Infrared detection sensor and method of fabricating the same
View Patent ↗In an infrared detection sensor according to the present invention, all material constituting an upper portion of a sensing electrode in a supporting arm region is removed so that a supporting arm has low thermal conductivity. As a result, thermal conductivity of the infrared sensor structure is reduced, and the infrared detection sensor has excellent sensitivity.
1. An infrared detection sensor, comprising:
a substrate on which a metal pad and a reflection layer are formed;
a sensor structure spaced a predetermined distance from the reflection layer and including a sensing layer having a resistance value which is varied according to a change in temperature, a lower protection layer formed below the sensing layer and an upper protection layer formed on the sensing layer;
an anchor formed on the metal pad and having a predetermined thickness, the anchor including the sensing layer, a sensing electrode formed below the sensing layer to transmit a change in resistance of the sensing layer to the metal pad, the lower protection layer and the upper protection layer; and
a supporting arm extending from the anchor to support the sensor structure,
wherein the sensing layer formed on the sensing electrode and the upper protection layer are removed from the supporting arm region to form the supporting arm composed of the sensing electrode and the lower protection layer.
2. The infrared detection sensor of claim 1 , wherein the substrate comprises a read-out integrated circuit formed therein and the metal pad is electrically connected to the read-out integrated circuit.
3. The infrared detection sensor of claim 1 , wherein the sensing layer is formed of one of amorphous silicon, polycrystalline silicon and vanadium oxide.
4. The infrared detection sensor of claim 1 , wherein the sensing electrode is formed of one of titanium, titanium nitride and a nickel-chrome alloy.
5. The infrared detection sensor of claim 1 , wherein the lower protection layer and the upper protection layer are formed of a silicon nitride layer or a silicon oxide layer.
6. A method of fabricating an infrared detection sensor, comprising;
forming a metal pad and a reflection layer on a substrate in which a read-out integrated circuit is formed, and forming a sacrificial layer having a predetermined thickness on the substrate;
forming a lower protection layer on the sacrificial layer, and forming a sensing electrode on an anchor region and a supporting arm region;
forming a sensing layer to cover the sensing electrode, and forming an upper protection layer on the sensing layer;
patterning the upper protection layer, the sensing layer and the lower protection layer, and forming a sensor structure and a supporting arm; and
etching the sacrificial layer,
wherein, in patterning the upper protection layer, the sensing layer and the lower protection layer, the upper protection layer and the sensing layer formed on the sensing electrode in the supporting arm region are removed by the patterning process to form the supporting arm composed of the sensing electrode and the lower protection layer.
7. The method of claim 6 , wherein forming the metal pad and the reflection layer further comprises forming an anchor pattern on the sacrificial layer to expose the metal pad.
8. The method of claim 7 , wherein forming the lower protection layer on the sacrificial layer comprises;
forming a lower protection layer on the sacrificial layer on which the anchor pattern is formed;
forming a contact hole on the lower protection layer to expose the metal pad;
forming the sensing electrode in contact with the exposed metal pad; and
patterning the sensing electrode such that the sensing electrode remains on the anchor region and the supporting arm region.
9. The method of claim 8 , wherein the sensing electrode is formed of one of titanium, titanium nitride and a nickel-chrome alloy.
10. The method of claim 6 , wherein the sensing layer is formed of one of amorphous silicon, polycrystalline silicon and vanadium oxide.
11. The method of claim 6 , wherein patterning the upper protection layer, the sensing layer and the lower protection layer comprises:
forming a photoresist pattern on a sensor structure region and the anchor region; and
dry etching the upper protection layer and the sensing layer formed on the sensing electrode in the supporting arm region using the photoresist pattern, forming the supporting arm composed of the sensing electrode and the lower protection layer by stopping the etching on the sensing electrode, and dry etching and patterning the upper protection layer, the sensing layer and the lower protection layer using the photoresist pattern to form a sensor structure.
12. The method of claim 11 , wherein, in dry etching the upper protection layer and the sensing layer formed on the sensing electrode in the supporting arm region, the upper protection layer, the sensing layer and the lower protection layer are dry-etched by means of plasma using a mixture gas composed of at least one of tetrafluoromethane (CF 4 ), fluoroform (CHF 3 ), argon (Ar) and oxygen (O).