Plasma Chemical Vapor Deposition Process Research Articles

Tribological behavior of diamond particles reinforced hafnium matrix composite coatings on Ti6Al4V

The diamond particles reinforced hafnium matrix composite coatings are prepared by the double glow plasma surface alloying technique combined with the microwave plasma chemical vapor deposition process (MPCVD). The effect of the Hf diffusion layers and diamond particles on their phase transformation, microstructure evolution, and wear behavior is systematically investigated. The results reveal that the surface of the Hf-alloying coating which is fabricated by plasma surface metallurgy emerged discrete micropores due to the Kirkendall effect during the plasma reverse sputtering. With the reverse sputtering time increasing, the general pore size increases, and the deposition layer has been completely sputtered out, leaving the Hf diffusion layer with a thickness of about 10 μm. After diamond particles deposition by MPCVD, the diamond particle reinforced hafnium matrix composite coatings with carbide and diamond coexisting were formed. The wear experiments were conducted in ambient air with a reciprocating friction tester, demonstrating that the diamond particle reinforced hafnium matrix composite coatings exhibited good antifriction performance with the decrease of wear rate by ∼8 times due to the lubrication effect of the diamond and graphite particles.

Directly tuning the surface morphologies and electron pathway of graphite/diamond composite films for enhanced electron field emission

Cathode electron field emitters are widely used in high-power and high-frequency vacuum electron devices. The development of novel technique to fabricate the emitters with high electron field emission performance has stimulated extensive research. Here we present a unique one-step microwave plasma chemical vapor deposition process to fabricate the graphite/diamond composite films. The gaseous methane is replaced by liquid n-butylamine, which acts as the single reactive carbon source. The components and surface morphologies of the graphite/diamond composite films can be effectively tuned upon changing the deposition temperatures. The vertically oriented graphite/diamond composite film with a graphite-diamond-graphite nanostructure is obtained and shows superior electron field emission performance of low turn-on field (E0 = 4.0 V/µm) and high emission current density (J@8.8 V/µm = 13.0 mA/cm2). Our study reveal that the sharp edges, appropriate distribution density of the nanosheets, as well as good electron pathway from the bulk to the surface are the key ingredients for the electron field emission performance. This work on graphite/diamond composite films provides a new carbon source instead of methane to fabricate the emitters with high electron field emission performance, which may promote the industrial-scale application.

Synthesis of Graphene and Related Materials by Microwave-Excited Surface Wave Plasma CVD Methods

Several kinds of chemical vapor deposition (CVD) methods have been extensively used in the semiconductor industries for bulk crystal growth, thin film deposition, and nanomaterials synthesis. In this article, we focus on the microwave-excited surface wave plasma CVD (MW-SWP CVD) method for growth of graphene and related materials. The MW-SWP CVD system consisting of waveguide, slot antenna, and dielectric windows is significant for generating high density plasma with low electron temperature, enabling low temperature growth of materials without damaging the surface of base substrates. The synthesis of graphene and hexagonal boron nitride (hBN) films has been achieved on metals, semiconductors, insulators, and dielectric substrates for application in photovoltaics, sensors, batteries, supercapacitors, fuel cells, and various other electronic devices. The details of the synthesis process for graphene films, vertically-oriented graphene, doped-graphene, and hBN films by the MW-SWP CVD method are summarized to understand the growth mechanism, which will enable further development of the plasma CVD process for material synthesis at a low temperature for industrial applications.

