Micromachined optical mechanical modulator based transmitter/receiver module

A method for manufacturing a mechanical modulator based and all elements integrated WDM transmitter/receiver module including a Fabry-Perot cavity consisting of a top mirror and its supporting beams, a middle supporting frame, a middle air gap, a bottom mirror, a photodiode mounded above said cavity, and a conic hole for receiving an optical fiber, comprising the steps of:

• forming a p-type silicon cone surrounded by a n-type diffusion silicon layer in a p-type single crystalline silicon substrate;
• depositing a bottom un-doped polysilicon layer on the surface of said p-type single crystalline silicon substrate and thereafter forming a plurality of small heavily doped polysilicon regions in said bottom layer which partially cover said underlying p-type silicon cone;
• depositing a middle un-doped polysilicon layer on the surface of said bottom un-doped polysilicon layer, and then doping a portion of the middle un-doped polysilicon layer to create a large central heavily doped region partially covering said underlying small heavily doped polysilicon regions and having a plurality of small un-doped polysilicon regions that are scattered therein and stand on the surface of said underlying un-doped polysilicon layer;
• depositing a top un-doped polysilicon layer of the surface of said middle un-doped polysilicon layer;
• creating a plurality of openings in said top un-doped polysilicon layer so as to partially expose said underlying heavily doped region of said middle un-doped polysilicon layer and define an un-released polysilicon membrane and its supporting polysilicon beams from said top un-doped polysilicon layer;
• performing anodization in HF solution to turn all said heavily doped polysilicon into porous polysilicon and the p-type silicon of said p-type silicon cone into porous single crystalline silicon;
• thinning said single crystalline silicon substrate from its back side to reveal said porous single crystalline silicon;
• bonding a rigid plate with a throughout hole onto the back side of said thinned single crystalline silicon substrate so as to align said throughout hole with said revealed porous single crystalline silicon;
• removing said porous polysilicon and said porous single crystalline silicon in diluted alkali solution for the partial release of said top polysilicon membrane and its supporting polysilicon beams, for the final release of a bottom polysilicon membrane, and for forming a conic hole in said single crystalline silicon substrate;
• depositing an anti-reflective layer on the back surface of said bottom polysilicon membrane;
• removing the un-doped polysilicon on the top of said a plurality of small un-doped regions of said middle un-doped polysilicon layer and the un-doped polysilicon of said a plurality of small un-doped regions of said middle un-doped polysilicon layer polysilicon by dry etching for the final release of said polysilicon membrane and its supporting polysilicon beams;
• mounting a photodiode on the top of said single crystalline silicon substrate and
• inserting an optical fiber into said conic hole of said single crystalline silicon substrate through said throughout hole of said rigid plate.