Abstract: A method for manufacturing a MOS device with improved well control stability. The method includes the steps of providing a semiconductor substrate; forming a gate electrode according to a critical dimension on the semiconductor substrate, wherein the gate electrode comprises a gate oxide layer and a conducting gate; inspecting a real dimension of the conducting gate; determining a thickness of subsequently formed conducting gate spacers according to the real dimension of the conducting gate, such that variations of electric characteristics of the device affected by the critical dimension of the conducting gate are reduced; and forming the conducting gate spacers with the determined thickness on sidewalls of the gate electrode.