KR101190072B1 - Fabricating method of liquid crystal display device - Google Patents

Abstract

 Method of manufacturing a liquid crystal display device according to the present invention comprises the steps of forming an active layer pattern on a substrate; Forming a gate insulating layer on the entire surface of the substrate; Forming a gate electrode and a storage electrode on the gate insulating layer; Doping an N-type impurity into an N-type thin film transistor region of the active layer pattern; Forming an interlayer insulating layer on the entire surface including the gate electrode and the storage electrode; Forming a P-type impurity and forming a pixel electrode on the interlayer insulating layer by using one photomask; And forming a source / drain contact hole in the gate insulating layer and the interlayer insulating layer, and forming a source / drain electrode.

LCD, first photoresist, second photoresist, pixel electrode, partial ashing

Description

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

1A to 1I are cross-sectional views illustrating a method of manufacturing a liquid crystal display device according to the prior art.

2A to 2K are cross-sectional views illustrating a method of manufacturing a liquid crystal display device according to the present invention.

DESCRIPTION OF REFERENCE NUMERALS

202a and 202b: active layer pattern

204a and 204b gate electrodes

205: storage electrode

206, 208, 210: photoresist

212 pixel electrodes

213: contact hole

214: source / drain electrodes

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 device in which the number of photomasks used in the manufacturing process of the liquid crystal display device is reduced.

The liquid crystal display device has recently increased its weight among flat panel displays because of its high contrast ratio, suitable for gradation display and moving picture display, and low power consumption.

The liquid crystal display device includes a liquid crystal panel, a driver serving to supply various signals to the liquid crystal panel, and a backlight device provided on the rear surface of the liquid crystal panel.

The liquid crystal panel includes a thin film transistor array substrate having a switching element for controlling liquid crystal according to a signal supplied from a driver, a color filter substrate having a color filter layer for implementing colors of red, green, and blue, and the two It consists of a liquid crystal layer enclosed between board | substrates.

The driving circuit unit supplies a gate drive for driving the gate wiring, a data drive for driving the data wiring, a timing controller for controlling the gate drive and the data drive, and various driving voltages used in the liquid crystal display device. The power supply unit is provided. The data drive and gate drive are integrated into a plurality of integrated circuits (ICs).

As described above, the integrated data drive IC and the gate drive IC each have a tape automated bonding (TAB) in which an IC is mounted on a tape carrier package (TCP) and connected to a liquid crystal panel according to a method of packaging the liquid crystal display device. And a chip on glass (COG) method in which a drive IC is directly mounted on a thin film transistor array substrate.

Recently, however, the method of forming the drive IC directly on the substrate like the thin film transistor in the display area has been actively studied.

When the drive IC is directly implemented on the thin film transistor array substrate as described above, the thin film transistor array substrate may be divided into a display area and a non-display area.

In the display area of the thin film transistor array substrate, a gate line and a data line for transmitting various signals to each pixel defined by crossing perpendicularly to each other, and a signal are selectively applied to the pixel electrode so that each pixel is connected. A driving pixel thin film transistor and a storage capacitor required to maintain the state of charge until the unit pixel region is addressed by the next addressing signal are formed.

The non-display area includes a thin film transistor for a driving circuit for selectively applying a signal to the gate wiring and a data wiring, and a pad electrode for electrically connecting the thin film transistor for the driving circuit to an external driving circuit.

In such a structure, a pixel driving thin film transistor is an N-type thin film transistor capable of high speed operation, and a thin film transistor for driving circuit is a CMOS (Complementary Metal-Oxide Semiconductor) thin film transistor having a P-type thin film transistor having excellent power consumption.

Meanwhile, in the liquid crystal display, various patterns such as driving elements or wirings are formed on a substrate for displaying an image. The most common technique used to form such a pattern is photolithography.

The photolithography technique forms a photoresist, which is a photosensitive material, on a substrate on which a pattern is to be formed, exposes and develops a photoresist using a patterned photomask, and patterns the photoresist as a mask. By etching the material layer to be etched and then removing the photoresist.

Therefore, in recent years, research on "low mask technology" for increasing productivity and increasing yield of liquid crystal display devices by reducing the number of photolithography processes to a minimum has been actively conducted.

Hereinafter, a manufacturing method according to the related art of a liquid crystal display device in which a drive IC is directly formed on a substrate will be described with reference to the drawings.

