Growth Rate Of Thin Films Research Articles

Effect of Bipolar Charging of SiH4 on the Growth Rate and Crystallinity of Silicon Films Grown in the Atmospheric Pressure Chemical Vapor Deposition Process

Increasing the growth rate of thin films and enhancing the film quality have been an issue in the semiconductor manufacturing process. To improve those properties, conventionally the deposition temperature in reactor was increased or a catalyst was added to decompose precursors at low temperature. Here, a new technology utilizing a bipolar carbon fiber ionizer (CFI) was used to achieve a high growth rate and quality of silicon films. The deposition behavior of atmospheric pressure chemical vapor deposition silicon films deposited with and without the bipolar CFI system was compared. The growth rate of silicon films deposited at 450 °C, 500 °C, 700 °C, 900 °C and 1100 °C with the bipolar CFI system was 3.4, 5.6, 3.2, 3.3 and 1.3 times higher than deposited silicon film without the bipolar CFI system. The bipolar CFI system could also improve the crystallinity of the silicon film deposited at 900 °C.

Research of the influence of vacuum deposition on the growth rate of MoS2 films

The research results of the working pressure and discharge power influence on the growth rate of molybdenum disulfide thin films on silicon substrates during magnetron sputtering of the target in vacuum are presented. Based on experimental data, an empirical model has been developed that relates the film growth rate to argon pressure and discharge power on a magnetron sputtering system.

Development of antireflective coatings based on SiO2/Si3N4 on textured silicon for heterojunction solar cells

The technology of antireflective coatings formation on textured silicon by magnetron sputtering was developed. The growth rates of individuals thin films were determined as well as their refractive indexes. According to the results obtained an antireflective coating based on SiO2/Si3N4 on textured silicon with a thickness of SiO2 68 nm and Si3N4 of 74 nm showed the lowest reflection.

Ar flow-rate effect for low-resistivity Al/Ti/Al Ohmic contact to n-ZnO thin films

<p class="Abstract">The Ar flow rate effect on the electrical and optical properties of the sputtered Al-doped ZnO thins films were investigated. It was shown that a strong X-ray peak from (002) and (004) planes is dominant, suggesting that most grains have <em>c</em>-axis perpendicular to the substrate surface. The (002)-ZnO and (004)-ZnO peaks were measured at 2q = 34.12<sup>0</sup>, and 71.85<sup>0</sup>, respectively. It was also found that the growth rate of the Al-doped ZnO thin films increases when the sputtering power is increased. The transmittance of these film are strongly dependent on the sputtering power with the maximum transmittance of 92% was obtained at the sputtering power of 150 W and 50 sccm of Ar flow rate. The resistivity of the films is decreases as the Ar flow rate is increased. The lowest resistivity of 9.74 x 10<sup>-4</sup> W.cm was obtained at the films with Ar flow rate of 80 sccm. The mobility increases with the Ar flow rate increases. The carrier concentration also indicates the same pattern as the mobility. The transmittance of Al-doped ZnO thin films is also strongly dependent on the Ar flow rate. It was also observed the variation of contact resistivity of Al/Ti/Al to Al-doped n-ZnO thin films. The specific contact resistivity <em>r<sub>c</sub></em> of 1.8x10<sup>−5</sup> W.cm<sup>2</sup> was obtained at 150 nm-thick Al.</p>

Surface-orientation-dependent growth of SrRuO3 epitaxial thin films

The growth of epitaxial transition metal oxide thin films depends on various parameters including the substrate temperature, oxygen partial pressure, kinetics of incoming adatoms, Gibbs free energy, and surface energy. Naturally, the change in the crystallographic surface orientation with a distinctive surface energy also influences the growth rate and growth mode of the epitaxial thin films substantially. Using perovskite SrRuO3 as a model system, we studied the growth characteristics by changing the surface orientation of the SrTiO3 substrate. Employing X-ray diffraction and surface atomic and Kelvin probe force microscopy (KPFM), we observed a systematic decrease in the growth rate and a modification in the growth mode from a two-dimensional growth to a three-dimensional island growth with the change in the surface orientation from (100) to (110) to (111). A spin-polarized density functional theory calculation demonstrated the corresponding difference in the surface energy, which was also confirmed experimentally by the KPFM measurements. The difference in the surface energy could explain the observed change in the growth kinetics, based on the modified classical nucleation theory. A combinatorial method using a polycrystalline epitaxial thin film was employed to generalize our understanding of the crystallographic surface-orientation-dependent thin film growth.

