Charge Trapping and Decay Mechanism in Post Deposition Annealed Er₂O₃ MOS Capacitors by Nanoscopic and Macroscopic Characterization

Abstract

In this paper, the charge trapping and decay mechanism is investigated in post deposition rapid thermal anneal (RTA) and furnace anneal (FA) erbium oxide (Er 2 O 3 ) ultrathin films by Kelvin probe force microscopy (KPFM) technology. The trap density is calculated by the contact potential difference measurements obtained from KPFM. Furthermore, it is compared with the trap density calculated from the electrical measurements for Er 2 O 3 MOS capacitors to give an insight on the reliability of KPFM for trap density estimation. Experimental results showed that post deposition RTA treatment results in higher trapping as compared to FA treatment on Er 2 O 3 ultrathin films. It was observed that vertical charge leakage plays a dominant role in Er 2 O 3 as compared to lateral charge spreading. The space-charge-limited conduction mechanism was observed in Er 2 O 3 MOS capacitors, which was used to study the charge injection and decay mechanism. This investigation may help to fill the trap density computation gaps between nanoscopic KPFM and macroscopic capacitance-voltage-based electrical measurements for nanoscale MOS-based applications.Index Terms-Charge trapping, high-κ, rare earth oxides (Er 2 O 3 ), rapid thermal annealing (RTA), Kelvin probe force microscopy (KPFM), MOS.

Charge Trapping Control in MOS Capacitors

“…Figure 11 shows the result of a second experiment performed in another pristine device. In this second case initially 3.20x10 12 3.01x10 12 3.34x10 12 3.50x10 12 Figure 8. Comparison between experimental C-V curves (ticks) and simulation results of the reference device (dashed lines).…”

Integration of High‐Performance Cost‐Effective Copper‐Metal‐Organic‐Nanocluster‐based Gate Dielectric for Next‐Generation CMOS Applications

“…Also, dominant loss due to shallow/interface traps rather than deep‐level/bulk traps indicates the formation of smooth large‐area Cu‐MOCs thin films with minimal uniformities aligning suitably with discussion in Section 2.1. At high frequencies, both capacitance and conductance measurements are affected by series resistance; [ 58 ] hence series resistance corrected (blue curve) and noncorrected (red curve) normalized G–V characteristics are shown in (Figure S6, Supporting Information) for Al/Cu‐MOCs/Si structures. The series resistance corrected conductance G C is extracted from C–V characteristics given by relation (equation S3, Supporting Information).…”

Injection and Retention Characterization of Trapped Charges in Electret Films by Electrostatic Force Microscopy and Kelvin Probe Force Microscopy

“…[ 16,54,55,57,106 ] Liu and coworkers explored the effect of the HfO 2 thickness, postdeposition annealing temperature, and charge retention temperature on the vertical and lateral charge dissipation by KPFM. [ 16,54,106 ] In addition, the trapped charge properties of a ferroelectric film, [ 56 ] a fluorocarbon layer, [ 87 ] sapphire surfaces, [ 107 ] a double barrier CeO 2 /Si/CeO 2 /Si structure, [ 90 ] and undoped and copper‐doped zinc oxide (ZnO:Cu) films [ 108 ] have also been investigated by EFM/KPFM. Wong et al detected the surface potential of trapped charges for undoped and copper‐doped zinc oxide films using KPFM.…”

“…The decay mechanisms have been reported, such as neutralizing the part‐trapped charges of an electret by attraction of the environmental charges, [ 2,47,78,104 ] the water dipoles and adsorbed water, [ 46,47 ] bulk space charge motion, [ 122 ] self‐repulsion, [ 47,122 ] Coulombic interaction, [ 52 ] and thermal diffusion. [ 47 ] Some researchers reported that the vertical charge leakage acted as a dominant role of charge loss with respect to lateral charge redistribution for HfO 2 , [ 106 ] Er 2 O 3 , [ 54 ] and Al 2 O 3 films, [ 55 ] while the cancellation of lateral surface conduction enhanced the charge retention ability. [ 46,123 ] The nanocrystal density will affect the retention properties of trapped charges when the nanocrystals are embedded in a silicon matrix.…”

“…In the past decade, EFM/KPFM has been successfully used to study the injection and retention of trapped charges in inorganic films, [ 16,25,45,46,52–57 ] polymer electrets, [ 47,58–60 ] organic small molecules, [ 42,44 ] the composition of polymer and organic semiconductors, [ 27,41,43 ] nanostructure, [ 48–51,61–78 ] double‐barrier CeO 2 /Si/CeO 2 /Si structures, [ 79 ] DNA molecules, [ 39–80 ] and thin‐film transistors. [ 81–86 ] For example, Heim et al proved that EFM is a useful technique to study the electronic properties of an organic monolayer island at the nanometer scale and found that both carriers are delocalized over the whole island in crystalline monolayer islands, while carriers stay localized at their injection point on a disordered monolayer.…”