KR20050001253A - Method fabricating liquid crystal display device - Google Patents

Abstract

PURPOSE: A method for fabricating an LCD device is provided to simplify process steps and reduce the fabricating cost by forming an LDD(lightly doped drain) region and an active pattern using a stopper as a mask. CONSTITUTION: A method for fabricating an LCD device includes the steps of preparing a substrate(110), forming a gate electrode on the substrate, forming a first insulating layer(115a) on the substrate, forming a semiconductor layer on the substrate, in which a first region, a second region and a channel region are defined, forming a photoresist pattern(150) and a stopper pattern(170) on the channel region, implanting heavily doped impurities into the first region using the photoresist pattern and the stopper pattern as masks, partially removing the photoresist pattern, implanting lightly doped impurities into the second region using the photoresist pattern(150a) partially removed as a mask, forming source/drain electrodes(122a,123a) on the semiconductor substrate, patterning the semiconductor substrate using the stopper pattern and the source/drain electrodes as masks, forming a second insulating layer including a contact hole on the substrate, and forming a pixel electrode connected with the drain electrode through the contact hole.

Description

Manufacturing method of liquid crystal display device {METHOD FABRICATING LIQUID CRYSTAL DISPLAY DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a liquid crystal display device, and more particularly, to a method for manufacturing a liquid crystal display (LCD) with a drive circuit having an improved manufacturing process using a stopper as a mask.

Recently, with increasing interest in information display and increasing demand for using a portable information carrier, a lightweight flat panel display (FPD), which replaces a conventional display device, a cathode ray tube (CRT), is used. The research and commercialization of Korea is focused on. In particular, the liquid crystal display (LCD) of the flat panel display device is an image representing the image using the optical anisotropy of the liquid crystal, is excellent in resolution, color display and image quality, and is actively applied to notebooks or desktop monitors have.

The active matrix (AM) method, which is a driving method mainly used in a liquid crystal display device, is a method of driving a liquid crystal in a pixel part by using an amorphous silicon thin film transistor (a-Si TFT) as a switching element. .

Amorphous silicon thin film transistor technology was established in 1979 by LeComber et al., UK, and commercialized as a 3 "liquid crystal portable television in 1986. Recently, a large area thin film transistor liquid crystal display device of 50" or more has been developed. In particular, the amorphous silicon thin film transistor has been actively used because it is possible to use a low-cost insulating substrate to enable a low temperature process.

However, the electrical mobility (˜1 cm ² / Vsec) of the amorphous silicon thin film transistor is limited to use in peripheral circuits requiring high-speed operation of 1 MHz or more. As a result, studies are being actively conducted to simultaneously integrate the pixel portion and the driving circuit portion on a glass substrate by using a polycrystalline silicon (poly-Si) thin film transistor having a larger field effect mobility than the amorphous silicon thin film transistor. It's going on.

Polycrystalline silicon thin film transistor technology has been applied to small modules such as camcorders since liquid crystal color television was developed in 1982, and has the advantage of being able to manufacture driving circuits directly on the board because of its low sensitivity and high field effect mobility. .

Increasing the mobility may improve the operating frequency of the driving circuit unit that determines the number of driving pixels, thereby facilitating high definition of the display device. In addition, due to the reduction in the charging time of the signal voltage of the pixel portion, the distortion of the transmission signal may be reduced, thereby improving image quality.

In addition, the polycrystalline silicon thin film transistor can be driven at less than 10V compared to the amorphous silicon thin film transistor having a high driving voltage (˜25V) has the advantage that the power consumption can be reduced.

Hereinafter, the driving circuit integrated liquid crystal display will be described in detail.

1 is a plan view showing an array substrate of a general liquid crystal display device, and shows a drive circuit-integrated liquid crystal display device having a drive circuit portion in a substrate on which a pixel portion is formed.

As shown in the drawing, the array substrate 10 includes a pixel portion 20, which is a pixel region in which unit pixels are arranged in a matrix form, a gate driving circuit portion 30a and a data driving circuit portion located outside the pixel portion 20. It consists of the drive circuit part 30 comprised by 30b.

