High aspect-ratio (more than 10) microfabrication of crosslinked polytetrafluoroethylene (PTFE) has been carried out using synchrotron radiation (SR) direct photo-etching, The etching rates of crosslinked PTFE samples with various crosslinked densities were studied by changing photon fluence of SR at different sample temperatures, The etching rate of the sample with W-her crosslinking density resulted in a higher etching rate. This rate was about two times higher than that of normal PTFE. The temperature dependence of the etching rates indicated that molecular motion of alpha-relaxation of samples and structures of smaller fragments (i.e., etched products) produced by irradiation of SR with high dose rate play an important role for SR direct photo-etching. Moreover, we have found that surface modification of PTFE had been proceeding during irradiation of SR to the PTFE at 140 degreesC. The results of differential scanning calorimeter measurements for the modified layers showed that the layers might have crosslinking character. (C) 2002 Elsevier Science B.V. All rights reserved.