Carl Zeiss Semiconductor Metrology Systems (SMS) division’s registration and overlay metrology system has successfully passed a key development milestone. The system, called PROVE, was developed by both SEMATECH and Carl Zeiss. The two companies demonstrated the measurement capability for advanced photomasks for the 32 nm node and below. In a series of test runs, 0.5 nm repeatability and 1.0 nm accuracy in image placement, registration and overlay measurement were verified.
The industry now has the capability to determine smaller image placement errors than could be measured before. The mask pattern placement metrology tool project enables the International Technology Roadmap for Semiconductors (ITRS) mask requirements for the 32 nm node and below. The PROVE system will help to advance the development of photomasks with tighter overlay requirements, demanded by memory devices and double patterning methods.
The performance targets of the tool were driven by the requirements for advanced memory and double exposure/double patterning mask pattern placement and overlay that will help extend 193nm lithography according to the ITRS.
The PROVE 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.
The technology represents a significant improvement over previous capability due primarily to the incorporation of high-resolution 193nm wavelength imaging optics, a flexible illuminator that maximizes image contrast, a highly versatile in-die registration analysis algorithm, and a state-of-the-art metrology platform. The PROVE system can be fully extended to measure EUV photomasks. The tool will play a vital role in enabling next generation mask-making technology.