Fast Reticle Equipment for Europe

FREE-2 - 7804

Keywords reticles, E-beam generators, resists

Start Date: 15-DEC-92 / Duration: 18 MONTHS

[ contact / participants ]

Objectives and Approach

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.

The second part of the programme, project 7804, 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.

Progress and Results

The vector gaussian beam machine has now been operational for some nine months where the major innovation have been evaluated on a standard 5" stage. It will shortly be converted to a new 6" stage system which is capable of accepting reticles and wafers up to 8" for both mask manufacture and direct writer applications.

Source: A thermal field emitter source giving high brightness has been specifically designed for lithography applications an is on test at DIMES

Column: The design of a new column associated with high frequency deflection (up to 25 MHz clock rate, with slewing rates greater than 200 MHz) has been constructed and characterised.

Pattern manipulation system: To achieve the high throughput, a data handling pattern manipulation system has been developed with significant advances in terms of throughput conversion times and pattern file data reduction.

Automatic loading: A robotics system has been developed and is currently being manufactured to provide serial loading of blank mask with a high speed, contamination free handler which will be compatible with other reticle fabrication tools.

Resist processing: High sensitivity (<1 micron/cm{2}) positive and negative resist are being developed with short processing time and dry-etch capability. These are currently on evaluation.

Beta site: A beta site is being prepared in the Du Pont commercial mask shop ready for the field evaluation of the prototype E-beam lithography tool and at the same time, the automatic loading system will be beta site evaluated on an associated site.

A the end of the second phase of the project, evaluation of both the E-beam lithography tool and the automatic loading system will be reported and compared with the currently recognised standard machines for this application.


Peter Mitchell
Senior Engineering Manager
Leica Cambridge Ltd
Clifton Road
UK - Cambridge CB1 3QH
tel: + 44/ 223 411411
fax: + 44/ 223 211310



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FREE-2 - 7804, December 1993

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html version of synopsis by Nick Cook