KR101309491B1 - liquid crystal display device and the fabrication method thereof - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device having a poly-Si thin film transistor and a method of manufacturing the same.

According to the present invention, in the process of forming a reflective film on the light shielding film formed under the thin film transistor to crystallize amorphous silicon, the laser energy efficiency is increased by using the reflective characteristic of the reflective film to form grains uniformly and largely to improve the characteristics of the thin film transistor. Let's do it.

Polysilicon, shading film, reflecting film

Description

Liquid crystal display device and its manufacturing method

1 is a graph showing the crystallized grain size according to the energy density of an excimer laser.

Figure 2 is a schematic diagram showing a crystallization method using a conventional excimer laser irradiation device.

3A to 3C are views illustrating a process in which amorphous silicon is crystallized to polysilicon by conventional excimer laser irradiation equipment.

4 is a plan view of a polysilicon layer according to the excimer laser crystallization process of FIGS. 3A to 3C.

5 is a plan view showing one pixel of an array substrate for a liquid crystal display device having a polysilicon thin film transistor according to the present invention;

FIG. 6 is a cross-sectional view taken along line AA ′ of FIG. 5 as a first embodiment according to the present invention. FIG.

7A to 7G are cross-sectional views illustrating a process of forming a polysilicon thin film transistor according to the present invention.

8 is a view showing grains of a polysilicon layer formed according to an excimer laser crystallization process according to the present invention.

9 is a cross-sectional view showing a polysilicon thin film transistor as a second embodiment according to the present invention;

10A to 10D are examples of reflective film uneven patterns of a polysilicon thin film transistor according to a second embodiment of the present invention.

11 is a cross-sectional view showing a polysilicon thin film transistor as a third embodiment according to the present invention.

Description of the Related Art [0002]

100, 200, 300: substrate 103, 203: light shielding film

105, 205: reflecting films 207, 307: uneven pattern

111: gate line 112: data line

113, 213, and 313 gate electrodes 114, 214, and 314 a semiconductor layer

114s, 214s, 314s: source impurity region

114d, 214d, and 314d: drain impurity regions

115a, 215a, 315a: source electrode 115b, 215b, 315b: drain electrode

127a, 127b, 227a, 227b, 327a, 327b: contact hole

121, 221, 321: buffer film 123, 223, 323: gate insulating film

125, 225, 325: interlayer insulating film 131, 231, 331: pixel electrode

303: Metal Pattern

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device having a poly-Si thin film transistor and a method of manufacturing the same.

Recently, with the rapid development of the information society, there is a need for a flat panel display having excellent characteristics such as thinning, light weight, and low power consumption. Among them, a liquid crystal display having excellent color reproducibility, etc. display displays) are being actively developed.

In general, a liquid crystal display device is formed by arranging two substrates on which electric field generating electrodes are formed so that the surfaces on which the two electrodes are formed face each other, inserting a liquid crystal material between the two substrates, and then applying voltage to the two electrodes. It is a device that expresses an image by the transmittance of light that varies depending on the movement of liquid crystal molecules by moving the liquid crystal molecules by an electric field.

The lower substrate of the liquid crystal display includes a thin film transistor that is a switching element. A semiconductor layer used in the thin film transistor is amorphous silicon (a-Si). This is because amorphous silicon can be formed on a large substrate such as a low cost glass substrate at low temperature.

However, a driving circuit is required to drive the thin film transistor using such amorphous silicon. The driving circuit includes a plurality of complementary metal oxide semiconductor (CMOS) devices, and single crystal silicon is used to form such a CMOS device.

Accordingly, the liquid crystal display device is driven by connecting a large scale integration made of single crystal silicon to a thin film transistor array substrate made of amorphous silicon by a method such as tape automated bonding (TAB). However, since the price of the driving circuit is very high, such a liquid crystal display has a disadvantage of high price.

Recently, a liquid crystal display device employing a thin film transistor using polysilicon (poly-Si) has been widely researched and developed. In a liquid crystal display using polysilicon, the thin film transistor and the driving circuit can be formed on the same substrate, and the process is simplified because the process of connecting the thin film transistor and the driving circuit is unnecessary. In addition, polysilicon has a field response mobility of about 100 to 200 times greater than that of amorphous silicon, so it has a fast response speed and excellent stability to temperature and light.

