Boron Carbon Nitride Films Research Articles

High quality boron carbon nitride/ZnO-nanorods p-n heterojunctions based on magnetron sputtered boron carbon nitride films

Boron carbon nitride (BCN) films were synthesized on Si (100) and fused silica substrates by radio-frequency magnetron sputtering from a B4C target in an Ar/N2 gas mixture. The BCN films were amorphous, and they exhibited an optical band gap of ∼1.0 eV and p-type conductivity. The BCN films were over-coated with ZnO nanorod arrays using hydrothermal synthesis to form BCN/ZnO-nanorods p-n heterojunctions, exhibiting a rectification ratio of 1500 at bias voltages of ±5 V.

Preparation and Characterization of Boron Carbon Nitride Films on High Speed Steel Surface

In this paper, we deposited BCN films on high speed steel (HSS) substrate by magnetron sputtering. The structure and composition of the films were analyzed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The tribological properties of the films was studied by ball-on-disc tribological test. Results show that BCN films have a certain antifriction effect, which is influenced by RF target power and substrate bias.

Studies on Dielectric Properties of Annealed Reactively Co-Sputtered Bcn Thin Films

The main concern in the Ultra Large Scale Integrated (ULSI) semiconductor devices is the reduction of signal propagation delay. This delay ( ) is the product of electrical resistance of wiring metal and the parasitic capacitance of the Inter dielectric layer (IDL). The motivation behind the boron carbon nitride (BCN) ternary compounds is their similarities in the structure and difference in properties between graphite and hexagonal boron nitride (h-BN). Both theoretical calculations and experimental studies show that BCN compounds exhibit excellent mechanical, optical and electrical properties [1], [2]. It has been reported that the addition of carbon atoms to BN films is effective in reducing the dielectric constant. Also the structure of BCN film has a strong impact on dielectric constant [3]. The BCN deposition by chemical vapor deposition (CVD) has been reported [4], but in this work reactive co-sputtering is performed to deposit BCN thin films. The co-sputtering helps in the creation of films which gives more freedom to vary the composition when compared to single target sputtering. Thickness uniformity and the film quality are better when using co-sputtering.In this work, we are depositing BCN thin films on oxidized silicon wafer substrates using two targets namely B4C and BN using RF power and DC power respectively at different N2/Ar gas flow ratios. A thin film of titanium (Ti) was deposited on it and another layer of Aluminum was deposited on top of the titanium layer to form a metal/insulator/semiconductor (MIS) device. This titanium layer acts as the barrier layer against the aluminum migration into BCN at higher temperatures during annealing. The dielectric constant value was found from capacitance-voltage (C-V) characteristics.REFERENCES[1] I. Caretti, J.M. Albella, I. Jiménez, Diamond Relat. Mater., 16 (2007), p. 1445[2] A. Perrone, A.P. Caricato, A. Luches, M. Dinescu, C. Ghica, V. Sandu, A.Andrei , Appl. Surf. Sci., 133 (1998), p. 239 [3] T.Sugino, Y. Etou, T. Tai, Jpn. and H. Mori, Appl. Phys. Lett. 80, 649 (2002) [4] J. Yu and E. G. Wang, Appl. Phys. Lett. 74, 2848 (1999)

Effect of annealing on the mechanical and scratch properties of BCN films obtained by magnetron sputtering deposition

Abstract Boron-carbon-nitride (BCN) films have been fabricated by direct current unbalanced magnetron sputtering. Boron carbide/graphite compound and a mixture of nitrogen and argon are used as target and carrier gas, respectively, during BCN synthesis. The obtained BCN films are annealed at different temperatures under vacuum condition. The effect of annealing temperature on the structure, mechanical properties and scratch behavior of the BCN films has been investigated. The results indicate that no decomposition products are found even the BCN films are annealed at 1000 °C. The hardness and elastic modulus of the films decrease with the increase of annealing temperatures. The BCN film annealed at 600 °C has the strongest scratch resistance. The friction coefficient of all BCN films is in range of 0.05 to 0.15.

