Title :
Comprehensive Chemistry Designs in Porous SiOCH Film Stacks and Plasma Etching Gases for Damageless Cu Interconnects in Advanced ULSI Devices
Author :
Hayashi, Yoshihiro ; Ohtake, Hiroto ; Kawahara, Jun ; Tada, Munehiro ; Saito, Shinobu ; Inoue, Naoya ; Ito, Fuminori ; Tagami, Masayoshi ; Ueki, Makoto ; Furutake, Naoya ; Takeuchi, Tsuneo ; Yamamoto, Hironori ; Abe, Mari
Author_Institution :
LSI Fundamental Res. Lab., NEC Electron. Corp., Kanagawa
Abstract :
High performance Cu dual-damascene (DD) interconnects without process-induced damages are developed in porous SiOCH stacks with the effective dielectric constant (keff) of 2.95, in which a carbon (C)-rich molecular-pore-stacking (MPS) SiOCH film (k = 2.5) is stacked directly on an oxygen (O)-rich porous SiOCH (k = 2.7) film. The novel etch-stopperless structure is obtained by comprehensive chemistry design of C/O ratios in the SiOCH stack and the etching plasma of an Ar/N2 /CF4 /O2 gas mixture technique. Large hydrocarbons attached to hexagonal silica backbones in the MPS-SiOCH prevent the Si-CHx bonds from oxidation during O2-plasma ashing, suppressing the C-de- pleted damage area at the DD sidewall. Combining multiresist mask process with immersion ArF photolithography, strictly controlled Cu DD interconnects with 180-nm pitched lines and 65-nm-diameter vias are obtained successfully, ready for the 300-mm fabrication.
Keywords :
ULSI; copper; gas mixtures; immersion lithography; integrated circuit interconnections; masks; permittivity; porous materials; silicon compounds; sputter etching; Cu; Cu dual-damascene interconnects; Cu interconnects; O2-plasma ashing; SiOCH; ULSI devices; chemistry designs; effective dielectric constant; etch-stopperless structure; gas mixture technique; hexagonal silica backbones; immersion ArF photolithography; molecular-pore-stacking; multiresist mask process; oxidation; plasma etching gases; porous SiOCH film stacks; size 300 mm; wavelength 180 nm; wavelength 65 nm; Argon; Dielectric constant; Etching; Gases; Hydrocarbons; Plasma applications; Plasma chemistry; Plasma devices; Silicon compounds; Ultra large scale integration; Interconnect; LSI; low-k dielectrics; plasma etching test;
Journal_Title :
Semiconductor Manufacturing, IEEE Transactions on
DOI :
10.1109/TSM.2008.2001225
