Imaging characteristics and specification of mask mean-to-target and mask uniformity according to polarization status

Abstract

Maximum exposure latitude ͑EL͒, mask error enhancement factor ͑MEEF͒, and intrafield critical dimension ͑CD͒ uniformity are compared in TE and unpolarized ͑UNP͒ light. An ArF dry scanner with 0.85 numerical aperture and dipole illumination with inner and outer sigmas of 0.93 and 0.69 is used. 63 and 73 nm nodes are chosen which have 126 and 146 nm pitch sizes and Target CDs of 63 and 73 nm. TE shows 56% and 10% larger maximum EL than UNP for 63 and 73 nm nodes, respectively. TE shows 56% increased IFU compared with UNP at the 63 nm node. MEEFs are 3.4 and 4.1 for TE and UNP light at the 63 nm node, respectively. MEEFs of 1.4 and 1.5 are observed for TE and UNP light at the 73 nm node. Mask mean-to-target ͑MTT͒ and uniformity specifications are compared according to polarization status. For the 63 nm node, specifications of mask MTTs are ±1.28 and ±1.28 nm and the mask uniformities are 1.43 and 1.18 nm for TE and UNP light, respectively. For the 73 nm node, ±2.62 and ±2.43 nm of the mask MTT specifications are obtained with mask uniformities of 4.04 and 3.77 nm at TE and UNP light. TE light shows 28% and 11% larger MTT and uniformity specification areas than UNP light for 63 and 73 nm nodes.

Study of Mask Proximity Impact on Mask Mean-to-Target Specification

“…The NA of the exposure tool can be increased further using a highrefractive-index liquid. This immersion exposure tool introduces the hyper NA regime in which polarization 2) and the three-dimensional mask topography effect 3) appear to have significant effects on imaging results. The analysis to comprehend hyper NA imaging results requires complicated and rigorous approaches, which makes it difficult to understand the imaging mechanism through insight.…”