INDIUM TIN OXIDE (ITO) LAYER FORMING

• US 20100035030A1
• Filed: 08/08/2008
• Published: 02/11/2010
• Est. Priority Date: 08/08/2008
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Zhong, John Z., Huang, Lili
• Granted Patent: US 8,049,862 B2
• Time in Patent Office: Days
• US Class Current: 428/201
• CPC Class Codes: C23C 14/086 of zinc, germanium, cadmium, indium, tin, thallium or bismuth
• CPC Class Codes: C23C 14/5806 Thermal treatment
• CPC Class Codes: C23C 14/5813 using lasers
• CPC Class Codes: G02F 1/1303 Apparatus specially adapted to the manufacture of LCDs
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G02F 1/133388 with constructional differences between the display region and the peripheral region
• CPC Class Codes: G02F 2201/122 having a particular pattern
• CPC Class Codes: G02F 2201/38 Anti-reflection arrangements
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes
• CPC Class Codes: H01L 31/1884 Manufacture of transparent electrodes, e.g. TCO, ITO
• CPC Class Codes: Y02E 10/50 Photovoltaic [PV] energy
• CPC Class Codes: Y10T 428/24851 Intermediate layer is discontinuous or differential
• CPC Class Codes: Y10T 428/24926 including ceramic, glass, porcelain or quartz layer

Abstract

A layer of material, such as crystalline indium tin oxide (ITO), is formed on top of a substrate by heating the material to a high temperature, while a temperature increase of the substrate is limited such that the temperature of the substrate does not exceed a predetermined temperature. For example, a layer including amorphous ITO can be deposited on top of the substrate, and the amorphous layer can be heated in a surface anneal process using radiation while limiting substrate temperature. Another process can pass electrical current through the amorphous ITO. In another process, the substrate is passed through a high-temperature deposition chamber quickly, such that a portion of a layer of crystalline ITO is deposited, while the temperature increase of the substrate is limited.

Claims

1. A method of forming a crystalline indium tin oxide (ITO) layer on top of a substrate, the method comprising:

heating ITO to a high temperature sufficient to form crystalline ITO; and

limiting a temperature increase of the substrate during the formation of the crystalline ITO layer.

2. The method of claim 1, further comprising:

depositing a layer including amorphous ITO on top of the substrate, wherein the heating ITO to a high temperature includes heating the layer including amorphous ITO.

3. The method of claim 2, wherein heating the layer including amorphous ITO includes:

applying electromagnetic (EM) radiation to the layer including amorphous ITO.

4. The method of claim 3, wherein a wavelength of the EM radiation is selected such that most of the EM radiation is absorbed by the amorphous ITO layer.

5. The method of claim 3, wherein the EM radiation is selected from the group consisting of laser light, ultraviolet (UV) radiation, and microwave radiation.

6. The method of claim 3, further comprising:

forming an intermediate layer between the layer including amorphous ITO and the substrate.

7. The method of claim 6, wherein the intermediate layer is reflects EM radiation at the wavelength of the EM radiation.

8. The method of claim 6, wherein the intermediate layer absorbs EM radiation at the wavelength of the EM radiation.

9. The method of claim 2, wherein heating the layer including amorphous ITO includes:

applying electrical current to the layer including amorphous ITO.

10. The method of claim 9, further comprising:

measuring the electrical resistance of the amorphous ITO layer; and

stopping the application of the electrical current when the measured electrical resistance reaches a predetermined threshold.

11. The method of claim 9, wherein applying the electrical current comprises:

applying a first electrical current during a first period of time;

stopping the application of the first electrical current during a second period of time; and

applying a second electrical current during a third period of time.

12. The method of claim 1, wherein heating ITO to a high temperature comprises

heating ITO during a high-temperature deposition onto the substrate, and limiting a temperature increase of the substrate comprises

applying the high-temperature deposition to the substrate for a first period of time during which a portion of the crystalline ITO layer is deposited,

removing the substrate from the high-temperature deposition for a second period of time during which a temperature of the substrate decreases, and

repeating the applying and the removing until the layer of crystalline ITO is formed.

