Infrared detector having a directly bonded silicon substrate present on top thereof
A direct bonding method for infrared focal plane arrays, includes steps of depositing a thin adhesion layer on infrared radiation detecting material, removing a portion of the thin adhesion layer with a chemical-mechanical polishing process, forming a bonding layer at a bonding interface, and bonding the infrared radiation detecting material to a silicon wafer with the thin adhesion layer as a bonding layer. The thin adhesion layer may include SiO x , where x ranges between 1.0 and 2.0. The thickness of the thin adhesion layer to form the bonding layer is 500 angstrom or less.
1. A direct bonding method for frontside-illuminated infrared focal plane arrays, comprising:
depositing a thin adhesion layer on infrared radiation detecting material such that a thickness of the thin adhesion layer is 1000 angstroms or less, wherein the thin adhesion layer is optically transparent;
removing a portion of the thin adhesion layer with a chemical-mechanical polishing process;
forming a bonding layer at a bonding interface; and
bonding the infrared radiation detecting material to a silicon wafer with the thin adhesion layer as the bonding layer.
2. The method of claim 1 , further comprising:
providing an infrared wafer including the infrared radiation detecting material; and
wherein bonding the infrared radiation detecting material further comprises directly bonding the infrared wafer to the silicon wafer via the thin adhesion layer such that the infrared wafer having a silicon substrate present on top thereof is provided.
3. The method of claim 1 , wherein removing the portion of the thin adhesion layer further comprises polishing the portion of the thin adhesion layer with a chemical-mechanical polishing process such that a thickness of the thin adhesion layer is 500 angstroms or less.
4. The method of claim 1 , wherein depositing the thin adhesion layer further comprises forming the thin adhesion layer from infrared transparent materials.
5. The method of claim 1 , wherein depositing the thin adhesion layer further comprises forming the thin adhesion layer with a silicon monoxide material.
6. The method of claim 5 , wherein forming the thin adhesion layer further comprises forming the thin adhesion layer with SiO x , where x is in the range of 1.0˜2.0.
7. The method of claim 1 , wherein forming the bonding layer comprises forming no epoxy layer at the bonding interface.
8. The method of claim 7 , wherein forming the bonding layer comprises forming no anti-reflective coating layer at the bonding interface.
9. A direct bonding method for infrared detector wafers, comprising:
polishing a first surface of an infrared detector wafer with a chemical-mechanical polishing (CMP) process;
depositing a SiO x layer on the first surface, where x ranges 1.0 to 2.0;
polishing a second surface of the SiO x layer to have a predetermined thickness;
polishing a third surface of a silicon wafer with the CMP process; and
directly bonding the second surface of the infrared detector wafer to the third surface of the silicon wafer.
10. The method of claim 9 , further comprising depositing the SiO x layer to have a thickness of the thin IR transparent adhesion layer of 1000 angstroms or less.
11. The method of claim 9 , wherein polishing the second surface of the SiO x layer further comprises removing a portion of the SiO x layer to have a thickness of the thin IR transparent adhesion layer of 500 angstroms or less.
12. The method of claim 9 , wherein the step of directly bonding further comprises:
plasma activating the infrared detector wafer and the silicon wafer; and
cleaning the infrared detector wafer and the silicon wafer.
13. The method of claim 9 , further comprising annealing the infrared detector wafer and the silicon wafer subsequent to direct bonding of the second and the third surfaces.