Thickness and polarity dependence of intrinsic breakdown of ultra-thin reoxidized-nitride for DRAM technology applications

Abstract

This paper discusses the charge-trapping and intrinsic breakdown characteristics of ultra-thin reoxidized nitride with deeptrench capacitor structures for a range of thickness, voltages, and temperatures. Strong polarity dependence of charge-trapping and time-dependent dielectric breakdown (TDDB) is reported. For the first time, a physical model is proposed to relate the asymmetric charge injection and trapping to this intrinsic breakdown characteristic in thin reoxidized nitride. The thickness dependence of TDDB is also investigated and used for a reliability projection of the oxide equivalent thickness down to 2.9 nm.

Charge transport in thin interpoly nitride/oxide stacked films

“…Transport models, invoking a dominant electron conduction for both gate polarities, 14,16 have been proposed, as well as hole flow models for nitride conduction ͑where the anodic oxide reduced hole tunneling from the poly-silicon to the nitride͒. 6,9,11,25,26 A quantitative current conduction model, based on electron ͑hole͒ Fowler-Nordheim current through the cathodic ͑anodic͒ SiO 2 and hole Poole-Frenkel current in the Si 3 N 4 is proposed in Refs. 6 and 10.…”

TDDB evaluations and modeling of very high-voltage (10kV) capacitors

“…f* is the fraction of charge transferred from the Si-ion to the O-ion ( f* = 0.6 using the Pauling electronegativity equation) , η(m,n) is a bonding parameter depending only on the bonding exponents and is given by (5) , and k = 3.9 is the dielectric constant for silica. Thus, for Si-O bonding described by the Born-Landé (9,1) potential, the predicted effective dipole moment for TDDB is ρ eff = 13.3 eA.…”

Oxide-Nitride Storage Dielectric Formation in a Single-Furnace Process for Trench DRAM

“…The purpose of the elaborately adjusted thickness of the oxide and nitride for the ON dielectric was to have nearly identical thickness with those of the N2ONO dielectric, to study the impact of the oxide and nitride growth sequences on the electrical characteristics. To render the electron tunneling from the oxide side that causes a worse reliability performance [10], different voltage polarity was applied to each dielectric for electrical characterization.…”