Film Deposition Uniformity Research Articles

Monte Carlo simulation of deposition uniformity in the triple-target magnetron co-sputtering system

Magnetron sputtering is an important technology for the preparation of optical, electronic, and mechanical coatings. In these applications, deposition uniformity has a significant impact on the film properties and performance of the devices fabricated by the film. Due to the ion bombardment, the target atoms, namely, the sputtered particles, are emitted to the background gas and finally deposited on the substrate. The film deposition uniformity, therefore, is significantly influenced by the particle transportation process. In this study, a particle transport model was proposed based on MC simulation in COMSOL to analyze the effects of working conditions and geometry parameters on deposition uniformity. It is concluded that the increase in pressure and the decrease in temperature can improve deposition uniformity. Then, the influence of geometry parameters of the triple-target magnetron co-sputtering system is further investigated on the deposition efficiency and deposition uniformity. It is found that the geometry parameters determine the zone with high particle deposition. The closer the zone is to the substrate center, the higher the deposition efficiency. The greater the particle concentration difference on the substrate, the lower the deposition uniformity. Moreover, the optimized parameters were obtained to maximize both the deposition efficiency and deposition uniformity.

Preparation of High-barrier Polyethylene Terephthalate bottle by Microwave Plasma Enhanced Chemical Vapor Deposition

In this work, we reported the investigation of diamond-like carbon (DLC) coating on the inner surface of polyethylene terephthalate (PET) bottles by Microwave Plasma Enhanced Chemical Vapor Deposition to improve their barrier properties. We used 2.45 GHz microwave to generate plasma, acetylene (C2H2) and argon (Ar) were used as monomer gas and diluted gas. The effects of plasma process parameters on deposition uniformity and barrier properties of thin films were studied in detail. In addition, we designed a new antenna shape to improve the uniformity of film deposition. We analyzed the microstructure and morphology of the DLC coating by atom force microscope (AFM). Fourier transform infrared spectroscope (FTIR) and Raman spectroscope were employed to investigate chemical composition and bonding structure. The deposition rate was obtained by Step Profiler. For the barrier properties, we measured the oxygen transmission rate (OTR) of the PET bottle coated with DLC film. It is noted that the uniformity of film deposition is affected by the process parameters and antenna shape, after optimizing the process parameters and antenna shape, the barrier property of PET bottles is improved obviously.

Direct-simulation Monte Carlo modeling of reactor-scale gas-dynamic phenomena in a multiwafer atomic-layer deposition batch reactor

Atomic layer deposition (ALD) using multiwafer batch reactors has now emerged as the manufacturing process of choice for modern microelectronics at a massive scale. Stringent process requirements of thin film deposition uniformity within wafer (WiW) and wafer–wafer (WTW) in the batch, film conformity along submicrometer wafer features, thin film quality, and the utilization of expensive precursors in the reactor dictate ALD reactor design and process parameter optimization. This paper discusses a particle-based direct-simulation Monte Carlo (DSMC) of the full reactor scale simulation that overcomes the low Knudsen number limitation of typical continuum computational fluid dynamics approaches used for modeling low-pressure ALD reactors. A representative industrial multiwafer batch reactor used for the deposition of Si-based thin films with N2 and Si2Cl6 (hexachlorodisilane) as process feed gases with pressures in the range 43–130 Pa and a uniform reactor temperature of 600 °C is simulated. The model provides detailed insights into the flow physics associated with the transport of the precursor species from the inlets, through wafer feed nozzles, into the interwafer regions, and finally through the outlet. The reactor operating conditions are shown to be in the slip/transitional flow regime for much of the reactor volume and especially the feed gas nozzle and interwafer regions (where the Knudsen number approaches ∼0.2), justifying the need for a high-Knudsen number DSMC approach as in this work. For the simulated conditions, the nonuniformity of precursor species immediately above the wafer surface is predicted to be within <1% for a given wafer and <2% across the entire multiwafer stack. Results indicate that higher pressure degrades WiW and WTW uniformity. A reactor flow efficiency is defined and found to be ∼99%, irrespective of the chamber pressure.

Structure and Morphology of Anthraquinone Triazene Films on Silicon Substrate

An optimal imposition method of anthraquinone triazenes on silicon lining was selected. This allowed to create a nanometer film that can be used as dielectric aromatic buffer layers. A morphological research of triazene films shows the existence of delocalized globular anthraquinone macromolecular microformation on the background of triazene uneven layers. The oxidized surface of the triazene substrate is applied better than those without the oxide. This is caused by distribution of electron density in triazene which creates an additional Si/SiO2 coupling system and by presence of voluminous aromatic substituents which impairs the uniformity of film deposition and reduces its thickness.

