Epitaxial growth of germanium photodetector for CMOS imagers

A method of fabricating a germanium photodetector comprising:

• preparing a silicon wafer as a silicon substrate;
• depositing a layer of silicon nitride on the silicon substrate;
• patterning and etching the silicon nitride layer;
• depositing a first germanium layer on the silicon nitride layer;
• patterning and etching the germanium layer wherein a portion of the germanium layer is in direct physical contact with the silicon substrate;
• depositing a layer of silicon oxide on the germanium layer wherein the germanium layer is encapsulated by the silicon oxide layer;
• annealing the structure at a temperature of between about 920° C. to 1000° C. in a RTA chamber for a time period of between about zero time and ten minutes;
• cooling the structure in ambient conditions;
• growing a second, single-crystal layer of germanium on the structure by liquid phase epitaxy;
• selectively removing the silicon oxide layer;
• implanting and activating ions to form N+ and P+ regions;
• and
• completing the germanium photodetector.

A method of fabricating a germanium photodetector comprising:

• preparing a silicon wafer as a silicon substrate, including fabricating a CMOS device on the silicon substrate;
• depositing a layer of silicon nitride on the silicon substrate;
• patterning and etching the silicon nitride layer;
• depositing a first germanium layer on the silicon nitride layer;
• patterning and etching the germanium layer wherein a portion of the germanium layer is in direct physical contact with the silicon substrate;
• depositing a layer of silicon oxide on the germanium layer wherein the germanium layer is encapsulated by the silicon oxide layer;
• annealing the structure at a temperature of between about 920° C. to 1000° C. in a RTA chamber for a time period of between about zero time and ten minutes;
• cooling the structure in ambient conditions;
• growing a second, single-crystal layer of germanium on the structure by liquid phase epitaxy;
• selectively removing the silicon oxide layer;
• implanting and activating ions to form N+ and P+ regions;
• and
• completing the germanium photodetector.