Hardness Studies of RF Sputtered Deposited BCN Thin Films

In today’s technological advancement of ULSI integration, the inter-dielectric layer (IDL) with small RC delays needs low-k materials which are sturdy enough to withstand mechanical stress posed by multilayer devices. Using organic polymers that are porous in nature can achieve dielectric values as low as 2, but these cannot withstand considerable mechanical stress. Boron Nitride (BN) films can achieve low-k values around and hardness comparable to diamond [1][2]. BN is hygroscopic in nature. In this respect carbon can be added to the BN structure to produce Boron Carbon Nitride (BCN) films as the possible substitute for BN. The minimum dielectric constant achieved by plasma assisted chemical vapor deposition for a BCN thin film was reported to be 1.9. [2] The BCN films are also instrumental in suppressing the Cu migration [3]. The Young’s modulus of BCN films are reported well above 20 GPa making it one of the suitable options for low-k materials [4]. In the present work, BCN films were deposited by RF sputtering of boron carbide (BC) target in nitrogen ambient with argon. The films were deposited under various N2/Ar gas flow ratios. FTIR measurements were performed to find the chemical bonds of the deposited films. Investigations were performed to evaluate the Hardness (H) and Young’s modulus (E) of the deposited films under various conditions.

Optical Studies of Reactively Co-Sputtered Bcn Thin Films

The motivation behind the boron carbon nitride (BCN) ternary compounds is their similarities in the structure and difference in properties between graphite and hexagonal boron nitride (h-BN). Both theoretical calculations and experimental studies show that BCN compounds exhibit excellent mechanical, optical and electrical properties [1], [2]. In particular, the possibility to control the band gap (EG ) by atomic composition and structure makes them good candidates for the application in electronic and photonic devices [3], [4].The optical characteristic like transmittance is improved with initial incorporation of nitrogen into the film composition and has a stable trend with further increase in nitrogen concentration. Also the optical band gap of BCN (2.2eV-3eV) increased with incorporation of nitrogen and said to follow a linear trend between B4C (2eV) and BN (4eV) [5]. The co-sputtering helps in creation of films with graded indexes of refraction as well. It gives more freedom to vary the composition as when compared to single target sputtering. Thickness uniformity and the film quality are better when using co-sputtering.Dual target approach will be conducted to prepare BCN tin films. In this work we are depositing BCN thin films on quartz substrates using two targets namely B4C and BN using RF power and DC power respectively at different N2/Ar gas flow ratios. Also the input power for B4C and BN are varied to achieve different composition of the BCN thin films to control the optical properties. The optical properties like transmission and reflectance are studied using the UV-visible spectrophotometer. The optical absorption is studied by Tauc plot which is instrumental in finding the optical band gap of the material and the refractive index.REFERENCES[1] I. Caretti, J.M. Albella, I. Jiménez, Diamond Relat. Mater., 16 (2007), p. 1445[2] A. Perrone, A.P. Caricato, A. Luches, M. Dinescu, C. Ghica, V. Sandu, A.Andrei , Appl. Surf. Sci., 133 (1998), p. 239 [3] M.O. Watanabe, S. Itoh, K. Mizushima, T. Sasaki, J. Appl. Phys., 78 (1995), p. 2880 [4] P.R. Fitzpatrick, J.G. Ekerdt, J. Vac, Sci. Technol. A, 26 (2008), p. 1397[5] Optical characterization of BCN films deposited at various N2/Ar gas flow ratios by RF magnetron sputtering.

Investigation on Electrical Properties of RF Sputtered Deposited BCN Thin Films

The ever increasing advancements in semiconductor technology and continuous scaling of CMOS devices mandate the need for new dielectric materials with low-k values. The interconnect delay can be reduced not only by the resistance of the conductor but also by decreasing the capacitance of dielectric layer. A wiring metal with low resistivity and a high quality insulating film with a low dielectric constant may lead to a reduction of the wiring capacitance. Boron carbon nitride (BCN) films are prepared by reactive magnetron sputtering from a B4C target and deposited to make metal-insulator-metal (MIM) sandwich structures using aluminum as the top and bottom electrodes. BCN films are deposited at various N2/Ar gas flow ratios, substrate temperatures and process pressures. The electrical characterization of the MIM devices includes capacitance vs. voltage (C-V), current vs voltage, and breakdown voltage characteristics. The above characterizations are performed as a function of deposition parameters.

