Deep X-ray Lithography for MEMS — Photoelectron Exposure of the Upper and Bottom Resist Layers

X-ray lithography technology, suggested by Henry Smith in 1972, has been successfully under development for nearly 30 years, but it has not been applied in commercial IC production despite having a demonstrated resolution of 30 nm. This is connected with an unpredicted breakthrough in technology of photolithography to a fantastic resolution of 0.1 gm. Nevertheless, x-ray lithography could be the best choice for some new applications such as an extremely high resolution deep lithography for MEMS. In comparison with conventional photolithography, this new technique has no problems connected with the radiation scattering in a resist or reflection from a substrate and a mask, as well as standing waves and related swing curve effects, because of the x-rays nature. However x-ray lithography has some specific technological problems related with the exposure of the top and bottom resist layers with photoelectrons produced in a mask and a substrate during x-rays exposure.