KR100461092B1 - A process for manufacturing reflective tft-lcd with rough diffuser - Google Patents

Abstract

A manufacturing method of a TFT-LCD device having a rough pixel electrode is described. The method consists of the following steps. First, a first metal layer is formed on a substrate. Thereafter, a first etching process of etching the first metal layer is performed to form a gate structure. Next, a first insulating layer is formed on the gate structure and the substrate. Then, a semiconductor layer is formed on the first insulating layer on the gate structure. Thereafter, a second metal layer is formed on the first insulating layer and the semiconductor layer. A second etching process of etching the second metal layer is performed to form a drain / source structure. Passivation layers are sequentially formed on the drain / source structure. Next, a pixel electrode is formed on the passivation layer to electrically connect the source structure, and the pixel electrode has a rough surface due to at least one kind of bump formed on the substrate. The bump is composed of the first bump and the second bump, and the first bump formed of the first metal layer is formed simultaneously in the first etching process, and the second bump formed of the second metal layer is formed simultaneously in the second etching process.

Description

Manufacturing Method of Reflective TFT-LCD With Coarse Diffuser {A PROCESS FOR MANUFACTURING REFLECTIVE TFT-LCD WITH ROUGH DIFFUSER}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a TFT liquid crystal display device, and more particularly, to a method of manufacturing a pixel electrode having a rough diffuser serving as a reflection member of a TFT-LCD device.

With the development of thin film transistor manufacturing technology, liquid crystal display (LCD) is used for PDA, laptop, cell phone, high resolution TV, etc. due to advantages such as small size, portability and low power consumption. It is widely used in electrical appliances. In particular, recent reflective LCD devices usually use the reflection of external incident light, and the pixel electrode made of a metallic material is used to act as a reflecting member. Therefore, the light reflected from the pixel electrode displays an image on the display through the liquid crystal molecules and the color filter. Reflective LCDs, which do not require back light, are being actively developed due to power savings, thin film, and light weight. In addition, since no backlight member is required, the cost can be reduced.

Since the light source of the reflective LCD is external lighting, it is very important to increase the light reflection efficiency. In the prior art, a polarizer is introduced to increase the reflectance to adjust the phase of incident light. However, it is not practical to use additional polarizers in reflective LCDs. Another solution is to produce pixel electrodes with rough surfaces that act as reflection diffusers to take full advantage of external illumination and to increase reflectance and contrast.

1 is a cross-sectional view of a rough reflective TFT-LCD manufactured in the prior art. The relevant process consists of the following steps. First, the gate structure 12 is formed on the glass substrate 10. Thereafter, the insulating layer 14 is formed on the surface of the gate structure 12. A semiconductor layer 16 such as amorphous silicon, a doped silicon layer 18 and a metal layer are successively formed on the gate structure 12. Next, a photolithography process is performed to form the drain structure 20 and the source structure 22. After the TFT-LCD is manufactured, an additional step for forming a plurality of bumps 26 composed of photoresist is performed in the region where the pixel electrode is formed. Next, a passivation layer 30, such as a polymer material, is formed over the layers. Thus, the reflectance increases due to the pixel electrode having a rough and uneven surface.

However, in order to form the bumps 26, first, a photosensitive layer is deposited on the glass substrate 10, and a bump pattern is formed by performing lithography, developing and baking processes. It is necessary to prepare additional reticles to carry out the process. Thus, additional photomasks and associated processes result in longer cycles and reduced throughput. In addition, since the thin film transistors 24, scan lines, data lines and capacitors are formed before the bump 26 forming step, the bump 26 forming step usually damages the glass substrate and the device.

It is a first object of the present invention to provide a method for manufacturing a TFT-LCD device having a pixel electrode having a rough surface serving as a reflection member.

It is a second object of the present invention to provide a method of manually stacking three different types of bumps to roughen and uneven the surface of a pixel electrode to form a pixel electrode having a rough surface.

It is a third object of the present invention to provide a method of forming a bump under a pixel electrode such that the pixel electrode has a curved surface without an additional lithography etching process.

It is a fourth object of the present invention to provide a method of manufacturing a rough reflective TFT-LCD by simultaneously forming a plurality of bumps for causing the reflective member to have a rough surface in the pattern forming step of the thin film transistor.

1 is a cross-sectional view of a transparent substrate for explaining a TFT-LCD having a rough reflective member according to the prior art.

2 is a cross-sectional view of the transparent substrate for explaining the step of forming the first metal layer on the substrate according to the present invention.

3 is a cross-sectional view of a transparent substrate for explaining a step of forming a gate structure and a plurality of first bumps according to the present invention.

