The simulation, fabrication, and characterization of ultra-shallow-doped films are critical to optimizing sub-half-micron devices. This article describes key metal-oxide-semiconductor field effect transistor elements and their impact on device performance, emphasizing the need for ultra-shallow-doped films. Methods to achieve such small geometries are discussed. Future technology trends are projected. These trends are evolving at a fast pace, requiring improved simulation tools and novel measurement methods. Simulated structures are used to define device needs for abrupt composition profiles and to highlight the stringent requirements that are imposed on film characterization and model verification.