SiON Etch Characteristics Using Low-GWP C ₂ F ₄ O as a Replacement of CF ₄

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.