Hybridized lead-salt infrared radiation detectors and methods of formation

• US 6,690,012 B1
• Filed: 10/11/2001
• Issued: 02/10/2004
• Est. Priority Date: 10/13/2000
• Status: Expired due to Term

• Current Assignee: L-3 Communications Corporation (L3Harris Technologies, Inc.)
• Original Assignee: Litton Systems Incorporated
• Inventors: Tibbitt, Jeffrey G., Sepulveda, Michael A., Jacksen, Niels F.
• Primary Examiner(s): Hannaher; Constantine
• Assistant Examiner(s): Gabor; Otilia
• Application Number:
  US09/976,191
• Time in Patent Office: 852 Days
• Field of Search: 250/338.1,338.4,332,349,370.08
• US Class Current: 250/338.1
• CPC Class Codes: H01L 27/14649 Infrared imagers
• CPC Class Codes: H01L 27/14683 Processes or apparatus peculiar to the manufacture or treatment of these devices or parts thereof not peculiar thereto H01L21/00
• CPC Class Codes: H01L 31/0324 comprising only AIVBVI or AIIBIVCVI chalcogenide compounds, e.g. Pb Sn Te

Abstract

A hybridized Lead-Salt infrared radiation detector includes a focal plane having a substrate and a sensitized, delineated Lead-Salt layer upon the substrate, the delineations forming a plurality of sections in a two-dimensional array. The detector also includes electrical contacts for each of the sections and a common grid between the sections. The detector further includes a layer of conductive barrier material on each electrical contact, a layer of passivating material on each section, and a layer of fusible conductive material on each layer of conductive barrier material.

Claims

1. A method for forming a hybridized Lead-Salt infrared radiation detector, the method comprising:

forming a focal plane array, comprising;

depositing a Lead-Salt layer upon a substrate,

sensitizing the Lead-Salt layer,

delineating the Lead-Salt layer into a plurality of sections, the sections forming a two-dimensional array,

forming electrical contacts for each of the sections and a common grid between the sections,

depositing a layer of conductive barrier material on each electrical contact,

depositing a layer of passivating material on each section, and

depositing a layer of fusible conductive material on each layer of conductive barrier materials;

depositing a layer of fusible conductive material on the electrical contacts of an integrated circuit; and

fusing the integrated circuit to the focal plane array.

2. The method of claim 1, wherein the Lead-Salt layer comprises Lead-Selenide.

3. The method of claim 1, wherein the electrical contacts and the common grid comprise Gold.

4. The method of claim 1, wherein the conductive barrier material comprises Palladium.

5. The method of claim 1, wherein the fusible conductive material comprises Indium.

6. The method of claim 1, wherein the passivation layer comprises Arsenic Tri-Selenide.

7. The method of claim 1, wherein the electrical contacts overlay at least part of the sections.

8. The method of claim 1, wherein the electrical contacts underlay at least part of the sections.

9. The method of claim 1, wherein the electrical contacts overlay and underlay at least part of the sections.

10. The method of claim 1, wherein depositing a passivation layer on each section comprises:

depositing the layer on the sections, the electrical contacts, and the conductive barrier layers;

patterning the layer over the electrical contacts; and

removing the patterned portions.

11. The method of claim 1, wherein the substrate comprises Z-Quartz.

12. The method of claim 1, further comprising producing a ground finish on the surface of the substrate where the Lead-Salt layer is to be deposited.

13. The method of claim 1, further comprising:

thinning the side of the substrate away from the Lead-Salt layer; and

polishing that side of the substrate.

14. The method of claim 1, wherein fusing the integrated circuit to the focal plane array comprises:

aligning the fusible conductive layers of the integrated circuit with the fusible conductive layers of the array; and

compressing the fusible conductive layers of the integrated circuit with the fusible conductive layers of the array.

