The manufacturing method of semiconductor device

A method for manufacturing a semiconductor device is provided to obtain a high dielectric gate oxide by using an interface reaction between an oxide layer and a metal layer. An oxide layer(20) is formed on a silicon substrate(10). A metal layer(30) is deposited on the oxide layer. A metal silicate layer(40) is formed between the oxide layer and the metal layer by using an interface reaction between the oxide layer and the metal layer. A metal gate is formed by etching the metal silicate layer and the metal layer. An LDD(Lightly Doped Drain) region and source/drain electrodes are formed on the silicon substrate. The interface reaction is induced by performing a thermal process after the metal layer is deposited on the oxide layer or by using kinetic energy caused by a deposition process of the metal layer on the oxide layer.