Effect Of Substrate Rotation Research Articles

Effect of substrate rotation on the growth behavior and topography of the [formula omitted] film deposited over a large area using DC magnetron sputtering with a rectangular target: Simulation approach and experiment

It is often challenging to achieve a uniform film with the necessary surface properties when using deposition techniques. If the film is not uniformly deposited or lacks suitable surface roughness, it may not meet performance standards. To understand and control the factors controlling the deposition process, this paper presents a simulation approach to predict the growth behavior of a Ti-film deposited on substrates during the bombardment of the target with argon ions at low pressure. The simulation of the deposition process consists of several Monte Carlo simulations, which include predicting the source of the atoms flow from the target surface and tracing its trajectories through the vacuum chamber until it falls or reaches the surface of the substrates, then predicting the thickness distribution and topography of film. After conducting a comparison between simulation predictions and experimental data, it was found that the measurements obtained using the Profilometer, Scanning Electron Microscope, and Atomic Force Microscopy were relatively close. The results indicate that substrate rotation during deposition leads to a thinner film that is more uniform and less rough, it was also found that the coefficient of variation in the film thickness distribution was improved from 3.96% in the case of a non-rotating substrate to 0.33% in the case of a rotating substrate. The proposed approach can be used to improve the design of magnetron sputtering systems and to provide theoretical guidance for optimizing the thickness distribution and topographical characteristics of the performance specifications of high-quality film without economic constraints.

Effect of substrate rotation and rapid thermal annealing on thermoelectric properties of Ag-doped Sb2Te3 thin films

In this work, homogeneous Ag-doped Sb2Te3 (AST) thin films were prepared using the rf magnetron sputtering technique. Thermoelectric properties of AST films have been investigated in terms of various substrate rotation speeds (20, 40, 60, and 80 rpm) and rapid post-thermal treatments at 250 oCin a vacuum. It was found that the thickness of AST films decreases with the increase in substrate rotation speeds. An Ag atomic composition slightly increases and the other Sb and Te atomic compositions slightly decrease with the increase of substrate speed rotations. The post-thermal treatment improved film crystallinity. Carrier scatterings at the grain boundaries tend to increase the resistivity and the Seebeck coefficient. The maximum power factor of 4.60 mW m−1K−2 (ρ = 19 μΩm, S = 298 μVK−1) is obtained in the AST thin films prepared with the substrate rotation speed of 60 rpm. The practical application of AST films was also reported via a thermoelectric module of five p-AST/n-Bi2Te3thin-film pairs with its achieved output power of 1.6 nW at ΔT = 20 K.

Effects of substrate rotation during AlSi-HiPIMS/Ti-DCMS co-sputtering growth of TiAlSiN coatings on phase content, microstructure, and mechanical properties

A combined high-power impulse and dc magnetron co-sputtering (HiPIMS/DCMS) technique is used to deposit Ti0.6Al0.32Si0.08N films with 1-fold substrate table rotation. Layers are grown at two different substrate-target separations, two different rotational speeds, and with different values of substrate bias. The aim is to study the role of (1) overlap between ion and neutral fluxes generated from HiPIMS and DCMS sources, respectively, and (2) the subplantation range of low-mass ions. Results from X-ray diffractometry highlight the necessity of flux intermixing in the formation of the metastable B1-structured TiAlSiN solid solutions. All films grown at short target-to-substrate distance contain the hexagonal AlN phase, as there is essentially no overlap between HiPIMS and DCMS fluxes, thus the Al+ and Si+ subplantation is very limited. Under conditions of high flux intermixing corresponding to larger target-to-substrate distance, no w-AlN forms irrespective of rotational speed (1 or 3 rpm) and bias amplitude (120 or 480 V), indicating that the role of Al+/Si+ and Ti flux overlap is crucial for the phase formation during film growth by HiPIMS/DCMS with substrate rotation. This conclusion is further supported by the fact that the reduction of the bilayer thickness with increasing the target-to-substrate distance (hence increasing flux overlap) is larger for films grown with higher amplitude of the substrate bias, indicative of more efficient Al+/Si+ subplantation into the c-TiN phase. Single-phase films with the hardness close to that of layers grown with stationary substrate table can be achieved, however, at the expense of higher compressive stress.

