Unit Processes

A complete Si-based CMOS integrated circuit process flow usually includes hundreds to thousands of basic steps. These basic process steps are referred to as “unit process” steps as they can be executed at a single tool (e.g., furnace, chamber, equipment, lithography scanner, etc.). In manufacturing, several basic unit process steps can be grouped as a “module process” loop for a well-defined function (e.g., STI module, gate stack, lithography align/exposure/develop/implant/PR-removal, contact formation, metal/via formation by dual-damascene, etc.). Similarly, these modules can be further grouped into frontend-of-line (FEOL), middle-of-line (MOL), and back-end-of-line (BEOL), to form a complete CMOS integration process flow.