Photoresist Latent and Developer Images as Probed by Neutron Reflectivity Methods

Photoresist materials enable the fabrication of advanced integrated circuits with ever-decreasing feature sizes. As next-generation light sources are developed, using extreme ultraviolet light of wavelength 13.5 nm, these highly tuned formulations must meet strict image-fidelity criteria to maintain the expected performance gains from decreases in feature size. However, polymer photoresists appear to be reaching resolution limits and advancements in measurements of the in situ formed solid/solid and solid/liquid interface is necessary. This Review focuses on the chemical and physical structure of chemically amplified photoresists at the lithographic feature edge at length scales between 1 nm and 100 nm. Neutron reflectivity measurements provide insight into the nanometer-scale composition profiling of the chemical latent image at an ideal lithographic line-edge that separates optical resolution effects from materials processing effects. Four generations of advanced photoresist formulations were examined over the course of seven years to quantify photoresist/photoacid and photoresist/developer interactions on the fidelity of lithographic features. The outcome of these measurements complement traditional resist design criteria by providing the effects of the impacts of the photoresist and processing on the feature fidelity. These physical relations are also described in the context of novel resist architectures under consideration for next-generation photolithography with extreme-ultraviolet radiation.

[1]  R. Ayothi,et al.  Sub-50 nm feature sizes using positive tone molecular glass resists for EUV lithography , 2006 .

[2]  S. Satija,et al.  Water immersion of model photoresists: interfacial influences on water concentration and surface morphology , 2005 .

[3]  S. Satija,et al.  Direct measurement of the spatial extent of the in situ developed latent image by neutron reflectivity , 2007 .

[4]  Arnost Reiser,et al.  The dissolution of novolak in aqueous alkali , 1989 .

[5]  Minoru Toriumi,et al.  Image contrast slope and line edge roughness of chemically amplified resists for postoptical lithography , 2007 .

[6]  K. Gonsalves,et al.  Preparation of a Photoacid Generating Monomer and Its Application in Lithography , 2001 .

[7]  Mingxing Wang,et al.  Novel anionic photoacid generators (PAGs) and corresponding PAG bound polymers for sub-50 nm EUV lithography , 2007 .

[8]  Wen-li Wu,et al.  Effect of copolymer composition on acid-catalyzed deprotection reaction kinetics in model photoresists , 2006 .

[9]  Jin Baek Kim,et al.  A positive-working alkaline developable photoresist based on partially tert-Boc-protected calix[4]resorcinarene and a photoacid generator , 2002 .

[10]  K. Lavery,et al.  Thin-film solid-state proton NMR measurements using a synthetic mica substrate: polymer blends. , 2009, Journal of magnetic resonance.

[11]  C. Willson,et al.  Approaches to the Design of Radiation‐Sensitive Polymeric Imaging Systems with Improved Sensitivity and Resolution , 1986 .

[12]  Y. Yoneda,et al.  Anomalous Surface Reflection of X Rays , 1963 .

[13]  Taku Hirayama,et al.  New Photoresist Based on Amorphous Low Molecular Weight Polyphenols , 2004 .

[14]  Wen-li Wu,et al.  Influence of base additives on the reaction diffusion front of model chemically amplified photoresists , 2007 .

[15]  Hiroaki Fujishima,et al.  Comparison of acrylate and methacrylate resin system in ArF lithography , 2000, Advanced Lithography.

[16]  Sergei V. Postnikov,et al.  Study of resolution limits due to intrinsic bias in chemically amplified photoresists , 1999 .

[17]  Martha I. Sanchez,et al.  Influence of resist components on image blur in a patterned positive-tone chemically amplified photoresist , 2002 .

[18]  M. Wormington.  Evidence for grading at polished surfaces from grazing-incidence X-ray scattering , 1996 .

[19]  W. Hinsberg,et al.  Characterization of Reactive Dissolution and Swelling of Polymer Films Using a Quartz Crystal Microbalance and Visible and Infrared Reflectance Spectroscopy , 2005 .

[20]  G. Wallraff,et al.  Determination of coupled acid catalysis-diffusion processes in a positive-tone chemically amplified photoresist , 2000 .

[21]  V. Prabhu.  Counterion structure and dynamics in polyelectrolyte solutions , 2005 .

[22]  Hiroshi Ito.  Chemical amplification resists: Inception, implementation in device manufacture, and new developments , 2003 .

[23]  Gregory M. Wallraff,et al.  IBM-JSR 193-nm negative tone resist: polymer design, material properties, and lithographic performance , 2004, SPIE Advanced Lithography.

[24]  Harry J. Levinson,et al.  Line edge roughness and intrinsic bias for two methacrylate polymer resist systems , 2006 .

[25]  Martha I. Sanchez,et al.  Acid–base reactions in a positive tone chemically amplified photoresist and their effect on imaging , 2004 .

[26]  Wen-li Wu,et al.  Measurements of the Reaction-Diffusion Front of Model Chemically Amplified Photoresists with Varying Photoacid Size | , 2006 .

[27]  Sirota,et al.  X-ray and neutron scattering from rough surfaces. , 1988, Physical review. B, Condensed matter.

[29]  W. Hinsberg,et al.  Lithographic Imaging Techniques for the Formation of Nanoscopic Features. , 1999, Chemical reviews.

[30]  Wen-li Wu,et al.  Characterization of Compositional Heterogeneity in Chemically Amplified Photoresist Polymer Thin Films with Infrared Spectroscopy , 2007 .

[31]  G. Schmid,et al.  Spatial distribution of reaction products in positive tone chemically amplified resists , 2002 .

