Remote Plasma Chemical Vapor Deposition Research Articles

Direct growth of highly oriented GaN thin films on silicon by remote plasma CVD

We report on low-temperature (500 °C) and low-pressure (0.3 mbar) direct growth of GaN thin films on silicon (100) substrates using remote plasma chemical vapour deposition (RP-CVD). In the custom-designed reactor, an RF inductively coupled plasma is generated remotely from the substrate’s area to facilitate the decomposition of group-V precursor, N2 with added H2, while group-III precursor trimethylgallium (TMGa), is directly injected into the growth chamber mixed with H2 carrier gas. Growth parameters such as RF power, process pressure and gas flow rates have been optimized to achieve a film growth rate of about 0.6 µm h−1. Several characterization techniques were used to investigate the plasma and the properties of the grown thin films in terms of their crystallinity, morphology, topography, and composition. The films are highly textured with a preferential orientation along the c-axis of the wurtzite structure. They present a small roughness in the nanometer range and a columnar microstructure with a grain size of one hundred nanometer, and a gallium polarity (+c plane oriented). Rutherford backscattering spectrometry and nuclear reaction analysis show that the chemical composition is homogeneous through the depth of the layer, with a III/V ratio close to 1, a very low content of oxygen (below the detection limit ∼1%) and a carbon content up to 11%. It was shown that the increase of plasma power helps to reduce this carbon contamination down to 8%. This research paves the way for a growth method compatible with cost reduction of III–V thin film production achieved through reduced gas consumption facilitated by RP-CVD operation at low pressure.

Remote plasma chemical vapor deposition of silicon oxycarbide film with a styrene-containing precursor and in situ O2 plasma treatment

In this paper, a study was conducted on silicon oxycarbide thin-film deposition using remote plasma chemical vapor deposition. A di-methyldimethoxysilane)2styrene (MDMS)2styrene precursor and CH4 plasma were used in the deposition process, and in situ oxygen plasma treatment was performed to control the carbon content and properties of the thin film. During the deposition process, the thin-film growth rate was found to be almost constant regardless of in situ plasma treatment. This means that in situ oxygen plasma treatment had no significant effect on thin-film growth itself. Auger electron spectroscopy analysis revealed that the carbon content of the deposited thin film was 43 % when only deposition was performed, but could be lowered to 3 % by in situ oxygen plasma treatment, which demonstrated that the carbon content can be controlled in a relatively wide range. X-ray photoelectron spectroscopy showed that it was possible to preserve SiC bonds even as the oxygen content increased with the number of in situ plasma treatments. The refractive index increased from 1.33 to 1.49, indicating a decrease in the number of pores and an increase in density. Meanwhile, the dielectric constant increased with the oxygen content, but did not exceed 3.9 due to the SiC bond structure. As the pore size decreased, the leakage current tended to decrease to 9.51 × 10−9 A/cm2 in an electric field of 1 MV/cm, and the breakdown voltage increased. Finally, it was possible to improve the etching characteristic through plasma treatment by lowering the wet etch rate from 78 to 19 Å/min.

Low-temperature fabrication of silicon nitride thin films from a SiH4+N2 gas mixture by controlling SiNx nanoparticle growth in multi-hollow remote plasma chemical vapor deposition

High-quality amorphous silicon nitride (SiNx) thin films were fabricated by the controlled growth of nanoparticles during SiH4+N2 multi-hollow remote plasma chemical vapor deposition (CVD) at low substrate temperature 100 °C. Measurements from quartz crystal microbalances showed that a higher amount of nanoparticle incorporation in the SiNx film corresponded to a higher ratio of N/Si in the film, implying that the nanoparticles were nitrided in the plasma phase. We controlled the size of the nanoparticles by tuning the gas flow ratio of N2/SiH4 and the total gas flow rate. Transmission electron microscopy and energy-dispersive X-ray spectroscopy showed that smaller nanoparticles in the plasma led to a higher ratio of N/Si in the film and a lower hydrogen content. We attribute these results to the low heat capacity and large specific surface area of the nanoparticles, which enabled active chemical reactions on their surface in the plasma.