Such polysilicon may be formed by depositing amorphous silicon by direct deposition or by depositing amorphous silicon by plasma enhanced chemical vapor deposition (PECVD) or low pressure chemical vapor deposition (LPCVD). Can be.

Formation of the polysilicon using the amorphous silicon is a solid phase crystallization (SPC) method, metal induced crystallization (MIC) method, and Excimer Laser Annealing (ELA) method, Sequential lateral solidification (SLS).

Among these, the excimer laser annealing (ELA) method is an annealing method using pulsed ultraviolet (UV) called excimer laser as the most widely used crystallization method. Quality amorphous silicon can be formed by annealing the amorphous silicon thin film using an excimer laser. Despite the high melting temperature of the amorphous silicon by the excimer laser, since the heat treatment is performed within a relatively short time, it does not damage the substrate.

Hereinafter, a method of crystallizing amorphous silicon using excimer laser annealing (ELA) will be described.

The excimer laser is irradiated onto the amorphous silicon film to temporarily melt and solidify the silicon film to proceed with crystallization.

At this time, the degree of melting of the amorphous silicon film and the state of crystallization according to it change depending on the energy density of the irradiated laser.

1 is a graph showing crystallized grain size according to energy density of an excimer laser.

As shown in FIG. 1, crystallization of amorphous silicon may be classified into first, second, and third regions according to the intensity of laser energy.

The first region is a partial melting region, in which laser energy is irradiated to the amorphous silicon layer at an intensity such that only the surface of the amorphous silicon layer is melted, and in the first region, the amorphous silicon layer after such irradiation. Partial melting of the surface of the film is performed, and small crystal particles are formed on the surface of the amorphous silicon layer through a solidification process.

The second region is a near-complete melting region, which is a region in which laser energy is irradiated to the extent that the amorphous silicon layer is almost melted by increasing the laser energy intensity than the first region, and small nuclei remaining after melting It is possible to obtain crystal grains grown as seed and grow in comparison with the first region, but it is difficult to obtain uniform crystal grains. Here, the second region is considerably narrower than the first region.

The third region is a complete melting region, which is a region where laser irradiation is performed to increase the laser energy intensity than the second region to melt all the amorphous silicon layers, and solidification proceeds after all of the amorphous silicon layers are melted. Thus, homogeneous nucleation is possible, and after irradiation, a crystalline silicon layer made of fine uniform crystal grains is formed.

In the process of producing polysilicon, the number of irradiation and the overlap ratio of the laser beam are controlled to form uniform and large grains by using the energy density of the second region.

However, many grain boundaries of polysilicon act as barriers to current flow, making it difficult to provide reliable thin film transistor elements.In a plurality of grains, the insulation film is destroyed by collision current and deterioration due to collision between electrons, resulting in product defects. There is a problem that causes.

2 is a schematic view showing a crystallization method using a conventional excimer laser irradiation device.

As shown in FIG. 2, the conventional excimer laser irradiation apparatus 20 includes a laser generator 21 for generating a laser beam and a reflection mirror 23 for reflecting a laser beam emitted through the laser generator 21. ) And a lens unit 25 for focusing the laser reflected by the reflection mirror 23 and reducing the laser beam at a constant ratio.

The laser generating device 21 emits an unprocessed laser beam as an excimer laser, and the emitted laser beam passes through an attenuator to adjust energy level. Thereafter, the substrate 10 is irradiated to the substrate 10 through the reflection mirror 23 and the lens unit 25.

Meanwhile, the buffer film 12 and the amorphous silicon layer 14 are sequentially stacked on the substrate 10.

The substrate 10 on which the amorphous silicon layer 14 is deposited is fixed and moved to an XY stage (not shown), so that the amorphous silicon layer 14 is gradually irradiated by a laser irradiated from the excimer laser irradiation equipment 20. Crystallized into polysilicon (15).

