Fabrication of solid state electronic devices using fluorescent imaging of surface temperature profiles

• US 4,455,741 A
• Filed: 10/15/1982
• Issued: 06/26/1984
• Est. Priority Date: 02/11/1982
• Status: Expired due to Term

• Current Assignee: Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Original Assignee: AT&T, Inc.
• Inventors: Kolodner, Paul R.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US06/434,635
• Time in Patent Office: 620 Days
• Field of Search: 29/574, 250/458.1, 250/459.1, 374/159, 374/161
• US Class Current: 438/16
• CPC Class Codes: G01K 11/20 using thermoluminescent materials G01K11/32 takes precedence
• CPC Class Codes: G01N 25/72 Investigating presence of flaws

Abstract

Solid state electronic devices are optically monitored during fabrication to detect hot spots which are indicative of faulty operation. The surface temperatures of such a device are measured by applying a fluorescent material to the device, and subsequently monitoring the temperature dependent fluorescence of the material, which is reflective of the temperature of the underlying device. Devices are accepted, rejected, or further processed in response to the monitored fluorescence.

Claims

1. A method for fabricating a solid state electronic device, comprising the steps of:

forming a layer of fluorescent material on a surface of a partially or fully completed solid state electronic device, the fluorescence of said material varying as the temperature of the underlying device varies;

exposing said material to energy which causes said material to fluoresce;

monitoring the fluorescence of said material while the solid state electronic device is contacted with a voltage and/or current source; and

accepting, rejecting, or further processing said device in response to the monitored fluorescence.

2. The method of claim 1 wherein said layer of material is less than 10 microns thick.

3. The method of claim 2 wherein said layer of material is less than 5 microns thick.

4. The method of claim 3 wherein said layer of material is less than 1 micron thick.

5. The method of claim 1 wherein the fluorescence of said material is detectably responsive to temperature changes less than 10 degrees Celsius.

6. The method of claim 5 wherein the fluorescence of said material is detectably responsive to temperature changes less than 1 degree Celsius.

7. The method of claim 6 wherein the fluorescence of said material is detectably responsive to temperature changes less than a tenth of a degree Celsius.

8. The method of claim 7 wherein the fluorescence of said material is detectably responsive to temperature changes less than a hundredth of a degree Celsius.

9. The method of claim 1 wherein the spatial resolution of the thermal profile associated with the monitored fluorescence is less than 50 microns.

10. The method of claim 9 wherein the spatial resolution of the thermal profile associated with the monitored fluorescence is less than 2 microns.

11. The method of claim 1 wherein the energy which causes the material to fluoresce is ultraviolet light in the spectral range of 300 to 400 nanometers.

12. The method of claim 1 wherein the monitored fluorescence is normalized to the fluorescence monitored when the device is not contacted with a voltage and/or current source.

13. The method of claim 1 wherein the material layer comprises Europium Thenoyltrifluoroacetonate (EuTTA) distributed in PMMA.

14. The method of claim 12 wherein the material layer comprises Europium Thenoyltrifluoroacetonate (EuTTA) distributed in dPMMA.

15. The method of claim 14 wherein said layer includes about 0.5 to about 40 percent by weight of Europium Thenoyltrifluoroacetonate (EuTTA).

16. The method of claim 15 wherein the fluorescence intensity of the material layer varies with temperature as approximately a straight line with a slope of approximately -0.05/degree Celsius.

17. The method of claim 16 wherein said layer is illuminated with approximately 700 microwatts per centimeter squared of UV radiation in the wavelength range from 345 to 380 nanometers.

18. The method of claim 1 wherein said fluorescence is monitored using a CCD array.

19. The method of claim 10 wherein said fluorescence is monitored using a CCD array.

20. The method of claim 15 wherein said fluorescence is monitored using a CCD array.

21. The method of claim 20 wherein a thermal picture of substantially the entire device is imaged by a CCD array.

22. The method of claim 1 wherein said material layer comprises EuFOD distributed in a polymer.

23. The method of claim 22 wherein said layer includes about 2 to about 50 percent by weight of the EuFOD.

24. The method of claim 1, further comprising the step of producing a thermal transient in said device by delivering power, or increasing the delivery of power, to said device.

25. The method of claim 24 wherein said exposing step occurs substantially simultaneously with the onset of said thermal transient, and wherein the resulting fluorescence of said material is detected during said monitoring step.

26. The method of claim 24, wherein said exposing step occurs over a period of time which includes the duration of said thermal transient, and said monitoring step includes the step of gating a detector which detects the fluorescence of said material, substantially simultaneously with the onset of said thermal transient.

27. The method of claim 25 wherein said layer of fluorescent material has a fluorescence lifetime, τ

, which is smaller than t_x, the time required for heat to diffuse a preselected distance across the surface of said device, and wherein said exposing step occurs over a period of time less than t_x.

28. The method of claim 26 wherein said layer of fluorescent material has a fluorescence lifetime, τ

, which is smaller than t_x, the time required for heat to diffuse a preselected distance across the surface of said device, and wherein said detector is gated for a period of time less than t_x.

29. The method of claim 1 wherein said layer of fluorescent material has a fluorescence lifetime which is less than 10 nanoseconds.

31. The method of claim 29 wherein said material comprises bianthrone.

32. The method of claim 29 wherein said material comprises dimethylaminoazobenzene.

33. The method of claim 29 wherein said material comprises 9-methylanthracene.

34. The method of claim 1 wherein said device is an integrated circuit device.

35. The method of claim 1 wherein said device is a laser diode.

36. The method of claim 1 wherein said device is a Josephson junction device.

30. The method of clainm 29 wherein said material comprises Rhodamine B distributed in polyethyleneimine.