Next Generation Etch Technologies for EUV Patterning Era
As logic device node shrinks, various multiple patterning methods are developed to overcome technical limitations of lithography such as self-aligned double patterning (SADP), self-aligned quadruple patterning (SAQP), and litho-etch-litho-etch (LELE). Recently, extreme ultra-violet (EUV) lithography based patterning is one of the most promising candidates for the sub-7nm back end of line (BEOL) integration due to simple process flow and cost reduction. In spite of several advantages of EUV lithography, it still has restricted technical availability due to thin PR thickness and PR scums. Ultra-thin PR has been an issue for the post EUV process, and that is from low transmittance of EUV and PR collapse margin in EUV lithography process. The ultra-thin PR makes more difficult to solve residual scum between the lines to be etched. Especially, pattern bride defect lead to decrease open yield in BEOL metal line. When increasing descum amount for pattern bridge defect removal, notching defect caused by PR divot is increasing simultaneously due to the ultra-thin PR thickness. Therefore, the trade-off between resist line bridges and notching defect should be solved to improve EUV patterning process.
In this presentation, we address a cyclic deposition and etch technique as a solution for minimizing resist line bridges and breaks without any pattern notching defect.