Characterization of various low-k dielectrics for possible use in applications at temperatures below 160 deg. C

This study aims at the testing of various low-k insulators deposited at temperatures below approximately 160 deg. C for possible application in temperature-limited copper interconnects (e.g., in plastic electronics). Various polymers were tested such as the well-known poly(methyl methacrylate) (PMMA), a polyhedral oligomeric silsesquioxane (POSS) based copolymer partially fluorinated (POSS-F) and the newly synthesized poly(2,2,2-trifluoroethyl methacrylate) (PFEMA) and poly(dimethyl-siloxane) (PDMS). The above materials were compared with conventional spin-on glasses (SOGs), purchased from Filmtronics with respect to their handling (application, curing, mechanical strength, patterning) and dielectric constant. It was shown that organic polymers containing C-F bonds (PFEMA), Si-O bonds (PDMS) and Si-O and C-F bonds (POSS-F) present considerable advantages (related to the value of k and to handling) for use in Cu/low-k interconnects compared with usual SOGs cured at low temperatures