Significant progress has been made over the past several years in developing extreme ultraviolet (EUV) mask
infrastructure, especially in EUV reticle handling and protection. Today, the industry has converged to standardize the
dual pod reticle carrier approach in developing EUV reticle handling solutions. SEMATECH has already established
reticle handling infrastructure compliant with industry's draft standard, including carrier, robotic carrier handling,
automated carrier cleaning, vacuum protection, and state-of-the-art particulate contamination testing capabilities. It
proves to be one of the key enablers in developing EUV reticle protection solutions, through broad collaboration with
industry stakeholders and suppliers. In this paper, we discuss our in-house reticle handling infrastructure and provide
insights on how to apply it in EUV lithography pilot line development and future production line. We present particulate
contamination free baseline results of state-of-the-art EUV reticle carriers, i.e., sPod, throughout lifecycle uses. We will
also compare the results against requirements for 32 nm half-pitch (HP) EUV lithography, to identify the remaining
challenges ahead of the industry.
Successful commercialization of extreme ultraviolet lithography (EUVL) requires high quality EUV mask blanks for
patterned masks that are essentially defect-free and very flat with high performance reflective multilayers. For 32 nm
half-pitch (HP) integrated circuit manufacturing, such blanks require zero defects down to 25 nm diameter sizes while
simultaneously meeting other specifications. At least three critical specifications that need continued improvements
(total defects, defect size inspection, and substrate flatness control) are challenging to attain individually; meeting all
requirements simultaneously will be especially challenging. Since early 2003, SEMATECH has been engaged with the
mask blank materials and mask tool supplier community to drive the readiness of alpha, beta, and production mask
blanks to support EUV lithography introduction. SEMATECH uses its commercial mask blank development roadmap
together with neutral metrology evaluations of commercial suppliers' materials to monitor progress against needed
production requirements. Commercial blank capability has improved significantly over the past two years; however,
beta-level performance has still not been attained for all requirements. Attaining integrated blank specifications is more
difficult than meeting individual specifications. Significant improvements including defectivity, flatness, coefficient of
thermal expansion (CTE), reflectivity, wavelength control, and buffer/absorber stack performances are needed. Several
orders of magnitude improvement is needed in defectivity levels alone coupled with increased detection sensitivity to 25
nm diameter defects. This paper will illustrate the recent rate of improvements along with an updated SEMATECH
commercial roadmap, highlighting individual specification performances and total blank integrated performance levels
currently better than 0.2 def/cm<sup>2</sup> at ≥ 80 nm polystyrene latex (PSL), peak reflectivity ≥ 64.0%, substrate flatnesses ≤ 175 nm peak-to-valley (P-V), with other key requirements. EUV blank cost of ownership studies will highlight the
cost to manufacture these materials and show potential issues if yields are marginal.
Excellent progress has been made over the past years in meeting the demanding specifications for commercial extreme
ultraviolet (EUV) mask blanks. But as EUV technology is being prepared for pilot-line introduction later this decade, a
substantial effort is still required in many EUV mask infrastructure areas. These include defect inspection, reticlehandling
standardization, substrate and mask flatness, and resulting overall mask cost of ownership (CoO). Defect
inspection metrology for finding printable defects of < 30 nm polystyrene latex (PSL) size is a key EUV mask
infrastructure enabler. To meet EUV mask blank production specifications for 32 nm half-pitch (hp) manufacturing, a
next generation EUV mask blank inspection technology will be needed in 2-3 years. The industry must soon adopt
standards for EUV reticle handling including carrier and loadport solutions for unified requirements to support
commercial pilot-line and production tool developments. The stringent mask substrate flatness specification will be very
difficult to meet and is likely to significantly increase overall EUV mask cost. The industry needs to correct for nonflatness
at the various stages of a mask life cycle and must develop respective standards and specifications to determine
what kind of non-flatness can be corrected. For EUV lithography to be successful, it must be affordable. Lower EUV
mask costs have been a key advantage for EUV compared to optical mask extensions. To maintain this advantage, mask
manufacturing and metrology methods while supporting aggressive mask specifications must remain cost competitive.
In extreme ultraviolet lithography (EUVL), the lack of a suitable material to build conventional pellicles calls for
industry standardization of new techniques for protection and handling throughout the reticle's lifetime. This includes
reticle shipping, robotic handling, in-fab transport, storage, and uses in atmospheric environments for metrology and
vacuum environments for EUV exposure. In this paper, we review the status of the industry-wide progress in developing
EUVL reticle-handling solutions. We show the industry's leading reticle carrier approaches for particle-free protection,
such as improvements in conventional single carrier designs and new EUVL-specific carrier concepts, including
variations on a removable pellicle. Our test indicates dual pod approach of the removable pellicle led to nearly particle-free
use during a simulated life cycle, at ~50nm inspection sensitivity. We will provide an assessment of the remaining
technical challenges facing EUVL reticle-handling technology. Finally, we will review the progress of the SEMI EUVL
Reticle-handling Task Force in its efforts to standardize a final EUV reticle protection and handling solution.