13. The method of claim 12, wherein the high-temperature deposition is a physical vapor deposition.

14. The method of claim 1, further comprising:

including a temperature indicator with the substrate; and

reading the temperature indicator after forming the crystalline ITO layer.

34. The layer of crystalline ITO formed by the method of claim 1, the layer of crystalline ITO formed within a touch sensor panel.

35. The layer of crystalline ITO formed by the method of claim 1, the layer of crystalline ITO formed within a computing system.

15. A method of annealing a layer of material that is deposited on a substrate, the method comprising:

exposing the layer of material to electromagnetic (EM) radiation that has a wavelength that is absorbed by the material and that heats the material to an annealing temperature;

limiting a temperature increase of the substrate to less than a predetermined temperature by limiting the EM radiation exposure to a time duration profile of exposure and by setting at least one of a wavelength of the EM radiation, an intensity of the EM radiation, and an incident angle of the EM radiation.

16. A method of depositing a layer of material on top of a substrate at a high temperature, the method comprising:

passing the substrate through a high-temperature deposition chamber a plurality of times, wherein a portion of the layer of material deposited during each pass; and

limiting a temperature increase of the substrate to less than a predetermined temperature by limiting durations of the passes and by allowing a temperature of the substrate to decrease during time periods between passes.

17. An apparatus for forming a crystalline indium tin oxide (ITO) layer on top of a substrate, the apparatus comprising:

a heater that heats ITO to a high temperature sufficient to form crystalline ITO;

a controller that controls the heater such that a temperature increase of the substrate is limited to less than a predetermined temperature during the formation of the crystalline ITO layer.

18. The apparatus of claim 17, further comprising:

a low-temperature sputterer that deposits a layer including amorphous ITO on top of the substrate at a low temperature, wherein the heater heats the layer including amorphous ITO.

19. The apparatus of claim 18, wherein the heater is an electromagnetic (EM) radiation source that exposes the amorphous ITO layer to EM radiation.

20. The apparatus of claim 19, wherein the controller sets an output wavelength of the EM radiation source such that most of the EM radiation is absorbed by the amorphous ITO layer.

21. The apparatus of claim 19, wherein the EM radiation source is selected from the group consisting of a laser, an ultraviolet (UV) radiation source, and a microwave radiation source.

22. The apparatus of claim 19, further comprising:

an intermediate layer forming mechanism that forms an intermediate layer between the layer including amorphous ITO and the substrate.

23. The apparatus of claim 22, wherein the intermediate layer is reflects EM radiation at the wavelength of the EM radiation.

24. The apparatus of claim 22, wherein the intermediate layer absorbs EM radiation at the wavelength of the EM radiation.

25. The apparatus of claim 18, wherein the heater is a current source that applies electrical current to the layer including amorphous ITO.

26. The apparatus of claim 25, further comprising:

a detector that measures the electrical resistance of the amorphous ITO layer, wherein the controller stops the application of the electrical current when the measured electrical resistance reaches a predetermined threshold.

27. The apparatus of claim 25, wherein the controller controls the heater to apply a first electrical current during a first period of time, to stop the application of the first electrical current during a second period of time, and to apply a second electrical current during a third period of time.

28. The apparatus of claim 17, wherein the heater is a high-temperature deposition chamber system including a high-temperature deposition chamber, and heating ITO to a high temperature comprises

heating ITO during in the high-temperature deposition chamber to be deposited onto the substrate, and

the controller controls the high-temperature deposition chamber system to place the substrate in the high-temperature deposition chamber for a first period of time during which a portion of the crystalline ITO layer is deposited, to remove the substrate from the high-temperature deposition chamber for a second period of time during which a temperature of the substrate decreases, and to repeat the placing and the removing until the layer of crystalline ITO is formed.

29. The apparatus of claim 28, wherein the high-temperature deposition chamber is a physical vapor deposition chamber.

30. An apparatus for annealing a layer of material that is deposited on a substrate, the apparatus comprising:

an electromagnetic (EM) radiation source that exposes the layer of material to EM radiation that has a wavelength that is absorbed by the material and that heats the material to an annealing temperature;

a controller that limits a temperature increase of the substrate to less than a predetermined temperature by limiting the EM radiation exposure to a time duration profile of exposure and by setting at least one of a wavelength of the EM radiation, an intensity of the EM radiation, and an incident angle of the EM radiation.

