Optimization of resolution-enhancement technology and dual-layer bottom-antireflective coatings in hypernumerical aperture lithography

Abstract

Extension of krypton fluoride excimer laser lithography to the fabrication of 0.18 μm devices Resolution-enhancement technique ͑RET͒ and dual-layer bottom-antireflective coatings ͑DL-BARC͒ must be adopted in hypernumerical aperture ͑NAϾ 1͒ lithography for a 45 nm half-pitch device. However, interactions of RET, polarization effect, and the resist process significantly impact on lithography performance. An in-house program and PROLITH 9.0 were employed to perform comprehensive optimization of RET and DL-BARC structures in order to improve pattern fidelity with a reasonable process window ͑PW͒. High-fidelity resist patterns are obtained when we employed optimum DL-BARC structures in conjunction with optimum RET. An alternating phase-shift mask and a conventional illumination is one kind of optimum combination of RET. An attenuated phase-shift mask and a cross-dipole illumination is the other one. Line-width changes are controlled within 4 nm. Sidewall angles are greater than 88°.

Option of resolution enhancement technology in advanced lithography

“…Then the optimal BARCs process does not always guarantee a fidelity of resist profiles. A program inhouse was developed to optimize multi-layer BARC structure by taking the impact of different masks, illuminations, polarization effects into account [5][6][7] . While option of RET has not been studied in details when DL-BARCs and polarization illumination are employed.…”