ENHANCED GROWTH OF DEVICE-QUALITY COPPER BY HYDROGEN PLASMA-ASSISTED CHEMICAL VAPOR-DEPOSITION

A hydrogen plasma-assisted chemical vapor deposition (PACVD) process has been developed for the growth of device-quality copper films on large-area substrates. The process takes advantage of the high concentration of reactive hydrogen species present in the low-power plasma to enhance the clean reduction of copper beta-diketonate precursors such as bis(hexafluoroacetylacetonato)copper(II). Copper films were produced at substrate temperatures of 160-170-degrees-C, reactor working pressures of 1.3-1.7 Torr, hydrogen flow rates between 700 and 1200 cc/min, and hydrogen plasma power ranging from 15 to 30 W (with an equivalent power density of approximately 0.10-0.25 W/cm2. The films were characterized by x-ray photoelectron spectroscopy, Rutherford backscattering spectroscopy, scanning electron microscopy (SEM), and cross-section SEM. These studies indicate that PACVD processes pure, dense, highly uniform films, and allows conformal step coverage and complete hole filling of patterned test structures. Growth rates over large-area substrates were as high as 1000 angstrom/min.