Bake-stable HgCdTe photodetector and method for fabricating same

Abstract

A photoresponsive device and a method of fabricating same, wherein the device includes semiconductor material, such as a cap region (14a), comprised of elements selected from Group IIB-VIA. A molybdenum contact pad (16) is formed upon a surface of the cap region, and a molybdenum ground contact pad is formed on a surface of a base region (12). A wide bandgap semiconductor passivation layer (20) overlies the surface of cap region and also partially overlies the molybdenum contact pad. A dielectric layer (22) overlies the passivation layer, and an indium bump (24) is formed upon the molybdenum contact pad. The indium bump extends upwardly from the molybdenum contact pad and through the dielectric layer. The dielectric layer is in intimate contact with side surfaces of the indium bump such that no portion of the molybdenum contact pad can be physically contacted from a top surface of the dielectric layer. The method eliminates the possibility of unwanted chemical reactions occurring between the In and the underlying contact pad metal. The method also deposits the contact metal before the deposition of the passivation and before a high temperature anneal, with windows to the contact being opened after the anneal so as to reduce localized stresses at the edges of the windows.

Dependencies are inferred from the claim text.