Infrared sensor having improved sensitivity and reduced heat generation

An infrared sensor comprising:

• a semiconductor substrate;
• a first infrared absorbing portion provided on the semiconductor substrate, having a first surface facing the semiconductor substrate and a second surface opposite to the first surface;
• an infrared sensing portion for sensing infrared rays based on infrared rays absorbed by the first infrared absorbing portion;
• a plurality of protrusions including metal or a silicon nitride film, and disposed apart from each other on the second surface of the first infrared absorbing portion;
• and
• a second infrared absorbing portion, which is formed so as to contact and cover a top surface and a side surface of the plurality of protrusions, and which is provided on top surfaces of the first infrared absorbing portion,
• wherein spaces between adjacent protrusions of the plurality of protrusions are wholly filled with the second infrared absorbing portion such that there is no gap between adjacent protrusions.