Abstract : The introduction of high permittivity dielectrics so-called « High-Κ » can induce the appearance of until now neglected electrical behaviours. It is the case of the dielectric relaxation phenomenon. This thesis deals with this phenomenon in Metal-Insulator-Metal integrated in microelectronic. Through several amorphous dielectrics and one crystalline dielectric, two behaviours are identified, the « flat loss » one and the electrode polarization one. Since dielectric relaxation can degrade some chip performances, a model is proposed thanks to the creation of a memory effect test chip. Then a Ta2O5 MIM capacitors detailed analysis in term of leakage current stability and of low frequency permittivity variation, will allow identifying oxygen vacancies migration in dielectric. Finally, two solutions are proposed in order to suppress this issue. The first one consists in dielectric stacks deposition based on Ta2O5 performances. The second one proposes the integration of a new dielectric, the Zirconium oxide.