node back end of the line yield evaluation on ultrahigh density interconnect structures using electron beam direct write lithography
Top views of line∕space with the process of reference: (a) after ebeam lithography: sensitivity to shot butting, and (b) after hard mask etch: line cut defect, with corresponding electrical measurements (c).
Description of different test structures used for evaluations: (a) Structure A or B into a real M1 environment with 40% of total writing area and (b) structure B exposed alone with an environment of total writing surface cloth to 0%.
Description of test structures A (a) and B (b) with same CD∕pitch .
Overall PW (a) and LER (b) evaluated on test structures A and B with different resist sensitivities.
PW (a) and LER (b) of patterns A and B evaluated with resists CR01P (POR) and CR01P-Tr1.
Comparison on structure B of PW (b) and of LER (b) values with 40% or 0% of writing area using different tested resists.
PW (a) and LER (b) vs the number of electrons per shot, evaluated for all resists on structures A and B with 40% and 0% of writing area.
Top view of serpentine-comb structure (CD ∕pitch ) after etch (a) and cumulative distribution of the measurements of resistance (b) and leakage current (c) on the wafer.
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