N2 Plasma Treatment Research Articles

Effect of N2, Ar, and O2 plasma treatments on surface properties of metals

We report the effect of N2, Ar, and O2 plasma treatments on the surface properties of metals. The carbon atoms reduced more in O2 and Ar plasma than in N2 plasma due to a chemical reaction with O2 plasma and large plasma density in Ar plasma. A water contact angle decreased after the plasma treatment regardless of the kinds of plasma gas, showing the increase in the hydrophilicity in surfaces. Synchrotron radiation photoemission spectroscopy data showed that the work function increased after N2, Ar, and O2 plasma treatments in sequence. This is due to the reduction of carbon atoms and the formation of O-rich surface in O2 plasma case.

Surface Properties of Low Density Polyethylene upon Low-Temperature Plasma Treatment with Various Gases

The surface of a LDPE was modified by Ar, O2, N2, CO2 gaseous plasma. The changes in surface morphology and surface wettability were investigated using AFM and SEM. The surface chemical changes of LDPE were also characterized by FTIR-ATR. The SEM and AFM results demonstrated variable changes in surface roughness for different types of plasma gas used, the changes being more for the Ar and N2 plasma treatments. Considering the nature of the LDPE film, XRD studies were carried out to determine changes in the percentage crystalinity. The results showed that all low pressure O2, Ar, N2, CO2 gas plasmas improved the wettability of LDPE films. Contact angles decreased significantly depending on the discharge powers and exposure times. Surface morphology was also found to vary with plasma discharge powers, exposure times, and the type of gas being used. Ar and N2 gas plasmas in general produced more superior results.

Low energy N2 ion bombardment for removal of (HfO2)x(SiON)1−x in dilute HF

The ion assisted wet removal of (HfO2)x(SiON)1−x high dielectric constant (k) materials and its effect on electrical properties were investigated. Crystallization temperature of (HfO2)x(SiON)1−x increased as the percentage of SiON increased. The crystallized (HfO2)0.6(SiON)0.4 was damaged and turned to an amorphous film via incorporation of N species into the film by N2 plasma treatment. In addition, the structure of (HfO2)0.6(SiON)0.4 was disintegrated into HfO2, SiO(N), and ON after N2 plasma treatment. N2 plasmas using low bias power were applied for wet removal of high-k films and the mechanism of the ion assisted wet removal process was explored. When high bias power was applied, the surface of source and drain regions was nitrided via the reaction between N and Si substrates. Feasibility of the low bias power assisted wet removal process was demonstrated for short channel high-k metal oxide semiconductor device fabrication by the smaller shift of threshold voltage, compared to the high bias power as...

High frequency discharge plasma induced grafting of polystyrene onto titanium dioxide powder

Grafting of polystyrene (PS) onto titanium dioxide powder was investigated. The graft polymerization reaction was induced by high frequency discharge produced N2 plasma treatment of the surfaces of titanium dioxide. IR, XPS and TGA results show that PS was grafted on the titanium dioxide powder. And the crystal structure of the titanium dioxide powder observed by XRD was unchanged after plasma treatment.

Effects of in situ N2 plasma treatment on etch of HfO2 in inductively coupled Cl2∕N2 plasmas

The etch selectivity of HfO2 to Si reported to date is poor. To improve the selectivity, one needs to either increase the etch rate of HfO2 or decrease the etch rate of Si. In this work, the authors investigate the etch selectivity of HfO2 in Cl2∕N2 plasmas. In particular, the effects of in situ N2 plasma treatment of HfO2 and Si were investigated. The silicon substrate was exposed to nitrogen plasma and was nitrided, which was confirmed by x-ray photoelectron spectroscopy. The nitrided Si etching was suppressed in Cl2∕N2 plasmas. The effectiveness of nitridation was studied with varying the plasma power, bias power, pressure, and N2 plasma exposure time. The results show that the etch resistance increased with increased power and decreased pressure. A minimum exposure time was required to obtain etch resistant property. The applied bias power increased the etch rate of Si substrate, so it should not be used during N2 plasma treatment. Fortunately, the etch rate of HfO2 was increased by the nitridation process. Therefore, HfO2∕Si selectivity can be improved by nitridation and became higher than 5 under proper exposure condition.

Surface Modification of Al2O3-Cr Ceramic by Non-isothermal N2 Plasma Treatment at Atmospheric Pressure

Al2O3/Cr composite ceramic was ion-nitrided in N2 under atmospheric pressure. The plasma was generated by two different systems: an ac high voltage corona discharge, and an ac high voltage concentric dielectric barrier discharge. An analysis of the plasma light emission revealed the presence of N ions (upto 50%) and confirmed the non-isothermal state of the plasma. The treated surface of the high melting sinter was smoothened when its components were nitrided so that Cr is transformed into Cr2N and Al2O3 is transformed into AlN.

Formation of Circuit Pattern on Liquid-Crystalline Polymer Film by Electroless Copper Plating

Liquid-crystalline polymer (LCP) films were treated with N2 plasma in order to improve adhesion with metal film. By N2 plasma treatment, hydrophilic groups such as NH, COOH and OH were introduced into LCP film and the surface of the film was roughened slightly. After N2 plasma treatment, a copper film was deposited on the LCP by electroless plating method. The circuit pattern of copper film with 0.5 mm (line) and 0.3 mm (space) intervals was fabricated on the LCP film.

