CN101872779B - Image display system and manufacturing method thereof - Google Patents

Abstract

The present invention discloses an image display system and a manufacturing method thereof. The image display system includes a thin film transistor device, which includes: a substrate having a pixel region, a driving thin film transistor, and a switching thin film transistor. The driving thin film transistor and the switching thin film transistor are respectively located in the pixel region and are arranged on the substrate. The driving thin film transistor includes a polycrystalline silicon active layer and the switching thin film transistor includes an amorphous silicon active layer.

Description

Image display system and manufacturing method thereof

technical field

The present invention relates to a kind of flat panel display technology, particularly relate to a kind of organic light emitting diode (organic light emitting diode, OLED) display and have different electrical characteristics (electricalcharacteristic) thin-film transistor (TFT) device and image display with these TFT devices System and method of manufacture.

Background technique

In recent years, the demand for active matrix flat panel displays, such as active matrix OLED (AMOLED) displays, has increased rapidly. The AMOLED display usually uses a thin film transistor (thin film transistor, TFT) as a switching element in a pixel region and a driving element of a light emitting element. In addition, the peripheral circuit area (ie, the driving circuit area) of the AMOLED display also needs to use a CMOS circuit composed of TFTs.

According to the material used in the active layer, it is divided into amorphous silicon (a-Si) and polysilicon TFT. The manufacturing of amorphous silicon TFT is relatively simple and low in cost, but the active layer of TFT is easy to deteriorate and is not suitable as a driving element of a light emitting element. The current polysilicon TFT is manufactured by low temperature polysilicon (LTPS) process, which has the advantages of high carrier mobility, high integration of driving circuit and low leakage current. However, during the above-mentioned LTPS process, the active layer of the TFT is formed by using a high-power laser crystallization process, so the manufacturing cost is high. Furthermore, due to the uneven output energy of the laser, the driving current of each formed OLED driving TFT is different, which causes the problem of visual defects/mura in the display.

In addition, in the AMOLED display, the electrical characteristics of the switching element in the pixel area need to be different from the driving element of the light emitting element. For example, the driving element needs to have characteristics such as high sub-threshold swing and low threshold voltage (threshold voltage), so as to increase the display gray scale (gray scale) and prolong the life of OLED. However, it is quite difficult to fabricate switching TFTs and driving TFTs with different electrical characteristics in the aforementioned LTPS process.

Contents of the invention

An embodiment of the present invention provides an image display system, including: a thin film transistor device, including: a substrate, a driving thin film transistor, and a switching thin film transistor. The substrate has a pixel area. The driving thin film transistor and the switching thin film transistor are respectively located in the pixel area and arranged on the substrate. Wherein, the driving thin film transistor includes a polysilicon active layer, and the switching thin film transistor includes an amorphous silicon active layer.

Another embodiment of the present invention provides a method for manufacturing an image display system, wherein the system has a thin film transistor device, and the method includes: providing a substrate having a pixel area. A driving thin film transistor and a switching thin film transistor are respectively formed on the pixel area of the substrate. Wherein, the driving thin film transistor includes a polysilicon active layer, and the switch thin film transistor includes an amorphous silicon active layer.

Description of drawings

FIG. 1 shows a schematic plan view of an active matrix organic light emitting diode display;

FIG. 2 shows a schematic circuit diagram of the pixel unit in FIG. 1;

3A to FIG. 3H are schematic cross-sectional views illustrating a manufacturing method of an image display system with thin film transistors according to an embodiment of the present invention; and

FIG. 4 is a block diagram of an image display system according to another embodiment of the present invention.

