Systems and methods for monitoring material properties using microwave energy

• US 5,648,038 A
• Filed: 09/20/1995
• Issued: 07/15/1997
• Est. Priority Date: 09/20/1995
• Status: Expired due to Term

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Lambda Technologies, Inc
• Inventors: Hampton, Michael L., Fathi, Zakaryae, Garard, Richard S., Wei, Jianghua
• Primary Examiner(s): THURLOW, JEFFERY
• Application Number:
  US08/531,045
• Time in Patent Office: 664 Days
• Field of Search: 264/406, 264/408, 264/490, 264/489, 264/40.1, 425/174.4, 425/135, 425/143, 324/636, 324/639, 324/634
• US Class Current: 264/406
• CPC Class Codes: G01N 22/00 Investigating or analysing materials by the use of microwaves or radio waves, i.e. electromagnetic waves with a wavelength of one millimetre or more G01N3/00 - G01N17/00, G01N24/00 take precedence
• CPC Class Codes: H05B 6/705 using microwave tuning

Abstract

Systems and methods for monitoring workpiece and workpiece material characteristics using microwave energy are disclosed. A system includes a chamber, including means for generating variable frequency microwave energy; means for positioning a workpiece within the chamber; means for subjecting the workpiece to a plurality of different microwave frequencies; and means for monitoring characteristics of the workpiece. One or more characteristics of a workpiece, or workpiece material, may be monitored by positioning the workpiece within a chamber having means for generating variable frequency microwave energy; subjecting the workpiece to microwave irradiation at a plurality of frequencies; detecting power reflection for each one of the plurality of microwave frequencies to provide power reflection data; and comparing the power reflection data to a predetermined set of power reflection data. The result of signature analysis can be coupled with a product process controller to achieve a real-time feedback control on monitoring and adjusting of process parameters.

Claims

1. A method for monitoring a characteristic of a workpiece, said method comprising the steps of:

positioning the workpiece within a chamber having means for generating variable frequency microwave energy;

sweeping the workpiece with microwave irradiation at a plurality of frequencies;

detecting power reflection for each one of the plurality of microwave frequencies to provide power reflection data; and

comparing the power reflection data to a predetermined set of power reflection data.

2. A method according to claim 1, further comprising the step of storing the power reflection data.

3. A method according to claim 1, further comprising the step of generating a signature curve for the workpiece by plotting the power reflection data as a function of microwave frequency.

4. A method according to claim 1, wherein a characteristic of a plurality of workpieces are monitored.

5. A method according to claim 4, further comprising the step of identifying a workpiece having power reflection data that does not fall within an acceptable range of power reflection data.

6. A method according to claim 4, wherein a plurality of different characteristics of a plurality of workpieces are monitored by comparing the power reflection data to a plurality of predetermined sets of power reflection data.

7. A method for processing a workpiece with microwave energy, said method comprising the steps of:

positioning the workpiece within a chamber having means for generating variable frequency microwave energy;

processing the workpiece by sweeping the workpiece with at least one frequency of microwave irradiation; and

monitoring a first characteristic of the workpiece during said step of processing.

8. A method according to claim 7, wherein said monitoring step comprises:

detecting power reflection for each one of a plurality of microwave frequencies to provide power reflection data; and

comparing the power reflection data to a first predetermined set of power reflection data.

9. A method according to claim 8, further comprising the step of storing the power reflection data.

10. A method according to claim 7, further comprising the step of generating a signature curve for the workpiece by plotting the power reflection data as a function of microwave frequency.

11. A method according to claim 7, further comprising the step of monitoring a second characteristic of the workpiece by comparing the power reflection data to a second predetermined set of power reflection data.

12. A method according to claim 8, further comprising the step of identifying a workpiece having power reflection data that does not fall within an acceptable range of power reflection data.

13. A method according to claim 12, wherein said identifying step is performed during said processing step.

14. A method for monitoring the degree of cure of a resin, said method comprising the steps of:

positioning the resin within a chamber having means for generating variable frequency microwave energy;

sweeping the resin with microwave irradiation at a plurality of frequencies;

detecting power reflection for each one of the plurality of microwave frequencies to provide power reflection data; and

comparing the power reflection data to a predetermined set of power reflection data.

15. A method according to claim 14, further comprising the step of storing the power reflection data.

16. A method according to claim 14, further comprising the step of generating a signature curve for the resin by plotting the power reflection data as a function of microwave frequency.

17. A system for microwave processing, said system comprising:

a chamber including means for generating variable frequency microwave energy;

means for positioning a workpiece within said chamber;

means for sweeping the workpiece with a plurality of different microwave frequencies; and

means for monitoring a first characteristic of the workpiece.

18. A system according to claim 17, wherein said means for monitoring a first characteristic of the workpiece comprises:

means for detecting power reflection for each one of the plurality of microwave frequencies to provide power reflection data; and

means for comparing the power reflection data to a first predetermined set of power reflection data.

19. A system according to claim 18, further comprising means for storing the power reflection data.

20. A system according to claim 18, further comprising means for generating a signature curve for the workpiece by plotting the power reflection data as a function of microwave frequency.

21. A system according to claim 17, comprising means for processing a plurality of workpieces simultaneously.

22. A system according to claim 17, further comprising means for identifying a workpiece having power reflection data that does not fall within an acceptable range of power reflection data.

23. A system according to claim 22, further comprising means for identifying a workpiece having power reflection data that does not fall within an acceptable range of power reflection data during microwave processing of the workpiece.

24. A system according to claim 17, wherein the workpiece comprises a resin and the first characteristic is the degree of cure of the resin.

25. A system according to claim 17, further comprising means for providing real-time feedback control.