KR100911460B1 - Fingerprinting device and method for fabricating the same - Google Patents

Abstract

Disclosed are a fingerprint recognition device for improving an aperture ratio and a method of manufacturing the same. The fingerprint reader includes a switching transistor and a sensor transistor. The source electrode of the switch transistor is also used as a gate electrode of the sensor transistor, and the drain electrode of the sensor transistor is also used as a light blocking layer for preventing light from reaching the switch transistor. In addition, the source electrode and the gate electrode of the sensor transistor are electrically connected through a contact hole for exposing a part of the gate electrode of the sensor transistor. According to the fingerprint recognition device and the manufacturing method thereof, the aperture ratio can be increased, and the stability of the fingerprint recognition operation can be improved.

Description

Fingerprint recognition device and manufacturing method thereof {FINGERPRINTING DEVICE AND METHOD FOR FABRICATING THE SAME}

1 is a cross-sectional view showing a cross section of a fingerprint recognition TFT substrate according to the prior art.

2 is a cross-sectional view showing a cross section of a fingerprint recognition TFT substrate according to an embodiment of the present invention.

FIG. 3 is an equivalent circuit diagram of the switching TFT and the sensor TFT of the unit cell of FIG. 2.

4A to 4G are cross-sectional views of the manufacturing process for explaining the manufacturing process of the fingerprint recognition TFT substrate shown in FIG.

* Description of the symbols for the main parts of the drawings *

200: fingerprint recognition TFT substrate 202: transparent substrate

210: switching TFT 230: sensor TFT

408: First source electrode 414: Contact hole

420: second source electrode 422: second drain electrode

The present invention relates to a fingerprint recognition device and a manufacturing method thereof, and more particularly, to a fingerprint recognition device for improving the aperture ratio and a manufacturing method thereof.

The a-Si Thin Film Transistor Liquid Crystal Display (hereinafter referred to as TFT-LCD) is one of flat panel displays (FPDs), and is widely used in notebook computers, monitors, televisions, mobile terminals, and the like. It is used.

Here, the a-Si TFT-LCD has a switching function and is used as a display element. In addition, a-Si TFT-LCD has a photosensitive property that changes chemically upon receiving light, and thus is widely used in the biometrics industry as a light sensing sensor.

The biomatrix industry relates to a personal authentication system that utilizes unique personal features such as fingerprint, voice, face, hand or iris. Here, in the aspect of cost, ease of use, and accuracy, a personal authentication method using a fingerprint is widely used among the unique features of the individual.

Typical fingerprint recognition apparatuses include an optical type using an optical sensor and a semiconductor type using a sensor on a silicon chip substrate.

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. In particular, it is not suitable for a mobile terminal because it is impossible to thin and thin by using a plurality of lenses.

On the other hand, the method of utilizing the CMOS process of the semiconductor type can be miniaturized by manufacturing the CMOS process, but has a disadvantage in that the reliability is poor because it is weak to static electricity or other external environment.                         

As the use of the mobile terminal is gradually increased, the fingerprint recognition device is required to be lightweight, compact, durable and stable to be suitable for the mobile terminal.

Recently, an a-Si TFT fingerprint recognition apparatus that satisfies the requirements for hair has been developed, and high photosensitivity can be obtained with a relatively thin structure.

1 is a cross-sectional view showing a cross section of a fingerprint recognition TFT substrate according to the prior art.

As shown in FIG. 1, the fingerprint recognition TFT substrate according to the related art includes a switching TFT 110, a sensor TFT 130, and a storage capacitor 140 formed on the transparent substrate 100.

Here, the drain electrode 132 of the sensor TFT 130 is connected to the external power supply line Vd, and the source electrode 134 of the sensor TFT 130 and the source electrode 112 of the switching TFT 110 are formed. It is electrically connected via one electrode 142. The drain electrode 114 of the switching TFT 110 is connected to the sensor signal output line Readout. The gate electrode 136 of the sensor TFT 130 is connected to the sensor TFT gate line, and the gate electrode 116 of the switching TFT 110 is connected to the switching TFT gate line. The second electrode 144 is also connected to the sensor TFT gate line.

