Transitioned film growth for conductive semiconductor materials

• US 8,765,514 B1
• Filed: 11/12/2010
• Issued: 07/01/2014
• Est. Priority Date: 11/12/2010
• Status: Active Grant

• Current Assignee: DRS Network & Imaging Systems, LLC (Leonardo S.p.A.)
• Original Assignee: L-3 Communications Corporation (L3Harris Technologies, Inc.)
• Inventors: Syllaios, Athanasios J., Taylor, Michael F., Ajmera, Sameer K.
• Primary Examiner(s): Nikmanesh, Seahvosh
• Assistant Examiner(s): Seven, Evren
• Application Number:
  US12/945,011
• Publication Number:
  US 20140159032A1
• Time in Patent Office: 1,327 Days
• Field of Search: None
• US Class Current: 438/57
• CPC Class Codes: G01J 5/20 using resistors, thermistors or semiconductors sensitive to radiation, e.g. photoconductive devices
• CPC Class Codes: H01L 21/02529 Silicon carbide
• CPC Class Codes: H01L 21/02532 Silicon, silicon germanium, germanium
• CPC Class Codes: H01L 21/02573 Conductivity type
• CPC Class Codes: H01L 21/02592 amorphous
• CPC Class Codes: H01L 27/14618 Containers
• CPC Class Codes: H01L 27/14649 Infrared imagers
• 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
• CPC Class Codes: H01L 31/028 including, apart from doping material or other impurities, only elements of Group IV of the Periodic Table
• CPC Class Codes: H01L 31/0336 in different semiconductor regions, e.g. Cu2X/CdX hetero- junctions, X being an element of Group VI of the Periodic Table
• CPC Class Codes: H01L 31/0376 including amorphous semiconductors H01L31/0392 takes precedence
• CPC Class Codes: H01L 31/20 such devices or parts thereof comprising amorphous semiconductor materials

Abstract

A center region of conductive material/s may be disposed or “sandwiched” between transition regions of relatively lower conductivity materials to provide substantially low defect density interfaces for the sandwiched material. The center region and surrounding transition regions may in turn be disposed or sandwiched between dielectric insulative material to form a sandwiched and transitioned device structure. The center region of such a sandwiched structure may be implemented, for example, as a device layer such as conductive microbolometer layer for a microbolometer detector structure.

Claims

1. An infrared detector element comprising:

a substrate; and

an infrared detector membrane disposed in spaced relationship above the substrate;

where the infrared detector membrane comprises;

a first dielectric insulative layer,

a first transition region disposed on the first dielectric insulative layer,

a conductive center region disposed on the first transition region,

a second transition region disposed on the conductive center region, and

a second dielectric insulative layer disposed on the second transition region;

where at least a portion of each of the first and second transition regions has a lower conductivity than the conductive center region and a greater conductivity than the first and second dielectric insulative layers.

2. The infrared detector element of claim 1, where a material matrix of the conductive center region comprises at least one of an amorphous silicon matrix, an amorphous silicon germanium matrix;

an amorphous silicon fluorine matrix;

an amorphous silicon carbon matrix, a vanadium oxide matrix, a vanadium oxide amorphous silicon matrix, a titanium oxide matrix, a germanium matrix, a silicon germanium oxide matrix, or a nickel manganite spinel matrix.

3. The infrared detector element of claim 1, where a material matrix of the conductive center region comprises amorphous silicon.

4. The infrared detector element of claim 1, where a material matrix of the conductive center region comprises vanadium oxide.

5. The infrared detector element of claim 1, where each of the first transition region, second transition region and conductive center region has a material matrix;

and where the material matrix of each of the transition regions has substantially the same molecular structure as the molecular structure of the matrix of the conductive center region.

6. The infrared detector element of claim 5, where the material matrix of each of the first transition region, second transition region and conductive center region comprises a semiconductor.

7. The infrared detector element of claim 6, where the conductive center region further comprises at least one additional material in an amount sufficient to impart a conductivity to the conductive center region that is greater than the conductivity of the first and second transition regions.

8. The infrared detector element of claim 6, where the conductive center region further comprises at least one additional material in an amount sufficient to impart a conductivity to the conductive center region that is greater than the conductivity of the first and second transition regions;

and where the additional material comprises at least one of hydrogen, germanium, fluorine, carbon, n-type dopant, p-type dopant, or a combination thereof.

