KR19980026562A - LCD and its manufacturing method - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device and a method of manufacturing the same, comprising: a transparent insulating substrate having a switching region and a reflecting region, a gate electrode formed in the switching region on the substrate, and a gate electrode in the switching region and the reflecting region on the substrate. A gate insulating layer formed to cover, amorphous silicon without doping impurities in the switching region on the gate insulating layer, and an island-like active layer overlapping the gate electrode; An ohmic contact layer formed of amorphous silicon doped with a high concentration of impurities, a source and drain electrode formed to contact the gate insulating layer of the switching region on the ohmic contact layer, and a predetermined portion of the drain region exposed to the switching region. The formed protective film layer, the light shielding layer formed on the protective film layer, and the crab A plurality of scattering protrusions formed to have a truncated conical shape by stacking a material forming the passivation layer and the light shielding layer on the insulating layer, and a metal having good battery conductivity and light reflecting property are formed in a reflective region including the scattering protrusions. And a pixel electrode in electrical contact with the source or drain electrode. Therefore, since the active layer and the light shielding layer of the thin film transistor are not in contact with each other, the characteristics and reliability of the thin film transistor are improved, and the protective film layer is patterned using the light shielding layer as a mask after exposure and development of the light shielding layer, thereby simplifying the process. .

Description

LCD and its manufacturing method

1 is a cross-sectional view of a liquid crystal display device according to the related art.

2 is a plan view of a liquid crystal display according to the present invention.

3 is a cross-sectional view taken along line I-I of FIG. 2

4 (a) to (e) are manufacturing process diagrams of the liquid crystal display device according to the present invention.

Explanation of symbols on the main parts of the drawings

31: gate bus line 33: data bus line

41 substrate 43 gate electrode

45 gate insulating layer 47 active layer

49: ohmic contact layer 51: source electrode

52 drain electrode 53 protective film layer

55: light shielding layer 57: scattering projection

59 pixel electrode 61 alignment layer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device and a method for manufacturing the same, and more particularly, to a liquid crystal display device and a method for manufacturing the light shielding layer on a thin film transistor array to improve the aperture ratio.

In the LCD, unit pixels including a thin film transistor as a switching element and a pixel electrode connected thereto are vertically and horizontally arranged in an array state on a lower substrate. The unit pixels arranged in an array state have at least one gate bus line formed thereon to transmit signals by connecting gate electrodes of the thin film transistors arranged along the longitudinal direction (or the transverse direction), and transverse direction (or the longitudinal direction). At least one data bus line is formed to intersect with the gate bus line so that the source electrodes of the thin film transistors arranged along the s) are connected to each other to transmit signals. The substrate thus formed is commonly referred to as a thin film transistor array substrate or a lower substrate. In addition, light blocking layers formed at positions corresponding to regions other than the pixel electrodes, corresponding electrodes to which a common voltage is applied to the pixel electrodes, and color filters are formed on other substrates. The other substrate thus formed is usually referred to as a counter electrode substrate or an upper substrate. The upper substrate and the lower substrate are bonded to each other and the liquid crystal is injected into the space therebetween. Before the bonding process, polyimide or the like is applied to the upper substrate and the lower substrate and rubbed to form an alignment layer.

In the liquid crystal display of the above structure, since the light blocking layer is formed on the upper substrate, the thin film transistor and the light blocking layer, which may occur when the upper substrate and the lower substrate are bonded to each other, are not aligned with each other, and an alignment error is generated. Since the margin must be calculated and formed, the size of the plane becomes large, and thus the aperture ratio of the liquid crystal display is reduced.

Therefore, by forming a light blocking layer on the thin film transistor array to prevent an alignment error between the thin film transistor and the light blocking layer when the upper substrate and the lower substrate are bonded to each other, the plane size of the light blocking layer can be reduced to improve the aperture ratio. Has been developed.

1 is a cross-sectional view of a liquid crystal display device according to the prior art.

The liquid crystal display according to the related art is divided into a switching region s in which a thin film transistor is formed, a scattering protrusion 25, and a pixel electrode 28, in which a scattering light is reflected to reflect light.

The thin film transistor includes a gate electrode 13, a gate insulating layer 15, an active layer 17, an ohmic contact layer 19, a source and a drain electrode 23 on the switching region s on the transparent insulating substrate 11. (24), the light shielding layer (23), and the protective film layer (27).

