NH3 Plasma Treatment Research Articles

Improvement of thermal stability of nickel silicide film using NH3 plasma treatment

In this study, the effects of NH3 plasma pre-treatment on the characteristics of NiSi films were investigated. Nickel film was deposited on a Si(100) substrate by meal-organic chemical vapor deposition (MOCVD) using Ni(iPr-DAD)2 as a Ni precursor and NH3 gas as a reactant. Before the Ni deposition, silicon substrate was treated by NH3 plasma with various flow rates to adjust the amount of inserted hydrogen and nitrogen atoms. The Ni films showed a considerable low sheet resistance around 12 Ω/□, irrespective of the NH3 plasma pre-treatment conditions. The sheet resistance of the all Ni films was decreased after annealing at 500 °C due to formation of a low resistive NiSi phase. NiSi films with a high flow rate of NH3 plasma pre-treatment exhibited a lower sheet resistance and smoother interface between NiSi and the Si substrate than the low flow rate of the NH3 plasma pre-treated NiSi films because lots of nitrogen atoms incorporated at grain boundary of NiSi which result in reduce total surface/interface energy of NiSi and enhancement interface characteristics.

Ion-Bombarded and Plasma-Passivated Charge Storage Layer for SONOS-Type Nonvolatile Memory

This paper examined the application of ion bombardment (IB) and NH 3 plasma treatment (PT) techniques in fabricating a high-performance Si 3 N 4 charge storage layer. The IB technique can be used for creating numerous additional trap sites in the storage layer to enhance charge trapping efficiency and also causes changes in trap centroid location. In addition, the effect of centroid location on operation efficiency and reliability was investigated. Using gate-sensing and channel-sensing analysis, the changes in centroid location were demonstrated. In addition, the energy-level distribution of trap sites was clearly delineated by performing discharge-based multipulse analysis. The NH 3 PT technique can substantially passivate IB-induced shallow trap sites to increase data retention time. The influence of the NH 3 PT time on the memory characteristics of an IB-induced Si 3 N 4 sample was investigated. The optimal characteristics of an ion-bombarded and plasma-passivated Si 3 N 4 storage layer are presented. Compared with the conventional Si 3 N 4 storage layer, the optimal ion-bombarded and plasma-passivated Si 3 N 4 sample exhibited higher operation efficiency and superior reliability.

Plasma Modification of DLC Films and the Resulting Surface Biocompatibility

Diamond-like carbon (DLC) films were synthesized on a p-type silicon wafer using radio-frequency plasma composed of a mixture of Ar and C2H2 (ratio of 7 to 28). NH3 plasma treatment of as-grown DLC substrate was carried out to generate surface-terminal amino groups while oxidation of as-grown DLC was performed in O2 plasma. X-ray photoelectron spectroscopy (XPS) was used to characterize the different surface functions formed on DLC surfaces. Water contact angle measurements indicate different wetbility of modified surfaces. The cell (Mouse MC3T3-E1 pre-osteoblasts) morphology and proliferation were monitored to evaluate the biocompatibility of the modified DLC surfaces. A cell count kit-8 (CCK-8 Beyotime) was employed to determine quantitatively the viable pre-osteoblasts. The cell viability assay shows that osteoblast proliferation are improved on NH3 and O2 plasma-treated DLC surface after culturing for 1day, 2days and 3 days. The cell-surface interactions are studied by fluorescence microscopy. There are more osteoblasts as well as better spreading on the aminated and oxidized surfaces after culturing for 3 days. In summary, compared to the as-grown sample, the modified DLC shows better biocompatibility.

Surface modification of poly(ethylene-2,6-naphthalate) using NH3 plasma

We have performed NH3 plasma treatment of poly(ethylene-2,6-naphthalate) (PEN) surfaces with the purpose of incorporating nitrogen functional groups. X-Ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion spectroscopy (ToF-SIMS) were used to determine changes in the chemical structure of the PEN surfaces in response to different levels of plasma power. Plasma power had a significant impact on the type of nitrogen functional groups as well as the level of nitrogen incorporation. Considerable degradation and oxidation occurred with an excessive plasma power, rather than nitrogen incorporation. Optical emission spectroscopy (OES) confirmed that the type of chemical species present in the plasma discharge primarily determines the surface functionality with the plasma treatment. Partially decomposed ammonia species (NH and NH2) are considered to react with the PEN surface and form primarily amine groups. However, stable N2 species produced by bimolecular combination of fully decomposed atomic species led to the formation of imine groups via atomic rearrangement. Moreover, ion bombardment by N2+ species adversely affected the chemical structure of the surface, resulting in degradation of ester and carbon-carbon bonds and surface etching of carbon atoms. Open image in new window