Surface Modification of SiC Nanoparticles with PMMA by Low Temperature Plasma

An investigation into Poly (methyl methacrylate) (PMMA) grafted ontonano-SiC particles is reported in this study. In our experiment, thegrafting polymerization reaction is induced by radio frequency (RF)discharge of N2 plasma treatment of the nanosized powder. FTIR(Fourier transform infrared spectrum), XPS(X-ray photoelectronspectroscopy) and TGA (Thermogravimetric analysis) results revealthat PMMA is grafted onto the surface of silicon carbide powder, andthe crystal structure of the silicon carbide powder observed withXRD (X-ray diffraction) spectra is unchanged before and after theplasma graft polymerization.

Improvement of field emission from screen-printed carbon nanotubes by He∕(N2,Ar) atmospheric pressure plasma treatment

A screen-printed carbon nanotube (CNT) paste for applications to field emission emitters was treated with He, He∕Ar, and He∕N2 atmospheric pressure plasmas. The effect of the different plasma treatments on the field emission characteristics of the screen-printed CNTs was investigated. The atmospheric pressure plasma applied to the screen-printed CNT paste for 10s resulted in a reduction in the turn-on electric field. In particular, the application of a He∕N2 plasma treatment decreased the turn-on electric field from 3.13to1.29V∕μm and increased the field enhancement factor from 737 to 2775 after the treatment. These results suggest that an adequate atmospheric pressure plasma treatment of screen-printed CNTs can be effective in enhancing the field emission properties.

Enhancement of magnetic properties in (Ga,Mn)N nanowires due to N2 plasma treatment

The local structure of Mn impurities in ferromagnetic (Ga,Mn)N nanowires was investigated using extended x-ray absorption fine structure (EXAFS). By N2 plasma treatment, the nitrogen concentration increased and the ferromagnetic signal also increased. The EXAFS results showed that the Mn concentration occupying Ga sites increased and interstitially doped Mn atoms significantly decreased due to the plasma treatment. As a result, the N vacancies reduced and crystalline quality improved, resulting in the enhancement of ferromagnetic properties.

Effects of plasma treatment on microstructure and electron field emission properties of screen-printed carbon nanotube films

The effect of H2, N2 and NH3 plasma treatment on the microstructure and field emission (FE) properties of the screen-printed carbon nanotube (CNT) films has been systematically examined. Field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM) and Raman spectroscopy were used to characterize the microstructural changes of the CNTs. The results indicated that the surface of CNTs became rough, and on which a lot of nano-protuberances appeared after plasma treatment. FE experiments showed the treated CNT films had superior FE behavior with emission site density (ESD) dramatically increasing from 103 to 106/cm2. The mechanism of ESD enhancement and variation of FE properties with treatment time have been discussed.

Reduction of ohmic contact resistivity on p-GaN using N2 plasma surface treatment at room temperature

A reduction of Ni/Au ohmic contact resistivity on p-type GaN was obtained by surface treatment using N2 plasma at room temperature. For p-type GaN with a hole concentration of about 1 × 1017 cm−3, the contact resistivity decreased from 5.0 × 10−2 Ω cm2 to 3.1 × 10−4 Ω cm2 by the N2 plasma treatment, compared to that of the HCl only-treated sample. The O 1s core-level peak in the x-ray photoemission spectra shows that the N2 plasma treatment is effective in the removal of the surface oxide layer. Compared to the HCl only-treated surface, the surface Fermi level on the N2 plasma-treated surface lies about 0.58 eV closer to the valence band edge, resulting in a much smaller surface barrier height to p-GaN than the HCl only-treated surface. The smaller surface barrier height of p-GaN treated with N2 plasma can lead to a lower contact resistivity and can play an important role in lowering the metal contact resistivity to p-GaN.

Effects of O2 and N2 Plasma Treatment on 6FDA-BisAAF Fluorine-Contained Polyimide

In this work, surface modification of 6FDA-BisAAF fluorine-contained polyimide by or plasma was carried out and material characteristics of the surfaces after plasma treatment were investigated. X-ray photoelectron spectroscopy analysis reveals that plasma will react with carbon atoms in the polyimide structure to form C–O bonding on the surface and destroy the polymer structure. Reactions between nitrogen and fluorine are thermodynamically favorable during the plasma treatment and result in a significant defluorination on the surface and an increase of water absorption. The polyimides, with or without plasma treatment, were made into a metal-insulator-silicon structure to investigate its current leakage characteristics. From the current-voltage (I-V) measurement, the plasma treated sample reveals a greater leakage current than that of the untreated and plasma treated sample. The unstable bonds created by the plasma treatment may absorbed more molecules and degraded electrical characteristics. Details are discussed in the paper.