Mechanical properties and bonding structure of boron carbon nitride films synthesized by dual ion beam sputtering

The BCN films were synthesized on Si (110) wafers by using dual ion beam sputtering deposition from boron carbide target. The influences of ion assist source energy and N2 relative flow rate on the surface roughness, mechanical properties and chemical bonding structure of BCN films were investigated systematically. The surface roughness was measured using non-contact optical surface profilometer and the mechanical properties of BCN films were evaluated with nano-indenter. The BCN films were characterized by using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS), respectively. The results showed that the BCN films' surface roughness varied in the range of 5–15 nm, and their hardness and reduced elastic modulus fluctuated in the scope of 18–29 GPa and 192–229 GPa, respectively. When the BCN films' surface roughness varied in the range of 8–12 nm, the values of hardness and reduced elastic modulus were fluctuated slightly. The BCN films with the smoothest surface (Ra = 5 nm) and the highest hardness of 28 GPa were obtained at the ion assist source energy of 200 eV and the N2 relative flow rate of 50%. The BCN films were amorphous and contained several bonding states such as B–N, B–C and C–N with B–C–N hybridization.

Bias in bonding behavior among boron, carbon, and nitrogen atoms in ion implanted a-BN, a-BC, and diamond like carbon films

In this study, we implanted N+ and N2+ ions into sputter deposited amorphous boron carbide (a-BC) and diamond like carbon (DLC) thin films in an effort to understand the chemical bonding involved and investigate possible phase separation routes in boron carbon nitride (BCN) films. In addition, we investigated the effect of implanted C+ ions in sputter deposited amorphous boron nitride (a-BN) films. Implanted ion energies for all ion species were set at 40 KeV. Implanted films were then analyzed using x-ray photoelectron spectroscopy (XPS). The changes in the chemical composition and bonding chemistry due to ion-implantation were examined at different depths of the films using sequential ion-beam etching and high resolution XPS analysis cycles. A comparative analysis has been made with the results from sputter deposited BCN films suggesting that implanted nitrogen and carbon atoms behaved very similar to nitrogen and carbon atoms in sputter deposited BCN films. We found that implanted nitrogen atoms would prefer bonding to carbon atoms in the films only if there is no boron atom in the vicinity or after all available boron atoms have been saturated with nitrogen. Implanted carbon atoms also preferred to either bond with available boron atoms or, more likely bonded with other implanted carbon atoms. These results were also supported by ab-initio density functional theory calculations which indicated that carbon-carbon bonds were energetically preferable to carbon-boron and carbon-nitrogen bonds.

Effect of Target Power and Bias on Adhesive Force of BCN Films

Boron carbon nitride (BCN) is a new type of super-hard material with excellent properties, and is very suitable for use as a wear-resistant protective coating and solid lubricant. In this report, we prepared BCN films on YG8 cemented carbide substrate by magnetron sputtering. The structure and composition of the films were analyzed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The adhesiveness of the films was studied by scratch test. Results from these analyses show that BCN films deposited on the YG8 substrate has good adhesion properties. We also demonstrated that target power and substrate bias have a great impact on the adhesiveness of the films, and reasonable process parameters can improve the adhesiveness of the films.

Influence of atomic bonds on electrical property of boron carbon nitride films synthesized by remote plasma-assisted chemical vapor deposition

Boron carbon nitride (BCN) films are synthesized with various growth conditions by remote plasma-assisted chemical vapor deposition method. The chemical bonding in the BCN film is modified by the growth condition. Optical and electrical properties are investigated for BCN films with various chemical bonding. Electrical characterization is carried out for the BCN films which have the same bandgap energy and different C composition ratio and have the same C composition ratio and different bandgap energy.

