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dc.contributor.authorJung, Byungkien_US
dc.identifier.otherbibid: 8442212
dc.description.abstractMicrolithography and laser spike annealing (LSA) are key techniques that have enabled continued dimension scaling of transistors used in the semiconductor industry. As minimum feature sizes reach sub-20 nm scale in patterning, control of chemical reactions and their kinetics for a given lithographic material becomes critical for all thermally-activated processes. For example, current chemically amplified resist (CAR) systems require a post-exposure bake (PEB) where thermally-activated side-group cleavage reactions and acid-catalyst diffusion compete to control both pattern resolution and line edge definition. The use of LSA has been explored in this work as a potential PEB process, showing promise for multiple metrics of CAR system performance. This work explores the behavior of organic and small molecules under millisecond time frame laser-induced heating using far-infrared CO2 laser ([lamda] = 10.6 [MICRO SIGN]m) and nearinfrared laser diode ([lamda] = 980 nm) sources. To explore LSA heating of polymers, thin-film platinum resistors were fabricated and used to directly measure temperature profiles during LSA with high spatial and temporal resolution. Measured resistance changes were calibrated to absolute temperatures using melting points of silicon and thin-film gold dots. Effective substrate temperatures were obtained for dwell times ranging from 0.25 to 10 ms under both CO2 and diode laser irradiation. In addition, spatially dependent thermal profiles were obtained in sub-millisecond time frames at high spatial resolutions up to 20 [MICRO SIGN]m. LSA was used to heat thermally sensitive resist polymers at temperatures beyond their conventional limits in millisecond time frames. Due to the five orders of magnitude decrease in time from conventional heating duration, these organic systems extended their thermal stabilities by up to 800 ? C. Lithographic patterning using LSA as a PEB was explored under both deep UV (DUV) and extreme UV (EUV) exposures. Compared to conventional hot-plate PEB, high resolution (up to 50 nm lines/spaces) patterns were achieved at up to 30 % lower UV exposure doses (sensitivity) by accelerating the reaction kinetics at higher temperatures. Under these same conditions, the pattern roughness was reduced 25 % by minimizing the heating duration. The chemical reaction kinetics and pathways of a model resist system with a methyl adamantyl side-group were extensively studied over five orders of magnitude in heating duration, exhibiting non-Arrhenius behavior. The side-group cleavage kinetics were measured to follow first order at high temperatures associated with millisecond heating, while a more complex power law behavior was observed for seconds time frame heating near the polymer's glass transition. The responsible chemical change, affecting the active catalyst concentration during heating, was identified and mathematically modeled to explain the kinetic shift while providing fundamental understanding necessary for improving patterning performance. An alternative use of the laser-induced heating was demonstrated for controlling the pattern roughness by hardbaking fully developed resist profiles at peak temperatures between 295-450 ? C for 500 [MICRO SIGN]s. Due to polymer flow above the glass transition temperature, surface and edge smoothing up to 30 % with a <1 nm change in pattern dimension was observed. Laser spike annealing was also used to investigate the nucleation and growth kinetics of amorphous silicon (a-Si) at temperatures above 850 ? C for sub-millisecond time frames. An explosive crystallization of a-Si was observed containing a mix of fine-grained and large-grained polycrystalline phases, along with Si propagation in its liquid state to create a feather-like threads spanning over 100 [MICRO SIGN]m orthogonal to the scan direction. Results from this work highlight the utility of laser heating technique to characterize reaction kinetics over a wide range of temperature and time, while identifying key kinetic changes and the underlying mechanisms to gain fundamental understanding. Combined with existing methods to characterize material properties, LSA is a powerful technique for investigating reaction kinetics at high temperatures on millisecond time frames, not only for conventional semiconductor materials such as Si but also for thermally sensitive organic systems.en_US
dc.subjectLaser spike annealingen_US
dc.subjectChemical reaction kineticsen_US
dc.titleLaser-Induced Millisecond Heating Of Polymers And Small Molecules For Pattern Developmenten_US
dc.typedissertation or thesisen_US Science and Engineering Universityen_US of Philosophy D., Materials Science and Engineering
dc.contributor.chairThompson, Michael Olgaren_US
dc.contributor.committeeMemberOber, Christopher Kemperen_US
dc.contributor.committeeMemberDichtel, William Roberten_US

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