Explanation of reference signs

10: Display panel 10a: Pixel unit

12: Data line drive circuit 14: Scan line drive circuit

16, 360: switch thin film transistor 18, 350: drive thin film transistor

20: Storage capacitor 22: Light emitting element

100: pixel area 300: substrate

302: buffer layer 304: polysilicon active layer

304a: source/drain region 304b: channel region

306: The first insulating layer 308: Metal layer

308a: first grid electrode 308b: lower electrode

308c: Second grid electrode 309: Heavy ion implantation

310: Second insulating layer 312: Amorphous silicon layer

314: Doped amorphous silicon layer 315, 317: Opening

322: Channel layer 324: Source/drain layer

325: Amorphous silicon active layer 326: First source/drain electrode

328: Upper electrode 330: Second source/drain electrode

400: thin film transistor device 500: flat panel display device

600: input unit 700: electronic device

D1-Dn: data line S1-Sn: scan line

Vdd: voltage source

Detailed ways

The manufacture and use of the embodiments of the present invention are described below. However, it can be easily understood that the examples provided in the present invention are only used to illustrate the making and use of the present invention in a specific way, and are not intended to limit the scope of the present invention.

Please refer to FIG. 1 , which shows a schematic plan view of an active matrix organic light emitting diode (AMOLED) display. The AMOLED display includes: a display panel 10 , a data line driving circuit 12 and a scanning line driving circuit 14 . The display panel 10 has a plurality of pixel units, in order to simplify the drawing, only a single pixel unit 10a is shown here. The data line driving circuit 12 has a plurality of data lines D1 to Dn, and the scan line driving circuit 14 has a plurality of scan lines S1 to Sn. Each pixel unit 10 a is connected to a data line and a scan line (for example, a data line D3 and a scan line S3 ) and arranged in a matrix.

Please refer to FIG. 2 , which shows a schematic circuit diagram of the pixel unit 10 a in FIG. 1 . The pixel unit 10 a includes: a light emitting element 22 , such as an organic light emitting diode (OLED), a thin film transistor device 400 , and a storage capacitor 20 for storing image data. The thin film transistor device 400 includes: a driving thin film transistor (driving TFT) 18 for driving a light emitting element and a switching thin film transistor (switching TFT) 16 for switching the on and off states of the pixel units. In this embodiment, the driving thin film transistor 18 for driving the light emitting element 22 is generally a P-type thin film transistor (PTFT), and the switching thin film transistor 16 is generally an N-type thin film transistor (NTFT). The gate of the switching TFT 16 is connected to the corresponding scan line S3 , the drain is connected to the corresponding data line D3 , and the source is connected to one end of the storage capacitor 20 and the gate of the driving TFT 18 . The other end of the storage capacitor 20 is connected to the source of the driving thin film transistor 18 and connected to the voltage source Vdd. The drain of the driving thin film transistor 18 is connected to the light emitting element 22 .

The image display system and the manufacturing method thereof according to the embodiments of the present invention are described below. FIG. 3H illustrates an image display system according to an embodiment of the present invention, especially an image display system with a thin film transistor device 400 . Embodiments of the present invention fabricate switching thin film transistors (eg, NTFT) and driving thin film transistors (eg, PTFT) for pixel units in the pixel area on the transparent substrate.

The TFT device 400 includes a substrate 300 having a pixel region 100 . The buffer layer 302 can be arbitrarily covered on the substrate 300 to serve as an adhesion layer or a pollution barrier layer between the substrate 300 and the subsequently formed active layer, which can be made of a silicon oxide layer, a silicon nitride layer, or a combination thereof constituted.

The driving thin film transistor 350 is located in the pixel area 100 and disposed on the buffer layer 302 above the substrate 300 for driving a light emitting element (not shown) in the pixel area 100 , such as an organic light emitting diode. The driving thin film transistor 350 has a top gate structure, and includes: a polysilicon active layer 304, a first insulating layer 306 covering the polysilicon active layer 304 as a gate dielectric layer, and a first insulating layer 306 above the polysilicon active layer 304. Gate electrode 308a. The polysilicon active layer 304 includes: a channel region 304b and a pair of source/drain regions 304a separated by the channel region 304b. A pair of first source/drain electrodes 326 on both sides of the first gate electrode 308a are respectively electrically connected to the source/drain region 304a.

