Pixel for uncooled infrared focal plane detector and preparation method therefor

A method of preparing a pixel of an uncooled infrared focal plane detector, comprising:

• step 1, providing a semiconductor substrate comprising a readout integrated circuit;
• depositing a metal layer on the semiconductor substrate;
• patterning the metal layer to form a metal reflection layer pattern and a metal electrode block;
• wherein the metal electrode block is electrically connected to the readout integrated circuit on the semiconductor substrate;
• depositing an insulation dielectric layer on the patterned metal layer;
• depositing a first sacrificial layer on the insulation dielectric layer, and performing a planarization processing on the first sacrificial layer;
• depositing a SiO2 film on the first sacrificial layer as a first support layer after the planarization processing is completed;
• and
• depositing a silicon nitride film on the first support layer as a protection layer for the first support layer;
• step 2, etching a first through-hole by a method of photolithography and reactive ion etching in a direction from the protection layer for the first support layer to the semiconductor substrate, wherein the etching of the first through-hole is ended at the metal electrode block that is electrically connected to the readout integrated circuit;
• step 3, depositing a first metal electrode layer on the protection layer for the first support layer and at the bottom of the first through-hole, and patterning the first metal electrode layer to form a metal wiring and a metal electrode;
• depositing a first silicon nitride dielectric layer on the patterned first metal electrode layer;
• and
• sequentially etching, vertically downward from the first silicon nitride dielectric layer, the first silicon nitride dielectric layer, the first metal electrode layer, the protection layer for the first support layer and the first support layer to form a bridge leg structure, wherein the etching is ended at the first sacrificial layer;
• step 4, depositing a second sacrificial layer on the bridge leg structure, and performing a planarization processing on the second sacrificial layer,
• depositing a SiO2 film as a second support layer on the second sacrificial layer after the planarization processing is completed;
• depositing a silicon nitride film on the second support layer as a protection layer for the second support layer;
• etching a second through-hole by a method of photolithography and reactive ion etching in a direction from the protection layer for the second support layer to the first metal electrode layer, wherein the etching of the second through-hole is ended at the first metal electrode layer;
• step 5, depositing a thermal sensitive layer on the protection layer for the second support layer, and patterning the thermal sensitive layer;
• step 6, depositing a silicon nitride film as a protection layer for the thermal sensitive layer on the thermal sensitive layer after the patterning the thermal sensitive layer is completed,
• patterning the protection layer for the thermal sensitive layer;
• etching, by a method of photolithography and reactive ion etching on the protection layer for the thermal sensitive layer after the patterning the protection layer for the thermal sensitive layer is completed, part of the protection layer for the thermal sensitive layer which is on the thermal sensitive layer, such that and a contact hole is formed to expose the thermal sensitive layer;
• step 7, depositing a second metal electrode layer on the protection layer for the second support layer, the protection layer for the thermal sensitive layer, the contact hole and the bottom of the second through-hole, and patterning the second metal electrode layer;
• step 8, depositing a second silicon nitride dielectric layer on the second metal electrode layer after the patterning the second metal electrode layer is completed, and patterning the second silicon nitride dielectric layer;
• step 9, sequentially etching, vertically downward from the second silicon nitride dielectric layer after the patterning the second silicon nitride dielectric layer is completed, the second silicon nitride dielectric layer, the second metal electrode layer, the protection layer for the thermal sensitive layer, the thermal sensitive layer, and the protection layer for the second support layer, wherein the etching is ended at the second sacrificial layer, and a thermal conversion structure including micro bridge legs and a thermal sensitive structure is formed;
• step 10, depositing a third sacrificial layer on the thermal conversion structure including the micro bridge legs and the thermal sensitive structure, and performing a planarization processing on the third sacrificial layer;
• depositing a SiO2 film as a third support layer on the third sacrificial layer after the planarization processing is completed;
• depositing an absorption layer film on the third support layer as an absorption layer;
• and
• depositing a silicon nitride film on the absorption layer as a protection layer of the absorption layer, and an absorption layer structure is formed;
• step 11, sequentially etching, vertically downward from the protection layer of the absorption layer, the protection layer of the absorption layer, the absorption layer and the third support layer, wherein the etching is ended at the third sacrificial layer;
• removing the first sacrificial layer, the second sacrificial layer and the third sacrificial layer, such that the pixel of the uncooled infrared focal plane detector is obtained.