Soliton frequency comb generation in CMOS-compatible silicon nitride microresonators

The monolithic integration of soliton microcomb devices with active photonic components and high-frequency electronics is highly desirable for practical applications. Among many materials, silicon nitride ( SiN x ) waveguide layers prepared by low-pressure chemical vapor deposition (LPCVD) have been the main platform for on-chip optical frequency comb generation. However, the high temperatures involved in LPCVD render it incompatible as a back-end process with complementary metal oxide semiconductor (CMOS) or active III-V compound semiconductor fabrication flows. We report the generation of coherent soliton frequency combs in micro-ring resonators fabricated in deuterated silicon nitride ( SiN x : D ) waveguides with a loss of 0.09 dB/cm. Deposited at 270°C by an inductance-coupled plasma chemical vapor deposition (ICP-CVD) process, the material preparation and fabrication flow are fully CMOS-compatible. These results enable the integration of silicon-nitride-based optical combs and photonic integrated circuits (PICs) on prefabricated CMOS and/or III-V substrates, therefore marking a major step forward in SiN x photonic technologies.

Site‐selective atmospheric pressure plasma‐enhanced chemical vapor deposition process for micrometric deposition of plasma‐polymerized methyl methacrylate

AbstractAn atmospheric pressure plasma chemical vapor deposition process designed for the site‐selective deposition of organic functional materials with a sub‐millimetric lateral resolution is presented in this study. Injecting methyl methacrylate vapor in plasma post‐discharge allowed to synthesize plasma‐polymerized methyl methacrylate (ppMMA) coatings on metallic, dielectric, and polymer substrates at close to room temperature (40°C). A circular dot, as small as 400 µm in diameter, of ppMMA is deposited and characterized by Fourier‐transform infrared spectroscopy, X‐ray photoelectron spectroscopy, and high‐resolution mass spectrometry. Oligomeric species of poly‐MMA up to n = 18 have been detected, evidencing the particularly “soft” polymerization offered by the presented process.

Gas dependent growth study of hexagonal boron nitride synthesized by microwave assisted surface wave plasma chemical vapor deposition process

Gas dependent growth study of hexagonal boron nitride synthesized by microwave assisted surface wave plasma chemical vapor deposition process

Effect of magnetic field on the synthesis of carbon nanotubes using MPECVD

CNT production is limited by issues regarding CNT growth and morphology. Due to this, further studies on experimental factors regarding CNT production are needed to optimize CNT production in a commercial scale. This study focuses mainly on the determination of the effects of the presence of a magnetic field during CNT synthesis in a Microwave Enhanced Plasma Chemical Vapor Deposition (MPECVD) process using a Whirlpool AVM585 conventional microwave oven. The study also determined the effects of hydrogen catalyst plasma pretreatment on CNT growth. The experiment was based on a Taguchi orthogonal array design. The effects of the experimental factors such as magnetic field strength (0, 5, and 10 mT), catalyst pretreatment time (10, 15, and 20 min), hydrogen gas flow rate (25, 50, and 75 mL/min), and microwave power (451, 570, and 740 W) on the responses such as the catalyst nanoparticle Feret diameter, CNT diameter, tortuosity, weight, and purity were investigated. Among the design factors, application of magnetic field at 10 mT improved all the responses, most notably the CNT diameter and tortuosity being reduced by 60% and 48% compared to runs with no magnetic field, respectively. Under tortuosity, magnetic field was the design factor which had the greatest effect on decreasing the tortuosity of the CNTs at around 100 times the effect measured under other design factors. Catalyst plasma pretreatment was most optimal at the highest hydrogen flow rate and microwave power setting, under the influence of the highest magnetic field strength. The effects of the factors during catalyst plasma pretreatment also resulted to improved characteristics of the CNTs during the CNT synthesis. Overall, the findings suggest that the application of a magnetic field during catalyst plasma pretreatment and the subsequent CNT synthesis results to catalyst nanoparticles and CNTs with improved properties such as lower catalyst nanoparticle Feret diameter, CNT diameter, tortuosity and higher CNT yield and purity.