Since the insulating layer 146 is positioned between the first electrode 142 and the second electrode 144, the first electrode 142 and the second electrode 144 serve as the storage capacitor 140. At this time, the storage capacitor 140 serves to charge the electric charge in proportion to the amount of light input to the sensor TFT 130.                         

A first channel region 118 made of amorphous silicon (a-Si) is formed between the source electrode 112 and the drain electrode 114 of the switching TFT 110, and the source electrode 132 of the sensor TFT 130 is formed. ) And a second channel region 138 made of amorphous silicon is formed between the drain electrode 134 and the drain electrode 134. Here, when a predetermined amount or more of light is received in the second channel region 138, the source electrode 134 and the drain electrode 136 of the sensor TFT 130 are electrically conductive.

In addition, a gate insulating film 120 for insulating is formed on the gate electrode 116 of the switching TFT 110.

Meanwhile, the first passivation layer 150 is formed on the entire surface of the transparent substrate 100 on which the switching TFT 110 and the sensor TFT 130 are formed, and the drain electrode 114 and the source electrode 112 of the switching TFT 110 are formed. A light shielding layer 160 is formed on the top to prevent light from being received. In addition, a second passivation layer 170 is formed on the transparent substrate 100 on which the light blocking layer 160 is formed.

As described above, since the switching TFT and the sensor TFT are configured in one pixel on the fingerprint recognition TFT substrate according to the prior art, the brightness of the screen is remarkably lowered when it is mounted on the hair device because the aperture ratio is lower than that of the general LCD TFT. have.

Accordingly, an object of the present invention is to provide a fingerprint recognition device for improving an aperture ratio.

Another object of the present invention is to provide a method of manufacturing the fingerprint recognition device.

A fingerprint recognition device of the present invention for achieving the above object is a first gate electrode formed in a first region on a transparent substrate; A first gate insulating film formed on the first gate electrode; A first drain electrode formed in a first region on the transparent substrate on which the first gate insulating film is formed; A first source electrode formed in the first region and the second region on the transparent substrate on which the first gate electrode is insulated; A second gate insulating layer formed on the entire surface of the transparent substrate on which the first drain electrode and the first source electrode are formed, and having a contact hole exposing a portion of the second source electrode formed in the second region; A channel layer formed in a second region on the second gate insulating film; A second drain electrode formed in the first region to correspond to the second region, the first drain electrode, and the first source electrode on the transparent substrate on which the channel layer is formed; A second source electrode formed in a second region on the transparent substrate on which the channel layer is formed and connected to the first source electrode through a contact hole; And a storage capacitor formed on the transparent substrate on which the second source electrode is formed. Here, the first source electrode is a gate electrode of the second transistor in the second region.

The first transistor is a switching thin film transistor, the second transistor is a sensor thin film transistor, and the second drain electrode is a light blocking layer that prevents light from reaching the first transistor in the first region.

The method of manufacturing a fingerprint recognition device of the present invention comprises the steps of: forming a first gate electrode in a first area on a transparent substrate; Forming a first gate insulating film on the first gate electrode; Forming a first drain electrode in a first region on the transparent substrate on which the first gate insulating film is formed; Forming a first source electrode in a first region and a second region on the transparent substrate on which the first gate electrode is insulated; Forming an insulating film on an entire surface of the transparent substrate having a contact hole through which a portion of the second source electrode formed in the second region is exposed, and the first drain electrode and the first source electrode formed; Forming a channel layer in a second region on the insulating film; Forming a second drain electrode in the first region to correspond to the second region, the first drain electrode, and the first source electrode on the transparent substrate on which the channel layer is formed; Forming a second source electrode in a second region on the transparent substrate connected to the first source electrode through a contact hole and having a channel layer formed thereon; And forming a storage capacitor on the transparent substrate on which the second source electrode is formed.

