Chitosan as a Water-Developable 193 nm Photoresist for Green Photolithography

Abstract

The development of environmentally friendly materials and processes is a major issue that concerns all industrial sectors, including microelectronics. The aim of this study is to demonstrate the possibility of using chitosan-based photoresists for microelectronic applications on silicon by 193 nm photolithography. The photopatterning of chitosan films is demonstrated and analyzed by different spectroscopy and microscopy techniques. In particular, it is shown that 193 nm irradiation allows one to induce chain breaks that modify the solubility of chitosan in an aqueous developing solution, without denaturing the chitosan macromolecule chains. This mechanism allows one to obtain patterns, and it is shown that these patterns can be transferred by physical etching into silica. It is also demonstrated that the formulated resins are compatible with industrial spin-coating and exposure tools, which opens very interesting perspectives for these chitosan-based positive resins in a microelectronic context.

Chemically Amplified Molecular Glass Photoresist Regulated by 2-Aminoanthracene Additive for Electron Beam Lithography and Extreme Ultraviolet Lithography

“…After exposure, a new signal was observed at 288.8 eV, which was in accordance with the peak of −N−C�O. 31 In addition, a new peak at 401.6 eV was attributed to the formation of N−C bond after e-beam exposure as shown in Figure 4C. As for spectra of O 1s (Figure 4B), the peak shifts from 533.4 to 532.5 eV after exposure, which might be caused by the chemical reaction of 2-aminoanthracene with epoxide ring.…”

“…PAG is a photosensitive compound; in the post exposure baking (PEB) process, it will stimulate the reaction of the acid sensitive group on the main chain of the resin and generate new acid components. To improve lithography performance, the development of more advanced photoresist materials is significant. − Lawson’s team designed molecules with epoxy structure and used them for negative-tone photoresist. − After exposure, PAGs generate photoacid and catalyze the self-cross-linking reaction of the epoxy compounds, finally forming a dense network which drives the solubility switch. In addition, the huge cross-linked network can effectively improve the mechanical properties of the photoresist.…”

Chitosan as a water-based photoresist for DUV lithography

“…For both Mw, chitosan was prepared by deacetylation of chitin in alkaline medium, followed by a re-acetylation to reach a higher degree of acetylation (DA) > 35-37%, as summarized in Table 2. DUV irradiation induces the chain scissions of glycosidic linkages C−O−C, followed by the formation of hydroxyl groups [13]. The molar mass Mw of the chitosan chains decrease in the exposed zones, making it water-soluble during development step.…”

“…b). Additionally, patterns were properly transferred properly into silica based on CHF3 plasma etch (Figure4.c)[13].…”

Modular Synthesis of Phthalaldehyde Derivatives Enabling Access to Photoacid Generator-Bound Self-Immolative Polymer Resists with Next-Generation Photolithographic Properties

“…Development of new polymer-based resists has undergone a renaissance in the last 5 years due to the adoption of extreme ultraviolet (EUV) lithography as the premiere lithographic technology necessary for further reductions in transistor feature size. , The decade prior to 2015 was characterized by few new advances in resist chemistry as the lifespan of 193 nm lithography was extended using breakthroughs in immersion optics and phase-shifting masks that required minimal changes to previously established materials. − In contrast, the 13.5 nm wavelength used in EUV sources has transformed the exposure mechanism from well-understood selective photon absorption to indiscriminate ionization of a resist to generate secondary electrons. These secondary electrons move through the resist and are responsible for the ensuing chemical reactions.…”