Organic Inorganic Photoresist And Laser Induced Heating Process For Next Generation Lithography
What technology will enable lithography to continue Moore's law beyond 10 nm node? Traditional photolithography, using a 193 nm wavelength and chemically amplified resist (CAR), is currently the workhorse in the semiconductor industry, but faces challenge of achieving required resolution and line width roughness (LWR). Extreme Ultraviolet Lithography (EUVL), using 13.5 nm light, is considered as the likely successor to 193 nm immersion lithography, but has been delayed for years due to both light source and resist materials challenges. Directed self-assembly (DSA) of block copolymers, as a bottom-up approach, has the potential for high resolution, but its process integration is completely different from conventional top-down lithography. All of these different techniques coexist as competing solutions, but also facing challenges at the same time. So how can we enable these technologies for the next generation lithography? This dissertation explores the materials used in these three main categories of lithography technologies (CAR, EUVL and DSA), providing unconventional approaches to address this question. Ultrafast and high temperature laser induced heating is utilized as a post exposure bake (PEB) method for chemically amplified photoresists. By studying the reaction and diffusion kinetics of photoresist systems during laser PEB, we have been able to correlate the apparent activation energies with pattern LWR for 193 nm photoresists. We found that the system with highest deprotection activation energy and lowest diffusion activation energy achieved 60% LWR reduction using laser PEB compared to conventional hotplate annealing. Laser annealing is also utilized for directed self-assembly of block copolymers. Polymer chain mobility is greatly increased by increasing temperature, allowing ordering within 5-20 ms before polymer decomposition can occur. Effects of laser power, dwell time, underlayer and graphoepitaxy were examined with long range order and alignment was achieved with 20 ms laser annealing. Ligand-stabilized metal oxide nanoparticles resist have shown extraordinary sensitivity for EUV lithography (4.2 mJ/cm2for the 22 nm features). This study suggests that ligands can be directly cleaved by UV radiation, which is accelerated in the presence of a photoacid generator (PAG). This implies that the ligand structures is important to resist performance. By systematically synthesizing and characterizing of nanoparticles with different ligands, we correlated the lithographic performance with ligand structures, offering the potential for future rational resist design.
Lithography; polymer; laser induced heating
Archer,Lynden A.; Thompson,Michael Olgar
Ph. D., Chemical Engineering
Doctor of Philosophy
dissertation or thesis