Key sustainability opportunities have been executed in support of corporate initiatives to reduce the environmental footprint and decrease the running cost of DUV light sources. Previously, substantial neon savings were demonstrated over several years through optimized gas management technologies. Beyond this work, Cymer is developing the XLGR 100, a self-contained neon recycling system, to enable minimal gas consumption. The high efficiency results of the XLGR 100 in a production factory are validated in this paper.
Cymer has also developed new light source modules with 33% longer life in an effort to reduce raw and associated resource consumption. In addition, a progress report is included regarding the improvements developed to reduce light source energy consumption.
DUV ArF immersion lithography requires patterning budget improvements in the range of 1/10 nm especially for interconnect layers for advanced process nodes. As every angstrom counts, the Cymer XLR 860ix light source has been developed to deliver the performance required for multiple patterning processes across all sectors: DRAM, 3D NAND, and logic. This paper will describe how imaging margins can be increased by optimizing light source bandwidth settings. Advancements include new hardware and software that enable industry leading bandwidth performance and control. In addition, on-wafer measurements were collected showing the progressive improvements gained with lowering bandwidth on an existing mask.
As system availability is a key enabler for chipmakers, the introduction of this new DUV light source includes improvements that continue to improve productivity by increasing service intervals by >30% while also providing sustainability enhancements.
Multi-patterning techniques with ArF immersion lithography continue to be extended into the 10 and 7 nm nodes. With increasingly challenging process control requirements (CD, overlay, edge placement error), the lithography and patterning tools need to find ways to minimize variation and maintain process margin to achieve high yields. This paper will describe new advances in light source technologies that can regain imaging margins by optimizing light source bandwidth settings in concert with OPC retargeting to take advantage of the contrast improvements1,2 afforded by lower bandwidth. In addition to simulation studies reported previously3,4, on-wafer measurements were collected showing the progressive improvements gained with lowering bandwidth on an existing mask as well as reoptimizing a mask to leverage this lower bandwidth setting. To fully leverage this capability, further improvements in bandwidth stability are going to be featured on a new ArF light source along with an integrated solution that allows the bandwidth target to be commanded by scanner recipe. This will allow lithographers to optimize layers that need further improvements in patterning by using lower bandwidth while continuing to run existing layers with standard, 300 fm bandwidth targets. With the introduction of a new DUV light source, this paper will also describe improvements that continue to reduce running costs in an effort to counteract the escalating costs of multi-patterning lithography.
In response to significant neon supply constraints, Cymer has responded with a multi-part plan to support its customers. Cymer’s primary objective is to ensure that reliable system performance is maintained while minimizing gas consumption. Gas algorithms were optimized to ensure stable performance across all operating conditions.
The Cymer neon support plan contains four elements: 1. Gas reduction program to reduce neon by >50% while maintaining existing performance levels and availability; 2. short-term containment solutions for immediate relief. 3. qualification of additional gas suppliers; and 4. long-term recycling/reclaim opportunity. The Cymer neon reduction program has shown excellent results as demonstrated through the comparison on standard gas use versus the new >50% reduced neon performance for ArF immersion light sources. Testing included stressful conditions such as repetition rate, duty cycle and energy target changes. No performance degradation has been observed over typical gas lives.
Light source technological performance is key to enabling chipmaker yield and production success. Just as important is ensuring that performance is consistent over time to help maintain as high an uptime as possible on litho-cells (scanner and track combination). While it is common to see average tool uptime of over 99% based on service intervention time, we will show that there are opportunities to improve equipment availability through a multifaceted approach that can deliver favorable results and significantly improve on the actual production efficiency of equipment.
The majority of chipmakers are putting light source data generated by tools such as Cymer OnLine (COL), OnPulse Plus, and SmartPulse to good use. These data sets, combined with in-depth knowledge of the equipment, makes it possible to draw powerful conclusions that help increase both chip manufacturing consistency as well as equipment productivity. This discussion will focus on the latter, equipment availability, and how data analysis can help increase equipment availability for Cymer customers.
