Systems and methods for thin film thermal diagnostics with scanning thermal microstructures

• US 20060051884A1
• Filed: 09/01/2005
• Published: 03/09/2006
• Est. Priority Date: 09/03/2004
• Status: Active Grant

• Current Assignee: PicoCal, Inc.
• Original Assignee: PicoCal, Inc.
• Inventors: Gianchandani, Yogesh B., McNamara, Shamus
• Granted Patent: US 7,262,066 B2
• Time in Patent Office: Days
• US Class Current: 438/14
• CPC Class Codes: G01N 25/18 by investigating thermal conductivity by calorimetry G01N25/20; by measuring change of resistance of an electrically-heated body G01N27/18
• CPC Class Codes: G01Q 60/58 SThM [Scanning Thermal Microscopy] or apparatus therefor, e.g. SThM probes
• CPC Class Codes: H01L 22/12 for structural parameters, e.g. thickness, line width, refractive index, temperature, warp, bond strength, defects, optical inspection, electrical measurement of structural dimensions, metallurgic measurement of diffusions electrical measurement of diffusions H01L22/14
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

Systems and methods are described for identifying characteristics and defects in material such as semiconductors. Methods include scanning a thermal probe in the vicinity of a semiconductor sample, applying stimuli to the thermal probe, and monitoring the interaction of the thermal probe and the semiconductor. The stimulus can be applied by a variety of methods, including Joule heating of a resistor in the proximity of the probe tip, or optically heating a tip of the thermal probe using a laser. Applications of the invention include identification of voids in metallic layers in semiconductors; mapping dopant concentration in semiconductors; measuring thickness of a sample material; mapping thermal hot spots and other characteristics of a sample material.

Claims

1. A method of measuring properties of a film sample, comprising:

scanning across the sample one or more microstructures, the one or more microstructures containing at least one thermal probe and at least one of a thermal sensor and a thermal stimulator;

applying a stimulus to the one or more microstructures wherein the stimulus includes a temporally varying waveform;

detecting a response of the one or more microstructures from an interaction of the sample and the applied stimulus;

correlating a position of the one or more microstructures with the response of the one or more microstructures.

2. The method of claim 1, wherein the temporally varying waveform includes a periodic component that has a frequency greater than 10⁻

5 Hz.

3. The method of claim 1, further including:

storing the response of the one or more microstructures.

4. The method of claim 1, further including measuring a phase difference between the applied stimulus and the detected response.

5. The method of claim 4, further including identifying a maxima and a minima of the phase difference.

6. The method of claim 1, further including measuring an amplitude of the detected response.

7. The method of claim 1, wherein the response of the one or more microstructures includes an increase in temperature occurring in a time period shorter than a thermal time constant of the one or more thermal probes.

8. The method of claim 1, further including maintaining the one or more microstructures at a substantially constant temperature.

9. The method of claim 1, wherein the stimulus is applied for a duration of time substantially shorter than a thermal time constant of the one or more microstructures.

10. The method of claim 1, wherein the one or more microstructures includes a microbolometer in proximity to a tip of the one or more microstructures.

11. The method of claim 1, wherein the one or more microstructures includes a thermocouple in proximity to a tip of the one or more microstructures.

12. The method of claim 1, further including applying a light source in proximity to a tip of the one or more microstructures.

13. The method of claim 1, further including actuating the one or more microstructures with a piezoelectric drive.

14. The method of claim 13, wherein the one or more microstructures is actuated with one of a motor actuator and linear actuator with a travel distance of 1 cm to 30 cm and a position accuracy of 1 micrometer to 5 nanometer.

15. The method of claim 1, wherein the stimulus heats the sample through a tip of the one or more thermal probes.

16. The method of claim 1, wherein the stimulus generates a thermal evanescent wave in the sample.

17. The method of claim 1, wherein the stimulus generates a thermal-acoustic wave in the sample.

18. The method of claim 1, wherein the response of the one or more microstructures is used to identify defects within said sample.

19. The method of claim 1, wherein the sample is an integrated circuit.

20. The method of claim 19, wherein the response of the one or more microstructures is used to identify voids in the metal layers of the integrated circuit.

21. The method of claim 19, wherein the response of the one or more microstructures is used to identify a partially or fully blocked contact between metal layers on the integrated circuit.

22. The method of claim 19, wherein the response of the one or more microstructures identifies crystalline damage due to ion implantation in the integrated circuit.

23. The method of claim 1, wherein the sample is a semiconductor, and the response of the one or more microstructures identifies crystalline defects the in semiconductor.

24. The method of claim 1, further comprising:

mapping a concentration of dopant atoms in the sample at a sub-micron resolution.

25. The method of claim 1, further comprising:

measuring one or more grain boundaries in the sample, wherein the sample includes polycrystalline materials.

26. The method of claim 1, wherein the response of the one or more microstructures identifies cracks within a layer of the sample.

27. The method of claim 1, wherein the response of the one or more thermal probes identifies a presence of a boundary between two dissimilar materials contained in the sample, and the response further identifies one or more characteristics of the boundary, the one or more characteristics selected from the group consisting of:

a strength of the boundary, a uniformity of the boundary, and a uniformity of a bond between the dissimilar materials.

28. The method of claim 27, wherein the stimulus includes an evanescent wave and the response of the one or more thermal probes includes thermal wave interference from the two dissimilar materials.

29. The method of claim 1, wherein the response of the one or more microstructures identifies a thickness of the sample, wherein the sample comprises a thin film.

30. The method of claim 29, where the response of the one or more microstructures is used to determine the thickness of the barrier films deposited on an integrated circuit prior to a metal electroplating step on an integrated circuit.

31. The method of claim 29, where the response of the one or more microstructures is used to identify the thickness of metal on an integrated circuit.

32. The method of claim 29, where the response of the one or more microstructures is used to identify the thickness of dielectric films on an integrated circuit.

33. The method of claim 1, where the response of the one or more microstructures is used to determine the localized temperature of the sample.