Carbon nano-flake ball with a sandwich-structure composite of diamond core covered by graphite using single-step microwave plasma chemical vapor deposition

A three-dimensional nanostructure of carbon material similar to a desert rose stone, named the carbon nano-flake ball, was fabricated by a single-step microwave plasma chemical vapor deposition process. Silicon substrate pretreated with different methods was used to grow carbon nano-flake balls and to control their coverage ratio. The dimension of single carbon nano-flake ball was found to be within 10 μm and it was constructed from multiple nano-scale-thickness flakes at angles. In turn, the nano-scale-thickness flakes were composed of a sandwich-structured composite, which contained a diamond core covered by graphite. The width and length of separate flakes can exceed 1 μm. The measurement of field emission properties revealed that the turn-on electric field can be as low as 2.13 V/μm, which is better than a conventional diamond film. In addition, the growth mechanism of carbon nano-flake balls was proposed. The carbon species (CH, C2) formed a diamond cluster at the defects on the surface of silicon substrate or spots where Fe-based catalyst located. It was discovered that the deposition temperature and CN specie are the key factors to grow carbon nano-flake ball.

3D superelastic graphene aerogel-nanosheet hybrid hierarchical nanostructures as high-performance supercapacitor electrodes

A three-dimensional graphene-based nanostructure with graphene aerogel templating graphene nanosheets (GA-GNs) has been fabricated via a modified hydrothermal method, followed by a microwave plasma chemical vapor deposition process. The mechanical properties of such hybrid nanostructures, for the first time, were quantitatively measured to demonstrate their superior mechanical robustness with stress and Young's modulus up to 96 kPa and 181.25 kPa, respectively. Finite-element modeling further reveals the mechanical strengthening mechanism with GNs as stiffening ribs layered over thin cellular walls within the GA. Moreover, GA-GNs present excellent electrical conductivity as high as ∼1000 S/m, showing great promise as high-performance supercapacitor electrodes. The as-prepared free-standing and binder-free GA-GN electrode exhibits a high specific capacitance of 245 F g−1 (based on the entire electrode mass) which corresponds to a high areal capacitance of 1.1 F cm−2, desirable rate capability and outstanding cyclic stability with a capacitance retention of 92% over 10000 cycles. To assess their practical functionality, a two-terminal symmetric all-solid-state supercapacitor based on such all-carbon electrodes was fabricated. Such supercapacitor devices exhibited desirable areal capacitance, low internal resistance and outstanding cyclic stability.

Morphological Transition in Diamond Thin-Films Induced by Boron in a Microwave Plasma Deposition Process.

The purpose of this study is to understand the basic mechanisms responsible for the synthesis of nanostructured diamond films in a microwave plasma chemical vapor deposition (MPCVD) process and to identify plasma chemistry suitable for controlling the morphology and electrical properties of deposited films. The nanostructured diamond films were synthesized by MPCVD on Ti-6Al-4V alloy substrates using H2/CH4/N2 precursor gases and the plasma chemistry was monitored by the optical emission spectroscopy (OES). The synthesized thin-films were characterized by x-ray diffraction and scanning electron microscopy. The addition of B2H6 to the feedgas during MPCVD of diamond thin-films changes the crystal grain size from nanometer to micron scale. Nanostructured diamond films grown with H2/CH4/N2 gases demonstrate a broad (111) Bragg x-ray diffraction peak (Full-Width at Half-Maximum (FWHM) = 0.93° 2θ), indicating a small grain size, whereas scans show a definite sharpening of the diamond (111) peak (FWHM = 0.30° 2θ) with the addition of boron. OES showed a decrease in CN (carbon–nitrogen) radical in the plasma with B2H6 addition to the gas mixture. Our study indicates that CN radical plays a critical role in the synthesis of nanostructured diamond films and suppression of CN radical by boron-addition in the plasma causes a morphological transition to microcrystalline diamond.

