In this presentation, the advantage in the use of combination of polarized illumination and technique of
optimum shape mask for contact-hole lithography will be discussed. Both simulation and experimental work were
carried out to characterize performance of this technique. We confirmed that some polarized illuminations show
improvement in image contrast, MEEF, and DOF for nested contact-hole than non-polarized condition. In addition,
certain shape mask shows more improvement. Totally 63% DOF improvement from traditional square shape with nonpolarized
condition was confirmed. In final single exposure era for contact-hole, this result with techniques of hybrid
mask shape and polarized illumination is very attractive.
There has been an ongoing request to make semiconductor devices smaller and smaller. The cellblock size
of SRAM is predominated by both a gate-to-contact space and a poly-to-poly space. The gate-to-contact space is
defined by the leakage value from the poly electrode. So we focused on the poly-to-poly space for all shrinkage.
We have been studying connected line splitting techniques. We named it ELS (end of line splitting)
technology. A critical issue is to control gaps between two narrow gate-poly's line-ends or between a narrow gatepoly's
line-end and a neighboring wire-poly line due to lower contrast in low-k1 lithography. In the case of standard
cells, especially, the patterning of narrow gate-poly projected to wire-poly is easy to shorten. To prevent this electrical
short, designers avoid keeping a narrow gap and small chip size. In order to realize a narrower gap, a splitting
technique, well-known and adopted in poly's line-ends of SRAM that are regularly arrayed, is effective. We are
investigating how to extend this technique as ELS technology for random logic of poly toward creating a 32-nm node.
In this paper, the authors focus on the following topics: 1) data preparation technique, and 2) experimental
results. Then this technology for the poly layer of random logic LSI devices is compared with result of conventional
single exposure and double pattering technology. In addition, the result that overlay control issue for ELS technology is
not severe compared with pitch doubling technology is described. ELS technology can help the designer and our
lithographer to reduce the gap and reduce the array grid size of standard cells.
Patterning of contact/via is a difficult issue for the optical lithography for each successive generation of LSIs. We examined a number of approaches to obtain a large process window and found that a dry ArF exposure tool with a large depth of focus (DOF) can form 100 nm contact holes. Our experimental results show that enough DOF can be obtained for various layouts by using sub-resolution assist feature (SRAF) technology and a unique illumination technology.