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Study of CD variation caused by the black border effect and out-of-band radiation in extreme ultraviolet lithography

[+] Author Affiliations
Weimin Gao

Synopsys Inc., Interleuvenlaan 15A, B-3001 Leuven, Belgium

IMEC, Kapeldreef 75, B-3001 Leuven, Belgium

Ardavan Niroomand

IMEC, Kapeldreef 75, B-3001 Leuven, Belgium

Micron Technology, Inc., 8000 S. Federal Way, P.O. Box 6, Boise, Idaho 83707-0006

Gian F. Lorusso

IMEC, Kapeldreef 75, B-3001 Leuven, Belgium

Robert Boone

Synopsys Inc., 1301 South Mopac Expressway, Austin, Texas 78746

Kevin Lucas

Synopsys Inc., 1301 South Mopac Expressway, Austin, Texas 78746

Wolfgang Demmerle

Synopsys GmbH, Karl-Hammerschmidt-Strasse 34, 85609 Munich, Germany

J. Micro/Nanolith. MEMS MOEMS. 13(2), 023005 (May 07, 2014). doi:10.1117/1.JMM.13.2.023005
History: Received September 25, 2013; Revised March 4, 2014; Accepted March 27, 2014
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Abstract.  Although extreme ultraviolet lithography (EUVL) remains a promising candidate for semiconductor device manufacturing of the 1× nm half pitch node and beyond, many technological burdens have to be overcome. The “field edge effect” in EUVL is one of them. The image border region of an EUV mask, also known as the “black border” (BB), reflects a few percent of the incident EUV light, resulting in a leakage of light into neighboring exposure fields, especially at the corner of the field where three adjacent exposures take place. This effect significantly impacts on critical dimension (CD) uniformity (CDU) across the exposure field. To avoid this phenomenon, a light-shielding border is introduced by etching away the entire absorber and multilayer at the image border region of the EUV mask. We present a method of modeling the field edge effect (also called the BB effect) by using rigorous lithography simulation with a calibrated resist model. An additional “flare level” at the field edge is introduced on top of the exposure tool flare map to account for the BB effect. The parameters in this model include the reflectivity and the width of the BB, which are mainly determining the leakage of EUV light and its influence range, respectively. Another parameter is the transition width which represents the half shadow effect of the reticle masking blades. By setting the corresponding parameters, the simulation results match well the experimental results obtained at the IMEC’s NXE:3100 EUV exposure tool. Moreover, these results indicate that the out-of-band (OoB) radiation also contributes to the CDU. Using simulation, we can also determine the OoB effect rigorously using the methodology of an “effective mask blank.” The study demonstrates that the impact of BB and OoB effects on CDU can be well predicted by simulations.

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© 2014 Society of Photo-Optical Instrumentation Engineers

Citation

Weimin Gao ; Ardavan Niroomand ; Gian F. Lorusso ; Robert Boone ; Kevin Lucas, et al.
"Study of CD variation caused by the black border effect and out-of-band radiation in extreme ultraviolet lithography", J. Micro/Nanolith. MEMS MOEMS. 13(2), 023005 (May 07, 2014). ; http://dx.doi.org/10.1117/1.JMM.13.2.023005


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