Comparison Between E-beam and Ultraviolet Curing to Perform Porous a-SiOC:H

Porous ultralow- k films are required by the microelectronics industry as interlayer dielectrics for technologies and below. These porous insulating films can be deposited by plasma-enhanced chemical vapor deposition using a porogen approach. It consists of the codeposition of a matrix precursor and a sacrificial organic porogen, and then on a post-treatment to remove the organic porogen phase and create porosity in the film. In this work, an e-beam assisted thermal curing was compared to an ultraviolet-assisted thermal curing. Basic film properties such as , film shrinkage, porosity, pore size, and pore size distribution were evaluated. NMR and Fourier transform infrared analyses were used to study the chemical modifications induced by the post-treatment. These analyses show that the post-treatment impact depends on the radiation used. Both treatments lead to a removal of terminal nonbridging bonds such as , , and and can contribute to a subsequent formation of crosslinks. Both treatments remove methyls from , but the e-beam induces a bond increase while the UV bulb used decreases the contribution. The cross-linking improvement induces an increase of Young's modulus, the elastic properties being mainly correlated to the volumic bond concentration in the film.