Remote Plasma Atomic Layer Deposition of SiNx Using Cyclosilazane and H2/N2 Plasma

Silicon nitride (SiNx) thin films using 1,3-di-isopropylamino-2,4-dimethylcyclosilazane (CSN-2) and N2 plasma were investigated. The growth rate of SiNx thin films was saturated in the range of 200–500 °C, yielding approximately 0.38 Å/cycle, and featuring a wide process window. The physical and chemical properties of the SiNx films were investigated as a function of deposition temperature. As temperature was increased, transmission electron microscopy (TEM) analysis confirmed that a conformal thin film was obtained. Also, we developed a three-step process in which the H2 plasma step was introduced before the N2 plasma step. In order to investigate the effect of H2 plasma, we evaluated the growth rate, step coverage, and wet etch rate according to H2 plasma exposure time (10–30 s). As a result, the side step coverage increased from 82% to 105% and the bottom step coverages increased from 90% to 110% in the narrow pattern. By increasing the H2 plasma to 30 s, the wet etch rate was 32 Å/min, which is much lower than the case of only N2 plasma (43 Å/min).

Analysis on Characteristics of ZnO Surface Acoustic Wave with and without Micro-Structures.

In this paper, we fabricate a surface acoustic wave (SAW) device with micro-structures on a zinc oxide (ZnO) thin film and measure its signal response. The manufacturing processes of the SAW device include the fabrication of micro-structures of a SAW element and its interdigital transducer by silicon micro-machining and the fabrication of a thin film of ZnO by RF magnetron sputtering. We, then, measure the SAW properties. This research investigates the properties of sputtered thin films for various amounts of O2/(Ar + O2) using Zn and ZnO targets. Regardless of target, the growth rate of the ZnO thin film decreases as the oxygen content increases. When the SAW is sputtered ZnO thin film using 30% oxygen, the digital signal of the SAW has better performance. The measurement signal of the SAW with micro-structures is similar to that without micro-structures.

The Effect of Carrier Gas and Reactor Pressure on Gallium Nitride Growth in MOCVD Manufacturing Process

Gallium nitride (GaN) is an attractive material for manufacturing light emitting diodes and other electronic devices due to its wide band-gap and superb optoelectronic performance. The quality of GaN thin film determines the reliability and durability of these devices. Metal-organic chemical vapor deposition (MOCVD) is a common technique used to fabricate high-quality GaN thin films. In this paper, GaN growth rate and uniformity in a vertical rotating disk MOCVD reactor are investigated on the basis of a three-dimensional computational fluid dynamics (CFD) model. GaN growth rate is investigated under the influence of reactor pressure, precursor concentration ratio, and composition of the carrier gas mixture. The numerical simulation shows that the carrier gas mixture and the reactor pressure have significant effects on growth rate and uniformity of GaN thin films. It is also found that an appropriate mixture of N2 and H2 may be employed as the carrier gas to improve the flow field characteristic in the reactor. This results in an improved crystal growth of GaN thin films.

Low pressure chemical vapor deposition of β-Ga2O3 thin films: Dependence on growth parameters

Low pressure chemical vapor deposition (LPCVD) has been used to produce high quality β-Ga2O3 materials with controllable n-type doping. In this work, we focus on the studies of key LPCVD growth parameters for β-Ga2O3 thin films, including oxygen/carrier gas flow rates, growth temperature, pressure, and the substrate to Ga crucible distance. These growth parameters play important roles during the LPCVD β-Ga2O3 growth and determine the thin film growth rate, n-type dopant incorporation, and electron mobilities. The dependence of the growth parameters on LPCVD of β-Ga2O3 was carried out on both conventional c-plane sapphire and 6 degree off-axis (toward ⟨11-20⟩ direction) sapphire substrates. To better understand the precursor transport and gas phase reaction process during the LPCVD growth, a numerical model for evaluating the growth rate was developed by using a finite element method and taking into account the gas flow rate, chamber pressure, and chamber geometry. The results from this work can provide guidance for the optimization of the LPCVD growth of β-Ga2O3 with targeted growth rate, surface morphology, doping concentration, and mobility. In addition, β-Ga2O3 grown on off-axis c-sapphire substrates features with faster growth rates with higher electron mobilities within a wide growth window.