The switching thin film transistor 360 is located in the pixel region 100 and disposed on the buffer layer 302 above the substrate 300 for switching the pixel on and off. The switching thin film transistor 360 has a bottom gate structure, and includes: a second gate electrode 308c, a second insulating layer 310 covering the second gate electrode 308c as a gate dielectric layer, and a non-conductive layer above the gate electrode 308. Polysilicon active layer 325 . The non-polysilicon active layer 325 includes: a pair of source/drain layers 324 and a channel layer 322 located between the source/drain layers 324 and the second gate electrode 308c. A pair of second source/drain electrodes 330 on both sides of the non-polysilicon active layer 325 are respectively in contact with the source/drain layer 324 for electrical connection.

The storage capacitor is located in the pixel region 100 and disposed on the buffer layer 302 above the substrate 300 , and is electrically connected to the switching thin film transistor 360 through the second source/drain electrode 330 therein. The storage capacitor includes a lower electrode 308b, an upper electrode 328, and a second insulating layer 310 located between the lower electrode 308b and the upper electrode 328 as a capacitor dielectric layer. In this embodiment, the first gate electrode 308a, the second gate electrode 308c and the lower electrode 308b can be made of the same metal layer, and the first source/drain electrode 326, the second source/drain electrode 330 , and the upper electrode 328 may be composed of the same metal layer.

Next, FIG. 3A to FIG. 3H are schematic cross-sectional views illustrating a manufacturing method of an image display system with a thin film transistor 400 according to an embodiment of the present invention. Referring to FIG. 3A , a substrate 300 having a pixel region 100 is provided. The substrate 300 can be made of glass, quartz or other transparent materials. Next, a buffer layer 302 can be optionally formed on the substrate 300 . Afterwards, an amorphous silicon layer (not shown) is formed on the buffer layer 302 . Next, a crystallization process and a patterning process are performed on it to form a polysilicon active layer 304 . In this embodiment, the polysilicon layer 304 can be crystallized by a non-laser crystallization technique. For example, non-laser crystallization techniques include: solid phase crystallization (solid phase crystallization, SPC), metal induced crystallization (metal induced crystallization, MIC), metal induced lateral crystallization (metal induced lateral crystallization, MILC) , field enhanced metal induced lateral crystallization (FE-MILC), or field enhanced rapid thermal annealing (field enhanced rapid thermal annealing), etc. The various crystallization methods listed here are merely examples, and the present invention is not limited thereto.

Referring to FIG. 3B, a first insulating layer 306 and a metal layer 308 are sequentially formed over the pixel region 100 of the substrate 300 and cover the polysilicon active layer 304, wherein the first insulating layer 306 is used as a gate dielectric layer, and the metal Layer 308 is used to define the gate electrode and the bottom electrode of the capacitor. The first insulating layer 306 can be made of silicon oxide, silicon nitride, or other known gate dielectric materials, and the metal layer 308 can be made of molybdenum (Mo), molybdenum alloy, or other known metal electrode materials.

Referring to FIG. 3C, the metal layer 308 is patterned to form a first gate electrode 308a, a second gate electrode 308c, and a lower electrode 308b on the first insulating layer 306 of the pixel region 100, wherein the first gate electrode 308a It is located on the first insulating layer 306 above the polysilicon active layer 304 . Afterwards, using the first gate electrode 308a as an implant mask, heavy ion implantation (heavy ion implantation) 309 is performed on the polysilicon active layer 304 to form a channel region 304b and a source in the polysilicon active layer 304. The electrode/drain region 304a is, for example, a P-type source/drain region. Here, the polysilicon active layer 304 , the first insulating layer 306 and the first gate electrode 308 a form a driving thin film transistor 350 .