Stable super-hydrophobic lauryl methacrylate film fabrication on the surface of cotton fabrics in plasma-enhanced chemical vapor deposition with different duty cycles

In this paper, stable super-hydrophobic lauryl methacrylate (LMA) film on the surface of cotton fabrics was fabricated by a simple process of pulsed plasma-enhanced chemical vapor deposition (PECVD) with different duty cycles. The influence of duty cycles on the surface structure and properties of cotton fabrics was analyzed after a series of measurements. The results showed that water contact angles (WCAs) of samples were inversely proportional to the duty cycle values and exhibited the highest WCA (162°) at a duty cycle of 2%. The optimized washing durability of samples was obtained under the treatment of duty cycle of 25% and the WCA could still reach 127° after 15 laundering cycles. The formation of a micro-nano-composite structure and evenness of film could be observed by atomic force microscopy and scanning electron microscopy. Nevertheless, the sample, which was treated by plasma with a 25% duty cycle, had the best uniformity of film deposition. The results of attenuated total reflection Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy illustrated that the LMA monomer was grafted and deposited on the surface of cotton fabrics successfully in covalent binding after PECVD treatment, and this was supposed to be the cause of the washing stability of the films. The results indicated that cotton fabrics modified with the proposed method can exhibit excellent super-hydrophobicity and washing durability, while the duty cycle was an appreciable effect factor in the modification.

Numerical investigation of the film uniformity during the surface coating of charged nanoparticles in a low pressure plasma reactor

The uniformity of film deposition on charged nanoparticles, trapped near the sheath of a capacitively coupled plasma reactor, is studied by numerical simulation of the multi-fluid plasma equations, surface deposition processes, and nanoparticle heating effects. It is found that the anisotropy in the ion flux onto the powered electrode may be hold responsible for the film nonuniformity. The nonuniformity increases with increasing of the particle radius, although small particles lose sphericity faster than the large particles. Because of the electron temperature dependence of the deposition rate and the incident ion flux, higher electron temperatures lead to more nonuniform film deposition. However, the uniformity is improved and the sphericity is restored by the increase in the background gas pressure and/or temperature.

Study on the Influence of Process Parameters on the Distribution of Macro-Particles on the Surface of Films

This paper systematically studies the distribution of macro-particles on the surface of film influenced by the substrate position under conditions of the same magnetic field, different pulsed bias voltage and reaction gas partial pressure, and analyzes the mechanism of macro-particles influenced by different parameters. This study indicates that the substrate position has a better effect on decreasing macro-particles than that of the pulsed bias voltage and particles in different substrate position are very different in their forms and appearances, which easily leads to uneven deposition; under the same bias, the number of particles firstly increases and then decreases with the increasing the distance from substrate position to the center, and the number of particles with over 2μm diameter largely decreases with the increasing the distance from substrate position to the center, so surface morphologies of films are improving; under the lower intensity of magnetic field, the distribution of macro-particles has a great change with the increasing the distance from substrate position to the center, and under the higher intensity of magnetic field, the substrate position has little influence on the distribution of macro-particles on the surface of film. Under the higher intensity (30G) of magnetic field, the distribution of macro-particles on the surface of film has minor change whatever reaction gas partial pressure and substrate position increase, and most particles are small in sizes and are solid spherical in shape. The higher intensity (30G) of magnetic field enhances the uniformity of film deposition and decreases the dependency of macro-particles distribution on other parameters.

Research on Thin Film Thickness Uniformity for Deposition of Rectangular Planar Sputtering Target

Abstract Magnetron sputtering coating is widely applied in the large area deposition, and thin film thickness uniformity, deposition ratio, utilization ratio of target material and other problems in coating industry are paid great attention. As one of the most important parameters for testing sputtering process, the study on the related issues of thin film uniformity is of great theoretical and practical value. The fundamental theory on deposition of sputtering coating is analyzed based on existing theories, and the modelof deposition flux that is composed of fast- and slow-moving particles is applied to the rectangular planar magnetron sputtering target. Through the application of Matlab software and the numerical calculation of thin film deposition uniformity of a rectangular planar magnetron sputtering target, it is easy to come to the following conclusions: the thickness uniformity will reduce with the increase of target-substrate distance and with the decrease of erosion zone of the target ends. When the erosion zone of the target ends increases to some extend, the thin film thickness uniformity will become higher with the increase of target-substrate distance and then become lower. There are two tendencies for thin film thickness uniformity with the increase of length-width ratio of target erosion zone, that is, it will become a little lower when the length is a constant, or become higher when the width is a constant. And the thin film thickness uniformity will become lower with the decrease of po wer and the increase of gas temperature. The deposition rate will become higher with the decrease of target-substrate distance, or the increase of power and gas temperature.

