Nano-scale fluctuations in electron beam resist pattern evaluated by atomic force microscopy

The resist pattern fluctuations on the nano-scale are successfully observed using a dynamic force mode AFM. A scaling analysis based on the fractals applies to the AFM images for quantitative evaluation of the fluctuations. The standard deviation of width fluctuations in a ZEP resist pattern is 2.8 nm. The scaling analysis confirms that the surface morphology of the pattern sidewall is almost the same as that of the resist film lightly exposed by an electron beam. The main cause of the fluctuation is structures with a diameter of 20–30 nm which are composed of large groups of molecules.