Wide band gap (WBG) materials (i.e. Silicon Carbide (SiC)) have attracted much attention in the semiconductor arena because of their significant properties (i.e. high capacitance, thermal stability, and wear resistance). It is widely known the Chemical Mechanical Planarization (CMP) of WBG substrates is a limiting step when it comes to manufacturing SiC containing devices. To increase removal rates, one must enable the formation of a soft, yet dense, oxide layer at the surface of the SiC material which is then removed by mechanical abrasion through hard abrasives and asperities on the surface of the polishing pad. These mechanically abrasive and chemically aggressive processes tend to use very high working pressures and sliding velocities which results in significant surface contamination post-CMP. Current p-CMP cleaning processes for SiC implement a polymer (Polyvinyl Alcohol (PVA)) brush scrubbing step coupled with aggressive surface modifying chemistries to enhance defect removal. Though this method of cleaning has proven to effectively aid in contaminate removal, secondary defects (i.e. scratches) can be induced due to the high shear force conditions. This research focuses on development of a low-stress non-contact post-CMP cleaning process for SiC. More specifically the use of megasonic energy in the presence of supramolecular assemblies such as micelles and vesicles were employed for a “soft” (low shear force) defect removal process. Initial results indicate a correlation between the structure of the “soft” cleaning additives and induced megasonic energy on overall simulated defect removal. It was determined that effective particle removal was a second order kinetic process with a concentration dependency (i.e. above and below the critical micelle concentration (CMC)) emerging as a key driver for the rate of defect removal. In addition, the use of megasonic energy with these supramolecular assemblies exhibited considerably lower secondary defect generation on the substrate surface post cleaning.

Megasonic Activation of Supramolecular Assemblies for Low Shear Stress Cleaning of Silicon Carbide

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