The renewed interest in portable metrology equipment has led researchers towards the down-scaling of time and frequency standards, trying to retain the best possible performances. In this thesis, I assisted INRiM researchers in advancing their work on the miniaturization of atomic clocks based on two-photon doppler-free spectroscopy performed on alkali vapor microcells. Microcells’ fabrication was carried out in cleanroom environment, inside of PiQuET facility, through the implementation of standard Silicon technology techniques mutuated from the microelectronics community, including, but not limited to, photolithographic processes on Silicon wafers, metal layers depositions, DRIE and wafer bonding techniques. The quality of the cells was tested on an absorption spectroscopy setup inside the cleanroom, and their performance in terms of stability, precision and reliability was evaluated in the doppler-free two-photon spectroscopy setup used to implement the atomic clock.