Silicon Oxide Etching Process of NF3 and F3NO Plasmas with a Residual Gas Analyzer

The use of NF3 is significantly increasing every year. However, NF3 is a greenhouse gas with a very high global warming potential. Therefore, the development of a material to replace NF3 is required. F3NO is considered a potential replacement to NF3. In this study, the characteristics and cleaning performance of the F3NO plasma to replace the greenhouse gas NF3 were examined. Etching of SiO2 thin films was performed, the DC offset of the plasma of both gases (i.e., NF3 and F3NO) was analyzed, and a residual gas analysis was performed. Based on the analysis results, the characteristics of the F3NO plasma were studied, and the SiO2 etch rates of the NF3 and F3NO plasmas were compared. The results show that the etch rates of the two gases have a difference of 95% on average, and therefore, the cleaning performance of the F3NO plasma was demonstrated, and the potential benefit of replacing NF3 with F3NO was confirmed.

Comparison of Different Ways of Extra Phosphorus Implantation Which Decrease the Threshold Voltage and On-resistance of UMOS

A method to decrease the threshold voltage and on-resistance is discussed in this paper, which is adding extra phosphorus implantation into silicon. There are two ways to implant extra phosphorus without adding a mask. The first way is to implant extra phosphorus after the field oxide etching, and the second way is to implant extra phosphorus with the source region mask before the N+ implantation. Compare the results of the two ways to find their characteristics and choose the appropriate one.

Highly Selective Etching between Different Oxide Films by Vapor Phase Cleaning

VPC (Vapor Phase Cleaning) is studied to etch various types oxide film using a mixture of HF gas and H2O vapor. We focused on controlling the amount of gas molecules adsorbed on the oxide surface and investigated the H2O amount included in oxide films, which will contribute to the oxide etching reaction. We have verified that selective etching between different oxide films can be achieved by controlling the gas adhesion amount by varying process parameters and utilizing the different amounts of H2O in the oxide films for several deposition methods.