According to the fingerprint recognition device and the manufacturing method thereof, the aperture ratio can be increased, and the stability of the fingerprint recognition operation can be improved.

Hereinafter, a fingerprint recognition device according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

2 is a cross-sectional view of a fingerprint recognition TFT substrate according to an embodiment of the present invention, and FIG. 3 is an equivalent circuit diagram of a switching TFT and a sensor TFT of the unit cell of FIG. 2.

2 and 3, the fingerprint recognition TFT substrate 200 according to the present invention includes a switching TFT 210, a sensor TFT 230, and a storage capacitor 240 formed on the transparent substrate 202.

Here, the drain electrode 212 of the switching TFT 210 is connected to the sensor signal output line (Readout), the source electrode 214 of the switching TFT 210 is the gate electrode of the sensor TFT 230 formed on the top Also used as (232). That is, the source electrode 214 of the switching TFT 210 is used as the source electrode of the switching TFT 210 in the switching TFT formation region, and is used as the gate electrode of the sensor TFT 230 in the sensor TFT formation region.

In addition, the contact hole 236 formed when the gate insulating layer 234 of the sensor TFT 230 is deposited electrically connects the gate electrode 232 and the source electrode 238 of the sensor TFT 230. The drain electrode 240 of the sensor TFT 230 is formed to completely cover the first channel layer 216 of the switching TFT 210 to also serve as a light blocking layer.

The drain electrode 240 of the sensor TFT 230 is connected to the external power supply line Vd, and the drain electrode 212 of the switching TFT 210 is connected to the sensor signal output line Readout.

The first electrode 242 and the second electrode 244 serve as a storage capacitor 240 by an insulating layer 246 interposed therebetween, and the second electrode 246 is connected to the sensor TFT gate line. have. Here, the storage capacitor 240 serves to charge the electric charge in proportion to the amount of light input to the sensor TFT 230.

A second channel layer 242 made of amorphous silicon (a-Si) is formed between the source electrode 238 and the drain electrode 240 of the sensor TFT 230. When light having a predetermined amount or more of light is received by the second channel layer 242, the source electrode 238 and the drain electrode 240 of the sensor TFT 230 are electrically connected to each other.

When the user closely attaches the fingerprint of the finger to the fingerprint recognition TFT substrate 200, light generated from a backlight (not shown) or the like below the transparent substrate 202 passes through the liquid crystal layer (not shown) of the TFT LCD panel. Incident on the fingerprint recognition TFT substrate 200.

Light incident on the fingerprint recognition TFT substrate 200 is reflected according to the fingerprint pattern and received by the second channel layer 242 of the sensor TFT 230, and the sensor TFT is received by the light received by the second channel layer 242. 230 is turned on so that the storage capacitor 240 is charged with a charge proportional to the amount of light received.

In addition, the protective layer 250 is formed on the entire surface of the transparent substrate 202 on which the second electrode 244 of the storage capacitor 240 is formed.

Here, the fingerprint recognition principle of the unit cell of the TFT fingerprint recognition substrate will be described in more detail with reference to FIG. 3.

A DC voltage Vd of a predetermined voltage level is applied to the drain terminal D of the sensor TFT 230, and a bias voltage of a predetermined level is applied to the gate terminal G.

The switching TFT 230 receives a gate driving signal applied from a gate driver (not shown) through the gate terminal G to perform a switching operation. Here, the gate driver outputs a gate driving signal for switching the switching TFT 230 every frame set to scan the fingerprint, thereby for each sensor TFT 230 arranged to display an image of the fingerprint input through the TFT fingerprint recognition substrate. Make a scanned frame.

