Invention relates to a method for fabrication of multilayer thin dielectric. Multilayer dielectric is formated by deposition of several layers of the same chemical composition on top of each other. At least two layers of Si3N4 are deposited on top of each other using chemical vapor deposition method in a chemical reaction between two gaseous reactants, wherein one reactant is a Si-containing gas and the other reactant is NH3 gas. After depositon of the first layer supply of Si-containing gas has been stopped and annealing the surface of the deposited layer is carried out at the temperature of 700-8000C in a flow of NH3 gas. The method prevents formation of pinhole defects in dielectric layers.