Effect of substrate rotation on the microstructure of 8YSZ thermal barrier coatings by EB-PVD

Thermal Barrier Coatings (TBCs) is an essential requirement to protect aero engines and gas turbines against high inlet gas temperatures. The microstructure plays an important role in governing the performance and thermal life cycle of the TBC structure. The TBC deposition process is carried using a combination of the Electron Beam Physical Vapor Deposition (EB-PVD) and Atmospheric Plasma Spray (APS) process. The microstructure obtained by EB-PVD represents columnar structure whereas APS represents splat layer structure. The combined deposition process is used to study the grain growth behavior which can affect the performance of the TBCs. The 8YSZ TBC was deposited by the in-house EB-PVD system onto the Ti-6Al-4V substrate with the NiCrAlY bond coat by the APS process. In this paper, the effect of substrate rotation on the microstructure of 8YSZ TBCs has been investigated and discussed in detail. The dissimilar grain growth behavior of the TBC was observed with the stationary and rotating substrate at 20 rpm for microstructural analysis. It was found that the stationary substrate with 8YSZ TBC has dense and fine grain growth behavior compared to a rotating substrate. In stationary condition, the substrate is always exposed to uniform deposition, therefore the grains with less shadow region is present which results in low porosity. Whereas, a substrate with rotation consists of distributed grains resulting in more shadow region contributing towards high porosity. Therefore, the substrate rotation affects the grain distribution resulting in the shadow region which leads to the formation of pores affecting the performance of TBCs.

Tunable magnetic anisotropy in obliquely sputtered Co60Fe40 thin films on Si(100)

Effect of substrate rotation on the structural, magneto-optic and magneto-transport properties of DC magnetron sputtered Co60Fe40 thin films is investigated. Two thin film samples (each of 20 nm thickness) were prepared by rotating (S-WR) and without rotating (S-WOR) the substrate during deposition. X-ray diffraction (XRD) patterns reveal that the films exhibit textured crystallographic orientation. Surface morphological analysis of these films indicate that the surface of S-WR is smooth in comparison to the sample S-WOR. The magneto-optic Kerr effect analysis reveals that the sample S-WR is isotropic in nature whereas a large uniaxial anisotropy is present in the sample S-WOR due to textured orientation as supported by XRD study. The effect of rotation on the anisotropy is further demonstrated by measuring magneto-resistance (MR) in two configurations, i.e., longitudinal (LMR) and transverse magnetoresistance (TMR) configurations. In the sample S-WOR, the values of MR are quite different, i.e., 0.29% (TMR) and −0.10% (LMR) whereas identical MR values, i.e., 0.19% (for both LMR and TMR), were observed in the sample S-WR. This indicates that the anisotropy in CoFe can be suppressed by rotating the substrates during growth. Thus the tunability of anisotropy is possible by rotating the substrate which is potentially useful for manipulating the properties of ferromagnetic materials for spintronic applications.

Effect of substrate rotation on domain structure and magnetic relaxation in magnetic antidot lattice arrays

Microdimensional triangular magnetic antidot lattice arrays were prepared by varying the speed of substrate rotation. The pre-deposition patterning has been performed using photolithography technique followed by a post-deposition lift-off. Surface morphology taken by atomic force microscopy depicted that the growth mechanism of the grains changes from chain like formation to island structures due to the substrate rotation. Study of magnetization reversal via magneto optic Kerr effect based microscopy revealed reduction of uniaxial anisotropy and increase in domain size with substrate rotation. The relaxation measured under constant magnetic field becomes faster with rotation of the substrate during deposition. The nature of relaxation for the non-rotating sample can be described by a double exponential decay. However, the relaxation for the sample with substrate rotation is well described either by a double exponential or a Fatuzzo-Labrune like single exponential decay, which increases in applied field.

Controlling the anisotropy and domain structure with oblique deposition and substrate rotation

Effect of substrate rotation on anisotropy and domain structure for a thin ferromagnetic film has been investigated in this work. For this purpose Co films with 10 nm thickness have been prepared by sputtering with oblique angle of incidence for various substrate rotations. This method of preparation induces a uniaxial anisotropy due to shadow deposition effect. The magnetization reversal is studied by magneto-optic Kerr effect (MOKE) based microscope in the longitudinal geometry. The Co films prepared by rotating the substrate with 10 and 20 rpm weakens the anisotropy but does not completely give isotropic films. But this leads to high dispersion in local grain anisotropy resulting in ripple and labyrinth domains. It is observed that the substrate rotation has moderate effect on uniaxial anisotropy but has significant effect on the magnetization reversal process and the domain structure.

