Electromagnetic radiation detection structure with optimised absorption and method for forming such a structure

A detection structure of the bolometer type for detecting an electromagnetic radiation, the detection structure including:

• at least one absorbing element configured to absorb the electromagnetic radiation, said absorbing element defining an absorption plane,
• a transistor of MOS-FET type associated with the absorbing element to detect temperature rise of said absorbing element upon absorbing the electromagnetic radiation by the absorbing element, the transistor including:
• at least one first and one second zone of a first conductivity type,
• at least one third zone separating the first and second zones from each other, the third zone being of a second conductivity type opposite to the first conductivity type and having a lower concentration of majority carriers than that of the first and second zones,
• a gate electrode,
• wherein the first zone, the third zone, and the second zone are formed by a first layer, a third layer, and a second layer respectively, each of the first layer, the second layer, and the third layer extending parallel to the absorption plane, the first layer, the third layer, and the second layer following one another relative to a direction perpendicular to said absorption plane, each of the first zone, the second zone, and the third zone having, along the direction perpendicular to said absorption plane, at least one side wall,
• and wherein the gate electrode covers the third zone along at least one side wall of the third zone.

A method for manufacturing a detection structure of the bolometer type for detecting an electromagnetic radiation, the manufacturing method comprising:

• providing a second zone of a first conductivity type, said second zone extending along an absorption plane,
• forming a third zone in contact with the second zone, the second zone being of a second conductivity type opposite to the first conductivity type with a lower concentration of majority carriers than that of the second zone,
• forming a first zone in contact with the third layer, the first zone being of the first conductivity type with a higher concentration of majority carriers than that of the third zone, so that each of the first layer, the second layer, and the third layer extends parallel to an absorption plane and that the first layer, the third layer, and the second layer follow one another along a direction perpendicular to said absorption plane, each of the first zone, the second zone, and the third zone having, along the direction perpendicular to said absorption plane, at least one side wall,
• forming a gate electrode covering the third zone along at least one side wall of said third zone so as to form a MOS-FET transistor comprising the first zone, the second zone, and the third zone and the gate electrode,
• the manufacturing method further comprising forming an absorbing element associated with the transistor so that that the transistor is configured to detect the temperature rise of said absorbing element upon absorbing the electromagnetic radiation, said absorbing element defining the absorption plane.