9. The infrared detector element of claim 1, where a material matrix of each of the first transition region, second transition region and conductive center region comprises amorphous silicon.

10. The infrared detector element of claim 1, where a material matrix of each of the first transition region, second transition region and conductive center region comprises vanadium oxide.

11. The infrared detector element of claim 1, where at least one of the following conditions exists:

the first transition region decreases in conductivity in a graded manner between a higher value of conductivity at an interface between the conductive center region and the first transition region, and a lower value of conductivity at an interface between the first transition region and the first dielectric insulative layer;

or

the second transition region decreases in conductivity in a graded manner between a higher value of conductivity at an interface between the conductive center region and the second transition region, and a lower value of conductivity at an interface between the second transition region and the second dielectric insulative layer;

or a combination thereof.

12. The infrared detector element of claim 1, where the substrate comprises read out integrated circuitry (ROIC);

and where the infrared detector membrane is suspended in spaced relationship above the substrate and electrically coupled to the ROIC by thermal isolation legs.

13. The infrared detector element of claim 1, where the infrared detector membrane has at least one opening defined therein.

14. The infrared detector element of claim 13, where at least one opening comprises a plurality of openings configured as a grid of openings defined in the infrared detector membrane;

and where the infrared detector element comprises a diffractive resonant cavity (DRC) microbolometer structure and further comprises a reflector disposed between the substrate and the infrared detector membrane and having an upper surface configured to reflect infrared radiation.

15. A focal plane array, comprising a plurality of infrared detector elements of claim 1.

24. A method for making the infrared detector element of claim 1, comprising:

providing the substrate; and

forming the infrared detector membrane disposed in spaced relationship above the substrate by;

forming the first dielectric insulative layer in spaced relationship above a surface of the substrate,

forming the first transition region disposed on the first dielectric insulative layer,

forming the conductive center region disposed on the first transition region,

forming the second transition region disposed on the conductive center region, and

forming the second dielectric insulative layer disposed on the second transition region;

where at least a portion of each of the first and second conductive transition regions has a lower conductivity than the conductive center region and a greater conductivity than the first and second dielectric insulative layers.

25. The method of claim 24, further comprising forming the conductive center region to have a material matrix that comprises at least one of an amorphous silicon matrix, an amorphous silicon germanium matrix;

an amorphous silicon fluorine matrix;

an amorphous silicon carbon matrix, a vanadium oxide matrix, a vanadium oxide amorphous silicon matrix, a titanium oxide matrix, a germanium matrix, a silicon germanium oxide matrix, or a nickel manganite spinel matrix.

26. The method of claim 24, further comprising forming the conductive center region to have a material matrix that comprises at least one of amorphous silicon, vanadium oxide, or a combination thereof.

27. The method of claim 24, further comprising forming each of the first transition region, second transition region and conductive center region to have a material matrix that comprises at least one of amorphous silicon, vanadium oxide, or a combination thereof.

28. The method of claim 24, further comprising sequentially depositing each of the first transition region, conductive center region and second transition region in a continuous deposition process within the same deposition chamber.

29. The method of claim 24, further comprising forming each of the first transition region, second transition region and conductive center region such that a material matrix of each of the transition regions has substantially the same molecular structure as the molecular structure of a matrix of the conductive center region.

30. The method of claim 29, further comprising forming the conductive center region to comprise at least one additional material in an amount sufficient to impart a conductivity to the conductive center region that is greater than the conductivity of the first and second transition regions.

31. The method of claim 24, further comprising forming each of the first transition region, second transition region and conductive center region to have a material matrix that comprises amorphous silicon;

and forming the conductive center region to further comprise at least one additional material in an amount sufficient to impart a conductivity to the conductive center region that is greater than the conductivity of the first and second transition regions, the additional material comprising at least one of hydrogen, germanium, fluorine, carbon, n-type dopant, p-type dopant, or a combination thereof.

32. The method of claim 24, further comprising performing at least one of the following steps:

forming the first transition region to decrease in conductivity in a graded manner between a higher value of conductivity at an interface between the conductive center region and the first transition region, and a lower value of conductivity at an interface between the first transition region and the first dielectric insulative layer;

or

forming the second transition region to decrease in conductivity in a graded manner between a higher value of conductivity at an interface between the conductive center region and the second transition region, and a lower value of conductivity at an interface between the second transition region and the second dielectric insulative layer;

or

a combination thereof.

