As extreme-ultraviolet (EUV) lithography moves into pre-production, the requirement for commercially available mask metrology tools becomes more urgent. A key to developing a successful tool is a reliable, high-brightness EUV light source. The Energetiq EQ-10 is a commercially available EUV light source, with an installed base of over 15 sources in the field. The source relies on an electrodeless Z-pinch™ to produce greater than 10 Watts/2π of 13.5 nm 2% bandwidth light. In order to meet brightness and stability requirements of mask metrology tools, we have investigated modifications to the original design of the EQ-10. The result of these modifications has roughly doubled the source output power, and has achieved brightness greater than 8 Watts/mm2/sr, without sacrificing the spatial and pulse-to-pulse stability of the original design. This level of performance is sufficient for initial mask blank and imaging inspection tools.
Energetiq Technology has been shipping the EQ-10 Electrodeless Z-pinchTM light source since 1995. The source is
currently being used for metrology, mask inspection, and resist development. Energetiq's higher brightness
source has been selected as the source for pre-production actinic mask inspection tools. This improved source enables
the mask inspection tool suppliers to build prototype tools with capabilities of defect detection and review down to 16nm
In this presentation we will present new source technology being developed at Energetiq to address the critical source
brightness issue. The new technology will be shown to be capable of delivering brightness levels sufficient to meet the
HVM requirements of AIMS and ABI and potentially API tools. The basis of the source technology is to use the stable
pinch of the electrodeless light source and have a brightness of up to 100W/mm(carat)2-sr. We will explain the source design
concepts, discuss the expected performance and present the modeling results for the new design.
With EUV Lithography systems shipping, the requirements for highly reliable EUV sources for mask inspection and
resist outgassing are becoming better defined, and more urgent. The sources needed for metrology applications are very
different than that needed for lithography; brightness (not power) is the key requirement. Suppliers for HVM EUV
sources have all resources working on high power and have not entered the smaller market for metrology.
Energetiq Technology has been shipping the EQ-10 Electrodeless Z-pinch<sup>TM</sup> light source since 19951. The source is
currently being used for metrology, mask inspection, and resist development2-4. These applications require especially
stable performance in both output power and plasma size and position.
Over the last 6 years Energetiq has made many source modifications which have included better thermal management to
increase the brightness and power of the source. We now have introduced a new source that will meet requirements of
some of the mask metrology first generation tools; this source will be reviewed.
Now that EUV lithography systems are beginning to ship into the fabs for next generation chips it is more critical that
the EUV infrastructure developments are keeping pace. Energetiq Technology has been shipping the EQ-10
Electrodeless Z-pinch™ light source since 2005. The source is currently being used for metrology, mask inspection,
and resist development. These applications require especially stable performance in both power and source size.
Over the last 5 years Energetiq has made many source modifications which have included better thermal management as
well as high pulse rate operation6. Recently we have further increased the system power handling and electrical pulse
reproducibility. The impact of these modifications on source performance will be reported.
A novel technology has been developed which enables high-brightness, broadband light output from the VUV to the IR
spectral regions. A focused laser is used to sustain a high-pressure xenon discharge inside a bulb, creating a smaller,
hotter discharge than can be obtained by using an electrically-driven discharge. This allows for continuous output down
to 120 nm wavelength and into the infrared. Application areas include hyperspectral imaging, standoff detection,
surveillance, bioanalytical instrumentation, microscopy, and materials studies. Laser-driven optical discharges were first
investigated over 30 years ago, providing the initial technical understanding of such discharges. However it took the
convergence of two separate elements - the availability of low-cost, high-efficiency CW diode lasers; and a market need
for high-brightness, broadband light source - to provide the impetus for further development in this area. Using near-IR
CW diode lasers at power levels from 15 W to over 2000 W, we have generated high-pressure xenon discharges having
temperatures as high as 10,000 C. The optical brightness of these discharges can be over an order of magnitude higher
than those obtainable from the brightest xenon arc lamps, and can be several orders of magnitude brighter than
deuterium lamps. Results from modeling of these discharges as well as experimental measurements will be presented.
With EUV Lithography readying for production, the need for commercially available actinic mask inspection tools is
critical. A key to developing a successful tool is a reliable high brightness EUV light source. The Energetiq EQ-10 is a
commercially available EUV light source, with demonstrated reliability of over 15 sources in the field. It is being used
today for laboratory based actinic mask blank inspection at Selete<sup>4</sup>.
