The jointly developed ‘PROVE’ overlay metrology system between Carl Zeiss and SEMATECH has successfully passed a key development milestone, according to the partners. The system has achieved .5nm repeatability and 1.0nm accuracy in image placement, registration and overlay measurement for double patterning photomasks, a key requirement for extending 193nm ArF lithography to the 32nm node and below.
“The mask pattern placement metrology tool project builds upon an already successful partnership between Carl Zeiss SMS and SEMATECH for past work on mask Aerial Image Metrology Systems (‘AIMS’) tool platforms. The partnership has resulted in a working metrology tool that is meeting specifications for repeatability, reproducibility, and accuracy at the 32 nm half-pitch node,” commented Bryan Rice, director of lithography at SEMATECH.
The technology was said to be significant improvement over previous systems due primarily to the incorporation of high-resolution 193nm wavelength imaging optics as well a flexible illuminator that maximizes image contrast. A highly versatile in-die registration analysis algorithm was also developed. The system was said to be able to measure EUV photomasks as well.
“The system is based on a completely new developed platform enabling in-die and sub-nanometer pattern placement metrology in a most versatile way. The measurements can be done on arbitrary production features in the active area of the photomask for accurate and cost efficient metrology and is extendable to EUV technology,” said Dr. Oliver Kienzle, Managing Director of Carl Zeiss SMS. “We will now roll-out the PROVE product with deliveries to our customers.”