Control of SiO 2 /Si interface defects generation during thin dielectric film etching using CH x F y /Ar/O 2 plasma

To investigate the electrical properties and degradation features of dielectric materials during plasma exposure, we developed an in-situ impedance spectroscopy (IS) system. We applied the proposed system to monitor SiO2/Si structures exposed to Ar plasma. By analyzing the measured data based on an equivalent circuit model considering the plasma and SiO2/Si structures, we obtained the resistance (R) and capacitance (C) values for the SiO2 film and SiO2/Si interface. In a cyclic experiment of in-situ IS and high-energy ion irradiation, we characterized dielectric degradation by ion irradiation based on the variations in the R and C values of the SiO2 film. A continuous in-situ IS measurement revealed temporal variations in the electrical properties of the film and interface independently. The thickness-dependent degradation observed for the RC variation was analyzed and compared with the results of previous ex-situ measurement studies. This study demonstrates that the in-situ IS measurement technique is promising for monitoring plasma-assisted dry processes.

Section: Temporal Change In Sio 2 /Si Properties Monitored Using In S...mentioning

confidence: 99%

In situ electrical monitoring of SiO₂/Si structures in low-temperature plasma using impedance spectroscopy

Morozumi

Goya

Kuyama

et al. 2023

“…As many studies have shown that hydrogen affects the CF layer thickness and etching yield, 3,6,19,26,[30][31][32][33] the hydrogen atoms in the incident ions tend to form HF and scavenge fluorine atoms from the CF layer. In addition, the CF layer is easily consumed during the etching of the underlying material through the formation of HCN.…”

Section: Surface Reactionsmentioning

confidence: 99%

Phenomenological model for predicting C _x H _y F _z ⁺ ion etching yields of SiO₂ and SiN _x substrates

Kawamoto¹,

Kataoka²,

Kuboi³

et al. 2023

In this study, a novel phenomenological model is developed to predict the etching yields of SiO2 and SiNx substrates by fluorocarbon (FC) and hydrofluorocarbon (HFC) ions. The CF layer thickness and reactive layer chemistry are described, which significantly affect the etching yields. The study focuses on the dependence of the atomic component of the ion and the incident ion energy of the ion on the etching yield. Some assumptions enable the calculation of ion etching yields in a short turn-around-time. The proposed model can predict the etching yields of other larger species at the higher incident ion energy. The obtained simulation results are in good agreement with the experimental data. The optimal etching ions for high aspect ratio etching are comprehensively investigated using the proposed model, providing a better understanding of the differences in the underlying material and the atomic component of the ion.

“…In this section, we have discussed the physical damage caused by ions, but high-energy incident light such as UV and vacuum UV light generated from plasma can also cause the material itself to deteriorate and lead to defect formation at the interface. [35][36][37][38][39][40] In the future, it will be necessary to reduce the damage caused by quantitatively analyzing the transmission and absorption of this plasma light, which varies according to the wavelength of the light generated from the plasma, the composition of the materials used, and the film thickness.…”

Section: Suppression Of Damagementioning

confidence: 99%

Quantitative control of plasma and surface reactions for dielectric film etching

Tatsumi¹

2022

Self Cite

This paper reviews reaction control in the dry etching of insulating films. High ion fluxes are required for high-speed SiO2 processing. However, because atomic F generation due to excessive fluorocarbon gas dissociation causes reduced selectivity, the number of electron collisions should be reduced by using short residence times. The C–F-based polymer thickness formed during processing varies based on the oxygen content of the material to be etched. To achieve high etch selectivity, the incident flux balance must be adjusted quantitatively to ensure that the polymer becomes thinner during etching and thicker as the underlying material is exposed. Even under high selectivity conditions, incident ions cause damage at the moment the underlying material is exposed. To suppress this damage, the ion penetration depth, which depends on both ion energy distribution and ion composition, must be reduced. Recently, atomic layer etching combined with C–F polymer deposition and removal using Ar ion irradiation has been studied. To improve the accuracy of such cyclic etching processes, it is important to understand and control the transient states of both plasma and surface reactions quantitatively.