Investigation of diamond deposition uniformity and quality for freestanding film and substrate applications

In this paper, we report on microwave CVD deposition of high quality polycrystalline diamond and on related post-processing steps to produce smooth, flat and uniformly thick films or diamond substrates. The deposition reactor is a 2.45 GHz microwave cavity applicator with the plasma confined inside a 12 cm diameter fused silica bell jar. The deposition substrates utilized are up to 75 mm diameter silicon wafers. The substrate holder is actively cooled with a water-cooled substrate holder to achieve a substrate surface temperature of 600–1150 C. The pressure utilized is 60–180 Torr and the microwave incident power is 2–4.5 kW. Important parameters for the deposition of thick films with uniform quality and thickness include substrate temperature uniformity as well as plasma discharge size and shape. As deposited thickness uniformities of ± 5% across 75 mm diameters are achieved with simultaneous growth rates of 1.9 μm/h. The addition of argon to the deposition gases improves film deposition uniformity without decreasing growth rate or film quality, over the range of parameters investigated. Post-processing includes laser cutting of the diamond to a desired shape, etching, lapping and polishing steps.

Measurement of angular emission trajectories for magnetron-sputtered tantalum

Sputtering target crystallographic orientation affects film deposition uniformity through the emission trajectories of the sputtered atoms. Understanding the relationship between the crystallographic orientation of the sputtering target and the emission trajectory for the sputtered atoms is important for being able to accurately model film thickness uniformity and step coverage. This paper describes the measurement of atom sputter trajectory from a tantalum single crystal. A quartz crystal monitor is used to detect sputter atom flux as a function of angle. The angular sputter emission measurements are consistent with emission from tantalum single crystals along the 〈111〉 close-packed direction as well as the second close-packed 〈100〉 direction. Best fit of the experimental data occurs when the ratio of the emission probabilities in the 〈111〉 and 〈100〉 directions (P〈111〉/P〈100〉) is 1.4, and the ratio of the major and minor axis for the sputter emission ellipsoid (the b/a ratio) is 1.5.

Control of nonlinear distributed process systems: Recent developments and challenges

hile most deal with vv processes undergraduate process control courses still dynamics and control of lumped chemical using linear transfer function models, key technological needs in growth areas such as semiconductor manufacturing, nanotechnology, biotechnology, and unmanned aerial vehicles have motivated extensive research on analysis and control of complex nonlinear distributed systems across all engineering disciplines. From a control point of view, the distinguishing feature of complex distributed systems is that they give rise to nonlinear control problems that involve the regulation of highly distributed control variables by using spatially-distributed control actuators and measurement sensors. Thus, complex distributed systems cannot be effectively controlled with control methods which assume that the state, manipulated and tobe-controlled variables exhibit lumped behavior or with linear control algorithms derived on the basis of IinearAinearized distributed models. icant nonuniformity of the wafer temperature profile. This, in turn, may lead to film deposition uniformity that does not meet the tight requirements set by the industry (SIA, 1997). This technological need and the complex character (nonlinearities, spatial variations, batch nature) of the RTCVD process motivate the need to control the wafer temperature profile using a nonlinear feedback controller based on a distributed process model. A typical example of this class of problems is the control of titania aerosol reactors to achieve a nearly monodisperse particle-size distribution (Kalani and Christofides, 2000); this is required for titania pigments to obtain the maximum hiding powder per unit mass. Titania aerosol Control of Particle-Size Distributions.