Amorphous silicon carbonitride (a‐SiCN) thin film coatings by remote plasma chemical vapor deposition using organosilicon precursor: Effect of substrate temperature

AbstractThe study on amorphous hydrogenated silicon carbonitride (a‐SiCN) thin film coatings produced by remote plasma chemical vapor deposition from 1,1,3,3‐tetramethyldisilazane as single‐source compound is reviewed. The RP was generated using three extreme compositions of the H2 + N2 upstream‐gas mixture with a different nitrogen content CN2 = [N2]/([H2] + [N2]). The films were deposited using plasma generated from with pure hydrogen (CN2 = 0), pure nitrogen (CN2 = 1), and a mixture of H2 + N2 with a nitrogen content of CN2 = 0.88, corresponding to the maxima present in the NH hydronitrene emission intensity curve and film deposition yield curve. The films deposited at different substrate temperatures TS varied in the range of 30–400°C were characterized in terms of their deposition rate and yield, chemical structure, surface roughness, density, refractive index, hardness, elasticity, resistance to wear, and friction coefficient. The relationships of the structure and properties of the films controlled by the substrate temperature were determined and discussed. In view of their good mechanical properties, a‐SiCN films produced using hydrogen as plasma feeding gas appear to be very excellent coatings for improving surface properties of engineering materials and for many other advanced technological applications.

Amorphous silicon carbonitride a‐SiCN thin film coatings by remote plasma chemical vapor deposition using organosilicon precursor: Effect of plasma composition

AbstractOur study on amorphous hydrogenated silicon carbonitride thin films produced by remote plasma chemical vapor deposition (RP‐CVD) from 1,1,3,3‐tetramethyldisilazane as a single‐source compound using the H2 + N2 upstream‐gas‐mixture for generation of microwave plasma are reviewed. The effect of nitrogen content in the H2 + N2 mixture fed to a plasma on the rate and yield of the RP‐CVD process, chemical structure, surface morphology, and properties of a‐SiCN films deposited at a constant substrate temperature of TS = 300°C is described. The deposited films were characterized in terms of their chemical structure, surface roughness, density, refractive index, hardness, elasticity, resistance to wear, and friction coefficient. Due to their properties, a‐SiCN films appear to be very promising coatings for improving the surface mechanics of engineering materials used in advanced technologies.

