Reduced stress electrode for focal plane array of thermal imaging system and method

A thermal detector including a focal plane array mounted with a thermal isolation structure on an integrated circuit substrate, comprising:

• a number of thermal sensors formed by an array of thermal sensitive elements bounded by a border;
• the thermal sensors providing a sensor signal output representative of thermal radiation incident to said focal plane array;
• a common electrode comprising a first layer in tension and a disparate second layer in compression, said electrode coupled to the thermal sensitive elements and to the border;
• a optical coating sensitive to infrared radiation disposed on the common electrode opposite from said thermal sensitive elements;
• said thermal isolation structure disposed between said focal plane array and said integrated circuit substrate, said thermal isolation structure projecting from said integrated circuit substrate for mounting said focal plane array to said integrated circuit substrate;
• and
• a number of contact pads disposed on said integrated circuit substrate for receiving the sensor signal output from the thermal sensors through said thermal isolation structure.

A method of fabricating a focal plane array for a thermal imaging system, comprising the steps of:

• forming an array of thermal sensitive elements bounded by a border from a wafer of thermal sensitive material;
• forming a first layer of a common electrode in tension and on one side of the thermal sensitive elements and the border;
• and
• forming a second layer of the common electrode in compression and on the first layer of the common electrode opposite from the array of thermal sensitive elements and the border.