Laser produced plasma (LPP) systems have been developed as the primary approach for use in EUV scanner light sources for optical imaging of circuit features at 20nm nodes and beyond. This paper provides a review of development progress and productization status for LPP extreme-ultra-violet (EUV) sources with performance goals targeted to meet specific requirements from ASML. We present the latest results on power generation and collector
protection for sources in the field operating at 10W nominal power and in San Diego operating in MOPA (Master Oscillator Power Amplifier) Prepulse mode at higher powers. Semiconductor industry standards for reliability and source availability data are provided. In these proceedings we show results demonstrating validation of MOPA Prepulse operation at high dose-controlled power: 40 W average power with closed-loop active dose control meeting the requirement for dose stability, 55 W average power with closed-loop active dose control, and early collector
protection tests to 4 billion pulses without loss of reflectivity.
Laser produced plasma (LPP) systems have been developed as the primary approach for the EUV scanner
light source for optical imaging of circuit features at sub-22nm and beyond nodes on the ITRS roadmap. This
paper provides a review of development progress and productization status for LPP extreme-ultra-violet
(EUV) sources with performance goals targeted to meet specific requirements from leading scanner
manufacturers. We present the latest results on exposure power generation, collection, and clean transmission
of EUV through the intermediate focus. Semiconductor industry standards for reliability and source
availability data are provided. We report on measurements taken using a 5sr normal incidence collector on a
production system. The lifetime of the collector mirror is a critical parameter in the development of extreme
ultra-violet LPP lithography sources. Deposition of target material as well as sputtering or implantation of
incident particles can reduce the reflectivity of the mirror coating during exposure. Debris mitigation
techniques are used to inhibit damage from occuring, the protection results of these techniques will be shown
over multi-100's of hours.
This paper describes the development of laser-produced-plasma (LPP) extreme-ultraviolet (EUV) source
architecture for advanced lithography applications in high volume manufacturing. EUV lithography is
expected to succeed 193 nm immersion technology for sub-22 nm critical layer patterning. In this paper we
discuss the most recent results from high qualification testing of sources in production. Subsystem
performance will be shown including collector protection, out-of-band (OOB) radiation measurements,
and intermediate-focus (IF) protection as well as experience in system use. This presentation reviews the
experimental results obtained on systems with a focus on the topics most critical for an HVM source.
Laser produced plasma (LPP) systems have been developed as a viable approach for the EUV scanner light sources to
support optical imaging of circuit features at sub-22nm nodes on the ITRS roadmap. This paper provides a review of
development progress and productization status for LPP extreme-ultra-violet (EUV) sources with performance goals
targeted to meet specific requirements from leading scanner manufacturers. The status of first generation High Volume
Manufacturing (HVM) sources in production and at a leading semiconductor device manufacturer is discussed. The
EUV power at intermediate focus is discussed and the lastest data are presented. An electricity consumption model is
described, and our current product roadmap is shown.
Deep ultraviolet (DUV) lithography improvements have been focused on two paths:
further increases in the effective numerical aperture (NA) beyond 1.3, and double
patterning (DP). High-index solutions for increasing the effective NA have not gained
significant momentum due to several technical factors, and have been eclipsed by an
aggressive push to make DP a high-volume manufacturing solution. The challenge is to
develop a cost-effective solution using a process that effectively doubles the lithography
steps required for critical layers, while achieving a higher degree of overlay performance.
As a result, the light source requirements for DP fall into 3 main categories: (a) higher
power to enable higher throughput on the scanner, (b) lower operating costs to offset the
increased number of process steps, and (c) high stability of optical parameters to support
more stringent process requirements. The XLR 600i (6kHz, 90W @15mJ) was
introduced last year to enable DP by leveraging the higher performance and lower
operating costs of the ring architecture XLR 500i (6kHz, 60W @10mJ) platform
currently used for 45nm immersion lithography in production around the world. In
February 2009, the XLR 600ix was introduced as a 60/90W switchable product to
provide flexibility in the transition to higher power requirements as scanner capabilities
are enhanced. The XLR 600ix includes improved optics materials to meet reliability
requirements while operating at higher internal fluences. In this paper we will illustrate
the performance characteristics during extended testing. Examples of performance
include polarization stability, divergence and pointing stability, which enable consistent
pupil fill under extreme illumination conditions, as well as overall thermal stability which
maintains constant beam performance under large changes in laser operating modes.
Furthermore, the unique beam uniformity characteristics that the ring architecture
generates result in lower peak energy densities that are comparable to those of a typical
60W excimer laser. In combination with the XLR's long pulse duration, this allows for
long life scanner optics while operating at 15mJ.