Microstructure and property changes induced by substrate rotation in titanium/silicon dual-doped a-C:H films deposited by mid-frequency magnetron sputtering

Ti and Si dual-doped hydrogenated amorphous carbon (a-C:H) films were synthesized by mid-frequency (MF) magnetron sputtering with stationary and rotary substrates. The effects of substrate rotation on the microstructure, surface morphology, internal stress and mechanical properties were investigated. The results show that substrate rotation plays an important role in the growth of the a-C:H films. The film deposited on rotary substrate has a higher sp2 content with high degree of bond disorder and relatively low H content, thus resulting in much lower compressive stress and high hardness. The structural changes induced by the substrate rotation are discussed in terms of subplantation and migration roles of incident species in growth of the films. Moreover, the film deposited on rotary substrate shows smoother surface with small and dense particles, which is attributed to suppressing the shadowing effect by rotating substrate.

Effects of substrate rotation in oblique-incidence metal(100) epitaxial growth

The effects of substrate rotation on the surface morphology in oblique-incidence metal(100) epitaxial growth are studied via kinetic Monte Carlo simulations of a simplified model, and compared with previous results obtained without rotation. In general, we find that substrate rotation leads to two main effects. At high deposition angles with respect to the substrate normal, rotation leads to a significant change in the surface morphology. In particular, it leads to isotropic mounds and pyramids with (111) facets rather than the anisotropic ripples and rods observed in the absence of rotation. Due to the existence of rapid transport on these facets, the lateral feature size increases approximately linearly with film thickness. Due to the fact that substrate rotation tends to reduce the effects of shadowing, the surface roughness is also decreased compared to the roughness in the absence of rotation. While this leads to a moderate reduction in the roughness for the case of ballistic deposition, the effect is significantly larger in the case of deposition with attraction. In the case of ballistic deposition, we also find that the surface roughness increases with rotation rate Omega for Omega<1 rev/monolayer (ML) before saturating at larger rotation rates ( Omega>1 rev/ML). In contrast, for the case of attraction the surface roughness exhibits a negligible dependence on rotation rate for finite rotation rate.

Effects of substrate rotation on the microstructure of metal sheet fabricated by electron beam physical vapor deposition

The effects of substrate rotation speed and rotation mode on the microstructure of large-sized metal sheet fabricated by electron beam physical vapor deposition technique were investigated. Helical and columnar microstructures were found in the deposited sheet. Both types of microstructures exhibit no preferential crystallographic orientation. The column inclination under asymmetric vapor incidence pattern was discussed. Integrated vapor incidence angle was found to be effective in evaluating the column inclination.

Compact and Efficient HFCVD for Electronic Grade Diamond and Related Materials

AbstractA compact and efficient hot filament chemical vapor deposition system has been designed for growing electronic-grade diamond and related materials. We report here the effect of substrate rotation on quality and uniformity of HFCVD diamond films on 2” wafers, using two to three filaments with power ranging from 500 to 600 Watt. Diamond films have been characterized using x-ray diffraction, Raman Spectroscopy, scanning electron microscopy and atomic force microscopy. Our results indicate that substrate rotation not only yields uniform films across the wafer, but crystallites grow larger than without sample rotation. Well-faceted microcrystals are observed for wafers rotated at 10 rpm. We also find that the Raman spectrum taken from various locations indicate no compositional variation in the diamond film and no significant Raman shift associated with intrinsic stresses. Results are discussed in the context of growth uniformity of diamond film to improve deposition efficiency for wafer-based electronic applications.

Surface-Enhanced Raman Scattering Immunoassays Using a Rotated Capture Substrate

A rapid, sensitive format for immunosorbent assays has been developed to meet the increasing levels of performance (i.e., reduction of incubation times and detection limits) demanded in the medical, veterinary, and bioterrorism prevention arenas. This paper introduces the concept of a rotating capture substrate as a facile means to increase the flux of antigen and label to the solid-phase surface and thereby reduce assay time. To this end, a sandwich-type assay is carried out that couples the specificity of antibody-antigen interactions with the high sensitivity of surface-enhanced Raman scattering detection. To investigate this strategy, polyclonal anti-rabbit IgG was immobilized on a gold capture substrate via a thiolate coupling agent. The capture substrate, capable of controlled rotation, was then immersed in a sample solution containing rabbit IgG, which served as a model analyte. After binding the target IgG, the substrates were immersed and rotated in an extrinsic Raman label (ERL) labeling solution, which is composed of gold nanoparticles (60 nm) coated with an aromatic moiety as the Raman scatterer and an antibody as the biospecific recognition element. The effect of substrate rotation on both the antigen binding and ERL labeling steps was investigated. Implementation of optimized rotation conditions resulted in the reduction of assay times from 24 h to 25 min and a 10-fold improvement in the limit of detection. Finally, the developed protocol was applied to the detection of rabbit IgG suspended in goat serum, which served to assess performance in a biological matrix.

