The technology file contains antenna and DRC rules for the layers which is used by the Router to route and contact the cells during P&R phase.
The ICT/ITF file contains material details of each layer (resistivity, dielectric constants, temperature coefficients, etch values for conductors, min-space, min-width, etch vs. width vs. spacing) etc. details, which are used to generate nxtgrd/captable/qrcTechfile database. This database is used during extraction to extract device parasitic RC and wire RC from the final layout after P&R since RC affects timing.