2001 Fiscal Year Final Research Report Summary
Interface Control of Nanoporous/Organic Low-k Dielectrics and Metal Electrode
| Project/Area Number |
11450126
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Electronic materials/Electric materials
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| Research Institution | HIROSHIMA UNIVERSITY |
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Principal Investigator |
KIKKAWA Takamaro Research Center for Nanodevices and Systems, HIROSHIMA UNIVERSITY, Professor, ナノデバイス・システム研究センター, 教授 (60304458)
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| Co-Investigator(Kenkyū-buntansha) |
SHIBAHARA Kentaro Research Center for Nanodevices and Systems, HIROSHIMA UNIVERSITY, Associate Professor, ナノデバイス・システム研究センター, 助教授 (50274139)
YOKOYAMA Shin Research Center for Nanodevices and Systems, HIROSHIMA UNIVERSITY, Professor, ナノデバイス・システム研究センター, 教授 (80144880)
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| Project Period (FY) |
1999 – 2001
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| Keywords | Cu Ion / Porous MSQ / methylpolysilazane / methylsilsesquioxane / Low-k / ion-drift velocity / capacitor / Pool e-Frenkel current |
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| Research Abstract |
The purpose of this research is to investigate the interface reaction between porous low-k interlayer dielectric films derived from organic and inorganic precursors. As a consequence, a new interlayer dielectric film which can suppress Cu ion drift is formed. In order to study the mechanism of Cu ion drift in low-k dielectric films, capacitors with Cu electrodes were fabricated on low-k dielectric films and bias-temperature stress tests were carried out so that the flat band voltage shifts of the capacitors could be measured as ionic charges drifted under the electric fields.
Two kinds of precursors were prepared. One was a normal methylpolysilazane (Si_x(NH)_y CH_3) and the other was a porous methylpolysilazane in which a porogen was incorporated, where Si-NH bonds turned to Si-O-Si bonds, while Si-CH_3 bonds stayed constant. A porogen was remained in the film after the pre-bake and H_2O absorption steps and vanished after 400℃ cure step due to evaporation, resulting in the formation o
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f porous rnethylsilsesquioxane film.
Capacitance-Voltage characteristics of the normal and porous methylsilsesquioxane/SiO_2-substrate capacitors with Cu electrodes were measured before and after 200℃ and 0.1 MV/cm bias-temperature stress for 2 hours. The dielectric constants of the normal and porous rnethylsilsesquioxane films were 2.7 and 2.2, respectively. Flatvband voltage shifts after bias temperature stresses for the normal and porous methylsilsesquioxane/SiO_2/Si capacitors with Cu electrodes were 1.183 and 0.204 V, respectively. It is found that the less negative flatband voltage shift was observed for the porous methylsilsesquioxane film than for the normal film.
Results from Arrehnius plots of Cu ion drift velocity for porous and normal films indicated that Cu ion drift velocity in the porous film was lower than that in the normal film and the activation energies of Cu ion drift velocity were in the range of 1.0-1.1ev.
lt was found that porous methylsilsesquioxane (MSQ) derived from methylpolysilazane (MSZ) showed inprovement of Cu ion drift suppression by a order of magnitude. Furthermore, Cu ion drift caused defects in porous MSQ so that Poole-Frenkel leakage current increased, resulting in decrease of dielectric breakdown life time. Less
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