3A to 3C are views illustrating a process in which amorphous silicon is crystallized into polysilicon by conventional excimer laser irradiation equipment, and FIG. 4 is a plan view of a polysilicon layer according to the excimer laser crystallization process of FIGS. 3A to 3C.

Referring to FIG. 3A, a buffer film 12 is formed on a substrate 10, and an amorphous silicon layer 14 is formed on the buffer film 12. The amorphous silicon layer 14 irradiated with a laser at an energy density corresponding to the complete melting proximity region NCM is almost melted to an interface with the buffer film 12 but is not melted at a portion of the interface. Will exist.

In this case, a small amount of amorphous silicon that is not melted at the interface is used as a seed 14a, and as shown in FIGS. 3B and 3C, growth of grains 14b occurs toward the upper molten silicon, thereby forming a polysilicon layer. 15 is formed, and a grain boundary is formed between the grain G and the grain G. FIG.

However, as already described with reference to FIG. 1, the grain size change is very large in accordance with the laser energy density irradiated in crystallization of amorphous silicon by excimer laser annealing (ELA), which proceeds in the complete melting proximity region (NCM). Big.

That is, since the variation in grain size is very large for small energy density changes, the spacing and size uniformity of the grain size are sensitive to the laser energy density irradiated during the excimer laser annealing (ELA) process. It is not constant.

Therefore, as shown in FIG. 4, the size of grain G is not constant due to the growth of grain G into the seed 14a of the amorphous silicon, and the polysilicon layer 15 forming the channel. There will be many grain boundaries.

Therefore, a large number of grain boundaries of the polysilicon layer interfere with the flow of current, so that electrons are scattered in the grain boundaries as the electrons move, so that the field effect mobility is considerably degraded. Generates.

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal display device having a polysilicon thin film transistor which improves the characteristics of the thin film transistor by forming grains uniformly and largely using a light shielding film formed under the thin film transistor.

In addition, an object of the present invention is to provide a method for manufacturing a liquid crystal display device having a polysilicon thin film transistor which can improve energy efficiency and equipment use efficiency while using existing laser irradiation equipment.

In order to achieve the above object, an embodiment of a liquid crystal display device according to the present invention includes a light shielding film formed on a substrate and a reflective film formed on the light shielding film; A buffer film formed on an entire surface of the substrate on which the light blocking film and the reflective film are formed; A semiconductor layer formed on the light blocking film and the reflective film on the buffer film and having source and drain impurity regions formed at both sides thereof; A gate insulating film formed on an entire surface of the substrate including the semiconductor layer; A gate electrode formed on a center of the semiconductor layer on the gate insulating film; And source and drain electrodes electrically connected to the source and drain impurity regions, respectively.

In addition, to achieve the above object, a method of manufacturing a liquid crystal display device according to an embodiment of the present invention, forming a light shielding film on the substrate and a reflective film on the light shielding film; Forming a buffer film on an entire surface of the substrate on which the light shielding film and the reflective film are formed; Forming an amorphous silicon layer on the buffer film; Irradiating the amorphous silicon layer with a laser to form a polysilicon layer; Patterning the polysilicon layer to form a semiconductor layer; Forming a gate insulating film on an entire surface of the substrate including the semiconductor layer; Forming a gate electrode on a center of the semiconductor layer on the gate insulating layer; Implanting impurities into both sides of the semiconductor layer using the gate electrode as a mask to form source and drain impurity regions; And forming source and drain electrodes electrically connected to the source and drain impurity regions, respectively.

In addition, to achieve the above object, another embodiment of the liquid crystal display according to the present invention is formed on a substrate, the metal pattern for blocking the light incident from the lower substrate and reflecting the light incident from the upper substrate and; A buffer film formed on the metal pattern; A polysilicon semiconductor layer formed at the metal pattern position on the buffer layer and having source and drain impurity regions formed at both sides thereof; A gate insulating film formed on an entire surface of the substrate including the polysilicon semiconductor layer; A gate electrode formed on a center of the polysilicon semiconductor layer on the gate insulating film; And source and drain electrodes electrically connected to the source and drain impurity regions, respectively.

