KR950007356B1 - Making method of tft for lcd - Google Patents

Abstract

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Description

Thin film transistor of liquid crystal display and manufacturing method

1 is a cross-sectional view of a thin film transistor of a conventional liquid crystal display device.

2 is a cross-sectional view of a thin film transistor of a liquid crystal display according to the present invention.

3 (a) to 3d are manufacturing process diagrams of the thin film transistor of the liquid crystal display device according to the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film transistor of a liquid crystal display device and a method of manufacturing the same. In particular, the process is simple by forming a thin film transistor surrounded by an insulating film, and the reliability of the liquid crystal display device can be improved by improving step coverage of the laminated films. A thin film transistor of a liquid crystal display device and a manufacturing method thereof.

Currently, liquid crystal displays (hereinafter referred to as LCDs), which are widely used in laptop tops, notebook computers, and portable TVs, consume less power than conventional cathode ray tubes. There is an advantage that can be reduced to light and short, the range of use is gradually widening. In accordance with the trend of large-sized and high-definition LCDs, thin film transistors (hereinafter referred to as TFTs), which are used as switching elements of LCDs, miniaturization of metal wiring, low-resistance metals, selection of materials, and step coverage of laminated films forming TFTs Improvements in ste coverage have become important tasks. In addition, in the metal wiring, the thickness or width of the metal wiring is inversely proportional to the resistance and cannot be reduced to an appropriate level or less. Therefore, there is a problem that the step coverage of the subsequent laminated film is deteriorated due to the step between the substrate and the metal wiring. Therefore, a method of burying the metal wiring on the insulating substrate or inclining etching is performed.

1 is a cross-sectional view of a thin film transistor of a conventional liquid crystal display device, which is an Inverted Starered TFT having a gate electrode 13 buried in an insulating layer 12. The gate electrode 13 is formed of a metal such as Al or Cr on the glass substrate 11, and the insulating layer 12 is formed on both side walls of the gate electrode 13 at the same height as the gate electrode 13. Formed. A gate insulating film 14 made of silicon oxide or silicon nitride is formed on the surface of the insulating layer 12 and the gate electrode 13, and a semiconductor layer 15 made of amorphous silicon is formed on the gate electrode 13. (14) It is formed on the surface. In addition, the semiconductor layer 15 and the gate electrode 13 on the gate insulating film 14 are formed on the surface. In addition, a source electrode 17 is formed of a metal such as Cr, Al, or Ta on the semiconductor layer 15 and the gate insulating layer 14, and the semiconductor layer 15 is spaced apart from the source electrode 17 by a predetermined distance. ), The drain electrode 18 is formed so as to overlap the gate insulating film 14. A high concentration semiconductor layer 16 for ohmic contact is disposed on the contact portion of the source electrode 17, the drain electrode 18, and the semiconductor layer 15.

The TFT of the above-described conventional liquid crystal display device has a gate electrode buried in an insulating film to remove the terminal by the gate electrode, thereby improving the step coverage of the subsequent stacked films such as the gate insulating film, the semiconductor layer, the source electrode, and the drain electrode. Three etching processes are required: a first etching process for forming a groove in which a gate electrode is to be formed in a layer, a second etching process for patterning a semiconductor electrode, and a third etching process for patterning a source and a drain electrode. There was this complicated issue.

In addition, during the semiconductor layer patterning process, the surface of the semiconductor layer is contaminated to reduce the reliability of the TFT, and the step coverage of the source and drain electrodes is degraded due to the step of semiconductor application.

Accordingly, the present invention provides a liquid crystal display TFT and a method of manufacturing the same, which can simplify the manufacturing process, prevent contamination of the surface of the semiconductor layer, and improve the reliability of the TFT by improving the step coverage of the source and drain electrodes. have.