Plasma Induced Grafting of PSt onto Titanium Dioxide Powder

An investigation of grafting of polymer of styrene (PSt) onto titanium dioxide powder is reported in this paper. The graft polymerization reaction was induced by N2 plasma treatment on the surface of titanium dioxide. Infrared (IR) spectra and X-ray photospectrum (XPS) results showed that PSt was grafted onto the titanium dioxide powder. An observation by X-ray diffraction (XRD) spectra indicated that the crystal structure of the titanium dioxide powder was unchanged after the plasma treatment.

Platinum Nanoparticle Interaction with Chemically Modified Highly Oriented Pyrolytic Graphite Surfaces

Ar, N2, O2, and H2O radio frequency (13.56 MHz) plasma treatments have been carried out on insulator-supported samples of highly oriented pyrolytic graphite (HOPG). The HOPG surface was found to be...

Effects of N2, O2, and Ar plasma treatments on the removal of crystallized HfO2 film

The effects of plasma treatment using Ar, N2, and O2 on the removal of crystallized HfO2 films in a dilute HF solution were studied. The resulting damage in source and drain regions, and recess in isolation regions were also investigated. It was found that plasma nitridation with an ion energy of several hundred electron volts can lower the wet etch resistance of crystallized HfO2 films up to 70Å thick through the generation of Hf–N bonds. However, thermal nitridation did not introduce sufficient nitrogen into bulk crystallized HfO2 films to lower wet etch resistance. Plasma nitridation without bias power introduced nitrogen to the crystallized HfO2 in the region only within 10Å of the surface. The enhancement of the etch rate of crystallized HfO2 in dilute HF and the amount of recess in the active and isolation regions using N2, O2, and Ar plasma treatment have been evaluated. Results show that N2 plasma treatment is the most effective in enhancing the removal rate of crystallized HfO2 in dilute HF and minimizing recess on substrate among the plasmas studied.

Structural and electrical characterizations of ultrathin HfO2 gate dielectrics treated by nitrogen-plasma atmosphere

Ultrathin HfO2 gate dielectrics with 3.00 and 2.60nm thicknesses were prepared at 300°C by plasma-enhanced metal-organic chemical-vapor deposition. These HfO2 films were treated by N2 plasma at 300°C, and exhibit not only an excellent smooth surface morphology but also higher crystallization temperature and improved electrical properties. The N2-plasma treatment did not influence the interface charge density of the films. The 2.6nm HfO2 treated by N2 plasma showed a leakage current density of 3×10−3A∕cm2 at −1.5V, equivalent oxide thickness of 1.24nm, and flatband voltage of 2mV. We find that N2-plasma treatment in Hf-based ultrathin gate dielectrics can improve the electrical properties, as well as thermal stability.

Effect of nitrogen incorporation on improvement of leakage properties in high-k HfO2 capacitors treated by N2-plasma

The nitrogen incorporation into the HfO2 films with an EOT (equivalent oxide thickness) of 9Å was performed by N2-plasma to improve the electrical properties. The dielectric properties and a leakage current characteristics of the capacitors were investigated as a function of plasma power and plasma treatment temperature. The dielectric constant of the capacitors is not influenced by nitrogen incorporation. The N2-plasma treatment at 300°C and 70W exhibits the most effective influence on improvement of the leakage current characteristics. Leakage current density of the capacitors treated at 300°C and 70W exhibits a half order of magnitude lower than that without plasma treatment. Nitrogen incorporated into the HfO2 films possesses the intrinsic effect that drastically reduce the electron leakage current through HfO2 dielectrics by deactivating the VO (oxygen vacancy) related gap states.

EFFECT OF NITROGEN INCORPORATION ON ELECTRICAL PROPERTIES OF HIGH-K NANOMIXED HfxAlyOz FILM CAPACITORS GROWN ON RU METAL ELECTRODES BY ATOMIC LAYER DEPOSITION

ABSTRACT The HfxAlyOz nanomixed capacitors grown by atomic layer deposition were treated by N2-plasma to improve electrical properties. Especially, leakage current characteristics was studied as a function of rf power and treatment temperature. The dielectric constant of the films was not varied irrespective of an increase of rf power and treatment temperature. The leakage current densities of the films treated by N2-plasma were effectively influenced by the treatment temperature rather than rf power. The N2-plasma treatment at 300°C and 70 W exhibits the most effective influence on improvement of the leakage current characteristics. The dielectric constant, dielectric loss, and leakage current density at 2.0 V in 6 nm-thick Hf0.27Al0.24O0.49 nanomixed films treated by N2-plasma at 300°C and 70 W were approximately 16, 0.5%, and 2 × 10− 6 A/cm2, respectively.

Prevention of Cu degradation using in situ N2 plasma treatment in a dual-damascene process

The surface state of copper after an etching process using CF4 gas has been analyzed. Copper surface stability against corrosion is evaluated through a storage test performed under high-humidity conditions after the etching process. The storage test reveals that the copper surface suffered from both corrosion and oxidation. The copper degradation is caused by a postreaction between moisture and residual fluorine, wherein the resulting oxygen-containing copper film features a rough surface morphology. We examined in situ plasma treatments with several gases to reduce corrosive reactions. Results indicate that in situ N2 plasma treatment removes fluorine residue from the copper surface, and that this treatment effectively stabilizes the copper surface against corrosive conditions.