In addition, in order to achieve the above object, a method of manufacturing a liquid crystal display device according to another embodiment of the present invention is formed on a substrate, the light incident from the lower substrate is blocked and the light incident from the upper substrate is reflected Forming a metal pattern to be formed; Forming a buffer film on an entire surface of the substrate on which the metal pattern is formed; Forming an amorphous silicon layer on the buffer film; Irradiating the amorphous silicon layer with a laser to form a polysilicon layer; Patterning the polysilicon layer to form a semiconductor layer; Forming a gate insulating film on an entire surface of the substrate including the semiconductor layer; Forming a gate electrode on a center of the semiconductor layer on the gate insulating layer; Implanting impurities into both sides of the semiconductor layer using the gate electrode as a mask to form source and drain impurity regions; And forming source and drain electrodes electrically connected to the source and drain impurity regions, respectively.

Hereinafter, a liquid crystal display device having a polysilicon thin film transistor according to the present invention will be described in detail with reference to the accompanying drawings.

5 is a plan view showing one pixel of an array substrate for a liquid crystal display device having a polysilicon thin film transistor according to the present invention.

As illustrated in FIG. 5, a plurality of array substrates for a liquid crystal display device having a polysilicon thin film transistor according to the present invention are arranged in parallel with each other at regular intervals to define a pixel region P on the substrate. Gate lines 111 are arranged, and the plurality of data lines 112 are disposed at regular intervals in a direction substantially perpendicular to the gate line 111.

In addition, each pixel region P defined by crossing the gate line 111 and the data line 112 is switched by a pixel electrode 131 and a signal of the gate line 111 to be switched by the data line 112. ) Is a thin film transistor (T) that transmits a signal of each of the pixel electrode (131).

A light blocking film 103 is formed under the thin film transistor T.

When the light generated from the backlight light source is irradiated toward the rear surface of the thin film transistor T, the semiconductor layer 114 made of the polysilicon layer is directly exposed to the light, and the semiconductor is caused by the light introduced into the semiconductor layer 114. A carrier is formed in the layer 114, and a leakage current is generated in the thin film transistor T by the carrier.

In order to reduce the leakage current and improve image quality, the light shielding film 103 formed in the lower portion of the semiconductor layer 114 in a wider width than the semiconductor layer 114 is used to directly irradiate light directly onto the semiconductor layer 114. To reduce leakage current and improve image quality.

In addition, when the reflective film 105 is formed on the light shielding film 103 and the semiconductor layer 114 formed on the light shielding film 103 is crystallized by a laser crystallization process, the energy absorption is increased to increase the energy absorption rate of the semiconductor layer 114. The size uniformity of the silicon grain is improved and the grain size is improved to improve the characteristics of the thin film transistor.

The thin film transistor T may include a gate electrode 113 protruding from the gate line 111 along a substrate, a gate insulating layer (not shown) covering the gate line 111, and the gate. A semiconductor layer 114 disposed on the gate insulating layer corresponding to the electrode 113, a source electrode 115a protruding from the data line 112 along the substrate, and disposed on the semiconductor layer 114; The drain electrode 115b is spaced apart from the source electrode 115a by a predetermined distance and disposed on the semiconductor layer 114.

The drain electrode 115b is electrically connected to the pixel electrode 131 through the pixel contact hole 127c.

Although not shown, the color filter substrate bonded to the array substrate may have a black matrix layer having an opening corresponding to the pixel region P and serving as a light blocking function, and for implementing color colors. A red / green / blue (R / G / B) color filter layer and a common electrode for driving a liquid crystal together with the pixel electrode are included. Such an array substrate and a color filter substrate are bonded by a seal material having a predetermined space by a spacer and having a liquid crystal injection hole, and a liquid crystal is formed therebetween to complete the liquid crystal display device.

6 is a cross-sectional view taken along line AA ′ of FIG. 5.

