TY - JOUR
T1 - Reducing extreme ultraviolet mask three-dimensional effects by alternative metal absorbers
AU - Philipsen, Vicky
AU - Luong, Kim Vu
AU - Souriau, Laurent
AU - Erdmann, Andreas
AU - Xu, Dongbo
AU - Evanschitzky, Peter
AU - Van De Kruijs, Robbert W.E.
AU - Edrisi, Arash
AU - Scholze, Frank
AU - Laubis, Christian
AU - Irmscher, Mathias
AU - Naasz, Sandra
AU - Reuter, Christian
AU - Hendrickx, Eric
PY - 2017/10/1
Y1 - 2017/10/1
N2 - Over the recent years, extreme ultraviolet (EUV) lithography has demonstrated the patterning of ever-shrinking feature sizes (enabling the N7 technology node and below), whereas the EUV mask has remained unaltered, using a 70-nm tantalum (Ta)-based absorber. This has led to experimentally observed mask three-dimensional (M3D) effects at the wafer level, which are induced by the interaction between the oblique incident EUV light and the patterned absorber with typical thickness values on the order of several wavelengths. We exploit the optical properties of the absorber material of the EUV mask as an M3D mitigation strategy. Using rigorous lithographic simulations, we screen potential single-element absorber materials for their optical properties and optimal thickness for minimum best focus variation through pitch at the wafer level. In addition, the M3D mitigation by absorber material is evaluated by process window comparison of foundry N5-specific logic clips. To validate the rigorous simulation predictions and test the processing feasibility of the alternative absorber materials, we have selected the candidate single elements nickel and cobalt for an experimental evaluation on wafer substrates. We present the film characterization as well as the first patterning tests of these single-element candidate absorber materials.
AB - Over the recent years, extreme ultraviolet (EUV) lithography has demonstrated the patterning of ever-shrinking feature sizes (enabling the N7 technology node and below), whereas the EUV mask has remained unaltered, using a 70-nm tantalum (Ta)-based absorber. This has led to experimentally observed mask three-dimensional (M3D) effects at the wafer level, which are induced by the interaction between the oblique incident EUV light and the patterned absorber with typical thickness values on the order of several wavelengths. We exploit the optical properties of the absorber material of the EUV mask as an M3D mitigation strategy. Using rigorous lithographic simulations, we screen potential single-element absorber materials for their optical properties and optimal thickness for minimum best focus variation through pitch at the wafer level. In addition, the M3D mitigation by absorber material is evaluated by process window comparison of foundry N5-specific logic clips. To validate the rigorous simulation predictions and test the processing feasibility of the alternative absorber materials, we have selected the candidate single elements nickel and cobalt for an experimental evaluation on wafer substrates. We present the film characterization as well as the first patterning tests of these single-element candidate absorber materials.
KW - absorber characterization
KW - extreme ultraviolet mask absorber
KW - mask three-dimensional effects
KW - rigorous mask three-dimensional lithography simulation
UR - http://www.scopus.com/inward/record.url?scp=85027002605&partnerID=8YFLogxK
U2 - 10.1117/1.JMM.16.4.041002
DO - 10.1117/1.JMM.16.4.041002
M3 - Article
AN - SCOPUS:85027002605
VL - 16
JO - Journal of micro/nanolithography, MEMS, and MOEMS
JF - Journal of micro/nanolithography, MEMS, and MOEMS
SN - 1932-5150
IS - 4
M1 - 041002
ER -