4 is a cross-sectional view of a transparent substrate for explaining a step of sequentially forming a first insulating layer, a gate insulating layer, and a semiconductor layer according to the present invention.

5 is a cross-sectional view of a transparent substrate for explaining a semiconductor layer pattern forming step and a second insulating layer deposition step according to the present invention.

6 is a cross-sectional view illustrating a transparent substrate for explaining an etching stopper forming step and a second metal layer deposition step according to the present invention.

7 is a cross-sectional view of the transparent substrate illustrating the step of forming the drain / source structure according to the present invention.

8 is a cross-sectional view of a transparent substrate for explaining a step of forming a pixel electrode on a passivation layer according to the present invention.

9 is a cross-sectional view of a transparent substrate for explaining a gate structure forming step according to the second embodiment of the present invention.

10 is a cross-sectional view of a transparent substrate for explaining an etching stopper and a plurality of second bump forming steps according to the present invention.

11 is a cross-sectional view of a transparent substrate for explaining a step of forming a pixel electrode on a second bump according to the present invention.

12A to 12L are cross-sectional views of transparent substrates showing that a surface of a pixel electrode rises and falls due to a stacked structure by applying three types of bumps according to the present invention.

13 is a cross-sectional view of the transparent substrate illustrating that the angle of the rough surface of the pixel electrode is smoothed and constant using the cover layer according to the present invention.

A method of forming a TFT-LCD having a rough pixel electrode serving as a diffuser member is described below. The method consists of the following steps. First, a first metal layer is formed on a substrate. A first etching process is performed to etch the first metal layer forming the gate structure. Thereafter, a first insulating layer is formed on the gate structure and the substrate. A semiconductor layer is formed on the first insulating layer over the gate structure. Next, a second insulating layer is formed on the semiconductor layer and the first insulating layer. A second etching process is performed to form a second insulating layer that forms an etch stopper on the gate structure. Subsequently, a second metal layer is formed on the gate structure, and a third etching process is performed to etch the second metal layer forming the drain / source structure next to the etch stopper. Next, a passivation layer that is etched to expose a portion of the drain / source structure is formed on the drain / source structure and the first insulating layer. Thereafter, a pixel electrode electrically connected to the drain / source structure is formed on the passivation layer.

It should be noted that the pixel electrode has a rough surface that replicates from at least one type of bump formed on the substrate. The bump consists of a first bump, a second bump, and a third bump, the first bump consisting of a first metal layer and formed simultaneously in a first etching process, and the second bump consisting of a second insulating layer and a second bump. The third bump is formed at the same time in the etching process, the third bump is composed of the second metal layer and is formed at the same time in the third etching process.

Hereinafter, a method of manufacturing a TFT-LCD having a pixel electrode serving as a diffuser will be described. The plurality of bumps are simultaneously formed in a region of the pixel electrode during the formation of various patterns for forming the thin film transistor. Thus, the pixel electrode can replicate the non-uniform surface at the bottom bumps. And, the rough and non-uniform shape of the pixel electrode can be adjusted by arranging and stacking different bumps arbitrarily. It will be described in detail below.

First embodiment

Referring to FIG. 2, in the first embodiment of the present invention, a PVD process such as sputtering is performed to form the first metal layer 52 on the transparent insulating substrate 50. It is preferable that the board | substrate 50 is comprised from glass, quartz, etc. The first metal layer may be selected from aluminum (Al), titanium (Ti), chromium (Cr), tungsten (W), tantalum (Ta), a group of alloys, and a combination thereof. Thereafter, a photoresist material is applied to the first metal layer and a lithography process is performed to form a plurality of photosensitive bumps 54 on the first metal layer 52.

Next, as shown in FIG. 3, the first metal layer is formed to apply the photosensitive bumps 54 for the etching mask to simultaneously form the gate structure 56 and the plurality of first bumps 58 on the substrate 50. The first etching step of etching is performed. It should be noted that the first bumps 58 should be formed in the predetermined area A, which later forms the pixel electrodes. As is known, a capacitor storage electrode and a data line and a scan line (both not shown) are simultaneously formed on the substrate 50 when the first etching process of forming the gate structure is performed. In a preferred embodiment, a reactive ion etching (RIE) process is applied to form the gate structure 56 and the first bumps 58. After the first etching process, the remaining photosensitive bumps 54 are completely removed.

