The current industry plan is for EUV Lithography (EUVL) to enter High Volume Manufacturing (HVM) in the 2019/20
timeframe for the 1X nm half-pitch (HP) node (logic and memory). Reticle quality and reticle defects continue to be a top
industry risk. The primary reticle defect quality requirement continues to be “no reticle defects causing 10% or larger CD
errors on wafer (CDE)”. In 2013, KLA-Tencor reported on inspection of EUV reticles using a 193nm wavelength
inspection system1. The report included both die-to-database (db) and die-to-die (dd) inspection modes. Results showed
the capability to detect a wide variety of programmed and native reticle defects judged to be critical. We have developed
extensions to the 193nm wavelength (193) inspection system for the typical 2019/20 HVM EUV reticle defect
requirements. These improvements include innovations in: defect enhancement methods, database modeling, defect
detection, and throughput. In this paper, we report on the latest data and results of this work, focusing on EUV reticle dieto-
database inspection. Inspection results are shown using typical next generation EUV programmed defect test reticles
and typical full field product-like EUV reticles, all from industry sources. Results show significant defect detection
improvements versus the prior generation inspection system. We also report the test results of a high throughput die-todatabase
inspection mode that could be used for the typical mask shop outgoing inspection of EUV reticles where particles
are the primary defect to be detected and there is no pellicle (or the pellicle transmits 193nm wavelength<sup>2</sup>).
The prevailing industry opinion is that EUV Lithography (EUVL) will enter High Volume Manufacturing (HVM) in the
2015 – 2017 timeframe at the 16nm HP node. Every year the industry assesses the key risk factors for introducing EUVL
into HVM – blank and reticle defects are among the top items.
To reduce EUV blank and reticle defect levels, high sensitivity inspection is needed. To address this EUV inspection
need, KLA-Tencor first developed EUV blank inspection and EUV reticle inspection capability for their 193nm
wavelength reticle inspection system – the Teron 610 Series (2010). This system has become the industry standard for
22nm / 3xhp optical reticle HVM along with 14nm / 2xhp optical pilot production; it is further widely used for EUV
blank and reticle inspection in R and D.
To prepare for the upcoming 10nm / 1xhp generation, KLA-Tencor has developed the Teron 630 Series reticle inspection
system which includes many technical advances; these advances can be applied to both EUV and optical reticles. The
advanced capabilities are described in this paper with application to EUV die-to-database and die-to-die inspection for
currently available 14nm / 2xhp generation EUV reticles.
As 10nm / 1xhp generation optical and EUV reticles become available later in 2013, the system will be tested to identify
areas for further improvement with the goal to be ready for pilot lines in early 2015.
This paper assesses the readiness of EUV masks for pilot line production. The printability
of well characterized reticle defects, with particular emphasis on those reticle defects that
cause electrical errors on wafer test chips, is investigated. The reticles are equipped with
test marks that are inspected in a die-to-die mode (using DUV inspection tool) and
reviewed (using a SEM tool), and which also comprise electrically testable patterns. The
reticles have three modules comprising features with 32 nm ground rules in 104 nm pitch,
22 nm ground rules with 80 nm pitch, and 16 nm ground rules with 56 nm pitch (on the
wafer scale). In order to determine whether specific defects originate from the substrate,
the multilayer film, the absorber stack, or from the patterning process, the reticles were
inspected after each fabrication step. Following fabrication, the reticles were used to print
wafers on a 0.25 NA full-field ASML EUV exposure tool. The printed wafers were
inspected with state of the art bright-field and Deep UV inspection tools. It is observed
that the printability of EUV mask defects down to a pitch of 56 nm shows a trend of
increased printability as the pitch of the printed pattern gets smaller - a well established
trend at larger pitches of 80 nm and 104 nm, respectively. The sensitivity of state-of-the-art
reticle inspection tools is greatly improved over that of the previous generation of
tools. There appears to be no apparent decline in the sensitivity of these state-of-the-art
reticle inspection tools for higher density (smaller) patterns on the mask, even down to
56nm pitch (1x). Preliminary results indicate that a blank defect density of the order of
0.25 defects/cm<sup>2</sup> can support very early learning on EUV pilot line production at the 16nm node.
As optical lithography progresses towards 32nm node and beyond, shrinking feature size on photomasks and growing
database size provides new challenges for reticle manufacture and inspection. The new TeraScanXR extends the
inspection capability and sensitivity of the TeraScanHR to meet these challenges. TeraScanXR launches a new function
that can dynamically adjust defect sensitivities based on the image contrast (MEEF) -- applying higher sensitivity to
dense pattern regions, and lower sensitivity to sparse regions which are lithographically less significant. The defect
sensitivity of TeraScanXR for Die-to-Die (DD) and Die-to-Database (DDB) inspection mode is improved by 20-30%,
compared with TeraScanHR. In addition, a new capability is introduced to increase sensitivity specifically to long CD
defects. Without sacrificing the inspection performance, the new TeraScanXR boosts the inspection throughput by 35%-
75% (depending upon the inspection mode) and the dataprep speed by 6X, as well as the capability to process 0.5-1
Terabyte preps for DDB inspection.
