Layout verification in the era of process uncertainty: target process variability bands vs actual process variability bands

While there are several approaches being pursued to address runtime expectations in model based physical verification with sufficient accuracy against current manufacturing processes1, there is also the need to create models that embed a contract with the designers as to what are the realistic process control limits in a given technology for a particular layout. This is of special importance primarily when the process is still in development so that both design and process development can progress in parallel with a minimum risk of finding that the design does not yield due to poor imaging control due to sub optimal layout configurations. Several ideas are presented as to how target process variability bands can be generated and the limitations of actual process variability bands to meet such constrains. The main problem this work tries to answer is that while Optical Proximity Correction changes may be modified at a future time, the main source of uncertainty is determined by the choice of the selected resolution enhancement technique. To illustrate this point a constant layout is analyzed when applying different resolution enhancement techniques. Single exposure and double patterning results along with their corresponding process variability bands are shown for illustration. This provides an outlook as to how feasible is to provide target bands and if solutions may or may not exist in the future.