In addition, the drain terminal G of the switching TFT 210 is connected to an amplifying unit (not shown) in an external data reading unit (not shown) through a sensing signal output line (Readout), so that the switching TFT 230 When is turned on, a voltage proportional to the amount of charge charged in the storage capacitor Cst is output. At this time, the signal output from the source terminal S of the sensor TFT 230 is amplified by the amplifying unit, and the signal output terminal of the amplifying unit is connected to a multiplexer (not shown) or the like and output as a single signal.

The manufacturing process of the fingerprint recognition TFT substrate constructed and operated as described above will be described in detail with reference to the accompanying drawings.

4A to 4G are cross-sectional views of the manufacturing process for explaining the manufacturing process of the fingerprint recognition TFT substrate shown in FIG.

Referring to FIG. 4A, a method of sputtering a first metal film (not shown) made of aluminum (Al), chromium (Cr), or molybdenum tungsten (MoW) on a transparent substrate 400 made of glass, quartz, sapphire, or the like After deposition, the metal film is patterned to form a first gate electrode 402. Here, the first gate electrode 402 is a gate electrode of the switching TFT 210.

Subsequently, as illustrated in FIG. 4B, silicon nitride (SiNx) is deposited on a front surface of the transparent substrate 400 on which the first gate electrode 402 is formed, referred to as plasma-enhanced chemical vapor deposition (hereinafter referred to as PECVD). To form a first gate insulating film 404.

An amorphous silicon film (a-Si) and an n + amorphous silicon film are deposited on the first gate insulating layer 404 by PECVD, and the deposited silicon film is patterned to form a first channel layer 406.

Referring to FIG. 4C, after depositing a second metal film (not shown) such as chromium (Cr) on the entire surface of the resultant by a sputtering method, the second metal film is patterned to form a first source electrode 408 and The first drain electrode 410 is formed. Here, the first drain electrode 410 is a drain electrode of the switching TFT 210. Further, the first source electrode 408 is a source electrode of the switching TFT 210 and at the same time a gate electrode of the sensor TFT 230.

That is, the first source electrode 408 is used as a source electrode of the switching TFT 210 in the switching TFT formation region in which the switching TFT 210 is configured, and in the sensing TFT formation region in which the sensor TFT 230 is configured, the sensor TFT. It is used as the gate electrode of 230. In this case, when the first source electrode 408 is used as the gate electrode of the sensor TFT 230 in the sensing TFT formation region, it is referred to as a second gate electrode 412.

Next, referring to FIG. 4D, silicon nitride is deposited on the entire surface of the resultant by PECVD, and patterned to have a contact hole 414 for exposing a part of the second gate electrode 412 of the sensing TFT forming region. A two gate insulating film 416 is formed.

As shown in FIG. 4E, an amorphous silicon film (a-Si) and an n + amorphous silicon film are deposited on the second gate insulating film 416 by a PECVD method, and the patterned silicon film is patterned to form a second channel layer 418. ).

Subsequently, a third metal film (not shown) such as chromium (Cr) is deposited on the entire surface of the transparent substrate 400 on which the second channel layer 418 is formed by a sputtering method, followed by patterning the third metal film. The second source electrode 420 and the second drain electrode 422 are formed. Here, the second drain electrode 422 is formed to completely cover the second insulating layer 416 on the first channel layer 406 and serves to block the first channel layer 406 from exposure of light.                     

In addition, the second source electrode 420 is electrically connected to the second gate electrode 412 through the contact hole 414. Therefore, the voltage Vgs between the gate and the source of the sensor TFT 230 is always kept zero. That is, the operation stability of the fingerprint recognition device is limited by limiting the use area of the photo current generated by the fingerprint to a place where Vgs = 0.

Referring to FIG. 4F, in order to form a lower electrode of the storage capacitor 240, an indium tin oxide (ITO) is stacked on the resultant and then patterned to form a first electrode 424. Subsequently, silicon nitride is deposited on the entire surface of the transparent substrate 400 on which the first electrode 424 is formed to form a first insulating layer 426.