Referring to FIG. 3D, a second insulating layer 310, an amorphous silicon layer 312, and a doped amorphous silicon layer 314 (such as an N-type doped amorphous silicon layer) are sequentially formed on the first insulating layer 306 and cover the The first gate electrode 308a, the second gate electrode 308c, and the lower electrode 308b. The second insulating layer 310 is used as a gate dielectric layer and a capacitor dielectric layer. Furthermore, the second insulating layer 310 can be made of silicon oxide, silicon nitride, or other known gate dielectric materials.

Referring to FIG. 3E, the doped amorphous silicon layer 314 and the underlying amorphous silicon layer 312 are sequentially patterned by known photolithography and etching processes, so that on the second insulating layer 310 above the second gate electrode 308c An amorphous silicon active layer 325 is formed. In this embodiment, the amorphous silicon active layer 325 includes: a source/drain layer 324 formed from the doped amorphous silicon layer 314 and a layer located between the source/drain layer 324 and the second gate electrode 308c The channel layer 322 is formed by the amorphous silicon layer 312 in between.

Referring to FIG. 3F , openings 315 are formed in the second insulating layer 310 on both sides of the first gate electrode 308 a and the underlying first insulating layer 306 to expose the source/drain region 304 a through known photolithography and etching processes. At the same time, an opening 317 is formed in the second insulating layer 310 above the lower electrode 308b to expose a portion of the lower electrode 308b.

Referring to FIG. 3G , a metal layer (not shown) is formed on the second insulating layer 310 to fill the openings 315 and 317 and cover the amorphous silicon active layer 325 . In this embodiment, the material of the metal layer includes: aluminum (Al), molybdenum (Mo), titanium (Ti), or a combination thereof. Next, the metal layer is patterned by photolithography and etching processes to form a pair of first source/drain electrodes 326, an upper electrode 328, and a pair of second source/drain electrodes on the second insulating layer 310, respectively. electrode 330 . The first source/drain electrodes 326 are generally located on both sides of the first gate 308 a and are electrically connected to the corresponding source/drain regions 304 a through the opening 315 in the second insulating layer 310 . The upper electrode 328, the lower second insulating layer 310 and the lower electrode 308b form a storage capacitor. The second source/drain electrodes 330 respectively extend to the upper surface of the amorphous silicon active layer 325 to be electrically connected thereto, and expose part of the source/drain layer 324 . Furthermore, the second source/drain electrode 330 is electrically connected to the lower electrode 308 b of the storage capacitor through the opening 317 in the second insulating layer 310 .

Referring to FIG. 3H , the exposed source/drain layer 324 is removed to form a pair of separated source/drain layers 324 and part of the channel layer 322 is exposed. Here, the amorphous silicon active layer 325 (including a pair of separated source/drain layers 324 and channel layer 322 ), the underlying second insulating layer 310 and the second gate electrode 308c form a switching thin film transistor 360 .

According to the above-mentioned embodiments, since the active layer for driving the thin film transistor is manufactured by using a non-laser crystallization process, the problems of visual defect/uneven light emission of the display can be avoided. Furthermore, since the active layer of the switching TFT is made of amorphous silicon and the active layer of the driving TFT is manufactured by a non-laser crystallization process, compared with using LTPS technology to manufacture the driving TFT and the switching TFT In other words, the electrical characteristics of the driving thin film transistor can be different from those of the switching thin film transistor, and at the same time, the manufacturing cost can be reduced.

4 shows a block diagram of an image display system according to another embodiment of the present invention, which can be implemented in a flat panel display (FPD) device 500 or an electronic device 700, such as a notebook computer, a mobile phone, a digital camera, a personal digital assistant (personal digital assistant, PDA), desktop computer, TV, car monitor, or portable DVD player. The TFT device 400 according to the present invention can be disposed on a flat display device 500, and the flat display device 500 can be an OLED display. In other embodiments, the TFT device 400 can be disposed on the electronic device 700 . As shown in FIG. 4 , the electronic device 700 includes: a flat display device 500 and an input unit 600 . The input unit 600 is coupled to the flat panel display device 500 for providing an input signal (eg, an image signal) to the flat panel display device 500 to generate an image.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make changes and modifications without departing from the spirit and scope of the present invention. Therefore, the present invention The scope of protection shall prevail as defined by the appended claims.

