an effect that the manufacturing process is simplified.

In addition, by forming a via hole electrically connected to the upper electrode bar, the upper electrode bar and the lower electrode bar can be connected to the external terminal at the same height, thereby increasing the convenience and process efficiency of manufacturing an ultrasonic fingerprint sensor package. There is also an effect.

1 is a view schematically showing the configuration of an ultrasonic fingerprint sensor according to the prior art.

2 is a view for explaining the shape and operation of the piezoelectric rod according to the prior art.

3 is a cross-sectional view of the ultrasonic fingerprint sensor and a plan view of a piezoelectric layer according to an embodiment of the present invention.

4 and 5 are views for explaining a manufacturing process of the ultrasonic fingerprint sensor according to an embodiment of the present invention.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all transformations, equivalents, and substitutes included in the spirit and scope of the present invention. In the following description of the present invention, if it is determined that the detailed description of the related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

If an element such as a layer, region or substrate is described as being on or "onto" another element, the element may be directly above or directly above another element and There may be intermediate or intervening elements. On the other hand, if one element is mentioned as being "directly on" or extending "directly onto" another element, no other intermediate elements are present. In addition, when one element is described as being "connected" or "coupled" to another element, the element may be directly connected to or directly coupled to another element, or an intermediate intervening element may be present. have. On the other hand, when one element is described as being "directly connected" or "directly coupled" to another element, no other intermediate element exists.

"Below" or "above" or "upper" or "lower" or "horizontal" or "lateral" or "vertical" Relative terms such as "vertical" and the like may be used herein to describe a relationship of one element, layer or region to another element, layer or region, as shown in the figures. It is to be understood that these terms are intended to encompass other directions of the device in addition to the orientation depicted in the figures.

In addition, in the description with reference to the accompanying drawings, the same components regardless of reference numerals will be given the same or related reference numerals and redundant description thereof will be omitted. In the following description of the present invention, if it is determined that the detailed description of the related known technology may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

Referring to FIG. 3, the ultrasonic fingerprint sensor may be conveniently divided into a rigid panel layer, a piezoelectric layer, and an electrode layer. Here, the rigid panel layer may include the rigid panel 250, and the piezoelectric layer may be formed of the silicon substrate 210, the piezoelectric rod 230, and the insulating material 255. The electrode layer may include a first electrode bar 245, a second electrode bar 260, and an electrode unit 270.

Specifically, the piezoelectric layer formed by using the silicon substrate 210 is processed so that only the edge region of the silicon substrate 210 is maintained, and the via hole 240 is formed in a plurality of places of the silicon substrate 210 having only the edge region. Each is formed. Each via hole 240 may be formed at a position corresponding to each of the first electrode bars 245 which will be described later.

For convenience of description, a region formed of the piezoelectric rod 230 and the insulating material 255 as a region other than the edge held by the silicon substrate 210 may be referred to as a sensor region. 3B illustrates a case in which the silicon substrate 210 is maintained on all four sides of the edge so as to surround all of the sensor regions. However, the edge 1 is based on the sensor region in consideration of the formation position of the via hole 240. The silicon substrate 210 may be processed to be held only at the side or the two sides.

In the inner region of the piezoelectric layer from which the silicon substrate 210 has been removed, a plurality of piezoelectric rods 230 are arranged to form a sensor array, and the space between the respective piezoelectric rods 230 constituting the sensor array and the outermost piezoelectric layer. The space between the rods 230 and the silicon substrate 210 at the edge is filled with insulating material 255.

As illustrated in FIG. 3A, the piezoelectric layer includes a silicon substrate 210 having a via hole 240 formed in a horizontal direction from a sidewall, an insulating material 255, a piezoelectric rod 230, an insulating material 255, and a piezoelectric material. It is arranged in the order of the rod 230.

The width of the silicon substrate 210 forming the edge of the piezoelectric layer may be sufficient as long as the via hole 240 can be stably formed at an appropriate location. Of course, since the width of the silicon substrate 210 is appropriately determined in the same total area, the size of the sensor array to be formed in the inner space may be adjusted to suit the set purpose.

Also, for example, as shown in FIG. 3B, even when the silicon substrate 210 is maintained on all four sides of the edge so as to surround all the sensor regions, the width of the edge region where the via hole 235 is formed is increased. Naturally, the via hole 235 may be formed relatively thicker than the width of the edge area where the via hole 235 is not formed.

Each piezoelectric rod 230 formed in the shape of a bar or rod having a predetermined length has a piezo characteristic, for example, PZT (lead zirconate titanate), PST, quartz, ( Pb, Sm) TiO 3, PMN (Pb (MgNb) O 3) -PT (PbTiO 3), PVDF, or PVDF-TrFe may be formed of a material including at least one material.