15. The method of claim 1, wherein depositing a layer of fusible conductive material on the electrical contacts of an integrated circuit comprises:

providing an integrated circuit with exposed electrical contacts;

depositing a first layer of photoresist on the integrated circuit;

exposing the first layer of photoresist;

depositing a second layer of photoresist on the first layer of photoresist;

patterning the second layer of photoresist above the electrical contacts;

exposing the second layer of photoresist;

developing the first layer of photoresist and the second layer of photoresist so that the first layer undercuts the second layer and exposes the conductive barrier layers;

depositing a fusible conductive material on the integrated circuit; and

removing the first layer and second layer of photoresist.

16. The detector of claim 1, wherein the integrated circuit comprises a layer of conductive barrier material between each electrical contact and fusible conductive layer.

17. A hybridized Lead-Salt infrared radiation detector, the detector comprising:

a focal plane array, comprising;

a substrate,

a sensitized, delineated Lead-Salt layer upon the substrate, the delineations forming a plurality of sections in a two-dimensional array,

electrical contacts for each of the sections,

a common grid between the sections,

a layer of conductive barrier material on each electrical contact,

a layer of passivating material on each section, and

a layer of fusible conductive material on each layer of conductive barrier material; and

a layer of fusible conductive material on the electrical contacts of an integrated circuit, wherein the integrated circuit is fused to the array by fusing the fusible conductive layers of the integrated circuit with the fusible conductive layers of the array.

18. The detector of claim 17, wherein the electrical contacts and the common grid comprise Gold.

19. The detector of claim 17, wherein the conductive barrier material comprises Palladium.

20. The detector of claim 17, wherein the passivation layer comprises Arsenic Tri-Selenide.

21. The detector of claim 17, wherein the fusible conductive material comprises Indium.

22. The detector of claim 17, wherein the electrical contacts overlay at least part of the sections.

23. The detector of claim 17, wherein the electrical contacts underlay at least part of the sections.

24. The detector of claim 17, wherein the electrical contacts overlay and underlay at least part of the sections.

25. The detector of claim 17, wherein the Lead-Salt layer comprises Lead-Selenide.

26. The detector of claim 17, wherein the substrate comprises a ground finish on the surface where the Lead-Salt layer is to be deposited.

27. The detector of claim 17, wherein the substrate comprises Z-Quartz.

28. The detector of claim 27, wherein the side of the substrate opposite of the Lead-Salt layer is polished.

29. The detector of claim 17, wherein passivation layer overlays at least part of the electrical contacts and the conductive barrier layers.

30. A method for forming a hybridized Lead-Salt infrared radiation detector, the method comprising:

forming a focal plane array, comprising;

providing a Z-Quartz substrate,

depositing a conductive material on the substrate to form electrical contacts for each of a plurality of detector elements and a common grid between the detector elements,

depositing a Lead-Selenide layer upon the substrate, the electrical contacts, and the common grid,

sensitizing the Lead-Selenide layer,

delineating the Lead-Selenide layer into a plurality of sections, the sections forming a two-dimensional array,

depositing additional conductive material to extend the electrical contacts onto the sections and to form a second common grid between the detector elements,

depositing a layer of Palladium on each electrical contact,

selectively depositing a layer of Arsenic Tri-Selenide on the sections and at least part of the electrical contacts and the layers of Palladium,

depositing a layer of Indium on each layer of Palladium,

thinning the side of the substrate away from the Lead-Selenide layer, and

polishing the away side of the substrate;

preparing an integrated circuit, comprising;

providing an integrated circuit with exposed electrical contacts,

depositing a layer of Palladium on each electrical contact,

depositing a first layer of photoresist on the integrated circuit,

exposing the first layer of photoresist,

depositing a second layer of photoresist on the first layer of photoresist,

patterning the second layer of photoresist above the electrical contacts,

exposing the second layer of photoresist,

developing the first layer of photoresist and the second layer of photoresist so that the first layer undercuts the second layer and exposes the layers of Palladium,

depositing a layer of Indium on the integrated circuit, and

removing the first layer and second layer of photoresist; and

fusing the focal plane array to the integrated circuit.

