The first NXE3300B systems have been qualified and shipped to customers. The NXE:3300B is ASML’s third generation EUV system and has an NA of 0.33. It succeeds the NXE:3100 system (NA of 0.25), which has allowed customers to gain valuable EUV experience. Good overlay and imaging performance has been shown on the NXE:3300B system in line with 22nm device requirements. Full wafer CDU performance of <1.5nm for 22nm dense and iso lines at a dose of ~16mJ/cm2 has been achieved. Matched machine overlay (NXE to immersion) of around 3.5nm has been demonstrated on multiple systems. Dense lines have been exposed down to 13nm half pitch, and contact holes down to 17nm half pitch. 10nm node Metal-1 layers have been exposed with a DOF of 120nm, and using single spacer assisted double patterning flow a resolution of 9nm has been achieved.
Source power is the major challenge to overcome in order to achieve cost-effectiveness in EUV and enable introduction into High Volume Manufacturing. With the development of the MOPA+prepulse operation of the source, steps in power have been made, and with automated control the sources have been prepared to be used in a preproduction fab environment.
Flexible pupil formation is under development for the NXE:3300B which will extend the usage of the system in HVM, and the resolution for the full system performance can be extended to 16nm. Further improvements in defectivity performance have been made, while in parallel full-scale pellicles are being developed.
In this paper we will discuss the current NXE:3300B performance, its future enhancements and the recent progress in EUV source performance.
All six NXE:3100, 0.25 NA EUV exposure systems are in use at customer sites enabling device development and cycles
of learning for early production work in all lithographic segments; Logic, DRAM, MPU, and FLASH memory. NXE
EUV lithography has demonstrated imaging and overlay performance both at ASML and end-users that supports sub-
27nm device work. Dedicated chuck overlay performance of <2nm has been shown on all six NXE:3100 systems.
The key remaining challenge is productivity, which translates to a cost-effective introduction of EUVL in high-volume
manufacturing (HVM). High volume manufacturing of the devices and processes in development is expected to be done
with the third generation EUV scanners - the NXE:3300B. The NXE:3300B utilizes an NA of 0.33 and is positioned at a
resolution of 22nm which can be extended to 18nm with off-axis illumination. The subsystem performance is improved
to support these imaging resolutions and overall productivity enhancements are integrated into the NXE platform
consistent with 125 wph. Since EUV reticles currently do not use a pellicle, special attention is given to reticle-addeddefects
performance in terms of system design and machine build including maintenance procedures.
In this paper we will summarize key lithographic performance of the NXE:3100 and the NXE:3300B, the NXE platform
improvements made from learning on NXE:3100 and the Alpha Demo Tool, current status of EUV sources and
development for the high-power sources needed for HVM.
Finally, the possibilities for EUV roadmap extension will be reviewed.
Shipping in 2013, the NXE:3300 is the second generation of ASML’s EUV exposure platform. We review the current
status of EUV optics production for the NXE:3300 tools. Four customer systems of the StarlithTM3300 series have been delivered so far. These sets of optics are characterized by a numerical aperture of 0.33 as well as significantly lower flare and wave-front levels compared to the StarlithTM3100. Meanwhile imaging down to 14 nm node features was demonstrated with the StarlithTM3300 pilot optics. Starting with this generation we introduce a fully new illumination system which allows for setting changes without efficiency loss. In this paper we focus on mirror fabrication and at wavelength qualification results of the optical systems produced so far. We also give an outline of potential solutions for the next generation of EUVL optics using higher NA.
ASML's NXE platform is a multi-generation TWINSCAN™ platform using an exposure wavelength of 13.5nm,
featuring a plasma source, all-reflective optics, and dual stages operating in vacuum. The NXE:3100 is the first product
of this NXE platform. With a 0.25 NA projection optics, a planned throughput of 60 wafers/hr and dedicated chuck
overlay of 4 nm, the NXE:3100 is targeted for extreme ultraviolet lithography (EUVL) implementation at 27nm halfpitch
(hp) and below. The next generation NXE tools utilize a 0.33NA lens and include off-axis illumination for high
volume manufacturing at a resolution down to 16nm hp and a targeted throughput of >100 wafers/hr. We share details
of the performance of the 0.25NA lithography products in terms of imaging, overlay, throughput, and defectivity. We
will show that we have met the required imaging performance associated with the 27nm hp node. We will also include a
summary of the EUV source development, which is a key enabler for cost-effective introduction of EUVL into highvolume
manufacturing. Finally, we will highlight some of the technical changes we introduced to enable the transition
from 27 to 22nm lithographic performance while introducing our 0.33NA Step & Scan system, the NXE:3300B.
