High chi polymer development for DSA applications using RAFT technology

Directed self-assembly (DSA) of block copolymers is proving to be an interesting and innovative method to make three-dimensional periodic, uniform patterns useful in a variety of microelectronics applications. Attributes critical to acceptable DSA performance of block copolymers include molecular weight uniformity, final purity, and reproducibility in all the steps involved in producing the polymers. Reversible Addition Fragmentation Chain Transfer (RAFT) polymerization technology enables the production of such materials provided that careful process monitoring and compositional homogeneity measurement systems are employed. It is uniquely suited to construction of multiblocks with components of widely divergent surface energies and functionality. We describe a high chi diblock system comprising partially fluorinated methacrylates and substituted styrenics. While special new polymer separation strategies involving controlled polymer particle assembly in liquid media are required for some monomer systems and molecular weight regimes, we have been able to demonstrate high yield and compositionally homogeneous diblocks of lamellar and cylindrical morphology with polydispersities < 1.1. During purification processes, these diblock materials undergo assembly processes in liquid media, and with appropriate controls, this allows for removal of soluble homopolymer contaminants. SAXS analyses of solid polymer samples provide estimates of lamellar d-spacing, and a good correlation with molecular weight is shown. This system will be described.

[1]  D. Sanders,et al.  Advances in patterning materials for 193 nm immersion lithography. , 2010, Chemical reviews.

[2]  J. Chiefari,et al.  Living free-radical polymerization by reversible addition - Fragmentation chain transfer: The RAFT process , 1998 .

[3]  Hiroshi Okazaki,et al.  Designing materials for advanced microelectronic patterning applications using controlled polymerization RAFT technology , 2011, Advanced Lithography.

[4]  Almar Postma,et al.  Living free radical polymerization with reversible addition : fragmentation chain transfer (the life of RAFT) , 2000 .

[5]  P. Friedel,et al.  Synthesis and phase‐separation behavior of α,ω‐difunctionalized diblock copolymers , 2011 .

[6]  Graeme Moad,et al.  Living Polymers by the Use of Trithiocarbonates as Reversible Addition−Fragmentation Chain Transfer (RAFT) Agents: ABA Triblock Copolymers by Radical Polymerization in Two Steps , 2000 .

[7]  Graeme Moad,et al.  Polymerization with living characteristics and polymers prepared therefrom , 1998 .

[8]  Graeme Moad,et al.  Living Radical Polymerization by the RAFT Process , 2005 .

[9]  Y. Brun,et al.  Characterization of synthetic copolymers by interaction polymer chromatography: Separation by microstructure. , 2010, Journal of separation science.

[10]  Graeme Moad,et al.  A more versatile route to block copolymers and other polymers of complex architecture by living radical polymerization : The RAFT process , 1999 .

[11]  W. Hinsberg,et al.  Block copolymer based nanostructures: materials, processes, and applications to electronics. , 2010, Chemical reviews.

[12]  I. Chin,et al.  On the microphase separation kinetics of symmetric diblock copolymers , 1994 .

[13]  Christopher Barner-Kowollik,et al.  Handbook of RAFT polymerization , 2008 .

[14]  K. Guarini,et al.  Polymer self assembly in semiconductor microelectronics , 2006 .