Influence of the methyl group on the dielectric constant of boron carbon nitride films containing it

LSI interconnect insulators made using low dielectric constant (low-k) materials are required for high performance devices with a small RC delay. We investigated a boron carbon nitride film containing the methyl group (Me–BCN) using tris-di-methyl-amino-boron (TMAB: B[N(CH 3) 2] 3) gas as a low-k material. In addition, we studied the influence of the methyl group on the dielectric constant (k-value) and the properties of the Me–BCN films. It was found that the k-value of the Me–BCN films decreases with increasing number of C–H bonds due to the methyl group (CH 3). The number of O–H bonds due to water incorporation is suppressed by increasing the number of C–H bonds. Consequently, we suggested that a lower k-value can be realized by the suppression of water invasion by a hydrophobic surface due to methyl bonds. Thus, the control of the methyl group is important to achieve a low-k material using Me–BCN films.

Electron Emission Properties of Hetero-Junction Structured Carbon Nanotube Microtips Coated With BN And CN Thin Films

Boron nitride (BN) and carbon nitride (CN) films, which have relatively low work functions and commonly exhibit negative electron affinity behaviors, were coated on carbon nanotubes (CNTs) by magnetron sputtering. The CNTs were directly grown on metal-tip (tungsten, approximately 500nm in diameter at the summit part) substrates by inductively coupled plasma-chemical vapor deposition (ICP-CVD). The variations in the morphology and microstructure of CNTs due to coating of the BN and CN films were analyzed by field-emission scanning electron microscopy (FE-SEM). The energy dispersive x-ray (EDX) spectroscopy and Raman spectroscopy were used to identify the existence of the coated layers (CN and BN) on CNTs. The electron-emission properties of the BN-coated and CN-coated CNT-emitters were characterized using a high-vacuum field emission measurement system, in terms of their maximum emission currents (Imax) at 1kV and turn-on voltage (Von) for approaching 1µA. The results showed that the Imax current was significantly increased and the Von voltage were remarkably reduced by the coating of CN or BN films. The measured values of Imax-Von were as follows; 176µA-500V for the 5nm CN-coated emitter and 289µA-540V for the 2nm BN-coated emitter, respectively, while the Imax-Von of the as-grown (i.e., uncoated) emitter was 134µA-620V. In addition, the CNT emitters coated with thin CN or BN films also showed much better long-term (up to 25h) stability behaviors in electron emission, as compared with the conventional CNT emitter.

Effect of nitrogen pressure on structure and optical properties of pulsed laser deposited BCN thin films

Amorphous boron carbon nitride (BCN) thin films were deposited on Si (100) and quartz substrates by laser ablation of a boron carbide (B 4C) target in nitrogen atmosphere. The effects of the nitrogen pre ssure ( p N 2 ) on the film deposition rate, composition, structure and optical properties were investigated. The film deposition rate was measured by a surface profiler, which increased from 3.4 to 6.25 nm/min at elevated p N 2 . Structure and composition of the films were investigated by X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared (FTIR) spectroscopy. FTIR and XPS analyses indicated that the as-deposited BCN films contained B–C, N–C and B–N chemical bonds, implying the formation of ternary BCN compounds. The nitrogen content in the films increased gradually and then saturated up to ∼ 26 at.% at 10 Pa p N 2 . The optical band gap ( E g) increased from 3.78 to 3.92 eV with increasing p N 2 from 2 to 15 Pa. The evolution of E g is in accordance with the change of film compositions and bonding states.

Effect of the radio-frequency power on the dielectric properties of hydrogen-containing boron carbon nitride films deposited by plasma-assisted chemical vapor deposition using tris(dimethylamino)boron gas

We investigated the properties of boron carbon nitride film containing hydrogen (BCNH film) deposited using tris(dimethylamino)boron as the source gas. The dielectric constant (k) of BCNH film decreases with decreasing radio-frequency plasma power used for deposition, and can be as low as 1.8 at 10 W. Thermal desorption spectroscopy analysis shows that the film contains a large amount of hydrogen. Fourier transform infrared spectroscopy shows an absorption band at 2960 cm−1, attributed to the asymmetrical stretching mode of C–H in the methyl group. It is thought that increasing the number of C–H bonds, which have a low polarizability, can achieve a lower k value.