Double patterning (DP) lithography is expected to be deployed at the 32nm node to enable the extension of high NA
(≥1.3) scanner systems currently used for 45nm technology. Increasing the light source power is one approach to address
the intrinsically lower throughput that DP imposes. Improved energy stability also provides a means to improve
throughput by enabling fewer pulses per exposure slit window, which in turn enables the use of higher scanner stage
speeds. Current excimer laser light sources for deep UV immersion lithography are operating with powers as high as
60W at 6 kHz repetition rates. In this paper, we describe the introduction of the XLR 600i, a 6 kHz excimer laser that
produces 90W power, based on a recirculating ring technology. Improved energy stability is inherent to the ring
technology. Key to the successful acceptance of such a higher power, or higher energy laser is the ability to reduce
operating costs. For this reason, the recirculating ring technology provides some unique advantages that cannot be
realized with conventional excimer lasers today. Longer intrinsic pulse durations that develop in the multi-pass ring
architecture reduce the peak power that the optics are subjected to, thereby improving lifetime. The ring architecture also
improves beam uniformity that results in a significantly reduced peak energy density, another key factor in preserving
optics lifetime within the laser as well as in the scanner. Furthermore, in a drive to reduce operating costs while
providing advanced technical capability, the XLR 600i includes an advanced gas control management system that
extends the time between gas refills by a factor of ten, offering a significant improvement in productive time. Finally, the
XLR 600i provides a novel bandwidth stability control system that reduces variability to provide better CD control,
which results in higher wafer yields.
As Argon Fluoride (ArF) lithography moves into high volume production, ArF light sources need to meet performance requirements beyond the traditional drivers of power and bandwidth. The first key requirement is a continuous decrease in Cost of Ownership (CoO) where the industry requirement is for reduction in ArF CoO in line with the historical cost reduction demonstrated for Krypton Fluoride (KrF) light sources. A second requirement is improved light source performance stability. As CD control requirements shrink, following the ITRS roadmap, all process parameters which affect CD variation need tighter control. In the case of the light source, these include improved control of bandwidth, pulse energy stability and wavelength. In particular, CD sensitivity to exposure dose has become a serious challenge for device processing and improvements to laser pulse energy stability can contribute to significantly better dose control.
To meet these performance challenges Cymer has designed a new dual chamber laser architecture. The Recirculating Ring design requires 10X less energy from the Master Oscillator (MO). This new configuration enables the MO chamber lifetime to reach that of the power amplifier chamber at around 30Bp. In addition, other optical modules in the system such as the line narrowing module experience lower light intensity, ensuring even longer optics lifetime. Furthermore, the Recirculating Ring configuration operates in much stronger saturation. MO energy instabilities are reduced by a factor of 9X when passed through the Ring. The output energy stability exhibits the characteristics of a fully saturated amplifier and pulse energy stability improvement of 1.5X is realized. This performance enables higher throughput scanner operation with enhanced dose control. The Recirculating Ring technology will be introduced on the XLR 500i, Cymer's fifth-generation dual chamber-based light source built on the production-proven XLA platform. This paper will describe the design details and performance characteristics of the new laser architecture.
We report on the approach for a high-power high-beam-quality drive laser system that is used for a laser-produced plasma (LPP) EUV source. Cymer has conducted research on a number of solutions for a multi-kW drive laser system that satisfy high volume production requirements. Types of lasers to be presented include XeF at 351 nm and CO2 at 10.6 micron. We report on a high efficiency XeF amplifier with a 3rd harmonic Nd:YLF master oscillator operated in the 6 to 8 kHz range and a CO2 laser system with Q-switched cavity dumped master oscillator and RF pumped fast axial flow amplifiers operated in the 10 to 100 kHz range. CO2 laser short pulse gain and optical isolation techniques are reported. Optical performance data and design features of the drive laser system are discussed, as well as a path to achieve output power scaling to meet high volume manufacturing (HVM) requirements and beyond. Additionally, the electrical efficiency as a component of cost of operation is presented. Development of a drive laser with sufficient output power, high beam quality, and economical cost of operation is critical to the successful implementation of a laser-produced-plasma (LPP) EUV source for HVM applications. Cymer has conducted research on a number of solutions to this critical need. We report our progress on development of a high power system with two gas-discharge power amplifiers to produce high output power with high beam quality. We provide optical performance data and design features of the drive laser as well as a path to output power scaling to meet HVM requirements. Development of a drive laser for LPP EUV source is a challenging task. It requires multi-kW laser output power with short pulse duration and diffraction limited beam quality. In addition, this system needs to be very reliable and cost-efficient to satisfy industry requirements for high volume integrated circuit manufacturing. Feasibility studies of high power laser solutions that utilize proven laser technologies in high power optical gain modules and deliver required beam properties have been performed and are reported.
Development of a drive laser with sufficient output power, high beam quality, and economical cost of consumables is critical to the successful implementation of a laser-produced plasma (LPP) EUV source for HVM applications. Cymer has conducted research on a number of solutions to this critical need. We report our progress on development of a high power system using two gas-discharge power amplifiers and repetition rates exceeding 10 kHz to produce more than 2kW output power with high beam quality. We provide optical performance data and design features of the drive laser as well as a path to output power scaling to meet high volume manufacturing requirements
Since the introduction of the XLA-100 in January 2003, we have built, tested, and shipped a large number of XLA-100 MOPA lasers to microlithography scanner manufacturers. Some systems have already been installed at chip fabrication lines. To ensure product design robustness, we have been performing a long-term system performance test of an XLA-100 laser at Cymer. In this paper, we will report optical performance of the XLA-100 we see during manufacturing final tests, and a summary of the long term testing.