Next, referring to FIG. 4, a first insulating layer 60 is deposited on the gate structure 56, the first bumps 58, and the substrate 50. In general, the first insulating layer 60 may be selected from oxide, nitride or the like. In a preferred embodiment, a silicon oxide layer or nitride layer can be formed by a plasma enhance chemical vapor deposition (PECVD) process. Thereafter, the gate insulating layer 62 and the semiconductor layer 64 are successively deposited on the first insulating layer, and the gate insulating layer 62 is made of nitride or the like. A material such as amorphous silicon can be applied to form the semiconductor layer 64 forming the channel in the latter portion of the TFT device.

Referring to FIG. 5, the semiconductor layer 64 and the gate insulating layer 62 are etched to form a channel pattern on the gate structure 56 and to deposit a surface of the first insulating layer 60. Thereafter, the first insulating layer 66 is formed to apply the semiconductor layer 64 and the first insulating layer 60. Next, as illustrated in FIG. 6, a second etching process is performed to etch the second insulating layer 66 forming the etch stopper 67 on the gate structure 56 and the semiconductor layer 64. Thereafter, the doped silicon layer 68 and the second metal layer 70 are formed on the outer surfaces of the etch stopper 67, the semiconductor layer 64, and the first insulating layer 60.

Referring to FIG. 7, a third etching process may be performed to form a source structure 72 and a drain structure 74 on the semiconductor layer 64 and beside the etching stopper 67, respectively. The silicon layer 68 is etched. An etching stopper 67 is disposed to prevent the semiconductor layer 64 from being damaged in the third etching process. After forming the source structure 72 and the drain structure 74, a passivation layer 76 is formed on the substrate 50, and a portion of the source structure 72 and the drain structure 74 for electrical connection by an etching process. Expose

Referring to FIG. 8, the pixel electrode 78 is formed on the passivation layer 76 electrically connected to the drain structure 74. Since the pixel electrode 78 acts as a reflecting member of the reflective TFT-LCD device, a material of high reflectance such as metal is used to form the pixel electrode. In a preferred embodiment, the pixel electrode is made of aluminum. Note that there are a plurality of first bumps 58 formed in the region of the pixel electrode 78 in the first etching process. Thus, the first insulating layer 60 and the passivation layer 76 formed thereon can replicate the rough and uneven shape of the bump 58. Thus, the pixel electrode also has a curved surface that acts as a rough diffuser.

Second embodiment

Referring to FIG. 9, similar to the above description, after the first metal layer is formed on the transparent insulating substrate 50, the gate structure 56 is formed by the first etching process. It should be noted that the first bump (see FIG. 3) may not be formed in a region in which the pixel electrode to be deposited later is formed in the first etching process of forming the first gate structure 56. Thereafter, the first insulating layer 60 is deposited on the gate structure 56 and the substrate 50. Similarly, the first insulating layer 60 may be composed of nitride or oxynitride.

Referring to FIG. 10, the gate insulating layer 62 and the semiconductor layer 64 are successively deposited on the first insulating layer 60. An etching process is performed to form a pattern of the semiconductor layer 64 on the gate structure 56. Thereafter, a second insulating layer is formed on the semiconductor layer 64 and the first insulating layer 60. Next, a second etching process is performed to etch a second insulating layer forming the etch stopper 67 on the gate structure 56, and simultaneously to form a second bump on the first insulating layer 60 in the region of the pixel electrode. do.

Referring to FIG. 11, as described in the first embodiment, the doped silicon layer 68 and the second metal layer 70 are formed on the substrate 50. Then, a third etching process is performed to form a source structure 72 and a drain structure 74 next to the etch stopper 67. The passivation layer 76 is formed continuously on the thin film transistor and the second bump 69. Thereafter, an etching process is performed to expose a portion of the source structure 72 and the drain structure 74. Next, the pixel electrode 78 is formed on the passivation layer 76 electrically connected to the drain structure 74. Note that the second bump 69 is formed in the pixel electrode region at the same time as the etching stopper 67 is formed in the second etching process. Thus, the passivation layer 76 formed thereon can replicate the rough and non-uniform shape from the second bumps 69. Thus, later deposited pixel electrode 78 also has a curved surface that acts as a rough diffuser.

That is, in the first embodiment, the first bumps 58 are formed while etching the first metal layer. Thus, the pixel electrode serving as the reflective member has a rough surface due to the shape to be replicated in the underlying layer. In a relatively second embodiment, the second bumps 69 are formed during the etching of the second insulating layer 66 so that the pixel electrode 78 has a replicated rough surface.

The rough reflective surface can be reliably formed by an etching process to form the second metal layer. For example, after depositing the second metal layer 70 on the first insulating layer 60, a third etching process is performed to form the drain structure 72 and the source structure 74 thereon, and simultaneously The third bump 71 is formed. Thereafter, the deposited passivation layer 76 and the pixel electrode 78 can also replicate the rough outer shape from the third bump 71.

