Characterization and optimization of porogen-based PECVD deposited extreme low- k materials as a function of UV-cure time

• Published in: Surface & coatings technology Vol. 201; no. 22; pp. 9264 - 9268
• Main Authors: Verdonck, Patrick, De Roest, David, Kaneko, Shinya, Caluwaerts, Rudy, Tsuji, Naoto, Matsushita, Kiyohiro, Kemeling, Nathan, Travaly, Youssef, Sprey, Hessel, Schaekers, Marc, Beyer, Gerald
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Lausanne Elsevier B.V 25-09-2007; Elsevier
• Subjects: 52.75R; 77.55; 78.20C; 81.05R; 81.40T; Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Low- k material; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; PECVD; Physics; Porogen; UV cure; UV cure; Porogen; 52.75R; 81.40T; Low- k material; PECVD; 78.20C; 77.55; 81.05R; CVD; Surface treatments; PECVD; Low-k material; Porogen; UV cure; 77.55; 52.75R; 81.05R; 78.20C; 81.40T
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2007.04.096

A promising method to produce low-
k films with a dielectric constant,
k, less than 2.3, consists in using a porogen-based PECVD process in combination with UV cure for both porogen removal and thermo-mechanical properties enhancement. Aurora® ELK films with a dielectric constant of less than 2.3 and a Young's modulus of 4 GPa were obtained by careful tuning of (1) the porogen to Aurora® X precursor gas flows during deposition and (2) the subsequent UV-cure time. Process optimization is monitored by Fourier Transform InfraRed and Elastic Recoil Detection analyses. Porogen-related groups (i.e. CH
2) are removed within the initial period of UV cure inducing thereby the formation of the porous network. However, the structural reorganization of the SiCO:H matrix, which leads to a mechanically stable film, requires a significantly longer time of UV curing for completion. Film overcuring causes the removal of CH
3 groups leading to loss of hydrophobicity, film densification and
k-value degradation. The optimized process results in films that show promising properties for future integration schemes.