1A to 1I are cross-sectional views illustrating a method of manufacturing a conventional liquid crystal display device having a CMOS thin film transistor. Hereinafter, for convenience of description, the liquid crystal display device is divided into a pixel area part and a driving circuit part.

In the first step, as shown in FIG. 1A, active layer patterns 102: 102a, 102b and 102c made of polysilicon are formed on the substrate 101.

In this case, the polysilicon may be amorphous silicon (Amorphous Silicon) deposited on the substrate, and then the amorphous silicon is crystallized into polycrystalline silicon using a laser or the like.

The active layer pattern 102 is patterned into an island shape, wherein the first active layer pattern of the pixel portion and the third active layer pattern 102a and 102c of the driving circuit portion are N-type thin film transistors and P-types, respectively, through post-processing. The thin film transistor becomes a component, and the second active layer pattern 102c of the pixel portion becomes a component of the storage capacitor through a later process.

Although not shown in the drawing, the active layer patterns 102: 102a, 102b, and 102c may be formed on a substrate after forming a buffer layer (not shown) such as silicon oxide (SiO 2) on the substrate 101. This is to prevent impurities such as sodium (Na) present in the insulating substrate 101 from penetrating upwards in a later process.

In the next step, as shown in FIG. 1B, after the photoresist 103 is coated on the entire surface of the substrate 101 including the active layer patterns 102: 102a, 102b, and 102c, a photolithography technique is performed. When the dopant is doped on the entire surface of the substrate while the second active layer pattern 102b is exposed, the dopant is doped into the second active layer pattern 102b of the storage area. This is to increase the conductivity of the second active layer pattern 102b.

As a next step, as shown in FIG. 1C, the gate insulating layer 104 is formed on the entire surface of the insulating substrate 101.

In addition, a metal layer is formed on the gate insulating layer 104, and a first gate electrode 109 and a storage electrode 110 are respectively formed in the pixel portion using a photolithography technique, and a second gate electrode ( 111) and then implant a low concentration of N-type impurities.

In this case, the first gate electrode 109 and the second gate electrode 111 are positioned on the first active layer pattern 102a and the third active layer pattern 103c, respectively, and the storage electrode 110 is the second active layer pattern 102b. ) So that it overlaps.

When the first gate electrode 109, the second gate electrode 111, and the storage electrode 110 are ion-implanted with low concentration N-type impurities into the first and third active layer patterns 102a and 102c, A lightly doped drain (LDD) doping layer 108 is formed on both sides of the first gate electrode 109 and the second gate electrode 111. At this time, regions in which the N-type impurity is not doped are the first channel region 105 and the second channel region 107.

In the LDD doping process, the reason for low concentration of a certain portion of the source and drain regions is to reduce the electric field applied to the junction due to the resistance in the region to reduce the off current and minimize the on current.

In the next step, as shown in FIG. 1D, the photoresist 113 is coated and patterned on the entire surface of the substrate 101 to expose the first active layer pattern 102a of the pixel portion, and then high concentration N-type impurities are removed. Inject.

That is, a portion of the storage region of the driving circuit unit and the pixel unit, the first gate electrode 109 of the pixel unit, and a portion of the first active layer pattern 102a on the side of the pixel block are blocked by the photoresist, and only the first active layer pattern 102a is blocked. Only part of). In this state, the first source and drain regions 112a and 112b are formed in the first active layer pattern 102a of the pixel portion by doping a high concentration of N-type impurities using phosphorus (P) or the like on the entire surface of the substrate 101. Afterwards, the first source and drain regions 112a and 112b are activated.

In the next step, as shown in FIG. 1E, after the photoresist 113 and 114 are removed, the photoresist 115 is applied to the entire surface of the substrate, and then the third active layer pattern 101c is formed using a photo mask. ) Is exposed and a high concentration of P-type impurities is injected.

At this time, since the second gate electrode 111 is blocking the central region (ie, the channel layer) of the third active layer pattern 101c, a high concentration P type using boron (B) or the like on the entire surface of the insulating substrate 101 is used. When the impurities are doped, the second source region and the drain region are formed in the active layer patterns on both sides of the third gate electrode 111 of the driving circuit unit, respectively.