Low temperature epitaxial technology for GaN-based materials

<p indent="0mm">The band gap of GaN-based semiconductor materials covers the entire visible light band and has excellent physical and chemical properties, which makes it widely used in the fabrication of optoelectronic devices, power electronic devices, and radio frequency and microwave devices. Traditional GaN-based materials are usually epitaxially grown on high-temperature-resistant single-crystalline substrates such as sapphire, silicon, or silicon carbide using metal-organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), or hydride vapor phase epitaxy (HVPE). These epitaxial techniques usually use high temperature to crack the precursors involved in the reaction. With the deepening of informatization and intelligentization, the common demands for low-cost and flexibility of opto(electronic) devices have emerged. On one hand, the display technology is a key link to realize information exchange and intelligence. Moving towards an intelligent society requires further reduction of the display cost per unit area. At the same time, the wearable and portable flexible display technology also has broad application prospects. In addition, solid-state lighting has gradually penetrated into every corner of human life with the improvement of device performance. The application scenarios are rich and colorful. Judging from this, low-cost surface light sources will be a strong competitor for the next generation of lighting technology routes. On the other hand, reducing the fabrication cost of electronic devices per unit area also needs more attention in the future. For example, flexible electronic skin has broad and huge application prospects in artificial limbs, robotics, medical detection and diagnosis, etc., which has also spawned the demand for low-cost flexible sensors. It can be seen that the common requirements of the above applications for core components are low cost and flexibility, which is also one of the main development directions of the next generation of (opto)electronic devices. Amorphous substrates (such as glass, plastic, metal, polyethylene terephthalate (PET), polydimethylsiloxane (PDMS), etc.) that are cheap and easy to fabricate are ideal choices, but a significant disadvantage is that amorphous substrates cannot withstand high growth temperatures. Therefore, the need for low-temperature epitaxy of GaN-based materials has arisen, that is, a kind of epitaxy equipment that can use external electric field energy to crack the reaction precursor at low temperatures. So far, a variety of low-temperature epitaxial technologies have been developed based on the physical vapor deposition (PVD) and the chemical vapor deposition (CVD), and preliminary research results have been obtained. The PVD techniques include reactive magnetron sputtering, plasma-assisted MBE (PA-MBE), pulsed laser deposition (PLD), pulsed sputtering deposition (PSD), laser MBE (LMBE), etc. The CVD techniques include remote plasma CVD (RPCVD), migration enhanced afterglow CVD (MEA-CVD), remote plasma-enhanced MOCVD (RPEMOCVD), radical-enhanced MOCVD (REMOCVD), electron cyclotron resonance plasma-enhanced MOCVD (ECR-PEMOCVD), inductive coupled plasma MOCVD (ICP-MOCVD), etc. In this paper, the two types of low-temperature epitaxial technologies are introduced in detail, including the device structure, working conditions and related epitaxial growth results, and the characteristics of each type of technology are summarized. Finally, the development prospect of low temperature epitaxial technologies is prospected, and the focus of future research is pointed out. We hope this work can provide a useful reference for the low temperature epitaxy research of GaN-based materials.

Synthesis and Characterization of Boron Thin Films Using Chemical and Physical Vapor Depositions

Boron as thin film material is of relevance for use in modern micro- and nano-fabrication technology. In this research boron thin films are realized by a number of physical and chemical deposition methods, including magnetron sputtering, electron-beam evaporation, plasma enhanced chemical vapor deposition (CVD), thermal/non-plasma CVD, remote plasma CVD and atmospheric pressure CVD. Various physical, mechanical and chemical characteristics of these boron thin films are investigated, i.e., deposition rate, uniformity, roughness, stress, composition, defectivity and chemical resistance. Boron films realized by plasma enhanced chemical vapor deposition (PECVD) are found to be inert for conventional wet chemical etchants and have the lowest amount of defects, which makes this the best candidate to be integrated into the micro-fabrication processes. By varying the deposition parameters in the PECVD process, the influences of plasma power, pressure and precursor inflow on the deposition rate and intrinsic stress are further explored. Utilization of PECVD boron films as hard mask for wet etching is demonstrated by means of patterning followed by selective structuring of the silicon substrate, which shows that PECVD boron thin films can be successfully applied for micro-fabrication.

Hard silicon carbonitride thin‐film coatings produced by remote hydrogen plasma chemical vapor deposition using aminosilane and silazane precursors. 1: Deposition mechanism, chemical structure, and surface morphology

AbstractAmorphous silicon carbonitride films were produced by remote hydrogen microwave plasma chemical vapor deposition (RP‐CVD) using aminosilanes: (dimethylamino)dimethylsilane, bis(dimethylamino)methylsilane, and tris(dimethylamino)silane, as well as disilazanes: 1,1,3,3‐tetramethyldisilazane and 1,3‐bis(dimethylsilyl)‐2,2,4,4‐tetramethylcyclodisilazane as single‐source precursors. The effect of substrate temperature (TS) on the rate and yield of the RP‐CVD process, chemical composition, chemical structure, and surface morphology of resulting films is reported. The temperature dependencies of thickness‐based growth rate and growth yield of the film imply that for a low substrate temperature range (TS = 30–200°C), deposition rate and yield are limited by desorption of film‐forming precursors from a growth surface, whereas for a high substrate temperature range (TS = 200–400°C), the rate and yield values, independent of the temperature, are nearly constant and the RP‐CVD is a nonthermally activated process. The increase of the substrate temperature from 30°C to 400°C causes the elimination of organic groups from the film and the formation of a silicon carbonitride network structure with a predominant content of Si–N nitridic and Si–C carbidic bonds. On the basis of structural study and literature data, hypothetical elementary reactions contributing to the film formation process are postulated. The films were found to be morphologically homogeneous, defect‐free materials exhibiting very small surface roughness, which varied in a narrow range of values.

