Carl Zeiss SMS has introduced the RegC® process for registration error correction on photomasks. In their PMJ paper, they report using the same femtosecond laser technology as in their previously announced CDC32 product, which corrects CDU error. [The PMJ paper was presented at BACUS, since PMJ was cancelled due to the after-effects of the earthquake and tsunami.]
In these instruments, femtosecond laser pulses create local changes in the refractive index of the photomask substrate (in the case of CDU correction) or bulk strain (in the case of registration error correction). Zeiss claims correction of up to 50% of the total placement error contribution of the photomask.
Zeiss also claims that the treated photomasks are stable. Privately they claim that there is no induced flare. One wonders how this is possible after introducing millions of small pockets of color centers and high strain throughout the exposure field.
[Sorry – I neglected to “Publish” this one last fall. – Richard L]