In the next step, as shown in FIG. 1F, after the photoresist layer 115 is removed, the first interlayer insulating layer 118 is formed on the entire surface of the substrate including the first gate electrode 109. By using an etching technique, the gate insulating layer 104 and the first interlayer insulating layer 118 are removed to expose predetermined portions of the first, second source and drain regions 112a, 112b, 116a, and 116b. The first contact hole 117 is formed.

As a next step, as shown in FIG. 1G, a metal is deposited on the first interlayer insulating layer 118 and first and second sources are formed through the first contact hole 117 using a photolithography technique. And first and second source and drain electrodes 112c, 112d, 116c, and 116d connected to the drain regions 112a, 112b, 116a, and 116b to form an N type thin film transistor and a P type thin film transistor. Complete the transistor.

Accordingly, the pixel portion includes an N-type thin film transistor including a first gate electrode 109, a first source electrode, first drain electrodes 112c and 112d, and a first channel region 105, and a second semiconductor layer 102b. And a storage capacitor formed of a gate insulating film 104 and a storage electrode 110 and formed in each pixel, and the second gate electrode 111, the second source electrode, and the drain electrode 116c and 116d are formed in a driving circuit unit. ) And a second channel region 107 are formed.

In the next step, as shown in FIG. 1H, a second interlayer insulating layer 121 is formed on the entire surface of the substrate, and a photolithography technique is performed. The second interlayer insulating layer 121 and the first interlayer insulating layer 118 are etched to expose the first drain electrode 112d and the storage electrode 110 by using the second and third contact holes 119 and 120. ).

In a final step, as shown in FIG. 1I, the third contact hole 120 is electrically connected to the first drain electrode 112d of the N-type thin film transistor through the second contact hole 119. After stacking the transparent conductive layer to be electrically connected to the storage electrode 110 through the), to form a pixel electrode 122 using a photolithography technique.

The thin film transistor array substrate which is one of the components of the liquid crystal display device is completed by the above-described process. The thin film transistor array substrate is bonded to a color filter substrate on which a black matrix, a color filter pattern, a common electrode, and the like are formed, and a liquid crystal panel is filled by filling liquid crystal therebetween.

As described above, in the conventional method of manufacturing a liquid crystal display device in which a CMOS thin film transistor is formed on a substrate, active layer pattern formation, storage doping, N-type impurity doping, P-type impurity doping, first contact hole formation, and source / drain electrode formation In the step of forming the second and third contact holes and forming the pixel electrode, one photolithography technique is used, and a total of eight photolithography techniques are used.

Therefore, the manufacturing process of the liquid crystal display device according to the prior art has a problem that the process is complicated and the cost is increased, and researches for reducing the number of photolithography techniques used in the process are actively conducted.

The present invention is to solve the above problems, the liquid crystal display device manufacturing method of the present invention is a P-type impurity doping process and the pixel electrode forming process by using a single photomask to be used in the manufacturing process of the liquid crystal display device The aim is to reduce the total number of photomasks to six.

Other objects and features of the present invention will be described in the following description of the invention and claims.

Method of manufacturing a liquid crystal display device of the present invention for achieving the above object comprises the steps of forming an active layer pattern on a substrate; Forming a gate insulating layer on the entire surface of the substrate; Forming a gate electrode and a storage electrode on the gate insulating layer; Doping an N-type impurity into an N-type thin film transistor region of the active layer pattern; Forming an interlayer insulating layer on the entire surface including the gate electrode and the storage electrode; Forming a P-type impurity and forming a pixel electrode on the interlayer insulating layer by using one photomask; And forming a source / drain contact hole and forming a source / drain electrode in the gate insulating layer and the interlayer insulating layer.

In the manufacturing method of the liquid crystal display of the present invention, a total of six photomasks are used in the steps of active layer pattern formation, gate electrode formation, N-type impurity doping, P-type impurity doping, pixel electrode formation, and source / drain electrode formation. 2A to 2K will be described in detail the manufacturing process of the liquid crystal display device of the present invention.

2A to 2K are cross-sectional views illustrating a process for manufacturing a liquid crystal display device of the present invention.

In the first step, as shown in FIG. 2A, active layer patterns 202a and 202b made of polycrystalline silicon are formed on the substrate 201 made of a transparent insulating material such as glass by using photolithography.

In this case, although not shown in the drawing, a buffer layer such as silicon oxide (SiO 2) may be formed on the insulating substrate 201, and active layer patterns 202a and 202b may be formed thereon. The buffer layer serves to block impurities such as sodium (Na) present in the insulating substrate 201 such as a glass substrate from penetrating into the upper layer during the process.

