KR20050049652A - Liquid crystal display device and method of fabricating the same - Google Patents

Abstract

The present invention provides a liquid crystal display device and a method for manufacturing the same, which can prevent a defective driving device of a driving circuit unit.

According to an exemplary embodiment of the present invention, a liquid crystal display device includes: a driving device having a structure in which a plurality of thin film transistors including a channel made of polysilicon are connected to a driving circuit in parallel; And a heat conductive material formed adjacent to the channel between adjacent channels of the driving device to conduct heat generated from the channel.

Description

Liquid crystal display and its manufacturing method {LIQUID CRYSTAL DISPLAY DEVICE AND METHOD OF FABRICATING THE SAME}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device and a manufacturing method thereof capable of preventing a defective driving element of a driving circuit portion.

In general, a liquid crystal display (LCD) displays an image corresponding to a video signal on a liquid crystal panel in which liquid crystal cells are arranged in a matrix by adjusting light transmittance of liquid crystal cells according to a video signal. In this case, a thin film transistor (TFT) is commonly used as a device for switching liquid crystal cells.

The thin film transistor used in the liquid crystal display device uses amorphous silicon or polysilicon as the semiconductor layer. The amorphous silicon thin film transistor has the advantage that the characteristics of the amorphous silicon film are relatively good and the characteristics are stable. However, the amorphous silicon thin film transistor has a disadvantage in that the response speed is low due to low charge mobility. Accordingly, the amorphous silicon thin film transistor has a disadvantage in that it is difficult to apply to a driving device of a high resolution display panel, a gate driver, and a data driver that require fast response speed.

The polysilicon thin film transistor is suitable for a high resolution display panel requiring fast response speed due to high charge mobility, and has the advantage of embedding peripheral driving circuits in the display panel. Accordingly, liquid crystal displays using polysilicon thin film transistors have emerged.

1 is a plan view illustrating a liquid crystal display using a conventional polysilicon thin film transistor.

Referring to FIG. 1, a liquid crystal display using a conventional polysilicon thin film transistor includes an image display unit 96 including a pixel matrix, and a data driver 92 for driving data lines 4 of the image display unit 96. ) And a gate driver 92 for driving the gate lines 2 of the image display unit 96.

In the image display unit 96, liquid crystal cells LC are arranged in a matrix to display an image. Each of the liquid crystal cells LC is a switching element connected to the intersection of the gate line 2 and the data line 4 and is a thin film transistor using polysilicon implanted with N-type impurities. Driven by (30).

The N-type TFT 30 causes the liquid crystal cell LC to charge the video signal from the data line 4, that is, the pixel signal, in response to the scan pulse from the gate line 2. Accordingly, the liquid crystal cell LC adjusts the light transmittance according to the charged pixel signal.

The gate driver 94 drives the gate lines 2 sequentially in the horizontal period for each frame by the gate control signals. The gate driver 94 sequentially turns on the thin film transistors in horizontal line units to connect the data line 4 to the liquid crystal cell.

The data driver 92 samples a plurality of digital data signals every horizontal period and converts them into analog data signals. The data driver 92 supplies an analog data signal to the data lines 4. Accordingly, the liquid crystal cells connected to the turned-on thin film transistors adjust the light transmittance in response to data signals from each of the data lines 4.

The gate driver 94 and the data driver 92 may include driving devices connected in a CMOS structure. The driving element is composed of one large TFT having a large channel width W1 so that a relatively large amount of current can flow for switching of a relatively high voltage. Such a driving device uses polysilicon for a fast response speed.

FIG. 2 is a plan view of the driving device of the driving circuit unit, and FIG. 3 is a cross-sectional view of the driving device of FIG. 2.

2 and 3, a driving device including one thin film transistor is formed by implanting impurities (for example, n + ions or p + ions) formed on the lower substrate 20 with a buffer layer 16 interposed therebetween. The gate electrode 66 formed to overlap the channel region 74C of the active layer 74 with the active layer 74 and the gate insulating film 42 therebetween, the gate electrode 66 and the interlayer insulating film 56. Source / drain electrodes 68 and 70 that are insulated from each other and a protective film 48 formed on the source / drain electrodes 68 and 70 are provided.

The source / drain electrodes 68 and 70 may be a source / drain of the active layer 74 in which predetermined impurities are injected through the source / drain contact holes 84S and 84D passing through the gate insulating layer 42 and the interlayer insulating layer 56. It is in contact with the drain regions 74S and 74D, respectively. The passivation layer 48 is formed on the source / drain electrodes 68 and 70 to protect the driving element.