As shown in FIG. 6, the light shielding film 103 formed in the thin film transistor region defined on the substrate 100, the reflective film 105 formed on the light shielding film, the light shielding film 103 and the reflective film 105 may be formed. A gate formed on the entire surface of the substrate 100 including the buffer layer 121 covering the semiconductor layer 114, the semiconductor layer 114 formed on the buffer layer 121 to correspond to the light blocking layer 103, and the semiconductor layer 114. An insulating film 123 is formed. The gate electrode 113 formed on the gate insulating layer 123, the source and drain impurity regions 114s and 114d formed in the semiconductor layer 114 on both sides of the gate electrode 113, and the source. And an interlayer insulating layer 125 formed on the entire surface of the substrate 100 with contact holes 127a and 127b so that the surfaces of the drain impurity regions 114s and 114d are partially exposed, and the contact holes 127a and 127b. A source electrode 115a and a drain electrode 115b are formed to be electrically connected to the source / drain impurity regions 114s and 114d through the substrate.

7A to 7G are cross-sectional views illustrating a process of forming a polysilicon thin film transistor according to the present invention.

As shown in FIGS. 7A and 7B, a metal film having a low light transmittance and a metal film having excellent reflectance are continuously deposited on the substrate 100, and the light shielding film is selectively removed by a photolithography process. (103) and a reflective film 105 on the light shielding film 103 are formed.

Examples of a material that can be used as the light blocking film 103 include molybdenum (Mo), and the like, and the reflective film 105 uses a metal having a light reflection characteristic that is relatively superior to that of the light blocking film 103. Examples of the material that can be used as the reflective film 105 are silver (Ag), aluminum (Al), aluminum-based metal (Al alloy, ex. AlNd), copper (Cu), chromium (Cr), molybdenum (Mo), titanium (Ti) etc. are mentioned.

For example, the reflective film 105 made of aluminum has a reflectance of 92% or more at the time of sputter deposition.

The light blocking film 103 blocks light incident to the lower portion of the substrate 100 to suppress leakage current from the semiconductor layer 114, and the reflective film 105 is in the process of crystallizing the semiconductor layer 114. By reflecting the laser beam incident to the amorphous silicon layer to improve the absorption efficiency of the energy of the laser beam in the amorphous silicon layer it is possible to form a high quality polysilicon layer.

As shown in FIG. 7C, a buffer film 121 made of silicon oxide is formed on the entire surface of the substrate 100 including the light blocking film 103 and the reflective film 105, and on the buffer film 121. An amorphous silicon layer 114a is formed.

As shown in FIG. 7D, the amorphous silicon layer 114a is crystallized by irradiating light such as, for example, an excimer laser, to form a polysilicon layer 114b.

At this time, the excimer laser beam irradiated with the amorphous silicon layer 114a heats and melts the amorphous silicon layer 114a, and the excimer laser passes through the amorphous silicon layer 114a and is reflected from the surface of the reflective film 105 to thereby By irradiating back to the amorphous silicon layer 114a, the amorphous silicon layer 114a is melted to promote growth of grains included in the amorphous silicon layer 114a.

In addition, the excimer laser penetrating the amorphous silicon layer is not only reflected by the reflective film but also exists as latent heat therein, which is radiated as radiant energy after the excimer laser is irradiated.

That is, the excimer laser does not reach only the amorphous silicon layer 114a to melt the amorphous silicon layer 114a, but the laser has a transmission property, so that energy is lost, but the reflective film 105 is lost. The laser is reflected back to the amorphous silicon layer 114a.

Therefore, the amorphous silicon layer 114a is melted by the laser irradiation energy and the laser reflection energy to crystallize and the grain growth is promoted.

Meanwhile, before the crystallization process is performed, dehydrogenation of the amorphous silicon layer 114a is performed. That is, since the amorphous silicon layer formed by the plasma CVD method contains a large amount (about 10%) of hydrogen, the thermal process is performed at a temperature of about 430 ° C. for about 2 hours to remove hydrogen contained in the amorphous silicon layer 114a. do.

Subsequently, as shown in FIG. 7E, excimer laser irradiation proceeds to cause the molten amorphous silicon layer to solidify, and grains of the amorphous silicon layer 114a grow to form a polysilicon layer 114b.

