Characterization of High Resolution Resists and Metal Shims by Scanning Probe Microscopy

Technologies such as compact disc (CD) manufacturing, hologram embossing, and security printing rely on the reproduction of micro-patterns generated on surfaces by optical or electron-beam lithographic writing onto electron-beam or photoresists. The periodicity of such patterns varies from sub-micron to several microns, with depths up to 0.5 µm. The scanning probe microscope (SPM) is becoming a routine tool for analysis of these micro-patterns, to check on depths and lateral dimensions of features. Direct scanning of resist-covered plates is now possible, without damage, using resonant low-contact force SPM with etched silicon cantilevers. Metal shims produced from the master resist plates can also be scanned and checked for defects prior to production of embossed foils. The present article discusses examples of the use of a Digital Instruments 3100 microscope in analysis of production electron-beam lithography plates with a 0.5 µm resist thickness. We also examine features of nickel replicas ("father" and "mother" shims) produced by electroforming from the original plate. With SPM measurements of the development profile of a particular plate, corrections can be made to exposures and development times during production to correct errors. An example is given of such a feedback process.