Hard silicon carbonitride thin‐film coatings by remote hydrogen plasma chemical vapor deposition using aminosilane and silazane precursors. 2: Physical, optical, and mechanical properties of deposited films

AbstractPhysical, optical, and mechanical properties of silicon carbonitride (a‐SiCN) films produced by remote hydrogen plasma chemical vapor deposition (RP‐CVD) using aminosilane and disilazane precursors are examined in relation to their chemical structure. The films deposited at different temperatures (30–400°C) were characterized in terms of their density, refractive index, optical bandgap, photoluminescence, adhesion to a substrate, hardness, elastic modulus resistance to wear (predicted from the “plasticity index” values), and friction coefficient. Reasonable structural dependencies of film properties were determined using the relative integrated intensities of the infrared absorption bands from the Si−N and Si−C bonds, and the X‐ray photoelectron spectroscopy Si2p band from the Si−C bonds (controlled by substrate temperature) evaluated in the first part of this study. In view of their good mechanical properties, a‐SiCN films seem to be useful coatings for improving surface mechanics of engineering materials for advanced technology.

Correlation between the Carbon Nanotube Growth Rate and Byproducts in Antenna-Type Remote Plasma Chemical Vapor Deposition Observed by Vacuum Ultraviolet Absorption Spectroscopy.

For sp2 or sp3 carbon material growth, it is important to investigate the precursors or intermediates just before growth. In this study, the density of ethylene (C2 H4 ) outside the plasma discharge space and just before reaching the carbon nanotube (CNT) growth region is investigated by vacuum ultraviolet absorption spectroscopy for plasma discharge in an antenna-type remote plasma chemical vapor deposition with a CH4 /H2 system, with which the growth of very long (≈0.5 cm) CNT forests is achieved. Single-wall CNT forests have the potential for application as electrodes in battery cells, vertical wiring for high current applications, and thermal interface materials. It is observed that the plasma discharge decomposes the CH4 source gas and forms C2 Hx species, which reversibly reform to C2 H4 in the plasma-off state. In addition, the density of the formed C2 H4 has a strong correlation to the CNT growth rate. Therefore, the C2 H4 density is a good indicator of the density of C2 Hx species for CNT growth in the CH4 /H2 plasma system.

Point‐Arc Remote Plasma Chemical Vapor Deposition for High‐Quality Single‐Crystal Diamond Selective Growth

Selective growth techniques are believed to be the most effective approaches in the fabrication of diamond devices. Herein, the contamination from antenna and mask damage that causes poor performance in electronic applications is overcome with a high‐quality diamond film on Ib (100) substrate, obtained by utilizing point‐arc remote microwave plasma chemical vapor deposition (MPCVD). Scanning electron microscope (SEM) images and energy dispersive X‐ray (EDX) mapping suggest that the diamond nucleation and selective growth occurred only in unmasked regions. Crystalline quality is evaluated by Raman spectra. Mo concentration from the antenna is detected with secondary ion mass spectroscopy (SIMS) at only a background level in the selectively grown diamond, indicating that the films are free of contaminant from the antenna, at three orders of magnitude lower than the impurity concentration in films selectively grown by typical hot filament CVD. Moreover, the moderate growth rate (approximately 50 nm h−1) enables high reproducibility, which is of great importance for the precise control thickness of the selective growth layer, and thus the proposed method offers significant potential for the architecture modification of diamond devices.

