Electron beam inspection system based on the projection imaging electron microscope

Abstract. According to an International Technology Roadmap for Semiconductors (ITRS-2012) update, the sensitivity requirement for an extreme ultraviolet (EUV) mask pattern inspection system is to be less than 18 nm for half pitch (hp) 16-nm node devices. The inspection sensitivity of extrusion and intrusion defects on hp 64-nm line-andspace patterned EUV mask were investigated using simulated projection electron microscope (PEM) images. The obtained defect images showed that the optimization of current density and image processing techniques were essential for the detection of defects. Extrusion and intrusion defects 16 nm in size were detected on images formed by 3000 electrons per pixel. The landing energy also greatly influenced the defect detection efficiency. These influences were different for extrusion and intrusion defects. These results were in good agreement with experimentally obtained yield curves of the mask materials and the elevation angles of the defects. These results suggest that the PEM technique has a potential to detect 16-nm size defects on an hp 64-nm patterned EUV mask. © The Authors.Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

Section: Introductionmentioning

confidence: 99%

Extreme ultraviolet mask defect inspection with a half pitch 16-nm node using simulated projection electron microscope images

Iida¹,

Amano²,

Hirano³

et al. 2013

“…1 Improvement in image resolution is realized by using an electron beam as used in the SEM-type inspection systems, but because of the very small electronbeam spot size used in such systems, it takes too much time for inspection. Therefore, we have been developing a projection electron microscope (PEM) 2,3 for pattern inspection and have evaluated its feasibility. [4][5][6][7] In order to accelerate this development program, the optimal inspection condition was investigated by using a computer simulation.…”

Section: Introductionmentioning

confidence: 99%

Impact of B₄C capping layer for extreme ultraviolet mask on the sensitivity of patterned mask inspection using a projection electron microscope

Iida¹,

Hirano²,

Amano³

et al. 2014

Abstract. The inspection sensitivity of a patterned extreme ultraviolet mask with B 4 C-capped multilayer (ML) was investigated using a simulated projection electron microscope (PEM) image. Extrusion and intrusion defects with 16-nm size were detected with their intensity of >10 times the standard deviation of the background level on a half-pitch 64-nm line-and-space pattern. The defect detection sensitivity in this case was higher than that of a Ru-capped ML sample and has a potential to meet the requirement for beyond 16-nm node generation from the standpoint of patterned mask inspection using the PEM technique. These results indicate that the B 4 C capping layer, besides its good durability, has an advantage for high sensitivity of patterned mask inspection. The optimal condition of the incident beam energy was found to be 500 and 1,000 eV for the samples of B 4 C-capped ML and B 4 C-buffered Ru-capped ML, respectively. The sensitivity of defect detection was strongly affected by the difference of secondary electron emission coefficients (SEECs) between the absorber layer and capping layer. However, the small incident beam energy was found to be preferable when the SEEC difference was relatively high. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

“…An electron beam (EB) inspection system has an advantage of its high image resolution. The EB inspection system, however, does also have the disadvantage of its lower throughput, but that can be overcome by using a projectiontype microscope with wider illumination beam, [2][3][4] or by using multibeam scanning electron microscope (SEM) type inspection systems. [5][6][7][8] In the pattern inspection system, the signal-to-noise ratio (SNR) is another critical parameter as it affects the defect detection sensitivity and minimizes false defect detection.…”

mentioning

confidence: 99%

“…10 The projection-type microscope is free from the space charge limit because of its wider illumination beam. 2 Moreover, any resolution degradation due to the aberration of imaging electron optics (EO) can be improved by the aberration correction systems.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Investigation of defect detectability for extreme ultraviolet patterned mask using two types of high-throughput electron-beam inspection systems

Iida¹,

Hirano²,

Amano³

et al. 2016

"Investigation of defect detectability for extreme ultraviolet patterned mask using two types of high-throughput electron-beam inspection systems," J. Abstract. Defect detectability using electron-beam (EB) inspection for an extreme ultraviolet (EUV) mask was investigated by comparing a projection electron microscope (PEM) and a scanning electron microscope (SEM) inspection system. The detectability with EB does not coincide with the printability data because the contrasts of the EUV aerial image and EB image for EUV mask are reversed. The 16-nm-sized defect on a half-pitch 64-nm line and space (L/S) pattern is detected even when the line edge roughness is taken into account in both PEM and SEM inspections by applying a special algorithm for image processing. The required and robust inspection conditions, such as the number of electrons per pixel and pixel size (resolution), were examined for an SEM inspection system. The throughput of the PEM inspection system corresponds to that of the multibeam SEM one with 200 to 1850 beams. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.