At this time, as the polysilicon layer 114b solidifies, not only the growth of the grains in which the radiant energy generated in the reflective film 105 grows when grains grow, but also the size uniformity of the grains and the size of the grains are improved. Improve.

As shown in FIG. 7F, the polysilicon layer 114b is selectively removed through a photo and etching process to form the semiconductor layer 114 corresponding to the light blocking film 103 and the reflective film 105.

Since the semiconductor layer 114 is formed of a polysilicon layer in which grain of uniform size is grown by the reflection energy and the radiation energy of the reflective film 105 in the excimer laser crystallization process, the channel characteristics are excellent.

As shown in FIG. 7G, the gate insulating film 123 is formed by depositing a silicon nitride film or the like on the entire surface of the substrate 100 including the semiconductor layer 114.

Subsequently, a metal film is deposited on the gate insulating film 123, and the metal film is selectively removed through a photo and etching process to form a gate electrode 113.

Here, the metal film is formed by depositing a conductive metal film such as aluminum (Al), aluminum alloy (AlNd), chromium (Cr), tungsten (W), molybdenum (Mo) by sputtering.

Further, by using the gate electrode 113 as a mask, selectively doping n-type or p-type impurity ions on the entire surface of the substrate 100 to source / drain the semiconductor layer 114 on both sides of the gate electrode 113. Impurity regions 114s and 114d are formed.

In this case, between the source / drain impurity regions 114s and 114d, that is, the lower semiconductor layer 114 corresponding to the gate electrode 113 becomes a channel region.

Subsequently, an interlayer insulating layer 125 is formed on the entire surface of the substrate 100 including the gate electrode 113, and a portion of the source / drain impurity regions 114s and 114d are exposed through photo and etching processes. The interlayer insulating layer 125 and the gate insulating layer 123 are selectively removed to form contact holes 127a and 127b.

In addition, a metal film is deposited on the entire surface of the substrate 100 including the contact holes 127a and 127b, and the source / drain impurities are selectively formed through the contact holes 127a and 127b through the photo and etching process. The source electrode 115a and the drain electrode 115b connected to the regions 114s and 114d are formed.

8 is a view showing grains of a polysilicon layer formed according to an excimer laser crystallization process according to the present invention.

According to the excimer laser crystallization process according to the present invention, the amorphous silicon layer is melted by the irradiation energy of the laser and the reflected energy reflected by the reflecting film, and a small amount of amorphous silicon that is not melted at the interface is seeded. Growth of grain G occurs towards the molten silicon, forming grain boundaries between grains G and G. As shown in FIG. At this time, since the energy is continuously supplied by the radiant energy of the reflective film, the size of the growing grain G is large and uniformly formed.

Therefore, in the excimer laser crystallization process, the size and the degree of crystallization of the grain (G) are improved by improving the energy efficiency of the laser beam, and the laser irradiation time can be reduced by improving the crystallization energy efficiency, thereby reducing the manufacturing time and improving the production yield. You can get the benefits.

In addition, the manufacturing method of the polysilicon liquid crystal display device according to the present invention has an advantage that the manufacturing process of the polysilicon liquid crystal display device is easy and easy to apply since the reflective film is formed on the light shielding film and then proceeds in the existing process order.

9 is a cross-sectional view illustrating a polysilicon thin film transistor as a second embodiment according to the present invention.

Here, since the same parts as those shown in FIG. 6 have been described above, description of specific reference numerals will be omitted.

As shown in FIG. 9, in the polysilicon thin film transistor according to the present invention, a light blocking film 203 is formed on a substrate 200, and a reflective film having an uneven pattern 207 on the light blocking film 203. 205 is formed.

The uneven pattern 207 scatters and reflects the laser irradiated onto the reflective film 205 to uniformly provide the reflected energy to the interface between the buffer film 221 and the semiconductor layer 214 so that the grain grows uniformly.

