| 초록 |
In plasma etching of SiO2 layer, CF4 or NF3 gas has been exclusively used in micro-electronics manufacturing. Recently, there has emerged a new trend to replace CF4 with higher C/F ratio gases such as C2F6. It is because the C2F6 plasma more easily produces protective fluorocarbon polymers on the photoresist layer than CF4 and increases the selectivity of SiO2 etching. In this research, numerical study has been conducted on SiO2 dry etching using C2F6 plasma in an inductively coupled plasma (ICP) etcher, which is currently the most widely used plasma reactor for anisotropic etching. As a first step to design a run-to-run control system for the ICP etcher, the purpose of the study has been placed in investigating the effects of operating variables such as RF power, bias voltage, pressure, gas flow rate etc on the plasma state and furthermore on the etch rate and uniformity. A commercial CFD code called CFD-ACE was used for plasma simulation and TOPO for feature scale simulation of SiO2 etching. As a result, within the concerned ranges of operating variables, it was discovered that increasing RF power, bias voltage, and decreasing pressure enhance the etch rate. Lowering the RF power alone gives better performance in uniformity. |
