a formula of sti cmp design rule
Chemical mechanical polishing (CMP) planarization in Shallow trench isolation (STI) is a key step enabling CMOS technology scaling. STI-CMP phenomena must be carefully studied before proposing correct design rules for 'density' and dummy fill. STI-CMP planarization depends strongly on layout pattern interactions with deposited fill-oxide topography and oxide-nitride slurry selectivity. For instance, polishing characteristics of HDP fill-oxide behaves differently from TEOS fill-oxide. Traditional design-rule and dummy-fill based on "pattern density" and weighted "effective pattern density" failed to describe those phenomena adequately. To address those issues, three developments were described in this paper. First we developed deposited fill-oxide models to describe films topographies. Second, we developed a time-dependent full-die STI-CMP simulator for detail simulations. And then, we developed a formula for design rule and dummy-fill. We called this formula a "three-dimensional density rule" to differ it from traditional "pattern density rule" or "effective density rule." This "volume density rule" showed excellent correlations with the detail simulator and thus can be used in design stage effectively.
sti cmp design rules topography dfm