Koichi Motoyama

BEOL process integration for the 7 nm technology node

A 36 nm pitch BEOL has been evaluated for the 7 nm technology node. EUV lithography was employed as a single-exposure patterning solution. For the first time, it is shown that excellent reliability results can be obtained for Cu interconnects at these small dimensions, by using a TaN/Ru barrier system and a selective Co cap.

Performance of ultrathin alternative diffusion barrier metals for next - Generation BEOL technologies, and their effects on reliability

In order to maximize Cu volume and reduce via resistance, barrier thickness reduction is a strong option. Alternative barriers for next-generation BEOL were evaluated in terms of barrier performance to O2 and Cu diffusion, and effects on reliability. A clear correlation of O2 barrier performance to electromigration was observed, suggesting that the key role of the barrier layer is to prevent oxidation of Cu or the Cu/barrier interface. Long-throw PVD-TaN showed superior O2 barrier performance to alternative metals such as PEALD-TaN, thermal ALD-TaN, -TaN(Mn) and - MnN and MnSiO3 self-forming barrier.

Hybridization of XRF/XPS and scatterometry for Cu CMP process control

This paper demonstrates the synergy between X-rays techniques and scatterometry, and the benefits to combine the data to improve the accuracy and precision for in-line metrology. Particular example is given to show that the hybridization addresses the challenges of aggressive patterning. In 10nm node back-end-of-line (BEOL) integration, we show that the hybridized data between scatterometry and simultaneous X-Ray Fluorescence (XRF) and X-ray Photoelectron Spectroscopy (XPS) provided the closest dimensional correlation to TEM results compared to the individual technique and CDSEM.

Comparison of key fine-line BEOL metallization schemes for beyond 7 nm node

For beyond 7 nm node BEOL, line resistance (R) is assessed among four metallization schemes: Ru; Co; Cu with TaN/Ru barrier, and Cu with through-cobalt self-forming barrier (tCoSFB) [1]. Line-R vs. linewidth of Cu fine wires with TaN/Ru barrier crosses over with barrier-less Ru and Co wires for beyond-7 nm node dimensions, whereas Cu with tCoSFB remains competitive, with the lowest line R for 7 nm and beyond. Our study suggests promise of this last scheme to meet requirements in line R and EM reliability.