Yutaka Ohira

The Possibility of Carbonyl Fluoride as a New CVD Chamber Cleaning Gas

Carbonyl fluoride (COF 2 ) has been investigated as an alternative gas for plasma-enhanced chemical vapor deposition (PECVD) chamber cleaning in order to reduce greenhouse gases emitted from the cleaning process in semiconductor manufacturing. The cleaning performance of COF 2 and the environmental impact of its exhaust gases were evaluated using an experimental plasma tool. The results indicated that the cleaning performance of COF 2 was equivalent to that of conventional C 2 F 6 . Furthermore, it was confirmed that the use of COF 2 would enable the reduction of global warming emissions by over 95% relative to the use of C 2 F 6 , and thus COF 2 is considered to be a promising alternative cleaning gas.

Evaluation of FNO and F3NO as substitute gases for semiconductor CVD chamber cleaning

Two types of FNO compounds (FNO and F 3 NO) were evaluated as candidates for new chemical vapor deposition (CVD) chamber cleaning gases. NF 3 and C 2 F 6 were measured as the reference. Like NF 3 , as these gases have no carbon in their molecules, no perfluoro carbon (PFC) is thought to be emitted. FNO is a compound highly susceptible to hydrolysis. F 3 ND is expected to decompose more easily than NF 3 in the atmosphere because its N-F bond has been weakened by introducing an N=O bond into the molecule. Hence, the contribution to global warming of these compounds is expected to be small. Performance of these gases was evaluated by measuring their etch rates and their exhaust gases. The results showed that the etch rate of F 3 NO is virtually the same as that of NF 3 , whereas the etch rate of FNO is about ½ that of NF 3 . However, from the results of exhaust gas analysis, it was found that an unexpected side reaction had occurred in the chamber, and therefore, it was confirmed that it is important to take this property into account in designing applications.