EUV patterned mask inspection system using a projection electron microscope technique

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Abstract. Patterned mask inspection for an etched multilayer (ML) extreme ultraviolet mask was investigated. In order to optimize the mask structure from the standpoint of a pattern inspection the mask structure not only from the standpoint of a pattern inspection by using a projection electron microscope but also by using a projection electron microscope but also by considering the other fabrication processes using electron beam techniques such as critical dimension metrology and mask repair, we employed a conductive layer between the ML and substrate. By measuring the secondary electron emission coefficients of the candidate materials for the conductive layer, we evaluated the image contrast and the influence of the charging effect. In the cases of 40-pair ML, 16-nm-sized extrusion and intrusion defects were found to be detectable more than 10 sigma in half pitch 44, 40, and 32 nm line-and-space patterns. Reducing 40-pair ML to 20-pair ML degraded the image contrast and the defect detectability. However, by selecting B 4 C as a conductive layer, 16-nm-sized defects and etching residues remained detectable. The 16-nm-sized defects were also detected after the etched part was refilled with Si. A double-layer structure with 2.5-nm-thick B 4 C on metal film used as a conductive layer was found to have sufficient conductivity and also was found to be free from the surface charging effect and influence of native oxide. © 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: Methodsmentioning

confidence: 99%

Pattern inspection of etched multilayer extreme ultraviolet mask

Iida¹,

Hirano²,

Amano³

et al. 2016

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“…Image processing operations were applied to the simulated image to enhance the detect signal intensities. 6,9 The detailed simulation conditions were described earlier. shows the experimental SEEC difference (which is calculated by subtracting the SEEC of these MLs from that of the absorber layer) as a function of incident beam energy.…”

Section: Methodsmentioning

confidence: 99%

“…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. [8][9][10][11] We already reported that 16-nm-sized defect on hp 64-nm mask pattern was detectable with a 10-times higher signal intensity than that of the standard deviation of the background intensity level by using the PEM technique when the Ru capped multilayer (ML) was used in EUV mask, 9 and the simulated detectability was found to be in good agreement with experimental results.…”

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

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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.

“…In order to enhance the defect signal intensities, different types of image processing operations for PEM and SEM images were applied to the simulated images. 9,17 The EUV aerial image and the wafer printability of the mask defects were simulated using a LAIPH™ defect printability simulator (Luminescent Technologies Inc.). 26 For a typical defect type, we focused on edge extrusion and edge intrusion, and we evaluated the printability with the printed space-width difference on a wafer.…”

Section: Methodsmentioning

confidence: 99%

“…9,[14][15][16][17][18][19][20][21][22][23][24] In order to accelerate this development program, the optimal inspection condition and the analysis of PEM image were investigated by using a computer simulation. 9,[18][19][20][21][22][23] We had already reported that a ≥12-nm-sized defect on hp 64-nm mask pattern was detectable by the developed PEM, 24 and that the detectability is in good agreement with the simulation results.…”

mentioning

confidence: 99%

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

Self Cite

"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.