A plurality of gate wires 16 connected to the gate driving circuit unit 30a and a plurality of data wires 17 connected to the data driving circuit unit 30b intersect each other in the pixel unit 20, and the plurality of intersecting regions are formed. A plurality of pixel electrodes 18 are formed on the pixel region.

In addition, the pixel unit 20 is composed of a thin film transistor (not shown) that is a switching device that applies and cuts off a signal voltage to the pixel electrode 18. The thin film transistor is a kind of electric field that controls the flow of current by an electric field. Field Effect Transistors (FETs).

The gate driving circuit unit 30a and the data driving circuit unit 30b use a thin film transistor having a complementary metal oxide semiconductor (CMOS) structure, which is an inverter, in order to properly output an input signal.

In addition, the gate driving circuit unit 30a and the data driving circuit unit 30b are devices for supplying a scan signal and a data signal to the pixel electrode 18 through the gate line 16 and the data line 17, respectively. In addition, the gate driving circuit unit 30a and the data driving circuit unit 30b are connected to an external signal input terminal (not shown) to adjust an external signal input through the external signal input terminal to output to the pixel electrode 18. Play a role.

The CMOS is a type of integrated circuit having a MOS structure used for a thin film transistor of a driving circuit part requiring high speed signal processing, and requires a transistor of P-channel and N-channel, and the characteristics of speed and density are intermediate between NMOS and PMOS. Indicates.

As such, the driving circuit-integrated liquid crystal display device using the polycrystalline silicon thin film has advantages of excellent device characteristics, excellent image quality, high definition, and low power consumption.

However, since the N-type thin film transistor and the P-type thin film transistor must be formed together on the same substrate, the driving circuit-integrated liquid crystal display device has a higher manufacturing process than an amorphous silicon thin film transistor liquid crystal display device forming only a single type channel. There was a disadvantage of being complicated. In general, a liquid crystal display device using a polycrystalline silicon thin film may be manufactured using seven to nine masks including manufacturing a thin film transistor of a driving circuit unit.

The mask process refers to a photolithography process including photoresist coating, exposure, and development. As the number of masks used is increased, manufacturing cost and processing time increase. As a result, there is a problem that the production yield is lowered and the probability of generating a defect in the formed thin film transistor is increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a manufacturing method of a liquid crystal display device with integrated driving circuit which simplifies the manufacturing process and reduces the manufacturing cost by forming an LED area and an active pattern using a stopper as a mask. There is this.

1 is a plan view schematically showing an array substrate of a general liquid crystal display device.

2A through 2K are flowcharts illustrating a manufacturing process of a driving circuit-integrated liquid crystal display device according to an exemplary embodiment of the present invention.

** Explanation of symbols for main parts of drawings **

122a: source region 123a: drain region

122L, 123L: LED area 140a: amorphous silicon thin film

140b: polycrystalline silicon thin film 150150a: photoresist

170: stopper

In order to achieve the above object, the manufacturing method of the liquid crystal display device of the present invention comprises the steps of providing a substrate, forming a gate electrode on the substrate, forming a first insulating film on the substrate, a first on the substrate Forming a semiconductor layer defining a region, a second region, and a channel region, forming a photoresist pattern and a stopper pattern on the channel region, and using the photoresist pattern and the stopper pattern as masks to form a high concentration in the first region Implanting an impurity, removing a portion of the photoresist pattern, implanting a low concentration of impurity into a second region using the photoresist pattern from which the portion is removed, and source / drain electrodes on the semiconductor layer Forming a semiconductor layer by using the stopper pattern and a source / drain electrode as a mask Step, and a step of using the stage and the contact hole to form a second insulating film including a contact hole on the substrate forms a pixel electrode connected to the drain electrode.