Claims (10)

1. an image display system, comprising:

Thin film transistor device, comprising:

Substrate, has pixel region; And

Drive thin-film transistor and switching thin-film transistor, lay respectively at this pixel region and be arranged on this substrate, wherein this driving thin-film transistor comprises polysilicon active layer, and this switching thin-film transistor comprises amorphous silicon active layer, and wherein this driving thin-film transistor also comprises the first source/drain electrodes that is electrically connected to this polysilicon active layer, and this switching thin-film transistor also comprises the second source/drain electrodes that is electrically connected to this amorphous silicon active layer, wherein this first source/drain electrodes and this second source/drain electrodes are consisted of same metal level.

2. image display system as claimed in claim 1, wherein this driving thin-film transistor also comprises first grid electrode, is positioned at this polysilicon active layer top, and this switching thin-film transistor also comprises second grid electrode, is positioned at this amorphous silicon active layer below.

3. image display system as claimed in claim 1, wherein this amorphous silicon active layer also comprises:

Source/drain regions, contacts with this second source/drain electrodes; And

Between ，Gai source/drain regions, channel region and second grid electrode.

4. image display system as claimed in claim 2, wherein this first grid electrode and this second grid electrode are consisted of same metal level.

5. image display system as claimed in claim 1, also comprises resilient coating, covers this substrate, and is constituted by silicon oxide layer, silicon nitride layer or its.

6. image display system as claimed in claim 1, also comprises:

Flat display apparatus, comprises this thin film transistor device, and wherein this flat display apparatus is organic light emitting diode display.

7. image display system as claimed in claim 6, also comprises electronic installation, and this electronic installation also comprises:

This flat display apparatus; And

Input unit, be coupled to this flat display apparatus, in order to provide, input to this flat display apparatus, make this flat display apparatus show image, wherein this electronic installation comprises notebook computer, mobile phone, digital camera, personal digital assistant, desktop computer, television set, vehicle display or portable DVD player.

8. a manufacture method for image display system, wherein this system has thin film transistor device, and the method comprises:

Substrate is provided, and it has pixel region; And

On this pixel region of this substrate, form respectively and drive thin-film transistor and switching thin-film transistor,

Wherein this driving thin-film transistor comprises polysilicon active layer, and this switching thin-film transistor comprises amorphous silicon active layer, wherein forms this driving thin-film transistor and this switching thin-film transistor and comprises:

On this pixel region of this substrate, form this polysilicon active layer;

In this polysilicon active layer and on this substrate, cover the first insulating barrier;

On this first insulating barrier, form respectively first grid electrode and second grid electrode, wherein this first grid electrode is positioned at this polysilicon active layer top;

On this first grid electrode and this second grid electrode, cover the second insulating barrier;

On this second insulating barrier above this second grid electrode, form this amorphous silicon active layer;

On this second insulating barrier, form metal level; And

This metal level of patterning, to form the first source/drain electrodes and the second source/drain electrodes on this second insulating barrier, and this first source/drain electrodes is electrically connected to this polysilicon active layer via this second insulating barrier, and this second source/drain electrodes is electrically connected to this amorphous silicon active layer.

9. the manufacture method of image display system as claimed in claim 8, wherein this driving thin-film transistor also comprises first grid electrode, be positioned at this polysilicon active layer top, and this switching thin-film transistor also comprises second grid electrode, be positioned at this amorphous silicon active layer below, and this first grid electrode is defined and is formed by metal level with this second grid electrode while.

10. the manufacture method of image display system as claimed in claim 8, wherein this amorphous silicon active layer also comprises:

Source/drain layer, contacts with this second source/drain electrodes; And

Channel layer, between this source/drain layer and this second grid electrode.

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