Developments of Plasma Etching Technology for Fabricating Semiconductor Devices

Plasma etching technologies such as reactive ion etching (RIE), isotropic etching, and ashing/plasma cleaning are the currently used booster technologies for manufacturing all silicon devices based on the scaling law. The needs-driven conversion from the wet etching process to the plasma/dry etching process is reviewed. The progress made in plasma etching technologies is described from the viewpoint of requirements for the manufacturing of devices. The critical applications of RIE, isotropic etching, and plasma ashing/cleaning to form precisely controlled profiles of high-aspect-ratio contacts (HARC), gate stacks, and shallow trench isolation (STI) in the front end of line (FEOL), and also to form precise via holes and trenches used in reliable Cu/low- k (low-dielectric-constant material) interconnects in the back end of line (BEOL) are described in detail. Some critical issues inherent to RIE processing, such as the RIE-lag effect, the notch phenomenon, and plasma-induced damage including charge-up damage are described. The basic reaction mechanisms of RIE and isotropic etching are discussed. Also, a procedure for designing the etching process, which is strongly dependent on the plasma reactor configuration, is proposed. For the more precise critical dimension (CD) control of the gate pattern for leading-edge devices, the advanced process control (APC) system is shown to be effective.