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Fast Reticle Equipment for Europe

Objective

The proliferation in the number of designs for ASICs, the increase in the number of functions per chip, and the decrease in the minimum feature size, necessitate faster turn-around times not only for IC prototypes, but also for mask fabrication tools. This, together with current demands and projections toward 0.3 micron minimum feature size, larger chips and higher placement accuracy, 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 fast reticle equipment for Europe (FREE) project aimed at the development of a new electron beam writing system for reticle fabrication that will answer the needs of the European integrated circuit (IC) industry for at least the next decade. The target specifications of the system were a throughput of 2 reticles per hour, with a minimum feature size of 1.5 micron (5x reticle), and capable for writing small test structures down to 0.2 micron. It was to attain a placement accuracy of 70 nm (0.07 micron) for 6inch reticles and critical dimension (CD) tolerance of 50 nm (0.05 micron), both at 3 sigma. 2 beam-writing strategies were followed: beam shaping techniques (ELISA), in order to speed up the writing of large features, and a gaussian electron beam system (Leica Cambridge) with increased writing speed. Both basic systems already existed from the start, but required improvements in several areas. During the project the 2 machines were upgraded to achieve the writing objectives.
A thermal field emitter source giving a higher brightness thant lanthanum boride and a 16 tungsten hairpin filament assembly with a long lifetime were designed and characterized. The design of a new column associated with high frequency detection (up to 25 MHz) was constructed and characterized. To achieve high throughput, the data rate handled by the pattern generator must be significantly improved. This was achieved by data compression techniques and higher electronic speeds for data transfer. Suitable designs were prepared in order to change the current batch loading strategy to a serial, single blank high speed handler that would be compatible with other reticle fabrication tools. Very high current densities are needed to achieve very high writing speeds. A very high sensitivity, short processing time and dry etch compatible resist has been synthesized and characterized.
At the end of the project, evaluation of both the variable shaped and gaussian beam machine against the ultimatel y desired specifications were performed. Both machines showed significant improvement over the initial configurations, offering good prospects for the consolidation of a European system capable of competing in world markets. A comparison between them revealed their strong and weak points, and plans for further improvements were presented.
The target specifications of the system were a throughput of two reticles per hour, with a minimum feature size of 1.5 micron (5x reticle), and be capable of writing small test structures down to 0.2 micron. It was to attain a placement accuracy of 70 nm (0.07 micron) for 6" reticles and critical dimension (CD) tolerance of 50 nm (0.05 micron), both at 3 sigma. Two beam-writing strategies were followed: beam-shaping techniques (ELISA), in order to speed up the writing of large features, and a gaussian electron beam system (Leica Cambridge) with increased writing speed. Both basic systems already existed from the start, but required improvements in several areas.

Coordinator

EUROPEAN LITHOGRAPHY INNOVATION (ELISA)
Address
1 Placette De La Marjolaine
91440 Bures Sur Yvette
France

Participants (6)

Cambridge Instruments Ltd
United Kingdom
Address
Rustat Road
CB1 3QH Cambridge
NATIONAL RESEARCH CENTRE FOR SCIENTIFIC RESEARCH DEMOKRITOS
Greece
Address
Aghia Paraskevi, 60228
15310 Athenes
TECHNISCHE UNIVERSITEIT DELFT
Netherlands
Address
Feldmannweg 17, 5053
2600 GB Delft
Thomson Microelectronics Srl (SGS)
Italy
Address
Via Carlo Olivetti
20041 Agrate Brianza Milano
UNIVERSITY OF CAMBRIDGE
United Kingdom
Address
Madingley Road
CB3 0ES Cambridge
Valvo Unternehmensbereich
Germany
Address
Burchardstraße 19
20095 Hamburg