In addition, the method of manufacturing the driving circuit-integrated liquid crystal display device of the present invention includes providing a first substrate divided into a pixel portion and a driving circuit portion, and forming a gate electrode on the substrate. Forming a first insulating film on the substrate, and forming a first semiconductor layer including a first region, a second region, and a channel region on the pixel portion on the substrate, and including the first region, the second region, and the channel region. Forming a third semiconductor layer including a second semiconductor layer and a first region and a channel region in a driving circuit portion on the substrate, implanting impurities into the semiconductor layer using a photoresist pattern and a stopper pattern as a mask; Forming a source / drain electrode on the semiconductor layer, patterning the semiconductor layer using the stopper pattern and the source / drain electrode as a mask, forming a second insulating film including a contact hole on the substrate, and forming the contact; Forming a pixel electrode connected to the drain electrode of the first semiconductor layer through the hole.

Hereinafter, the present invention will be described in detail.

In general, a polycrystalline silicon thin film transistor using a polycrystalline silicon thin film as a channel layer of a device is formed in a coplanar structure in which a gate electrode and a source / drain electrode are located together on one side of the channel layer.

The polycrystalline silicon thin film transistor of the coplanar structure requires a large number of mask processes, that is, photolithography process, compared to an amorphous silicon thin film transistor formed of a staggered structure, thereby increasing manufacturing processes and costs. Has a problem.

The staggered structure may be further classified into a back channel etch (BCE) type and an etch stopper (ES) type, among which a thin film transistor manufactured by an etch stopper type has excellent characteristics. It has the advantage of forming a thin silicon film of the channel layer.

In particular, since the thickness of the channel layer must be thin (˜500 kV) for the purpose of reducing the leakage current, the etch-stopper type is more advantageous for the fabrication of the polycrystalline silicon thin film transistor.

Therefore, in the present invention, a thin film transistor of the pixel portion and the driving circuit portion is formed in a staggered structure, but the LED region and the active pattern are formed using the stopper as a mask, thereby reducing the manufacturing process and the cost. to provide.

Hereinafter, with reference to the accompanying drawings will be described a preferred embodiment of the liquid crystal display device manufacturing method according to the present invention.

2A to 2K are flowcharts illustrating a manufacturing process of a driving circuit-integrated liquid crystal display device according to an exemplary embodiment of the present invention, which illustrates a method of manufacturing a thin film transistor of a pixel portion and a driving circuit portion.

For reference, the same reference numerals are used for the same elements as those of the pixel unit and the driving circuit unit.

As shown in FIG. 2A, the array substrate 110 includes a pixel portion in which N-type thin film transistors are formed and a driving circuit portion in which N-type and P-type thin film transistors are formed.

First, a buffer layer 114 composed of a silicon oxide film SiO ₂ is formed on a substrate 110 made of a transparent insulating material such as glass. The buffer layer 114 serves to block impurities such as Na present in the glass substrate 110 from penetrating into the upper layer.

Next, as shown in FIG. 2B, a gate electrode 121 made of molybdenum (Mo) or aluminum (Al) alloy or the like is formed on the buffer layer 114. The gate electrode 121 is formed using a photolithography process after depositing a gate metal on the entire surface of the substrate 110 on which the buffer layer 114 is formed.

The photolithography process is a series of processes in which a pattern drawn on a mask is transferred onto a substrate on which a thin film is deposited to form a desired pattern, and includes a photoresist coating, exposure, and development process.

At this time, the etching of the gate metal may be either wet etching or dry etching, but it is advantageous to use wet etching having isotropic etching characteristics. This is because by using wet etching, a tapered gate electrode can be formed to prevent the short circuit of other films formed on the gate electrode.

As illustrated in FIG. 2C, the first insulating film 115a and the amorphous silicon thin film 140a, which are gate insulating films, are deposited on the entire surface of the substrate on which the gate electrode 121 is formed.

The first insulating film 115a may be formed of a silicon oxide film or a silicon nitride film (SiN _x ), and the amorphous silicon thin film 140a may be formed using various methods.