The gate electrode 13 is formed in a predetermined portion of the switching region s on the substrate 11, and the gate insulating layer 15 is formed in the switching region s and the reflective region r to cover the gate electrode 13. Is formed. The active layer 17 is formed to correspond to the gate electrode 13 formed in the switching region s on the gate insulating layer 15, and the ohmic contact layer 19 is formed on both sides of the active layer 17. Source and drain electrodes 23 and 24 are formed on the ohmic contact layer 19 to be in contact with the gate insulating layer 15. A light blocking layer 23 is formed on the exposed portion of the active layer 17 of the switching region s and the source and drain electrodes 21 and 22 to prevent light from being transmitted. The light blocking layer 23 is formed to expose a predetermined portion of the drain electrode 22.

The scattering protrusions 25 form a truncated cone shape having a predetermined inclination angle on the gate insulating layer 15 of the reflection region r, and a plurality of scattering protrusions 25 are formed. The scattering protrusions 25 are formed of the same opaque insulating resin as the light shielding layer 23 and are formed by the same exposure and development process.

The protective film layer 27 is formed by applying a polymer resin or the like to expose the drain electrode 22 on all surfaces of the switching region s and the reflective region r. The pixel electrode 28 is formed to be electrically connected to the drain electrode 22 on the passivation layer 27 of the reflective region r. The pixel electrode 28 reflects, while scattering, ambient light incident through the color filter of the upper substrate so that the surface of the pixel electrode 28 is not flattened by the scattering protrusions 25, thereby improving the viewing angle. Then, the alignment layer 29 is formed by applying and rubbing polyimide or the like on the protective film layer 27 and the pixel electrode 28.

In the above-described conventional liquid crystal display device, since the light blocking layer is formed on the thin film transistor, the thin film transistor and the light blocking layer are matched with each other when the corresponding electrode to which the common voltage is applied and the upper substrate on which the color filter is formed prevent the alignment error from occurring. Therefore, the aperture ratio can be improved while reducing the plane size of the light shielding layer.

However, the liquid crystal display of the above-described structure has a problem in that the characteristics of the thin film transistor and the reliability of the thin film transistor are deteriorated because the threshold voltage is changed by the light blocking layer being in contact with the active layer serving as the channel. In addition, since the protective layer is patterned by another mask as a mask for exposing and developing the light shielding layer and the scattering protrusion, there is a problem in that the process is complicated.

Accordingly, an object of the present invention is to provide a liquid crystal display device which can improve characteristics and reliability of a thin film transistor by preventing an active layer and a light blocking layer from contacting each other.

Another object of the present invention is to provide a method of manufacturing a liquid crystal display device having a simple process since the protective film layer is patterned by using the light shielding layer as a mask after exposure and development.

According to an exemplary embodiment of the present invention, a liquid crystal display device includes a transparent insulating substrate having a switching area and a reflection area, a gate electrode formed in the switching area on the substrate, and a gate electrode in the switch area and the reflection area on the substrate. A gate insulating layer formed to cover, amorphous silicon without doping impurities in the switching region on the gate insulating layer, and an island-like active layer overlapping the gate electrode; An ohmic contact layer formed of amorphous silicon doped with a high concentration of impurities, a source and drain electrode formed to contact the gate insulating layer of the switching region on the ohmic contact layer, and a predetermined portion of the drain region exposed to the switching region. The formed protective film layer, the light shielding layer formed on the protective film layer, and the crab A plurality of scattering protrusions formed to have a truncated conical shape by stacking a material forming the passivation layer and the light shielding layer on the insulating layer, and formed of a metal having good electrical conductivity and light reflecting property in the reflective region including the scattering protrusions. And a pixel electrode in electrical contact with the source or drain electrode.

According to another aspect of the present invention, there is provided a method of manufacturing a liquid crystal display device, the method including forming a gate electrode in the switching region on a transparent insulating substrate having a switching region and a reflective region, and covering the gate electrode on the substrate. Forming a gate insulating layer in the switching region and the reflective region, and amorphous silicon not doped with impurities in the portion corresponding to the gate electrode on the gate insulating layer and amorphous silicon doped with a high concentration of impurities. Forming an active layer and an ohmic contact layer of the active layer; and forming source and drain electrodes on both side portions of the ohmic contact layer and the gate insulating layer, and using the source and drain electrodes as a mask to expose the ohmic contact layer. Removing a portion of the active layer to expose the active layer; Forming a protective film layer and a light shielding layer on the gate insulating layer in the region, and patterning the exposed portion of the source or drain electrode to remain exposed on the switching region with the same mask; And forming a pixel electrode in contact with the source or drain electrode and electrically connected to the reflective region including the scattering protrusion.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

2 is a plan view of a liquid crystal display according to the present invention.