The active layer patterns 202a and 202b are made of polysilicon, and the polysilicon may be formed using various crystallization methods after laminating an amorphous silicon layer on the substrate 201.

In the process, the amorphous silicon layer is formed by Low Pressure Chemical Vapor Deposition (LPCVD) or Plasma Enhanced Chemical Vapor Deposition (PECVD), and then the amorphous silicon layer is solid-phase crystallized. It is made by crystallization by the Solid Phase Crystallization (SPC) method or the Eximer Laser Annealing (ELA) method.

As a next step, as shown in FIG. 2B, the gate insulating layer 203 is formed on the substrate including the active layer patterns 202a and 202b, and the gate electrodes 204a and 204b and the storage electrode (b) are formed thereon. 205). The process forms a gate insulating layer 203 made of silicon oxide (SiOx) or silicon nitride (SiNx), on which copper (Cu), aluminum (Al), aluminum alloy (AlNd), molybdenum (Mo), and chromium are formed. After depositing a metal layer such as (Cr) is made using a photolithography technique.

In this case, the gate electrodes 204a and 204b and the storage electrode 205 of the N-type thin film transistor and the P-type thin film transistor are present on the same stacked structure and may be simultaneously formed using one photomask.

In the next step, as shown in FIG. 2C, the photoresist 206 is coated on the entire surface of the substrate including the gate electrodes 204a and 204b and the storage electrode 205, and then, using a photolithography technique. After exposing only the N-type thin film transistor region, the N-type impurity is doped into the exposed N-type thin film transistor region. In this case, since the P-type thin film transistor region and the storage region are blocked by the photoresist 206, it is possible to prevent the doping of impurities into the region.

At this time, the photoresist used in the above process has different development characteristics according to its type. When using a positive photoresist, a portion exposed to light is removed after development and an unexposed portion remains as it is. The resist forms a predetermined pattern, and when a negative photoresist is used, a predetermined pattern is formed while exhibiting developing characteristics opposite to the positive photoresist in the developing step after exposure. Such positive photoresist or negative photoresist may be appropriately selected as necessary, and according to the selection, the pattern of the photomask will be changed to the opposite tone.

Subsequently, the P-type impurity doping and the pixel electrode are formed. Conventionally, separate masks are required to form the P-type impurity doping and the pixel electrode, but in the present invention, one photomask is used to form the P-type impurity doping and the pixel electrode. The P-type impurity doping and the pixel electrode forming process are shown in FIGS. 2D to 2I.

As shown in FIG. 2D, an interlayer insulating layer 207 is formed on the entire surface of the substrate 201, a photoresist is stacked thereon, and a portion of the P-type thin film transistor region and the image display region are formed by using photolithography. A photoresist pattern 208 is formed which exposes the N-type thin film transistor and the image display area in which the storage area is not formed. Subsequently, a high concentration of P-type impurity ions are doped with boron (B) or the like on the entire substrate 201 to form source and drain regions in the active layer pattern 202b of the P-type thin film transistor region.

In the next step, as shown in FIG. 2E, the transparent conductive layer is stacked to form an image display region and a P-type thin film transistor region on the photoresist of the N-type thin film transistor region and the storage region and on the interlayer insulating layer 207. A conductive layer is formed in the. In this case, since the conductive layer 209 must be transparent to transmit the light generated from the backlight, a transparent metal oxide such as indium tin oxide or indium zinc oxide is used.

Subsequently, as shown in FIG. 2F, the photoresist 210 is again applied on the conductive layer 209 (hereinafter, the photoresist used in the P-type impurity doping process may be replaced by the first photoresist, The photoresist applied on the conductive layer to form the pixel electrode is called a secondary photoresist).

In this case, the second photoresist 210 is applied to the N-type thin film transistor region, the storage electrode region, and the P-type thin film transistor region with the same thickness, and in the region where the pixel electrode 212 is located, the second photoresist 210 is formed by the step difference of the lower layer. It is applied thicker than the areas.

