Ms. Jing Cheng Profile

Jing Cheng

at Georgia Institute of Technology

SPIE Involvement:

Author

Publications (9)

Proceedings Article | 10 April 2013 Paper

Postiive tone resists based on network deploymerization of molecular resists

Richard Lawson, Jing Cheng, Ameneh Cheshmehkani, Laren Tolbert, Clifford Henderson

Proceedings Volume 8682, 868221 (2013) https://doi.org/10.1117/12.2021141

KEYWORDS: Polymers, Deep ultraviolet, Electron beam lithography, Molecules, Line edge roughness, Chemically amplified resists, Capillaries, Lithography, Extreme ultraviolet lithography, Optical lithography

Read Abstract +

Conventional chemically amplified resists have several issues that can potentially limit their capability for sub-40 nm imaging. One of the major issues at this size scale is that the mechanical strength of positive tone CARs limits the amount of stress they can withstand during development, rinse, and drying, thus leading to problems with pattern collapse due to the high capillary forces generated during drying. This problem is exasperated by the fact that linear polymers show dramatically reduced modulus at sub-50 nm features sizes. To improve on this problem, we have made a positive tone resist based on network depolymerization of molecular resists. The resist thermally cross-links after being spin cast into thin film form through reactions between vinyl ether groups and carboxylic acid groups. By cross-linking the resist to form a dense three dimensional polymer network, the mechanical strength of the resist is greatly improved compared to linear polymers. The network is depolymerized using an acid catalyzed reaction to create development contrast that allows for patterning of the resist via development in either aqueous base or organic solvent. One drawback of the current resist design is that the free carboxylic acids on the resist molecule appear to react in solution at room temperature with both the vinyl ether groups on adjacent molecules and with any added base quencher. These reactions cause reduced effectiveness of the base quencher and produce a noticeable resist shelf life problem. Despite these limitations, the material was used to compare the effect of development in aqueous base versus organic solvent. The resist formulated in this work showed a DUV sensitivity of 7 mJ/cm² and a contrast of 5.2 for development in either solvent or aqueous base. Under 100 keV e-beam imaging, the material showed 40 nm resolution for both development types. In standard 0.26 N TMAH, the dose-to-size was 84 μC/cm² with 3σ LER of 14.2 nm. Using methyl isobutyl ketone for organic solvent development, the dose-to-size was 104 μC/cm² with 3σ LER of 7.4 nm.

Proceedings Article | 5 April 2013 Paper

PS-b-PHOST as a high X block copolymers for directed self assembly: optimization of underlayer and solvent anneal processes

Nathan Jarnagin, Wei-Ming Yeh, Jing Cheng, Andrew Peters, Richard Lawson, Laren Tolbert, Clifford Henderson

Proceedings Volume 8680, 86801X (2013) https://doi.org/10.1117/12.2021420

KEYWORDS: Polymers, Annealing, Polymerization, Scanning electron microscopy, Picosecond phenomena, Thin films, Nitrogen, Directed self assembly, Polymer thin films, Glasses

Read Abstract +

Proceedings Article | 5 April 2013 Paper

PS-b-PHEMA: synthesis, characterization, and processing of a high X polymer for directed self-assembly lithography

Jing Cheng, Richard Lawson, Wei-Ming Yeh, Nathan Jarnagin, Laren Tolbert, Clifford Henderson

Proceedings Volume 8680, 86801W (2013) https://doi.org/10.1117/12.2021417

KEYWORDS: Polymers, Annealing, Lithography, FT-IR spectroscopy, Optical lithography, Etching, Magnesium, Solids, Polymerization, Directed self assembly

Read Abstract +

Proceedings Article | 5 April 2013 Paper

PS-b-PAA as a high X polymer for directed self-assembly: a study of solvent and thermal annealing processes for PS-b-PAA

Jing Cheng, Richard Lawson, Wei-Ming Yeh, Nathan Jarnagin, Laren Tolbert, Clifford Henderson

Proceedings Volume 8680, 86801V (2013) https://doi.org/10.1117/12.2021414

KEYWORDS: Annealing, Polymers, Scanning electron microscopy, Picosecond phenomena, Silicon, Semiconducting wafers, Etching, Polymerization, Solids, Directed self assembly

Read Abstract +

Proceedings Article | 16 April 2012 Paper

Investigation of high x block copolymers for directed self-asssembly: synthesis and characterization of PS-b-PHOST

Nathan Jarnagin, Jing Cheng, Andrew Peters, Wei-Ming Yeh, Richard Lawson, Laren Tolbert, Clifford Henderson

Proceedings Volume 8323, 832310 (2012) https://doi.org/10.1117/12.918081

KEYWORDS: Polymerization, Polymers, Optical lithography, Lithography, Scanning electron microscopy, Annealing, Molecular self-assembly, Directed self assembly, Glasses, FT-IR spectroscopy

Read Abstract +

Proceedings Article | 16 April 2012 Paper

Directed self-assembly of poly(styrene)-block-poly(acrylic acid) copolymers for sub-20nm pitch patterning

Jing Cheng, Richard Lawson, Wei-Ming Yeh, Nathan Jarnagin, Andrew Peters, Laren Tolbert, Clifford Henderson

Proceedings Volume 8323, 83232R (2012) https://doi.org/10.1117/12.918073

KEYWORDS: Polymers, Optical lithography, Lithography, Etching, Polymerization, Plasma etching, Annealing, Solids, Plasma, Directed self assembly

