Etching of high-k dielectric Zr1−xAlxOy films in chlorine-containing plasmas

Abstract

As new, advanced high-k dielectrics are being developed to replace SiO2 in future generations of microelectronics 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, Zr1−xAlxOy (x≈0.2), in plasmas containing a mixture of Cl2 and BCl3, as a function of gas composition and ion impact energy. Higher concentrations of BCl3 enhance the etch rate as well as selectivity of Zr1−xAlxOy etching as compared to the etching of α-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 x-ray photoelectron spectroscopy was used to study the composition of the upper ∼30 Å of the film, before and at the end of the etching process. We found that the etching rate of Zr1−xAlxOy does not change with time for the range of Cl2/BCl3 ratios and ion energies investigated, whereas the α-Si etching rate in pure BCl3 plasma and at zero substrate bias decreases with time, due to the formation of a B–Si film on the surface.

Temperature-dependent Cl2/Ar plasma etching of bulk single-crystal ZnO

“…At lower temperatures we could not obtain a reliable estimate of E TH , as discussed previously. 29 Table I shows the average near-surface ͑р100 Å͒ composition of the ZnO before and after Cl 2 /Ar etching at three different temperatures. The control sample shows a signal due to adventitious carbon, as well as the lattice constituents.…”

Fabrication of ZnO photonic crystals by nanosphere lithography using inductively coupled-plasma reactive ion etching with CH4/H2/Ar plasma on the ZnO/GaN heterojunction light emitting diodes

“…This suggests that the surface reaction of ZnO with CH x radicals is favorable, and thus results in a volatile metallorganic zinc compound, such as ͑CH 3 ͒ 2 Zn as an etch product which has a very high vapor pressure of 301 Torr at 20°C. 18,[30][31][32][33][34][35][36] We have explored the etching rate of ZnO photonic crystal structure as a function of the CH 4 / ͑CH 4 / H 2 / Ar͒ flow ratio, Q, from 0.02, 0.3, and 0.7 at an ICP power of 500 W, a rf power of 200 W, 30 mTorr, a fixed argon flow rate of 5 SCCM, and total gas flow rate of 50 SCCM. One concern in using CH 4 / H 2 / Ar mixed gases for ZnO dry etching is that amorphous hydrogenated carbon ͑a-C:H͒ or CH x polymerlike layers can be easily deposited, in which the excessive deposition of a-C:H films on the surface of ZnO films can impede a continuous etching reaction.…”

Dry etching of zinc-oxide and indium-zinc-oxide in IBr and BI3 plasma chemistries

“…Refs. [44,45]). Bromine and iodine also lead to the formation of volatile oxygen reaction products such as IO 2 and BrO 2 [34].…”