After application of the second photoresist 210, the photoresist 210 is partially ashed. By the partial ashing as described above, the second photoresist applied to the N-type thin film transistor region, the storage electrode region, and the P-type thin film transistor region is completely removed, while the first of the relatively thick applied pixel electrode region is removed. The secondary photoresist remains. As a result, the photoresist 211 remains partially only in the pixel electrode region as shown in FIG. 2G after the partial ashing process is performed. That is, only the pixel electrode region is blocked by the photoresist 211.

Therefore, as shown in FIG. 2H, only the conductive layer 209 formed on the first photoresist 208 and on the sidewalls of the first photoresist 208 is removed and the conductive layer blocked by the photoresist 211 is removed. It will remain the same. In this case, a wet etching process may be applied to the etching process. Dry etching may also be applied.

Subsequently, as shown in FIG. 2I, when the first photoresist 208 and the second photoresist 211 are removed, the pixel electrode 212 is formed on the interlayer insulating layer 207. In this case, an ashing process may be applied to the removal of the second photoresist 211 and a strip process may be applied.

Thereafter, as shown in FIG. 2J, contact holes 213 are formed in the gate insulating layer 203 and the interlayer insulating layer 207 by exposing the source and drain regions using photolithography.

In the last step, as shown in Fig. 2K, source and drain electrodes 214 are formed. The process is performed by a photolithography technique after laminating the conductive layer and the photoresist over the entire substrate 201, and as a result, the source of the active layer patterns 202a and 202b through the contact hole 213 and A source and drain electrode 214 is formed to be connected to the drain region, and the drain electrode is connected to the pixel electrode 212.

By the above-described process, the thin film transistor array substrate of the liquid crystal panel, which is one of the components of the liquid crystal display device of the present invention, is completed. The thin film transistor array substrate is bonded to a color filter substrate on which a black matrix, a color filter pattern, a common electrode, and the like are formed, and a liquid crystal panel constituting a liquid crystal display device by filling liquid crystal therebetween is completed.

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 construed as limited to the embodiments described, but should be determined by equivalents to the appended claims and the claims.

As described above, in the method of manufacturing the liquid crystal display device according to the present invention, since the P-type impurity doping process and the pixel electrode forming process are performed using one photomask, active layer pattern formation, gate electrode formation, N-type impurity doping, and P It is possible to fabricate a thin film transistor array substrate using a total of six photomasks in the steps of type impurity doping, pixel electrode formation, and source / drain electrode formation. Therefore, the manufacturing cost of the liquid crystal display device is reduced compared to the prior art, it is also advantageous to improve the production yield.

Claims (10)

Forming an active layer pattern on the substrate; Forming a gate insulating layer on the entire surface of the substrate; Forming a gate electrode and a storage electrode on the gate insulating layer; Doping an N-type impurity into an N-type thin film transistor region of the active layer pattern; Forming an interlayer insulating layer on the entire surface including the gate electrode and the storage electrode; Forming a first photoresist pattern on the interlayer insulating layer to expose a region where a pixel electrode is to be formed and a driving circuit region; Doping a P-type impurity into a driving circuit region using the first photoresist pattern as a mask; Forming a conductive layer on the substrate including the first photoresist pattern; Applying a second photoresist on the conductive layer; Partially ashing the second photoresist so that the second photoresist remains only in the region where the pixel electrode is to be formed; Forming a pixel electrode by etching the conductive layer using a second photoresist remaining in a region where the pixel electrode is to be formed as a mask; Removing the primary and secondary photoresist; And And forming a source / drain contact hole in the gate insulating layer and the interlayer insulating layer, and forming a source / drain electrode. The method of claim 1, And the gate electrode and the storage electrode are formed at the same time. The method of claim 1, And the pixel electrode is made of a transparent metal oxide. The method of claim 3, The transparent metal oxide is a method of manufacturing a liquid crystal display device, characterized in that consisting of indium tin oxide or indium zinc oxide (Indium Zinc Oxide). delete The method of claim 1, The conductive layer is a method of manufacturing a liquid crystal display device, characterized in that the etching by a dry etching process. The method of claim 1, The conductive layer is a method of manufacturing a liquid crystal display device, characterized in that the etching by the wet etching process. The method of claim 1, A method of completely removing the first and second photoresist is carried out by an ashing process. The method of claim 1, A method of completely removing the first and second photoresist is performed by a strip process. The method according to any one of claims 1 to 4, 6 to 9, The liquid crystal display device of claim 1, wherein the color filter substrate is formed by bonding the thin film transistor array substrate.

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