Control of nanoparticle size and amount by using the mesh grid and applying DC-bias to the substrate in silane ICP-CVD process

The effect of applying a bias to the substrate on the size and amount of charged crystalline silicon nanoparticles deposited on the substrate was investigated in the inductively coupled plasma chemical vapor deposition process. By inserting the grounded grid with meshes above the substrate, the region just above the substrate was separated from the plasma. Thereby, crystalline Si nanoparticles formed by the gas-phase reaction in the plasma could be deposited directly on the substrate, successfully avoiding the formation of a film. Moreover, the size and the amount of deposited nanoparticles could be changed by applying direct current bias to the substrate. When the grid of 1 × 1-mm-sized mesh was used, the nanoparticle flux was increased as the negative substrate bias increased from 0 to – 50 V. On the other hand, when a positive bias was applied to the substrate, Si nanoparticles were not deposited at all. Regardless of substrate bias voltages, the most frequently observed nanoparticles synthesized with the grid of 1 × 1-mm-sized mesh had the size range of 10–12 nm in common. When the square mesh grid of 2-mm size was used, as the substrate bias was increased from – 50 to 50 V, the size of the nanoparticles observed most frequently increased from the range of 8–10 to 40–45 nm but the amount that was deposited on the substrate decreased.

The effect of substrate holder size on the electric field and discharge plasma on diamond-film formation at high deposition rates during MPCVD

The effect of the substrate holder feature dimensions on plasma density (ne), power density (Qmw) and gas temperature (T) of a discharge marginal plasma (a plasma caused by marginal discharge) and homogeneous plasma were investigated for the microwave plasma chemical vapor deposition process. Our simulations show that decreasing the dimensions of the substrate holder in a radical direction and increasing its dimension in the direction of the axis helps to produce marginally inhomogeneous plasma. When the marginal discharge appears, the maximum plasma density and power density appear at the edge of the substrate. The gas temperature increases until a marginally inhomogeneous plasma develops. The marginally inhomogeneous plasma can be avoided using a movable substrate holder that can tune the plasma density, power density and gas temperature. It can also ensure that the power density and electron density are as high as possible with uniform distribution of plasma. Moreover, both inhomogeneous and homogeneous diamond films were prepared using a new substrate holder with a diameter of 30 mm. The observation of inhomogeneous diamond films indicates that the marginal discharge can limit the deposition rate in the central part of the diamond film. The successfully produced homogeneous diamond films show that by using a substrate holder it is possible to deposit diamond film at 7.2 μm h–1 at 2.5 kW microwave power.

Low Hydrogen Silicon Carbon Nitride Cap for High Performance Sub-10 nm Cu-Low k Interconnect

