Charge-reducing Effect of Chemically Amplified Resist in Electron-Beam Lithography

The charging effect of chemically amplified resists in electron-beam (EB) lithography is described. The results of pattern placement error caused by the charging effect using SiO 2 substrates with various thicknesses revealed that the resist with polyhydroxystyrene (PHS) has the ability to reduce the pattern placement error due to the charging effect as compared to the resist, SAL601. From the measurement of the surface resistance of the resist, it was found that the surface resistance of the resist with PHS decreases from 10 17 Ω to 10 12 Ω after UV exposure, even though no change in surface resistance was observed for SAL601. These results imply the following: (1) the charge-reducing effect of the resist with PHS is related to EB bombardment-induced conductivity of resist and (2) the deposited charge in the resist with PHS dissipates at a rate sufficient to avoid charging problems as a result of a leakage current through the surface of SiO 2 film or electron-beam-induced current (EBIC). In this paper, we report the experimental results and the possible mechanism to explain the charge-reducing effect of the resist with PHS.