KR20050020436A - Fingerprint Confirmation Apparatus and Manufacturing Method thereof - Google Patents

Abstract

PURPOSE: A fingerprint recognition device for obtaining a high quality fingerprint image and a manufacturing method thereof are provided to offer the high quality fingerprint image by protecting a fingerprint detecting part from external environment, removing light except the light reflected from a fingerprint, and enhancing collection of the light inputted to a light detecting TFT(Thin Film Transistor). CONSTITUTION: A fingerprint detecting unit(300) includes the first substrate(100) formed with a transparent material, the fingerprint detecting part(180), and the second substrate(200) matched/covered on the first substrate, including a light collecting part(210), and formed with the transparent material. The fingerprint detecting part is arranged on the first substrate and outputs a fingerprint pattern signal by receiving the light reflected according to a fingerprint pattern. The light collecting part collects the light reflected according to the fingerprint pattern. An optical unit(400) emits the light by installing to the back of the first substrate. The fingerprint detecting part includes the light detecting TFT(120), a switching TFT(130), a capacitor, and a sensor line.

Description

Fingerprint identification device and manufacturing method thereof {Fingerprint Confirmation Apparatus and Manufacturing Method}

The present invention relates to a fingerprint recognition device and a manufacturing method thereof, and more particularly, to a fingerprint recognition device for manufacturing a high quality fingerprint image and to protect the fingerprint detection unit for sensing a fingerprint from the external environment.

Generally, cryptographic authentication is used for devices that require security, such as computers and cash machines. However, in case of security by password authentication method, safety accidents occur frequently. Therefore, in recent years, users are demanding more secure security, and thus biometrics such as fingerprint readers are actively developed.

The fingerprint recognition device is an authentication device that checks whether the user is the user by irradiating light on the fingerprint, interpreting the fingerprint image reflected from the fingerprint, and comparing it with the fingerprint of the user previously stored in the database.

There are two types of fingerprint recognition devices, optical and semiconductor. Optical type has the advantage of high quality of fingerprint image, but it is weak in image distortion, difficult to miniaturize and high in price. The semiconductor type can be manufactured inexpensively and compactly due to the increase in production by the CMOS process, but has a disadvantage in that reliability is degraded due to weakness in static electricity or other external environments.

Recently, a fingerprint recognition device using a photosensitive thin film transistor (hereinafter referred to as TFT) has been developed. This is a kind of contact image sensor using a-Si photosensitivity, which has a relatively thin structure and high photosensitivity.

The fingerprint recognition device using TFT analyzes a combination of a fingerprint detection unit that detects the amount of light reflected from the fingerprint and outputs a fingerprint image, an optical unit that emits light from the back of the fingerprint detection unit, and a fingerprint image output from the fingerprint detection unit. And a fingerprint reading unit that matches the fingerprint of the user previously stored in the database.

In the fingerprint sensing unit, a signal line, a light sensing TFT, a switching TFT, and a storage capacitor are formed on a transparent base substrate through which light can pass. A protective film for protecting them is formed on the signal line, the light sensing TFT, the switching TFT, and the storage capacitor.

However, when the signal line, the light sensing TFT, the switching TFT, and the storage capacitor are protected only by the above-described passivation layer, the light sensing TFT and the switching TFT are easily damaged by the pressure and external shock generated when the finger is in close contact with the passivation layer. There is this.

In addition, ionic (Na +, Cl-, etc.) substances secreted from the user's finger may pass through the protective film to contaminate the photosensitive TFT and the switching TFT, and the TFT may be destroyed due to static electricity generated by the friction between the finger and the protective film. There is a problem.

Further, light other than the light incident to the light sensing TFT immediately after being reflected from the fingerprint, that is, the light is reflected back from another part of the fingerprint recognition device after being reflected from the fingerprint pattern and is distorted in the fingerprint image by light incident to the light sensing TFT. There is a problem that occurs.

When the above-mentioned problem occurs, the reliability of the TFT fingerprint reader is degraded.

Accordingly, the present invention has been made in view of such a conventional problem, and an object of the present invention is to protect the fingerprint sensing unit from the external environment, to remove light other than the light reflected from the fingerprint, and to reflect the light incident on the photosensitive TFT by reflecting from the fingerprint. The present invention provides a fingerprint recognition device and a method of manufacturing the same to obtain a high quality fingerprint image by improving the light collecting property.