Plasma Enabled Conformal and Damage Free Encapsulation of Fragile Molecular Matter: from Surface‐Supported to On‐Device Nanostructures

AbstractDamage‐free encapsulation of molecular structures with functional nanolayers is crucial to protect nanodevices from environmental exposure. With nanoscale electronic, optoelectronic, photonic, sensing, and other nanodevices based on atomically thin and fragile organic matter shrinking in size, it becomes increasingly challenging to develop nanoencapsulation that is simultaneously conformal at atomic scale and does not damage fragile molecular networks, while delivering added device functionality. This work presents an effective, plasma‐enabled, potentially universal approach to produce highly conformal multifunctional organic films to encapsulate atomically thin graphene layers and metalorganic nanowires, without affecting their molecular structure and atomic bonding. Deposition of adamantane precursor and gentle remote plasma chemical vapor deposition are synergized to assemble molecular fragments and cage‐like building blocks and completely encapsulate not only the molecular structures, but also the growth substrates and device elements upon nanowire integration. The films are insulating, transparent, and conformal at sub‐nanometer scale even on near‐tip high‐curvature areas of high‐aspect‐ratio nanowires. The encapsulated structures are multifunctional and provide effective electric isolation, chemical and environmental protection, and transparency in the near‐UV–visible–near‐infrared range. This single‐step, solvent‐free remote‐plasma approach preserves and guides molecular building blocks thus opening new avenues for precise, atomically conformal nanofabrication of fragile nanoscale matter with multiple functionalities.

Surface modification of silicon oxycarbide films produced by remote hydrogen microwave plasma chemical vapour deposition from tetramethyldisiloxane precursor

The motivation for this contribution is the search for thin-film silicon oxycarbide (SiOC) materials suitable for modern electronics with good chemical/thermal stability, good barrier properties and conformal coverage, which can be deposited on rigid and flexible substrates, and whose surface can be organically functionalized. Two types of thin SiOC films of very different nature, such as polymer-like and ceramic-like, were fabricated by means of remote hydrogen microwave plasma chemical vapour deposition (RP-CVD) from 1,1,3,3–tetramethyldisiloxane (TMDSO). The RP-CVD coatings deposited on a silicon substrate were then modified by treatment with a direct radiofrequency (RF) plasma process induced in a mixture of argon and water vapour (Ar/H2O), which resulted in the surface activation through the formation of highly reactive silanol groups (SiOH). In this process a silicon oxide layer (SiOx) was also formed, and its growth was examined by FTIR, XPS and ellipsometry. The growth of the SiOx structure reduces the film thickness of silicon oxycarbide. Activation of the film surface is completed in <10 s. In the next modification step, the RP-CVD films were silanized by immobilizing (3-aminopropyl)triethoxysilane (APTES). Attachment of APTES molecules to the activated surface of SiOC films was observed with the development of an additional layer of SiOx on the surface. The silanization with APTES vapour under nitrogen allowed the formation of 10 nm-thick condensate. The AFM microscopic examination showed that the deposited APTES layers are homogeneous without aggregates specific for conventional silanization from the solution. The final modification of RP-CVD films was achieved by functionalization with an organic fluorescent probe, which involves the covalent attachment of pyrene to amino group of APTES using hydroxyimide ester linkage (PyNHS). The results of the present study proved that the chemical functionalization of thin silicon oxycarbide films was achieved.

