No abstract

No abstract

CD uniformity is one of the most critical parameters for mask making today. The mask error factor (MEF) in lithography for features that are smaller than the stepper wavelength means that any CD error is transferred to the wafer to a greater extent than the stepper reduction factor would indicate. CD results form a new laser pattern generator, the Omega6000 product line, will be presented. The system features an acousto-optic deflection architecture specifically designed to meet the CD requirements of 180 nm photomasks. A 0.86 NA final lens provides the high resolution ofthe system. The CD control and the high resolution makes the system well suited for today's advanced photomasks.

With each new technology generation, photomask manufacturing faces increasing complexity due to shrinking designs and accelerating use of reticle enhancement techniques. Denser and more complex patterns on the mask result in lower yields and long write and turn-around times, important factors for the rapidly increasing mask related costs in IC manufacturing.Laser pattern generators operating at DUV wavelengths were recently introduced to provide cost effective alternatives to electron-beam systems for printing of high-end photomasks. DUV wavelengths provide the required resolution and pattern fidelity. Optical tools that use raster writing principles and massively parallel printing ensure short and predictable write times for photomasks almost independent of pattern complexity.One such high-volume production system, the Sigma7300, uses spatial light modulator (SLM) technology and a 248 nm excimer laser for printing. Partially coherent imaging and multi-pass printing as in a lithography scanner further increases resolution and pattern accuracy. With four-pass printing the system provides resolution and pattern accuracy meeting mask requirements for critical layers at the 90-nm node and sub-critical layers at the 65-nm node and beyond.The paper discusses how mask layout can be optimized to take full advantage of the speed potential provided by the SLM-based writer. It shows how flexible use of the writing principle can provide cost effective writing solutions for many layers in high-end mask sets. Resolution and pattern accuracy results from the Sigma7300 will be presented together with write times for different types of designs.

No abstract