Infrared sensor and its reference element and manufacturing method of the reference element

An infrared sensor, comprising:

• a reference element, comprising:
• a first substrate;
• a sacrificial layer disposed on the first substrate;
• a first supporting structure disposed on the first substrate, wherein a top surface of the first supporting structure is coplanar with a top surface of the sacrificial layer;
• a fence structure disposed on the first substrate and surrounding the sacrificial layer, with a top surface of the fence structure being coplanar with the top surface of the sacrificial layer, and an air gap being between the fence structure and the first supporting structure;
• and
• a first infrared sensing structure disposed on the sacrificial layer, the first supporting structure and the fence structure and having an opening corresponding to the air gap;
• and
• a sensing element, comprising:
• a second substrate;
• a second supporting structure disposed on the second substrate;
• and
• a second infrared sensing structure disposed on the second supporting structure;
• wherein the first infrared sensing structure and the second infrared sensing structure are coplanar with each other.

A manufacturing method of a reference element of an infrared sensor, comprising:

• forming a sacrificial layer on a substrate;
• embedding a supporting structure and a fence structure into the sacrificial layer, wherein a top surface of the sacrificial layer, a top surface of the supporting structure and a top surface of the fence structure are coplanar with each other;
• forming an infrared sensing structure on the sacrificial layer, the supporting structure and the fence structure;
• and
• forming an opening in an area of the infrared sensing structure corresponding to an area between the supporting structure and the fence structure to release a part of the sacrificial layer between the supporting structure and the fence structure.