SiON Etch Characteristics Using Low-GWP C₂F₄O as a Replacement of CF₄

In semiconductor manufacturing, fluorocarbon gases such as CF₄, CHF₃, C₄F₈, etc., are widely used in dielectric etching. However, these gases are high global warming potential gases, therefore need to be replaced in the near future. Among these gases, CF₄ is the most difficult gas to be replaced due to its unique and simple structure in addition to its wide range of applications to various semiconductor processing. In this study, with the basic idea of having the same F/(C–O) ratio, trifluoroacetyl fluoride (C₂F₄O) was investigated as a potential CF₄ replacement by applying it to PR-masked SiON etching. Using both CF₄- and C₂F₄O-based gases, highly anisotropic SiON hole patterns could be successfully achieved; however, more stable SiON etch characteristics with O₂ flow rate could be achieved with C₂F₄O-based gas compared to CF₄-based gas. In addition, by using C₂F₄O-based gas instead of CF₄-based gas, the reduction of 24–29% in the emission of global warming gases could be achieved. Therefore, by using C₂F₄O instead of CF₄, not only process stability in the etching of SiON but also improved environmental effect could be achieved.