@User: Generally what you'd want is an extended drain device, which is what @User described, in which you drop silicide block over the drain area and turn it into a diffusion resistor. However, as far as I can tell, there is no silicide used in this process, or any silicide block; the diffusion resistors have the same resistance as all diffusion (and the poly resistors have the same resistance as regular poly, except for the high-valued ones). What I see on the GPIO pad layouts for the output driver, which is the array of large transistors directly under the pad, is 0.51 microns of diffusion under HVI for the drain (measuring to the edge of the contact).