Steven W. Fornaca

Xenon target performance characteristics for laser-produced plasma EUV sources

Laser-produced plasmas (LPPs) are being developed as light sources for EUV lithography. To meet the requirements for high-volume manufacturing, LPP EUV sources must generate intense EUV output in the 13.5 nm band, and minimize source-induced degradation of EUV optics allowing hundreds of hours of clean operation. Xenon has been identified as a promising target material for LPP EUV light sources, with the potential for both high-efficiency EUV generation, and low optics contamination. Several dense xenon target configurations have been tested including aerosol sprays, continuous liquid streams, condensed xenon droplets, and frozen solid xenon. Important LPP performance characteristics, such as conversion efficiency, EUV radiation distribution, EUV optics degradation by material erosion and/or deposition, and the physical interface to the EUV optical system, are strongly influenced by the xenon target design. The performance of xenon targets with measured conversion efficiencies in the 0.4 percent to 1.4 percent range is reported. Prospects for xenon targets to reach the EUV power generation and contamination goals for production lithography tools are addressed.

Laser-produced plasma (LPP) scale-up and commercialization

An EUV light source, created when a high-average power (750 W) Nd:YAG laser forms a plasma in a xenon liquid-spray jet, has been characterized. This source has shown improved conversion from laser to EUV, and a more uniform angular distribution, as the laser pulse energy and average power are increased. System performance has been analyzed and compared with the requirements for future EUV microlithography tools for semiconductor manufacturing. EUV power scaling requirements and factors influencing Cost-of-Ownership are discussed.

Passive millimeter-wave video camera

A passive millimeter-wave (PMMW) camera capable of generating a real time display of the imaged scene, similar to video cameras, has been developed at TRW and is undergoing field testing. The camera operates at 89 GHz, acquiring images at a frame rate of 17 Hz. This work reports on the video imaging generated by the camera. This research is carried out under the Passive Millimeter-Wave Camera Consortium, a cost-shared program between the Defense Advanced Research Programs Agency and an industrial consortium that includes Honeywell, McDonnell Douglas and TRW. It is managed for the Department of Defense by NASA-LaRC.

Passive millimeter-wave camera flight tests

TRW has developed a passive millimeter wave demonstration camera using its unique millimeter wave monolithic integrated circuit (MMIC) technology. It operates in a 10 GHz band around 89 GHz, has a field of view of 10 degree(s) by 15 degree(s), and can process and display data in real-time at video rates. Its focal plane consists of 1040 MMIC direct detection receivers.

Laser-produced plasma light source for extreme ultraviolet lithography

Pulsed Nd:YAG lasers have been developed to achieve high peak power and high pulse repetition rate. These systems are being used as drivers for laser-produced plasmas which efficiently convert the 1064-nm laser output to extreme ultraviolet (EUV) light at 13.5 nm for future microlithography systems. The requirements for laser-produced plasma EUV light sources and their integration in lithography tools for high-volume manufacturing are reviewed to establish the key design issues for high-power lasers and plasma targets. Xenon has been identified as a leading target material to realize the goals of intense EUV emission and clean operation. Recent progress in high-power diode-pumped Nd:YAG lasers and xenon targets for EUV generation is reviewed, showing that laser-produced plasma sources meet the needs for current EUV lithography development tools. Future directions to meet EUV source requirements for high-volume manufacturing tools are discussed.

Large-aperture passive millimeter-wave pushbroom camera

TRW has developed a new passive millimeter wave camera for the Navy using its unique Millimeter Wave Monolithic Integrated Circuit (MMIC) technology. It operates as a pushbroom or scanning imager and can be utilized for missions that do not require as rapid a frame rate as in video-rate imagery. It is designed as a large-aperture, wide-field-of-view camera. Its focal plane consists of two rows of MMIC-based direct detection receivers and provides full sampling of the imaged scene.

Large scale W-band focal plane array developments for passive millimeter wave imaging

A state-of-the-art W-Band passive millimeter wave focal plane array (FPA) consisting of 1040 highly integrated direct detection pixel has been designed, developed, assembled and tested. The FPA has been integrated into a passive millimeter wave video camera and has generated real time images. Each pixel is a highly integrated MMIC chip receiver. The MMIC chip is a wide band, high gain, low noise, 0.1 micrometer InGaAs HEMT amplifier with an integrated switch and Schottky barrier diode detector. The FPA uses a brick architecture. Each brick or module consists of 4 MMIC chips or pixels and lay side-by- side on the card. Many cards are stacked to create the array of pixels. In the next generation FPA, the 1 X 4 modules and cards have been dramatically simplified with 50% less assembly time. In addition, the module and card still require no tuning and minimal test time. Thus a significant cost reduction in the FPA is expected over the first generation FPA without sacrificing performance. To further reduce cost and improve performance, new MMIC chips are being designed.

Detection of metal and plastic mines using passive millimeter waves

In a continuing effort to develop new sensor technologies for the detection of land mines and other UXO, a variety of plastic and metal mines were acquired for detection tests utilizing a passive millimeter wave sensor at 44 GHz and at 12 GHz. These inert mines were surface- laid, covered with dry leaves, or buried in sand or soil, and the resulting target scene was scanned from an overhead position using the single channel sensor, generating a 2D image of the minefield.

Passive millimeter wave camera for enhanced vision systems

Passive millimeter wave (PMMW) sensors have been proposed as forward vision sensors for enhanced vision systems used in low visibility aircraft landing. This work reports on progress achieved to date in the development and manufacturing of a demonstration PMMW camera. The unit is designed to be ground and flight tested starting 1996. The camera displays on a head-up or head-down display unit a real time true image of the forward scene. With appropriate head-up symbology and accurate navigation guidance provided by global positioning satellite receivers on-board the aircraft, pilots can autonomously (without ground assist) execute category 3 low visibility take-offs and landings on non-equipped runways. We shall discuss utility of fielding these systems to airlines and other users.

140-GHz passive millimeter-wave video camera

TRW has recently developed InP low noise amplifiers operating at 140 GHz. Similar to the evolution of 94 GHz GaAs technology, this lays the foundation for the development of a 140 GHz MMIC receiver for use in a next generation passive millimeter-wave video camera capable of generating a real time display of the imaged scene. The advantages of going to 140 GHz, and the use of InP technology, will be discussed.