16. A transitioned device structure, comprising:

a first dielectric insulative layer;

a first transition region disposed on the first dielectric insulative layer;

a conductive center region disposed on the first transition region, the conductive center region forming a current conduction channel for the device structure;

a second transition region disposed on the conductive center region, and

a second dielectric insulative layer disposed on the second transition region;

where at least a portion of each of the first and second transition regions has a lower conductivity than the conductive center region and a greater conductivity than the first and second dielectric insulative layers so as to space the current conduction channel apart from the interface with each of the first and second dielectric insulative layers in a manner that shields the current conduction channel from the interface with each of the first and second dielectric insulative layers.

17. The device structure of claim 16, where each of the first transition region, second transition region and conductive center region has a material matrix;

and where the material matrix of each of the transition regions has substantially the same molecular structure as the molecular structure of the matrix of the conductive center region.

18. The device structure of claim 17, where the material matrix of each of the first transition region, second transition region and conductive center region comprises a semiconductor.

19. The device structure of claim 18, where the conductive center region further comprises at least one additional material in an amount sufficient to impart a conductivity to the conductive center region that is greater than the conductivity of the first and second transition regions.

20. The device structure of claim 18, where the conductive center region further comprises at least one additional material in an amount sufficient to impart a conductivity to the conductive center region that is greater than the conductivity of the first and second transition regions;

and where the additional material comprises at least one of hydrogen, germanium, fluorine, carbon, n-type dopant, p-type dopant, or a combination thereof.

21. The device structure of claim 16, where a material matrix of each of the first transition region, second transition region and conductive center region comprises amorphous silicon.

22. The device structure of claim 16, where at least one of the following conditions exists:

the first transition region decreases in conductivity in a graded manner between a higher value of conductivity at an interface between the conductive center region and the first transition region, and a lower value of conductivity at an interface between the first transition region and the first dielectric insulative layer;

or

the second transition region decreases in conductivity in a graded manner between a higher value of conductivity at an interface between the conductive center region and the second transition region, and a lower value of conductivity at an interface between the second transition region and the second dielectric insulative layer;

or a combination thereof.

23. The device structure of claim 16, where the device structure forms an infrared detector membrane disposed in spaced relationship above a substrate.

33. A method for making the transitioned device structure of claim 16, comprising:

forming the first dielectric insulative layer;

forming the first transition region disposed on the first dielectric insulative layer;

forming the conductive center region disposed on the first transition region to create a current conduction channel for the transitioned device structure;

forming a second transition region disposed on the conductive center region; and

forming the second dielectric insulative layer disposed on the second transition region;

where at least a portion of each of the first and second transition regions is formed to have a lower conductivity than the conductive center region and a greater conductivity than the first and second dielectric insulative layers so as to space the current conduction channel apart from the interface with each of the first and second dielectric insulative layers in a manner that shields the current conduction channel from the interface with each of the first and second dielectric insulative layers.

34. The method of claim 33, further comprising sequentially depositing each of the first transition region, second transition region and conductive center region in a continuous deposition process within the same vacuum chamber.

35. The method of claim 33, further comprising forming each of the first transition region, second transition region and conductive center region such that a material matrix of each of the transition regions has substantially the same molecular structure as the molecular structure of a matrix of the conductive center region.

36. The method of claim 35, further comprising forming the conductive center region to comprise at least one additional material in an amount sufficient to impart a conductivity to the conductive center region that is greater than the conductivity of the first and second transition regions.

37. The method of claim 36, further comprising forming each of the first transition region, second transition region and conductive center region to have a material matrix that comprises amorphous silicon;

and forming the conductive center region to further comprise at least one additional material in an amount sufficient to impart a conductivity to the conductive center region that is greater than the conductivity of the first and second transition regions, the additional material comprising at least one of hydrogen, germanium, fluorine, carbon, n-type dopant, p-type dopant, or a combination thereof.

38. The method of claim 33, further comprising performing at least one of the following steps:

forming the first transition region to decrease in conductivity in a graded manner between a higher value of conductivity at an interface between the conductive center region and the first transition region, and a lower value of conductivity at an interface between the first transition region and the first dielectric insulative layer;

or

forming the second transition region to decrease in conductivity in a graded manner between a higher value of conductivity at an interface between the conductive center region and the second transition region, and a lower value of conductivity at an interface between the second transition region and the second dielectric insulative layer;

or

a combination thereof.