Silicon Carbide, Silicon Carbonitride, and Silicon Oxycarbide Thin Films Formed by Remote Hydrogen Microwave Plasma CVD

Background: Silicon-based thin films produced by remote microwave hydrogen plasma chemical vapor deposition (RP-CVD) from 1,1,4,4-tetramethyldisilaethylene, 1,1,3,3-tetramethyldisiloxane and 1,1,3,3- tetramethyldisilazane precursors are compared. The structure of these compounds differs in atomic composition of the central unit which links the two dimethylhydrosilane moieties. Objective: The effect of temperature on the kinetics of film growth rate induced by RP CVD process, chemical composition and structure as well as same characteristic parameters of resulting amorphous hydrogenated silicon carbide (a-SiC:H), silicon oxycarbide (a-SiOC:H), and silicon carbonitride (a-SiCN:H) films is discussed. Conclusion: It was found that RP CVD process is controlled by adsorption, in which there are two temperature ranges for the formation of the CVD layers. At low-temperature range soft polymer-like material is formed containing organic groups whereas at high-temperature range a transformation to high-density ceramic- like material occurs. Based upon the results of the studies, mechanisms of the initiation step, as well as growth and crosslinking steps in the film formation during RP CVD deposition are proposed. The films were also characterized in terms of their representative properties, such as density, refractive index and biocompatibility. Owing to the high density, defect-free surface and excellent optical parameters the films may be useful as coatings for optoelectronics applications and in medicine for steel implants. Keywords: Remote hydrogen plasma, CVD process, silicon-based precursor, silicon carbide film, silicon oxycarbide film, silicon carbonitride film, properties of thin films, biocompatibility.

Amorphous silicon carbonitride thin‐film coatings produced by remote nitrogen microwave plasma chemical vapour deposition using organosilicon precursor

Amorphous silicon carbonitride (a‐SiCN) films were produced by remote nitrogen plasma chemical vapour deposition (RP‐CVD) from bis(dimethylamino)methylsilane precursor. The effect of substrate temperature (TS) on the kinetics of RP‐CVD, chemical structure, surface morphology and some properties of the resulting films is reported. The TS dependence of film growth rate implies that RP‐CVD is an adsorption‐controlled process. Fourier transform infrared spectroscopic examination revealed that an increase in TS from 30 to 400°C involves the elimination of organic moieties from the film and the formation of Si─C and Si─N network structure. The films were characterized in terms of their surface roughness and basic physical and optical properties, such as density and refractive index, respectively. Reasonably good relationships between the structural parameters represented by relative integrated intensity of infrared absorption bands from the Si─C and Si─N bonds (controlled by TS) and the film properties are determined. Due to their small surface roughness, high density and high refractive index, the a‐SiCN films produced at TS ≥ 350°C would seem to be useful protective coatings for metals and optical devices.

Fabricating High-Performance Silicon Thin-Film Transistor by Meniscus Force Mediated Layer Transfer Technique