Apparently, the thicknesses of the first bump, the second bump, and the third bump are limited by the first metal layer 52, the second insulating layer 66, and the second metal layer 70, respectively. That is, in an actual process, the thickness of the bumps is limited by the gate structure and the etch stopper and drain structure, respectively. However, the surface shape of the pixel electrode can still be adjusted by adjusting the width of the bumps. For example, by narrowing the distance between two adjacent bumps and reducing the width of all the bumps, a pixel electrode having a high-density rough surface can be obtained.

Also, in this embodiment, only one type of bump can be used to form the rough diffuser surface, such as the first bump, the second bump, or the third bump. In practical applications, however, all types of bumps may be used or arbitrarily stacked to form the desired rough reflective surface. That is, three different types of bumps may be manually stacked to form various stacked structures for making pixel electrodes having various and rough surface shapes. By stacking three types of bumps together, the height of the stacked structure can be further increased.

With reference to Figs. 12A to 12I, some laminate structures will be described. In FIG. 12A, the first metal layer 52 is etched to form a first bump 58 on the substrate 50. After depositing the first insulating layer 60, a second etching process is performed to form second bumps respectively positioned between the pattern of the second insulating layers 66 and two adjacent first bumps 58. . At this time, the first bump 58 and the second bump 69 may be arbitrarily applied to obtain a rough and uneven surface of the pixel electrode.

Similarly, the second bump may be formed on the first bump 58 vertical to make the pixel electrode more rough as shown in FIG. 12B. In FIG. 12C, a more dense and dense second bump 69 is formed between the first bump 58 vertically above and two adjacent first bumps. In FIG. 12D, the first, second and third bumps are sequentially stacked, where the second bumps are formed above the first bump vertical and each of the third bumps is formed between two adjacent second bumps 69. .

Referring to FIG. 12E, the second bumps 69 are formed on the first bumps 58. Thereafter, the third bumps 71 are formed on the second bumps 69 vertically and between the first insulating layers 60 between two adjacent bumps 69. 12F to 12H, the first bump and the third bump are arbitrarily stacked on each other to make the pixel electrode non-uniform. 12I and 12D, the second bumps 69 and the third bumps 71 are superimposed on the first bumps to obtain the necessary coarse reflective surface.

The roughness of the pixel electrode can be arbitrarily adjusted by stacking three types of bumps 58, 69, and 71, but the necessary curved surface can be readjusted using a covering layer before forming the pixel electrode. Referring to FIG. 13, after the passivation layer 76 is deposited, the cover layer 80 is coated thereon, and then the pixel electrode 78 is formed. In the region A, a first bump of the first metal layer is formed in the substrate 50. Thus, the first insulating layer 60 and the passivation layer 76, which are later deposited, can duplicate the shape of their upper surface. The cover layer 80 made of an organic material or the like can alleviate the curved surface, and can adjust the angle θ of the uneven surface.

12J, 12K and 12L, three types of bumps 58, 69 and 71 and a cover layer 80 are used to make the required non-uniform surface. In FIG. 12J, a first bump 58 is formed while etching the first metal layer. After depositing the first insulating layer 60, the second bump 69 made of the second insulating layer 66 and the third bump 71 made of the second metal layer 70 are perpendicular to the first bump 58. The third bump 71 is formed above the second bump 69 vertically and has a smaller size than the second bump 69. Similarly, the size of the second bumps 69 is smaller than the size of the first bumps 58. Thus, as shown in the figure, a stack of awl shapes can be obtained. The cover layer 80 formed in the awl-shaped stack can alleviate or adjust the required surface of the pixel electrode.

In Fig. 12K, the size of the first, second and third bumps 58, 69 and 71 are adjusted to form several stacks in the same manner. A third bump larger in size than the first and second bumps may be completely applied to extend beyond the second bumps 69 to the surface of the first insulating layer to mitigate the flexure. Therefore, after the cover layer 80 and the pixel electrode 78 are formed, the surface as shown in FIG. 12K can be obtained. In FIG. 12L, the size of the third bump 71 is adjusted between the sizes of the first bumps 58 and the second bumps 69 to cover the entirety of the second bumps 69 and the surface of the first insulating layer 60. Extends.

Third Embodiment (not shown)

The method described in the first embodiment can be applied to a process of forming a thin film transistor having an etch stopper. However, the feature of the present invention can be applied to a BCE type TFT-LCD without an etch stopper. The difference between the first embodiment and the third embodiment is that there is no etching step and the second insulating layer forming step described above.

