Lucent steps and scans with electron-beam lithography
In November, researchers from Lucent Technologies (Murray Hill, NJ) reported that their electron beam (e-beam) lithography project has advanced to the "ste¥and scan" stage. The Lucent team scanned a pattern mask to print a stripe of features on a wafer, then shifted the mask and wafer to print another stripe immediately next to and in precise alignment with the previous one. By printing four adjacent stacks of 100 stripes each, the researchers produced a 1-cm2 field of semiconductor features. Stripes produced in the demonstration were aligned with an accuracy of at least 0.05 µm. Lucent has registered the mnemonic SCALPEL (SCattering with Angular Limitation Projection Electron-beam Lithography) as the name for the DARPA- and Sematech-funded project, which, along with x-ray and extreme-ultraviolet techniques being pursued by others, targets the projected limitations of current optical lithography methods in semiconductor manufacturing. The SCALPEL system printed its first 0.08-µm features in 1996. Continuing development of SCALPEL toward commercial viability will include writing fields larger than the current 1 ¥ 1-cm demonstration, building system speed to achieve commercial levels of throughput, and developing a multiple-stage process for writing features on to¥of areas where features have already been written.