Mask defect inspection using an extreme ultraviolet microscope

Abstract

A defect inspection technique on an extreme ultraviolet lithography mask is described. There are two kinds of defects, amplitude defects and phase defects due to the multilayer coating. The technique utilizes a microscope using the same 13.5 nm wavelength as the light used for exposure, and producing a magnified image of defects on a mask. Using this microscope, amplitude defects on practical masks and phase defects are observed. A phase defect was formed by a multilayer coated on a line pattern with a height of 5 nm and width of 90 nm on a glass substrate. Although the detected defect is made beforehand, it is detected by reflection of the light which penetrated inside of a multilayer. These results show that it is possible to detect the internal reflectivity distribution, without depending on surface perturbations.

Evaluation of protection schemes for extreme ultraviolet lithography (EUVL) masks against top–down aerosol flow

“…Extreme ultraviolet lithography (EUVL) is a strong candidate for the next lithography technology generation to achieve 32 nm nodes or smaller by utilizing a light of 13.4 nm wavelength (Gullikson, Tejnil, Liang, & Stivers, 2004;Hamamoto et al, 2005;Kim, Chang et al, 2006;Yan, He, Ma, & Orvek, 2006). Every EUVL mask must be assured of being free of particles prior to scanning exposure.…”

Experimental Investigations on Particle Contamination of Masks Without Protective Pellicles During Vibration or Shipping of Mask Carriers

“…Extreme ultraviolet lithography (EUVL), which is considered a strong candidate for the next lithography technology generation, utilizes radiation of very short wavelength of 13.4 nm to achieve 32-nm nodes or smaller [1], [2]. EUVL masks need to be protected against all particles larger than approximately 30 nm in the case of 32-nm node manufacturing [3].…”

Evaluation of extreme-ultraviolet lithography mask absorber pattern on multilayer phase defect using extreme-ultraviolet microscope

“…We demonstrated that a phase defect with a width of 90 nm and a depth of 5 nm was printable. 3 Furthermore, in 2007 our research group made smaller programed phase defects and demonstrated that the critical size for printable defects in a multilayer on a glass substrate was a width of 75 nm and a depth of 2 nm. 4 This result agrees well with the results of resist replication tests obtained with the microexposure tool ͑MET͒ at the Lawrence Berkeley National Laboratory ͑LBNL͒.…”