Indium tin oxide (ITO) layer forming

• US 8,049,862 B2
• Filed: 08/08/2008
• Issued: 11/01/2011
• Est. Priority Date: 08/08/2008
• Status: Expired due to Fees

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Zhong, John Z., Huang, Lili
• Primary Examiner(s): Healy; Brian
• Application Number:
  US12/189,133
• Publication Number:
  US 20100035030A1
• Time in Patent Office: 1,180 Days
• Field of Search: 349/187, 313/506, 438/30, 118/696, 427/419.2, 427/255.23, 428/201, 428/697, 428/426, 428/210
• US Class Current: 349/187
• 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 nonconductive substrate, the method comprising:

forming a layer including amorphous ITO on top of the substrate;

heating the layer including amorphous ITO to a first temperature, the first temperature being sufficient to form crystalline ITO from at least a portion of the amorphous ITO, by applying electrical current to the layer including amorphous ITO, such that a temperature of the substrate remains less than the first temperature during the formation of the crystalline ITO.

2. The method of claim 1, further comprising:

measuring the electrical resistance of the layer including amorphous ITO during the application of the electrical current; and

modifying the application of the electrical current based on the measured electrical resistance.

3. The method of claim 1, wherein applying the electrical current includes 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, after the first period of time, and applying a second electrical current during a third period of time, after the second period of time.

15. The method of claim 1, wherein applying the electrical current includes varying one of a power level of the electrical current and a frequency of the electrical current during the application of the electrical current.

16. The method of claim 15, wherein applying the electrical current includes one of ramping up the power level at a beginning of the application of the electrical current and ramping down the power level at an end of the application of the electrical current.

17. The method of claim 2, wherein modifying the application of the electrical current includes modifying one of an amount of the electrical current and a timing of the application of the electrical current.

18. The method of claim 17, wherein modifying the timing of the application of the electrical current includes stopping the application of the electrical current when the measured electrical resistance reaches a predetermined threshold.

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

heating ITO to a first temperature during a deposition of the ITO onto the substrate, the first temperature being sufficient to form crystalline ITO on the substrate;

applying the deposition to the substrate for a first period of time during which a portion of the crystalline ITO layer is deposited on the substrate, such that a temperature of the substrate remains less than the first temperature during the first period;

removing the substrate from the deposition for a second period of time, after the first period of time, during which the temperature of the substrate decreases; and

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

5. The method of claim 4, wherein the deposition is a physical vapor deposition.

6. 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 a wavelength of the EM radiation, an intensity of the EM radiation, and an incident angle of the EM radiation.

19. The method of claim 6, wherein the incident angle of the EM radiation is within a range between and including a grazing angle and a 45 degree angle.

7. 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 is 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.

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

a current source controller that applies electrical current to a layer including amorphous ITO on top of the nonconductive substrate, wherein the layer including amorphous ITO is heated to a first temperature, the first temperature being sufficient to form crystalline ITO from at least a portion of the amorphous ITO, and a temperature of the substrate remains less than the first temperature during the formation of the crystalline ITO.

9. The apparatus of claim 8, further comprising:

a detector that measures the electrical resistance of the layer including amorphous ITO during the application of the electrical current, wherein the controller modifies the application of the electrical current based on the measured electrical resistance.

10. The apparatus of claim 8, wherein the controller controls the current source 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, after the first period of time, and to apply a second electrical current during a third period of time, after the second period of time.

20. The apparatus of claim 8, wherein the controller varies one of a power level of the electrical current and frequency of the electrical current during the application of the electrical current.

21. The apparatus of claim 20, wherein application of the the electrical current by the controller includes one of ramping up the power level at a beginning of the application of the electrical current and ramping down the power level at an end of the application of the electrical current.

22. The apparatus of claim 9, wherein the modifying of the application of the electrical current by the controller includes modifying one of an amount of the electrical current and a timing of the application of the electrical current.

23. The apparatus of claim 22, wherein the modifying of the timing of the application of the electrical current by the controller includes stopping the application of the electrical current when the measured electrical resistance reaches a predetermined threshold.

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

a deposition chamber system that heats ITO to a first temperature in a deposition chamber, and deposits the ITO onto the substrate, the first temperature being sufficient to form crystalline ITO on the substrate; and

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

12. The apparatus of claim 11, wherein the deposition chamber is a physical vapor deposition chamber.

13. 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 a wavelength of the EM radiation, an intensity of the EM radiation, and an incident angle of the EM radiation.

24. The apparatus of claim 13, wherein the incident angle of the EM radiation is within a range between and including a grazing angle and a 45 degree angle.

14. 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 is 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.