Pursuit of Lower Critical Dimensional Uniformity in EUV Resists

This paper describes Dow’s efforts toward improved Critical Dimensional Uniformity (CDU) in EUV resists. Many non-material related factors contribute to good CDU, such as aerial image quality. We have focused on fundamental resist properties like intrinsic dissolution contrast and we have found that the photo-decomposable base (PDB) concept can be successfully employed. With the use of a PDB, we can reduce CDU variation at lower exposure energies. For sensitivity, we have focused on more efficient EUV photon capture through increased EUV absorption, as well as more highly efficient PAGs for greater acid generating efficiency. The formulation concepts will be confirmed using Prolith stochastic resist modeling. For the 26nm hp contact holes, we observe excellent overall process window with over 280nm depth of focus for a 10% exposure latitude Process window. The 1σ CDU is 1.1 nm. We also obtain 20nm hp contact resolution in one of our new EUV resists.

[1]  P. S. McKinney,et al.  The electrochemical reduction of the triphenylsulfonium ion , 1968 .

[2]  Munirathna Padmanaban,et al.  Application of photodecomposable base concept to two-component deep-UV chemically amplified resists , 1996, Advanced Lithography.

[3]  Mark D. Smith,et al.  The lithographic impact of resist model parameters , 2004, SPIE Advanced Lithography.

[4]  Kim Dean,et al.  Improved lithographic performance for EUV resists based on polymers having a photoacid generator (PAG) in the backbone , 2005 .

[5]  David Van Steenwinckel,et al.  Lithographic importance of acid diffusion in chemically amplified resists , 2005, SPIE Advanced Lithography.

[6]  Yan Borodovsky,et al.  Marching to the beat of Moore's Law , 2006, SPIE Advanced Lithography.

[7]  Yayi Wei,et al.  Chemically amplified resists resolving 25 nm 1:1 line: space features with EUV lithography , 2007, SPIE Advanced Lithography.

[8]  Yayi Wei,et al.  Pathway to sub-30nm Resolution in EUV Lithography , 2007 .

[9]  S. Tagawa,et al.  Radiation Chemistry in Chemically Amplified Resists , 2010 .

[10]  C. Mack,et al.  Stochastic exposure kinetics of extreme ultraviolet photoresists: simulation study , 2011 .

[11]  J. Thackeray Materials challenges for sub-20-nm lithography , 2011 .

[12]  Su-Jin Kang,et al.  Impact of polymerization process on OOB on lithographic performance of a EUV resist , 2011, Advanced Lithography.

[13]  Yao-Ching Ku,et al.  Contrast improvement with balanced diffusion control of PAG and PDB , 2012, Other Conferences.

[14]  John J. Biafore,et al.  Application of stochastic modeling to resist optimization problems , 2012, Other Conferences.

[15]  Moshe Preil Factors that determine the optimum dose for sub-20nm resist systems: DUV, EUV, and e-beam options , 2012, Other Conferences.

[16]  Chao Fang,et al.  Optimization of a virtual EUV photoresist for the trade-off between throughput and CDU , 2013, Advanced Lithography.