On the other hand, while the driving device composed of one conventional thin film transistor has an advantage that a relatively large amount of current can flow, a large amount of heat is generated due to the flow of a large amount of current. Accordingly, as shown in FIG. 4, a driving device having a structure in which thin film transistors having a plurality of small channel widths W2 are connected in parallel as a structure capable of cooling the heat generated in the channel 57 is limited.

In the liquid crystal display shown in Fig. 4, the driving elements of the driving circuit section have the sum of the respective channel widths W2 equal to one channel width W1 shown in Fig. 2 (small channel width W2) * number of channels. (n) = one channel width W1} and a thin film transistor having a plurality of channels 77 are connected in parallel. As shown in FIG. 5, heat generated in the channel 77 is gated by the gate insulating film 42 and the interlayer insulating film 56 between the plurality of thin film transistors. Absorbed by the insulating film 42 and the interlayer insulating film 56. However, the material of the gate insulating film 42 and the interlayer insulating film 56, but using an insulating material of SiO _2, such as a low dielectric constant to reduce the value of the parasitic capacitance generated between the electrodes, an insulating material such SiO _2, etc. 1.4 It has a low thermal conductivity of about W / mK. Accordingly, only a part of the heat generated in the channel 77 is conducted to the gate insulating film 42 and the interlayer insulating film 56, and the remaining heat is not conducted. As a result, the channel 77 is deteriorated by the heat remaining in the channel 77, thereby preventing the flow of a desired current or degrading the driving device characteristics, resulting in a failure of the driving device, thereby preventing normal driving of the driving device. A problem arises.

Accordingly, an object of the present invention is to provide a liquid crystal display device and a method of manufacturing the same, which can prevent a defective driving element of a driving circuit portion.

In order to achieve the above objects, a liquid crystal display device according to the present invention includes a drive element having a structure in which a plurality of thin film transistors including a channel made of polysilicon in a drive circuit are connected in parallel; And a heat conductive material formed adjacent to the channel between adjacent channels of the driving device to conduct heat generated from the channel.

The driving device includes an active layer formed to include a plurality of channels formed on a buffer film formed on a substrate; A gate electrode overlapping the active layer with the gate insulating layer interposed therebetween; And a source electrode and a drain electrode contacting the active layer with the gate electrode and the interlayer insulating layer interposed therebetween.

And a hole exposing at least one of the buffer film and the substrate between the adjacent channels.

The thermal conductive material is in contact with the buffer film through the hole and is formed on the front surface of the driving device to protect the driving device.

The thermal conductive material is characterized in that it contains SiNx.

The thermal conductive material is characterized by having a thermal conductivity of about 16 ~ 22W / mK.

According to an aspect of the present invention, there is provided a method of manufacturing a liquid crystal display device, the method including: forming a driving device having a structure in which a plurality of thin film transistors including channels made of polysilicon are connected in parallel to a driving circuit; And forming a thermally conductive material adjacent to the channel and absorbing heat generated from the channel between adjacent channels of the driving device.

The forming of the driving device may include forming an active layer including a plurality of channels on a buffer film formed on a substrate; Forming a gate electrode overlapping the active layer with the gate insulating layer interposed therebetween; And forming a source electrode and a drain electrode in contact with the active layer with the gate electrode and the interlayer insulating layer interposed therebetween.

The forming of the driving device may further include forming a hole exposing at least one of the buffer layer and the substrate between the adjacent channels.

The thermal conductive material is in contact with the buffer film through the hole and is formed on the front surface of the driving device.

The thermal conductive material is characterized in that it contains SiNx.

The thermal conductive material is characterized by having a thermal conductivity of about 16 ~ 22W / mK.

Other objects and advantages of the present invention in addition to the above object will become apparent from the description of the preferred embodiment of the present invention with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to FIGS. 6 to 9E.

FIG. 6 is a plan view illustrating in detail a driving device having a structure in which a plurality of polysilicon thin film transistors formed in a driving circuit part of a liquid crystal display according to the present invention are connected in parallel, and FIG. 7 is driving of the driving circuit part shown in FIG. It is sectional drawing cut along the III-III 'line | wire of an element.

6 and 7, a driving element of a driving circuit part including a plurality of thin film transistors is implanted with impurities, for example, n + ions or p + ions, formed on the lower substrate 120 with a buffer layer 116 interposed therebetween. The gate electrode 166, the gate electrode 166, and the interlayer insulating layer 156 formed to overlap the channel region 174C of the active layer 174 with the active layer 174 and the gate insulating layer 142 interposed therebetween. Source / drain electrodes 168 and 170 that are insulated from each other, and a passivation layer 148 formed on the source / drain electrodes 168 and 710 to protect the driving device.

