Liquid crystal display device and method of manufacturing the same

Abstract

The present invention discloses a method of manufacturing a liquid crystal display device including a first photolithography process forming a gate electrode on a substrate; a second photolithography process including: a) depositing sequentially a gate insulating layer, first and second semiconductor layers, and a metal layer; b) applying a first photoresist on the metal layer; c) aligning a first photo mask with the substrate; d) light exposing and developing the first photoresist to produce a first photoresist pattern; e) etching the metal layer using a first etchant, the first etchant ashing the first photoresist pattern on a predetermined portion of the metal layer to produce a second photoresist pattern, thereby exposing the predetermined portion of the metal layer; and f) etching the gate insulating layer, the first and second semiconductor layer, and the predetermined portion of the metal layer using a second etchant according to the second photoresist pattern to form source and drain electrodes, an ohmic contact layer, and an active area; a third photolithography process forming a passivation film and a contact hole; and a fourth photolithography process forming a pixel electrode connecting with the drain electrode through the contact hole.

1. A method of manufacturing a liquid crystal display device, comprising:
 a first photolithography process forming a gate electrode on a substrate;  
 a second photolithography process including: 
 a) depositing sequentially a gate insulating layer, a semiconductor layer, and a metal layer;  
 b) applying a first photoresist on the metal layer;  
 c) aligning a first photo mask with the substrate;  
 d) light exposing and developing the first photoresist to produce a first photoresist pattern;  
 e) etching the metal layer using a first etchant, the first etchant ashing the first photoresist pattern on a portion of the metal layer to produce a second photoresist pattern, thereby exposing the portion of the metal layer; and  
 f) etching the gate insulating layer,  the semiconductor layer, and the portion of the metal layer using a second etchant according to the second photoresist pattern to form source and drain electrodes, an ohmic contact layer, and an active area;  
 
 a third photolithography process forming a passivation film and a contact hole; and  
 a fourth photolithography process forming a pixel electrode connecting with the drain electrode through the contact hole.  
 
     
     
       2. The method of  claim 1 , wherein the first etchant includes Cl 2 /O 2  gas. 
     
     
       3. The method of  claim 2 , wherein the second etchant includes SF 6 /HCl gas. 
     
     
       4. The method of  claim 2 , wherein the second etchant includes SF 6 /H 2 /Cl 2  gas. 
     
     
       5. The method of  claim 1 , wherein the semiconductor layer includes first and second semiconductor layers. 
     
     
       6. The method of  claim 5 , wherein the first semiconductor layer includes amorphous silicon. 
     
     
       7. The method of  claim 5 , wherein the second semiconductor layer includes doped amorphous silicon. 
     
     
       8. The method of  claim 1 , wherein the source and drain electrodes are made of a metal selected from a group consisting of Cr, Mo, Al, and Al alloy. 
     
     
       9. The method of  claim 8 , wherein the semiconductor layer includes first and second semiconductor layers. 
     
     
       10. The method of  claim 9 , wherein the first semiconductor layer includes amorphous silicon. 
     
     
       11. The method of  claim 9 , wherein the second semiconductor layer includes doped amorphous silicon. 
     
     
       12. The method of  claim 1 , wherein the pixel electrode includes indium tin oxide. 
     
     
       13. The method of  claim 12 , wherein the semiconductor layer includes first and second semiconductor layers. 
     
     
       14. The method of  claim 13 , first semiconductor layer includes amorphous silicon. 
     
     
       15. The method of  claim 13 , wherein the second semiconductor layer includes doped amorphous silicon. 
     
     
       16. A method of manufacturing a thin film transistor of a liquid crystal display device, comprising:
   forming a gate electrode on substrate; and        forming a gate insulating layer, a semiconductor layer and source and drain electrodes using a photolithography process including:        forming a gate insulating layer a semiconductor layer, and a metal layer;        forming a photoresist on the metal layer;        light exposing and developing the photoresist to produce a first photoresist pattern, wherein the first photoresist pattern includes a central portion having a first thickness and adjacent side portions having a second thickness, the first thickness being smaller than the second thickness;        selectively removing the metal layer using the first photoresist pattern;        removing the central portion of the first photoresist pattern to form a second photoresist pattern;        selectively removing the semiconductor layer using the second photoresist pattern;        selectively removing the metal layer corresponding to the central portion of the photoresist pattern; and        selectively removing the semiconductor layer corresponding to the central portion of the photoresist pattern.     
     
