Currently, repair machines used for advanced photomasks utilize principle method like as FIB, AFM, and EB. There
are specific characteristic respectively, thus they have an opportunity to be used in suitable situation. But when it comes
to EUV generation, pattern size is so small highly expected as under 80nm that higher image resolution and repair
accuracy is needed for its machines. Because FIB machine has intrinsic damage problem induced by Ga ion and AFM
machine has critical tip size issue, those machines are basically difficult to be applied for EUV generation.
Consequently, we focused on EB repair tool for research work.
EB repair tool has undergone practical milestone about MoSi based masks. We have applied same process which is
used for MoSi to EUV blank and confirmed its reaction. Then we found some severe problems which show
uncontrollable feature due to its enormously strong reaction between etching gas and absorber material. Though we
could etch opaque defect with conventional method and get the edge shaped straight by top-down SEM viewing, there
were problems like as sidewall undercut or local erosion depending on defect shape. In order to cope with these
problems, the tool vender has developed a new process and reported it through an international conference .
We have evaluated the new process mentioned above in detail. In this paper, we will bring the results of those
evaluations. Several experiments for repair accuracy, process stability, and other items have been done under estimation
of practical condition assuming diversified size and shape defects. A series of actual printability tests will be also
included. On the basis of these experiments, we consider the possibility of EB-repair application for 20nm pattern.