In the liquid crystal display according to the present invention, a switching region S in which a thin film transistor is formed, a scattering protrusion 57, and a pixel electrode 59 are formed to reflect and scatter light and reflect light.

The gate bus line 31 and the data bus line 33 vertically cross each other in the switching region S. A gate electrode 43 extending from the gate bus line 31 and a source electrode 51 extending from the data bus line 33 are formed at the intersection of the gate bus line 31 and the data bus line 33. . A drain electrode 52 corresponding to the source electrode 51 is formed around the gate electrode 43, and an active layer 47 that is not doped with island-like impurities overlapping the gate electrode 43 is formed. .

In addition, a plurality of truncated cone-shaped scattering protrusions 57 are formed in the reflective region R between the gate bus line 31 and the intersection of the data bus line 33, and the pixel electrode 59 is the drain electrode 52. It is formed to be electrically connected with. In addition, the light blocking layer 55 is formed in the switching region S in which the gate bus line 31 including the gate electrode 43 and the data bus line 33 including the source electrode 51 are formed. The light blocking layer 55 is formed to overlap the edge of the pixel electrode 59 of the reflective region R so that the light blocking layer 55 is shielded to the area between the gate bus line 31 and the data bus line 33 and the pixel electrode 59. do.

3 is a cross-sectional view taken along line II of FIG. 2.

In the thin film transistor according to the present invention, a gate electrode 43 is formed in the switching region S on the substrate 41 made of a transparent and insulating material, and is formed on the switching region S and the reflective region R. A gate insulating layer 45 covering the gate electrode 43 is formed. The gate electrode 43 may be formed of conductive materials such as aluminum (Al), aluminum alloy, molybdenum (Mo), molybdenum alloy, titanium (Ti), titanium alloy, tantalum (Ta), tantalum alloy, cobalt (Co) or cobalt alloy. The metal is formed to a thickness of about 2000 ~ 3000Å. The gate insulating layer 45 is formed by depositing an insulating material such as silicon oxide (SiO) or silicon nitride (SiN) in a thickness of about 3000 to about 4000 kPa.

In the switching region S on the gate insulating layer 45, an active layer 47 is formed in which amorphous silicon, which is not doped with impurities, overlaps with the gate electrode 43, and is used as a channel having a thickness of about 1500 to 2000 μs. On both sides of the active layer 47, an ohmic contact layer 49 having an impurity doped amorphous silicon having a thickness of about 500 to 1000 Å is formed, and aluminum or on the ohmic contact layer 49 and the gate insulating layer 45 are formed. The source and drain electrodes 51 and 52 in which a metal such as chromium (Cr) is formed to have a thickness of about 2000 to 3000 kPa are formed.

The ohmic contact layer 49 is doped with an N-type impurity such as phosphorus (P) or a P-type impurity such as boron (B) at a high concentration so that the active layer 47 may be source and drain electrodes 51 and 52. Contact with ohmic. In addition, a protective film layer in which an insulating material such as silicon oxide (SiO) or silicon nitride (SiN) is deposited on the exposed portion of the active layer 47 and the source and drain electrodes 51 and 52 to a thickness of about 3000 to 4000 kPa. 53 is formed, and the light shielding layer 55 which the thickness of about 1.5-4.5 micrometers of opaque insulating resin is formed on this protective film layer 53 is formed.

A plurality of scattering protrusions 57 having a conical shape are formed in the reflective region R on the gate insulating layer 45. The scattering protrusions 57 are formed of the same material as the material forming the passivation layer 53 and the light shielding layer 55 of the thin film transistor, and have a height of about 2 to 5 μm and an inclination angle of about 30 to 60 ° and are adjacent to each other. It has a spacing of about 3 to 5㎛ the scattering projections 57. In addition, the thin film transistor includes a pixel electrode 59 having a thickness of about 1500 to 4000 microns of aluminum or an aluminum alloy having good electrical conductivity and light reflecting properties on the entire surface of the reflective region R including the surface of the scattering protrusion 57. In contact with the drain electrode 52 of about 1 to 3㎛ is exhibited to be electrically connected. The pixel electrode 59 reflects, while scattering, ambient light incident through the color filter of the upper substrate (not shown) by the scattering protrusion 57, thereby improving a view angle.

