Pattern transfer by direct photo etching of poly(vinylidene fluoride) using X rays

A direct pattern transfer method has been developed by photo etching poly(v inylidene fluoride) (PVDF) using X rags (1-16 keV) from a synchrotron stora ge ring. The ability to pattern thin film of PVDF; a piezoelectric, pyroele ctric and ferroelectric polymer, has potential applications in the areas of MEMS, nonlinear optics, and nonvolatile ferroelectric random access memory technology. Without the use of any reactive chemical gas, a maximum etched depth in excess of 9 mu m is achieved, The etched depth for a given photon energy approaches saturation with respect to exposure time. An in situ mas s spectrometry revealed the evolution of hydrogen, fluorine, and hydrogen f luoride species. The etched regions turned dark in color indicating a possi ble increase in the fraction of carbon atoms. The X-ray transmittance of ph oto etched PVDF approached that of a pure carbon as the exposure time is in creased. Upon etching the root mean-square surface roughness of the etched portion increased by more than a factor of two, The rate of etching increas ed at elevated sample temperatures. [446].