Paper PS-WeM10
Evaluation of Novel Etch Gas for BEOL Interconnect Pattern Transfer at 14nm and 22nm Technologies

Wednesday, October 31, 2012, 11:00 am, Room 25

As feature sizes continue to decrease, significant issues are found using high selectivity fluorocarbon gases to etch interconnect low-k dielectrics including low selectivity to organic masks, line wiggling and low-k damage. We have evaluated novel etch gases that enables the optimized fabrication of BEOL interconnects for 14nm and 22nm nodes. Compared to conventional fluorocarbon etch gases, experiments with a novel hydrofluorocarbon etch gas have shown a substantial increase in low-k dielectric etch selectivity to organic hard mask and improved selectivity to the capping layer. In addition, lower line-edge and line-width roughness values were observed. We investigate the etch behavior and selectivity between the low-k dielectric and organic hard mask, metal hard mask, and capping layer through optical emission spectroscopy and x-ray photoelectron spectroscopy. Etch performance is assessed for trench and via patterns and also full dual-damascene structures. Low-k damage is also investigated by post-etch HF treatment to measure critical dimension loss from dissolution of plasma-damaged dielectric. Finally, we propose a mechanism for high selectivity, low damage dielectric etch at sub-80nm pitch structures using rationally-designed novel etch gases.