Schematic of plasma source.
Chemical structures of ArF photoresist films. (a) α-GBLMA/MAdMA/HAdMA, (b) OTDMA/MAdMA/DAdMA, and (c) OTDMA/MAdMA/CMAMA. DAdMA and CMAMA photoresists have norbornane structure in lactone group. DAdMA photoresist has hydroxyl group and CMAMA one has cyano group. Structures of protecting group are identical in three kinds of photoresist films.
Etching rates for each ArF photoresist film under chlorine plasma etching conditions. Error bars indicate standard deviations.
(Color online) SPM images of photoresist polymers after etching. Etching depth is 35 nm. Chlorine gas was used under all etching conditions. Height scale was 20 nm, and observed area was 400 × 400 nm. SPM images were measured by using contact mode. RMS roughness of each photoresist was calculated from SPM images.
FTIR spectra of initial ArF photoresist films: (a) CO region (1800 cm−1 = lactone group and 1730 cm−1 = ester group) and (b) CH region. Thin lines are deconvoluted peaks.
Ratios of decreased area to initial area at deconvoluted peaks. Decrease in ratio means that photoresist films are etched by plasma.
Chemical structures of ArF photoresist films. (a) OTDMA/MAdMA/HAdMA and (b) NLMA/MAdMA/HAdMA. Structures of protecting and polar groups are identical in two kinds of photoresist films.
Relationship between RMS roughness and ratio of CO bond dissociation. Dissociation of CO bonds is calculated from FTIR spectrum.
Monomer content in the polymers.
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