There are several types of opportunities for increasing equipment availability, but in general we can focus on two primary categories: 1) scheduled downtime and 2) unscheduled downtime. For equipment that is under control of a larger entity, as the laser is to the scanner, there are additional categories related to either communication errors or better synchronization of events that can maximize overall litho-cell efficiency. In this article we will focus on general availability without highlighting the specific cause of litho-cell (laser, scanner and track). The goal is to increase equipment available time with a primary focus is on opportunities to minimize errors and variabilities.
Semiconductor market demand for improved performance at lower cost continues to drive enhancements in excimer light source technologies. Multi-patterning lithography solutions to extend deep-UV (DUV) immersion have driven requirements such as higher throughput and higher efficiencies to maximize the utilization of leading-edge lithography equipment. Three key light source parameters have direct influence on patterning performance – energy, wavelength and bandwidth stability – and they have been the primary areas of continuous improvement. With 14nm node development, a number of studies have shown the direct influence of bandwidth stability on CD uniformity for certain patterns and geometries, leading to the desire for further improvements in this area. More recent studies also examined the impact of bandwidth on 10nm logic node patterning [1]. Alongside these drivers, increasing cost per patterning layer continues to demand further improvements in operating costs and efficiencies from the lithography tools, and the light source can offer further gains in these areas as well. This paper introduces several light source technologies that are embodied in a next-generation light source, the Cymer XLR® 700ix, which is an extension of the ring laser architecture introduced 8 years ago. These technologies enable a significant improvement in bandwidth stability as well as notable reductions in operating costs through more efficient gas management algorithms and lower facilities costs.
Demand for increased semiconductor device performance at low cost continues to drive the requirements for shrinking the geometry of features printed on silicon wafers. Argon fluoride (ArF) excimer laser systems operating at 193 nm and producing high output power played a key role in patterning of the most advanced features for high volume deep ultraviolet (DUV) lithography over the last decade. Lithographic patterning has progressed from ArF dry to ArF immersion (ArFi) to double and multiple patterning applications, with increasingly tight requirements for the quality of light at 193 nm and improved system reliability. This drove the transition from single chamber laser systems to dual chamber systems with ring cavity amplifier architectures. We are presenting a flexible 90-120W ArFi excimer laser system, developed for high volume multiple patterning manufacturing as well as 450mm wafer applications. Light source design is based on dual-chamber architecture with ring cavity power amplifier.
Deep UV (DUV) lithography is being applied to pattern increasingly finer geometries, leading to solutions like double- and multiple-patterning. Such process complexities lead to higher costs due to the increasing number of steps required to produce the desired results. One of the consequences is that the lithography equipment needs to provide higher operating efficiencies to minimize the cost increases, especially for producers of memory devices that experience a rapid decline in sales prices of these products over time. In addition to having introduced higher power 193nm light sources to enable higher throughput, we previously described technologies that also enable: higher tool availability via advanced discharge chamber gas management algorithms; improved process monitoring via enhanced on-board beam metrology; and increased depth of focus (DOF) via light source bandwidth modulation. In this paper we will report on the field performance of these technologies with data that supports the desired improvements in on-wafer performance and operational efficiencies.
Double patterning lithography places significant demands not only on the optical performance of the light source
(higher power, improved parametric stability), but also on high uptime in order to meet the higher throughput
requirements of the litho cell. In this paper, we will describe the challenges faced in delivering improved
performance while achieving better reliability and resultant uptime as embodied in the XLR 600ix light source from
Cymer, announced one year ago. Data from extended life testing at 90W operation will be shown to illustrate these
improvements.
The ability to extend deep ultraviolet (DUV) lithography into the 32 and sub-32nm domain has more recently relied
on improvements in source-mask optimization (SMO), double patterning (DP) and complex, pixellated illumination
patterns. Yet these techniques require a commensurate improvement in the light source that powers the latest
generation scanners in order to enable high performance at high throughput. This paper will show detailed
performance results of the latest-generation light source from Cymer that incorporates flexible power with dramatic
improvements in dose, wavelength and bandwidth stability.
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.
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