Abstract: A method of cleaning a wafer, adapted for a patterned gate structure. The gate structures comprise a gate dielectric layer, a nitrogen-containing barrier layer and a silicon-containing gate layer sequentially stacked over the substrate. The method includes cleaning the substrate with phosphoric acid solution and hydrofluoric acid solution so that silicon nitride residues formed in a reaction between the nitrogen-containing barrier layer and the silicon-containing gate layer can be removed and the amount of pollutants and particles can be reduced. Ultimately, the yield of the process as well as the quality and reliability of the device are improved.

Abstract: A method of removing spacers after forming a MOS transistor on a wafer. The MOS transistor comprises a gate disposed on the substrate, spacers disposed on the sidewalls of the gate and a source and a drain region in the substrate beside the spacers. The spacers are removed by performing a wet etching process in the dark such that during the spacer removal process, the source and the drain region in a MOS transistor can be prevented from damages.

Abstract: A method for avoiding resist poisoning during a damascene process is disclosed. A semiconductor substrate is provided with a low-k dielectric layer (k?2.9) thereon, a SiC layer over the low-k dielectric layer, and a blocking layer over the SiC layer. The blocking layer is used to prevent unpolymerized precursors diffused out from the low-k dielectric layer from contacting an overlying resist. A bottom anti-reflection coating (BARC) layer is formed on the blocking layer. A resist layer is formed on the BARC layer, the resist layer having an opening to expose a portion of the BARC layer. A damascene structure is formed in the low-k dielectric layer by etching the BARC layer, the blocking layer, the SiC layer, and the low-k dielectric layer through the opening.