Study on NH<sub>3</sub> Plasma-Treated Polyimide/MWNT Composites on Electrical and Surface Properties

We studied the surface modification of polyimide/multi-walled carbon nanotube (MWNT) composites resulting from plasma treatment. After NH3 plasma treatment, the surface properties of polyimide containing MWNT (U-CNT) or acid modified MWNTs (M-CNTs) were investigated using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), contact angle and electrical measurements. The surface of polyimide/MWNT composites became more hydrophilic after the NH3 plasma treatment, which improved the surface electrical conductivity of polyimide/MWNT composites. The XRD results indicate that the formation of a MWNT network structure in the polyimide matrix impeded the motion of polyimide molecules.

Effect of nitrogen passivation on the interfacial property and band offset of HfLaO/SiGe

The effect of NH3 plasma treatment on the interfacial and dielectric property between ultrathin HfLaO and strained Si0.65Ge0.35 substrate is investigated by high-resolution cross-sectional transmission electron micrographs (HR-TEM), Auger electron spectroscopy (AES), x-ray photoelectron spectroscopy (XPS), near edge x-ray absorption fine structure (NEXAFS), valence-band spectra and current density–voltage (J–V). TEM, AES and XPS results confirm that the interfacial layer with N–Hf, La–N and Si–N/Si–O–N bonds acts as a barrier layer against interdiffusions during annealing to some degree. In addition, the signals of N 1s core-level and N K-edge NEXAFS spectra are seen to disappear completely after post-deposition annealing (PDA) at 900°C due to the dissociation of unstable N chemical states during high-temperature annealing. The valence-band offsets ΔEV of HfLaO/SiGe interfaces with and without nitridation are determined to be 3.38 ± 0.01 eV and 3.20 ± 0.01 eV, respectively. While the corresponding conduction-band offsets ΔEC are found to be 1.10 ± 0.01 eV and 1.28 ± 0.05 eV, respectively. Moreover, the nitrided capacitor after PDA shows a low leakage current density (J) of ∼9.15 × 10−8 A cm−2 at a gate bias of Vg = −2.0 V.

Improved photocatalytic hydrogen production property over Ni/NiO/N–TiO2−x heterojunction nanocomposite prepared by NH3 plasma treatment

A series of visible light responsive Ni/NiO/N–TiO2−x heterojunction nanocomposites are prepared by nonthermal NH3 plasma treatment. X-ray diffraction, N2 adsorption, UV–Vis spectroscopy, Electrochemical impedance spectroscopy, Photoluminescence, and X-ray photoelectron spectroscopy are used to characterize the prepared nanocomposites. Ni species deposition decreases the surface free energy of nanocomposites, reduce the thermodynamic driving force for particle growth, thus leading to the smaller particle sizes. NH3 plasma treatment do not influence the crystal structure but shift its absorption edges to the visible light region, reduce partial NiO to metallic Ni, and form high concentration of oxygen vacancies. H2 production performances on prepared TiO2 nanocomposites are evaluated under visible light irradiation using CH3OH as scavenger. The results indicate that Ni0/Ni2+ ratio plays a significantly important role on the photocatalytic H2 production ability. Adequate oxygen vacancies concentration can improve the visible light utilization, leading to an enhanced photocatalytic performance. The prepared R–Ni(0.03)N(10)Ti exhibited the highest H2 production ability (1210 μmol h−1) and apparent quantum yield (7.5%), which is 250 times higher than that of neat TiO2. The possible mechanism is proposed.

High-Performance Gate-All-Around Poly-Si Thin-Film Transistors by Microwave Annealing With NH $_{\rm 3}$ Plasma Passivation

This paper introduces nanoscale gate-all-around (GAA) n-MOS polycrystalline silicon thin-film transistors (poly-Si TFTs) by using microwave annealing (MWA). Experimental results of MWA GAA poly-Si TFTs indicate high performances with subthreshold swing (SS) of 105 mV/dec., and ION/IOFF ratio of 107 A/A. MWA reveals sufficient dopant activation efficiency, which is equivalent to rapid thermal annealing. Additionally, the short channel effect is reduced owing to the low-temperature process of MWA and superior gate control of the GAA structure. Moreover, using NH3 plasma treatment further improves the device mobility, ION/IOFF ratio, and SS. Importantly, the proposed MWA GAA poly-Si TFT with its high performance and low-temperature process is highly promising for advanced 3-D ICs.