A plurality of first electrode bars 245 arranged in a first direction are formed at upper ends of the piezoelectric layers to be electrically connected to upper ends of the plurality of piezoelectric rods 230 (see FIG. 1). In addition, a plurality of second electrode bars 260 arranged in a second direction orthogonal to the first direction are formed at the lower end of the piezoelectric layer to be electrically connected to the lower ends of the plurality of piezoelectric rods 230. In addition, an electrode unit 270 may be formed at a lower portion of each via hole 240 electrically connected to each of the first electrode bars 245.

As such, since the plurality of electrode portions 270 and the plurality of second electrode bars 260 electrically connected to the plurality of first electrode bars 245 are positioned at the same or substantially the same height, the wire bonding or the like may be used. Each of the first electrode bar 245 and the second electrode bar 260 may be easily connected to an external terminal without an additional process.

When the ultrasonic fingerprint sensor described above is assembled to the module, the second electrode bar 260, the electrode portion 270, and the lower part of the piezoelectric layer are electrically insulated so as to be electrically connected to an external terminal without the risk of an electrical short. Ink (PSR ink) 285 may be applied (PSR).

In addition, the rigid panel 250 is attached to the first electrode bar 245 and the piezoelectric layer using the epoxy resin 280. The rigid panel 250 may be formed of, for example, glass or plastic having a predetermined hardness. The epoxy resin 280 to be used as the adhesive material may be determined as a material having a property of not suppressing vertical vibration of the piezoelectric rod 230.

4 and 5, the photoresist (PR) 215 is coated on the upper surface of the silicon substrate 210 (step (a)), and the exposure and the exposure of the sensor array shape to be fabricated using a mask patterned in advance. Development is carried out (step (b)).

In step (c), an etching (silicon etching) process is performed to dig the first groove to a predetermined depth in order to introduce a predetermined piezoelectric material (for example, PZT, etc.) into the silicon substrate 210. Each groove is formed of a piezoelectric rod 230 as described below. Then, the photoresist coated on the silicon substrate 210 is removed to form a silicon mold.

In step (d), a piezoelectric material in a powder state is filled in each of the plurality of first grooves etched and formed in the silicon substrate 210, and a sintering process is performed. The sintering process is a process in which powders filled by heating to a predetermined temperature are deposited on each bonding surface to form a mass. Here, a passivation process for forming a barrier film 220 for preventing a reaction between the silicon substrate 210 and the piezoelectric material due to the high temperature of the sintering process is preceded before filling the grooves with the piezoelectric material 225 in the powder state. May be

When the sintering process is completed, the chemical mechanical polishing (CMP) to planarize the top surface of the piezoelectric layer in step (e) to fill each groove so that the sintered piezoelectric material 225 is formed into each piezoelectric rod 230. The process is carried out.

In addition, the second groove 235 is formed in the edge region of the silicon substrate 210 in which the piezoelectric rod 230 is formed in step (e). As described below, the second groove 235 is formed to correspond to the position where the plurality of first electrode bars 245 are to be formed, and functions as a via hole 240 electrically connected to the first electrode bars 245. It is to. The second groove 235 may be formed by, for example, the same process as that of the steps (a) to (c) described above.

Subsequently, in step (f), the plurality of plurality of electrodes arranged in the first direction to be electrically connected with the metal film formed in the corresponding second groove 235 and also electrically connected to the upper ends of the plurality of piezoelectric rods 230. The first electrode bar 245 is formed.

The process of forming the first electrode bar includes, for example, a sputtering process of depositing a metal (for example, Au / Ti, etc.) to form an electrode in the via hole 240 and an upper surface of the piezoelectric layer. The thickness of the metal formed in the sputtering process may be increased, and the metal film formed in the via hole 240 may be formed in an electroplating process of increasing the thickness so that the metal film is electrically connected to the first electrode bar 245.

Subsequently, in step (g), the rigid panel 250 is attached to the first electrode bar 245 and the piezoelectric layer using the epoxy resin 280. The rigid panel 250 may be formed of, for example, glass or a plastic having a predetermined hardness, and the epoxy resin 280 has flexibility and does not prevent vertical vibration of the piezoelectric rod 230.

The rigid panel 250 described above is used as a work surface to which a finger is to be touched to receive a fingerprint. Since the rigid panel 250 is attached immediately after the formation of the first electrode bar 245, a process of temporarily attaching the dummy panel for the operation of filling an insulating material between the piezoelectric rods 230 to be described later may be omitted. In addition, there is an advantage that the process of applying a protective coating on the piezoelectric layer after the formation of the second electrode bar 260 can be omitted.

