Abstract: A method for forming a liner layer in silicon nitride spacers is disclosed. The method provides a semiconductor substrate having a polysilicon gate structure thereon. Then, as a key step of the present invention is forming a silicon oxynitride layer on the polysilicon gate structure and thereafter a silicon oxide layer is formed on the silicon oxynitride layer. Next, a conformal silicon nitride layer is formed on the semiconductor substrate and the silicon oxide layer. Moreover, on the sides of the silicon oxide layer, the spacers of silicon nitride are formed by anisotropically etching the silicon nitride layer.