N-doped Al2O3 thin films deposited by atomic layer deposition

The present study focused on nitrogen doped Al2O3 thin films using atomic layer deposition, varying the deposition temperature from 55 to 170 °C. Al2O3 thin film growth rate and electrical properties were mostly dependent on deposition temperature. Nitrogen concentration decreased from 2.7 to 2.4% with increasing deposition temperature. X-ray photoelectron spectroscopic analysis confirmed that nitrogen doping in Al2O3 decreased formation of oxygen related defects, including non-lattice oxygen. Surface morphology analyses also showed that N-doping reduced Al2O3 film surface roughness. Reduced oxygen related defects significantly reduced leakage current by 1000 times when comparing with as-deposited films. Minimum leakage current (5 × 10−10 A/cm2) was observed for N-doped Al2O3 film deposited at 170 °C and post-annealed at 400 °C, including a decrease by 10 times through N-doping.

Investigation of plasma dynamics during the growth of amorphous titanium dioxide thin films

We have grown amorphous titanium dioxide thin films by reactive DC sputtering method using a different argon/oxygen partial pressure at a room temperature. The plasma dynamics of the process, reactive and sputtered gas particles was investigated via optical emission spectroscopy. We then studied the correlations between the plasma states and the structural/optical properties of the films. The growth rate and morphology of the titanium dioxide thin films turned out to be contingent with the population and the energy profile of Ar, O, and TiO plasma. In particular, the films grown under energetic TiO plasma have shown a direct band-to-band transition with an optical energy band gap up to ∼4.2 eV.

Synthesis of ALD Iridium Thin Films on Silicon and Monel K-500 Steel Substrates

Iridium (Ir) thin films have been extensively investigated for a variety of applications. Ir is a potential optical material for Fresnel zone X-ray microchannel plates, and inductive grid filters. It is also a noble metal making it well suited to corrosion resistance in harsh environments Atomic Layer Deposition (ALD) is considered a special case of chemical vapor deposition (CVD) in that two different chemical precursor materials are alternately introduced into a vacuum chamber where a chemical reaction occurs on the surface of the substrate. This method of thin film growth is self-limiting and conformal and consequently results in precise layer thickness control, stoichiometry, composition, and uniformity across a large surface area. Advantages that are unique to ALD include the ability to grow conformal thin films across complex geometries, and the relatively low temperatures required to achieve film growth. In this work, iridium metal films were synthesized on silicon (Si) and Monel K-500 alloy substrates by ALD using Iridium (III) acetylacetonate known as Ir(acac)3 or [CH3COCH=C(O-)CH3]3 Ir as precursor 1, and industrial grade O2 as oxidizing reactant. The solid Ir precursor was heated to 150 °C, and the substrate temperature was varied to establish an optimum growth window. The lowest temperature in which Ir growth was found is 200 °C, and the thin film growth rate increased as a function of temperature up to 250 °C. Higher temperatures have not yet been attempted due to equipment constraints. The Monel K-500 steel alloy flat discs were cut from commercially available Monel K-500 bars of ~1 inch diameter. In this study we report on the successful synthesis of Ir films on Si and Monel K-500 substrates. Detailed characterization has been performed using X-ray diffraction (XRD) techniques, atomic force microscopy (AFM), and field emission scanning electron microscopy (FE-SEM) of samples which have been notched with focused ion beam (FIB) techniques for cross-sectional film thickness measurements as revealed in Figure 1. The polycrystalline ALD Iridium film exhibited good chemisorption and adhesion to native oxide covered Si substrates, with hydroxyl surface termination. However even with the absence of a SiO2 surface film, the ALD synthesis of Iridium metal films worked equally well on the Monel K-500 steel alloy flat disc substrates and yielded excellent surface coverage.