That is, in the third embodiment, it is not necessary to form the second insulating layer on the semiconductor layer and the first insulating layer. Therefore, the second etching process for forming the etching stopper is not necessary. For this reason, the second bump described in the first embodiment is not formed. In the third embodiment, only the first bump and the third bump apply. However, the rough surface of the pixel electrode may be obtained by arbitrarily stacking the first bump and the third bump.

While the preferred embodiments of the invention have been described, it will be understood that various modifications can be made without departing from the spirit and scope of the invention.

The present invention can provide various advantages. First, the first, second, and third bumps used to roughen the pixel electrode are composed of a first metal layer, a second insulating layer, and a second metal layer, respectively, by an etching process. Thus, there is no need for additional photo reticles and etching processes to deposit and form photosensitive bumps as in the prior art. Therefore, the TFT-LCD manufacturing throughput can be maintained when the pixel electrode diffuser is manufactured by applying the present invention. Further, the shape and angle of the curved surface of the pixel electrode can be adjusted by using three types of bumps arbitrarily stacked, and by adjusting the size and the gap between each bump.

Those skilled in the art will understand that the above-described preferred embodiments are illustrative rather than limiting the present invention. It is intended to include an analogous arrangement with many variations that fall within the spirit and scope of the claims. For example, in the first and second embodiments, the etch stopper is used to prevent etch damage of the lower semiconductor layer. However, as described in the third embodiment, the present invention can also be applied to a BCE type process that saves one photomask to increase throughput. In addition, although only the bottom gate type thin film transistor has been described above, the feature may be applied to an upper gate type transistor process.

Claims (15)

delete In the method of manufacturing a TFT-LCD device having a rough pixel electrode, Forming a first metal layer on the substrate, Performing a first etching process of etching the first metal layer to form a gate structure, Forming a first insulating layer on the gate structure and the substrate; Forming a semiconductor layer on the first insulating layer over the gate structure, Forming a second insulating layer on the first insulating layer and the semiconductor layer, Performing a second etching process of etching the second insulating layer to form an etch stopper for the gate structure; Forming a second metal layer on the first insulating layer, the etch stopper, and the semiconductor layer; Performing a third etching process to etch the second metal layer to form a drain / source structure, Forming a passivation layer on said drain / source structure and said first insulating layer, and Forming a pixel electrode on the passivation layer to electrically connect the drain / source structure Including, At least one type of bump is formed on the substrate so that the passivation layer and the pixel electrode replicate the rough and uneven surface shape of the bump, and the bump is simultaneously formed into the first metal layer by the first etching process. A first bump to be formed, a second bump to be simultaneously formed into the second insulating layer by the second etching process, and a third bump to be simultaneously formed into the second metal layer by the third etching process. A method of manufacturing a TFT-LCD device having a rough pixel electrode. The method of claim 2, And said second insulating layer is made of silicon nitride. The method of claim 2, The first metal layer is selected from the group consisting of aluminum (Al), chromium (Cr), titanium (Ti), tungsten (W), tantalum (Ta), molybdenum (Mo), alloys, and combinations thereof. A method of manufacturing a TFT-LCD device having a rough pixel electrode. The method of claim 2, The second metal layer is composed of aluminum (Al), chromium (Cr), titanium (Ti), tungsten (W), tantalum (Ta), molybdenum (Mo), alloys, and combinations thereof. The method of manufacturing a TFT-LCD device having a rough pixel electrode, characterized in that it is selected from. delete delete delete delete delete delete In the method of manufacturing a TFT-LCD device having a rough pixel electrode acting as a diffuser, Forming a first metal layer on the substrate, Performing a first etching process of etching the first metal layer to form first bumps and a gate structure on the substrate; Forming a first insulating layer on the substrate to cover the gate structure and the first bumps, Forming a semiconductor layer on the first insulating layer over the gate structure, Forming a second insulating layer on the semiconductor layer and the first insulating layer, Performing an etching process of etching the second insulating layer to form an etching stopper on the gate structure; Forming a second metal layer on the etch stopper, the semiconductor layer and the first insulating layer; Performing a third etching process of etching the second metal layer to form a drain / source structure next to the etching stopper; Forming a passivation layer on the drain / source structure and the first insulating layer, the portion being exposed, and Forming a pixel electrode on the passivation layer to electrically connect the drain / source structure Including; The passivation layer and the pixel electrode have a rough surface shape that is duplicated in the first bump, and the second etching process simultaneously forms a second bump formed of the second insulating layer on the first insulating layer. The third etching process simultaneously forms a third bump made of the second metal layer on the first insulating layer, And forming a cover layer on the passivation layer to adjust the angle of the pixel electrode. delete delete delete