Microradiography with laser-produced plasma sources - surface roughness on pmma resist

The use of a laser produced plasma as an x-ray source for high resolution microradiqgraphy has several advantages over conventional x-ray sources: a very small source size (<100 pm in diameter) and a pulsed exposure with a less than 1 ns duration. The former provides the possibility of high spatial resolution, and the latter produces high temporal resolution. It has been proposed that the pulsed exposure is ideal for imaging living biological specimens. In order to obtain high resolution images, modern microradiography uses high molecular wight polymers (photo-resists) as the photochemical detector on which a surface relief image is formed. Therefore, one of the factors affecting image resolution is the surface roughness of the resist. This paper reports the surface roughness on the resist polymethyl methacrylate (PMMA) which has been exposed to the radiation from a laser-produced plasma x-ray source. The surface roughness was investigated by transmission electron microscopy using a metal replica technique.