Read Abstract +

Directed self-assembly (DSA) of block copolymers is a promising technology for extending the patterning capability of current lithographic exposure tools. For example, production of sub-40 nm pitch features using 193nm exposure technologies is conceivably possible using DSA methods without relying on time consuming, challenging, and expensive multiple patterning schemes. Significant recent work has focused on demonstration of the ability to produce large areas of regular grating structures with low numbers of defects using self-assembly of poly(styrene)-b-poly(methyl methacrylate) copolymers (PS-b-PMMA). While these recent results are promising and have shown the ability to print pitches approaching 20 nm using DSA, the ability to advance to even smaller pitches will be dependent upon the ability to develop new block copolymers with higher χ values and the associated alignment and block removal processes required to achieve successful DSA with these new materials. This paper reports on work focused on identifying higher χ block copolymers and their associated DSA processes for sub-20 nm pitch patterning. In this work, DSA using polystyrene-b-polyacid materials has been explored. Specifically, it is shown that poly(styrene)-b-poly(acrylic acid) copolymers (PS-b-PAA) is one promising material for achieving substantially smaller pitch patterns than those possible with PS-b-PMMA while still utilizing simple hydrocarbon polymers. In fact, it is anticipated that much of the learning that has been done with the PS-b-PMMA system, such as development of highly selective plasma etch block removal procedures, can be directly leveraged or transferred to the PS-b-PAA system. Acetone vapor annealing of PS-b-PAA (M_w=16,000 g/mol with 50:50 mole ratio of PS:PAA) and its self-assembly into a lamellar morphology is demonstrated to generate a pattern pitch size (L₀) of 21 nm. The χ value for PS-b-PAA was estimated from fingerprint pattern pitch data to be approximately 0.18 which is roughly 4.5 times greater than the χ for PS-b-PMMA (_χPS-b-PMMA ~ 0.04).

Proceedings Article | 16 April 2011 Paper

Developing directly photodefinable substrate guiding layers for block copolymer directed self-assembly (DSA) patterning

Jing Cheng, Richard Lawson, Wei-Ming Yeh, Laren Tolbert, Clifford Henderson

Proceedings Volume 7972, 79722I (2011) https://doi.org/10.1117/12.894702

KEYWORDS: Polymers, Lithography, Electron beam lithography, Annealing, Optical lithography, Polymethylmethacrylate, Coating, Scanning electron microscopy, Deep ultraviolet, Directed self assembly

Read Abstract +

Directed self-assembly (DSA) of block copolymers has gained significant attention in recent years as a possible alternative for large area fabrication of future sub-30 nm lithographic patterns. To achieve this patterning, at least three critical pieces are needed: (1) a block copolymer with sufficient immiscibility of the two blocks to drive phase separation at the low molecular weights required to achieve such small phase domains, (2) a method for selectively removing one of the blocks after phase separation to achieve formation of a relief pattern, and (3) a method for producing the templated surfaces used to guide and register the phase separated patterns on the substrate of interest. Current methods for achieving the patterned substrate template, whether they are of chemoepitaxial or graphoepitaxial nature, are generally complex involving a large number of steps that are not easily applied to a variety of different substrate surfaces. For example, numerous substrates have been studied to provide neutral wettability to the styrene-methacrylate (PS-b- PMMA) block copolymers, such as random styrene-methacrylate copolymer films (PS-r-PMMA) or self-assembled monolayer (SAM) modified surfaces, which induce perpendicularly oriented morphologies for PS-b-PMMA self-assembly. In the case of chemical epitaxy processes, a layer of photoresist is generally then coated on such neutral substrate films and patterned to render commensurability to the periodicity of the PS-b-PMMA being used. The open (i.e. space) regions in the resist are then exposed to alter their chemistry, e.g. soft X-ray or oxygen plasma exposures have been used, to achieve hydrophilicity which should preferentially wet PMMA. Finally, the resist is stripped and the block copolymer is coated and assembled on the template surface. Obviously such multi-step processes would not be preferred if alternatives existed. As a step toward that goal of making DSA processes simpler, a photodefinable substrate film that can be used for PS-b-PMMA self-assembly has been developed in this work that is coated, exposed, and baked in a manner analogous to current optical photoresists. The polymer resin for this material is a form of protected poly(hydroxystyrene) that is cross-linkable. The new material is suitable for DSA processes using both solvent and thermal annealing methods. Results of PS-b-PMMA DSA on this new material will be discussed.

Proceedings Article | 31 March 2010 Paper

Non-traditional resist designs using molecular resists: positive tone cross-linked and non-chemically amplified molecular resists

Richard Lawson, David Noga, Jing Cheng, Laren Tolbert, Clifford Henderson

Proceedings Volume 7639, 76392F (2010) https://doi.org/10.1117/12.848419

KEYWORDS: Electron beam lithography, Deep ultraviolet, Polymers, Line edge roughness, Molecules, Solids, Optical lithography, FT-IR spectroscopy, Image resolution, Lithography

Read Abstract +

Proceedings Article | 26 March 2010 Paper

Aqueous and solvent developed negative-tone molecular resists

Richard Lawson, Jing Cheng, David Noga, Todd Younkin, Laren Tolbert, Clifford Henderson

Proceedings Volume 7639, 76390O (2010) https://doi.org/10.1117/12.848414

KEYWORDS: Molecules, Electron beam lithography, Deep ultraviolet, Line edge roughness, Polymers, Polymerization, Glasses, Dewetting, Optical lithography, Scanning electron microscopy

Read Abstract +

Showing 5 of 9 publications

View contact details

UPDATE YOUR PROFILE

Is this your profile? Update it now.

Sign into your SPIE.org account

Don’t have a profile and want one?

Create an account on SPIE.org

Keywords/Phrases

Search In:

Publication Years