Detection of KRAS mutation by combination of polymerase chain reaction (PCR) and EIS sensor with new amino group functionalization

A capacitive electrolyte–insulator–semiconductor structure was introduced to quantify and distinguish point mutation from the corresponding PCR product of KRAS gene. Si3N4 surface with remote NH3 plasma is proposed to form amino group for DNA probe immobilization. The sensing response was investigated by capacitance–voltage measurement. A linear relationship was found between the reference voltage and DNA concentration from 10−6 to 10−9M. Non-complementary DNA was used for specificity testing, no DNA hybridized with DNA probes and the specificity of EIS structure with NH3 treatment was confirmed. Compared with APTES silanization and NH3 plasma treatment, the sample with NH3 plasma treatment reveal excellent selectivity and specificity, even in the presence of non-complementary DNA. The NH3 plasma treatment provided suitable method which compatible CMOS technology and could be improved accuracy of bio-sensing in clinical diagnosis.

Direct formation of amine functionality on DLC films and surface cyto-compatibility

Hydrogenated diamond-like carbon (H-DLC) films were synthesized on a p-type silicon wafer using radio frequency plasma composed of a mixture of Ar and C2H2 (ratio of 7 to 28). NH3 plasma treatment was carried out to generate surface-terminal amino groups. The treated surfaces were characterized by Raman scattering, atomic force microscopy (AFM), water contact angle, and X-ray photoelectron spectroscopy (XPS). MC3T3-E1 mouse pre-osteoblasts were cultured on the samples, and cell morphology and proliferation were investigated to evaluate the cyto-compatibility. Cell–surface interactions were investigated by fluorescence microscopy in terms of spreading and proliferation. A cell count kit-8 (CCK-8 Beyotime) was employed to determine quantitatively the viable pre-osteoblasts. The formation of the amine functionality led to better cyto-compatibility on the DLC.

Zero interface dipole induced threshold voltage shift of HfO2/SiO2 gate dielectric stacks with NH3 plasma treatment

NH3 plasma treatment on interfacial SiO2 to reduce the interface dipole effect.Energy band diagram of HfO2 films established by XPS and UV-VIS.Band-gap increase due to tetragonal phase of nitrogen doped HfO2 examined by XRD.Negligible oxygen ions movement between HfO2/nitrided SiO2 for zero dipole interface. The NH3 plasma treatment on interfacial SiO2 has been proposed to reduce the interface dipole effect of HfO2/SiO2 gate dielectric stacks. The X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible spectroscopy (UV-VIS) were used to establish the band diagram of the HfO2 films. The tetragonal crystallization phase of the HfO2 films examined by X-ray diffraction (XRD) was responsible for the band-gap increase during the NH3 plasma treatment. By using the Schottky emission and Fowler-Nordheim (F-N) tunneling, the effective electron barrier height of the Al/HfO2 gate stacks can be determined. Thus, the interface dipole and Fermi-level pinning induced flat-band voltage shifts of the Al/HfO2/SiO2/p-Si structure subjected to different NH3 plasma treatment conditions were obtained. It was found that the NH3 plasma treatment for about 4min was sufficient for achieving the zero dipole interface of the HfO2/SiO2 gate dielectric stack due to the negligible movement of the oxygen ions between the HfO2 and the nitrided oxide.

Improved electrical characteristics high-k gated MOS devices with in-situ remote plasma treatment in atomic layer deposition

Metal oxide semiconductor (MOS) devices with in situ remote plasma treatment during high-k dielectric deposition are studied in this work. The EOT value and leakage current of the MOS device with in situ NH3 plasma treated high-k dielectrics can be significantly reduced to 0.83 nm and 1.7 × 10−3 A/cm2, respectively. The stress-induced flat-band voltage shifts and leakage current are obviously reduced as well. In-situ remote plasma treatment also provides a good approach of nitridation for high-k dielectrics. The oxygen vacancy can be passivated by nitrogen, which suppresses further oxygen diffusion and the formation of the oxygen vacancies. The in situ NH3 plasma treatment is useful for high performance MOS devices with good reliability.

