Method for fabrication liquid crystal display device and diffraction mask therefor

• US 20050142680A1
• Filed: 12/13/2004
• Published: 06/30/2005
• Est. Priority Date: 12/29/2003
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Philips LCD Company Limited (LG Display Co., Ltd.)
• Inventors: Jeoung, Hun, Jang, Jeong Woo, Ha, Yong Min
• Granted Patent: US 7,405,776 B2
• Time in Patent Office: Days
• US Class Current: 438/30
• CPC Class Codes: G02F 1/136213 Storage capacitors associated with the pixel electrode
• CPC Class Codes: G02F 1/136227 Through-hole connection of the pixel electrode to the active element through an insulation layer
• CPC Class Codes: G02F 1/136231 for reducing the number of lithographic steps
• CPC Class Codes: G02F 1/136236 using a grey or half tone lithographic process
• CPC Class Codes: H01L 27/1214 comprising a plurality of TFTs formed on a non-semiconducting substrate, e.g. driving circuits for AMLCDs
• CPC Class Codes: H01L 27/1274 using crystallisation of amorphous semiconductor or recrystallisation of crystalline semiconductor
• CPC Class Codes: H01L 27/1288 employing particular masking sequences or specially adapted masks, e.g. half-tone mask
• CPC Class Codes: H01L 29/66757 Lateral single gate single channel transistors with non-inverted structure, i.e. the channel layer is formed before the gate
• CPC Class Codes: H01L 29/78645 with multiple gate

Abstract

An LCD is fabricated using a diffraction mask with transmissive, semi-transmissive, and opaque regions. The semi-transmissive region permits formation of a transmission, reflection, or pixel electrode, depending on the type of LCD being fabricated, using the same masking process as that to produce contact holes in an insulating film and a conductive layer. Photoresist exposed through the semi-transmissive region is partially removed during developing that completely removes photoresist in the transmissive or opaque region. The contact holes are formed in the region in which the photoresist is completely removed, the photoresist and underlying conductive layer in the semi-transmissive region are then removed, and the remaining photoresist is stripped.

Claims

1. A method for fabricating an LCD, the method comprising:

forming an active pattern, a first insulation film and a gate electrode on a substrate;

injecting impurity ions into a region of the active pattern, using the gate electrode as a mask, to form source and drain regions;

forming a second insulation film on the substrate;

forming a transparent conductive film on the second insulation film;

removing a portion of the transparent conductive film and the first and second insulation films to form a transmission electrode and first and second contact holes exposing a portion of the source and drain regions;

forming source and drain electrodes on the substrate, the source electrode connected with the source region through the first contact hole, the drain electrode connected with the drain electrode through the second contact hole and connected with the transmission electrode;

forming a third insulation film on the substrate;

patterning the third insulation film to form a third contact hole exposing a portion of the drain electrode; and

forming a reflection electrode on the substrate, the reflection electrode connected with the drain electrode and connected with the transmission electrode.

2. The method of claim 1, wherein the active pattern comprises a polycrystalline silicon thin film.

3. The method of claim 2, wherein forming the polycrystalline silicon thin film comprises:

depositing an amorphous silicon thin film on the substrate; and

irradiating the amorphous silicon thin film with a laser beam to crystallize the amorphous silicon thin film.

4. The method of claim 1, further comprising using a diffraction mask to form the first and second contact holes and the transmission electrode.

5. The method of claim 1, wherein forming the first and second contact holes and the transmission electrode comprises:

coating a photoresist film on the second insulation film;

irradiating the photoresist film with light passing through a mask, the mask having a first transmission region that transmits a portion of the light, a second transmission region that transmits substantially all of the light and a blocking region that blocks the light;

developing the irradiated photoresist film to form a first photoresist film pattern with a first thickness at a first region corresponding to the first transmission region and a second photoresist film pattern with a second thickness at a second region corresponding to the blocking region;

removing a portion of the first and second insulation films and the transparent conductive film, using the first and second photoresist film patterns as a mask, to form first and second contact holes exposing a portion of the source and drain regions;

removing the first photoresist film pattern; and

patterning the transparent conductive film, using the second photoresist film pattern as a mask, to form the transmission electrode.

