The steady increase in the number of functions per chip and the decrease in the minimum feature size necessitate faster turnaround times for mask fabrication tools and also for IC prototypes. The projection towards 0.35 micron feature size and beyond requires larger chips with higher placement accuracy and dictates the need for a new generation of tools for mask and reticle fabrication. The FREE project aimed at the development of a new electron-beam writing system for reticle fabrication that will answer the needs of the European IC industry for at least the next decade.
The target specification of the system was set at two reticles per hour with a minimum feature size of 1.5 microns (5x reticle) while at the same time writing test structures down to 0.2 micron. The original target of placement accuracies better than 0.07 micron, with CD tolerances of 50 nm and CD linearity iof the same order, has stood the test of time. In the first programme, two E-beam writing strategies were followed; the beam shaping techniques (ELISA) and the gaussian electron-beam system (Leica Cambridge). Both companies had basic systems but required significant improvements in several areas in order to meet the demanding targets of this programme. This part of the programme was completed in February 1992 and the decision taken to proceed to the second part with the gaussian electron beam system from Leica Cambridge.
This second part of the programme is aimed at producing a beta site machine so that requirements can be evaluated in a merchant mask shop in a live commercial environment. In this part, Leica Cambridge are to produce a Vectorscan gaussian beam system designed to meet the objectives and ELISA are to produce a robotics handling system in order to meet the requirements for defect free mask production.
91440 Bures Sur Yvette
2600 GB Delft
20041 Agrate Brianza Milano
CB3 0ES Cambridge