We report the actinic (EUV wavelength) and non-actinic inspection of a multilayer-coated mask blank containing an
array of open-field defect repair sites created in different ways. The comparison of actinic brightfield and darkfield
measurements shows the importance of having both local reflectivity and scattering measurements. Although effective
mask blank repair capabilities have not been adequately demonstrated, the data acquired in this experiment have been
very instructive. Correlation with non-actinic inspection methods shows the difficulty of establishing a successful predictive
model of the EUV response without EUV cross-comparison. The defect repair sites were also evaluated with SEM,
AFM, and 488-nm-wavelength confocal microscopy. The data raise important questions about mask quality specifications
and the requirements of future commercial actinic inspection tools.
For successful commercialization of Extreme Ultraviolet (EUV) lithography essentially defect free mask blanks are required by 2009 for the 45nm Half Pitch (HP). SEMATECH has been engaging with the mask blank materials and tool supplier community for several years and has evaluated rates of improvements against the needed alpha, beta, and production performance levels required to support EUV lithography introduction in 2009. Significant improvements in many performance levels must be achieved with simultaneous specifications including defectivity, reflectivity, wavelength control, and buffer / absorber stack performances. Although some commercial capability exists today for limited "alpha" level grade blank materials there are several orders of magnitude improvement needed in defectivity levels coupled with defect size detection sensitivity. Although coordinated regional development programs for mask blanks have high effort levels rapid improvements are required to meet the 45nm HP timing in 2009 that is just 5 short years away. Traditional supplier rates of improvements may not be enough to meet the need by 2009. This paper will illustrate the general rate of improvements and further developments or innovative solutions that may be needed in several areas. The SEMATECH EUV mask blank development roadmap will be reviewed with SEMATECH's perspective of commercial readiness predictions by 2009.
International SEMATECH (ISMT) established a program in 1996 to narrow the Next Generation Lithography (NGL) options on the SIA Roadmap through a global consensus process. Methodologies developed by the SIA Lithography Technical Working Group (TWG) were adopted to ensure a balanced and objective assessment. Critical reviews with emphasis on technical program plans, solutions to critical issues (showstoppers), error budget analysis, cost-of-ownership, business plans, and schedules were implemented with the Technical Champions of each technology. White papers were written by the Technical Champion teams to better educate the participants in the annual worldwide NGL workshops. Participants made their recommendations through a survey conducted at the end of each workshop. A Task Force of the key stakeholders from global chip makers, equipment suppliers and consortia was commissioned to review the workshop output, assess the progress on the critical issues and make recommendations to ISMT on narrowing the options. As a result of this global consensus process and the critical issue projects, the NGL Task Force has made the following recommendations: (i) November 1997 - Massively Parallel Direct Write (MPDW) is not mature enough for introduction until at least the 50nm node. (ii) December 1998 - ISMT should narrow its support to two options EUVL and EPL, and that other worldwide activity on X-Ray and IPL continue. (iii) December 1999 - ISMT should continue its support for EUVL and EPL for the 70nm node, it also recognized the growing possibility that the industry might need more than one mainstream technology for the diverging application of DRAM/MPU and ASIC/SOC. (iv) September 2000 - The industry in general should narrow its support for commercialization to EUVL and EPL for insertion at the 70nm node. (v) August 2001 - The industry should continue to fund the commercialization of both EUVL and EPL. Today, the ISMT program for NGL is transitioning from option selection to promoting critical issues solutions and commercial infrastructure for EUVL with initial focus on mask blanks. ISMT is also pursuing collaboration with the suppliers and consortia developing EPL technology to provide stable stencil mask for contact layers. This paper describes the evolution of the program, results of the year 2001 activities, and the plans for 2002.
As technology advances, becoming more difficult and more expensive, the cost of ownership (CoO) metric becomes increasingly important in evaluating technical strategies. The International SEMATECH CoC analysis has steadily gained visibility over the past year, as it attempts to level the playing field between technology choices, and create a fair relative comparison. In order to predict mask cots for advanced lithography, mask process flows are modeled using bets-known processing strategies, equipment cost, and yields. Using a newly revised yield mode, and updated mask manufacture flows, representative mask flows can be built. These flows are then used to calculate mask costs for advanced lithography down to the 50 nm node. It is never the goal of this type of work to provide absolute cost estimates for business planning purposes. However, the combination of a quantifiable yield model with a clearly defined set of mask processing flows and a cost model based upon them serves as an excellent starting point for cost driver analysis and process flow discussion.