Nucleation and growth of CuCl thin films on commercially available SnO2/glass substrates by the sublimation method

Studies on cuprous chloride (CuCl) sublimation, thin film deposition, and growth on commercially available tin oxide coated glass substrates were performed by adjusting substrate and vapor source thermal parameters. A systematic method for measuring CuCl film thicknesses was implemented using scanning white light interferometry. Furthermore, structural characteristics of the films were evaluated via scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Thickness measurements at established locations determined the growth rates of CuCl thin films with respect to deposition conditions. SEM and EDS results revealed that localized clusters (islanding) occurred at the initial stages of growth. As growth continued, the islands began to coalesce and develop nonuniform CuCl grain networks across the substrate. The results support the Volmer–Weber growth mode as the primary mechanism responsible for such growth behavior.

Effect of complexing agent on the chemically deposited ZnS thin film

Zinc sulfide (ZnS) thin films have been deposited onto fluorine doped tin oxide and microscopic glass substrates from an aqueous alkaline reaction by chemical bath deposition. The effect of concentrations of hydrazine hydrate (HyH) (complexing agent) on the deposit is studied. X-ray analysis confirm the growth of nanocrystalline ZnS thin films with reflections (111), (220) and (311) correspond to cubic crystalline phase. TEM results support the growth of cubic ZnS layers. The energy band gap was successfully tailored from 2.77 to 3.80 eV. Photoluminescence study indicates a strong band-edge emission with some defect like vacancies. It was also noticed that HyH plays an important role on the nucleation. The remarkable improvement in the growth rate of ZnS thin films have been observed upon increasing the contents of HyH. Nearly stoichiometric ZnS layer was obtained upon annealing prepared with 2.5 M HyH. The crystallinity was found to be increased upon annealing the layers. The ideality factor for the ZnS layers prepared with 0 and 1.0 M HyH were obtained ~1.71 and 1.24, respectively. The capacitance–voltage plots behave according to Schottky–Mott theory. The doping concentrations ~1017 and 1018 cm−3 were calculated for the layers deposited with 0 and 1.0 M HyH, respectively.

Disilane addition versus silane-hydrogen flow rate effect on the PECVD of silicon thin films

The effect of small disilane addition to the silane/hydrogen mixture and of the total silane/hydrogen flow rate on the silicon thin film growth rate and crystallinity were investigated. The study was performed by using simplified gas phase chemistry model along with plasma diagnostics such as electrical and deposition rate measurements. The results showed that even small disilane addition induces an increase in the electron density, silane electron-induced dissociation rate, and film growth rate. The increase in the total flow rate caused a linear increase in the film growth rate despite the negligible effect on the discharge microscopic parameters. Similar deposition rates and crystallinities were achieved with both disilane addition and increase in the flow rate, but the deposition efficiency was much higher in the case of disilane addition. The simplified gas phase chemistry model indicated an increase in the silyl production rate either with the disilane addition or the increase in the flow rate. Almost the same silyl production rates were calculated for both parameters, but for the disilane addition case, this was achieved with much less silicon containing molecules in the gas feed. Finally, the increase in the silyl production rate combined to the almost constant hydrogen atoms production, and consumption rate is estimated as the main reason for the drop in the crystallinity with the increase in disilane fraction in the mixture or the total flow rate.

High‐Rate Deposition of Stoichiometric Compounds by Reactive Magnetron Sputtering at Oblique Angles

Target poisoning in reactive magnetron sputtering deposition of thin films is an undesired phenomenon, well known for causing a drastic fall of the process efficiency. We demonstrate that when this technique is operated at oblique angles, films with composition raging from pure metallic to stoichiometric compound can be grown in non‐poisoned conditions, thus avoiding most of the associated drawbacks. We have employed amorphous TiOx, although the presented results can be easily extrapolated to other materials and conditions. It is found that the proposed method improves 400% the growth rate of TiO2 thin films.