With the 1st NXE:3100 being operational at a Semiconductor Manufacturer and a 2nd system being shipped at the time of
writing this paper, we enter the next phase in the implementation of EUV Lithography. Since 2006 process and early
device verification has been done using the two Alpha Demo Tools (ADT's) located at IMEC in Leuven, Belgium and at
the CSNE in Albany, New York, USA. Now process integration has started at actual Chipmakers sites. This is a major
step for the development and implementation of EUVL. The focus is now on the integration of exposure tools into a
manufacturing flow, preparing high volume manufacturing expected to start in 2013.
While last year's NXE:3100 paper focused on module performance including optics, leveling and stages, this years
update will, in detail, assess imaging, overlay and productivity performance. Based on data obtained during the
integration phase of the NXE:3100 we will assess the readiness of the system for process integration at 27nm hp and
below. Imaging performance with both conventional and off-axis illumination will be evaluated. Although single
exposure processes offer some relief, overlay requirements continue to be challenging for exposure tools. We will share
the status of the overlay performance of the NXE:3100. Source power is a key element in reaching the productivity of
the NXE:3100 - its status will be discussed as well.
Looking forward to high volume manufacturing with EUV we will update on the design status of the NXE:3300B being
introduced in 2012 with a productivity target of 125wph. Featuring a 0.33NA lens and off-axis illumination at full
transmission, a half pitch resolution from 22nm to 16nm can be supported. In order to ensure a solid volume ramp-up the
NXE:3300B will be built on as many building blocks from the NXE:3100 as possible making optimum use of the NXE
The NXE platform is a multi-generation EUV production platform that builds the technology, design and experience of
both TWINSCAN™ and the two 0.25NA EUV tools (Alpha Demo Tools or ADT's) in use at two research centers for
EUV process development. This paper reviews the EUV Industry status, presents recent imaging and device work carried
out on the two 0.25NA ADT EUV tools and the status of the 1st production tool. Shipping in 2010, the NXE:3100 will be
the 1st generation of the EUV exposure platform. With an NA of 0.25 and a productivity of 60wph this tool is targeted
for EUV process implementation and early volume production at the 27nm node. We will highlight the key features of
the NXE:3100. On our way towards shipment we describe the manufacturing status and performance data of optics,
source and stages. The 0.32NA 2nd generation tool is designed as a lithography solution for high volume manufacturing
with EUV at the 22nm node and below. With a productivity >125wph the NXE:3300 will be a cost effective solution for
Lithography at the 22nm node and below. A 3rd generation with off-axis illumination at full transmission ensures
extendibility of the NXE:3300 for resolutions down to 16nm.
In 2005, Carl Zeiss SMT AG has shipped two sets of Optics for ASML's Alpha Demo Tools. This was the starting point
for the introduction of full field EUV systems. Meanwhile imaging down to 25 nm was demonstrated with the ADT
tools. Based on the learning from these tools ASML has built the NXE platform - a multi-generation EUV production
platform. Shipping in 2010, the NXE:3100 will be the first generation of the EUV exposure platform. We review the
current status of EUV optics production for the NXE:3100 tools.
Four optical systems of the 3100 series have been shipped so far. These sets of optics are characterized by significantly
lower flare and wave-front levels compared to the ADT. In addition a new illumination system with higher partial
coherence has been developed. In this paper we focus on mirror fabrication and at wavelength qualification results of the
optical systems produced so far.
We also will give an outline of the next generation, a 0.32NA exposure tool including EUVL off-axis illumination for
resolutions down to 16nm. We take the expected imaging requirements as a starting point and compare it with the current
status of our technology development. A brief overview for further tool extensions by higher NA will be given as well.
