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High performance Cu dual-damascene (DD) interconnects without process-induced damages are developed in porous SiOCH stacks with the effective dielectric constant ( e ) of 2.95, in which a carbon (C)-rich molecular-pore-stacking (MPS) SiOCH film ( = 2 5) is stacked directly on an oxygen (O)-rich porous SiOCH ( = 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 N 2 CF 4 O 2 gas mixture technique. Large hydrocarbons attached to hexagonal silica backbones in the MPS-SiOCH prevent the Si-CHx bonds from oxidation during O 2 -plasma ashing, suppressing the C-depleted 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.

A highly reliable, 65nm-node Cu interconnect technology has been developed with I 80nndZOOnm-pitched lines COnneCted through $IOOnm-vias. A porous SiOCH film (k=2.5) with sub-nanometer pores is introduced for the inter-metal dielectrics (IMD) on a non-porous, rigid SiOCH film (k=2.9) for the via-intra-line dielectrics (via-ILD). A key breakthrough is a special pore-seal technique, in which the trench-etched surface of the porous SiOCH is covered with an ultra-thin, low-k organic silica film (k=2.7), thus improving the lineto-line TDDB reliability of the narrow-pitched Cu lines.The filly-scaled-down, 65nm-node Cu interconnects with the porous-on-rigidSiOCH hybrid structure achieve excellent performance and reliability.

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Stress-induced voiding (SIV) is a serious problem in Cu dual-damascene interconnects (DDIs). The stress gradient under vias is the driving force of vacancy diffusion and void generation, therefore stress control in Cu-DDI is an important factor for suppressing SIV. In this study, the stress effect of upper Cu film on SIV in lower Cu lines is investigated, and the stress distribution in Cu-DDI is analyzed by finite element analysis. It is found that SIV in the lower Cu lines is strongly affected not only by the width of lower lines but also by the metallurgical properties of the Cu film in upper metals. Suppression of tensile stress in the via of the upper Cu film decreases the stress gradient in the lower line around the via, and eventually, the driving force of vacancy diffusion to the via bottom. Control of the metallurgical properties to suppress Cu creep during annealing is a key factor for decreasing SIV in lower Cu lines. High-temperature deposition of Cu film with a small coefficient of thermal expansion (CTE) is a solution to suppressing SIV failure in Cu-DDIs.

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The spherical β-calcium orthophosphate (β-Ca 3 (PO 4) 2 : β-TCP) agglomerates have been prepared by a spray-pyrolysis technique. The hollow spherical agglomerates were obtained by heating the spray-pyrolyzed powder at 900 for 10 min. The cylindrical specimen was fabricated mixing the calcium-phosphate paste (CPP) with 10-50 mass% β-TCP agglomerates, using malaxation liquid. The setting time of CPP specimen increased from 8.5 to 17 min with increasing amount of β-TCP from 10 to 50 mass%. The CPP specimens with β-TCP addition were immersed into the simulated body fluid (SBF) at 37±0.2 for various times. The compressive strengths of CPP specimens with β-TCP addition reached maxima, e.g., 42.8 MPa for 10 mass% β-TCP addition and 7.5 MPa for 50 mass% β-TCP addition, respectively, after the immersion of these specimens in SBF for 3-7 d. Crystalline phases of the CPP specimens after the immersion in SBF for 7 d were HAp and β-TCP. The total porosity of CPP specimen increased with increasing amount of β-TCP and attained 67.1% for 50 mass% β-TCP addition.