Morphology and thermal conductivity of yttria-stabilized zirconia coatings

An electron beam directed vapor deposition method was used to grow 7 wt.% Y 2O 3–ZrO 2 (7YSZ) coatings and the effects of substrate rotation upon the coating porosity, morphology, texture, and thermal conductivity were explored. As the rotation rate was increased, the texture changed from 〈1 1 1〉 to 〈1 0 0〉. Under stationary deposition, the coatings were composed of straight columns, while low-frequency rotation resulted in wavy columns. Increases in rotation rate resulted in a gradual straightening and narrowing of the growth columns. The pore fraction slowly decreased as the rotation rate increased. The thermal conductivity was found to be inversely related to the pore fraction. The structural and thermal conductivity alterations are a result of changes to flux shadowing associated with specimen rotation in a gas jet-entrained vapor plume. The minimum thermal conductivity at a low rotation rate is 0.8 W/(m K), well below that of conventionally deposited coatings.

Effect of substrate rotation on structure, hardness and adhesion of magnetron sputtered TiB 2 coating on high speed steel

Titanium diboride (TiB 2) coatings have been deposited on stationary and rotating high speed steel substrates by magnetron sputtering of a TiB 2 target. The structure and hardness of the coatings and the coating–substrate adhesion have been investigated by X-ray diffraction, field emission scanning electron microscopy, nanoindentation and microscratch tests. The results show that substrate rotation has a significant effect on these structural and properties features. It was found that, with substrate rotation, the TiB 2 coating exhibits a columnar structure with random orientation and relatively low hardness and coating–substrate adhesion. On the other hand, without substrate rotation, the TiB 2 coating shows a strong (001) texture with dense, equiaxed grain structure. The hardness and coating–substrate adhesion of the coatings deposited on stationary substrates are much higher than those deposited on rotating substrates. The observed phenomena are discussed in terms of the energy of the sputtered flux, which varies with the substrate–target distance during deposition.

Effect of substrate rotation on texture evolution in ZrO 2-4 mol.% Y 2O 3 layers fabricated by EB-PVD

Changes in the crystallographic texture of thermal barrier coatings (TBCs) produced by electron beam physical vapor deposition (EB-PVD) as a function of substrate-rotation speed have been investigated using SEM, X-ray diffraction and pole figure analysis. It is demonstrated that the substrate rotation strongly influences the morphologies and orientations of the EB-PVD TBC layers. During stationary deposition, (111) planes become oriented parallel to the substrate surface and the deposited layer forms a dense structure instead of the conventional columnar texture. Moreover, the surfaces of stationary samples consist of piles of triangular facets with no particular in-plane orientation. In contrast, when the substrate is rotated, (100) planes form parallel to the surface and many pyramidal facets are observed on the surface by SEM. Columnar grains grew in layers deposited on substrates rotated at speeds from 1 to 10 rev./min. As the rotation speed increased, the width of the columns became thinner and the in-plane orientation became more pronounced. At slow rotation speeds, such as 1 rev./min, the columns developed a wavy structure. In this article, the curvature of the columns is estimated from theory. The difference in the theoretical curvature and that measured experimentally suggests that the shadowing effect has a strong influence on texture growth in EB-PVD TBCs.

The effects of substrate rotation on thermal plasma chemical vapor deposition of diamond

The effects of substrate rotation on the chemical vapor deposition (CVD) of diamond is investigated utilizing a Triple Torch Plasma Reactor (TTPR) activation source. Diamond deposition experiments are conducted with an Ar–H 2–CH 4 plasma gas mixture at reduced pressures. Substrate rotation is achieved by means of a variable speed DC gear motor used to rotate the substrate shaft. Rotation of the substrate during deposition, as well as rotation and offsetting the substrate axis from the converging plasmajet axis, is found to increase the average mass deposition rate as well as the average area of deposit when compared to a stationary substrate. Film and crystal size uniformity of the deposit are found to be enhanced, and deposit roughness decreased by rotating, and rotating plus offsetting the substrate when compared to a stationary substrate. Rotational speed and offsetting the substrate results in negligible differences compared to pure axial rotation. The effect of rotation on substrate temperature is believed to be more significant than the effect of substrate rotation on plasma fluid dynamics.