Cost, cost, cost: that is what it is - ultimately - all about. Single exposure lithography is the most cost effective means of
achieving critical level exposures, and extreme ultraviolet lithography (EUVL) is the only technology that will enable
this for ≤ 27nm production. ASML is actively engaged in the development of a multi-generation production EUVL
system platform that builds on TWINSCANTM technology and the designs and experience gained from the Alpha Demo
Tools (ADTs). The ADTs are full field step-and-scan exposure systems for EUVL and are being used at two research centers for EUVL process development by more than 10 of the major semiconductor chip makers, along with all major suppliers of masks and resist. Recently, successful implementation of EUVL for the contact hole and metal layer was demonstrated in the world's smallest (0.099 μm2) electrically functional 22nm CMOS SRAM device .
We will highlight the key features of the system description for the production platform, including the manufacturing
status of projection lens, illuminator optics, and source. Experimental results from ADT showing the progress in imaging
and resist work will be covered as well - a snapshot of imaging data can be seen in the figure below.
We will share our vision on the extendability of EUVL by discussing our system implementation roadmap. We will
explain our approach for multiple tool generations on a single platform, highlighting the ways to support the technology
nodes from 27nm half-pitch with a 0.25NA lens going down to below 16nm with a 0.32NA lens.
We derive an imaging budget from the performance of extreme ultraviolet (EUV) optics with NA = 0.32, and demonstrate that the requirements for 22-nm applications are met. Based on aerial image simulations, we analyze the impact of all relevant contributors, ranging from conventional quantities like straylight or aberrations, to EUV-specific topics, namely the influence of 3-D mask effects and faceted illumination pupils. As test structures we consider dense to isolated lines, contact holes, and 2-D elbows. We classify the contributions in a hierarchical order according to their weight in the critical dimension uniformity (CDU) budget and identify the main drivers. The underlying physical mechanisms causing different contributions to be critical or less significant are clarified. Finally, we give an outlook for the 16- and 11-nm nodes. Future developments in optics manufacturing will keep the budgets controlled, thereby paving the way to enable printing of these upcoming nodes.
We derive an imaging budget from the performance of EUV optics with NA = 0.32, and demonstrate that the
22nm node requirements are met. Based on aerial image simulations, we analyze the impact of all relevant
contributors, ranging from conventional quantities, like straylight or aberrations, to EUV-specific topics, namely
influence of 3D mask effects and facetted illumination pupils. As test structures we consider dense to isolated
lines, contact holes, and 2D elbows. We classify the contributions in a hierarchical order according to their
weight in the CDU budget and identify the main drivers. The underlying physical mechanisms causing different
contributions to be critical or less significant are clarified. Finally, we give an outlook for the 16nm and 11nm
nodes. Future developments in optics manufacturing will keep the budgets controlled, thereby paving the way
to enable printing of these upcoming nodes.
Single exposure lithography is the most cost effective means of achieving critical level exposures, and extreme
ultraviolet lithography (EUVL) is the technology that will enable this for 27nm production and below. ASML is actively
engaged in the development of a multi generation production EUVL system platform that builds on TWINSCANTM
technology and the designs and experience gained from the build, maintenance, and use of the Alpha Demo Tools
(ADTs). The ADTs are full field step-and-scan exposure systems for EUVL and are being used at two research centers
for EUVL process development by more than 10 of the major semiconductor chip makers, along with all major suppliers
of masks and resist. In this paper, we will present our EUVL roadmap, and the manufacturing status of the projection
lens for our first production system. Included will also be some test data on the new reticle pods. Experimental results
from ADT showing the progress in imaging (28 nm half pitch 1:1 lines/spaces CDU ~10%), single machine overlay
down to 3 nm, and resist complete the paper.
The ASML extreme ultraviolet lithography (EUV) alpha demo tool is a 0.25NA fully functional lithography tool with a
field size of 26×33 mm2, enabling process development for sub-40-nm technology. Two exposure tools are installed at
customer facilities, and are equipped with a Sn discharge source. In this paper we present data measured at intermediate
focus of the Sn source-collector module. We also present performance data from both exposure tools, show the latest
results of resist exposures including excellent 32-nm half pitch dense staggered and aligned contact hole images, and
present the highlights of the first demonstration of an electrically functional full field device with one of the layers made
using EUVL in ASML's alpha demo tool.
