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Optical Lithography Modeling
Published in Bruce W. Smith, Kazuaki Suzuki, Microlithography, 2020
Chris A. Mack, John J. Biafore, Mark D. Smith
As the name implies, the photoacid generator forms a strong acid when exposed to deep-UV light. Ito and Willson first proposed the use of an arylonium salt [29], and triphenylsulfonium salts have been studied extensively as PAGs. The reaction of a common PAG is shown below:Ph|Ph−S+CF3COO−→hνCF3COOH+others|Ph
Lithography
Published in Andrew Sarangan, Nanofabrication, 2016
SU-8 is a negative-tone chemically amplified photoresist, developed by IBM, that cross-links and hardens when exposed to UV light followed by a heating step [59]. It is based on a chemical known as EPON resin SU-8. It is combined with a photoacid generator and is dissolved in an organic solvent such as cyclopentanone [60–62]. The quantity of the solvent determines the viscosity of the film and hence the thickness of the spin-coated film. Upon exposure to UV light, the photoacid generator produces an acid in the exposed areas of the film. During the heating step, this acid acts as a catalyst for the cross-linking reaction of the resin. The heating step also regenerates more acid in those areas through a chemical amplification process, resulting in a significantly higher sensitivity.
Innovative industrial technology starts with iodine
Published in Tatsuo Kaiho, Iodine Made Simple, 2017
A photoacid generator is a photosensitizer which generates acid by exposure to light. It is used as a photoresist (photosensitive composition) during the photolithography process in the production of semiconductor devices, printed circuit boards, and LCD (Liquid-Crystal Display) panels. The upper diagram shows the basic lithography process. The photoresist consists of either a negative type, where the pattern of the irradiated area remains, or a positive type where the irradiated area is removed after the development process.
Photoinduced movement: how photoirradiation induced the movements of matter
Published in Science and Technology of Advanced Materials, 2022
Tetsuo Yamaguchi, Makoto Ogawa
Both positive and negative phototaxis was observed in photoinduced transfer of nitrobenzene droplets in water, depending on surfactants surrounded the nitrobenzene droplet and photoacid/photobase in the water phase as shown in Figure 32 [489]. A nitrobenzene droplet being surrounded with 2-hexyldecanoic acid (HDA) showed negative phototaxis in an aqueous solution of a photobase, 6-methoxyquinoline (6MQ, Figure 32(Aa)), or a photoacid, 2-naphthol-6-sulfonate (2N6S, Figure 32(Ab)). A droplet being surrounded with HDA and C12-HPTS (shown in Figure 32(Ac)) showed positive phototaxis while a water/oil/water vesicle composed of didodecyldimethylammonium bromide (DDAB) and 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS, shown in Figure 32(d)) showed negative phototaxis. In the aqueous solution of the photobase (6MQ, Figure 32(a)), 6MQ captured a proton from HDA to form deprotonated HDA (DA−) and non-reacted HDA diffused to the light to cause Marangoni flow away from the light. As schematically shown in Figure 32(Ab), the droplet was surrounded with DA− initially. The DA− accepted proton from the photoacid (2N6S), consequently the DA− diffused to the irradiated region to make Marangoni flow away from the light. Photoinduced proton transfer from C12-HPTS to DA− made flow of deprotonated C12-HPTS and HDA away from the light (Figure 32(Ac)), which induced the Marangoni flow to the light. In the water/oil/water vesicle shown in Figure 32(Ad), protons generated from photoacid changed the ion strength in the irradiated area in the water phase, which caused flow in the water phases to the light, as the result, the vesicle moved away from the light.