The metallization of integrated circuits for high performance CMOS devices involves the use of copper with low-k or ultra low-k dielectrics to reduce RC delay and cross talk in devices. For the 90nm to 14 nm CMOS device nodes, conventional silicon nitride was replaced by new dielectric barrier low k materials such as SiCN, C-Rich SiCN and SiNO (1-6). As devices scale down to <=10 nm dimension, further reduction in cap thickness is required for the Cu barrier while maintaining sufficient mechanical strength, low leakage, high dielectric breakdown, and fabrication integration robustness. In a previous report (6), we showed that a single layer SiCNx film deposited by plasma enhanced CVD with TMS+NH3 is still robust down to around 15-20 nm thickness range. This paper presents the development of the second generation robust Low Hydrogen SiCN to enable cap thickness reduction to <=10 nm by simply altering/reducing the hydrogen concentration in the SiCN film composition. EXPERIMENT The low hydrogen SiCNx films were deposited in a commercial high throughput production worthy 13.6 MHz RF 300 mm Plasma Chemical Vapor Deposition process (PECVD) system at 350 C using a combination of Trimethyl Silane (TMS) + Ammonia (NH3) + Hydrogen precursors with excellent uniformity (1 sigma < 1 %). The as-deposited films were analyzed using various electrical , mechanical and chemical analyses to study the film's properties and compositions, Table 1. An oxidation resistance test (6) was done after the barrier film/copper blanket stack was annealed at 310°C for 24 hours in ambient atmosphere. Multi-level 7nm copper interconnect structures were built for Electro-migration (EM) and Time Dependent Dielectric Breakdown (TDDB) reliability measurement (150-300°C). RESULTS and DISCUSSION Table 1 summarizes SiCN and Low H SiCN cap film properties and device performance. Overall, the low H SiCN cap has better electrical, mechanical, and device reliability performance than the standard SiCN cap. The low H SiCN film has higher density, modulus, hardness and significantly higher compressive stress, both as-deposited and post 5 minutes direct UV cure. Compositional analysis shows that PECVD SiCNx cap films deposited with the addition of hydrogen precursor actually have less hydrogen than films deposited without hydrogen under the same optimized deposition condition. Film deposition rates decrease slightly at higher hydrogen flow rate in the TMS+NH3+H2 precursor chemistry. The reduced deposition rate and the hydrogen reduction in the film’s bulk are attributed to the increase removal (etching) of weakly bonded -Si-Hx and -N-Hy species in the film during the plasma deposition process. FTIR analysis shows that Si-C and Si-N bonding density increases in the low H SiCN dielectric, which is consistent with the increase in film density, modulus and harness. A minor reduction in the dielectric constant, similar breakdown voltage and reduced leakage are observed for the low H SiCN cap. Figure 1 shows a typical Scanning Transmission Electron Micrograph (STEM) of a 3nm Co/10 nm Low H SiCN cap on a Copper Metal2 7nm interconnect structure. This Cu/Co/Low H SiCNxcap structure achieves 4-10X better EM/TDDB reliability versus a similar structure with the standardcap (Table 1). A Scanning Electron Micrograph (SEM) of the patterned surface after annealing at 310°C for 24 hours in ambient atmosphere (Figure 1) shows that the 10 nm Low H SiCN cap has excellent Cu Oxidation properties with no sign of Cu Oxidation. CONCLUSIONS Low hydrogen SiCN dielectrics with improved mechanical, oxidation and Cu diffusion barrier properties versus standard SiCN were deposited using TMS, NH3 and H2. The new robust low hydrogen SiCN dielectric cap film showed a significant increase in Si-C and Si-N bonding density and a reliability performance improvement in 7 nm Cu interconnect structures at <=10 nm thickness . This enables significant improvement in capacitance, reliability and Cu_low k nano device performance. Acknowledgment This work was performed by the Research Alliance Teams at various IBM Research and Development Facilities. The author would like to thank B. Peethala for some analysis and A. Grill for discussion. REFERENCES [1] L. Xia, M. Naik, H. Xu, V. Zubkov, R. Bhatia, C. Peterson, M. Spuller, and H. M’Saad, Proceeding of Advanced Metallization for Devices and Circuits, (2006) pp. 169. [2] S.G. Lee et al, Jpn. J. Appl. Phys., 40, 2663 (2001). [3] Al Grill, Steve Gate, Son Nguyen, D. Priyadarshin, E Tood Ryan; Appl. Phys. Rev. 1, 011306 (2014). [4] Son V. Nguyen et al., Electrochem. Soc. Transaction 2014, Volume 61, issue 3, pp.17-28. [5] C.Yang et al., IEEE Electron Device Letter, Vol 33, No, 4, pp.588-560 (2012). [6] Son Nguyen et al., Electrochem. Soc. Transaction. 2010, Volume: 33, Issue: 12, pp.137-145. Figure 1

Suppression of silicon clusters using a grid mesh under DC bias

Si clusters generated during the plasma chemical vapor deposition (CVD) process have a great influence on the quality of the fabricated films. In particular, in hydrogenated amorphous silicon thin films (a-Si:H) used for thin film solar cells, Si clusters are mainly responsible for light-induced degradation. In this study, we investigated the amount of clusters incorporated into thin films using a quartz crystal microbalance (QCM) and specially designed cluster eliminating filters, and investigated the effect of the DC grid mesh in preventing cluster incorporation. Experimental results showed that as the applied voltage of the grid mesh, which is placed between the electrode and the QCM, decreased, the number of clusters incorporated into the film decreased. This is due to the electrostatic force from the grid mesh bias, and this method is expected to contribute to the fabrication of high-quality thin films by preventing Si cluster incorporation.

