American Foundries Act of 2020 This bill provides support for commercial microelectronics projects, secure microelectronics projects, and microelectronics research and development. It also requires the establishment of a national microelectronics research and development plan and implements certain safeguards. Specifically, the Department of Commerce shall award grants to certain states to assist in financing the construction, expansion, or modernization of microelectronics fabrication, assembly, test, advanced packaging, or advanced research and development facilities. Additionally, the Department of Defense (DOD) and the Director of National Intelligence may jointly enter into arrangements with private sector entities to provide incentives for the creation, expansion, or modernization of microelectronics manufacturing or advanced research and development facilities capable of producing secure and specialized microelectronics for use by DOD, the intelligence community, critical infrastructure sectors of the U.S. economy, and other national security applications. The President must establish standing subcommittees to develop a national microelectronics research and development plan and to advise the U.S. government on matters relating to microelectronics policy. Further, the Department of State, the Department of the Treasury, and Commerce shall jointly develop a plan to coordinate with foreign government partners on establishing common microelectronics export control and foreign direct investment screening measures to align with national and multilateral security priorities. Lastly, the bill prohibits firms that are owned, controlled, or influenced by the Chinese government or other foreign adversary from accessing funds appropriated by this bill.