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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/cm2 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.
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