An ultralow-k dielectric with structured cylindrical pores is proposed for advanced CMOS interconnect technology. By using carbon nanotube (CNT) as a template, a porous dielectric with vertically-aligned cylindrical pores is formed on the Si₃N₄ etch stop layer and successfully integrated with the Cu damascene process. The fabricated cylindrical porous dielectric possesses an anisotropic dielectric property with a large inter-layer dielectric constant of 1.97 and a small intra-layer dielectric constant of 1.75, and a high elastic modulus of 15.7 GPa is maintained. The resulting dielectric constant is lower than the k-value of existing porous dielectrics with the same high mechanical strength. At the same time, the proposed low-k dielectric with cylindrical pores also has a highe...[ Read more ]

An ultralow-k dielectric with structured cylindrical pores is proposed for advanced CMOS interconnect technology. By using carbon nanotube (CNT) as a template, a porous dielectric with vertically-aligned cylindrical pores is formed on the Si₃N₄ etch stop layer and successfully integrated with the Cu damascene process. The fabricated cylindrical porous dielectric possesses an anisotropic dielectric property with a large inter-layer dielectric constant of 1.97 and a small intra-layer dielectric constant of 1.75, and a high elastic modulus of 15.7 GPa is maintained. The resulting dielectric constant is lower than the k-value of existing porous dielectrics with the same high mechanical strength. At the same time, the proposed low-k dielectric with cylindrical pores also has a higher thermal conductivity than the conventional low-k dielectric with spherical pores, which can effectively mitigate the temperature rise of the interconnect and improve the interconnect reliability. Due to the higher mechanical strength and thermal conductivity, the k-value of the cylindrical porous dielectric has more potential to be reduced compared to traditional porous dielectrics, which makes the proposed cylindrical porous dielectric a promising candidate to extend the scaling of low-k dielectrics. By using the proposed cylindrical porous dielectric as the interconnect dielectric, the interconnect delay and crosstalk can be effectively reduced compared with conventional spherical porous dielectrics, especially for the advanced interconnect technology of small pitches and large aspect ratios.