Representative methods for depositing an amorphous silicon thin film include a low pressure chemical vapor deposition (LPCVD) method and a plasma enhanced chemical vapor deposition (PECVD) method. In the case of depositing the amorphous silicon thin film by the plasma chemical vapor deposition method, the hydrogen atoms of about 20% are included in the amorphous silicon thin film although there are some differences depending on the temperature of the substrate during deposition. At this time, a dehydrogenation process, which is an annealing process for discharging the hydrogen atoms to the outside, must be followed. This is because when the amorphous silicon thin film containing hydrogen atoms is crystallized by a laser, the hydrogen atoms stick out and a cavity is formed inside the thin film, thereby degrading the quality of the polycrystalline silicon thin film.

Thereafter, a crystallization process of crystallizing the amorphous silicon thin film 140a into the polycrystalline silicon thin film 140b is performed. Examples of the crystallization method include a solid phase crystallization (SPC) method for heat treating an amorphous silicon thin film in a high temperature furnace and an excimer laser annealing (ELA) method using a laser.

The polycrystalline silicon thin film obtained by the solid phase crystallization method has a relatively large grain (grain) of the order of several micrometers, but has a disadvantage in that there are many defects in the grain. The defect is known to adversely affect the performance of the thin film transistor after the grain boundary region.

Excimer laser annealing is a key method for fabricating polycrystalline silicon thin film transistors at low temperatures, and is a method of crystallizing an amorphous silicon thin film by instantaneous irradiation of several tens of nsec to an amorphous silicon thin film with a high energy laser beam. The melting and crystallization of amorphous silicon in a very short time has the advantage that the glass substrate is not damaged at all.

Next, as shown in FIG. 2D, a stopper 170 for use as a mask is deposited on the crystallized polycrystalline silicon thin film 140b using a silicon oxide film or the like. Thereafter, in order to form the stopper 170 pattern, a photoresist 150, which is a photoresist, is applied to the entire surface of the substrate 110.

The photoresist coating process is a process of forming a photoresist on a substrate in a uniform thickness to form a desired pattern, and removes moisture on the surface of the substrate to be applied to the photoresist to improve adhesion between the photoresist and the substrate Applying photoresist to a predetermined thickness on the substrate using a method such as pre-bake, spin coating, and evaporating the solvent remaining in the photoresist applied on the substrate. It consists of a soft-bake step of curing the photoresist.

The photoresist is a novolak based resin-based positive photoresist in which a region exposed to a light source reacts with a developer to dissolve and an acrylic monomer-based monomer in which an exposure region does not react with a developer. There is a negative photoresist.

Next, as shown in FIG. 2E, the coated photoresist 150 is exposed and developed to form a stopper 170 pattern and a photoresist 150 pattern for use as a mask.

The stopper 170 pattern and the photoresist 150 pattern may include a P-type thin film transistor portion and a pixel portion for an n ⁺ doping process defining a source region and a drain region of an N-type thin film transistor of the pixel portion and the driving circuit portion. It is formed in the upper region of the gate electrode of the N-type thin film transistor of the driving circuit portion.

Thereafter, a high concentration of impurity ions are implanted using the stopper 170 pattern and the photoresist 150 pattern as a mask to form a source region 122a and a drain region 123a. At this time, the source region 122a and the drain region 123a of the N-type thin film transistor may have a group 5 element such as phosphorus (P) capable of donating electrons of about 1 × 10 ¹⁵ / cm ³ . It is formed by injecting with a dose.

Next, as shown in FIG. 2F, lightly doped drain (LDD) regions 122L and 123L are formed. The LED areas 122L and 123L are formed by injecting a low concentration of impurities into a predetermined area of the channel layer in order to reduce a current leaking into the channel layer of the thin film transistor in an OFF state.

At this time, in order to inject impurities into the LED areas 122L and 123L, an ashing process is performed to remove a portion of the photoresist 150 corresponding to the widths of the LED areas 122L and 123L. . The etch process refers to a process of oxidizing and blowing away a photoresist by inserting a substrate into an etch chamber and injecting a gas containing oxygen, thereby obtaining a desired photoresist pattern by controlling a gas amount, a substrate temperature, and a time.