Atomic bonds in boron carbon nitride films synthesized by remote plasma-assisted chemical vapor deposition

Boron carbon nitride (BCN) films are synthesized by remote plasma-assisted chemical vapor deposition (RPCVD) method. The present experimental apparatus is featured by introducing BCl 3 gas near the substrate without mixing to plasma consisting of N 2 and CH 4 gases. Two sample groups of the BCN films are prepared. One is grown with various CH 4 flow rates, and another is grown with various BCl 3 flow rates. The composition ratio of the constituent atoms, atomic bonds and optical bandgap are investigated. C composition ratio of the BCN film increases with increasing CH 4 flow rate, leading to a reduction in the optical bandgap with increasing C composition ratio. On the other hand, it is found that no significant variation in the composition ratio occurs for the BCN films grown with various BCl 3 flow rates and that the optical bandgap decreases with increasing BCl 3 flow rate. This behavior of the optical bandgap is related to a change of the atomic bonds in the BCN film grown with various BCl 3 flow rates.

Influence of assisted ion energy on surface roughness and mechanical properties of boron carbon nitride films synthesized by DIBSD

The BCN thin films were produced by dual ion beam sputtering deposition (DIBSD). The influence of assisted ion energy on surface roughness and mechanical properties of BCN films were investigated. The surface roughness was determined by atomic force microscopy (AFM) and the mechanical properties of BCN firms were evaluated by nano-indentation in N 2 gas. The composition, structure and chemical bonding of the BCN thin films were analyzed by using energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), laser Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR). These films appeared as amorphous structure. As a result, the BCN films with the smoothest surface ( R a = 0.35 nm and R p–v = 4.4 nm) and the highest nano-hardness of 30.1 GPa and elastic modulus of 232.6 GPa were obtained at 200 eV and 12 mA with N 2:Ar = 1:1, and the chemical composition of this BCN film was 81 at.% B, 14 at.% C and 5 at.% N. Moreover, several bonding states such as B–N, B–C and C–N were observed in BCN thin films.

Influence of Cu electroplating solutions on boron carbon nitride (BCN) film

Cu electroplating is required for the fabrication of Cu/low-k interconnections. The permeation of a plating solution into low-k films during Cu electroplating is a serious challenge for 45-nm nodes and more complex devices. We investigated the influence of Cu electroplating solutions on boron carbon nitride (BCN) as a low-k film. After dipping it into a Cu electroplating solution that contained additives, the BCN film's hydrophilic surface changed to a hydrophobic surface, and the incorporation of water into the BCN film was suppressed by surfactant adsorption. Sulfuric residue was detected on the BCN sample by thermal desorption spectroscopy after treatment in the Cu electroplating solution with additives; however, it was found through electrical measurements that this solution did not affect the leakage current or the dielectric constant of the BCN film. We successfully fabricated an electroplating Cu layer on a BCN film with good adhesion, and we believe that this BCN film is a sufficiently useful material for Cu/BCN integration in LSI.

Influence of oxygen plasma treatment on boron carbon nitride film composition

Variations in the composition and bonds of boron carbon nitride (BCN) film caused due to an oxygen (O2) plasma ashing process are investigated for a low dielectric constant (low-k) insulating film for next generation LSI devices. The O2 plasma treatment is preformed for BCN samples with various C compositions. The etching rate of BCN films with an O2 plasma decreases with increasing C composition. The reaction of O atoms is suppressed in the BCN film with a high C composition. B–N and B–C bonds with lower bond energies are easily broken by the O2 plasma and replaced by the generation of B–O, N–O, and C–O bonds. The B-atom concentration for all samples is decreased significantly by the O2 plasma treatment. Ion bombardment may play a more dominant role than the O-atom reaction in the etching of the BCN film. The existence of C–N bonds with a high bonding energy may suppress etching and incorporation of O atoms.

Properties of boron carbon nitride (BCN) film after plasma ashing

Dry etching and resist ashing of a low dielectric constant interlayer (low- k) are required for the formation of a trench structure, which is necessary for the fabrication of damascene interconnections using materials such as Cu. We investigated the properties of boron carbon nitride (BCN) film after plasma ashing by H 2/N 2 gas and O 2 gas and compared with porous SiOC (P-SiOC) thin film. It is found that by ashing with O 2 or N 2/H 2 plasma, BCN film composition does not change and the film damage is also little in the view points of leakage currents and dielectric constant. Hence, it is understood that both N 2/H 2 or O 2 gas plasma can be used for interconnection process of with BCN low- k film.