Implementation of high-chi block copolymer materials in a mature process flow for directed self-assembly

With scaling of electronic devices, printing smaller structures on the chip has become more and more complex and costly. For a few years, directed self-assembly (DSA) has been considered as a viable and low-cost alternative and complementary patterning option for keeping the down-scaling alive in the coming years, while ensuring an economic benefit to the silicon industry. Instead of upgrading lithography tools and imaging materials, DSA process uses block copolymers that can spontaneously form 5 - 30 nm features to print fine patterns. Using PS-b-PMMA, a low-defectivity, stable baseline process flow, known as LiNe flow, has been established at imec, enabling line/space patterns with a pitch of 28 nm. However, further pitch scaling requires block copolymers with a higher chi interaction parameter. Your project will focus on screening potential high-chi materials, and developing an optimized process flow for high-chi DSA by using previous learning from our LiNe flow. Important figures of merit to assess the process performance are defectivity, roughness, repeatability, and cost of development. From this project, you will first get accustomed to advanced lithography tools in our 300 mm wafer production line environment. As you get familiar with the DSA process, the focus of your study will shift more towards defect and roughness inspection using state-of-the-art metrology tools and dedicated software.

[Generic DSA literature]

1. H.S. Philip-Wong et al., Block Copolymer Directed Self-Assembly Enables Sublithographic Patterning for Device Fabrication, Proc. of SPIE Vol. 8323, 832303, 2012. doi: 10.1117/12.9183122
2. C. M. Bates et al. Block copolymer lithography, Macromolecules, Vol. 47(1), 2014, doi: 10.1021/ma401762n

[Project specific literature]

1. H. Pathangi et al. Defect mitigation and root cause studies in 14 nm half-pitch chemo-epitaxy directed self-assembly LiNe flow, J. Micro/Nanolithogr, MEMS, MOEMS, Vol. 14(3), 2015, doi: 10.1117/1.JMM.14.3.031204
2. J. Doise et al. Strategies for increasing the rate of defect annihilation in the directed self-assembly of high-chi block copolymers, ACS Appl. Mater. Interfaces, Vol. 11(51), 2019, doi: 10.1021/acsami.9b17858