31. A method for forming a hybridized Lead-Salt infrared radiation detector, the method comprising:

forming a focal plane array, comprising;

depositing a conductive material on a substrate to form electrical contacts for each of a plurality of detector elements and a common grid between the detector elements,

depositing a Lead-Sulfide layer upon the substrate, the electrical contacts, and the common grid,

delineating the Lead-Sulfide layer into a plurality of sections, the sections forming a two-dimensional array,

depositing additional conductive material to extend the electrical contacts onto the sections and to form a second common grid between the detector elements,

depositing a layer of Palladium on each electrical contact;

sensitizing the Lead-Sulfide layer,

depositing an Arsenic Tri-Selenide layer on the sections, the electrical contacts, and the layers of Palladium;

patterning the Arsenic Tri-Selenide layer above the electrical contacts,

removing the patterned portion by ion milling, and

depositing a layer of Indium on each layer of Palladium;

preparing an integrated circuit, comprising;

providing an integrated circuit with exposed electrical contacts,

depositing a layer of Palladium on each electrical contact,

depositing a first layer of photoresist on the integrated circuit,

exposing the first layer of photoresist,

depositing a second layer of photoresist on the first layer of photoresist,

patterning the second layer of photoresist above the electrical contacts,

exposing the second layer of photoresist,

developing the first of layer of photoresist and the second layer of photoresist so that the first layer undercuts the second layer and exposes the layers of Palladium,

depositing a layer of Indium on the integrated circuit, and

removing the first layer and second layer of photoresist; and

fusing the integrated circuit to the focal plane array.

32. A hybridized Lead-Salt infrared radiation detector, the detector comprising:

a focal plane array, comprising;

a substrate comprising Z-Quartz, the substrate having a ground finish on a surface where detector elements are formed and a polished surface on the opposite surface, the substrate being less than two-hundred microns thick,

a sensitized, delineated Lead-Selenide layer upon the polished surface of the substrate, the delineations forming a plurality of sections in a two-dimensional array,

electrical contacts for each of the sections, the electrical contacts underlaying and overlaying at least part of each of the sections,

a common grid that underlays the sections,

a second common grid that overlays the sections,

a layer of Palladium on each electrical contact, the layer providing a conductive chemical barrier between the electrical contacts and a future layer of Indium,

a layer of Arsenic Tri-Selenide material on each section and at least part of the electrical contacts and the layers of Palladium, and

a layer of Indium on each layer of Palladium, the layers providing fusible conductors; and

an integrated circuit comprising;

a plurality of electrical contacts,

a layer of Palladium on the electrical contacts, and

a layer of Indium on each layer of Palladium;

wherein the integrated circuit is fused to the focal plane array by having the Indium of the integrated circuit fused with the Indium of the array.

33. A hybridized Lead-Salt infrared radiation detector, the detector comprising:

a focal plane array, comprising;

a substrate,

a sensitized, delineated Lead-Sulfide layer upon the substrate, the delineations forming a plurality of sections in a two-dimensional array,

electrical contacts for each of the sections, the electrical contacts underlaying and overlaying at least part of the sections,

a common grid underlaying the sections,

a second common grid overlaying the sections,

a layer of Palladium on each electrical contact, the layer providing a conductive barrier between the electrical contacts and a future layer of Indium,

a layer of Arsenic Tri-Selenide on each section and at least part of the electrical contacts and the layers of Palladium, and

a layer of Indium on each layer of Palladium, the layers providing fusible conductors; and

an integrated circuit comprising;

a plurality of electrical contacts,

a layer of Palladium on the electrical contacts, and

a layer of Indium on each layer of Palladium;

wherein the integrated circuit is fused to the focal plane array by having the Indium of the integrated circuit fused with the Indium of the array.