     
       17. The method of  claim 16 , wherein light exposing and developing the photoresist to produce the photoresist first pattern includes using a diffraction light exposure technique. 
     
     
       18. The method of  claim 16 , wherein the metal layer is selectively removed using a dry etch technique. 
     
     
       19. The method of  claim 18 , wherein the dry etch technique uses a gas including Cl 2   /O   2    gas.   
     
     
       20. The method of  claim 16 , wherein the semiconductor layer is selectively removed using a dry etch technique. 
     
     
       21. The method of  claim 20 , wherein the dry etch technique uses a gas including fluorine and chlorine. 
     
     
       22. The method of  claim 21 , wherein the gas includes SF 6   /HCl.   
     
     
       23. The method of  claim 21  wherein the gas includes SF 6   /H   2   /Cl   2 . 
     
     
       24. The method of  claim 16 , wherein the semiconductor layer includes first and second semiconductor layers. 
     
     
       25. The method of  claim 24 , wherein the first semiconductor layer includes amorphous silicon. 
     
     
       26. The method of  claim 24 , wherein the second semiconductor layer includes doped amorphous silicon. 
     
     
       27. The method of  claim 16 , wherein the source and drain electrodes are made of a metal selected from the group consisting of Cr, Mo, Al, and Al alloy. 
     
     
       28. The method of  claim 16 , wherein removing the central portion of the first photoresist pattern exposes the metal layer. 
     
     
       29. A method of manufacturing a thin film transistor of a liquid crystal display device, comprising:
   forming a gate electrode on a substrate;        forming a gate insulating layer, a first semiconductor layer, a second semiconductor layer and source and drain electrodes using a photolithography process including:        forming a gate insulating layer, a first semiconductor layer, a second semiconductor layer and a metal layer;        forming a photoresist on the metal layer;        positioning a photo mask above the substrate;        light exposing and developing the photoresist to produce a photoresist pattern, wherein the photoresist pattern includes a central portion having a first thickness and adjacent side portions having a second thickness, the first thickness being smaller than the second thickness;        selectively removing the metal layer using the photoresist pattern;        selectively removing the first and second semiconductor layers;        selectively removing the metal layer beneath the central portion of the photoresist pattern having the first thickness to separate the metal layer into a first part spaced from a second part, the first part corresponding to the source electrode and the second part corresponding to the drain electrode; and        selectively removing the first semiconductor layer corresponding to the space between the first and second parts of the metal layer.     
     
     
       30. The method of  claim 29 , wherein the central portion of the photoresist is removed prior to selectively removing the first and second semiconductor layers. 
     
     
       31. A method of manufacturing a liquid crystal display device, comprising:
   forming a thin film transistor and a pixel electrode coupled to the thin film transistor; and        forming the thin film transistor including:        forming a gate electrode on a substrate;        forming a gate insulating layer, a semiconductor layer and source and drain electrodes using a photolithography process including:        forming a gate insulating layer, a semiconductor layer, and a metal layer;        forming a photoresist on the metal layer;        positioning a photo mask above the substrate;        light exposing and developing the photoresist to produce a photoresist pattern, wherein the photoresist pattern includes a central portion having a first thickness and a side portion having a second thickness, the first thickness being smaller than the second thickness;        selectively removing the metal layer using the photoresist pattern;        removing the central portion of the photoresist pattern having a first thickness;        selectively removing the semiconductor layer;        selectively removing the metal layer corresponding to the central portion of the photoresist pattern; and        selectively removing the semiconductor layer corresponding to the central portion of the photoresist pattern.     
     
     
       32. The method of  claim 31 , further comprising forming a passivation film having a contact hole over the source and drain electrodes, wherein the pixel electrode is formed on the passivation layer and contacting the drain electrode through the contact hole. 
     
     
       33. The method of  claim 31 , wherein the pixel electrode directly contacts the drain electrode. 
     
     
       34. The method of  claim 31 , wherein the pixel electrode includes indium tin oxide. 
     
     
       35. A method of manufacturing a liquid crystal display device, comprising:
   forming a thin film transistor and a pixel electrode coupled to the thin film transistor;        forming the thin film transistor including:        forming a gate electrode on a substrate;        forming a gate insulating layer, a first semiconductor layer, a second semiconductor layer and a metal layer;        forming a photoresist on the metal layer;        positioning a photo mask above the substrate;        light exposing and developing the photoresist to produce a photoresist pattern, wherein the photoresist pattern includes a central portion having a first thickness and a side portion having a second thickness, the first thickness being smaller than the second thickness;        selectively removing the metal layer using the photoresist pattern;        selectively removing the first and second semiconductor layers;        selectively removing the metal layer beneath the central portion of the photoresist pattern having the first thickness to separate the metal layer into a first part spaced from a second part, the first part corresponding to the source electrode and the second part corresponding to the drain electrode; and        selectively removing the first semiconductor layer corresponding to the space between the first and second parts of the metal layer.     
     
