Open PDKs (Process Design Kits): SKY130, GF180, IHP SG13G2
The idea
Until 2020, every manufacturable PDK (Process Design Kit) was under NDA (Non-Disclosure Agreement), which meant no open tool could be tested end to end on a real process and no student could tape out without a university agreement. Three kits changed that:
- SKY130 (SkyWater, with Google; released 2020): a 130 nm CMOS (Complementary Metal-Oxide-Semiconductor) (Complementary Metal-Oxide-Semiconductor) process with 5 metal layers plus local interconnect, several standard-cell libraries, and public DRC (Design Rule Check) and LVS (Layout Versus Schematic) decks. Manufactured through Efabless shuttles. The most used open kit and the one the OpenROAD flow targets first.
- GF180MCU (GlobalFoundries, with Google; released 2022): a 180 nm process aimed at microcontrollers, higher voltage options, also on shuttle programs.
- IHP SG13G2 (IHP (Innovations for High Performance Microelectronics), Germany; released 2023): a 130 nm SiGe (Silicon-Germanium) BiCMOS (Bipolar CMOS (Complementary Metal-Oxide-Semiconductor)) process with high-speed bipolar devices, open with active development and multi-project wafer runs; notable for its open assembly-level data.
All three publish the full file set described on the PDK (Process Design Kit) anatomy page, under Apache-2.0 style licenses.
What they are and are not
They are real, mature, manufacturable processes: chips designed on them work. They are not advanced nodes: single-patterned, planar transistors, few metal layers, and rule decks small enough to read. That is exactly what makes them teachable, and it is why the graded problems on this platform run on SKY130 with the OpenROAD flow: every metric a problem grades is produced by real tools on a real kit.
Pros, cons, and the trade-off
Strengths
- Real silicon: shuttle programs turn a passing layout into a packaged chip.
- Complete and inspectable: every file kind, readable rules, public libraries.
- Tool development: open EDA (Electronic Design Automation) tools can finally be validated end to end.
Weaknesses
- Old nodes: 130 to 180 nm, so advanced-node effects (multi-patterning, FinFET libraries, deep metal stacks) are absent.
- Smaller libraries and fewer corners than commercial kits.
- Kit maturity varies: documentation gaps and deck bugs are fixed by the community rather than a foundry support desk.
The trade-off
Open PDKs (Process Design Kits) trade node advancement for openness, and for teaching and tool development that is the right trade: everything on this site that runs a real tool runs it against one of these kits, and everything it grades is therefore real.
Where to start
- The SKY130 documentation for the process; the OpenROAD flow's sky130hd platform for the flow's view of it.
- Efabless for shuttle schedules on SKY130 and GF180MCU.
- The IHP open PDK (Process Design Kit) repository for SG13G2.