31. An apparatus for depositing a layer of material on top of a substrate at a high temperature, the apparatus comprising:

a high-temperature deposition system that passes the substrate through a high-temperature deposition chamber a plurality of times, wherein a portion of the layer of material deposited during each pass; and

a controller that limits a temperature increase of the substrate to less than a predetermined temperature by limiting durations of the passes and by allowing a temperature of the substrate to decrease during time periods between passes.

32. A mobile telephone including a touch sensor panel containing a layer of crystalline ITO formed by a method comprising:

heating ITO to a high temperature sufficient to form crystalline ITO; and

limiting a temperature increase of the substrate during the formation of the crystalline ITO layer.

33. A digital media player including a touch sensor panel containing a layer of crystalline ITO formed by a method comprising:

heating ITO to a high temperature sufficient to form crystalline ITO; and

limiting a temperature increase of the substrate during the formation of the crystalline ITO layer.

36. A stackup of materials comprising:

a layer of glass covering a volume of liquid crystal;

a first layer of reflective material formed on the layer of glass; and

a first layer of crystalline indium tin oxide (ITO) formed on the layer of reflective material.

37. The stackup of claim 36, wherein the reflective material is substantially transparent to visible light and substantially reflective to an electromagnetic radiation that ITO substantially absorbs.

38. The stackup of claim 36, wherein the first layer of ITO is a layer of patterned, single-layer ITO for capacitive touch sensing.

39. The stackup of claim 36, further comprising:

a layer of insulating material formed on the layer of crystalline ITO; and

a second layer of crystalline ITO formed on the layer of insulating material.

40. The stackup of claim 39, wherein one of the first and second layers of crystalline ITO is a layer of patterned ITO that includes drive lines for capacitive touch sensing, and the other one of the first and second layers of crystalline ITO is a layer of patterned ITO that includes sense lines for capacitive touch sensing.

41. The stackup of claim 36, further comprising:

a layer of insulating material formed on the layer of crystalline ITO;

a second layer of reflective material formed on the layer of insulating material; and

a second layer of crystalline ITO formed on the second layer of reflecting material.

42. The stackup of claim 41, wherein one of the first and second layers of crystalline ITO is a layer of patterned ITO that includes drive lines for capacitive touch sensing, and the other one of the first and second layers of crystalline ITO is a layer of patterned ITO that includes sense lines for capacitive touch sensing.

43. The stackup of claim 36, the stackup formed within a touch screen.

44. A stackup of materials comprising:

a layer of glass covering a volume of liquid crystal;

a layer of absorbent material that absorbs electromagnetic (EM) radiation formed on the layer of glass; and

a layer of crystalline indium tin oxide (ITO) formed on the layer of absorbent material.

45. The stackup of claim 44, wherein the absorbant material is substantially transparent to visible light and substantially absorbant to an electromagnetic radiation that ITO substantially absorbs.

46. The stackup of claim 44, wherein the first layer of ITO is a layer of patterned, single-layer ITO for capacitive touch sensing.

47. The stackup of claim 44, further comprising:

a layer of insulating material formed on the layer of crystalline ITO; and

a second layer of crystalline ITO formed on the layer of insulating material.

48. The stackup of claim 47, wherein one of the first and second layers of crystalline ITO is a layer of patterned ITO that includes drive lines for capacitive touch sensing, and the other one of the first and second layers of crystalline ITO is a layer of patterned ITO that includes sense lines for capacitive touch sensing.

49. The stackup of claim 44, further comprising:

a layer of insulating material formed on the layer of crystalline ITO;

a second layer of absorbent material formed on the layer of insulating material; and

a second layer of crystalline ITO formed on the second layer of absorbent material.

50. The stackup of claim 49, wherein one of the first and second layers of crystalline ITO is a layer of patterned ITO that includes drive lines for capacitive touch sensing, and the other one of the first and second layers of crystalline ITO is a layer of patterned ITO that includes sense lines for capacitive touch sensing.

51. The stackup of claim 44, the stackup formed within a touch screen.