Tom A. Watson

Production-ready 2-kHz KrF excimer laser for DUV lithography

Now that 1000 Hz KrF excimer laser based DUV lithography tools are firmly established in production, emphasis is shifting from development towards improving the productivity and profitability of the manufacturing process, thereby reducing the cost per wafer. In this arena, laser manufacturers are competing now not only on performance but also on cost and productivity enhancements that the laser can offer to the lithography process.

Next-generation 193-nm laser for sub-100-nm lithography

The next generation 193 nm (ArF) laser has been designed and developed for high-volume production lithography. The NanoLithTM 7000, offering 20 Watts average output power at 4 kHz repetition rates is designed to support the highest exposure tool scan speeds for maximum productivity and wafer throughput. Fundamental design changes made to the laser core technologies are described. These advancements in core technology support the delivery of highly line-narrowed light with <EQ 0.35 pm FWHM and <EQ 0.95 pm at 95% included energy integral, enabling high contrast imaging from exposure tools with lens NA exceeding 0.75. The system has been designed to support production lithography, meeting specifications for bandwidth, dose stability (+/- 0.3% in 20 ms window) and wavelength stability (+/- 0.05 pm average line center error in 20 ms window) across 2 - 4 kHz repetition rates. Improvements in optical materials and coatings have led to increased lifetime of optics modules. Optimization of the discharge electrode design has increased chamber lifetime. Early life-testing indicates that the NanoLithTM core technologies have the potential for 400% reduction of cost of consumables as compared to its predecessor, the ELX-5000A and has been discussed elsewhere.

ArF lasers for production of semiconductor devices with CD < 0.15 μm

The present day notion of the extensibility of KrF laser technology to ArF is revisited. We show that a robust solution to ArF requirements can be met by significantly altering the lasers core technology-discharge chamber, pulsed power and optics. With these changes, a practical ArF tool can be developed. Some of the laser specifications are: Bandwidth: 0.6 pm (FWHM) 1.75 pm (95% Included Energy); Average Power: 5 W; Repetition Rate: 1000 Hz; Energy Stability (3(sigma) ): 20% (burst mode) 8% (continuous); Pulse Width: 25 ns.

Excimer lasers for DUV lithography

Summary form only given. The use of KrF and ArF excimer lasers as exposure sources for deep ultraviolet (DUV) lithography is discussed. Driven by extreme demands on performance, these lasers continually push the state-of-the-art in excimer laser design. Past, present, and future performance characteristics for these lasers are presented.

Performance characteristics of a high-energy, high-pulse repetition frequency krypton fluoride laser

As applications have evolved out of the research areas, laser beam properties and component lifetimes have become critical to achieving low operating cost in a manufacturing environment. We will discuss the development of a 110 watt KrF laser using an all solid-state pulsed power system. Solid state pulsed power enables a significant reduction in system operating costs by greatly extending the exchange interval of the pulsed power and discharge chamber modules. Beam properties of the laser using both stable and unstable resonator configurations will be discussed.