The SKY130HD enablement available in the OpenROAD-flow-scripts GitHub repo is a five-metal stack enablement. However, memory macros have blockages till metal four, so a five-metal stack is not enough to route our macro dominant testcases. So we extended SKY130HD to a nine-metal fake layer stack in the OpenROAD-flow-scripts GitHub repo.
In this enablement, each of the five routing layers and four cut layers have different lef properties (.e.g, minimum spacing, width, enclosure, etc.). Consider the five layers of the metal stack are Ma, Mb, Mc, Md and Me, and the stack configuration is named as 1Ma_1Mb_1Mc_1Md_1Me. We replicate the first four metal layers to generate the nine-metal layer FakeStack where the configuration is 2Ma_2Mb_2Mc_2Md_1Me. We use this nine-metal layer FakeStack of SKY130HD as one of the enablements. The getTechLef.tcl can be used to generate a FakeStack of layer configuration x1Ma_x2Mb_x3Mc_x4Md_1Me, where xi is greater or equal to one.
We use the bsg_fakeram memory generator available in the bsg_fakeram GitHub repo to generate the required SRAMs. The sky130hd.cfg is the configuration file used to generate all the required memories.
With this combined enablement, testcases with SRAMs can be synthesized, placed and routed using both proprietary (commercial) tools such as Cadence Genus/Innovus, and open-source tools such as OpenROAD.
The ./lef directory contains the technology, standard cell and macro lef files, the ./lib directory contains the standard cell and macro liberty files.