In order to achieve the above object, the present invention is a thin film transistor of a liquid crystal display device formed on an insulating substrate, a glass insulating substrate, a gate electrode and a gate insulating film sequentially stacked on the insulating substrate And a semiconductor layer, a high concentration semiconductor layer formed at both ends of the semiconductor layer, an insulating layer formed to surround side surfaces of the gate electrode, the gate insulating film, and the semiconductor layer, a source formed on the surface of the high concentration semiconductor layer and the insulating layer, The thin film transistor of the liquid crystal display device which consists of a drain electrode is characterized by the above-mentioned. In addition, the present invention provides a method of manufacturing a thin film transistor of a liquid crystal display device, comprising the steps of forming a first insulating layer on the entire surface of the insulating substrate, and a portion of the first insulating layer exposed on the first insulating layer. Forming a photoresist pattern, forming a groove by removing a predetermined depth of the first insulating layer exposed by the second photoresist pattern, and forming a groove on the entire surface of the structure; Forming a layer and a highly concentrated semiconductor layer sequentially; forming a first conductive layer, a second insulating layer, and a semiconductor layer on the first photoresist pattern and the first photoresist pattern; and a second surface on the entire surface of the structure. Forming a conductive layer, forming a second photoresist pattern so that the channel region of the semiconductor layer is exposed on the second conductive layer, and a second conductive layer and a high concentration semiconductor exposed by the second photoresist pattern First layer sequentially Thereby, a method of manufacturing a thin film transistor of a liquid crystal display device comprising a process of removing a second photoresist pattern after forming a source and a drain electrode.

Hereinafter, a thin film transistor and a method of manufacturing the liquid crystal display according to the present invention will be described in detail with reference to the accompanying drawings.

2 is a cross-sectional view of a thin film transistor of the liquid crystal display according to the present invention.

On a predetermined portion of the insulating substrate 21 made of glass material, a gate electrode 25 having a thickness of about 2000 to 4000 m is formed of a metal such as Al, Cr, Ta, or the like. A gate insulating film 26 having a thickness of about 1000 to 2000 micrometers is formed on the gate electrode 25 with silicon oxide or silicon nitride. In this case, in order to prevent defects on the interface between the gate electrode 25 and the gate insulating film 26, the gate electrode 25 may be anodized to a predetermined thickness to form an anodized film, and then the gate insulating film 26 may be formed. Subsequently, polycrystalline silicon (hereinafter referred to as Poly-Si), amorphous silicon (hereinafter referred to as a-SI), or hydrogenated amorphous form (hereinafter referred to as a-Si: H) on the surface of the gate insulating film 26, etc. The semiconductor layer 27 of about 2000-3000 micrometers in thickness is formed. Subsequently, an insulating layer is formed on the side surfaces of the gate electrode 25, the gate insulating layer 26, and the semiconductor layer 27 by a glass insulating material such as silicon oxide, silicon nitride or BPSG (Boro-Phospho Silicate Glass). (22) is formed. The thickness of the insulating layer 22 is about the same as the sum of the thicknesses of the gate electrode 25, the gate insulating film 26, and the semiconductor layer 27.

Subsequently, high-concentration semiconductor layers 28 are formed at both ends of the semiconductor layer 27 at a thickness of about 300 to 500 kV, such as poly-Si, a-Si, a-Si: H, and the like, which are heavily doped with impurities. The high concentration semiconductor layer 27 is for ohmic contact between the semiconductor layer 27 and the electrodes. Subsequently, a source electrode 31 and a drain electrode 32 are formed on metals such as Al, Cr, Ta, and W on the high concentration semiconductor layer 27 and the insulating layer 22. As described above, since the thin film transistor buried in the insulating layer 22 does not have a step between each layer, the step coverage may not be deteriorated, thereby improving reliability of the thin film transistor.

3 (a) to 3d are process charts of the thin film transistor of the liquid crystal display according to the present invention. In particular, it is a manufacturing process diagram of a reverse staggered TFT.

Referring to FIG. 3 (a), the insulating layer 22 having a thickness of about 5000 to 8000 Pa of silicon oxide or silicon nitride is formed on the surface of the glass insulating substrate 21 by physical vapor deposition or chemical vapor deposition. Next, a first photoresist pattern 23 is formed on the upper surface of the insulating layer 22 so that a part of the insulating layer 22 is exposed. Next, the insulating layer 22 exposed by the first photoresist pattern 23 is removed by a dry or wet etching method to form the grooves 24.

