Effect of thermal treatment on physical, electrical properties and reliability of porogen-containing and porogen-free ultralow-k dielectrics

Abstract

The effects of thermal annealing on the physical, electrical properties and reliability of porogen-containing and porogen-free ultralow-k dielectrics prepared by plasma-enhanced chemical vapor deposition (PECVD) are investigated. The porogen-free low-k dielectrics are obtained by using UV curing process to removal organic sacrificial phase and to generate open porosity. The results are compared with PECVD porogen-containing low-k films fabricated without UV curing process and PECVD low-k dielectrics deposited without organic sacrificial phase. The experimental results show that all low-k films remained stable after they were experimentally heating to temperatures up to 700°C. The non-porous low-k films also showed the highest reliability. Although the porous-free low-k film requires an additional UV curing process, the heat stress confirmed that its thermal stability was better than that of the porogen-containing low-k film. At an annealing temperature above 500°C, the heating process is comparable to UV curing, but does not provide SiOSi cross-linking within the film. At an annealing of 600°C, the porogen-free low-k films have a relatively higher breakdown electric-field and longer failure time in comparison to the porogen-containing low-k films. However, pores generated in porogen-containing low-k films at high temperature cause reliability to degrade with annealing temperature.