Diffusion Resistance of Low Temperature Chemical Vapor Deposition Dielectrics for Multiple Through Silicon Vias on Bumpless Wafer-on-Wafer Technology

Diffusion behavior of Cu in Cu through-silicon-vias (TSVs) fabricated using low-temperature plasma enhanced chemical vapor deposition (LT-PECVD) has been evaluated. Silicon oxynitride (SiON) barrier films were formed by LT-PECVD at 150 °C. Cu diffusion rate was found to increase with decreasing film...

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Bibliographic Details
Published inJapanese Journal of Applied Physics Vol. 50; no. 5; pp. 05ED02 - 05ED02-4
Main Authors Kitada, Hideki, Maeda, Nobuhide, Fujimoto, Koji, Mizushima, Yoriko, Nakata, Yoshihiro, Nakamura, Tomoji, Ohba, Takayuki
Format Journal Article
LanguageEnglish
Published The Japan Society of Applied Physics 01.05.2011
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Summary:Diffusion behavior of Cu in Cu through-silicon-vias (TSVs) fabricated using low-temperature plasma enhanced chemical vapor deposition (LT-PECVD) has been evaluated. Silicon oxynitride (SiON) barrier films were formed by LT-PECVD at 150 °C. Cu diffusion rate was found to increase with decreasing film density. The critical density and thickness for prevention of Cu diffusion into Si substrate have been estimated. In case of a film with density ${>}60$% of the bulk value and/or thickness ${>}100$ nm, no change of electrical resistance for stacked wafers containing TSVs was observed after 1000 cycles of thermal stress. According to above results, SiON film formed at 150 °C can be used for the TSV process without any degradation of electrical characteristics and reliability, enabling a reduction in total process temperature in the wafer-on-wafer technology.
Bibliography:Process flow of Dual-Damascene TSV interconnects for wafer staking. Bird's-eye view FIB-SEM image of stacked wafers and multiple TSVs on BEOL device. Cross-sectional TEM image (right side) of dielectric barrier at TSV sidewall. SIMS depth profile of Cu atoms after annealing at 400 °C for 10 h. Cu diffusion coefficient as a function of relative density. Critical thickness of dielectric layer as a function of relative density. Relationship of relative density and nitrogen ratio in the film analyzed by XPS analysis. Leakage current as a functional of electric field. Schematic diagram of the test structure for electrical measurement; (a) 65-nm Cu interconnects, (b) with multiple TSVs two wafer stack, and (c) isolated multiple TSVs without Cu interconnects. Via chain resistance cumulative failure distribution of Cu BEOL interconnects with and without Cu-TSVs.
ISSN:0021-4922
1347-4065
DOI:10.1143/JJAP.50.05ED02