While the industry is making progress to offer EUV lithography schemes to attain ultimate critical dimensions down to 20 nm half pitch, an interim optical lithography solution to address an immediate need for resolution is offered by various integration schemes using advanced PSM (Phase Shift Mask) materials including thin e-beam resist and hard mask. Using the 193nm wavelength to produce 10nm or 7nm patterns requires a range of optimization techniques, including immersion and multiple patterning, which place a heavy demand on photomask technologies. Mask schemes with hard mask certainly help attain better selectivity and hence better resolution but pose integration challenges and defectivity issues. This paper presents a new photomask etch solution for attenuated phase shift masks that offers high selectivity (Cr:Resist > 1.5:1), tighter control on the CD uniformity with a 3sigma value approaching 1 nm and controllable CD bias (5-20 nm) with excellent CD linearity performance (<5 nm) down to the finer resolution. The new system has successfully demonstrated capability to meet the 10 nm node photomask CD requirements without the use of more complicated hard mask phase shift blanks. Significant improvement in post wet clean recovery performance was demonstrated by the use of advanced chamber materials. Examples of CD uniformity, linearity, and minimum feature size, and etch bias performance on 10 nm test site and production mask designs will be shown.
[1]
Tiecheng Zhou,et al.
In situ selectivity monitor for dry etch of photomasks
,
2009,
Photomask Japan.
[2]
Hitoshi Handa,et al.
Practical use of hard mask process to fabricate fine photomasks for 45nm node and beyond
,
2007,
SPIE Photomask Technology.
[3]
Ajay Kumar,et al.
Overcoming mask etch challenges for 45 nm and beyond
,
2008,
European Mask and Lithography Conference.
[4]
Yoshifumi Sakamoto,et al.
Characterization of a new polarity switching negative tone e-beam resist for 14nm and 10nm logic node mask fabrication and beyond
,
2014,
Photomask Technology.