| he work reported here describes the synthesis, characterization and radiation sensitivity of polyimides which contain cyclobutane dianhydride units in the backbone of the polymer chain. The parent dianhydride of this series, as well as various substituted compounds, was prepared and polymerized with appropriate diamines. It was demonstrated that not only are these products colorless, film-forming and thermally stable, but that they are also sensitive to ultraviolet and electron beam irradiation. The sensitivity manifests itself in enhanced solubility caused by chain cleavage reactions of the high molecular weight polyimide backbone. Evidence is presented which indicates that the mechanistic process which produces cleaved chains terminated with maleimide units is a radiation-induced retrocyclization reaction analogous to the cyclodimerization used to prepare the anhydrides. Experiments were conducted to demonstrate that micron-scale images could be generated in these materials directly with masked ultraviolet light or focussed electron beams without the use of other resist technologies.;The publications collected here are: (1) "An Intrinsically Photosensitive Polyimide ", J. A. Moore and A. N. Dasheff, Chemistry of Materials, 1, 163 (1989). (2) "A Soluble Photosensitive Polyimide", J. A. Moore and A. N. Dasheff, in Polyimides: Materials, Chemistry and Characterization, edited by C. Feger, M. M. Khojasteh and J. E. McGrath, Elsevier Science Publishers B. V., Amsterdam, 1989, p. 115-122. (3) "Electron-Beam Positive Polyimides", J. A. Moore and Andrew N. Dasheff, Proceedings of the Third International Conference of the Society for Advanced Materials Processing and Engineering, "Electronic Materials for the 90's and Beyond", Los Angeles, CA, June 1989. (4) "Positive-Working Photosensitive Polyimide Operated by Photo-induced Molecular Weight Changes, James A. Moore, Andrew N. Dasheff and Frank B. Kaufman, United States Patent... |