Low-Power and High-Reliability Gadolinium Oxide Resistive Switching Memory with Remote Ammonia Plasma Treatment

The effects of remote NH3 plasma treatment on a Pt/GdxOy/W resistive random access memory (RRAM) metal–insulator–metal (MIM) structure were investigated. We found that a decrease in the electron barrier height caused by nitrogen incorporation at the Pt–GdxOy interface can help reduce the operational set and reset voltages. Nitrogen atoms from the NH3 plasma prevent oxygen atoms in the film from diffusing through Pt grain boundaries into the atmosphere, resulting in superior retention properties (>104 s). The stability of the endurance behavior of GdxOy RRAMs was significantly improved owing to the passivation of defects in GdxOy films by nitrogen and hydrogen atoms from the remote NH3 plasma, markedly reducing plasma damage.

Enhanced Attachment of Human Osteoblasts on NH<SUB>3</SUB>-Treated Poly(L-lactic acid) Membranes for Guided Bone Regeneration

Barrier membranes for guided bone regeneration (GBR) were prepared by a solvent casting method using solutions of poly(L-lactic acid) (PLLA) and chitosan. PLLA and PLLA/chitosan membranes were treated with ammonia gas plasma. PLLA/chitosan membranes were successfully fabricated, and the surface of the PLLA/chitosan membrane was clearly modified by NH3 plasma treatment according to attenuated total reflectance (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) analyses. Additionally, water contact angle testing indicated that the hydrophilicity of these membranes was significantly increased. MG-63 cells were cultured on each type of membrane, and cell viability was examined using an MTT assay. After one week of culturing, MG-63 cells were more abundant on PLLA/chitosan membranes than on PLLA membranes. The cell viability of PLLA/chitosan membranes with plasma treatment was significantly higher than that of PLLA membranes. These results suggest that this plasma-treated membrane is suitable for GBR and is a promising source of bioactive membrane material for bone regeneration.

Effect of NH3 plasma treatment on the interfacial property between ultrathin HfO2 and strained Si0.65Ge0.35 substrate

The effect of NH3 plasma treatment on the interfacial property between ultrathin HfO2 and strained Si0.65Ge0.35 substrate has been investigated by high-resolution cross-sectional transmission electron micrographs, x-ray photoelectron spectroscopy, VBS, capacitance-voltage (C-V), and current density-voltage (J-V). TEM and XPS results confirm that interfacial layer with N–Hf and N–Si/O-N-Si bonds acts as a barrier layer against interdiffusions during annealing in some degree. The valence-band offsets ΔEV of HfO2/SiGe interfaces with and without nitridation are determined to be 3.02 ± 0.05 eV and 2.91 ± 0.05, respectively while the conduction-band offsets ΔEC are found to be 1.79 ± 0.05 and 1.90 ± 0.05 eV. The largest total dielectric constant (k) of 15.0 and smallest equivalent oxide thickness of 0.78 nm has been calculated from the accumulation capacitance of the capacitor with NH3 nitridation before post-deposition annealing (PDA). Moreover, the nitrided capacitor after PDA shows a small C-V hysteresis loop of ∼239 mV and low leakage current density (J) of ∼6.53 × 10−7 A/cm2 at a gate bias of Vg = −2.0 V.

Investigation of CH4, NH3, H2 and He plasma treatment on porous low-k films and its effects on resisting moisture absorption and ions penetration

After the H 2 , NH 3 and He plasma treatments, the leakage current density of the low-k samples are all increased. After dipping into the CMP slurry, the leakage current density increases further. While for the sample after the CH 4 plasma treatment, the leakage current density is almost the same as that of the original sample, and is still stable after dipping into the CMP slurry. Our experimental results reveal that CH 4 plasma treatment can make low- k film more resistant against the moisture uptake and keep the electrical property of the low- k films stable. This paper investigates the influence of CH 4 , NH 3 , H 2 and He plasma on properties of porous low- k film and its effects on resisting moisture absorption during CMP and ions penetration from sputtering. It is found that the H 2 , He, NH 3 plasma can cause aggressive carbon depletion in the porous low- k films and change the low- k surface from hydrophobic to hydrophilic, which will induce moisture uptake into the low- k material during the CMP process, and result in increase of the k value and leakage current density. The CH 4 plasma can make low- k material more resist against moisture uptake and keep the k value stable and a good electrical property of the low- k films.