ASML has built and shipped to The College of Nanoscale Science and Engineering of the University at Albany (CNSE)
and IMEC two full field step-and-scan exposure tools for extreme ultraviolet lithography. These tools, known as Alpha
Demo Tools (ADT), will be used for process development and to set the foundation for the commercialization of this
technology. In this paper we will present results from the set-up and integration of both ADT systems, status of resist
and reticles for EUV, and the plans for using these tools at the two research centers. We will also present the first resist
images from one of the tools at the customer site, and demonstrate 32nm half-pitch dense lines/spaces printing as well as
32nm dense contact hole printing.
This work discusses the imaging properties of EUVL systems on the basis of an aerial image study in resist. A process window analysis for the lithographic structures which are driving the ITRS roadmap is presented. Here we cover the 45 nm and 32 nm node. In a first step we focus on the contribution of wavefront aberrations and flare effects to the imaging performance. In a second step we investigate the process latitude for different generic pattern of the above mentioned nodes. It becomes clear that EUVL tools are a very good choice for the printing of contact holes. Dense and semi-dense lines can be easily printed too, using a conventional illumination setting. From our current perspective, isolated features on bright field reticles are the most challenging structures for EUV imaging due to the flare impact on contrast and process latitude. Related to flare we discuss our progress in mirror surface manufacturing to reduce the overall flare level.
This paper presents a comprehensive study of the impact of wavefront errors on low-k1-imaging performance using high numerical aperture NA lithographic systems. In particular, we introduce a linear model that correctly describes the aberration induced imaging effects. This model allows us to quantify the aberration requirements for future lithographic nodes. Moreover, we derive scaling laws characterizing the imaging performance in dependence on the key parameters exposure wavelength λ, NA, and k1. Our investigations demonstrate, first, that an accurate control of coma is and will be crucial, and, second, that spherical requirements will be very tight for k1<0.3 due to isolated contact printing. Finally, we summarize the results of this paper in a roadmap covering the aberration requirements in optical lithography down to the 45nm node. We conclude that the improvement of wavefront quality is necessary to enable imaging enhancement techniques, but is not sufficient to replace these techniques.
This study assesses the various approaches to printing contacts in the sub 100nm regime using 193nm. Traditional techniques are analyzed along with the use of tri-tone contacts and pupil filtering. Approaches using attPSM masks looks promising down to pitches of 300nm. Below this, assist features may be needed to prevent residual artifacts due to sidelobes. For pitches > 400nm the use of tri-tone masks show a significant improvement in process latitude and ease of overlapping process windows. The pupil filter solution does not seem provide any significant improvement as compared to other solutions with the exception that it provides the lower MEF. Realization of this solution will increase machine complexity and will possibly impact throughput, especially if using transmission filters. However, pupil filtering can be an option for isolated contact layers that are printed with binary masks. We find that the process and enhancement techniques to print a dense contacts and isolated contacts to be vastly different. This may require a split into two exposures if an extensive pitch range is needed.
This paper reports on the self-assembled growth of II-VI semiconductor quantum dots by molecular beam epitaxy. The dots are formed in a highly-strained (Zn,Cd)Se film of only a few monolayer width grown on ZnSe. The formation sets on when the CD mole fraction exceeds 30 percent. We present data on the recombination and relaxation of carriers and excitons in these zero-dimensional structures as well as their interaction with phonons.
This paper studies excitons and bi-excitons in ternary (Zn,Cd)Se/ZnSe quantum wells, widely used as active region in blue-green laser diodes. Localization on alloy disorder characteristically influences the electronic structure of these excitations and their dynamical behavior. The low-temperature lasing is controlled by bi-excitons. Gain as large as 2 (DOT) 104 cm-1 and optical threshold densities as low as 2 kW cm-2 are observed. Due to their localization-enhanced binding energy, bi-exciton signatures are present up to 150 K.