Influence of Deposition Time on Bonding and Morphology of Amorphous Carbon Nitride Thin Films

Amorphous carbon nitride (a-CNx) is a well-known material that can be used in various applications such as coating for hard disk, wear resistant, humidity sensor and others. In this research, a-CNx thin films have been deposited by using radio frequency-plasma enhanced chemical vapor deposition (RF-PECVD) with the mixing of pure methane (CH4) and nitrogen (N2). The gas ratio of CH4/N2, electrode distance, pressure and temperature of deposition is kept constant while deposition time is allowed to vary from 30 to 150 minutes. Raman spectroscopy and field emission scanning electron microscopy (FESEM) have been used to study the bonding and morphology of these films respectively. An increase in deposition time resulted with thedecrease in sp2 content in the a-CNx thin films. Theincrease in the Id/Ig intensity ratio with the increase in deposition time can be explained by the reducing size of graphitic cluster. Long deposition time retarded the growth rate of a-CNx thin films due to etching effects. Longer exposure to the etching effect resultingin the creation of small graphitic cluster with the formation of spongy-like porous features.

Synthesis of wide bandgap Ga2O3(Eg ∼ 4.6-4.7 eV) thin films on sapphire by low pressure chemical vapor deposition

This paper presents the synthesis of wide bandgap Ga2O3 thin films on differently oriented sapphire substrates by using low pressure chemical vapor deposition (LPCVD) technique. The effects of substrate orientation on the Ga2O3 thin film surface morphology, crystal orientation, growth rate, and optical properties were studied. The Ga2O3 thin films were synthesized on the c-plane (0001), a-plane (11−20), and r-plane (1−102) sapphire substrates using high purity metallic Ga and oxygen (O2) as source materials and argon (Ar) as carrier gas. The Ga2O3 thin films grown on the c-plane and a-plane sapphire substrates are composed of pure β-Ga2O3. A mixture of β-Ga2O3 and α-Ga2O3 phases is observed for the films grown on r-plane sapphire substrate. Well-distinct transmission, absorption, and reflectance edge at Eg ∼ 4.6–4.7 eV are visible for all the films in the optical spectra measured in the spectral range from 200 to 800 nm.

Synthesis of a-SiO x : H thin films by the gas-jet electron beam plasma chemical vapor deposition method

Thin a-SiOx: H films have been synthesized for the first time by the gas-jet electron beam plasma chemical vapor deposition method. As the substrate temperature increased from room temperature to 415°C, the thin film growth rate decreased from 2 to 1.15 nm/s, the hydrogen concentration in the thin films decreased from 12.5 to 4.2%, and the oxygen concentration increased from 14.5 to 20.8%. A decrease in the hydrogen content is related to enhanced effusion and thermal desorption. The Raman spectra of Si–Si bonds in the films are typical of materials with amorphous structure.

Effect of RF power and gas flow ratio on the growth and morphology of the PECVD SiC thin film s for MEMS applications

Low temperature PECVD (Plasma Enhanced Chemical Vapour Deposition) deposited SiC thin films are promising materials for development of high temperature working MEMS (Microelectromechanical System) due to their excellent mechanical properties, non-corrosive nature and ability to withstand high temperature. However, the surface roughness of such thin films is the main obstacle to achieve thicker thin films for MEMS applications as the surface more rougher by increasing the thickness of PECVD SiC thin films. Therefore, in this present study, thicker SiC thin films were deposited by PECVD process by using the CH4 and SiH4 as the precursor gases in presence of Ar as the carrier gas and two process parameters i.e. RF (Radio Frequency) power with mixed frequency condition and flow ratio of silane to methane were varied by keeping the temperature and pressure constant to investigate the influence of these parameters on the growth rate, surface roughness and morphology of SiC thin films. It was observed that both the RF power (with the mixed frequency condition) and flow ratio of SiH4/CH4 can control the growth rate, surface roughness and morphology of the PECVD SiC thin films. Higher the carbon content in the thin films the surface became more smoother whereas the surface became for rougher by increasing the RF power.