6. The method of claim 4, wherein the diffraction mask includes a diffraction pattern formed at a first transmission region, the diffraction pattern transmitting only a portion of light, the first and second contact holes and the transmission electrode formed in a region other than the first transmission region.

7. The method of claim 5, wherein the mask containing the first transmission region includes a diffraction pattern formed in the first transmission region.

8. The method of claim 4, wherein the diffraction mask includes a diffraction pattern in which slits are successively disposed in a horizontal or vertical direction.

9. The method of claim 5, wherein the mask containing the first transmission region includes a diffraction pattern in which slits are successively disposed in a horizontal or vertical direction.

10. The method of claim 8, wherein the diffraction mask includes:

a contact hole region; and

a concentric diffraction pattern formed around the contact hole region or a dot diffraction pattern.

11. The method of claim 9, wherein the mask containing the first transmission region includes:

a contact hole region; and

a concentric diffraction pattern around the contact hole region or a dot diffraction pattern.

12. The method of claim 4, wherein the diffraction mask includes a bar that partially blocks the light and a space through which the light is transmitted.

13. The method of claim 5, wherein the mask containing the first transmission region includes a bar that partially blocks the light and a space through which the light is transmitted.

14. The method of claim 12, wherein the bar or the space has a width of about 1 μ

m to about 2 μ

m.

15. The method of claim 13, wherein the bar or the space has a width of about 1 μ

m to about 2 μ

m.

16. The method of claim 5, wherein the first thickness is thinner than the second thickness.

17. The method of claim 1, wherein the transparent conductive film comprises indium tin oxide (ITO) or indium zinc oxide (IZO).

18. The method of claim 1, wherein the third insulation film comprises an organic material.

19. The method of claim 18, wherein the organic material comprises benzocyclobutene (BCB) or photo acryl.

20. The method of claim 1, wherein the reflector comprises aluminum.

21. The method of claim 1, wherein the impurity ions are group 5 elements.

22. The method of claim 1, wherein the impurity ions are group 3 elements.

23. The method of claim 1, further comprising forming a concavo-convex pattern at a surface of the third insulation film.

24. A method for fabricating an LCD, the method comprising:

forming an active pattern and a gate electrode on a substrate;

forming a passivation film and a transparent conductive film on the gate electrode;

forming contact holes and a transmission electrode using a single masking process, the contact holes exposing sides of the active pattern;

forming an opaque conductive film in the contact holes and on the transmission electrode and patterning the opaque conductive film to form a source electrode connected to a first side of the active pattern and a drain electrode connected to a second side of the active pattern and to the transmission electrode;

forming an organic film on the substrate and patterning the organic film to make a surface of the organic film concavo-convex;

patterning the concavo-convex organic film to form a contact hole exposing a portion of the drain electrode; and

forming an opaque metal film on the organic film and patterning the opaque metal film on the organic film to form a reflection electrode connected to the drain electrode and the transmission electrode.

25. The method of claim 24, wherein forming the contact holes exposing the sides of the active pattern and the transmission electrode comprises:

coating a photoresist film on the passivation film;

irradiating the photoresist film with light passing through a mask, the mask having a first transmission region that transmits a portion of the light, a second transmission region that transmits substantially all of the light and a blocking region that blocks the light;

developing the irradiated photoresist film to form a first photoresist film pattern with a first thickness at a first region corresponding to the first transmission region and a second photoresist film pattern with a second thickness at a second region corresponding to the blocking region;

removing a portion of passivation film and the transparent conductive film, using the first and second photoresist film patterns as a mask, to form contact holes exposing a portion of marginal portions of the active pattern;

removing the first photoresist film pattern; and

patterning the transparent conductive film, using the second photoresist film pattern as a mask, to form a transmission electrode.

