Benzyl methacrylate, positively

In this article we will describe two different types of positive electron-beam resists, which were briefly reported in our previous communications (2,3). One is the homopolymer or copolymer with methyl methacrylate and a-substituted benzyl methacrylate, which forms methacrylic acid units in the polymer chain on exposure to an electron-beam and can be developed by using an alkaline solution developer. In this case, the structural change in the side group of the polymer effectively alters the solubility properties of the exposed polymer, and excellent contrast between the exposed and unexposed areas is obtained. The other is a self developing polyaldehyde resist, which is depolymerized into a volatile monomer upon electron-beam exposure. The sensitivity was extremely high without using any sensitizer. 

Positive Electron-beam Resist of Poly (a-substituted Benzyl Methacrylate). The electron-beam resist behaviors of poly(a-substituted benzyl methacrylate)s are given in Table III. When the exposed resist films were developed with a mixture of MIBK and IPA, the sensitivities of these polymers were on the order of 10-4 C/cm2. When a dilute solution of sodium methoxide in methanol was used as a developer, the sensitivity was enhanced as compared with the former case, and increased with an increase in the bulkiness of the ester group of the polymer except for poly(a,a-diphenylethyl methacrylate). 

Figure 2. Conflict requirement between the sensitivity and dryetching durability in positive electron resists based on methacrylate polymers. Sputter etching rates were measured under the same conditions using CF, gas. Key 1, poly(p-methoxypheny1 methacrylate) 2, poly(phenyI methacrylate) (PPhMA) 3, poly(3-phenylpropyl meyhacrylate) 4, poly(benzyl methacrylate) 5, poly(p-methoxybenzyl methacrylate) 6, poly(p-fluorophenyl methacrylate 7, poly(trichloropheny1 methacrylate) 8, poly(methyl methacrylate) (PMMA) 9, poly(tert-buty1 methacrylate) 10, poly(ethyl methacrylate) 11, poly(isobutyl methacrylate) 12, poly(n-butyl methacrylate) (PnBMA) 13, poly(dimethyltetrafluoro methacrylate) (FPM) 14, poly(trichloromethyl methacrylate) (EBR-1) and 15, poly(hexafluorobutyl methacrylate) (FBM).

Table 1 shows the Q and e values and the monomer reactivity ratios rj and T2 for the radical copolymerization process. Since the monomer reactivity ratios between negatively birefringent methyl methacrylate (MMA) and positively birefringent 2,2,2-trifluoroethyl methacrylate (3FMA) and benzyl methacrylate (BzMA) are nearly equal to unity, these monomers can be randomly copolymerized, resulting in homogeneous and transparent copolymers. 

In agreement with the data on poly-a-olefins and poly-vinyl-ethers having the side chain asymmetric carbon atoms in the y-position with respect to the main chain, stereoregularity does not exert a remarkable influence on the rotatory power of poly-acrylates and poly-methacrylates. In fact, according to the quantitative data reported by H. Sobue, K. Matsuzaki, S. Nakano (135), and to the qualitative indications given by Liu, Szuty and Ullmann (64), concerning respectively poly-menthyl-meth-acrylate and poly-(l-methyl-benzyl)-methaciylate, the specific optical activity of the polymers does not vary by more than 30% when varying, within a wide interval, the isotactic triads content of the polymers (Table 18). 

Fe(II, III)-protoporphyrin-IX (heme, hemin) (7 a, b) with poly(L-lysine)17-22), poly(L-his-tidine)23, poly(y-benzyl-L-glutamate (with pendant imidazole)19 24, polyethylenimine19,22), poly(4-vinyl-pyridine) (also partly quartemized)19,22,25-3 32, poly(N- or 4(5)-vinylimidazoles) (partly substituted at position 2)19-25-33-37, water soluble imidazole modified polyphophazenes38, macroporous methyl methacrylate, with covalent bound imidazole39,40. ... 

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