Design and Synthesis of a Photoaromatization-Based Two-Stage Photobase Generator for Pitch Division Lithography

The synthesis of a two-stage photobase generator (PBG) based on photoinduced aromatization is described. This material was designed for use in resolution-enhanced photolithography. Computer modeling predicts that a delay in the onset of base generation can lead to improved image quality. This delay can be realized by a PBG that must undergo two sequential photoreactions for each molecule of base generated. Toward that end, latent PBGs were designed that are oxime esters of aliphatic acids, which undergo Norrish type II reactions to yield oxime esters of aromatic acids that are efficient PBGs

Additional file 1 of Difference in carcinogenicities of two different vapor grown carbon fibers with different physicochemical characteristics induced by intratracheal instillation in rats

Additional file 1. Supplementary figure and tables

Study of a Two-Stage Photobase Generator for Photolithography in Microelectronics

The investigation of the photochemistry of a two-stage photobase generator (PBG) is described. Absorption of a photon by a latent PBG (<b>1</b>) (first step) produces a PBG (<b>2</b>). Irradiation of <b>2</b> in the presence of water produces a base (second step). This two-photon sequence (<b>1</b> + <i>h</i>ν → <b>2</b> + <i>h</i>ν → base) is an important component in the design of photoresists for pitch division technology, a method that doubles the resolution of projection photolithography for the production of microelectronic chips. In the present system, the excitation of <b>1</b> results in a Norrish type II intramolecular hydrogen abstraction to generate a 1,4-biradiacal that undergoes cleavage to form <b>2</b> and acetophenone (Φ ∼ 0.04). In the second step, excitation of <b>2</b> causes cleavage of the oxime ester (Φ = 0.56) followed by base generation after reaction with water