Vertical microbolometer contact systems and methods

Abstract

Systems and methods are directed to vertical legs for an infrared detector. For example, an infrared imaging device may include a microbolometer array in which each microbolometer includes a bridge and a vertical leg structure that couples the bridge to a substrate such as a readout integrated circuit. The vertical leg structure may run along a path that is parallel to a plane defined by the bridge and may be oriented perpendicularly to the plane. The path may be disposed within, below, or above the plane defined by the bridge.

What is claimed as new and desired to be protected is: 
     
         1 . An infrared imaging device, comprising:
 a substrate having a plurality of contacts; and   a microbolometer array coupled to and disposed above the substrate having a surface that defines a plane, wherein each microbolometer comprises:
 a bridge; 
 a leg structure having at least a first portion that runs non-perpendicularly to the plane and runs between the bridge and at least one of the contacts; 
 wherein the first portion of the leg structure has a first dimension that extends in a direction that is substantially perpendicular to the plane; 
 wherein the first portion of the leg structure has a second dimension that extends in a direction that is substantially parallel to the plane; and 
 wherein the first dimension is greater than the second dimension. 
   
     
     
         2 . The infrared imaging device of  claim 1 , wherein the leg structure comprises a metal layer, a first dielectric layer formed on a first side of the metal layer, and a second dielectric layer formed on a second side of the metal layer. 
     
     
         3 . The infrared imaging device of  claim 1 , wherein:
 the first portion of the leg structure runs substantially parallel to the plane;   the substrate comprises a readout integrated circuit;   the at least one of the contacts comprises a contact structure that conductively couples the leg structure to the readout integrated circuit;   the contact structure comprises (i) a metal stud that extends from an end of the leg structure to the readout integrated circuit and (ii) an electrical contact on the readout integrated circuit; and   the leg structure further comprises a second portion that runs at a non-perpendicular angle from a first height above the substrate downward to the contact structure.   
     
     
         4 . The infrared imaging device of  claim 3 , wherein at least the first portion of the leg structure is disposed in a plane defined by the bridge. 
     
     
         5 . The infrared imaging device of  claim 3 , wherein at least the first portion of the leg structure is disposed below a plane defined by the bridge. 
     
     
         6 . The infrared imaging device of  claim 1 , wherein at least the first portion of the leg structure is disposed between the bridge and the substrate. 
     
     
         7 . The infrared imaging device of  claim 1 , wherein the leg structure comprises a metal layer having a vertical portion and a horizontal portion. 
     
     
         8 . The infrared imaging device of  claim 7 , wherein the leg structure further comprises a passivation layer formed on the horizontal portion and a dielectric material formed on at least the vertical portion, wherein the metal layer further comprises an additional horizontal portion that is substantially free of the passivation layer. 
     
     
         9 . The infrared imaging device of  claim 1 , wherein the leg structure comprises:
 a bend region; and   a pad comprised of a metal, or a dielectric, or a combination of metal and dielectric materials, wherein the pad is disposed in the bend region and is coupled to a vertical metal layer of the leg structure and disposed substantially perpendicular to the vertical metal layer.   
     
     
         10 . The infrared imaging device of  claim 1 , wherein the infrared imaging device comprises a focal plane array comprising the microbolometer array and the substrate. 
     
     
         11 . An infrared camera comprising the focal plane array of  claim 10 . 
     
     
         12 . A method of forming an infrared imaging device, the method comprising:
 providing a device having a bolometer bridge structure formed on a sacrificial layer;   depositing an additional sacrificial layer over the sacrificial layer;   forming openings in the additional sacrificial layer;   forming leg materials on sidewalls of the openings; and   removing the sacrificial layer and the additional sacrificial layer to suspend the bolometer bridge structure and the leg materials above a substrate of the infrared imaging device.   
     
     
         13 . The method of  claim 12 , wherein the forming of the leg materials comprises:
 depositing a first dielectric layer on portions of the sacrificial layer and the additional sacrificial layer;   performing a spacer etch of the first dielectric layer so that portions of the first dielectric layer remain on the sidewalls;   depositing a metal layer over the portions of the first dielectric layer on the sidewalls, over the bolometer bridge structure, and over a contact structure of the device;   depositing a second dielectric layer over the metal layer; and   removing portions of the metal layer and the second dielectric layer.   
     
     
         14 . The method of  claim 13 , wherein:
 the removing of the portions of the metal layer and the second dielectric layer comprises forming vertical leg structures for the infrared imaging device that run continuously from the bolometer bridge structure to the contact structure;   the vertical leg structure has (i) a first dimension that extends in a direction that is perpendicular to a plane defined by a surface of the substrate and (ii) a second dimension that extends in a direction that is parallel to the plane, wherein the first dimension is greater than the second dimension;   the infrared imaging device comprises a focal plane array; and   the method further comprises integrating the focal plane array into an infrared camera.   
     
     
         15 . The method of  claim 12 , wherein the device includes an etch stop layer on the sacrificial layer and wherein the depositing of the additional sacrificial layer over the sacrificial layer comprises depositing the additional sacrificial layer on the etch stop layer. 
     
     
         16 . A method of forming an infrared imaging device, the method comprising:
 providing a device having a bolometer bridge structure formed on a sacrificial layer;   forming openings in the sacrificial layer;   forming leg materials on sidewalls of the openings; and   removing the sacrificial layer to suspend the bolometer bridge structure and the leg materials above a substrate of the infrared imaging device.   
     
     
         17 . The method of  claim 16 , wherein the forming of the leg materials comprises:
 depositing a first dielectric layer on portions of the sacrificial layer;   performing a spacer etch of the first dielectric layer so that portions of the first dielectric layer remain on the sidewalls;   depositing a metal layer over the portions of the first dielectric layer on the sidewalls, over the bolometer bridge structure and, over a contact structure of the device;   depositing a second dielectric layer over the metal layer; and   removing portions of the metal layer and the second dielectric layer.   
     
     
         18 . The method of  claim 17 , wherein:
 the removing of the portions of the metal layer and the dielectric layer comprises forming vertical leg structures for the infrared imaging device that run continuously from the bolometer bridge structure to the contact structure;   the vertical leg structure has (i) a first dimension that extends in a direction that is perpendicular to a plane defined by a surface of the substrate and (ii) a second dimension that extends in a direction that is parallel to the plane, wherein the first dimension is greater than the second dimension;   the infrared imaging device comprises a focal plane array; and   the method further comprises integrating the focal plane array into an infrared camera.   
     
     
         19 . The method of  claim 16 , wherein:
 the device includes a passivation layer formed on the sacrificial layer, wherein the forming of the openings comprises forming the openings in the sacrificial layer and the passivation layer; and   the forming of the leg materials further comprises:
 forming a metal layer on the sidewalls, over portions of the passivation layer, over the bolometer bridge structure, and over a contact structure of the device; 
 forming a dielectric layer over the metal layer; and 
 removing portions of the metal layer and the dielectric layer. 
   
     
     
         20 . The method of  claim 19 , wherein:
 the removing of the portions of the metal layer and the dielectric layer comprises forming vertical leg structures for the infrared imaging device that run continuously from the bolometer bridge structure to the contact structure;   the vertical leg structure has (i) a first dimension that extends in a direction that is perpendicular a plane defined by a surface of the substrate and (ii) a second dimension that extends in a direction that is parallel to the plane, wherein the first dimension is greater than the second dimension;   the infrared imaging device comprises a focal plane array; and   the method further comprises integrating the focal plane array into an infrared camera.