26. A method for fabricating an LCD, the method comprising:

forming an active pattern, a first insulation film and a gate electrode on a substrate;

injecting impurity ions into a region of the active pattern, using the gate electrode as a mask, to form source and drain regions;

forming a second insulation film and a transparent conductive film on the substrate;

removing a portion of the transparent conductive film and the first and second insulation films to form a pixel electrode and first and second contact holes exposing a portion of the source and drain regions; and

forming source and drain electrodes, the source electrode connected with the source region through the first contact hole, the drain electrode connected with the drain electrode through the second contact hole and connected with the pixel electrode.

27. The method of claim 26, wherein the first and second contact holes and the pixel electrode are formed using a diffraction mask.

28. The method of claim 27, wherein the diffraction mask includes a diffraction pattern in which slits are successively disposed in a horizontal or vertical direction.

29. The method of claim 28, wherein the diffraction mask includes a diffraction pattern formed concentrically around a contact hole region or a dot diffraction pattern.

30. The method of claim 27, wherein the diffraction mask includes a bar that blocks light and a space through which light is transmitted.

31. The method of claim 30, wherein the bar or the space has a width of about 1 μ

m to about 2 μ

m.

32. A method for fabricating an LCD, the method comprising:

forming an active pattern, a first insulation film and a gate electrode on a substrate;

injecting impurity ions into a region of the active pattern, using the gate electrode as a mask, to form source and drain regions;

forming a second insulation film and an opaque conductive film on the substrate;

removing a portion of the opaque conductive film and the first and second insulation films to form a reflection electrode and first and second contact holes exposing a portion of the source and drain regions; and

forming source and drain electrodes on the substrate, the source electrode connected with the source region through the first contact hole, the drain electrode connected with the drain electrode through the second contact hole and connected with the reflection electrode.

33. The method of claim 32, further comprising using a diffraction mask to form the first and second contact holes and the reflection electrode.

34. The method of claim 33, wherein the diffraction mask includes a diffraction pattern in which slits are successively disposed in a horizontal or vertical direction.

35. The method of claim 34, wherein the diffraction mask comprises a concentric diffraction pattern around the contact hole region or a dot diffraction pattern.

36. The method of claim 33, wherein the diffraction mask comprises a bar that blocks light and a space through which light is transmitted.

37. The method of claim 36, wherein the bar or the space has a width of about 1 μ

m to about 2 μ

m.

38. A method for fabricating a display, the method comprising:

forming an insulating layer and a first conductive layer on a substrate of the display;

coating a photoresist film on the insulating and first conductive layers;

aligning a mask through which light impinging thereon is partially transmitted in a first region, substantially fully transmitted in a second region, and substantially blocked in a third region;

exposing the photoresist film to light passing through the mask;

developing the photoresist film such that photoresist of a first thickness remains in the first region and one of;

photoresist of a second thickness remains in the third region and no photoresist remains in the second region or photoresist of the second thickness remains in the second region and no photoresist remains in the third region;

etching through the insulating and first conductive layers in the region in which no photoresist remains to expose an underlying second conductive layer through contact holes;

removing the photoresist and underlying first conductive layer in the first region; and

removing the photoresist in the region in which the photoresist of the second thickness was developed.

39. The method of claim 38, wherein the mask comprises a diffraction pattern formed in the first region.

40. The method of claim 38, wherein the first conductive layer comprises a transparent conductive material.

41. The method of claim 38, further comprising forming a first opaque conductive layer in the contact holes.

42. The method of claim 41, further comprising coating the first opaque conductive layer with a passivation film, forming a contact hole in the passivation film and forming a second opaque conductive layer on the passivation layer such that the second opaque conductive layer contacts the first opaque conductive layer and the first conductive layer.

43. The method of claim 38, further comprising forming a semiconductor layer under the second conductive layer.

44. The method of claim 43, further comprising forming a gate line and a data line on the substrate, wherein the second conductive layer is a storage electrode and the semiconductor layer extends from the data line, under the gate line to under the storage electrode.