Results will be presented from a program to optimize the EQ-10 for higher brightness. The platform used for this work is
a new version of the EQ-10. The redesigned source demonstrates increased EUV power and brightness compared to the
standard EQ-10. The program aims to optimize source operating conditions and pinch geometries of the new source to
The Energetiq EQ-10 is a medium-power (10 W/2π, 13.5nm +/- 1%, Xenon) EUV source suitable for a variety of mirror testing, resist exposure, and defect inspection applications. The EQ-10 was designed to operate at a pulse frequency of 1 to 2 kHz<sup>1</sup>. However, exposure equipment appropriate for High Volume Manufacturing (HVM) requires sources which are projected to operate at 10 kHz or greater<sup>2</sup>. To minimize technical risk in infrastructure development programs now under way in support of future HVM production, scaling of various physical processes with pulse rate require investigation. A program to redesign the EQ-10 to operate at 10 kHz pulse rate has been completed. We report here on the design process and the operating characteristics of the high-frequency source.
As industry advances towards the insertion of EUVL technology, researchers and manufacturers armed with alpha EUV
light sources invent an expanding array of potential applications utilizing these sources. This in turn drives development
of the light sources to fulfill the large field of specific needs in resist exposure, mirror testing, wafer inspection, etc., which
call for a greater variety of source parameters, including output power, source size, and stability.
The EQ-10 is a commercially available, medium-power (10 W/2π, 13.5nm ±1%, Xenon) electrodeless Z-pinch light
source. Significant field experience and customer feedback has been accumulated from sources already in operation in
multiple locations. In response, a development program is under way to re-engineer and optimize the EQ-10 for a variety
of applications. Data will be presented on the effect of varying source geometry, frequency, and input power on pinch
performance. We have observed a sustained integrated output power of over 15 Watts. The plasma size can be varied to
suit customer applications.
A related program on beamline design and optimization is also underway, focused on debris mitigation while also
maintaining the efficiency of EUV power delivery. Initial results from this program will be summarized.
Formulating high sensitivity and high resolution EUV Resists is a
critical issue gating the adoption of EUV lithography. The ability of
resist manufacturers to quickly screen outgassing rates and
sensitivity of EUV resists will facilitate faster formulation of a
production-ready EUV photoresist. The high power and low cost per
watt of the Energetiq EQ-10 light source enables relatively simple
designs without complex optics to deliver relevant data efficiently.
Because the source operates without electrodes, a significant source
of contamination is removed, further simplifying the design of
Data will be presented from two prototype exposure systems. The
first, in operation at Osaka University, Japan, has been used for
in-band flood exposure experiments to test resist sensitivity and
develop photochemical modeling capability. The second, in operation
at SUNY-Albany, integrates exposure/sensitivity with outgassing
measurements (GC/MS and RGA) and also allows direct tests of mirror
contamination, at power densities near those required for Beta
exposure tools. Features of both experiments have been integrated
into a commercial device. Details of this tool -- the Litho Tech
Japan EUVES-7000 system for resist outgassing and exposure -- will be
presented at this meeting.
Traditional Z-Pinch discharge plasma sources designed for EUV applications use electrodes to conduct the high current pulse into the plasma. The contact of these electrodes with the high temperature plasma required for EUV production can cause issues of electrode erosion, electrode spitting and even melting. These can be sources of contaminating debris for any optical system connected to the source. We will present a novel approach to the Z-pinch discharge plasma where the current pulse is induced into the discharge, rather than conducted. The inductive coupling creates magnetic fields which position the resulting electrodeless z-pinch plasma away from the source walls, thereby allowing relatively straightforward approaches to source cooling. We will show results from a commercially available electrodeless z-pinch EUV source that delivers 10 Watts at 13.5nm (±1% bandwidth) into 2π steradians, using xenon as the EUV emitting gas. Source size measurements and the ability to tailor the size to specific applications will be presented. In particular we will report on the optimization of the source for high brightness, for applications such as EUV metrology, microscopy and defect inspection of EUV masks and mask blanks, and the optimization of the source for power output for applications such as resist exposure and resist out-gassing studies. In imaging applications, the illumination optics are often able to reject light except from the immediate region of the pinch. This characteristic has consequences for out-of-band light measurements. We will present out-of-band measurements of light from a highly collimated view of the pinch.