Synthesis and characterization of boron doped diamond/β-SiC composite films

Boron doped diamond/β-SiC composite films with a conductive diamond phase separated by the insulating β-SiC phase are fabricated by the microwave plasma chemical vapor deposition process. By manipulating the gas phase composition during the film deposition, the boron incorporation and diamond/β-SiC ratio in the composite film are well controlled. Scanning electron microscopy, transmission electron microscopy, Raman and X-ray diffraction measurements are carried out to study the structural composition of the films. It is observed that the introduction of boron during the growth process does not affect the independent growth of diamond and β-SiC crystals with high crystal quality. Scanning spreading resistance microscopy measurements confirm the presence of the conductive diamond phase and the insulating β-SiC phase in the film. The observed differences in the conductivities between diamond and β-SiC are explained by the different boron acceptor levels in diamond and β-SiC crystals. Cyclic voltammetry measurements are carried out to study the electrochemical property of the films. Our results demonstrate that boron doped diamond/β-SiC composite films are a good candidate for electroanalysis applications whereby exploiting diamond's high chemical and dimensional stability as well as its excellent electrochemical properties.

Corrosion resistance of NiTi shape memory alloy after hybrid surface treatment using low-temperature plasma

This article presents a study of the structure, surface roughness and corrosion resistance of composite layers consisting of a layer of Ti(ON) titanium oxynitride with a surface zone of amorphous carbon modified with nitrogen and hydrogen. They were produced on NiTi alloy in a hybrid process combining oxidation in low-temperature plasma and Radio Frequency Chemical Vapor Deposition process (RFCVD). Ti(ON)+a-CNH type composite layers can be produced in temperatures below 300 °C, i.e. in conditions ensuring that the specific properties of NiTi alloys, namely shape memory and superelasticity, are maintained. They provide a significant increase in corrosion resistance and may be produced on specimens having complex shapes, which is of great importance in the case of possible application as medical implants.

(Invited) Role of Charges in Non-Classical Crystallization of Thin Films and Nanostructures in the Plasma CVD Process

Extensive studies have been made on non-classical crystallization, which refers to the crystal growth by the building unit of nanoparticles. In parallel with the non-classical crystallization in the crystal growth in solution, the non-classical crystallization in the gas phase synthesis of thin films and nanostructures by chemical vapor deposition (CVD) and some physical vapor deposition (PVD) has been studied extensively. Here, the charged nanoparticles (CNPs) are spontaneously generated in the gas phase and become the building block of thin films and nanostructures. Charged nanoparticle-based crystallization appears to be very general, including the growth of diamond, Si, ZrO2, GaN, ZnO films as well as nanowires. The generation of CNPs in the gas phase was experimentally confirmed in many systems and their mass distribution was shown to play a decisive role in the microstructure evolution of films, nanowires, and nanotubes. The fact that CNPs can be a building block of crystals without leaving any void behind and of nanowires with smooth surface indicates that CNPs are quasi-solid, having a liquid-like property in diffusion. This means that the charge enhances the atomic diffusion, which is a newly discovered physical phenomenon. This means again that charge weakens the bond strength. Small nanoparticles can be liquid-like even if singly charged but large nanoparticles should be multiply charged to be liquid-like. Based on this understanding, the microcrystalline silicon without an amorphous incubation layer could be deposited on a glass substrate at 320oC and on a polymer substrate at 200oC. Using the liquid-like property of CNPs, the epitaxial growth of silicon was successfully achieved at 550oC by the plasma CVD process. Weakening of bond strength by charges would enhance chemical reactions at low temperature, which can explain the low temperature decomposition in the plasma CVD process. Charge-enhanced diffusion would favor the crystallization and produce charged crystalline nanoparticles at low temperature in the plasma, which explain the low temperature deposition of crystalline films by the plasma CVD process. References N.M. Hwang and D.K. Lee, J. Phys. D: Appl. Phys. 43, 483001 (2010) (Topical Review).A. Badzian and N.M. Hwang, Diamond: Low-Pressure Synthesis, Ref. Module of Mater. Sci. & Mater. Eng. (2016).

