Characterization of various insulators for possible use as low-k dielectrics deposited at temperatures below 200 °C

The aim of this study was the testing of various low-k insulators deposited at temperatures below approximately 200 °C for use in copper interconnects. Various spin-on glasses (SOGs), purchased from Filmtronics Inc. and polymers such as the well-known poly(methyl methacrylate) (PMMA), the newly synthesized Poly(2,2,2 tri-fluoro-ethyl methacrylate) (PFEMA) and poly(dymethyl-siloxane) (PDMS) were tested. The above materials were compared with respect to their handling (application, curing, mechanical strength, patterning) and dielectric constant. It was shown that organic polymers containing C-F (PFEMA) and Si-O (PDMS) bonds 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.