The light shielding film 203 uses a metal film such as molybdenum (Mo), and the reflective film 205 uses at least a metal having better reflection characteristics than the light shielding film 203, for example, silver (Ag) or aluminum (Al). ), Aluminum alloy (Al alloy, ex. AlNd), copper (Cu), chromium (Cr), molybdenum (Mo), titanium (Ti) and the like.

The light blocking film 203 blocks light emitted from the lower portion of the substrate 200 to block leakage current of the semiconductor layer 214, and the reflective film 205 is subsequently formed in the amorphous silicon crystallization process. It is possible to form a high quality polysilicon layer by minimizing the loss of the laser incident to the laser energy to increase the efficiency of the laser energy, the uneven pattern 207 of the reflective film 205 scatters the reflected laser uniform energy To the semiconductor layer 214.

On the other hand, as another embodiment, the uneven pattern 207 is formed in the light shielding film 203 and by depositing the reflective film 205 on the light shielding film 203 in which the uneven pattern 207 is formed, the uneven pattern in the reflective film 205 207 may be formed.

10A to 10D are examples of reflective film uneven patterns of the polysilicon thin film transistor according to the second embodiment of the present invention.

As shown in FIG. 10A, the uneven pattern 207a of the reflective film 205 may have a semicircular shape in cross section.

As shown in FIG. 10B, the uneven pattern 207b of the reflective film 205 may have a triangular cross-section.

As shown in FIG. 10C, the uneven pattern 207c of the reflective film 205 may have a square or polygonal shape in cross section.

As shown in FIG. 10D, the uneven pattern 207d of the reflective film 205 may have a shape in which cross-sectional shapes of different shapes are mixed.

For example, uneven patterns having different heights may be mixed, uneven patterns having different shapes may be mixed, or overlapping uneven patterns may be formed.

11 is a cross-sectional view illustrating a polysilicon thin film transistor as a third embodiment according to the present invention.

Here, since the same parts as those shown in FIG. 6 have been described above, the description of specific reference numerals will be omitted.

As shown in FIG. 11, the polysilicon thin film transistor according to the present invention is formed on a substrate 300, and a metal pattern for blocking light incident from the lower portion of the substrate and reflecting light incident from the upper portion of the substrate ( 303) is formed.

Optionally, the metal pattern 303 is made of a metal having good reflection characteristics, and an uneven pattern 307 may be formed on the metal pattern 303.

The metal pattern 303 uses a metal having excellent reflection characteristics, for example, silver (Ag), aluminum (Al), aluminum-based metal (Al alloy, ex. AlNd), copper (Cu), chromium (Cr) , Molybdenum (Mo), titanium (Ti) and the like.

The uneven pattern 307 having various shapes may be formed on the upper surface of the metal pattern 303.

Here, the metal pattern 303 not only plays a role of light blocking, but also reflects a laser to reenter the semiconductor layer 314 and emits radiant energy, and scatters a laser during laser reflection, thereby providing a semiconductor with uniform energy. The role of incident on the layer 314 may be simultaneously performed.

Accordingly, the metal pattern 303 blocks light emitted from the lower portion of the substrate 300 to block leakage current of the semiconductor layer, and the metal pattern 303 has good reflection characteristics in a crystallization process of amorphous silicon. By minimizing the loss of the laser incident to the amorphous silicon layer to increase the efficiency of the laser energy, it is possible to form a high quality polysilicon layer, the uneven pattern 307 of the metal pattern 303 is to reflect the reflected laser It is scattered so as to be incident on the semiconductor layer 314 with uniform energy.

As described above, the liquid crystal display device having the polysilicon thin film transistor according to the present invention and a method of manufacturing the same are not limited to the embodiments, and those skilled in the art within the technical idea of the present invention. It is apparent that the deformation and improvement can be made by.

In the liquid crystal display device having the polysilicon thin film transistor according to the present invention, the size of the grain grown by the reflection energy and the radiation energy of the reflection film is large and uniform by providing a reflection film on the light shielding film. There is a first effect of improving the channel characteristics.

In addition, since the laser irradiation time can be reduced by improving the laser crystallization energy efficiency when manufacturing the semiconductor layer of the polysilicon thin film transistor according to the present invention, there is a second effect that the manufacturing time is reduced and the manufacturing yield is improved.