SiC-assisted growth of tubular graphenic cones with carbon nanotube tips

SiC-assisted growth of tubular graphenic cones (TGCs) with carbon nanotube tip is achieved with high yield in the microwave plasma chemical vapor deposition process. No pre-existing metal or semiconductor catalyst particles are required on the substrate prior to the deposition process. Instead, the in situ grown SiC crystallites serve as the catalyst for the growth of TGCs. Thanks to the easy formation of SiC on various substrates, the process is compatible with a wide range of substrates, i.e. Si, diamond, 2H–SiC, GaN, and SiO2, but not only limited to them. In addition to developing the approach, the mechanism for the formation of TGCs is also proposed. When Si is used as the substrate, the 3C–SiC crystallites grow epitaxially on the surface, which further initiate the epitaxial growth of graphene with its basal plane parallel to the {111} planes of 3C–SiC. The further expansion of graphene is constrained by the 3C–SiC crystallites, leading to the formation of curved graphene layers, i.e. onion-like or bowl-shaped graphene-based carbon. These curved graphene layers are believed to be the possible nucleation sites for the growth of TGCs. Inclusion of boron in the gas phase promotes the growth rates and the final yields of TGCs.

Cytotoxicity of Boron-Doped Nanocrystalline Diamond Films Prepared by Microwave Plasma Chemical Vapor Deposition**supported by the Open Foundation of State Key Laboratory of Electronic Thin Films and Integrated Devices (University of Electronic Science and Technology of China) (No. KFJJ201313)

Boron-doped nanocrystalline diamond (NCD) exhibits extraordinary mechanical properties and chemical stability, making it highly suitable for biomedical applications. For implant materials, the impact of boron-doped NCD films on the character of cell growth (i.e., adhesion, proliferation) is very important. Boron-doped NCD films with resistivity of 10−2 Ω·cm were grown on Si substrates by the microwave plasma chemical vapor deposition (MPCVD) process with H2 bubbled B2O3. The crystal structure, diamond character, surface morphology, and surface roughness of the boron-doped NCD films were analyzed using different characterization methods, such as X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and atomic force microscopy (AFM). The contact potential difference and possible boron distribution within the film were studied with a scanning kelvin force microscope (SKFM). The cytotoxicity of films was studied by in vitro tests, including fluorescence microscopy, SEM and MTT assay. Results indicated that the surface roughness value of NCD films was 56.6 nm and boron was probably accumulated at the boundaries between diamond agglomerates. MG-63 cells adhered well and exhibited a significant growth on the surface of films, suggesting that the boron-doped NCD films were non-toxic to cells.

Argon–germane in situ plasma clean for reduced temperature Ge on Si epitaxy by high density plasma chemical vapor deposition

Demand for integration of near infrared optoelectronic functionality with silicon complementary metal oxide semiconductor (CMOS) technology has for many years motivated the investigation of low temperature germanium on silicon deposition processes. This work describes the development of a high density plasma chemical vapor deposition process that uses a low temperature (&amp;lt;460 °C) in situ germane/argon plasma surface preparation step for epitaxial growth of germanium on silicon. It is shown that the germane/argon plasma treatment sufficiently removes SiOx and carbon at the surface to enable germanium epitaxy. The use of this surface preparation step demonstrates an alternative way to produce germanium epitaxy at reduced temperatures, a key enabler for increased flexibility of integration with CMOS back-end-of-line fabrication.