Subsequently, as shown in FIG. 4G, in order to make the upper electrode of the storage capacitor 240, ITO is stacked on the first insulating layer 426 so as to face the first electrode 424 and then patterned to form the second electrode 428. ). Here, the storage capacitor 240 is formed by the first electrode 424, the first insulating layer 426, and the second electrode 428.

In addition, a second insulating film (or passivation film) 430 is formed on the entire surface of the transparent substrate 400 on which the second electrode 428 is formed.

As described above, in the fingerprint recognition device according to the present invention, the source electrode of the switch TFT is also used as the gate electrode of the sensor TFT. In addition, the gate electrode and the source electrode of the sensor TFT are electrically connected to each other by a contact hole generated when the gate insulating film of the sensor TFT is formed.

Therefore, in the present invention, the source electrode of the switch TFT is also used as the gate electrode of the sensor TFT, so that the area occupied by the TFT in one pixel can be reduced, thereby improving the aperture ratio.

In addition, the present invention can maintain the Vgs voltage of the sensor TFT to always 0 as the gate electrode and the source electrode of the sensor TFT is electrically connected through the contact hole, thereby improving the stability of the sensing operation of the fingerprint recognition device There is also.

While the invention has been described with reference to one embodiment, those skilled in the art can variously modify and change the invention without departing from the spirit and scope of the invention as set forth in the claims below. I can understand that.

Claims (6)

A fingerprint recognition device having a first region and a second region in which first and second transistors are formed in one pixel, A first gate electrode formed in the first region on the transparent substrate; A first drain electrode formed in the first region on the transparent substrate where the first gate electrode is insulated; A first gate insulating layer formed on the transparent substrate on which the first gate electrode is formed; A first source electrode formed on the first gate insulating layer corresponding to the first region and the second region; A second gate insulating layer formed on an entire surface of the transparent substrate on which the first drain electrode and the first source electrode are formed and having a contact hole exposing a portion of the second source electrode formed in the second region; A channel layer formed corresponding to the second region on the second gate insulating layer; A second drain electrode formed in the first region so as to correspond to the second region, the first drain electrode, and the first source electrode on the transparent substrate on which the channel layer is formed; A second source electrode formed in the second region on the transparent substrate on which the channel layer is formed and connected to the first source electrode through the contact hole; And A storage capacitor formed on the transparent substrate on which the second source electrode is formed; The first source electrode is a gate electrode of the second transistor in the second region, and the second drain electrode is a light blocking layer which prevents light from reaching the first transistor in the first region. Recognition device. The fingerprint recognition device of claim 1, wherein the first transistor is a switching thin film transistor, and the second transistor is a sensor thin film transistor. delete In the manufacturing method of a fingerprint recognition device having a first region and a second region in which first and second transistors are formed in one pixel, Forming a first gate electrode in the first region formed on the transparent substrate; Forming a first gate insulating film on the transparent substrate on which the first gate electrode is formed; Forming a first drain electrode in the first region on the first gate insulating film; Forming a first source electrode in the first region and the second region on the transparent substrate where the first gate electrode is insulated; Forming a second gate insulating film on an entire surface of the transparent substrate having a contact hole exposing a portion of the second source electrode formed in the second region, wherein the first drain electrode and the first source electrode are formed; Forming a channel layer in the second region on the second gate insulating film; Forming a second drain electrode in the first region to correspond to the second region, the first drain electrode, and the first source electrode on the transparent substrate on which the channel layer is formed; Forming a second source electrode in a second region on the transparent substrate connected to the first source electrode through the contact hole and having the channel layer formed thereon; And Forming a storage capacitor on the transparent substrate on which the second source electrode is formed; And the first source electrode is a gate electrode of the second transistor in the second region. The method of claim 4, wherein the first transistor is a switching thin film transistor, and the second transistor is a sensor thin film transistor. The method of claim 4, wherein the second drain electrode is a light blocking layer that prevents light from reaching the first transistor in the first region.

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