An alignment layer 61 made of polyimide or the like is formed on the light shielding layer 59, the passivation layer 55, and the pixel electrode 59 formed in the switch region S and the reflective region R, respectively. The alignment layer 61 is rubbed after application so that the liquid crystal placed on top is aligned in a desired direction.

In the liquid crystal display having the above-described structure, the light shielding layer 55 is formed on the passivation layer 53 of the thin film transistor to prevent light from being incident into the switching region S so that only the reflective region R is incident.

4 (a) to (e) are manufacturing process diagrams of the liquid crystal display device according to the present invention.

Referring to FIG. 4A, anodes such as aluminum, aluminum alloys, molybdenum, molybdenum alloys, titanium, titanium alloys, tantalum, tantalum alloys, cobalt or cobalt alloys may be used in the switching region S on the transparent insulating substrate 41. The metal to be oxidized is deposited to a thickness of about 2000 to 3000 mm by chemical vapor deposition (CVD) or sputtering, and patterned by a conventional photolithography method to the switching region S. The gate electrode 43 is formed.

Referring to FIG. 4B, a silicon oxide film or a silicon nitride film is deposited in the switching region S and the reflecting region R on the substrate 41 to a thickness of about 3000 to 4000 microseconds by a CVD method. A gate insulating layer 45 covering the gap is formed. In addition, N-type impurities such as amorphous silicon and phosphorus (P), which are not doped with impurities, and amorphous silicon doped with high concentration of P-type impurities such as boron (B) are deposited on the gate insulating layer 45 by the CVD method. The active layer 47 and the ohmic contact layer 49 are sequentially formed. In this case, the active layer 47 is used as a channel, and is formed to a thickness of about 1500 to 2000 micrometers, and the ohmic contact layer 49 is formed to a thickness of about 500 to 1000 micrometers. Then, the active layer 47 and the ohmic contact layer 49 are left in the switching region S, and the gate insulating layer 45 is removed by the photolithography method so as to overlap the gate electrode 43. Expose

Referring to FIG. 4 (c), a conductive metal such as aluminum or chromium (Cr) is deposited on the ohmic contact layer 49 and the insulating film 45 to a thickness of about 2000 to 3000 microns, and then the conductive metal is ohmic. The source and drain electrodes 51 and 52 are formed by patterning the photolithography method so that a predetermined portion of the contact layer 49 and the gate insulating layer 45 of the reflective region R are exposed. The exposed portion of the ohmic contact layer 49 is removed using the source and drain electrodes 51 and 52 as a mask to expose the active layer 47. At this time, in order to prevent the residue of the ohmic contact layer 49 from remaining on the active layer 47, the active layer 47 is also over-etched so that a thickness of about 200 to 300 kPa is removed.

Referring to FIG. 4 (d), the exposed portion of the active layer 47 formed on the entire surface of the above-described structure, that is, the switching region S and the reflective region R, and the source and drain electrodes 51 ( A protective film layer 53 is formed by depositing a silicon oxide film or a silicon nitride film to a thickness of about 3000 to 4000 microns on the gate insulating layer 45 including the 52. The light-shielding layer 55 is formed on the protective film layer 53 by coating an opaque insulating resin with a thickness of about 1.5 to 4.5 μm. Next, the light shielding layer 55 is exposed and developed to cover the thin film transistor in the switching region S and form a plurality of truncated cones in the reflective region R. FIG. At this time, the light shielding layer 55 adjusts the exposure amount to achieve an inclination angle of about 30 to 60 degrees. The protective film layer 53 is plasma-etched using the remaining truncated truncated light shield layer 55 as a mask and SF ₆ + He as an etching gas to expose the gate insulating layer 45. At this time, the protective film layer 53 and the light shielding layer 55 remaining in the reflective region R become scattering protrusions 57. The scattering protrusions 57 have a height of 2 to 5 µm and a height of 30 to 60 °. It is formed to have an inclination angle of about a distance between the adjacent scattering projections 57 and about 3 ~ 5㎛.

