#343 Need clarification on rule LU.c/LU.c1 Issue created by RTimothyEdwards I need some clarification of rule LU.c (and similarly LU.c1). According to the drawing and rule description in the IHP open PDK documentation, no part of tap diffusion creating a butted contact can be more than 6um away from the nearest diffusion contact. The drawing shows this measurement being made across the abutment boundary. I have implemented the rule in magic as it is stated. However, by doing so, the standard cell sg13gs_sdfbbp_1 causes a DRC error to be flagged on the substrate contact stripe under the ground rail. The cause is that there is a butted contact to ground in the middle of the cell. Therefore any part of the substrate contact stripe that is more than 6um from the associated diffusion contact gets marked as an error (see attached screenshot). It is obvious to me that the standard cell layout is fine; therefore, I think the rule description and illustration need to be more nuanced, but I'm not sure what the exact intent of the rule is supposed to be. I can think of two ways to make the rule work and not flag an error in situations like the standard cell flip-flop: (1) The maximum distance from any part of a tap to the nearest diffusion contact in the direction perpendicular to the butting edge must be < 6um, or (2) The maximum distance from any uncontacted part of a tap to the nearest diffusion contact must be < 6um. Which interpretation (if either) matches the actual implementation of the rule? Image Note: Looking at the klayout rules, the rule implementation contains

sizedA = Abut_NWell_Tie_Cont.ext_enlarge_inside(Act_connect.ext_interacting(Gate), 6.0.um, 0.21.um).ext_interacting(Cont_not_outside_NAct, inverted: true)

The "0.21um" measurement in the rule may be significant, as it does not appear anywhere in the rule description. I am not familiar enough with the klayout DRC rule expressions to know how to interpret

ext_enlarge_inside()

, especially with two numerical paramters. IHP-GmbH/IHP-Open-PDK