Method of forming photonics structures
View Patent ↗The disclosed embodiments relate to an integrated circuit structure and methods of forming them in which photonic devices are formed on the back end of fabricating a CMOS semiconductor structure containing electronic devices. Doped regions associated with the photonic devices are formed using microwave annealing for dopant activation.
1. A method for fabricating an integrated structure, the method comprising:
fabricating a CMOS structure containing an electronic device over a substrate, wherein the electronic device is formed using a first semiconductor material;
fabricating a second semiconductor material over the first semiconductor material;
fabricating a buried oxide material between the first semiconductor material and the second semiconductor material,
fabricating a photonic device using the second semiconductor material, the photonic device comprising a modulator having associated doped regions and a photodetector; and
activating the doped regions with microwave energy such that the doped regions are heated to a temperature in the range of about 200 to about 500 degrees Celsius,
wherein the buried oxide material is configured to function as a cladding for the photonic device.
2. The method according to claim 1 , wherein the doped regions are heated to a temperature within the range of about 300 to about 400 degrees Celsius.
3. The method according to claim 1 , wherein the second semiconductor material is thicker than the first semiconductor material in which the electronic device of the CMOS structure is formed.
4. The method according to claim 1 , wherein the buried oxide material has a thickness greater than or equal to 1 micrometer and the second semiconductor material has a thickness greater than or equal to 200 nanometers.
5. The method according to claim 1 , wherein the dopant is heated with microwave energy for at least about five minutes.
6. The method according to claim 5 , wherein the dopant is heated with microwave energy for up to about two hours.
7. The method according to claim 1 , wherein the activating step occurs using microwave at a frequency greater than or equal to about 1.5 GHz and less than or equal to about 8.5 GHz.
8. The method according to claim 1 , wherein the activating step occurs using microwaves at a frequency of about 2.45 GHz and at a power of about 1300 W.
9. The method according to claim 1 , wherein fabricating the photonic device comprises forming a waveguide using the second semiconductor material and a photodetector material in association with the waveguide.
10. The method according to claim 9 , wherein the activating occurs before forming the photodetector material.
11. The method according to claim 9 , wherein the activating occurs after forming the photodetector material.
12. The method according to claim 10 , wherein the photodetector material comprises one of germanium and silicon-germanium.
13. The method according to claim 1 , further comprising forming an electrical connection between a metallization material and the photonic device.
14. The method according to claim 13 , further comprising forming an electrical connection between a metallization material associated with an electronic device in the CMOS structure and a metallization material associated with the photonic device.
15. The method according to claim 1 , wherein the photonic device is fabricated after forming the first semiconductor material over the fabricated CMOS structure.