Abstract
This work aimed to study on the effects of plasma treatment on flat band voltage (Vfb) and equivalent oxide thickness (EOT) using Metal-organic Chemical Vapor Deposition (MOCVD) TiN film as p-MOSFETs metal gate electrode. Theplasma treatment conditions effect on the resistance and composition properties of MOCVD TiN, consequently, they can modulate work function and control threshold voltage. The effects of “plasma treatment” were imposed to favor the formation of Ti-N bonds, thus decreasing the rate Ti-C bond and favoring a crystallized stoichiometric TiN phase to increase PMOS Vfb shift. Meanwhile, plasma treatments accelerate interfacial oxide formation and increase EOT. On the other hand, EOT increases with the increase of plasma treatment time and power in this work, but Vfb does not always increase and reach a max value.
Highlights
Scaling of sub-45 nm complementary metal-oxide semiconductor CMOS devices requires metal gate electrodes to address restricting factors of usual poly silicon gates, such as poly depletion, doping species penetration, and Fermi level pinning [1,2]
It can be seen that the diffraction intensity is very weak without plasma treatment condition, and extending plasma treatment time makes Metal-organic Chemical Vapor Deposition (MOCVD) Titanium nitride (TiN) film (200) preferential orientation more remarkable and the full width half maximum (FWHM) of (002) diffraction more narrow, it is known that the Full Width Half Maximum (FWHM) obtained from the result of X-Ray Diffraction (XRD) relates to finite crystallite sizes, stacking faults, micro twins, stresses, dislocations, concentration variations, which parameters have a strong dependence on the crystal quality of films [10]
The chemical composition of MOCVD TiN film was analyzed by X-Ray Photoelectron Spectrometer (XPS), the Ti2p peak can be fitted by eight Gaussian functions as Figure 4 shown, the XPS spectrum of Ti2p shows obviously different with and without plasma treatment
Summary
Integration of the high K dielectric/metal gate stack into a metal-oxide-semiconductor (MOS) transistor provides some new challenges, such as Vfb and EOT control [3,4]. The requirements for the metal gates are as follows: favorable work functions, low sheet resistance, thermal stability, and compatibility with high-k dielectric Among all the potential candidates for metal gate electrodes, TiN gates showed promising results such as thermal stability with the high-k gate dielectrics and process compatibility [5,6]. N2 and H2 plasma treatment after TiN thin film growth modifies film composition and physical properties. Capacitors with W/TiN gate stacks are fabricated for Vfb and EOT extraction, effects of TiN growth time, plasma treatment time and power on the work function and EOT are systematically investigated
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