Referring to FIG. 4 (e), aluminum or an aluminum alloy having good electrical conductivity and light reflecting properties is deposited on the entire surface of the structure described above with a thickness of about 1500 to 4000 mm by sputtering or the like. Then, the light blocking layer 55 of the switching region S is patterned to be in contact with the drain electrode 52 of the thin film transistor in the reflective region R including the surface of the scattering protrusion 57 by about 1 to 3 μm. The pixel electrode 59 is electrically connected. Next, the alignment layer 61 is formed by coating and rubbing polyimide or the like on the light shielding layer 55 and the pixel electrode 59.

As described above, a liquid crystal display device capable of increasing a viewing angle by scattering and reflecting ambient light incident by a scattering protrusion formed in a truncated cone in a reflective area according to the present invention can increase the viewing angle. And the light shielding layer are sequentially stacked, and then the light shielding layer of the switching region is exposed and developed, and when the protective film layer is patterned using the light shielding layer as a mask, the light shielding layer of the reflective region is exposed and developed, and the protective film layer is patterned to form scattering protrusions. do.

Therefore, in the liquid crystal display according to the present invention, since the active layer and the light blocking layer of the thin film transistor are not in contact with each other, the characteristics and reliability of the thin film transistor are improved, and after exposing and developing the light blocking layer, the light blocking layer is used as a protective film. Patterning the layer has the advantage of simplifying the process.

Claims (13)

A transparent insulating substrate having a switching region and a reflecting region, A gate electrode formed in the switching region on the substrate; A gate insulating layer formed to cover the gate electrode in the switch region and the reflective region on the substrate; An island-like active layer made of amorphous silicon which is not doped with impurities in the switching region on the gate insulating layer and overlaps with the gate electrode; An ohmic contact layer formed of amorphous silicon doped with a high concentration of impurities in both portions except the center portion of the active layer; Source and drain electrodes formed on the ohmic contact layer to be in contact with the gate insulating layer of the switching region; A passivation layer formed to expose a predetermined portion of the drain region in the switching region; A light shielding layer formed on the protective film layer; A plurality of scattering protrusions formed to form a truncated cone by stacking a material forming the light shielding layer with the passivation layer on the gate insulating layer; And a pixel electrode formed of a metal having good electrical conductivity and light reflecting characteristics in the reflective region including the scattering protrusions and being electrically connected to the source or drain electrode. The method of claim 1, The protective layer is a liquid crystal display device wherein the silicon oxide film or silicon nitride film is formed to a thickness of 3000 ~ 4000Å. The method of claim 1, The light blocking layer is a liquid crystal display device wherein the opaque insulating resin is formed to a thickness of 1.5 ~ 4.5㎛. The method of claim 1, The scattering protrusions are formed to have a height of 2 to 5㎛ and an inclination angle of 30 to 60 °. The method of claim 4, wherein The scattering protrusions have a distance of 3 to 5 μm from adjacent scattering protrusions. The method of claim 1, And a pixel electrode formed of aluminum or an aluminum alloy. The method of claim 6, And a pixel electrode having a thickness of 3000 to 4000 kV. Forming a gate electrode in said switching region on a transparent insulating substrate having a switching region and a reflective region; Forming a gate insulating layer in the switching region and the reflective region on the substrate to cover the gate electrode; Forming an island-like active layer and an ohmic contact layer using amorphous silicon that is not doped with impurities and amorphous silicon that is heavily doped with impurities in a portion corresponding to the gate electrode on the gate insulating layer; Forming source and drain electrodes on both sides of the ohmic contact layer and the gate insulating layer, and removing the exposed portions of the ohmic contact layer to expose the active layer by using the source and drain electrodes as masks; After forming a passivation layer and a light shielding layer on the surface of the switching region and the gate insulating layer of the reflective region, patterning so that a predetermined portion of the source or drain electrode remains exposed on the switching region with the same mask and at the same time a reflective region Forming a scattering protrusion in the And forming a pixel electrode in contact with the source or drain electrode and electrically connected to the reflection region including the scattering protrusion. The method of claim 8, A method of manufacturing a liquid crystal display device, wherein the protective film layer is formed to have a silicon nitride film having a thickness of 3000 to 4000 GPa. The method of claim 8, The light shielding layer is formed by applying an opaque insulating resin to a thickness of 1.5 ~ 4.5㎛. The method of claim 8, The scattering protrusions have a height of 2 to 5㎛ and an inclination angle of 30 to 60 °. The method of claim 11, And the scattering protrusions have a distance of 3 to 5 μm from the adjacent scattering protrusions. The method of claim 8, And forming an alignment layer on the light blocking layer and the pixel electrode.