Evaporation method and apparatus using infrared guiding heater

• US 20060153986A1
• Filed: 01/07/2005
• Published: 07/13/2006
• Est. Priority Date: 01/07/2005
• Status: Active Grant

• Current Assignee: Universal Display Corporation
• Original Assignee: Universal Display Corporation
• Inventors: Yamamoto, Hitoshi
• Granted Patent: US 7,431,807 B2
• Time in Patent Office: Days
• US Class Current: 427/255.600
• CPC Class Codes: C23C 14/12 Organic material
• CPC Class Codes: C23C 14/228 Gas flow assisted PVD deposition
• CPC Class Codes: C23C 14/28 by wave energy or particle radiation C23C14/32 - C23C14/48 take precedence
• CPC Class Codes: C23C 14/52 Means for observation of the coating process
• CPC Class Codes: C23C 14/54 Controlling or regulating the coating process
• CPC Class Codes: H10K 71/16 using physical vapour deposition [PVD], e.g. vacuum deposition or sputtering

Abstract

A method and apparatus for evaporating a solid organic material by sublimation using an infrared guiding heater which minimizes temperature gradients in the bulk of the organic target. The bulk is heated to a temperature below the sublimation temperature of the target. A localized area of the target is sublimated by the infrared guiding heater while regulating the temperature of the bulk. The vapor is then deposited over, and condensed on, a substrate to form a solid organic layer.

Claims

1. A method, comprising:

(a) providing a target consisting of a solid organic material;

(b) heating a bulk of the solid organic material to a first temperature using a first heat source, the first temperature being below a sublimation temperature of the solid organic material;

(c) sublimating a localized portion of the target by selectively heating the localized portion to a second temperature at or above the sublimation temperature using a second heat source;

(d) transporting the sublimated organic material from the target to a substrate; and

(e) depositing the sublimated organic material over the substrate to form a layer comprising the solid organic material.

2. The method of claim 1, wherein the first temperature is at least 50 degrees Celsius less than the thermal decomposition temperature of the solid organic material.

3. The method of claim 1, wherein the first temperature is 10 to 50 degrees Celsius less than the sublimation temperature.

4. The method of claim 1, wherein the bulk is heated to the first temperature prior to sublimating the localized portion, and wherein the bulk is maintained at the first temperature during sublimation.

5. The method of claim 1, wherein the second temperature is no more than 10 degrees Celsius above the sublimation temperature.

6. The method of claim 1, wherein sublimating the localized portion comprises:

(c1) selectively targeting infrared energy onto the localized portion to selectively heat said localized portion to the second temperature.

7. The method of claim 6, further comprising:

(f) scanning the infrared energy across a surface of the target.

8. The method of claim 6, wherein sublimating the localized portion further comprises:

(c2) focusing the infrared energy to control a cross-sectional area of the infrared energy at a surface of the target.

9. The method of claim 1, wherein a surface area of the localized portion is equivalent to less than 10% of an initial exposed surface area of the target available for sublimation, prior to an initiation of sublimation.

10. The method of claim 1, further comprising:

spectroscopically detecting impurities in the sublimated organic material indicative of decomposition; and

responsive to detecting impurities in the sublimated organic material by performing at least one of;

lowering said first temperature of the bulk;

adjusting a cross-sectional area of targeted infrared energy applied to the localized portion to sublimate the solid organic material;

adjusting an intensity of targeted infrared energy applied to the localized portion to sublimate the solid organic material;

adjusting a duration of an infrared pulse applied to the localized portion to sublimate the solid organic material; and

changing a targeting of infrared energy applied to the target to sublimate the solid organic material to avoid an area of a surface of the target from which the impurities originated.

11. The method of claim 1, further comprising:

monitoring a sublimation rate of the solid organic material; and

responsive to a change in the sublimation rate, performing at least one of;

lowering said first temperature of the bulk;

adjusting a cross-sectional area of targeted infrared energy applied to the localized portion to sublimate the solid organic material;

adjusting an intensity of targeted infrared energy applied to the localized portion to sublimate the solid organic material;

adjusting a duration of an infrared pulse applied to the localized portion to sublimate the solid organic material; and

changing a targeting of infrared energy applied to the target to sublimate the solid organic material to avoid an area of a surface of the target from which the impurities originated.

12. The method of claim 1, further comprising:

measuring temperature at a surface of the solid organic material by radiometry; and

responsive to the measured temperature, performing at least one of;

lowering said first temperature of the bulk;

adjusting a cross-sectional area of targeted infrared energy applied to the localized portion to sublimate the solid organic material;

adjusting an intensity of targeted infrared energy applied to the localized portion to sublimate the solid organic material;

adjusting a duration of an infrared pulse applied to the localized portion to sublimate the solid organic material; and

changing a targeting of infrared energy applied to the target to sublimate the solid organic material to avoid an area of the surface of the target from which the impurities originated.

13. An apparatus, comprising:

a deposition chamber adapted to have a substrate disposed therein;

a target site adapted to receive a target, such that material evaporated from the target deposits on the substrate;

a bulk heater adapted to heat a bulk of the target at the target site; and

an infrared guiding heater comprising;

an infrared source; and

optical components adapted to direct energy from the infrared source onto a surface of the target and thereby evaporate the material.

14. The apparatus of claim 13, the optical components comprising:

a focusing lens to focus the energy from the infrared source and control a cross-sectional area of the energy at the surface of the target.

15. The apparatus of claim 14, the optical components further comprising:

a diffractive optic adapted to reshape an intensity profile of the energy, positioned in an optical path of the energy between the infrared source and the focusing lens.

16. The apparatus of claim 13, the optical components comprising:

a collimator.

17. The apparatus of claim 13, the optical components comprising:

a targeting element in an optical path of the energy between the infrared source and the target, adapted to alter an optical path of the energy and thereby select a location where the energy strikes the surface of the target; and

the apparatus further comprising at least one electromechanical actuator to displace the targeting element to alter the optical path,

wherein the targeting element is selected from the group consisting of a mirror and a prism.

18. The apparatus of claim 13, the deposition chamber further comprising an in-situ crystal monitor to measure a thickness of a film to be formed on the substrate.

19. The apparatus of claim 13, further comprising:

a radiation detector positioned to receive energy radiated from the target; and

a signal processor to calculate a surface temperature of the target based upon the radiated energy received by the radiation detector.

20. The apparatus of claim 13, further comprising:

a photodetector adapted to measure an absorption spectra of the material evaporated from the target; and

a signal processor to detect impurities in the material evaporated from the target indicative of decomposition based upon the absorption spectra measured by the photodetector.

21. The apparatus of claim 13, wherein the bulk heater is selected from the group consisting of an infrared heater, a contact heater, a radio frequency heater, and an electromagnetic dielectric heater, and

wherein the infrared source is selected from the group consisting of a carbon heater, a halogen lamp heater, a shortwave-infrared heater, a xenon lamp, and a laser.