Process control monitors for interferometric modulators

• US 20060066871A1
• Filed: 11/17/2005
• Published: 03/30/2006
• Est. Priority Date: 09/27/2004
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: IDC, LLC
• Inventors: Cummings, William, Gally, Brian
• Granted Patent: US 7,259,865 B2
• Time in Patent Office: Days
• US Class Current: 356/503
• CPC Class Codes: B81B 2201/042 Micromirrors, not used as optical switches
• CPC Class Codes: B81C 99/004 during manufacturing
• CPC Class Codes: G01N 21/55 Specular reflectivity
• CPC Class Codes: G01N 21/9501 Semiconductor wafers manufacturing processes per se of semiconductor devices implementing a measuring step H01L22/10
• CPC Class Codes: G02B 26/001 based on interference in an adjustable optical cavity interference filters G02B5/28; devices or arrangements using multiple reflections in spectrometry or monochromators G01J3/26

Abstract

Process control monitors are disclosed that are produced using at least some of the same process steps used to manufacture a MEMS device. Analysis of the process control monitors can provide information regarding properties of the MEMS device and components or sub-components in the device. This information can be used to identify errors in processing or to optimize the MEMS device. In some embodiments, analysis of the process control monitors may utilize optical measurements.

Claims

1. A method of monitoring deposition of material deposited during manufacturing of a micro-electro-mechanical system (MEMS), comprising:

forming a process control monitor that consists of at least three layers of material deposited during the manufacturing, wherein the at least three layers of material is less than the number of layers deposited during manufacturing of the MEMS, wherein the at least three layers of material form an etalon; and

detecting light reflected from the etalon, whereby information regarding properties of the at least three layers is obtained.

2. The method of claim 1, wherein forming the process control monitor comprises exposing the process control monitor to the same material deposition and patterning steps as used during the manufacturing.

3. The method of claim 1, further comprising determining an index of refraction of at least one of the materials from the detected light.

4. The method of claim 1, further comprising determining reflectivity of at least one of the materials from the detected light.

5. The method of claim 1, further comprising determining transmittance of at least one of the materials from the detected light.

6. The method of claim 1, further comprising determining the thickness of at least one of the materials from the detected light.

7. The method of claim 1, further comprising determining the depth of the etalon from the detected light.

8. The method of claim 1, wherein the detecting comprises measuring the reflected light with a photodetector.

9. The method of claim 1, wherein the detecting comprises measuring a spectrum of the reflected light with a spectrometer.

10. The method of claim 9, further comprising fitting the spectrum with a model of light reflected from an etalon.

11. The method of claim 1, wherein the detecting comprises measuring the reflected light with a colorimeter.

12. The method of claim 1, wherein detecting the reflected light comprises detecting reflectance from a side of the process control monitor where the at least three layers of material are deposited during formation of the process control monitor.

13. The method of claim 1, wherein detecting the reflected light comprises detecting reflectance from a side of the process control monitor opposite the side where the at least three layers of material are deposited during formation of the process control monitor.

14. A wafer, comprising:

a plurality of interferometric modulators adapted for use in a display; and

a non-modulating interferometer.

15. The wafer of claim 14, wherein the non-modulating interferometer comprises at least one layer of material that is substantially the same as a layer of material in the interferometric modulators.

16. The wafer of claim 14, wherein the non-modulating interferometer comprises at least three layers of material that together form an etalon.

17. The wafer of claim 16, wherein no substantial air gap exists between reflecting surfaces in the etalon.

18. A method of monitoring deposition of material deposited during manufacturing of a micro-electro-mechanical system (MEMS), comprising:

forming a process control monitor comprising one or more layers of material deposited during the manufacturing, wherein the number of layers of material in the process control monitor is less than the number of layers deposited during manufacturing of the MEMS; and

detecting the reflectance of the process control monitor, whereby the reflectance provides information regarding properties of the layers in the process control monitor.

19. The method of claim 18, wherein forming the process control monitor comprises applying an identical sequence of material deposition and patterning steps as used in the manufacturing of the MEMS.

20. The method of claim 18, wherein the final layer of material in the process control monitor is substantially reflective.

21. The method of claim 18, further comprising determining the reflectance of one of the layers in the process control monitor.

22. The method of claim 18, further comprising determining the transmittance of one of the layers in the process control monitor.

23. The method of claim 18, further comprising determining the thickness of one of the layers in the process control monitor.

24. The method of claim 18, wherein the detecting comprises measuring a spectrum of light reflected from the process control monitor.

25. The method of claim 18, wherein detecting the reflectance comprises detecting reflectance from a side of the process control monitor where the one or more layers of material are deposited during formation of the process control monitor.

26. The method of claim 18, wherein detecting the reflectance comprises detecting reflectance from a side of the process control monitor opposite the side where the one or more layers of material are deposited during formation of the process control monitor.

27. A wafer, comprising:

a plurality of interferometric modulators adapted for use in a display, the interferometric modulators comprising a plurality of material layers; and

a process control monitor comprising one or more of the material layers, wherein the process control monitor comprises less than all of the plurality of material layers.

28. The wafer of claim 27, wherein the process control monitor comprises an etalon.

29. The wafer of claim 27, wherein the final layer in the process control monitor is substantially reflective.

30. The wafer of claim 29, wherein layers other than the final layer in the process control monitor are substantially transparent.

31. A method of manufacturing a combined micro-electro-mechanical system (MEMS) and process control monitor structure, comprising:

forming a MEMS structure, wherein forming the MEMS structure includes one or more material deposition and patterning steps; and

simultaneously forming a process control monitor, wherein forming the process control monitor includes said one or more material deposition and patterning steps, wherein the process control monitor comprises less than all components present in the MEMS structure.

32. A wafer produced by a process, comprising:

depositing and patterning a series of material layers on a substrate to form a MEMS structure; and

simultaneously depositing and patterning a series of material layers on the substrate to form a process control monitor, wherein the process control monitor comprises less than all components present in the MEMS structure.