Low contact resistance of poly-plug structure by in-situ HF-vapour cleaning

A clustered tool, including in-situ HF-vapour cleaning, can be used to obtain a native-oxide-free silicon surface without exposing the surface to air after etching. This technique is attractive for the poly-plug process for dynamic random access storages (DRAMs) because the high aspect ratio contact in DRAMs can be easily cleaned using vapour phase HF cleaning. A comparison of four methods for contact hole cleaning is presented, including conventional wet HF-dipping and/or a new in-situ HF-vapour cleaning method.