INTRODUCTION. If such a Silicon (Si) metal-oxide-semiconductor field-effect transistor (MOSFET) technology, namely, high-performance single crystalline silicon (c-Si) MOSFETs formed locally at the required position at low temperature (150°C or less) on flexible substrates, were established, so-called “flexible electronics” could be further advanced. Moreover, this technology could also be applied to system integration, namely, simultaneously mounting different devices such as integrated circuits and sensors[1]. We have proposed a novel layer transfer of the (100)-oriented c-Si thin film to a flexible substrate at very low process temperature[2]. In this study, by applying above-mentioned technology, the performance of flexible MOSFETs fabricated by using a c-Si film transferred by meniscus force was verified experimentally. EXPERIMENTAL. The SOI layer [p-type Si(100), 10-30 W∙cm] was patterned to form a 3-µm-wide and 5-µm-long dog-bone shape with 20×20 µm2 square regions at both ends. This pattern is applicable to MOSFET fabrication to form a source, a channel, and a drain. To form supporting columns, holes with size of 2 × 2 µm2 were made at intervals of 3 µm in the square regions. The 300 nm-thick buried-oxide (BOX) layer was isotropically etched by 33% hydrofluoric acid at room temperature for 90 seconds by using the patterned SOI layer as a mask for the midair cavity. As a result of the etching of the BOX layer below the patterned SOI layer, the narrow SiO2 columns can be formed underneath both end regions of the film. Figure 1 schematically shows the meniscus force(F=πR 2 γ[(1/R)-(2cosθE/H)]+2πR2γ sinθE ) mediated layer transfer (MLT) of SOI layer to a flexible substrate[2]. The starting and counter PET substrates were in close face-to-face contact with the filling water, and these substrates were heated on a hot plate at 80°C. RESULTS AND DISCUSSION. When the starting SOI wafer and the PET substrate were separated, it was confirmed that the original form and position of the SOI layer were completely maintained after the film transfer. The electron-backscatter-diffraction (EBSD) pattern map confirms that a (100)-oriented c-Si thin film was successfully formed on PET substrate at 80°C. Here, to confirm the adaptability of this layer transfer technique to thin-film devices, MOSFET were fabricated on a PET substrate. The source and drain regions were implanted with phosphorus ions at a dosage of 1×1015 cm-2. To control the threshold voltage, boron ions were injected (at a dosage of 1×1011 cm-2) into the channel region. After impurities in the source, channel, and drain regions were activated by heating at 1000 ºC in nitrogen ambient for 10 minutes, the BOX layer was isotropically etched by 33% hydrofluoric acid at room temperature for 90 seconds by using the patterned SOI layer as a mask for the midair cavity. As a result of the etching of the BOX layer below the patterned SOI layer, the narrow SiO2 columns can be formed underneath both end regions of the film. Here, the key process is the thermal oxidation of the SOI layer on the midair cavity. An 11-nm-thick gate insulator was formed on a SOI wafer temperature at 1000 ºC in dry oxygen ambient for four minutes[3]. By thermally oxidizing the SOI layer, the SOI layer can be covered on both surfaces with SiO2. After that, the forming gas annealing was performed at 400 ºC in a 3%-hydrogen/nitrogen mixture for 30 min. The thermal oxidation and subsequent hydrogen anneal ensure a good MOS interface, and the SiO2 layer works as a “blocking” layer that blocks contamination from PET. After the SOI layer was transferred to the PET substrate by MLT technique, a 200-nm-thick SiO2 film was deposited at 130 ºC by remote plasma chemical vapor deposition (RPCVD). After the contact holes are opened, the gate, source, and drain electrodes are formed by aluminum evaporation and wet etching. The MOSFET dimensions are length (L) of 3.7 µm and width (W) of 3 µm, and the maximum temperature of the fabrication process is 130ºC. Figure 2 shows Id-Vg characteristics of the MOSFETs fabricated on a transferred Si film. The MOSFET dimensions are L = 3.7 µm and W = 3 µm. The MOSFET showed a mobility of 343 cm2V-1s-1. A CKNOWLEDGEMENTS.A part of this work was supported by Research Institute for Nanodevice and Bio Systems, Hiroshima University and Funding Program for Next Generation World-Leading Researchers (NEXT Program) from the Japan Society for the Promotion of Science (JSPS). This work was supported by JSPS KAKENHI Grant Number 252156. REFERENCES. [1] T. Fukushima, et. al., IEDM Tech. Dig., 1 (2008). [2] K. Sakaike el al., Jpn. J. Appl. Phys. 53, 018004 (2014). [3] K. Sakaike el al., Appl. Phys. Lett., 103, 233510 (2014).

