Method for forming a polysilicon node in a semiconductor device

A method for manufacturing a semiconductor device, comprising:

• forming a plurality of gate electrode structures on each of a cell area and a peripheral circuit area of a semiconductor substrate, wherein each of the plurality of gate electrode structures includes a capping layer stacked over a gate electrode, and spacers on respective opposite side walls of the gate electrode and the capping layer;
• forming an insulating layer on the cell area and the peripheral circuit area of the semiconductor substrate including the plurality of gate electrode structures;
• forming a self-aligned contact hole in the cell area to obtain a resultant structure, wherein the self-aligned contact hole is formed by removing a portion of the insulating layer which is contained in the cell area so as to expose a surface portion of the semiconductor substrate between adjacent spacers of respective adjacent gate electrode structures;
• forming a polysilicon layer over the cell area and the peripheral circuit area of the resultant structure;
• conducting a first etch back process of the polysilicon layer using a first etching reactant gas, and ceasing the first etch back process prior to exposing the capping layer of the gate electrode structures in the peripheral circuit area such that a portion of the polysilicon layer remains over the cell area and the peripheral circuit area;
• and
• conducting a second etch back process on the portion of the polysilicon layer using a second etching reactant gas so as to expose the capping layer of the gate electrode structures in the cell area and the peripheral circuit area and to obtain a polysilicon node which fills the self-aligned contact hole in the cell area,
• wherein an etching rate of the polysilicon layer is higher for the first etching reactant gas than for the second etching reactant gas, and wherein an etch selectivity ratio of the polysilicon layer to the capping layer is higher for the second etching reactant gas than for the first etching reactant gas.