In addition, the manufacturing method of the polysilicon liquid crystal display device according to the present invention has a third effect that is easy and is easy to apply the manufacturing process of the polysilicon liquid crystal display device by forming a reflective film on the light shielding film and then proceeding in the existing process order. .

The present invention reduces the energy lost during laser irradiation to the amorphous silicon layer to maximize energy efficiency and has a fourth effect that can be easily applied to existing laser irradiation processes.

Claims (24)

delete delete delete delete delete delete Forming a light shielding film on the substrate and a reflective film on the light shielding film; Forming a buffer film on an entire surface of the substrate on which the light shielding film and the reflective film are formed; Forming an amorphous silicon layer on the buffer film; Irradiating the amorphous silicon layer with a laser to form a polysilicon layer; Patterning the polysilicon layer to form a semiconductor layer; Forming a gate insulating film on an entire surface of the substrate including the semiconductor layer; Forming a gate electrode on a center of the semiconductor layer on the gate insulating layer; Implanting impurities into both sides of the semiconductor layer using the gate electrode as a mask to form source and drain impurity regions; Forming a source and a drain electrode electrically connected to each of the source and drain impurity regions, The light shielding film or the reflective film is formed in a concave-convex pattern, and the polysilicon layer corresponding to the light shielding film and the reflective film in the polysilicon layer forming step has a larger grain size and a larger grain size than the polysilicon layer at another position. Method of manufacturing the device. 8. The method of claim 7, Forming a reflective film on the light shielding film and the light shielding film, Forming a light shielding film forming material on the substrate; Forming the reflective film forming material on the light shielding film forming material; And selectively etching the light blocking film forming material and the reflective film forming material to form a light blocking film and a reflective film. delete 8. The method of claim 7, And irradiating the amorphous silicon layer with a laser to form a polysilicon layer, wherein the reflective film reflects the laser and reincarnates the amorphous silicon layer. 8. The method of claim 7, And forming a polysilicon layer by irradiating the amorphous silicon layer with a laser, wherein the reflective film radiates radiant energy generated by the laser to the amorphous silicon layer. 8. The method of claim 7, The reflective film is made of a metal selected from silver (Ag), aluminum (Al), aluminum-based metal (Al alloy, ex. AlNd), copper (Cu) and chromium (Cr). 8. The method of claim 7, The reflective film is a method of manufacturing a liquid crystal display device, characterized in that the metal is better reflectance than the light shielding film. delete delete delete delete delete Forming a metal pattern formed on a substrate, the metal pattern blocking light incident from the bottom of the substrate and reflecting light incident from the top of the substrate; Forming a buffer film on an entire surface of the substrate on which the metal pattern is formed; Forming an amorphous silicon layer on the buffer film; Irradiating the amorphous silicon layer with a laser to form a polysilicon layer; Patterning the polysilicon layer to form a semiconductor layer; Forming a gate insulating film on an entire surface of the substrate including the semiconductor layer; Forming a gate electrode on a center of the semiconductor layer on the gate insulating layer; Implanting impurities into both sides of the semiconductor layer using the gate electrode as a mask to form source and drain impurity regions; Forming a source and a drain electrode electrically connected to each of the source and drain impurity regions, The metal pattern may be formed as a concave-convex pattern, and the polysilicon layer corresponding to the metal pattern in the polysilicon layer forming step may have a larger grain size and a larger grain size than the polysilicon layer at another position. Way. delete The method of claim 19, And irradiating the amorphous silicon layer with a laser to form a polysilicon layer, wherein the metal pattern reflects the laser and reenters the amorphous silicon layer. The method of claim 19, And forming a polysilicon layer by irradiating the amorphous silicon layer with a laser, wherein the metal pattern radiates radiant energy generated by the laser to the amorphous silicon layer. The method of claim 19, The metal pattern is any one selected from the group consisting of silver (Ag), aluminum (Al), aluminum-based metal (Al alloy, ex. AlNd), copper (Cu) and chromium (Cr). Method of preparation. delete

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