Remote hydrogen microwave plasma chemical vapor deposition from methylsilane precursors. 1. Growth mechanism and chemical structure of deposited a-SiC:H films

Amorphous hydrogenated silicon carbide (a-SiC:H) thin films were produced by remote microwave hydrogen plasma chemical vapor deposition (RP-CVD) using dimethylsilane (DMS) and trimethylsilane (TrMS) as single-source precursors. The effect of substrate temperature on the rate of RP-CVD process, chemical composition and chemical structure of resulting a-SiC:H films is reported. The Arrhenius plots of substrate temperature dependencies of the thickness-based film growth rate imply that the investigated RP-CVD for DMS precursor is a non-thermally activated process, whereas for TrMS precursor is an adsorption-controlled process. The examination of the a-SiC:H films performed by means of Auger electron spectroscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared absorption spectroscopy, revealed that the increase in the substrate temperature from 30°C to 400°C causes the elimination of organic moieties from the films and the formation of Si-carbidic network structures. On the basis of the results of structural study the elementary reactions involved in the formation of a-SiC:H films are proposed.

Remote hydrogen microwave plasma chemical vapor deposition from methylsilane precursors. 2. Surface morphology and properties of deposited a-SiC:H films

Amorphous hydrogenated silicon carbide (a-SiC:H) films produced by remote microwave hydrogen plasma chemical vapor deposition from dimethylsilane and trimethylsilane precursors were characterized in terms of their basic useful properties including surface morphology, conformality of coverage, density, refractive index, optical absorption (absorption coefficient and optical bandgap) adhesion to a substrate, and friction coefficient. The effect of substrate temperature (varied in the range TS=30–400°C) on the properties of a-SiC:H films is reported. In view of the scanning electron microscopy and atomic force microscopy examinations the films were found to be morphologically homogeneous materials exhibiting excellent conformality of coverage and small surface roughness, which drop with rising TS to a small value of 0.9nm at TS=400°C. The relationships between the film compositional and structural parameters, expressed, respectively, by the atomic ratio Si/C, and the relative integrated intensities of the absorption IR band from the SiC bonds (controlled by TS), were determined. Due to their good conformality of coverage, strong adhesion to a substrate, very low friction coefficient, and excellent optical transparency in a wide range of wavelength a-SiC:H films produced from trimethylsilane precursor at high substrate temperature regime (TS=300–400°C) seem to be useful as scratch-resistant protective coatings for optical glass elements and various metal surfaces.

Gas Barrier Properties of Diamond-like Carbon Films Synthesized by Using Remote Type Microwave Plasma CVD under Sub-ambient Atmospheric Pressure

Diamond-like carbon (DLC) films were synthesized on polyethylene (PE) substrates with a remote type microwave plasma chemical vapor deposition (MPCVD) apparatus at 10 kPa. We investigated the effect of source gas flow rate and microwave power on oxygen transmission rate of DLC films. Acetylene (C2H2) and argon (Ar) gas were used for source gas and carrier gas, respectively. From the result of contact-type profiler and atomic force microscope, oxygen transmission rate decreased as thickness increased and surface roughness decreased with increasing C2H2 flow rate. The oxygen transmission rate of DLC film synthesized at the C2H2 flow rate of 0.50 l/min and the microwave power of 1.0 kW on 300 μm thick PE substrates was 141 cc/m2·day, while that of uncoated PE substrates was 247 cc/m2·day.

Hard a-SiC:H films formed by remote hydrogen microwave plasma chemical vapor deposition using a novel single-source precursor

The a-SiC:H films were produced by remote hydrogen plasma chemical vapor deposition (RP-CVD) from bis(dimethylsilyl)ethane as a novel single-source precursor. The effect of substrate temperature (TS) on the kinetics of RP-CVD, chemical composition, structure, surface morphology, and properties of resulting films (density, refractive index, photoluminescence, hardness, elasticity, and resistance to wear) is reported. The TS dependence of film growth rate implies that RP-CVD is an adsorption controlled process. The increase of TS from 30°C to 400°C causes the elimination of organic moieties from the film and the formation of SiC network structure. The relationships between the relative integrated intensity of SiC IR band and film properties were determined. The films deposited at TS=300°C appear to be very hard materials exhibiting small surface roughness and low intensity of blue photoluminescence (PL). They seem to be suitable protective coatings for metals to increase their wear strength.