In order to realize the object of the present invention, the present invention outputs a fingerprint pattern signal by receiving light reflected according to a fingerprint pattern and arranged in a matrix form on a first substrate and a first substrate formed of a transparent material through which light is transmitted. A fingerprint sensing unit comprising a fingerprint sensing unit for collecting a light reflected according to a fingerprint pattern, the fingerprint sensing unit including a second substrate covered to face the first substrate, and an optical unit installed on a rear surface of the first substrate to irradiate light; Provided is a fingerprint recognition device including a unit.

In addition, in order to implement the object of the present invention to form a fingerprint sensing unit including a light recognition TFT, a switching TFT and a storage capacitor on a first substrate formed of a transparent material and a light collecting portion formed on the first substrate and formed of a transparent material And attaching a second substrate to protect the fingerprint sensing unit from an external environment.

According to the present invention, by covering a second substrate formed with a light collecting unit on the first substrate formed with a fingerprint sensing unit to protect the fingerprint sensing unit from an external environment or impact, the light reflected from the fingerprint pattern is collected and incident to the photosensitive TFT, Since the light hit by the side of the substrate and the second substrate is removed, a high quality fingerprint image can be obtained.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Fingerprint reader

1 is a cross-sectional view of a fingerprint recognition device according to the present invention. FIG. 2 is an enlarged cross-sectional view of the fingerprint recognition device shown in FIG. 1.

1 and 2, the fingerprint recognition device 1 includes a fingerprint detection unit 300 and an optical unit 400.

The fingerprint sensing unit 300 is composed of the first substrate 100, the second substrate 200, and the light absorbing part 250 again.

The first substrate 100 is formed of a transparent material through which light can be transmitted, and the fingerprint sensing unit 180 is formed on the first substrate 100.

3 is an equivalent circuit diagram of the fingerprint sensing unit shown in FIG. 2.

The fingerprint sensing unit 180 includes signal lines 110, 112, 114, and 116, a light sensing TFT 120, a switching TFT 130, a storage capacitor 140, and a light blocking layer.

Referring to FIG. 3, the signal lines 110, 112, 114, and 116 include a plurality of first gate lines 110, a plurality of second gate lines 112, a plurality of voltage applying lines 114, and a plurality of sensor lines 116. . The first gate lines 110 are spaced apart from each other and formed long in the first direction of the first substrate 100. The first gate line 110 is applied with a bias voltage that controls the on / off of the photosensitive TFT 120. The second gate lines 112 are formed between the first gate lines 110, and are formed to be elongated in the same direction as the first gate line 110 while being spaced apart from the first gate lines 110. The second gate line 112 applies a gate control signal for turning on / off the switching TFT 130 every frame set to output the sensed fingerprint pattern.

The voltage applying lines 114 are spaced apart from each other and elongated along the second direction of the first substrate 100. The voltage applying line 114 applies a DC voltage V _DD of a predetermined level to the photosensitive TFT 120.

The sensor lines 116 are formed between the voltage applying lines 114 and spaced apart from the voltage applying lines 114 to be formed long in the same direction as the voltage applying lines 114. The sensor lines 116 output the fingerprint pattern signal output from the switching TFT 130 toward the fingerprint reading unit (not shown).

As shown in FIG. 3, the photosensitive TFT 120, the switching TFT 130, and the storage capacitor 140 intersect each other with the first gate line 110, the second gate line 112, and the voltage applying line 114. And inside the sensor lines 116.

2 and 3, the photosensitive TFT 120 is disposed at a portion where the first gate line 110 and the voltage application line 114 cross each other. The photosensitive TFT 120 includes a gate electrode G, a channel layer C, a source electrode S, and a data electrode D. The gate electrode G extends from the first gate line 110 in the direction in which the second gate line 112 is formed. The channel layer C is disposed on the top surface of the gate electrode G in an insulated state from the gate electrode G. A channel layer (C) is preferably made of an amorphous silicon thin film (amorphous silicon film) and an n ⁺ amorphous silicon thin film (n ⁺ amorphous silicon film) disposed on the upper surface of the amorphous silicon thin film. The n ⁺ amorphous silicon thin film is formed in two parts on the surface of the amorphous silicon thin film. The channel layer C thus formed generates photovoltaic power that electrically conducts the source electrode S and the drain electrode D in response to light. The source electrode S extends from the voltage application line 114 in the direction of the sensor line 116. The source electrode S is in contact with one of two divided n ⁺ amorphous silicon thin films. The drain electrode D is in contact with the other one of the n ⁺ amorphous silicon thin films divided into two and is connected to the storage capacitor 140. The photosensitive TFT 120 receives and drives light reflected from the fingerprint pattern.

