Optical lithography in integrated circuit fabrication presently consists of about 20 successive mask steps. Up to now no calibrated two dimensional photomask position standard (2DPPS) traceable to the SI unit of length exists; metrological institutes can supply only one dimensional line scale calibrated with sufficient accuracy.
A two dimensional standard mask is a necessary tool to examine the dimensional tolerances of successive production steps, in order to ensure the quality of instruments (eg pattern generators, wafer measuring machines, wafer steppers, mask measuring machines) and to avoid commercial disputes.
The aim of the project is to produce for industrial calibration purposes a 7" calibrated 2DPPS accurate and certified to 50 nm, thus meeting the requirements of lithography for the 0.3 um geometries (64 Mbit DRAM, 80 nm overlay accuracy). This standard will later be made available as a calibration reference to the semiconductor and equipment industry. The project will also investigate the instrumentation and the substrate requirements necessary to achieve a future 10" calibrated 2DPPS.
The work is in progress.
Funding SchemeCSC - Cost-sharing contracts
TW11 0LW Teddington