|
OPC technique is getting more complicated toward 32nm and below technology node, i.e. from moderate
OPC to aggressive OPC. Also, various types of phase shift mask have been introduced, and then the
manufacturing process of them is complicated now. In order to shorten TAT (Turn around time) time, mask
technique need be considered in addition to lithography technique.
Furthermore, the lens aberration of the exposure system is getting smaller, so the current performance of it is
very close to the ideal. On the other hand, when down sizing goes down to 32nm technology node, it starts to
be reported that there are cases that size cannot be matched between a mask pattern and the corresponding
printed pattern. Therefore, it is very indispensable to understand the pattern sizes correlation between a mask
and the corresponding printed wafer in order to improve the accuracy and the quality, in the situation that the
device size is so small that low k1 lithography had been developed and widely used in a production.
Then it is thought that it is one of the approaches to improve an estimated accuracy of lithography by using
contour that was extracted from mask SEM image in addition to mask model.
This paper describes a newly developed integration system in order to solve issues above, and the applications.
This is a system which integrates CG4500; CD-SEM for mask and CG4000; CD SEM for wafer; using
DesignGauge; OPC evaluation system by Hitachi High-Technologies.
It was investigated that a measurement accuracy improvement by executing a mask-wafer same point
measurement with same measurement algorithm utilizing the new system. At first, we measured patterns
described on a mask and verified the validity based on a measurement value, picture, measurement parameter
and the coordinate. Then create a job file for a wafer CD-SEM using the system so as to measure the same
patterns that were exposed using the mask. In addition, average CD measurement was tried in order to
improve the correlation. Also, in order to estimate very accurate pattern shape, a contour was calculated from a mask SEM image, the
result and the design data was used in a litho simulation. This realizes verification including mask error.
It is thought that it is beneficial for both mask maker and device maker to use this system.
|
