For development and improvement of chemically amplified resists, the mechanisms of acid-generation reactions and the matrix effects were studied by using a pulse radiolysis technique. Ionic and nonionic acid generators act as electron scavengers when irradiated with an ionizing radiation in methanol solutions, resulting in the formation of Br4nsted acids. Rate constants for the reactions of the acid generators with a solvated electron have been detennined. The rate constants of the onium salts were in the range of (1.6-2.7) x 1010 M' s. The nonionic acid generators were also found to be highly reactive to the solvated electron. Regardless of the structures and the polarities, the acid generators contribute to the acid generation by scavenging the solvated electron with the rates close to the diffusion-controlled limit. The reaction of acid generator with electrons trapped by base polymer was clarified. It would appear that electron scavenging reaction by acid generator in chemically amplified EB resist have two processes, and both process contribute to acid generation mechanism.
Terpolymers consisting of ␥-butyrolactone-2-yl methacrylate, 2-methyl-2-adamantyl methacrylate, and 1-methyl-1-͑6-methyl-7-oxabicyclo͓4,1,0͔hept-3-yl͒ethyl methacrylate were prepared by the reversible addition-fragmentation chain transfer polymerization technique. The molecular weight distribution of the polymers was 1.29-1.39. Although the polymers have epoxy units and cross-linking of the polymer occurred during prebake treatment, they worked as a highly sensitive positive-tone resist. The cross-linking efficiency of the resist was dependent on the type of amines used as a quencher. The line edge roughness values were dependent on the prebake temperature.
A novel method was developed to fabricate corrugation for a λ/4-shifted distributed feedback (DFB) laser. Mechanically ruled grating patterns were transferred photolithographically to the surface of an InP substrate. The resultant λ/4-shifted DFB laser operated in a single longitudinal mode at the Bragg wavelength.
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