Microbolometer systems and methods
Microbolometer systems and methods are provided herein. For example, an infrared imaging device includes a substrate having contacts and a surface. The surface defines a plane. The infrared imaging device further includes a microbolometer array coupled to the substrate. Each microbolometer of the microbolometer array includes a cross-section having a first section, a second section substantially parallel to the first section, and a third section joining the first section and the second section.
1. An infrared imaging device comprising:
a substrate comprising a plurality of contacts and a surface, wherein the surface defines a plane;
a microbolometer array coupled to the substrate, wherein the microbolometer array comprises a plurality of microbolometers, and wherein each microbolometer comprises:
a bridge; and
a leg structure coupled to the bridge and to one of the plurality of contacts, wherein the leg structure comprises a conductive layer and a first layer disposed along at least two surfaces of the conductive layer.
2. The infrared imaging device of claim 1 , wherein the first layer is disposed along a first surface of the conductive layer and a second surface of the conductive layer substantially perpendicular to the first surface.
3. The infrared imaging device of claim 1 , wherein a height of the conductive layer is less than a height of the first layer.
4. The infrared imaging device of claim 3 , wherein the height of the conductive layer and the height of the first layer extend in a direction perpendicular to the plane, and wherein the first layer comprises a dielectric layer or a semiconductor layer.
5. The infrared imaging device of claim 1 , wherein the leg structure further comprises a second layer disposed along at least one surface of the conductive layer.
6. The infrared imaging device of claim 5 , wherein the first layer is disposed along at least three surfaces of the conductive layer and the second layer is disposed along at least three surfaces of the conductive layer such that the leg structure has an s-shaped cross-section or a z-shaped cross-section when viewed in a direction along a length of the leg structure.
7. The infrared imaging device of claim 1 , wherein the leg structure comprises:
a first segment having a first dimension that extends in a first direction that is substantially parallel to the plane and a second dimension that extends in a second direction that is substantially perpendicular to the plane, wherein the first dimension is greater than the second dimension; and
a second segment adjacent to the first segment, wherein the second segment has a third dimension that extends in the first direction and a fourth dimension that extends in the second direction, wherein the third dimension is less than the fourth dimension, and wherein each of the first segment and the second segment comprises a respective portion of the conductive layer and a respective portion of the first layer.
8. The infrared imaging device of claim 7 , wherein the leg structure further comprises a third segment adjacent to the second segment, and wherein the third segment comprises a respective portion of the conductive layer and a respective portion of the first layer.
9. The infrared imaging device of claim 1 , wherein the bridge comprises a resistive layer configured to capture infrared radiation, and wherein the conductive layer is in contact with the resistive layer.
10. The infrared imaging device of claim 9 , wherein the bridge comprises:
a first portion comprising:
a first insulator layer facing the substrate;
a second insulator layer; and
the resistive layer, wherein the resistive layer is disposed between the first insulator layer and the second insulator layer; and
a second portion having a plurality of perforations defined therein and being separate from and surrounding the first portion.
11. The infrared imaging device of claim 10 , wherein the first portion further comprises:
a third insulator layer; and
an absorber layer disposed between the second insulator layer and the third insulator layer.
12. A method of forming an infrared imaging device, the method comprising:
forming a bridge;
forming an opening in a sacrificial layer;
disposing a contact layer on sidewalls of the opening;
forming a leg structure that couples to the bridge and the contact layer, wherein the leg structure comprises a conductive layer and a first layer disposed along at least two surfaces of the conductive layer; and
removing the sacrificial layer to suspend the bridge and the leg structure above a substrate of the infrared imaging device, wherein the contact layer is coupled to the substrate.
13. The method of claim 12 , wherein the forming the leg structure comprises disposing the first layer along a first surface of the conductive layer and a second surface of the conductive layer substantially perpendicular to the first surface.
14. The method of claim 12 , wherein the forming the leg structure comprises disposing the first layer on the conductive layer such that a height of the conductive layer is less than a height of the first layer, and wherein the height of the conductive layer and the height of the first layer extend in a direction perpendicular to a plane defined by a surface of the substrate.
15. The method of claim 12 , wherein the forming the leg structure comprises:
disposing the first layer along at least two surfaces of the conductive layer; and
disposing a second layer along at least one surface of the conductive layer.
16. The method of claim 15 , wherein the first layer is disposed along at least three surfaces of the conductive layer and the second layer is disposed along at least three surfaces of the conductive layer such that the leg structure has an s-shaped cross-section or a z-shaped cross-section when viewed in a direction along a length of the leg structure, wherein the s-shaped cross-section or the z-shaped cross-section is maintained along the length of the leg structure, wherein the first layer comprises a dielectric layer or a semiconductor layer, and wherein the second layer comprises a dielectric layer or a semiconductor layer.
17. The method of claim 12 , wherein the leg structure comprises:
a first segment having a first dimension that extends in a first direction that is substantially parallel to a plane defined by a surface of the substrate and a second dimension that extends in a second direction that is substantially perpendicular to the plane, wherein the first dimension is greater than the second dimension; and
a second segment adjacent to the first segment, wherein the second segment has a third dimension that extends in the first direction and a fourth dimension that extends in the second direction, wherein the third dimension is less than the fourth dimension, and wherein each of the first segment and the second segment comprises a respective portion of the conductive layer and a respective portion of the first layer.
18. The method of claim 17 , wherein the leg structure further comprises a third segment adjacent to the second segment, and wherein the third segment comprises a respective portion of the conductive layer and a respective portion of the first layer.
19. The method of claim 12 , wherein the forming the bridge comprises:
forming a bridge structure comprising a resistive layer and one or more insulator layers; and
forming a plurality of perforations in the bridge structure to form the bridge such that the bridge comprises:
a first portion comprising the resistive layer; and
a second portion separate from and surrounding the first portion, wherein the second portion comprises the plurality of perforations formed therein.
20. The method of claim 19 , wherein:
the one or more insulator layers comprises a first insulator layer, a second insulator layer, and a third insulator layer;
the first portion comprises:
the first insulator layer facing the substrate;
the second insulator layer;
the resistive layer disposed between the first insulator layer and the second insulator layer; and
an absorber layer disposed between the second insulator layer and the third insulator layer.