Comparison of H2and NH3Treatments for Copper Interconnects

The surface state, electrical, and reliability characteristics of copper (Cu) interconnects after ammonia (NH3) or hydrogen (H2) plasma treatment were investigated in this study. The experimental results show that H2plasma treatment has excellent Cu oxide removal efficiency, less impact on the formation of Cu hillocks, and less damage on low-dielectric constant (low-k) dielectrics in comparison to NH3plasma treatment. However, H2plasma treatment results in a higher leakage current between the Cu lines and shorter electromigration (EM) failure time due to a weaker adhesion strength at the Cu film interface. On the other hand, NH3plasma treatment without the sufficient treatment time would lead to an increased probability of delamination at the Cu/barrier layer interface since the Cu oxide layer can not be completely removed. As a result, extending NH3plasma treatment time can efficiently reduce the adhesion failure and enlarge EM resistance as well.

Improvement of Capacitance Equivalent Thickness, Leakage Current, and Interfacial State Density Based on Crystallized High-K Dielectrics/Nitrided Buffer Layer Gate Stacks

The gate stack composed of tetragonal/cubic ZrO2 high-K dielectrics and nitrided Al2O3 buffer layer was investigated to reduce the capacitance equivalent thickness (CET), leakage current density (Jg), and interfacial state density (Dit). The high-K tetragonal/cubic phase of ZrO2 was formed by post metallization annealing at a low temperature of 450°C. The Jg was suppressed by the insertion of the Al2O3 buffer layer between ZrO2 and Si. The remote NH3 plasma nitridation on the Al2O3 buffer layer further leads to the deactivation of the oxygen vacancies and the well passivation of the Si dangling bonds. Accordingly, a suppressed Jg of 8.12 × 10−6 A/cm2 and Dit of 2.77 × 1011 cm−2 eV−1 were achieved in the crystallized ZrO2/nitrided Al2O3 gate stack with a low CET of 1.2 nm. The gate stack was also optically probed through the photoluminescence from Si, revealing that the hydrogen passivation and depassivation effects caused by the remote NH3 plasma treatment are highly correlated with the Dit. The results indicate that the crystallized high-K dielectrics/nitrided buffer layer is a promising gate stack structure to improve the electrical characteristics in the advanced metal-oxide-semiconductor devices.

Effect of hydrogen participation on the improvement in electrical characteristics of HfO2 gate dielectrics by post-deposition remote N2, N2/H2, and NH3 plasma treatments

The structural and electrical characteristics of hafnium oxide (HfO2) gate dielectrics treated by a variety of post-deposition nitridation processes, including remote N2, N2/H2 and NH3 plasma, are presented by the x-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy and electrical measurements. The XPS measurement reveals that the nitrogen content in the HfO2 thin film treated by remote nitrogen and hydrogen plasma is higher than that treated only by remote nitrogen plasma, suggesting that the hydrogen has the capability to facilitate nitrogen dissociation. An ultra-thin interfacial layer (IL) thickness (∼0.3 nm), a high dielectric constant (20), an acceptable gate leakage current density (∼9 × 10−6 A cm−2), and a low capacitance equivalent thickness (1.9 nm) of the HfO2 gate dielectric were achieved by the post-deposition remote NH3 plasma nitridation treatment. However, an IL layer as thick as 1.5 nm was observed in the sample treated only by remote N2 plasma. The results indicate that the participation of hydrogen in the nitridation process is a promising way to improve the electrical properties of HfO2 gate dielectrics.

Improvement in electrical characteristics of HfO2 gate dielectrics treated by remote NH3 plasma

We report the structural and electrical characteristics of hafnium oxide (HfO2) gate dielectrics treated by remote NH3 plasma under various radio-frequency (RF) powers at a low temperature. Significant increase of effective dielectric constant (keff), decrease of capacitance equivalent thickness (CET), reduction in leakage current density, and suppression of the interfacial layer thickness were observed with the increase of the RF power in the remote NH3 plasma treatment. The effects of hydrogen passivation and depassivation on the HfO2/Si interface due to the remote NH3 plasma treatment were also observed by the variation of photoluminescence (PL) intensity, indicating that the PL measurement is applicable to probe the interfacial properties. An ultrathin interfacial layer (∼0.3nm), a high keff, (20.9), a low leakage current density (9×10−6A/cm2), and a low CET (1.9nm) in the nitrided HfO2 film were achieved, demonstrating that the nitridation process using remote NH3 plasma under a high RF power at a low temperature is a promising way to improve in electrical properties of high-K gate dielectrics.