Referring to FIG. 3 (b), the gate electrode 25 having a thickness of about 2000 to 4000 microns, the gate insulating film 26 having a thickness of about 1000 to 2000 microns, by physical vapor deposition or chemical vapor deposition on the entire surface of the structure, The semiconductor layer 27 having a thickness of about 2000 to 3000 mW and the high concentration semiconductor layer 28 of about 300 to 500 mW are sequentially formed. In this case, the gate electrode 25 is formed of a metal such as Al, Cr or Ta, and the semiconductor layer 27 is formed of poly-Si, a-Si or a-Si: H, and the like, and has a high concentration of the semiconductor layer 28. ) Is formed of poly-Si, a-Si, or a-Si: H, which is doped with a high concentration of P or n-type impurities. In this case, the thickness of the groove 23 formed in the insulating layer 22 and the thickness of the gate insulating layer 26 and the semiconductor layer 27 with the gate electrode 25 are approximately the same. In addition, the upper surface of the gate electrode 25 when the gate electrode 25 is an anodized metal in order to prevent defects such as dislocations from occurring at the interface between the gate electrode 25 and the gate insulating film 26. Is formed by anodizing a predetermined thickness to form an anodic oxide film, and then the gate insulating film 26 may be formed.

Referring to FIG. 3 (c), the gate electrode 25, the gate insulating film 26, the semiconductor layer 27, and the high concentration semiconductor layer 28 that are sequentially stacked on the first photoresist film pattern 23 are typically used. The gate electrode 25, the gate insulating layer 26, the semiconductor layer 27, and the high concentration semiconductor layer 28 having the grooves 24 of the insulating layer 23 filled out are removed by the lift off method. Subsequently, the conductive layer 29 may be formed on the surface of the insulating layer 22 and the high concentration semiconductor layer 29 by a metal such as Al, Ta, Cr, or W by a method such as physical vapor deposition or chemical vapor deposition. ). Next, a second photoresist pattern 30 is formed on the upper surface of the conductive layer 29 to expose the channel region of the semiconductor layer 27.

Referring to FIG. 3 (d), the conductive layer 29 and the high concentration semiconductor layer 28 exposed by the second photoresist layer pattern 30 may be sequentially removed by a dry or wet etching method. The source electrode 31 and the drain electrode 32 are formed.

As described above, the present invention forms the thin film transistor of the liquid crystal display device so as to be buried in the insulating layer to improve the step coverage of the TFT, and performs only one lift-off process and one photo etching process. The defect generation of the interface, the highly concentrated semiconductor layer and the source and drain electrodes is prevented.

Therefore, this invention has the advantage of simplifying the TFT manufacturing process of the liquid crystal display device and improving the reliability of the TFT.

Claims (4)

A method of manufacturing a thin film transistor of a liquid crystal display device, the method comprising: forming an insulating layer on an entire surface of an insulating substrate; forming a first photosensitive film pattern on the insulating layer to expose a portion of the insulating layer; Forming a groove by removing a predetermined depth of the insulating layer exposed by the photosensitive film pattern, sequentially forming a gate electrode, a gate insulating film, a semiconductor layer, and a high concentration semiconductor layer on the entire surface of the structure; and the first photosensitive film Removing a gate electrode, a gate insulating film, a semiconductor layer and a high concentration semiconductor layer on the pattern and the first photoresist pattern, forming a conductive layer on the entire surface of the structure, and a channel region of the semiconductor layer on the conductive layer. Forming a second photoresist pattern so as to expose the photoresist, and sequentially removing the second conductive layer and the high concentration semiconductor layer exposed by the second photoresist pattern. Method for manufacturing a thin film transistor over the source and drain electrodes after forming the liquid crystal comprising a step of removing the second photosensitive film pattern display device. 2. The method of claim 1, wherein the insulating layer etching process is performed by one etching method selected from the group consisting of a dry or a wet etching method. The method of claim 1, further comprising: anodizing a part of the first conductive layer after the first conductive layer forming step to form an anodized film. The method of manufacturing a thin film transistor of a liquid crystal display device according to claim 1, wherein the step of removing the gate electrode, the gate insulating film, the semiconductor layer, and the highly concentrated semiconductor layer on the first photoresist pattern and the first photoresist pattern is performed by a normal lift-off process.