Patterning method for low-k inter-metal dielectrics and associated semiconductor device

Abstract

Semiconductor fabrication techniques and associated semiconductor devices are provided in which conductive lines are separated by a low dielectric constant (low-k) material such as low-k film portions or air. An insulation layer such as SiO2 is etched to form raised structures. The structures are slimmed and a low-k material or sacrificial material is deposited. A further etching removes the material except for portions on sidewalls of the slimmed structures. A metal barrier layer and seed layer are then deposited, followed by a metal filler such as copper. Chemical mechanical polishing (CMP) removes portions of the metal above the raised structures, leaving only portions of the metal between the raised structures as spaced apart conductive lines. The sacrificial material can be removed by a thermal process, leaving air gaps. The raised structures provide strength while the air gap or other low-k material reduces capacitance.