燃焼炎法による炭素膜合成における基板回転とガス組成の影響

The synthesis of diamond or DLC film in the atmosphere was investigated using an improved combustion flame apparatus equipped with a substrate revolution system. The films have been synthesized at conditions involving of substrate revolution at 0 to 900rpm, a gas composition of C2H2 fixed at 3.0SLM, O2 was 2.4 at 2.7SLM, and deposition time of 90 minutes at atmospheric pressure. The substrates used were cemented carbide (WC-6%Co).Using SEM observation of the surface morphology, deposits were covered with Diamond (111) surfaces with a grain size of 10μm in diameter at C2H2:O2=3.0:2.7gas composition without revolution. The deposits at C2H2:O2=3.0:2.4 consisted of fine grains and the surface appeared glass like. The qualities of the deposits have been estimated using Raman spectroscopy. The deposited film was found to be a diamond, because a Raman band was observed at 1333cm-1 at C2H2:O2=3.0:2.7 gas composition. On the other hand, the deposit at C2H2:O2=3.0:2.4 gas composition have bands at 1350cm-1 and 1600cm-1, and were identified as a mixture of amorphous carbon and graphite. The deposits changed from DLC to diamond with an increase in the oxygen content, and the deposit at C2H2:O2=3.0:2.7 was identified as high quality diamond in particular.The effects of substrate rotation were such that diamond was deposited without revolution, and that deposits changed to DLC consisting of small grains at higher revolutions. The deposit at C2H2:O2=3.0:2.5 gas composition and 600rpm substrate revolution were identified as DLC because Raman bands were displayed at a center band of 1550 cm-1 and at a 1400cm-1 shoulder band. Regarding the effects of revolution, diamond was formed at C2H2:O2=3.0:2.7 without revolution, but the deposited surface because finer with an increase in revolutions. Results of Raman spectra confirmed that the deposits changed from diamond to DLC with revolutions. Control of deposits of either diamond or DLC will be possible via selection of conditions such as gas component or substrate revolution.

Effect of substrate rotation on inter-surface diffusion in MBE for mesa-structure fabrication

Effect of substrate rotation on inter-surface diffusion between (0 0 1) and (1 1 1)B of GaAs(0 0 1) patterned substrates in MBE was studied. Growth on the (1 1 1)B facet was eliminated when rotation speed was high, while the growth occurred at lower rotation speed. These phenomena indicate that, the onset of the growth on (1 1 1)B is determined by whether the amount of Ga adatoms on the surface is sufficient to start 2D-nucleation. We show that 2D-nucleation can be suppressed by rotating the substrate since the adatom concentration on (1 1 1)B is decreased to below the critical value for the nucleation.

Modeling of Epitaxial Silicon Thin‐Film Growth on a Rotating Substrate in a Horizontal Single‐Wafer Reactor

The effect of substrate rotation on transport of reactive gases and epitaxial growth rate is investigated for a horizontal single‐wafer reactor using a model and experiments. The governing equations for gas velocity, temperature, and chemical species transport are solved for the system for Si thin‐film preparation. The rotating substrate causes a circulating gas flow region above itself in which an asymmetric and nonuniform distribution is formed by thermal diffusion and species consumption due to the surface chemical reaction, even when the growth rate profile on the substrate surface is nearly uniform. The thickness of a thin‐film grown at any position is obtained by an integral of the local growth rate along a concentric circle on the substrate surface. The good uniformity in the film thickness observed in calculation and measurement is mainly attributed to the averaging effect by integrating the local growth rate, and partially by the species concentration distribution change, both of which are caused by the rotating motion of the substrate.

Determination of molecular beam epitaxial growth parameters by ellipsometry

The use of ellipsometry as an alternative technique for in situ determination of molecular beam epitaxial growth parameters has been demonstrated. Epitaxial growth has been monitored in real time using three discrete wavelengths to extract growth rates and alloy composition. The effect of substrate rotation on the measured growth rates has also been determined by this technique. From measurements of the GaAs growth rates versus substrate temperature, a value of 4.68±0.12 eV for the activation energy for Ga desorption during GaAs growth was obtained. This agrees with values obtained by other measurement techniques.