We examined the solubility of C]0 derivatives and then investigated the resist characteristics after preparing nanocomposite resists with ZEP using the derivatives.
Table 9.4 summarizes the solubility data and the resist characteristics of the nanocomposite resists. The solubility of C60 in o-DCB tends to increase by introducing functional groups. However, single adducts of metanofullerenes (C60C^2 and C60CMO^2) are not soluble at all. Double adducts are, on the whole, more soluble than single ones. Two derivatives, C]0(NEO3)2 and C]0(CMO^2)2. are soluble in a photoresist solvent, propylene glycol 1-monomethyl ether 2-acetate (PGMEA). Of these two, C60(CMO^2)2 is extremely soluble (>100 g/L) in PGMEA.
We prepared six [email protected] in the same manner as [email protected] They are denoted [email protected], [email protected], C60N^O^@ZEP, C60(NEO3)[email protected], C60(C^2)[email protected], and C60(CMO^2)[email protected] for simplicity. The two single-adduct metanofullerene derivatives mentioned above could not be used for resist preparation because of their insolubility in o ]DCB. Resist characterization was done in the same way as for [email protected] or C60/[email protected] The sensitivity and resolution of [email protected], [email protected], and C60N^@ZEP were evaluated with the JBX-5FE, while those of C60(NEO3)[email protected], C60(C^2)[email protected], and C60(CMO^2)[email protected] were done with a 100-kV electron-beam machine (JBX-9300FS)  . Resolution was evaluated by measuring line-and-space patterns with 100-nm pitch and 150-nm height.
Figure 9.34 shows the normalized etch rate of the six C][email protected] against fullerene-derivative content. On the whole, etch rates of all the C60-derivative @ ZEPs tend to decrease with content. However, the decrease is moderate, about
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