The switching TFT 130 is disposed at the intersection of the second gate line 112 and the sensor line 116. The switching TFT 130 includes a gate electrode G, a channel layer C, a source electrode S, and a data electrode D. The gate electrode G extends from the second gate line 112 in the direction in which the first gate line 110 is formed. The channel layer C is disposed on the top surface of the gate electrode G in an insulated state from the gate electrode G. The channel layer C preferably consists of an amorphous silicon thin film and an n ⁺ amorphous silicon thin film disposed on the upper surface of the amorphous silicon thin film. The n ⁺ amorphous silicon thin film is formed in two parts on the surface of the amorphous silicon thin film. The source electrode S is in contact with one of two divided n ⁺ amorphous silicon thin films and is connected to the storage capacitor 140. The drain electrode D extends from the sensor line 116 toward the voltage application line 114. The drain electrode D is in contact with the other one of the n ⁺ amorphous silicon thin films divided into two. The switching TFT 130 outputs a voltage proportional to the amount of charge charged in the storage capacitor 140 toward the sensor line 116.

The storage capacitor 140 includes a first electrode 142 and a second electrode 146. The first electrode 142 is connected to the first gate line 110. The second electrode 146 is formed on the first electrode 142 with the gate insulating layer 134 interposed therebetween. The second electrode 146 is connected to the drain electrode D of the photosensitive TFT 120 and the source electrode S of the switching TFT 130. The gate insulating layer 134 disposed between the first electrode 142 and the second electrode 146 serves as a dielectric of the storage capacitor 130. The storage capacitor 130 serves to charge the electric charge in proportion to the amount of light input to the photosensitive TFT 120.

As shown in FIG. 3, the aforementioned four signal lines 110, 112, 114, and 116, one light sensing TFT 120, one switching TFT 130, and one storage capacitor 140 form one unit cell. A plurality of unit cells exist on one substrate 100, and these unit cells are arranged in a matrix form.

The light blocking film 160 is formed at a portion corresponding to the switching TFT 130 with the insulating layer 150 interposed therebetween. The light blocking film 160 prevents light reflected from the fingerprint pattern from entering the channel layer C of the switching TFT 130.

Reference numeral 170 is a protective layer for protecting the photosensitive TFT 120, the switching TFT 130, and the storage capacitor 140.

4 is a perspective view of the second substrate illustrated in FIG. 1.

1, 2, and 4, the second substrate 200 is formed of a transparent material through which light can pass, and has the same size and shape as the first substrate 100. The second substrate 200 is covered on the first substrate 100 to protect the fingerprint detector 180 from an external environment and impact. A condenser 210 is formed on the surface of the second substrate 200 facing the fingerprint detector 180 to condense the light reflected from the fingerprint pattern to improve the light efficiency. The exact position where the light collecting portion 210 is formed is a portion corresponding to each of the light sensing TFTs 120. The light collecting unit 210 is formed as a semi-circular groove to increase the light collecting efficiency.

1 and 2, the light absorbing part 250 is formed on four sides of the first substrate 100 and the second substrate 200 attached to each other. The light absorbing part 250 is formed of a material that absorbs light so that light is not reflected from the side surfaces of the first substrate 100 and the second substrate 200. For example, chromium, chromium oxide, and organic black materials are used. .

The optical unit 400 is installed on the rear surface of the first substrate 100. The optical unit generates light and transmits the light to the fingerprint recognition unit 300.

Referring to the operation of the fingerprint recognition device configured as described above is as follows.

When light is irradiated from the optical unit 400 to the fingerprint detection unit 300, the user's finger is in close contact with the upper surface of the second substrate 200. Then, the light transmitted from the optical unit 400 is reflected according to the fingerprint pattern formed on the finger. At this time, the light is reflected in the mountain part of the fingerprint pattern, and the light is diffusely reflected in the valley part of the fingerprint so that the light is hardly reflected.

