Proceedings Article | 11 May 2007
Proc. SPIE. 6607, Photomask and Next-Generation Lithography Mask Technology XIV
KEYWORDS: Photomasks, Chromium, Semiconducting wafers, Printing, Etching, Binary data, Resolution enhancement technologies, Reflectivity, Scanning electron microscopy, Image enhancement
For 45 nm node and beyond, the alternating phase-shift mask (alt. PSM), one of the most expected resolution
enhancement technologies (RET) because of its high image contrast and small mask error enhancement factor (MEEF),
and the binary mask (BIM) attract attention. Reducing CD and registration errors and defect are their critical issues. As
the solution, the new blank for alt. PSM and BIM is developed. The top film of new blank is thin Cr, and the antireflection
film and shielding film composed of MoSi are deposited under the Cr film.
The mask CD performance is evaluated for through pitch, CD linearity, CD uniformity, global loading, resolution and
pattern fidelity, and the blank performance is evaluated for optical density, reflectivity, sheet resistance, flatness and
defect level. It is found that the performance of new blank is equal to or better than that of conventional blank in all
items. The mask CD performance shows significant improvement.
The lithography performance of new blank is confirmed by wafer printing and AIMS measurement. The full dry type
alt. PSM has been used as test plate, and the test results show that new blank can almost meet the specifications of pi-0
CD difference, CD uniformity and process margin for 45 nm node. Additionally, the new blank shows the better pattern
fidelity than that of conventional blank on wafer. AIMS results are almost same as wafer results except for the
narrowest pattern. Considering the result above, this new blank can reduce the mask error factors of alt. PSM and BIM
for 45 nm node and beyond.