Extensions and performance/robustness tradeoffs of the EWMA run-to-run controller by using the internal model control structure

We consider the run-to-run (RtR) correction of input recipes for semiconductor manufacturing processes using measurement information from previous runs. A RtR control algorithm that has been experimentally tested by industry and academia is the EWMA (exponentially weighted moving average) RtR controller. In this paper we provide extensions to this algorithm to address some of its drawbacks and also provide a rigorous theoretical analysis of its properties based on discrete control theory. By formulating the RtR control problem in the internal model control (IMC) structure used in feedback process control, we are able to extend the algorithm to completely eliminate offsets due to unmodeled process drifts, which is a common problem in semiconductor manufacturing. We also develop conditions for robustness with respect to modeling error and measurement delays. Tradeoffs between robustness guarantees and fast RtR response as well as handling of measurement noise are developed and presented in the form of plots that can be used for tuning the parameters of the RtR-IMC controller to accomplish the objectives set by the process engineer. The results are illustrated through several simulations including control of film deposition uniformity in an epitaxial reactor and tungsten deposition rate in a tungsten CVD reactor.

Effect of Buoyancy, Susceptor Motion, and Conjugate Transport in Chemical Vapor Deposition Systems

The fluid flow and heat transfer in the chemical vapor deposition (CVD) manufacturing process are studied numerically. Several crucial aspects such as thermal buoyancy, continuous processing, and conjugate transport are considered. For each aspect, the predicted heat transfer rate and the susceptor temperature are computed and qualitatively linked with the rate and uniformity of film deposition. It is shown that buoyancy effects in helium carrier gas commonly used in diffusion-limited CVD has a negligible effect on deposition rates. Susceptor motion is shown as a feasible alternative to improving the productivity. Conjugate heat transfer effects that arise demonstrate that reactor wall thickness and material may be judiciously chosen to improve temperature uniformity and enhance heat transfer rates, thereby improving deposition rate, film uniformity, and quality.

PATTERN FORMATION IN SOLID FILM GROWTH DURING CVD

This paper deals with the evolution of a gas-solid interface during growth of amorphous CVD films. The aim of the analysis is to show that a comprehensive gas-solid CVD model may simplify significantly under conditions of two limiting cases: kinetic and diffusion-limited growth. The linear stability behavior of the simplified model was found to be almost identical to that of the original and more comprehensive model. It was found that planar film growth was inherently stable under kinetically controlled deposition conditions, but under diffusion-limited conditions, planar film stability depended on the magnitude of the dimensionless group 9Pe, which represents a Damkdhler number of deposition. Numerical solution of the simplified model showed that an increase in 9pe adversely affected the uniformity of film deposition. Predicted morphological phenomena were found to be very similar to experimental observations (Viljoen, et al,1994).

Oxide film deposition by radio frequency sputtering with electron cyclotron resonance plasma stimulation

Various oxide films, including SiO2, ZnO, BaTiO3, SrTiO3, and BaFe12O19, are deposited by 13.56 MHz radio frequency mode (rf-mode) sputtering with 2.45 GHz electron cyclotron resonance (ECR) plasma stimulation. The rf plasma is effectively cooled by the ECR plasma as a result of the shielding effect on the rf electric field on the target surface. This causes the self-bias voltage of the target to decrease and the rf-mode sputtering is effectively performed as in a direct current mode (dc-mode) system. There are two stages in the deposition of the oxide films: an oxygen supply-determining stage controlled by the ECR plasma density, and a sputtered-particle supply-determining stage controlled by the rf sputtering power. In the former stage, the film deposition rate is dramatically enhanced by the ECR plasma irradiation onto the substrate surface (ten times higher than without ECR plasma). In the latter stage, the film deposition rate does not change with oxygen plasma density but with the sputtering power. In this stage, the film deposition uniformity depends only on the uniformity of the sputtered particles. Fully oxidized films can be easily deposited by this technique. Changes of film composition are mainly due to anisotropy of the angle at which sputtered atoms of each component are ejected from the target surface, and also to the sticking efficiency of each component on the film surface with ECR plasma irradiation.

Design and fabrication of a silicon-P(VDF-TrFE) piezoelectric sensor

Using a 70/30 molar ratio vinylidene fluoride/trifluoreethylene copolymer, N-channel enhancement type MOS transistors with extended metal gates were batch fabricated with standard IC technology. Thin (2.5 microm) copolymer film was spin coated on the wafers, electroded, poled, and selectively etched. The small area, thin polymer film on silicon provides good acoustic match to soft tissue, high-frequency response and minimization of losses and noise. Advances in poling procedures and thin polymer film deposition uniformity allowed improvements in the resulting transducers. Fabrication and material property details and measurements of transducer I–V characteristics and low-frequency pyroelectric activities of the processed polymer film on wafer transducers are described. The pyroelectric activity at 25°C of our copolymer film on silicon is 50% higher than that of homopolymer PVDF films.