Each light reflected by the fingerprint pattern is refracted by the light collecting part 210 formed on the second substrate 200, and the light collected through the refraction is immediately incident on the light sensing TFT 120. In addition, the light reaching the side surfaces of the first substrate 100 and the second substrate 200 after being reflected by the fingerprint pattern is absorbed by the light absorbing unit 250 and is not incident to the photosensitive TFT 120. Therefore, image distortion of the fingerprint pattern hardly occurs.

When light is incident on the photosensitive TFT 120, the photosensitive TFT 120 is driven, and charge is charged in the storage capacitor 140 connected to the photosensitive TFT 120 due to the driving of the photosensitive TFT 120. Here, the charge is charged in the storage capacitor 140 in proportion to the amount of light received by the photosensitive TFT 120.

On the other hand, in order to output the detected fingerprint pattern, a gate control signal is periodically applied to the gate electrode G of the switching TFT 130, and the switching TFT 130 is turned on by this signal. At this time, a voltage proportional to the amount of charge charged in the storage capacitor 140 is output toward the sensor line 116 through the drain electrode D of the switching TFT 130.

Then, the fingerprint pattern signal output from each switching TFT 130 by the fingerprint reading unit connected to the fingerprint recognition device 1 is combined to check the user's identity by comparing with the fingerprint of the user previously stored in the database.

Manufacturing method of fingerprint recognition device

5A to 5I are views for explaining a process of forming a fingerprint sensing unit on a first substrate according to the present invention.

Referring to FIGS. 5A to 5I, a method of manufacturing a fingerprint sensing unit including a light sensing TFT, a switching TFT, and a storage capacitor on a first substrate made of a transparent material will be described below.

 Referring to FIG. 5A, a metal material is deposited on the first substrate 100, and the metal material is patterned to form the first gate electrode 122 and the second gate electrode 132 spaced apart from the first gate electrode by a predetermined distance. Form. Although not shown, when forming the first and second gate electrodes 122 and 132, the first gate line and the second gate line are also formed.

Referring to FIG. 5B, a transparent conductive material, for example, an ITO material, is coated on the first gate electrode 122 and the second gate electrode 132 and then patterned to form the first gate electrode 122 and the second gate electrode. The first electrode 142 of the storage capacitor 140 is formed between the 132. Here, the first electrode 142 is connected to the first gate electrode 122.

5C, an insulating material, for example, silicon nitride (SiN _X ) is coated on the first gate electrode 122, the first electrode 142, and the second gate electrode 132 to form a gate insulating layer. 144 is formed. Here, the gate insulating layer 144 becomes the dielectric of the storage capacitor 140.

As shown in FIG. 5D, amorphous silicon (a-Si) and n ⁺ amorphous silicon are sequentially deposited on the gate insulating layer 144 and patterned to form a first channel at a portion corresponding to the first gate electrode 122. The layer 124 is formed, and the second channel layer 134 is formed in a portion corresponding to the second gate electrode 132.

Next, referring to FIG. 5E, a metal material is deposited on the first channel layer 124 and the second channel layer 124, and patterned to form a first source electrode on the top surface of the first channel layer 124. 126 and the first drain electrode 128 are formed to form a photosensitive TFT. The second source electrode 136 and the second drain electrode 138 are formed on the upper surface of the second channel layer 134 to form a switching TFT. When the source electrodes 126 and 136 and the drain electrodes 128 and 138 are patterned, the central portion of the n ⁺ amorphous silicon film is etched together with the source and drain electrodes and divided into two. Although not shown, the voltage applying line 114 and the sensor line 116 when forming the first source electrode 126 and the first drain electrode 128, the second source electrode 136, and the second drain electrode 138. ) Also form.

Referring to FIG. 5F, a transparent metal material is deposited on the first source electrode 126, the first drain electrode 128, the second source electrode 136, and the second drain electrode 138, and then patterned. A second electrode 146 is formed at a portion corresponding to the electrode 142 to form the storage capacitor 140. The second electrode 146 mutually connects the first drain electrode 128 and the second source electrode 136 to each other. Connect it.

Referring to FIG. 5G, an insulating material is coated on the photosensitive TFT 120, the switching TFT 130, and the storage capacitor 140 to form the insulating layer 150.