Since the announcement in March 2002 of plans to develop an advanced light source to meet the future spectral power and cost requirements of photolithography, we have made significant progress in the development and productization of the core technology for an ultra line-narrowed, excimer light source based on a master oscillator-power amplifier (MOPA) approach. In this paper, we will focus on the architecture and performance of the first generation of production-ready, MOPA-based ArF light sources developed at Cymer, Inc. This first generation of MOPA-based ArF light sources is referred to as the XLA 100 product series.
Semiconductor chip manufacturing is on the verge of a new production process node driving critical feature sizes below 100 nm. The next generation of 193 nm Argon Fluoride laser, the NanoLithTM 7000, has been developed in response to this recent technology development in the lithography industry. The NanoLithTM 7000, offering 20 Watts average output power at 4 kHz repetition rate, is designed to support the highest exposure tool scan speeds for maximum productivity and wafer throughput. Technology improvements to support the move from pilot production to full production will be described. With core technology defined and performance to specification established, attention turns to cost of operation, which is closely tied to module lifetime and reliability. Here we present results of the NanoLithTM 7000 system lifetest tracking all optical performance data over a 4.4 Billion shot. The system is operated in firing modes ranging from 1-4 kHz, and up to 75% duty cycle. Overall system performance measured to date both in the lab and in the field suggests that this laser meets all the production requirements for 193 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.
We report the performance of a very high repetition rate ArF laser optimized for next generation, high NA, high throughput scanner. The laser's repetition rate exceeds 4kHz, at 5mJ, and at bandwidths of less than 1.2 pm. We discuss the complexity of high power operation, and make some estimates about the robustness of this technology. In particular, we discuss the risks of scaling to this high repetition rate, and prospects of exceeding 4kHz to near 6kHz with 95 percent bandwidths of less than 1pm.
Exposure tools for 193nm lithography are expected to use Argon-Fluoride lasers at repetition rates of at least 2kHz. We are showing that, by revisiting several key technologies, the performance and reliability of ArF lasers at 2 kHz are trending towards a level comparable to KrF lasers.
We describe a coherence filtering technique in the near infrared (IR) based on degenerate four wave mixing (DFWM)
in a Barium Titanate photorefractive crystal and a dye-doped liquid crystal layer. in our experiments, we used a self modelocked
Ti:Sapphire laser and a Q-switched alexandrite laser as light sources. This technique can be used to provide
instantaneous, single-shot, two-dimensional images ofthe internal structure ofmaterials versus depth.
Multi-atmosphere CO2 lasers can provide continuous gain over bands 20 to 30 cm-1 wide in each R and P branch of the 000 yields 100 and 0001 yields 0200 bands, covering approximately 60 percent of the 9.2-10.8 micrometers region. By contrast, the spectrum of a typical low pressure CO2 lasers is 99 percent empty. We describe design studies and the construction of a 20-atmosphere laser that will operate on a single longitudinal model and prove mode-to-mode tunability, thus effecting a useful compromise between the narrow-line capability of a low pressure laser and the broad tunability of a multi-atmosphere laser. One important application of this laser is to pump double-Raman processes in methyl fluoride which will shift the narrow linewidth and tunability to the 150 to 650 micrometers region of the far IR.
We have studied the third-order nonlinearities of Ni(II) and Cu(II) metal-organic complexes in solution using wavelength tunable DFWM experiments in the 550 - 600 nm spectral region associated with d-d transitions introduced by the metal atoms. A room temperature, frequency doubled LiF:F2- color center laser was used as the tunable laser source for these experiments. Additional resonant enhancement over thermally induced nonlinearities is observed for the Cu-based metal-organic complexes in these DFWM studies. Information about the sign of the nonlinearity and relative roles of nonlinear refraction and absorption was obtained with Z-scan experiments. Energy transmission measurements indicated that nonlinear absorption occurs in all samples. Relationships between the nonlinear response and the spectral absorption features of these metal-organics are discussed.
We describe a coherence filtering technique based on degenerate four wave mixing (DFWM) in a thin nonlinear optical material. In contrast to previous works which used ultra-short laser pulses, we performed low-coherence filtering techniques through scattering media with broad- spectrum nanosecond pulses. In our first 'proof of principle' experiments we used a 100 micrometer thick layer of dye solution as a nonlinear optical material and investigated a one dimensional case for depth-resolved measurements through a scattering media consisting of a highly scattering suspension of dielectric microspheres in water. We also describe a technique to obtain instantaneous cross-sectional images (which can be depth scanned to obtain the third dimension) performed with a low-coherence nanosecond laser source on a liquid crystal doped with an infrared dye. Experimental results were obtained with room temperature LiF:F2- and LiF:F2+ color center lasers, and a Q-switched alexandrite laser. This technique can be used to provide instantaneous, single-shot, two-dimensional images of the internal structure of materials versus depth.