The source / drain electrodes 168 and 170 are source / drain regions of the active layer 174 implanted with a predetermined impurity through the source / drain contact holes 184S and 184D passing through the gate insulating layer 142 and the interlayer insulating layer 156. 174S, 174D.

The passivation layer 148 is formed on the entire surface of the lower substrate 120 on which the source / drain electrodes 168 and 170 are formed, and passes through the gate insulating layer 142 and the interlayer insulating layer 156 between the channel 177 and the channel 177. It is formed to contact the buffer film 116 through the hole 195. In addition, since the through hole 195 penetrates to the buffer layer 116, the passivation layer 148 may be in contact with the lower substrate 120.

Accordingly, heat generated in the channel 177 is absorbed by the protective film 148 and radiated to the outside of the driving device, thereby preventing damage to the driving device of the driving circuit unit such as deterioration of the channel 177.

In detail, the driving device of the driving circuit unit includes a plurality of thin film transistors having a small channel width W2 so that a relatively large amount of current can flow for switching of a relatively high voltage. When the driving circuit is driven to flow a large amount of current through the channel 177 of the driving device, heat is generated in the channel 177. At this time, a protective film 148 is formed between the channel 177 and the channel 177 using an insulating material such as SiNx having a high thermal conductivity of about 16 to 22 W / mK, so that the heat generated in the channel 177 is protected. After heat conduction, heat is radiated to the outside of the driving element. As described above, heat generated in the channel 177 is radiated through the passivation layer 148, thereby preventing the defect of the driving device of the driving circuit unit such that current flows smoothly and the driving device characteristics are maintained.

8A to 9E are plan views and cross-sectional views illustrating a method of manufacturing a driving device of the driving circuit unit shown in FIGS. 6 and 7.

First, a buffer layer 116 is formed by depositing and patterning an entire surface of the lower substrate 120 with an insulating material such as SiO ₂ . After the amorphous silicon film is deposited on the lower substrate 120 on which the buffer film 116 is formed, the amorphous silicon film is crystallized by a laser to form a polysilicon film, and the polysilicon film is patterned by a photolithography process and an etching process using a mask. do. Accordingly, as shown in FIGS. 8A and 9A, an active layer 174 including a plurality of channels is formed.

The gate insulating layer 142 is formed by depositing an insulating material of SiO ₂ on the lower substrate 120 on which the active layer 174 is formed. After the gate metal layer is entirely deposited on the lower substrate 120 on which the gate insulating layer 142 is formed, the gate electrode 166 is formed by patterning the gate metal layer by a photolithography process and an etching process using a mask. Here, an aluminum-based metal including aluminum (Al), aluminum / nedium (Al / Nd), or the like is used as the gate metal layer. Using the gate electrode 166 as a mask, n-ions are implanted into the active layer 174 so that the active layer 174 overlapping with the gate electrode 166 is a channel region 174C. The non-overlapping active layer 174 is formed of the LDD region 74L.

Then, after the photoresist is entirely deposited on the lower substrate 120, the photoresist is patterned by a photolithography process using a mask to form a photoresist pattern. The photoresist pattern is formed so that the LDD region of the active layer 174 is exposed. Using the photoresist pattern as a mask, n + ions or p + ions are implanted into the active layer 174 to form the source region 174S and the drain region 174D of the active layer 174 as shown in FIGS. 8B and 9B. Is formed.

An interlayer insulating film 156 is formed by depositing an insulating material such as SiO ₂ on the lower substrate 120 on which the active layer 174 implanted with n + ions or p + ions is deposited. Thereafter, the interlayer insulating film 156 and the gate insulating film 142 are patterned by a photolithography process and an etching process using a mask. Accordingly, as shown in FIGS. 8C and 9C, the source contact hole 184S and the drain contact hole 184D exposing the source region 174S and the drain region 174D, respectively, are formed, and the channel 177 and the channel are formed. Through holes 195 are formed between the gates 177 and the interlayer insulating layer 156 to expose the buffer layer 116.

After the data metal layer is entirely deposited on the lower substrate 120 on which the source contact hole 184S, the drain contact hole 184D, and the through hole 195 are formed, the data metal layer is formed by a photolithography process and an etching process using a mask. Is patterned. Accordingly, the source and drain electrodes 168 and 170 are formed as shown in FIGS. 8D and 9D. The source and drain electrodes 168 and 170 contact the source region 174S and the drain region 174D of the active layer 174 through the source contact hole 184S and the contact hole 184D of the drain.