Subsequently, a low concentration of impurities are formed to form the LED areas 122L and 123L using the etched photoresist 150a pattern as a mask. Since other impurity regions are already heavily doped, they are not affected by the low concentration impurity doping process using n-type impurities. The LED areas 122L and 123L are formed by ion implantation with a low dose of 3 × 10 ¹³ / cm ³ or less, and serve to reduce leakage current.

Thereafter, an etch and strip process is performed to remove the photoresist patterns 150 and 150a.

Next, as shown in FIG. 2G, to form the P-type thin film transistor of the driving circuit portion, a photoresist 150 pattern covering the N-type thin film transistor region of the circuit portion and the driving circuit portion is formed.

To form a source / drain region 122a and 123a of a P-type thin film transistor, a group III element such as boron (B) that can donate holes is dosed at about 1 × 10 ¹⁵ / cm ³ . Inject).

Thereafter, the photoresist 150 is removed by etching and stripping.

2H shows a step of forming a source electrode and a drain electrode.

As shown in the figure, a conductive metal is deposited on the entire surface of the substrate 110 and then the source / drain electrodes 122 and 123 patterns are formed using a photolithography process.

The source / drain electrodes 122 and 123 are electrically connected to the source / drain regions 122a and 123a ion-implanted at a high concentration in the channel layer, respectively.

Next, as shown in FIG. 2I, an active pattern is formed using the stopper 170 and the source / drain electrodes 122 and 123 as a mask.

That is, by using the stopper 170 and the source / drain electrodes 122 and 123 as a mask, dry etching is performed on the polycrystalline silicon thin film 140b to form an active pattern. Since the dry etching has anisotropic etching characteristics, an active pattern having fine vertical sides may be formed by the injected etching gas.

At this time, the stopper 170 may be etched to a predetermined thickness.

In particular, the polycrystalline silicon thin film 140b and the silicon oxide film, which is the stopper 170, may be selectively etched by adjusting the etching conditions. The thickness of the stopper is generally about 500 μs, compared to the thickness of the polycrystalline silicon thin film used as the channel layer. Is about 1000 kW and the silicon thin film is etched, and there is no problem.

Lastly, as shown in FIGS. 2J and 2K, a second insulating film 150b, which is a planarization film, is deposited on the entire surface of the substrate 110 with a predetermined thickness and then electrically connected between the drain electrode 123 and the pixel electrode 118. Forming a contact hole 180 for.

The contact hole 180 is formed by removing the second insulating layer 115b to expose a portion of the drain electrode 123.

Thereafter, a transparent conductive material such as indium tin oxide (ITO) is deposited, and then the pixel electrode 118 connected to the drain electrode 123 through the contact hole 180 using a photolithography process. Form a pattern.

At this time, wet etching is mainly used as an etching method of the pixel electrode 118. Oxylic acid etching the pixel electrode 118 affects the channel layer, the source / drain electrodes 122 and 123, and the like. Only the indium-tin-oxide film is effectively etched without giving.

In the present exemplary embodiment, the N-type thin film transistor of the driving circuit portion also includes an LED region like the N-type thin film transistor of the pixel portion. However, the N-type thin film transistor may have a structure having no LED region in order to suppress a decrease in driving current. As a result, it is possible to improve the driving capability of the drive circuit element.

In addition, in the present embodiment, the pixel portion thin film transistor is configured as an N-type, but may be configured as a P-type to simplify the process.

When the stopper is used as a mask as in this embodiment, an additional photolithography process is unnecessary in the process of forming the LED area and the process of forming the active pattern. As a result, an increase in yield resulting from a reduction in defects occurring during the photolithography process and a cost reduction due to an improvement in the manufacturing process can be obtained.

Many details are set forth in the foregoing description but should be construed as illustrative of preferred embodiments rather than to limit the scope of the invention. Therefore, the invention should not be defined by the described embodiments, but should be defined by the claims and their equivalents.

