A process architecture to fabricate CMOS image sensors allowing back-side illumination, each of the image sensors comprising CMOS devices and a matrix of photo-diodes, the photo-diodes incorporating epitaxially grown regions, the process comprising the steps of: (a) selecting a Thin-Film Silicon-On-Insulator, TF-SOI, or Thin-Film Germanium-On-Insulator, TF-GeOI, wafer comprising a top thin semiconductor film, said top thin semiconductor film being made of Silicon or made of Germanium (GeOI) and having a front side and a back side, a buried insulator having a front side and a back side, the front side of the buried insulator being provided in contact with the back side of the top thin semiconductor film, said wafer further comprising a bottom thick semiconductor substrate provided at the back side of the buried insulator; (b) fabricating the CMOS devices in the top thin semiconductor film; (c) epitaxially growing photo-diode active layers on the front side of the top thin semiconductor film; (c') making in-pixel capacitors directly on the epitaxially grown photo-diode active layers; (d) fabricating dense metal interconnects over each of the image sensor matrices, including over regions of the photo-diodes, on the front side of the top thin semiconductor film; (d') attaching the front side of the resulting structure to a temporary mechanical holder; (e) removing the bottom thick semiconductor substrate, after full processing of the front-side of the top thin semiconductor film; (f) fabricating monolithically integrated structures on the back surface of the buried insulator, aligned to the devices made on the top thin semiconductor film, wherein the monolithically integrated structures are either conventional color filters aligned with the photodiodes or Surface Plasmon Polariton light-funnel structures; (g) bonding a transparent mechanical substrate to the back surface of the buried insulator after fabricating the monolithically integrated structures and release from the temporary mechanical holder on the front side; (h) dicing and packaging each individual CMOS image sensor chip. (a) selecting a Thin-Film Silicon-On-Insulator, TF-SOI, or Thin-Film Germanium-On-Insulator, TF-GeOI, wafer comprising a top thin semiconductor film, said top thin semiconductor film being made of Silicon or made of Germanium (GeOI) and having a front side and a back side, a buried insulator having a front side and a back side, the front side of the buried insulator being provided in contact with the back side of the top thin semiconductor film, said wafer further comprising a bottom thick semiconductor substrate provided at the back side of the buried insulator; (b) fabricating the CMOS devices in the top thin semiconductor film; (c) epitaxially growing photo-diode active layers on the front side of the top thin semiconductor film; (c') making in-pixel capacitors directly on the epitaxially grown photo-diode active layers; (d) fabricating dense metal interconnects over each of the image sensor matrices, including over regions of the photo-diodes, on the front side of the top thin semiconductor film; (d') attaching the front side of the resulting structure to a temporary mechanical holder; (e) removing the bottom thick semiconductor substrate, after full processing of the front-side of the top thin semiconductor film; (f) fabricating monolithically integrated structures on the back surface of the buried insulator, aligned to the devices made on the top thin semiconductor film, wherein the monolithically integrated structures are either conventional color filters aligned with the photodiodes or Surface Plasmon Polariton light-funnel structures; (g) bonding a transparent mechanical substrate to the back surface of the buried insulator after fabricating the monolithically integrated structures and release from the temporary mechanical holder on the front side; (h) dicing and packaging each individual CMOS image sensor chip.