Electron beam and scanning probe lithography: A comparison

sElectron beam lithography (EBL) and scanning probe lithography (SPL) are e lectron exposure techniques capable of high resolution patterning of organi c resists. This article compares the exposure properties of these two syste ms. We consider the resist sensitivity to EEL and SPL electrons, exposure t olerances, patterning linearity, and proximity effects. It is possible to p rint sub-50 nm features using both systems, but SPL has a wider exposure la titude at these small feature sizes. SPL requires a significantly higher in cident electron dose for exposure than does EEL. In EEL, lithography contro l is most limited by proximity effects which arise from backscattered elect rons whose range is considerably larger than the forward scattering range i n the resist film. As a result, the exposed feature dimension depends stron gly on the local feature density and size, leading to unacceptable linewidt h variations across a wafer. These limitations are alleviated in the case o f SPL exposures. We demonstrate improved linearity and reduced proximity ef fects with SPL. We have patterned 200 nm pitch grids with SPL where all ind ividual features are resolved. The Linewidth of features in these grids is the same as the width of an isolated line at the same dose. Finally, we sug gest that the SPL exposure mechanism may be different than that for EEL. (C ) 1998 American Vacuum Society. [S0734-211X(98)15306-4].