AVS 47th International Symposium
    Plasma Science and Technology Friday Sessions
       Session PS-FrM

Paper PS-FrM5
Etching of High-k Dielectric Zr@sub 1-x@Al@sub x@O Films in Chlorine-containing Plasmas

Friday, October 6, 2000, 9:40 am, Room 310

Session: Dielectrics II
Presenter: K. Pelhos, Bell Laboratories, Lucent Technologies
Authors: K. Pelhos, Bell Laboratories, Lucent Technologies
V.M. Donnelly, Bell Laboratories, Lucent Technologies
A. Kornblit, Bell Laboratories, Lucent Technologies
M.L. Green, Bell Laboratories, Lucent Technologies
R.B. Van Dover, Bell Laboratories, Lucent Technologies
L. Manchanda, Bell Laboratories, Lucent Technologies
Y. Hu, Bell Laboratories, Lucent Technologies
M.D. Morris, Bell Laboratories, Lucent Technologies
J.E. Bower, Bell Laboratories, Lucent Technologies
Correspondent: Click to Email
As new, advanced high-k dielectrics are being developed to replace SiO@sub 2@ in future generations of microelectronic devices, understanding their etch-characteristics becomes vital for integration into the manufacturing process. We report on the etch rates and possible mechanisms for one such dielectric, Zr@sub 1-x@Al@sub x@O (x > 0.2-0.35), in plasmas containing a mixture of Cl@sub 2@ and BCl@sub 3@, as a function of gas composition and ion impact energy. Higher concentrations of BCl@sub 3@ enhance the etch rate as well as selectivity of Zr@sub 1-x@Al@sub x@O etching as compared to the etching of Si, whereas increasing ion energy increases the etching rates but decreases selectivity. In a high density helical resonator plasma, etching rates on the order of 700 Å/min and 1:1 selectivity are typical. Angle-resolved XPS was used to study the composition of the upper ~30Å of the film, before, during and at the end of the etching process. The as-deposited film is found to be enriched in Al near the surface (x>0.5). During etching the surface remains slightly Al enriched (5% over the bulk concentration). The adsorbed B concentration (>50at%) in the surface region far exceeds the gas phase composition (<25at%), and the light B+ ions are driven subsurface (~5Å) during etching. Near the end of the etch process Zr and Al clear the surface at the same rate, while a thin layer of oxide (~20Å) persists. This oxide is likely formed in the deposition process rather than during etching.