     
       36. The method of  claim 35 , wherein the central portion of the photoresist is removed prior to selectively removing the first and second semiconductor layers. 
     
     
       37. A method of manufacturing a liquid crystal display device, comprising:
   forming a gate electrode on a substrate;        forming a gate insulating layer, a semiconductor layer and source and drain electrodes using a photolithography process including:        forming a gate insulating layer, a semiconductor layer, and a metal layer;        forming a photoresist on the metal layer;        positioning a photo mask above the substrate;        light exposing and developing the photoresist to produce a photoresist pattern, wherein the photoresist pattern includes a central portion having a first thickness and adjacent side portions having a second thickness, the first thickness being smaller than the second thickness;        selectively removing the metal layer using the photoresist pattern;        removing the central portion of the photoresist pattern having the first thickness to expose the metal layer;        selectively removing the semiconductor layer;        selectively removing the metal layer corresponding to the central portion of the photoresist pattern;        selectively removing the semiconductor layer corresponding to the central portion of the photoresist pattern;        forming a passivation film having a contact hole over the source and drain electrodes; and        forming a pixel electrode contacting the drain electrode through the contact hole.     
     
     
       38. A method of manufacturing a thin film transistor of a liquid crystal display device, comprising:
   forming a gate electrode on a substrate;        forming a gate insulating layer, a semiconductor layer, and a metal layer over the gate electrode;        forming a photoresist over the metal layer, the photoresist including a central portion having a first thickness and a side portion having a second thickness, the first thickness being smaller than the second thickness; and        selectively removing the metal layer and the semiconductor layer including portions of the metal layer below the central portion of the photoresist to form source and drain electrodes and a channel.     
     
     
       39. The method of  claim 38 , wherein the semiconductor layer includes a first semiconductor layer and a second semiconductor layer on the first semiconductor layer. 
     
     
       40. The method of  claim 39 , further comprising selectively removing the second semiconductor layer corresponding to the central portion of the photoresist. 
     
     
       41. The method of  claim 39 , wherein the first semiconductor layer includes amorphous silicon and the second semiconductor layer includes doped amorphous silicon. 
     
     
       42. The method of  claim 38 , wherein the metal layer is selectively removed using a dry etch technique. 
     
     
       43. The method of  claim 42 , wherein the dry etch technique uses a gas including Cl 2   /O   2    gas.   
     
     
       44. The method of  claim 38 , wherein the semiconductor layer is selectively removed using a dry etch technique. 
     
     
       45. The method of  claim 44 , wherein the dry etch technique uses a gas including fluorine and chlorine. 
     
     
       46. The method of  claim 45 , wherein the gas includes SF 6   /HCl.   
     
     
       47. The method of  claim 45 , wherein the gas includes SF 6   /H   2   /Cl   2 . 
     
     
       48. The method of  claim 38 , wherein the source and drain electrodes are made of a metal selected from the group consisting of Cr, Mo, Al, and Al alloy. 
     
     
       49. A method of manufacturing a thin film transistor of a liquid crystal display device, comprising:
   forming a gate electrode on a substrate;        forming a gate insulating layer, a first semiconductor layer, a second semiconductor layer and source and drain electrodes using a photolithography process including:        sequentially forming the gate insulating layer, the first semiconductor layer, the second semiconductor layer and the metal layer;        forming a photoresist on the metal layer;        positioning a photo mask above the substrate;        light exposing and developing the photoresist to produce a photoresist pattern, wherein the photoresist pattern includes a central portion having a first thickness and adjacent side portions having a second thickness, the first thickness being smaller than the second thickness;        selectively removing the metal layer using the photoresist pattern;        selectively removing the first and second semiconductor layers;        selectively removing a portion of the metal layer beneath the central portion of the photoresist pattern to separate the metal layer into a first part spaced from a second part, the first part corresponding to the source electrode and the second part corresponding to the drain electrode; and        selectively removing the first semiconductor layer corresponding to the space between the first and second parts of the metal layer.     
     
     
       50. The method of  claim 49 , wherein the central portion of the photoresist is removed prior to selectively removing the first and second semiconductor layers.