S-parameters-based high speed signal characterization of Al and Cu interconnect on low-K hydrogen silsesquioxane-Si substrate

Abstract

In this study, hydrogen silsesquioxane (HSQ) thin films are employed as the intermetal dielectric, and the high frequency characteristics of Al-HSQ and Cu/Ta-HSQ system are investigated and compared with those of Al-SiO2 system. The S-parameters of the interconnect are measured for insertion loss and crosstalk noise. The interconnect transmission parameters are extracted from the S-parameters. A figure of merit (FOM) is employed to evaluate the characteristics of the interconnect system at high frequencies (100MHz similar to 20GHz). It is found that the insertion losses are 2.01dB/mm, and 1.50dB/mm, 2.73dB/mm, 2.44dB/mm, and 1.66dB/mm at 10GHz, and 2.16dB/mm, 1.64dB/mm, 3.08dB/mm, 2.62dB/mm, and 1.82dB/mm at 20GHz for Al-SiO2, Al-HSQ, Al-HSQ (02 plasma), Cu/Ta-HSQ, and Cu/Ta-HSQ (NH3 plasma), respectively. The Al/HSQ system has better performance than the other ones do from 100MHz to 20GHz. The high frequency characteristics of Al and Cu interconnect with HSQ dielectrics are discussed.