An insulating material such as SiNx having a thermal conductivity of about 16 to 22 W / mK is deposited on the lower substrate 120 on which the source and drain electrodes 168 and 170 are formed, thereby buffering through the through holes 195 as shown in FIG. 9E. A protective film 148 is formed in contact with the film 116.

As described above, in the liquid crystal display and the manufacturing method thereof according to the present invention, a protective film 148 having high thermal conductivity is formed between the channel 177 and the channel 177 in the driving element of the driving circuit. Accordingly, the heat generated by the excessive current flow in the channel 177 is conducted through the passivation layer 148, and then radiates to the outside of the driving element, thereby preventing deterioration of the channel 177. As a result, it is possible to prevent the failure of the driving element such as the flow of the current passing through the channel 177 is smooth and the characteristics of the driving element of the driving circuit part are maintained.

On the other hand, the structure in which a protective film with a high thermal conductivity is formed between the channel and the channel can be easily applied to any driving device requiring a wide channel width for switching a relatively high voltage such as an output buffer of the driving circuit portion.

As described above, the liquid crystal display device and the method of manufacturing the same according to the present invention form a protective film having a high thermal conductivity between the channel and the channel in the driving element of the driving circuit, thereby easily dissipating heat generated in the channel. Accordingly, deterioration of the channel is prevented, so that the current flows smoothly, and the driving device defects can be prevented, such as maintaining the characteristics of the driving device.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

1 is a plan view schematically showing the configuration of a conventional liquid crystal display device.

FIG. 2 is a plan view illustrating a driving device including one thin film transistor formed in a driving circuit of a conventional liquid crystal display device.

3 is a cross-sectional view taken along the line II ′ of the driving device of the driving circuit unit shown in FIG. 2.

4 is a plan view illustrating a driving device including a plurality of thin film transistors formed in a driving circuit of a liquid crystal display device.

FIG. 5 is a cross-sectional view taken along the line II-II 'of the driving device shown in FIG. 4.

6 is a plan view illustrating a driving device having a structure in which a plurality of thin film transistors are connected in parallel to a driving circuit of a liquid crystal display according to an exemplary embodiment of the present invention.

FIG. 7 is a cross-sectional view of the driving circuit of the LCD shown in FIG. 6 taken along line III-III ′ of the driving device.

8A to 9F are plan views and cross-sectional views illustrating a method of manufacturing a driving device in the driving circuit shown in FIG. 6.

<Description of Symbols for Main Parts of Drawings>

56,156: gate electrode 52,152: gate line

60,160: source electrode 72,172; Source electrode

74,174: active layer 48, 148: protective film

195: through hole

Claims (12)

A driving device having a structure in which a plurality of thin film transistors including a channel made of polysilicon in a driving circuit are connected in parallel; And a heat conductive material formed adjacent to the channel between adjacent channels of the driving element to conduct heat generated from the channel. The method of claim 1, The driving device An active layer formed to include a plurality of channels formed on the buffer film formed on the substrate; A gate electrode overlapping the active layer with the gate insulating layer interposed therebetween; And a source electrode and a drain electrode contacting the active layer with the gate electrode and the interlayer insulating layer interposed therebetween. The method of claim 2, And a hole for exposing at least one of the buffer film and the substrate between the adjacent channels. The method of claim 3, wherein And the thermal conductive material is in contact with the buffer layer through the hole and formed on the front surface of the driving element to protect the driving element. The method of claim 1, Wherein the thermally conductive material comprises SiNx. The method of claim 1, The thermal conductive material has a thermal conductivity of about 16 ~ 22W / mK. Forming a driving device having a structure in which a plurality of thin film transistors including channels made of polysilicon are connected to the driving circuit in parallel; And forming a thermally conductive material adjacent to the channel and absorbing heat generated from the channel between adjacent channels of the driving device. The method of claim 7, wherein Forming the driving device Forming an active layer including a plurality of channels on a buffer film formed on the substrate; Forming a gate electrode overlapping the active layer with the gate insulating layer interposed therebetween; And forming a source electrode and a drain electrode in contact with the active layer with the gate electrode and the interlayer insulating layer interposed therebetween. The method of claim 8, Forming the driving device And forming a hole exposing at least one of the buffer film and the substrate between the adjacent channels. The method of claim 9, And the thermally conductive material is in contact with the buffer layer through the hole and is formed on the front surface of the driving element. The method of claim 7, wherein The thermally conductive material comprises a SiNx manufacturing method of the liquid crystal display device. The method of claim 7, wherein The thermal conductive material has a thermal conductivity of about 16 ~ 22W / mK manufacturing method of the liquid crystal display device.