Referring to FIG. 5H, chromium / chromium oxide (Cr / Cr _× O _Y ) is deposited on the top surface of the insulating layer 150, and patterned to form a light shielding layer on a portion corresponding to the switching TFT 130. Black Matrix) 160 is formed.

 Finally, referring to FIG. 5I, the photosensitive TFT 120, the switching TFT 130, and the storage capacitor 140 may be formed of silicon nitride on the light blocking layer 160 and the insulating layer 150 to protect the external environment from the external environment. An interlayer insulating layer 170 is formed.

6 is a view for explaining a state in which the second substrate is attached to the first substrate according to the present invention.

When the fingerprint sensing unit 180 is formed on the upper surface of the first substrate 100 in the above-described order, as shown in FIG. 6, the second substrate 200 having the semi-circular condensing portions 210 formed on one surface thereof. And the first substrate 100 are assembled. Then, the second substrate 200 is covered on the first substrate 100 to attach them to each other.

7 is a view for explaining a state in which a light absorbing portion is formed on the side of the fingerprint detection unit.

A light absorbing part 250 is formed by coating chromium, chromium oxide, and an organic black material along side surfaces of the first and second substrates 100 and 200 attached to each other.

As described above in detail, the reliability of the product may be improved by covering the second substrate on which the condenser is formed on the first substrate on which the fingerprint sensing unit is formed to protect the fingerprint sensing unit from an external environment or impact. In addition, since the light reflected from the fingerprint pattern is collected and incident on the photosensitive TFT, the light hit by the side of the first substrate and the second substrate is removed, thereby obtaining a high quality fingerprint image. In the detailed description of the present invention described above with reference to a preferred embodiment of the present invention, those skilled in the art or those skilled in the art having ordinary knowledge in the scope of the invention described in the claims to be described later It will be understood that various modifications and variations can be made in the present invention without departing from the scope of the present invention.

1 is a cross-sectional view of a fingerprint recognition device according to the present invention.

FIG. 2 is an enlarged cross-sectional view of the fingerprint recognition device shown in FIG. 1.

3 is an equivalent circuit diagram of the fingerprint sensing unit shown in FIG. 2.

4 is a perspective view of the second substrate illustrated in FIG. 1.

5A to 5I are views for explaining a process of forming a fingerprint sensing unit on a first substrate according to the present invention.

6 is a view for explaining a state in which the second substrate is attached to the first substrate according to the present invention.

7 is a view for explaining a state in which a light absorbing portion is formed on the side of the fingerprint recognition unit.

Claims (8)

A first substrate formed of a transparent material, a fingerprint sensing unit arranged to form a matrix on the first substrate and receiving light reflected according to a fingerprint pattern to output a fingerprint pattern signal, and condensing the light reflected according to the fingerprint pattern A fingerprint sensing unit having a light collecting part and formed of a transparent material, the fingerprint sensing unit including a second substrate covered to face the first substrate; And And an optical unit provided on a rear surface of the first substrate to irradiate light. The display apparatus of claim 1, wherein the fingerprint sensing unit comprises: a photo sensing TFT configured to receive and drive light reflected according to the fingerprint pattern; A switching TFT connected to the photosensitive TFT and outputting a fingerprint pattern signal provided from the photosensitive TFT; A storage capacitor connected to the photosensitive TFT and the switching TFT to charge a charge in proportion to the amount of light received by the photosensitive TFT; And And a sensor line connected to the switching TFT to output the fingerprint pattern signal. The fingerprint recognition device of claim 2, wherein the condenser is formed on a portion of the surface facing the fingerprint sensing unit corresponding to the light sensing TFT. The fingerprint recognition device according to claim 3, wherein the light collecting portion is a semicircular groove. The fingerprint recognition apparatus of claim 1, further comprising a light absorbing part disposed on a side of the fingerprint sensing unit to absorb light that reaches the side of the fingerprint sensing unit among the light reflected by the fingerprint pattern. The fingerprint recognition device of claim 5, wherein the light absorbing unit is formed by applying chromium, chromium oxide, and an organic black material. Forming a fingerprint sensing unit including a light recognition TFT, a switching TFT, and a storage capacitor on a first substrate formed of a transparent material; And And attaching a second substrate formed of a transparent material on the first substrate to protect the fingerprint detection unit from an external environment. The method of claim 7, further comprising forming a light absorbing part by applying a light absorbing material to side surfaces of the first and second substrates attached to each other.