Subsequently, in step (h), a chemical mechanical polishing (CMP) process is performed on the lower surface of the piezoelectric layer so that the lower end of the formed piezoelectric rod 230 and the metal film in the via hole 240 are exposed to the lower portion of the piezoelectric layer. . Step (h) to step (k) to be described later may be performed in a state in which the ultrasonic fingerprint sensor formed in the above-mentioned steps (a) to (g) is inverted.

In step (i), the silicon existing between the piezoelectric rods 230 constituting the sensor array (that is, the silicon existing as a partition between the piezoelectric rods) is removed. In this case, for example, a deep reactive ion etching (DRIE) technique may be used, and a portion of the silicon region located at the edge of the silicon substrate 210 may also be inserted into the insulating material 255 which will be described later. Can be removed.

In step (j), an insulating material filling process is performed in which the insulating material 255 is inserted between the piezoelectric rods 230 and also between the outermost piezoelectric rod 230 and the silicon substrate 210. The insulating material 255 may be a material of a flexible material that does not suppress the piezoelectric rod 230 from vibrating up and down when a voltage having a resonance frequency is applied.

The insulating material filling process may be made of, for example, an insulating material coating on the entire lower surface of the piezoelectric layer, and when the lower end of the piezoelectric rod 230 or the like is covered with the insulating material 255 by coating the insulating material 255 A CMP process may be further performed to expose the rod 230 to the outside.

Thereafter, in step (k), a plurality of second electrode bars 260 arranged in a second direction orthogonal to the first direction are formed to be electrically connected to the lower ends of the plurality of piezoelectric rods 230. In addition, each electrode part 270 is formed to be electrically connected to the exposed metal film through each via hole 240.

As such, the first electrode bar 245 and the second electrode bar 260 are structured to be connected to the external terminal at substantially the same height, so that the convenience and process efficiency of the ultrasonic fingerprint sensor package manufacturing can be achieved. There is this.

In addition, when the generated ultrasonic fingerprint sensor is assembled to the lower part of the second electrode bar 260, the electrode part 270, and the piezoelectric layer, it may be electrically connected to an external terminal without the risk of an electrical short. PSR may be applied to the PSR ink 285.

In addition, while the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art to which the present invention pertains without departing from the spirit and scope of the present invention as set forth in the claims below. It will be understood that various modifications and changes can be made.

Claims

In the manufacturing method of the ultrasonic fingerprint sensor,

Forming a plurality of piezoelectric rods using a plurality of first grooves formed in the sensor region of the silicon substrate, which are previously divided into a sensor region and an edge region outside the sensor region;

Forming a plurality of second grooves to function as via holes in the edge region;

Forming a plurality of first electrode bars in a first direction, the plurality of first electrode bars being energized with conductive materials formed in corresponding via holes, respectively, and electrically connected to upper ends of the plurality of piezoelectric rods;

Attaching a rigid panel to upper surfaces of the plurality of first electrode bars, the silicon substrate, and the piezoelectric rod;

Planarizing (CMP) a lower surface of the silicon substrate so that the via holes and lower ends of the plurality of piezoelectric rods are exposed to the outside;

Removing the silicon substrate in the sensor region and filling an insulating material in a space from which the silicon substrate is removed; And

Forming a plurality of second electrode bars in a second direction orthogonal to the first direction so as to be electrically connected to the lower ends of the plurality of piezoelectric rods, and forming electrode parts so as to energize the lower ends of the plurality of via holes, respectively. Method for producing an ultrasonic fingerprint sensor comprising.
The method of claim 1,

Forming the plurality of piezoelectric rods,

Forming a plurality of first grooves in the sensor area by using a mask in which a sensor array shape is previously patterned;

Forming a barrier film in the sensor region; And

And a predetermined piezoelectric material in the form of powder filled in each of the plurality of first grooves on which the barrier film is formed is sintered to form a piezoelectric rod.
The method of claim 1,

The ultrasonic fingerprint sensor includes a sensor substrate and a silicon substrate in contact with an outer portion of the sensor region and maintained as the edge region.

The edge region may be formed to surround all of the outside of the sensor region, or the side portion of the sensor region is formed to partially expose.
The method of claim 3,

A method of manufacturing an ultrasonic fingerprint sensor, characterized in that the width of the edge region where the via hole is formed is relatively thicker than the width of the edge region where the via hole is not formed.
The method of claim 1,

The horizontal cross section of the ultrasonic fingerprint sensor is a manufacturing method of the ultrasonic fingerprint sensor, characterized in that arranged in the order of the silicon substrate, the insulating material, the piezoelectric rod formed with the via hole.
The method of claim 1,

The rigid panel is a manufacturing method of the ultrasonic fingerprint sensor, characterized in that attached using an epoxy resin.
The method of claim 1,

The rigid panel comprises at least one of a glass panel and a plastic panel having a predetermined hardness.