Date of download: 7/11/2016 Copyright © 2016 SPIE. All rights reserved. In extreme ultraviolet lithography (EUVL), the leakage of the EUV light in the image border region from neighboring exposure fields, especially at the corner of the field where three adjacent exposures take place, results in significant CD variation. Figure Legend: From: Study of CD variation caused by the black border effect and out-of-band radiation in extreme ultraviolet lithography J. Micro/Nanolith. MEMS MOEMS. 2014;13(2): doi: /1.JMM

Date of download: 7/11/2016 Copyright © 2016 SPIE. All rights reserved. The CD variations diagonally across the four corners of the exposure field before and after the multilayer (ML) etch. Before the ML etch, more than 10-nm contact holes (CH) CD variation is seen at the corner of the field, while it significantly reduces to ∼ 1.5 nm after the ML etch. L: the upper- and lower-left side. R: the upper- and lower-right side. Figure Legend: From: Study of CD variation caused by the black border effect and out-of-band radiation in extreme ultraviolet lithography J. Micro/Nanolith. MEMS MOEMS. 2014;13(2): doi: /1.JMM

Date of download: 7/11/2016 Copyright © 2016 SPIE. All rights reserved. (a) Illustration of the mask cross section with the ML etched. The reticle masking (REMA) blades are placed close to the field edge. (b) The average CDs of the four corners before (open squares) and after (solid squares) the ML etch. Three regions can be defined for the CD variation. Figure Legend: From: Study of CD variation caused by the black border effect and out-of-band radiation in extreme ultraviolet lithography J. Micro/Nanolith. MEMS MOEMS. 2014;13(2): doi: /1.JMM

Date of download: 7/11/2016 Copyright © 2016 SPIE. All rights reserved. The principle of the black border (BB) model. The middle plot displays the total flare map, which consists by the flare map of the mask and an additional flare at the edge and corner of the field. The right plot is the zoom-in illustration of the corner. Three colors represent the three regions of the BB. A three-parameter sigmoid function is designed to model this local flare, which is added on top of the original flare map in the simulations. Figure Legend: From: Study of CD variation caused by the black border effect and out-of-band radiation in extreme ultraviolet lithography J. Micro/Nanolith. MEMS MOEMS. 2014;13(2): doi: /1.JMM

Date of download: 7/11/2016 Copyright © 2016 SPIE. All rights reserved. The simulations of the CD impact of the BB reflectivity. The resist CDs of 40-nm dense CHs are simulated for a 1×1-mm2 area at the corner of the field. The simulation conditions are NA=0.25; the conventional source σ=0.81; a and b=200 μm in the BB model with R=3.15% (a), 1.57% (b), and 0% (c). The results show that a residual BB reflectivity leads to a large CD variation at the edge and corner of the field: 3σ-CDU of 5.64 and 4.15 nm for R=3.15% and 1.57%, respectively. If this reflection could be removed (R=0%), the BB effect vanishes and no CD variation occurs. Figure Legend: From: Study of CD variation caused by the black border effect and out-of-band radiation in extreme ultraviolet lithography J. Micro/Nanolith. MEMS MOEMS. 2014;13(2): doi: /1.JMM

Date of download: 7/11/2016 Copyright © 2016 SPIE. All rights reserved. (a) The experimental method of determining the out-of-band (OoB) radiation by the E0 ratio. The first E0 was obtained with a ML blank (left graph). The second E0 was obtained with an aluminum-coated blank (right graph). The E0 ratio gives the OoB contribution of ∼ 1.8%. (b) The “effective blank” approach to model the OoB effect in EUVL. The first E0 is simulated with a ML blank. The second E0 is obtained by setting a 1.2% reflectivity in the BB which mimics the ∼ 1.8% OoB contribution. A good match of CH CDs is found between the simulations and experiments. Figure Legend: From: Study of CD variation caused by the black border effect and out-of-band radiation in extreme ultraviolet lithography J. Micro/Nanolith. MEMS MOEMS. 2014;13(2): doi: /1.JMM

Date of download: 7/11/2016 Copyright © 2016 SPIE. All rights reserved. The simulations of CH CD versus the wafer CD before and after the ML etch. The simulation conditions are the same as in the experiment described in Sec. 2. The calibrated resist (SEVR165) model is used in the simulation tool. In the case of before ML etch, the setting of b=200 μm, a=350 μm, and R=3% are chosen in the BB model and an agreement is seen between the simulations (red solid line) and experimental ones (void squares). A match can also been found between the brown solid line and the solid square symbols which represent the case of after ML etch. Figure Legend: From: Study of CD variation caused by the black border effect and out-of-band radiation in extreme ultraviolet lithography J. Micro/Nanolith. MEMS MOEMS. 2014;13(2): doi: /1.JMM

Date of download: 7/11/2016 Copyright © 2016 SPIE. All rights reserved. The simulations of the impact of the border width on CD uniformity (CDU). The resist CD is simulated for 40-nm dense CHs with 1×1-mm2 area at the corner. The simulation conditions are NA=0.25, the conventional source σ=0.81, a=200 μm, and R=1.26% in the BB model. The results show that every 100-μm accuracy of the positioning of the REMA blades leads to ∼ 1-nm CDU budget consumption under the assumed conditions. Figure Legend: From: Study of CD variation caused by the black border effect and out-of-band radiation in extreme ultraviolet lithography J. Micro/Nanolith. MEMS MOEMS. 2014;13(2): doi: /1.JMM