A prototype die-to-database high-resolution reticle defect inspection system has been developed for 32nm and below
logic reticles, and 4X Half Pitch (HP) production and 3X HP development memory reticles. These nodes will use
predominantly 193nm immersion lithography (with some layers double patterned), although EUV may also be used.
Many different reticle types may be used for these generations including: binary (COG, EAPSM), simple tritone,
complex tritone, high transmission, dark field alternating (APSM), mask enhancer, CPL, and EUV. Finally, aggressive
model based OPC is typically used, which includes many small structures such as jogs, serifs, and SRAF (sub-resolution
assist features), accompanied by very small gaps between adjacent structures. The architecture and performance of the
prototype inspection system is described. This system is designed to inspect the aforementioned reticle types in die-todatabase
mode. Die-to-database inspection results are shown on standard programmed defect test reticles, as well as
advanced 32nm logic, and 4X HP and 3X HP memory reticles from industry sources. Direct comparisons with currentgeneration
inspection systems show measurable sensitivity improvement and a reduction in false detections.
KEYWORDS: Signal to noise ratio, Reticles, Defect detection, Detection and tracking algorithms, Spatial frequencies, Sensors, Image processing, Inspection, Modulation transfer functions, Line edge roughness
The new TeraScanXR reticle inspection system extends the capability of the previous TeraScanHR platform to advanced
32nm logic and 40nm Half Pitch (HP) memory technology nodes. The TeraScanXR has been designed to provide a
significant improvement in image quality, defect sensitivity and throughput relative to the HR platform. Defect
sensitivity is increased via a combination of improved Die-to-Die (D:D) and Die-to-Database (D:DB) algorithms, as well
as enhancements to the image auto-focus (IAF). Modifications to system optics and the introduction of a more powerful
image processing computer have enabled a ~2X faster inspection mode. In this paper, we describe the key features of the
TeraScanXR platform and present preliminary data that illustrate the capability of this tool. TeraScanHR tools currently
at customer sites are field-upgradeable to the TeraScanXR configuration.
The slow progress of the 157nm-F<sub>2</sub> laser exposure tool development results in broad adaptation of high numerical aperture (NA>0.8) 193nm-ArF lithography for the 65nm-node production solution. This decision, however, forces lithographers to increase dependency on very aggressive RET technologies. This in turn demands mask making capabilities the industry has never faced before such as 100nm (@4X on mask scale) size Sub Resolution Assist Features (SRAF). This report covers our early work on our mask making capability development for the 65nm-node process technology development cycle for production in 2005. Our report includes the 65nm node mask technology capability development status for mask CD and registration dimensions control, current inspection capability/issues and development efforts for critical layer masks with aggressive RET (especially of EAPSM with SRAF).
A new die-to-database reticle inspection system has been developed to meet the production requirements for 130nm node 4x reticles, as well as, the early inspection requirements for 100nm node 4x reticles. This new system is based on the TeraStar platform<SUP>1</SUP> developed recently by KLA-Tencor Corporation for high performance die-to-die and STARlight inspection of 130nm node reticles. The TeraStar platform uses high-NA triple-beam scanning laser optics for high throughput. The platform also includes a new generation of defect detection algorithms and image processing hardware to inspect, with high sensitivity and low false detections, the small linewidths, aggressive OPC, and advanced EPSM 4x reticles characteristic of the 130nm node. The platform further includes the TeraPro concurrent STARlight and die- to-die inspection mode for exceptional productivity. The necessary database elements have now been developed and added to the TeraStar platform, to give it die-to-database inspection capability. A new data format along with new data preparation, data rendering, and data modeling algorithms have been developed to allow high precision database matching with the optical image for exceptional die-to- database performance. The TeraPro high productivity features of the TeraStar platform have been extended to the die-to- database mode providing the opportunity to use STARlight and die-to-database modes concurrently. The system design and in-house test results are discussed.
A new die-to-database reticle inspection system has been developed to meet the production requirements for 130nm node 4x reticles, as well as, the early inspection requirements for 100nm node 4x reticles. This new system is based on the TeraStarT platform1 developed recently by KLA-Tencor Corporation for high performance die-to-die and STARlightT inspection of 130nm node reticles. The TeraStar platform uses high-NA triple-beam scanning laser optics for high throughput. The platform also includes a new generation of defect detection algorithms and image processing hardware to inspect, with high sensitivity and low false detections, the small linewidths, aggressive OPC, and advanced EPSM 4x reticles characteristic of the 130nm node. The platform further includes the TeraProTM concurrent STARlight and die-to-die inspection mode for exceptional productivity. The necessary database elements have now been developed and added to the TeraStar platform, to give it die-to-database inspection capability. A new data format along with new data preparation, data rendering, and data modeling algorithms have been developed to allow high precision database matching with the optical image for exceptional die-to-database performance. The TeraPro high productivity features of the TeraStar platform have been extended to the die-to-database mode providing the opportunity to use STARlight and die-to-database modes concurrently.
Elimination of photomask defects requires identifying the sources of contaminants at each process step. Current industry practice is to perform defect inspection at the end of processing. This makes determining the source of defect generators extremely difficult. This paper presents data taken from inspections performed immediately following the principal processing steps done in photomask manufacture. The KLA-Tencor SLF27 TeraStar™ inspection tool was used to inspect a generic test pattern after developing, etching and stripping of the resist.