Method and resulting device for fabricating electret materials on bulk substrates

• US 20040016120A1
• Filed: 06/04/2003
• Published: 01/29/2004
• Est. Priority Date: 06/07/2002
• Status: Abandoned Application

• Current Assignee: California Institute of Technology
• Original Assignee: California Institute of Technology
• Inventors: Boland, Justin, Tai, Yu-Chong
• Application Number:
  US10/455,226
• Publication Number:
  US 20040016120A1
• Time in Patent Office: Days
• US Class Current: 29/886
• CPC Class Codes: H02N 1/08 with conductive charge carrier, i.e. capacitor machines
• CPC Class Codes: Y10T 29/49226 Electret making

Abstract

An electret device. The device has a thickness of substrate material having a contact region. An electrically floating conducting region is formed overlying the thickness of substrate material. The floating conducting region is free from physical contact with the contact region. A protective layer is formed overlying the floating conductive layer. The protective layer has a surface region and seals the floating conducting region. The thickness of substrate material, floating conducting region, and protective layer form a sandwiched structure having a charge density of at least 1×10−4 Coulombs/m2 and a peak to peak charge uniformity of 5% and less.

Claims

1. A method of fabricating an electret device, the method comprising:

providing a thickness of substrate material having a contact region;

forming an electrically floating conducting region formed overlying the thickness of substrate material, the floating conducting region being free from physical contact with the contact region;

forming a protective layer formed overlying the floating conductive layer, the protective layer having a surface region, the protective layer sealing the floating conducting region;

whereupon the thickness of substrate material, floating conducting region, and protective layer form a sandwiched structure having an initial charge density of at least 1×

10<sup>−

4</sup> Coulombs/m² and a peak to peak charge uniformity of 5% and less.

2. The method of claim 1 wherein the forming of the floating conducting region comprises patterning using at least a micromachining process.

3. The method of claim 1 wherein the thickness of substrate material is a Teflon material having a thickness of about 100 microns and less;

wherein the floating conducting region comprises an aluminum bearing material having a thickness of 5000 Angstroms and less.

4. The method of claim 1 wherein the thickness of substrate material comprises Teflon.

5. The method of claim 1 wherein the floating conducting region comprises an aluminum bearing material or an aluminum alloy bearing material.

6. The method of claim 1 wherein the protective layer is Teflon.

7. The method of claim 1 wherein the floating conducting region is a single layer or multiple layers.

8. The method of claim 1 wherein the protective layer is sputtered oxide, a plasma deposited fluoro-polymer, SOG (“

Spin-On-Glass”

).

9. The method of claim 1 wherein the protective layer has a resistivity of greater than a predetermined amount.

10. The method of claim 1 wherein the floating conductive layer has a conductivity is at least a predetermined amount.

11. The method of claim 1 wherein the conductive layer has a resistivity value less than a resistivity value of the protective layer.

12. The method of claim 1 wherein the charge density is provided by implantation of a plurality of electrons.

13. The method of claim 1 wherein the plurality of electrons are provided by a process selected from corona discharge, electron beam injection ion-beam implantation, contact electrification, thermal charging, radiative and photoelectret processes, and triboelectric charging, and e-beam.

14. The method of claim 1 wherein the substrate is provided via spinning liquid Teflon.

15. The method of claim 1 wherein the substrate is provided via compression molding.

16. The method of claim 1 substrate is selected from chemical vapor deposition, plasma enhanced vapor deposition, electrospray, and aerosol deposition.

17. The method of claim 1 wherein the substrate is provided on a mounting substrate to hold the substrate in place.

18. The method of claim 17 wherein the mounting substrate comprises an overlying metal layer, the metal layer coupled to the substrate.

19. The method of claim 1 wherein the substrate is made using damascene process.

20. The method of claim 1 wherein A method of fabricating an electret device, the method comprising:

providing a thickness of substrate material having a contact region;

forming an electrically floating conducting region formed overlying the thickness of substrate material, the floating conducting region being free from physical contact with the contact region;

forming a protective layer formed overlying the floating conductive layer, the protective layer having a surface region, the protective layer sealing the floating conducting region;

whereupon the thickness of substrate material, floating conducting region, and protective layer form a sandwiched structure having an initial charge density of at least 1×

10<sup>−

4</sup> Coulombs/m² and a peak to peak charge uniformity of 5% and less;

whereupon the floating conductive layer interacts with charge charged particles to facilitate the a uniform spatial distribution of charge along the electrically floating conducting region.

21. The method of claim 20 wherein the charged particles are is provided via implantation of a plurality of particles.

22. An electret device comprising:

a thickness of substrate material having a contact region;

a floating conducting region formed overlying the thickness of substrate material, the floating conducting region being free from physical contact with the contact region;

a protective layer formed overlying the floating conductive layer, the protective layer having a surface region, the surface region being free from physical contact with the floating conducting region;

whereupon the thickness of substrate material, floating conducting region, and protective layer form a sandwiched structure having a charge density of at least 1×

10−

4 Coulombs/m² and a peak to peak charge uniformity of 5% and less.

23. The device of claim 22 wherein the floating conducting region is patterned using at least a micromachining process.

24. The device of claim 22 wherein the thickness of substrate material is a Teflon material having a thickness of about 40 microns and less;

wherein the floating conducting region comprises an aluminum bearing material having a thickness of 5000 Angstroms and less.

25. The device of claim 22 wherein the thickness of substrate material comprises Teflon.

26. The device of claim 22 wherein the floating conducting region comprises an aluminum bearing material or an aluminum alloy bearing material.

27. The device of claim 22 wherein the protective layer is Teflon.

28. The device of claim 22 wherein the floating conducting region is a single layer or multiple layers.

29. The device of claim 22 wherein the protective layer is sputtered oxide, a plasma deposited fluoro-polymer, or SOG.

30. The device of claim 22 wherein the protective layer has a resistivity of greater than a predetermined amount.

31. The device of claim 22 wherein the floating conductive layer has a conductivity is at least a predetermined amount.

32. The device of claim 22 wherein the conductive layer has a resistivity value less than a resistivity value of the protective layer.

33. The device of claim 22 wherein the charge density being measured via a voltage potential.

34. The device of claim 22 wherein the charge density is provided by implantation of a plurality of electrons.

35. The device of claim 22 wherein the plurality of electrons are provided by a e-beam.

36. The device of claim 22 wherein the substrate is provided via spinning liquid Teflon.

37. The device of claim 22 wherein the substrate is provided via compression molding.

38. The device of claim 22 substrate is selected from silicon, glass, and plastic.

39. The device of claim 22 wherein the substrate is provided on a mounting substrate to hold the substrate in place.

40. The device of claim 39 wherein the mounting substrate comprises an overlying metal layer, the metal layer coupled to the substrate.

41. The device of claim 22 wherein the substrate is made using damascene process.

42. The device of claim 22 wherein floating conductive layer interacts with charge to facilitate the uniform distribution of charge.

43. The device of claim 42 wherein the charge is provided via implantation of a plurality of particles.