ScholarWorks@성균관대학교

초록

Etch profile control of high aspect ratio contact (HARC) is one of the key issues in developing next-generation memory device manufacturing because the HARC etch result can determine the device integration and device performance. In this study, the effect of F-based additive gases such as nitrogen trifluoride (NF3), tungsten hexafluoride (WF6), and molybdenum hexafluoride (MoF6) on the HARC SiO2 etching was investigated. A few sccm of NF3, WF6, and MoF6 added to the base gas recipe did not change the SiO2 etch rate and etch selectivity over the amorphous carbon layer (ACL) noticeably. However, the addition of NF3 flow enlarged the etched HARC SiO2 top hole size by decreasing the polymer layer thickness deposited on the sidewall. On the contrary, metal-containing additive gases such as WF6 and MoF6 resulted in decreased HARC SiO2 top hole size enlargement. For the base recipe and with NF3 addition, distorted and oval-shaped SiO2 bottom holes were observed possibly due to the charging of the SiO2 sidewall during the etching. But, for the addition of WF6 and MoF6, rather circular-shaped SiO2 bottom holes could be observed possibly due to the decreased SiO2 sidewall charging by the formation of a more conductive polymer through the inclusion of metals.

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