[32]  Hiroshi Ito,et al.  Reactive dissolution kinetics of lithographic copolymers , 2004, SPIE Advanced Lithography.

[33]  C. Grant Willson,et al.  Acid catalyst mobility in resist resins , 2002 .

[34]  Nelson Felix,et al.  Dissolution phenomena of phenolic molecular glass photoresist films in supercritical CO2 , 2007 .

[35]  Gregory Breyta,et al.  Effect of resist components on image spreading during postexposure bake of chemically amplified resists , 2000, Advanced Lithography.

[36]  L. Nevot,et al.  Characterization of surfaces by grazing X-ray reflection: Application to the study of the polishing of various silicate glasses , 1991 .

[37]  Hikaru Momose,et al.  Effect of end group structures of methacrylate polymers on ArF photoresist performances , 2001, SPIE Advanced Lithography.

[38]  Vivek M. Prabhu,et al.  Proton NMR Determination of Miscibility in a Bulk Model Photoresist System: Poly(4-hydroxystyrene) and the Photoacid Generator, Di(tert-butylphenyl)Iodonium Perfluorooctanesulfonate , 2004 .

[39]  L. Névot,et al.  Caractérisation des surfaces par réflexion rasante de rayons X. Application à l'étude du polissage de quelques verres silicates , 1980 .

[40]  Martha I. Sanchez,et al.  Chemical and physical aspects of the post-exposure baking process used for positive-tone chemically amplified resists , 2001, IBM J. Res. Dev..

[41]  Wen-Li Wu.  Off‐specular reflection from flat interfaces with density or compositional fluctuations , 1993 .

[42]  M. Stewart,et al.  Line edge roughness in chemically amplified resist: Speculation, simulation and application , 2005 .

[43]  Bruno M. La Fontaine,et al.  Characterization of line-edge roughness in photoresist using an image fading technique , 2004, SPIE Advanced Lithography.

[44]  Nelson Felix,et al.  Solid state NMR investigation of photoresist molecular glasses including blend behavior with a photoacid generator , 2009 .

[45]  S. Satija,et al.  Lateral length scales of latent image roughness as determined by off-specular neutron reflectivity , 2008 .

[46]  Wen-li Wu,et al.  Exposure dose effects on the reaction-diffusion process in model extreme ultraviolet photoresists , 2006 .

[47]  Mingxing Wang,et al.  Incorporation of ionic photoacid generator (PAG) and base quencher into the resist polymer main chain for sub-50 nm resolution patterning , 2008 .

[48]  Xuelong Shi.  Effect of Coulomb interaction and pKa on acid diffusion in chemically amplified resists , 1999 .

[49]  Martha I. Sanchez,et al.  Deep-ultraviolet interferometric lithography as a tool for assessment of chemically amplified photoresist performance , 1998 .

[50]  Yasin Ekinci,et al.  Photon-beam lithography reaches 12.5nm half-pitch resolution , 2007 .

[51]  R. Dammel.  Diazonaphthoquinone-based resists , 1993 .

[52]  Hiroo Kinoshita,et al.  Optimization of Photoacid Generator in Photoacid Generation-Bonded Resist , 2008 .

[53]  C. Willson,et al.  Chemical amplification in the design of dry developing resist materials , 1983 .

[54]  Seung Wook Chang,et al.  Molecular glass photoresists for advanced lithography , 2006 .

[55]  J A Hoffnagle,et al.  Method of measuring the spatial resolution of a photoresist. , 2002, Optics letters.

[56]  Hiroshi Ito,et al.  Direct measurement of the counterion distribution within swollen polyelectrolyte films. , 2005, Langmuir : the ACS journal of surfaces and colloids.

[57]  Peng Zhang,et al.  Formulated surface conditioners to enhance the non-collapse window and maintain defect control: a bi-functional approach for sub-100-nm lithography , 2006, SPIE Advanced Lithography.

[58]  Wen-Li Wu,et al.  Direct Measurement of the Reaction Front in Chemically Amplified Photoresists , 2002, Science.

[59]  Nelson Felix,et al.  Study of the Structure−Properties Relationship of Phenolic Molecular Glass Resists for Next Generation Photolithography , 2008 .

[60]  Wen-Li Wu,et al.  Effect of deprotection extent on swelling and dissolution regimes of thin polymer films. , 2006, Langmuir : the ACS journal of surfaces and colloids.

[61]  Hiroshi Ito.  Chemical amplification resists for microlithography , 2005 .

[62]  T. Baumbach,et al.  Nonspecular x-ray reflection from rough multilayers. , 1994, Physical review. B, Condensed matter.

[63]  Martha I. Sanchez,et al.  Kinetic Model for Positive Tone Resist Dissolution and Roughening , 2002 .

[64]  Lewis W. Flanagin,et al.  The Mechanism of Phenolic Polymer Dissolution: A New Perspective , 1997 .

[65]  Andrew Jamieson,et al.  Using mesoscale simulation to explore photoresist line edge roughness , 2005, SPIE Advanced Lithography.

[66]  Yoshikazu Yamaguchi,et al.  Influence of Acid Diffusion Length on Line Edge Roughness in KrF Photoresists , 2004 .

[67]  Gregory M. Wallraff,et al.  Thermal and acid‐catalyzed deprotection kinetics in candidate deep ultraviolet resist materials , 1994 .

[68]  C. Grant Willson,et al.  Study of acid transport using IR spectroscopy and SEM , 2000, Advanced Lithography.

[69]  Wen-Li Wu,et al.  Polyelectrolyte effects in model photoresist developer solutions , 2003 .