As described above, the manufacturing method of the driving circuit-integrated liquid crystal display device of the present invention uses the photoresist pattern according to the mask process for forming the stopper as a mask during the formation of the LED area, that is, the n ^- doping process, thereby dramatically reducing the manufacturing process. This helps reduce costs and improve yield.

Claims (14)

Providing a substrate; Forming a gate electrode on the substrate; Forming a first insulating film on the substrate; Forming a semiconductor layer on the substrate, the semiconductor layer defining a first region, a second region, and a channel region; Forming a photoresist pattern and a stopper pattern on the channel region; Implanting high concentration impurities into a first region using the photoresist pattern and the stopper pattern as a mask; Removing a portion of the photoresist pattern; Implanting low concentration impurities into a second region using the photoresist pattern from which the portion is removed as a mask; Forming a source / drain electrode on the semiconductor layer; Patterning a semiconductor layer using the stopper pattern and a source / drain electrode as a mask; Forming a second insulating film including a contact hole on the substrate; And And forming a pixel electrode connected to the drain electrode through the contact hole. Providing a first substrate divided into a pixel portion and a driving circuit portion; Forming a gate electrode on the substrate; Forming a first insulating film on the substrate; A first semiconductor layer comprising a first region, a second region, and a channel region is formed in the pixel portion on the substrate, and the second semiconductor layer comprising the first region, the second region, and the channel region, the first region, and the channel region. Forming a third semiconductor layer comprising a driving circuit on the substrate; Implanting impurities into the semiconductor layer using the photoresist pattern and the stopper pattern as a mask; Forming a source / drain electrode on the semiconductor layer; Patterning a semiconductor layer using the stopper pattern and a source / drain electrode as a mask; Forming a second insulating film including a contact hole on the substrate; And And forming a pixel electrode connected to the drain electrode of the first semiconductor layer through the contact hole. The method of claim 1 or 2, wherein the first region is a source / drain region. The method of claim 1 or 2, wherein the second region is defined between the first region and the channel region. The method of claim 1 or 2, wherein the stopper is formed of a silicon oxide film or a silicon nitride film. The method of claim 1 or 2, wherein the stopper is formed of a silicon oxide film or a silicon nitride film. The method of claim 2, further comprising: bonding the first substrate and the second substrate which is the color filter substrate. The method of claim 2, wherein the providing of the first substrate further comprises forming a buffer film on the substrate. The method of claim 2, wherein the impurity is implanted into the semiconductor layer using the photoresist pattern and the stopper pattern as a mask. Forming a first photoresist pattern and a stopper pattern on the semiconductor layer; Implanting a high concentration of n-type impurity into a first region of the first semiconductor layer and the second semiconductor layer using the first photoresist pattern and the stopper pattern as a mask while the third semiconductor layer is blocked; Removing a portion of the first photoresist pattern; Implanting a low concentration n-type impurity into a second region of the first semiconductor layer and the second semiconductor layer using the first photoresist pattern from which the portion is removed; Removing the first photoresist; Forming a second photoresist pattern on the stopper pattern; And Injecting high concentration p-type impurities into the first region of the third semiconductor layer using the second photoresist pattern as a mask while the first semiconductor layer and the second semiconductor layer are blocked. Method of manufacturing a liquid crystal display device. The method of claim 9, wherein the forming of the first photoresist pattern and the stopper pattern comprises: Depositing a stopper on the entire surface of the substrate; Forming a first photoresist pattern on the substrate on which the stopper is formed; And And forming a stopper pattern by using the first photoresist pattern as a mask. 10. The method of claim 9, wherein the removing of the portion of the first photoresist pattern comprises an etching step. The method of claim 9, wherein the blocking of the first semiconductor layer, the second semiconductor layer, or the third semiconductor layer uses a photoresist pattern. The method of claim 9, wherein the first photoresist pattern is formed on a predetermined region including a channel region of the first semiconductor layer and the second semiconductor layer and a third semiconductor layer. The method of claim 9, wherein the second photoresist pattern is formed on a channel region of the third semiconductor layer and a predetermined region including the first semiconductor layer and the second semiconductor layer.